| 1. |
- ÖZEN, MUSTAFA, 1984, et al.
(författare)
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Continuous Class-E Power Amplifier Modes
- 2012
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Ingår i: IEEE Transactions on Circuits and Systems II: Express Briefs. - 1549-7747 .- 1558-3791. ; 59:11, s. 731-735
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Tidskriftsartikel (refereegranskat)abstract
- In this brief, a continuum of novel closed-form solutions is derived for class-E power amplifiers (PAs). It is analytically proven that the class-E zero voltage/zero voltage derivative switching conditions can be satisfied for an arbitrarily selected reactive second harmonic switch impedance (Z 2 S ). The higher order harmonic currents are terminated capacitively. The conventional class-E, class- E/F 2 , and class-EF 2 modes are thus subsets of the continuum. The arbitrary selection of Z 2 S enables robust waveform engineering for performance optimization in specific applications. Furthermore, the theoretical derivation provides important possibilities for wideband class-E PA synthesis. © 2004-2012 IEEE.
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| 2. |
- Bhandari, Rajendra, et al.
(författare)
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Contrasting lipid biomarkers in mountain rivers in the Nepal Himalayas : Organic matter characteristics and contribution to the fluvial carbon pool
- 2021
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Ingår i: Geoscience Frontiers. - Beijing : China University of Geosciences. - 1674-9871. ; 12:6
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Tidskriftsartikel (refereegranskat)abstract
- The Nepal Himalayas is the source of many glacial and spring-fed river systems crisscrossing the mountainous terrain. There is an increasing recognition of small mountain rivers (SMRs) to have a significant combined export of dissolved and particulate organic carbon to the global carbon flux. We analyzed fluvial sediments from two SMRs and compared the results with two large mountain rivers (LMRs) in Nepal. We investigated the organic matter (OM), its compositional variability, and seasonal export using a suite of lipid biomarkers, namely n-alkanes, n-alkanoic acids, n-alkanols, and sterols. The SMRs indicated a similarity in lipid distribution and were affected by a strong seasonal variability. The LMRs showed a distinct contrast in the distribution of lipids in suspended sediments. Bedload sediments in SMRs were derived from diverse sources with weak terrigenous dominance all-year-round compared to the suspended load. Functional lipids (n-alkanoic acids and n-alkanols) were the major constituents in SMR sediments, indicating better preservation. In contrast, n-alkane concentration dominated over other fractions in suspended sediments retrieved from LMRs. The biomarker trends differentiate SMRs from LMRs with lower transformed/degraded OM in SMRs. A common observation was the strong presence of even carbon compounds in short-chain n-alkanes in SMR bedload sediments and their predominance in suspended sediments in LMRs. Such an unusual trend is attributed to specific biomarker sources from the catchment and ongoing processes in fluvial systems. Topsoil colonized by fungal species under moist acidic conditions and autochthonous bacteria contributes to the organic matter pool in shallow SMRs. In LMRs, the contribution from thermally mature sedimentary hydrocarbons and the diagenetic reduction of nalkanoic acids to n-alkanes are additional contributors to the allochthonous carbon pool. The differences in lipid concentrations, their distribution, seasonality, and the size of rivers suggest differential preservation/degradation of the organic matter pool and their importance in contributing to the carbon budget. (c) 2021 China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/
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| 3. |
- Drake, Isabel, et al.
(författare)
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A high eating frequency is associated with an overall healthy lifestyle in middle-aged men and women and reduced likelihood of general and central obesity in men.
- 2010
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Ingår i: British Journal of Nutrition. - 1475-2662. ; 104, s. 1065-1073
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Tidskriftsartikel (refereegranskat)abstract
- The role of eating frequency in obesity development is debated. Therefore, we investigated the association between eating frequency, BMI and waist circumference (WC), as well as how eating frequency is related to diet composition and lifestyle factors. A subsample (aged 47-68 years) of men (n 1355) and women (n 1654) from the Malmö Diet and Cancer cohort was used for the present cross-sectional study. The daily eating frequency was calculated based on the number of self-reported eating occasions during an ordinary day. Regression analysis and ANOVA examined the associations between eating frequency, BMI and WC, while adjusting for potential confounders. The energy percentage (E%) from carbohydrates as well as relative fibre intake (g/MJ) increased with higher eating frequency; while E% from fat, protein and alcohol decreased. A low daily eating frequency was associated with smoking, higher alcohol consumption, and lower leisure-time physical activity. Eating three or fewer meals per d was also associated with increased likelihood of general and central obesity in men when adjusting for total energy intake, lifestyle and dietary factors. However, results did not reach statistical significance among women. The present study suggests that a high daily eating frequency is associated with a healthy lifestyle and dietary pattern in both men and women, and a reduced likelihood of general and central obesity in men. There is a need for prospective studies investigating the association between eating frequency, diet and body composition.
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| 4. |
- Johansson, Magnus, 1972
(författare)
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Synthesis and Applications of P-chirogenic Phosphine Boranes
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- AbstractThis thesis reports the independent synthesis of both enantiomers of P-chirogenic phosphine ligands and the building blocks thereof, which are suitable for parallel synthesis efforts and for the generation of more diverse libraries of P-chirogenic compound. The use of P-chirogenic phosphine boranes in transition metal-catalyzed reactions, such as palladium-catalyzed allylic alkylation and amination, is also described. Papers I and II describe the synthesis and evaluation of different chiral diamines in the enantioselective deprotonation of alkyl- and aryl-substituted prochiral phosphine boranes. Although (-)-sparteine ligated to sec-BuLi is reported to give high enantioselectivity in the deprotonation of prochiral phosphine-borane, this methodology suffers from the lack of availability of (+)-sparteine. We have shown that diamines derived from the quinolizidine alkaloid (-)-cytisine, which is extracted from the Golden Rain Tree (Laburnum anagyroides), are excellent substitutes for (+)-sparteine and thus facilitate the preparation of both enantiomers of a P-chirogenic phosphine via enantioselective deprotonation.The utility of P-chirogenic scaffolds obtained by desymmetrization is presented in Papers III, IV and V. A set of new P-chirogenic building blocks was synthesized via asymmetric deprotonation and utilized in the further syntheses of libraries of different P,N ligands or α-carboxyphosphine boranes. Applications of the phosphine boranes as pro-ligands in palladium-catalyzed reactions are also described.In Paper VI, a novel biocatalytic desymmetrization of prochiral phosphine-boranes mediated by lipase B of Candida antarctica is presented. Both enantiomers can be prepared with good to excellent enantioselectivity either through hydrolysis of a prochiral diacetate or via acylation of a prochiral diol.Finally, Paper VII describes a highly stereoselective and enantioselective Au(I)-catalyzed intermolecular olefin cyclopropanation. This reaction is based on an intermediate gold-carbenoid species, derived via a Rautenstrauch rearrangement of different propargyl esters, which is trapped by olefin to form multi-substituted cyclopropanes with defined regiochemistry and stereochemistry.In summary, this work has extended the area of P-chirogenic phosphine ligands to include both enantiomers at phosphorus, via either enantioselective deprotonation or enzyme catalysis. The importance of P-chirogenic phosphine ligands in asymmetric catalysis is displayed by their frequent as ligands to transition metals in the synthesis of all kinds of chiral compounds, including several different pharmaceuticals. Accordingly, access to both enantiomers of a chiral ligand is of outmost importance. These ligands, as well as and ligands having axial chirality, have then been utilized successfully in palladium catalyzed allylic alkylation and in gold catalyzed olefin cyclopropanation, affording chiral material of high optical purity.
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| 5. |
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| 6. |
- Scaramuzzino, Roberto, et al.
(författare)
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Factors Explaining Swedish Civil Society Organizations’ Europeanization
- 2019
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Ingår i: Europeanization in Sweden : Opportunities and Challenges for Civil Society Organizations - Opportunities and Challenges for Civil Society Organizations. - 9781789200348 - 9781789200355 ; , s. 108-120
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Bokkapitel (refereegranskat)
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| 7. |
- Jackson, N., et al.
(författare)
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LBCS: The LOFAR Long-Baseline Calibrator Survey
- 2016
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 595, s. Art no A86-
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Tidskriftsartikel (refereegranskat)abstract
- We outline the LOFAR Long-Baseline Calibrator Survey (LBCS), whose aim is to identify sources suitable for calibrating the highest-resolution observations made with the International LOFAR Telescope, which include baselines > 1000 km. Suitable sources must contain significant correlated flux density (greater than or similar to 50 - 100 mJy) at frequencies around 110-190 MHz on scales of a few hundred milliarcseconds. At least for the 200-300-km international baselines, we find around 1 suitable calibrator source per square degree over a large part of the northern sky, in agreement with previous work. This should allow a randomly selected target to be successfully phase calibrated on the international baselines in over 50% of cases. Products of the survey include calibrator source lists and fringe-rate and delay maps of wide areas-typically a few degrees-around each source. The density of sources with significant correlated flux declines noticeably with baseline length over the range 200-600 km, with good calibrators on the longest baselines appearing only at the rate of 0.5 per sq. deg. Coherence times decrease from 1-3 min on 200-km baselines to about 1 min on 600-km baselines, suggesting that ionospheric phase variations contain components with scales of a few hundred kilometres. The longest median coherence time, at just over 3 min, is seen on the DE609 baseline, which at 227 km is close to being the shortest. We see median coherence times of between 80 and 110 s on the four longest baselines (580-600 km), and about 2 min for the other baselines. The success of phase transfer from calibrator to target is shown to be influenced by distance, in a manner that suggests a coherence patch at 150-MHz of the order of 1 deg. Although source structures cannot be measured in these observations, we deduce that phase transfer is affected if the calibrator source structure is not known. We give suggestions for calibration strategies and choice of calibrator sources, and describe the access to the online catalogue and data products.
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| 8. |
- Jackson, N Mike, et al.
(författare)
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Thermal fatigue cracking of asphalt concrete pavements an experimental approach
- 1991
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Ingår i: Proceedings of Strategic Highway Research Program and Traffic Safety on Two Continents. Conference in Gothenburg, Sweden, September 18-20, 1991. - Linköping : Statens väg- och transportforskningsinstitut. ; , s. 53-68
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 9. |
- Lasich, Matthew, et al.
(författare)
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Influence of unlike dispersion interactions in modeling methane clathrate hydrate
- 2014
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Ingår i: Fluid Phase Equilibria. - : Elsevier BV. - 0378-3812 .- 1879-0224. ; 381, s. 108-115
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Tidskriftsartikel (refereegranskat)abstract
- Studies of the thermodynamic stability of clathrate hydrates of natural gas (mostly methane) is important in fields such as offshore gas exploitation and energy storage. Two approaches were used to study the effect of unlike dispersion interactions on methane clathrate hydrates: grand canonical Monte Carlo simulations (which yield adsorption data directly and can be used to infer phase equilibria), and estimation of the heat of dissociation coupled with the Clausius–Clapeyron equation (to calculate the phase equilibria, at the expense of providing no information about the adsorption behavior). It was found that the adsorption isotherm parameters change monotonically with respect to unlike dispersion interactions, although a perfect fit to experimentally-derived values may not be possible, at least using the force fields considered in this study. The heat of dissociation changes monotonically due to changes in the unlike dispersion interaction, and a best fit value of the Berthelot correction factor is achieved.
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| 10. |
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