| 1. |
- Anderbrant, Olle, et al.
(författare)
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Release of sex pheromone and its precursors in the pine sawfly Diprion pini (Hym., Diprionidae)
- 2005
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Ingår i: Chemoecology. - : Springer Science and Business Media LLC. - 0937-7409 .- 1423-0445. ; 15:3, s. 147-151
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Tidskriftsartikel (refereegranskat)abstract
- The first identification of a sex pheromone of a pine sawfly (Hymenoptera, Diprionidae) dates back almost thirty years. Since then, female-produced pheromones of over twenty diprionid species have been investigated by solvent extraction followed by separation and identification. However, no study has shown what the females actually release. Collection of airborne compounds using absorbtion on charcoal filter as well as solid phase microextraction (SPME) followed by analysis employing gas chromatography combined with mass spectrometry (GC-MS), revealed an unusual system in Diprion pini, in which the pheromone precursor alcohol, 3,7-dimethyl-2-tridecanol, is released together with acetic, propionic, butyric and isobutyric acids. The corresponding acetate, propionate and butyrate esters of 3,7-dimethyl-2-tridecanol were also found in the samples. All esters were electrophysiologically active, and the propionate and isobutyrate were attractive in trapping experiments. Based on these and earlier reported results, it seems that at least in part of its range, the pheromone response of D. pini is not very specific with regard to the functional group, as long as this is an ester.
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| 2. |
- Lyytikäinen-Saarenmaa, P, et al.
(författare)
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Monitoring the European pine sawfly with pheromone traps in maturing Scots pine stands
- 2006
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Ingår i: Agricultural and Forest Entomology. - : Wiley. - 1461-9555 .- 1461-9563. ; 8:1, s. 7-15
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Tidskriftsartikel (refereegranskat)abstract
- 1. During 1989-93, field studies were conducted in Finland to develop a method based on pheromone traps to monitor and forecast population levels of the European pine sawfly (Neodiprion sertifer Geoffr.) and tree defoliation. 2. Three traps per site were baited with 100 μg of the N. sertifer sex pheromone, the acetate ester of (2S,3S,7S)-3,7-dimethyl-2-pentadecanol (diprionol), in maturing pine stands in southern and central Finland. In addition, three different dosages (1, 10 and 100 μg) of the pheromone were tested in 1991-92. 3. The highest number of males was observed in traps baited with the highest dose. On average, there was a 10-fold increase in trap catch between lure doses. 4. Density of overwintering eggs was used to evaluate the effectiveness of pheromone traps in predicting sawfly populations. The proportion of healthy overwintering eggs was determined each year. A model based on the number of current shoots on sample trees, diameter at breast height and tree height was formulated to estimate eggs per hectare. 5. Linear regression analysis produced high coefficients of determination between number of males in traps and density of total eggs in the subsequent generation, when populations were at peak densities. The relationships were not significant for low population densities. The results indicate a risk of moderate defoliation when the seasonal trap catch is 800-1000 males per trap or higher.
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| 3. |
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| 4. |
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| 5. |
- Blomé, Gunnar
(författare)
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Kundnära organisation och serviceutveckling i bostadsföretag
- 2006
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The purpose of the study is to increase knowledge of how to provide service in municipal housing companies in Sweden, and of various organisational models for the customer-centric organisation. The principal issue of the study is how housing companies can organise their resources in order to create an efficient and customer-centric organisation. The term customer-centric organisation comprises customer service, letting, and local administration. Customer service is often designated as the housing company’s fault reporting service and includes, for instance, the reporting of faults in dwellings, noise problems, complaints etc. Letting incorporates processes connected with estate agency, marketing, taking possession and vacating, internal exchanges, housing strategies, options, and tenant selection. Local administration incorporates processes connected with day-to-day operational administration, i.e. the provision of service with regard to remedying faults and making repairs. The study’s theoretical points of departure have their basis in research into public housing and the field of service management. The empirical supportive data used in the study is a two-year case study of rganisational changes at Malmö municipal housing company, MKB Fastighets AB (MKB), and a supplementary interview study at four other municipal housing companies. The case study was conducted with the help of observations gleaned from MKB’s internal evaluation group, interviews with management and frontline staff, and a questionnaire survey of frontline staff in MKB’s customer-centric organisation. The supplementary study included interviews with both frontline staff and management. MKB’s organisational change can be divided up into two different phases: the test organisation and the team organisation. The departure point of both organisations was area-based customer service, letting, and local administration. The test organisation entailed MKB creating one single function to manage all these activities. Due to higher administration costs, less visible local administration, and recruitment problems, the test organisation was abandoned. In its place, the team organisation was created, which in many respects consisted of the same concept, but differed in that the area-based customer service, letting, and local administration were shared between several people in a joint local work-team. MKB’s new ways of organising its customer-centric organisation are defined in the study as a holistic model, entailing that all contact with customers was self-managed from a local area office. The results show that the team organisation cultivates a proximity to the customers, also improving customer responsibility and collaboration between frontline staff. It can also be pointed out that the customer-centric organisation needs to be developed further. Among other things, the expertise of frontline staff can be further adapted in order to meet customer requirements. At the same time, it is of great importance to the outcome of the organisational change that the organisation’s overarching parts are coordinated in a manner facilitating the work of frontline staff in the provision of service. The same will apply if the housing company uses contractors in, for instance, property maintenance, grounds management, and heating, ventilation and sanitation installations. If the housing company’s aim is to become customer-oriented, then joint resources will have to be concentrated on the customer process and this process will have to take centre stage in the company’s strategic management decisions.
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| 6. |
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| 7. |
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| 8. |
- Fransson, Ann-Britt L., 1973-
(författare)
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Deracemization of Functionalized Alcohols via Combined Ruthenium and Enzyme Catalysis
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The major part of this thesis describes the synthesis of enantiopure alcohols and diols by combining ruthenium-catalyzed racemization or epimerization and lipase-catalyzed asymmetric transformations. A minor part of this thesis is focused on ruthenium-catalyzed redox reactions for transfer hydrogenation of 1,3-cycloalkanediketones. Kinetic resolution of racemic γ-hydroxy acid derivatives was performed via Pseudomonas cepacia lipase (PS-C)-catalyzed transesterification. γ-Hydroxy esters and γ-hydroxy amides were studied showing in higher selec-tivity and yields for the γ-hydroxy amides. The enzyme PS-C tolerates both variation in the chain length and different functionalities giving good to high enantioselectivity. Combining enzymatic kinetic resolution with a ruthenium-catalyzed racemization led to a dynamic kinetic resolution (DKR). The use of 2,4-dimethyl-3-pentanol as a hydrogen source to suppress ketone formation in the dynamic kinetic resolution increased the yields of the acetate product. The synthetic utility of this procedure was illustrated by the practical synthesis of the γ-lactone (R)-5-methyltetrahydrofuran-2-one. A distereoselective transformation of cis/trans-1,3-cyclohexandiol using Candida antarctica lipase B (CALB)-catalyzed transesterification was of interest. Desymmetrization of cis-1,3-cyclohexanediol to the (R-monoacetate was successfully accomplished. Enantiopure (R,R)-diacetate was obtained from the (R)-monoacetate in a DYKAT process at room tem-perature. Metal- and enzyme-catalyzed transformation of cis/trans-1,3-cyclohexanediol using PS-C, gives a high diastereoselectivity for cis-diacetate. The (S)-mono-acetate was obtained from cis-diacetate by CALB-catalyzed hydrolysis. In addition, it was shown, by the use of deuterium-labeling that intramolecular acyl migration does not occur in the transformation of cis-monoacetate to the cis-diacetate. Ruthenium-catalyzed transfer hydrogenation of 1,3-cyclohexanedione under microwave heating was developed as an efficient and fast method for the preparation of 1,3-cycloalkandiols.
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| 9. |
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| 11. |
- Högberg, Hans-Erik
(författare)
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Exploiting enantioselectivity of hydrolases in organic solvents
- 2008
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Ingår i: Organic Synthesis with Enzymes in Non-Aqueous Media. - Weinheim : Wiley-VCH Verlagsgesellschaft. - 9783527318469 - 9783527318469 ; , s. 73-112
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- In modern organic chemistry the synthesis of chiral enantiopure compounds is an extremely important objective. To achieve this, biocatalysts have emerged as key tools. The broad reactivity of hydrolytic enzymes combined with their ability to discriminate between enantiomers make them ideal catalysts for resolving racemic organic compounds to provide enantiomerically enriched products. This chapter gives an overview of how the enantioselectivity of hydrolases can be exploited to furnish virtually enantiopure compounds via kinetic resolution of racemic compounds and desymmetrisation of symmetric compounds. Enantioselectivity and E-values are discussed. Reversibility of hydrolase-catalysed reactions and how it can be avoided by using various irreversible acyl donors as well as the determination and optimization of enantioselectivity are briefly discussed. The bulk of the chapter consists of selected examples of hydrolase catalysed reactions of some important classes of compounds. Thus the usefulness of hydrolase-catalyzed reactions is demonstrated by several examples of reactions in organic solvents of primary, secondary, tertiary alcohols, various amines, and acid derivatives.
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| 12. |
- Isaksson, Dan, et al.
(författare)
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Enantiomerically enriched cryptone by lipase catalysed kinetic resolution
- 2006
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Ingår i: Tetrahedron. - : Elsevier BV. - 0957-4166 .- 1362-511X. ; 17:2, s. 275-280
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Tidskriftsartikel (refereegranskat)abstract
- Thiophenol was added to racemic cryptone (4-isopropyl-2-cyclohexene-1-one) and the resulting 1,4-addition products, cis- and trans-4-isopropyl-3-(phenylsulfanyl)cyclohexanone) were separated and the latter reduced to rac-1,3-cis-1,4-trans-4-isopropyl-3-(phenylsulfanyl)cyclo¬he¬xanol which was subjected to lipase catalysed resolution by acylation catalysed by CAL-B (Candida antarctica lipase B). The remaining alcohol was separated from the produced acetate, which was hydrolysed to the alcohol. The enantiomeric alcohols so obtained were oxidised. The initial products, probably sulfoxidoketones spontaneously decomposed to furnish enantiomerically enriched (R)- and (S)-cryptone with up to 76% and 98% ee, respectively.
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| 13. |
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| 14. |
- Liu, Rong
(författare)
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Enzymes as catalysts in synthesis of enantiomerically pure building blocks : secondary alcohols bearing two vicinal stereocenters
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Enzymes as tools in organic synthesis have provided enormous advantages. This thesis deals with the applications of enzymes in the kinetic resolutions of racemic compounds. The stereochemistry of chiral compounds and the kinetics of α/β hydrolase lipases are presented. From a practical point of view, the handling of a large number of parameters that influences the kinetic resolutions, especially enantioselectivity (E-value) are systematically described. A variety of approaches employed for raising the yields to over 50% are additionally discussed. Methods for the preparation of synthetically useful chiral building blocks were developed in this thesis. Thus, resolution of secondary alcohols bearing two vicinal stereocentres are studied. These building blocks can serve as starting materials for the synthesis of various enantiomerically pure compounds for agrochemistry, pharmaceuticals, chemical industry, and particularly for the total synthesis of pheromones. Racemic 3-substitued 2-hydroxybutane derivatives were produced in fairly high diastereomeric purities by a variety of chemical approaches, such as epimerization, metal-catalysed asymmetric addition etc. Kinetic resolution of these racemates was achieved by enzyme-catalysed reactions. Two lipases, Candida antarctica lipase B and Pseudomonas cepacia lipase were found to be useful in acylations as well as hydrolyses. In the biotransformations studied, the presence and nature of the second vicinal stereocentre in the chiral secondary alcohols investigated seemed to be important, e.g. in terms of the efficiencies of sequential kinetic resolutions, and altering the selectivities as well.
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| 15. |
- Liu, Rong, et al.
(författare)
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Preparation of the four stereoisomers of 3-bromo-2-butanol or their acetates via lipase-catalysed resolutions of the racemates derived from dl- or meso-2,3-butanediol
- 2005
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Ingår i: Tetrahedron. - : Elsevier BV. - 0957-4166 .- 1362-511X. ; 16:15, s. 2607-2611
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Tidskriftsartikel (refereegranskat)abstract
- The four stereoisomeric 3-bromo-2-butanols and/or their acetates were prepared via lipase-catalysed kinetic resolution by hydrolyses of the acetates of the (+/-)-syn- and (+/-)-anti-3-bromo-2-butanols, or via esterifications of the alc hols. The diastereomeric bromoacetates were obtained by syntheses from the dl- and meso-2,3-butanediols, respectively. On a preparative scale, the four stereoisomers, either as the free alcohols or as their acetates, were obtained in > 95% ee, and in 35-40% yield (based on the starting racemates).
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| 16. |
- Verheggen, F, et al.
(författare)
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Electrophysiological and Behavioral Activity of Secondary Metabolites in the Confused Flour Beetle, Tribolium confusum
- 2007
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Ingår i: Journal of Chemical Ecology. - : Springer Science and Business Media LLC. - 0098-0331 .- 1573-1561. ; 33:3, s. 525-539
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Tidskriftsartikel (refereegranskat)abstract
- Several previous studies have addressed pheromone communication in various flour beetles (Coleoptera: Tenebrionidae), including the confused flour beetle, Tribolium confusum (du Val). Different stereoisomers of 4,8-dimethyldecanal (DMD) were reported as the only components of an aggregation pheromone, but the behavioral activity of DMD is low. In the present study, additional previously reported secondary metabolites (benzoquinones and hydrocarbons) were tested for electrophysiological activity (EAG) with both sexes of T. confusum. Two benzoquinones and three monoenic hydrocarbons elicited significant EAG activity from both male and female antennae. There was an elevated male EAG response (vs. the females) to two out of the three hydrocarbons and for both quinones. The EAG-active compounds were subsequently investigated for behavioral activity in a walking bioassay. Benzoquinones are considered toxic and have been assigned a function as alarm substances in flour beetles, but we found that methyl-1, 4-benzoquinone in intermediate concentrations was attractive to both male and female beetles and could therefore act as an aggregation pheromone component. Males were also attracted to ethyl-1,4-benzoquinone. The corresponding hydroquinones, presumed precursors of the benzoquinones, did not elicit any electrophysiological response and were not tested for behavioral activity. The unsaturated hydrocarbons (1-tetradecene, 1-pentadecene, and 1-hexadecene) elicited significant EAG responses from both male and female antennae and were also attractive in the behavioral assay. Our results show that several beetle-produced compounds, in addition to 4,8-dimethyldecanal, may be part of a complex pheromone system in flour beetles and play a role in mediating aggregation in T. confusum.
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| 17. |
- Wilhelmsson, O., et al.
(författare)
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Deposition and characterization of ternary thin films within the Ti-Al-C system by DC magnetron sputtering
- 2006
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Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248 .- 1873-5002. ; 291:1, s. 290-300
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Tidskriftsartikel (refereegranskat)abstract
- The formation of ternary compounds within the Ti-Al-C system was studied by magnetron sputtering for thin-film deposition and first-principles calculations for phase stability. As-deposited films were characterized with X-ray diffraction (XRD) and high-resolution transmission electron microscopy (TEM). The hardness and Young's moduli of the material were studied by nanoindentation. Epitaxial and phase-pure films of Mn+1AXn phases Ti3AlC2 and Ti2AlC as well as the perovskite phase Ti3AlC were deposited on Al2O3(00l) wafers kept at temperatures between 800 and 900 °C. The only ternary phases observed at low temperatures (300 °C) were Ti3AlC and cubic (Ti,Al)C, the latter can be described as a metastable solid solution of Al in TiC similar to the more studied (Ti,Al)N system. The difficulties to form MAX phases at low substrate temperatures were attributed of requirement for a sufficient diffusivity to partition the elements corresponding to the relatively complex crystal structures with long c-axes. While MAX-phase synthesis at 800 °C is significantly lower than contemporary bulk sintering processes, a reduction of the substrate temperature towards 300 °C in the present thin-film deposition experiments resulted in stacking sequence variations and the intergrowth of (Ti,Al)C. © 2006 Elsevier B.V. All rights reserved.
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