| 1. |
- Andersson, Sofia E M, 1979, et al.
(författare)
-
Activation of Fms-like tyrosine kinase 3 signaling enhances survivin expression in a mouse model of rheumatoid arthritis.
- 2012
-
Ingår i: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 7:10
-
Tidskriftsartikel (refereegranskat)abstract
- Survivin is known as an inhibitor of apoptosis and a positive regulator of cell division. We have recently identified survivin as a predictor of joint destruction in patients with rheumatoid arthritis (RA). Flt3 ligand (Flt3L) is expressed in the inflamed joints and has adjuvant properties in arthritis. Studies on 90 RA patients (median age 60.5 years [range, 24-87], disease duration 10.5 years [range, 0-35]) show a strong positive association between the levels of survivin and Flt3L in blood. Here, we present experimental evidence connecting survivin and Flt3L signaling. Treatment of BALB/c mice with Flt3L led to an increase of survivin in the bone marrow and in splenic dendritic cells. Flt3L changed the profile of survivin splice variants, increasing transcription of the short survivin40 in the bone marrow. Treatment with an Flt3 inhibitor reduced total survivin expression in bone marrow and in the dendritic cell population in spleen. Inhibition of survivin transcription in mice, by shRNA lentiviral constructs, reduced the gene expression of Flt3L. We conclude that expression of survivin is a downstream event of Flt3 signaling, which serves as an essential mechanism supporting survival of leukocytes during their differentiation, and maturation of dendritic cells, in RA.
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| 2. |
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| 3. |
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| 4. |
- Bergh, Mats, 1968, et al.
(författare)
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The influence of surface micro-roughness on bondability
- 1995
-
Ingår i: Proceedings of the Third International Symposium on Semiconductor Wafer Bonding: Physics and Applications. ; , s. 126-
-
Konferensbidrag (refereegranskat)abstract
- The requirements on a surface in terms of micro-roughness necessary to achieve spontaneous bonding on wafer contact have been investigated. Wafers from four different manufacturers, all having their special surface characteristics, were evaluated using atomic force microscopy. Their room temperature bondability was investigated using the contact wave velocity and the surface energy of the formed bond as parameters. Different wet cleaning procedures were used to modify the micro-roughness of the silicon surface. It is found that the surface rms roughness value is not a good measure for judging the bondability of a surface. Instead we propose the use of the Fourier spectrum of the surface roughness. The occurrence of low, ~0.001 Å-1, spatial frequency components of large amplitude in the Fourier spectrum of the surface roughness may affect the bondability of the surface negatively while higher frequency components are not as important
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| 5. |
- Björk, Yvonne, et al.
(författare)
-
Androgens in women after allogeneic hematopoietic cell transplantation : Impact of chronic GvHD and glucocorticoid therapy
- 2017
-
Ingår i: Bone Marrow Transplantation. - : Springer Science and Business Media LLC. - 0268-3369 .- 1476-5365. ; 52:3, s. 431-437
-
Tidskriftsartikel (refereegranskat)abstract
- Low androgen levels may contribute to sexual dysfunction in women after allogeneic hematopoietic cell transplantation (alloHCT). However, data on serum androgens in women after alloHCT are limited. The aim of this study was to assess androgen levels and their association with chronic GvHD (cGvHD) and glucocorticoid (GC) therapy. Included were 65 allografted women, 33 with cGvHD, and 23 of these were on GC therapy. Controls were 94 healthy, age-matched women. Supportive study groups were women after autologous HCT (autoHCT; n=20) and non-transplanted women on GC therapy (n=26). Compared with controls, free testosterone (free T) and dehydroepiandrosterone sulfate (DHEAS) levels were lower in both the alloHCT group and GC groups; P<0.0001 and P<0.05, respectively. Androgens in the autoHCT group were similar or higher than controls. In the subgroup of alloHCT patients without cGvHD, free T was similar to controls (7.2 vs 8.6 pmol/L; P=0.42), whereas DHEAS levels was lower than controls (1.7 vs 2.5 μmol/L; P=0.008). Compared with controls, cGvHD without GC (n=10) was associated with lower free T and DHEAS; P=0.004 and P=0.0004, respectively). The lowest androgen levels were seen in women with both cGvHD and GC therapy. In conclusion, low serum androgens were associated with cGvHD and GC therapy, prompting for studies assessing a possible association between low androgens and sexual dysfunction and quality of life in allografted women.
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| 6. |
- Du, Chengjun, 1985, et al.
(författare)
-
An analysis of image evaluation procedures for measurements of diesel spray characteristics
- 2014
-
Ingår i: ILASS – Europe 2014, 26th Annual Conference on Liquid Atomization and Spray Systems, 8-10 Sep. 2014, Bremen, Germany.
-
Konferensbidrag (refereegranskat)abstract
- In order to investigate the influence of the methods applied for measuring spray parameters such as liquid phase spray penetration and dispersion cone angle, Diesel spray experiments in a high pressure / high temperature chamber were performed under non-evaporating (30 ºC, 21.1 bar), evaporating (350 ºC, 43.4 bar) and combusting (600 ºC, 60 bar) conditions with a constant gas density 24.3 kg/m3. A high-speed video camera was used to record shadowgraph images. The images were analyzed both as individual images and as averages of 100 images at each time step. The influence of the threshold level to define the spray boundary on the measured spray penetration and dispersion cone angle was analyzed. Under non-evaporating and evaporating conditions, it was found that a change in threshold level has a larger influence on the values for the liquid spray penetration determined from the averaged images, compared to the values from the instantaneous images. The penetration lengths determined from the instantaneous and averaged images are generally quite similar. Under combusting conditions, during the early phase of the injection there are only small differences in the penetration length between the instantaneous and averaged images or when the threshold level is changed, which is in strong contrast to the later part where there is a high sensitivity to changes in the threshold level and there can be significant differences in lengths determined from instantaneous and averaged images. The spray dispersion angle was calculated along the whole spray based on the width at each distance from the nozzle tip. It was found that there is a region around 12 mm from the nozzle tip where the measured spray cone angle is constant during most of the injections. Further downstream the dispersion angle increases till about 75 % of the penetration length under non-evaporating and evaporating conditions, whereas it decreases under combusting conditions.
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| 7. |
- Du, Chengjun, 1985, et al.
(författare)
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Effect of Nozzle Geometry on Diesel Spray Characteristics under Non-Evaporating and Evaporating Conditions
- 2015
-
Ingår i: ICLASS 2015 - 13th International Conference on Liquid Atomization and Spray Systems.
-
Konferensbidrag (refereegranskat)abstract
- To investigate the effect of nozzle geometry on diesel spray characteristics, spray experiments were car-ried out in a spray chamber. Three different single-hole nozzles were used: (1) nozzle N1 - outlet diameter 140 µm with k-factor 0; (2) nozzle N2 - outlet diameter 140 µm with k-factor 2; (3) nozzle N3 - outlet diame-ter 136 µm with k-factor 2. Two constant gas densities of 15 kg/m3 and 30 kg/m3 were maintained under non-evaporating (ambient temperature 40 ºC) and evaporating (ambient temperature 400 ºC) conditions. The range of injection pressure was from 800 bar to 1600 bar. Liquid phase spray penetration and local spray cone angle along the spray profile were measured based on high speed shadowgraph images. In addition, spray momen-tum flux was measured. It was found that the effect of nozzle geometry on the liquid phase penetration and local spray cone angle were different for different gas density and injection pressure. Under non-evaporating conditions, as injection pressure was increased, nozzle N1 without conicity showed slightly slower liquid penetration and larger local cone angle than nozzles N2 and N3 at the density 15 kg/m3. As the gas density was increased to 30 kg/m3, the difference between the three nozzles was more evident. Under evaporating conditions, nozzle N3 with conicity showed shorter liquid phase penetration than nozzle N1. As the gas densi-ty is increased to 30 kg/m3, comparing the two nozzles (N1 and N2) which have the same outlet diameter but with different conicity, nozzle N2 with conicity showed longer liquid phase penetration than nozzle N1 with-out conicity.
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| 8. |
- Du, Chengjun, 1985, et al.
(författare)
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Effects of Nozzle Geometry on the Characteristics of an Evaporating Diesel Spray
- 2016
-
Ingår i: SAE International Journal of Fuels and Lubricants. - : SAE International. - 1946-3952 .- 1946-3960. ; 9:3, s. 21-
-
Tidskriftsartikel (refereegranskat)abstract
- The effects of nozzle geometry on diesel spray characteristics were studied in a spray chamber under evaporating conditions using three single-hole nozzles, one cylindrical and two convergent, designated N1 (outlet diameter 140 μm, k-factor 0), N2 (outlet diameter140 μm, k-factor 2) and N3 (outlet diameter 136 μm, k-factor 2). Spray experiments were performed with each nozzle at two constant gas densities (15 and 30 kg/m3) and an ambient temperature (673 K) at which evaporation occurs, with injection pressures ranging from 800 to 1600 bar. A light absorption and scattering method using visible and UV light was implemented, and shadow images of liquid and vapor phase fuel were recorded with high-speed video cameras. The cylindrical nozzle N1 yielded larger local vapor cone angles than the convergent nozzles N2 and N3 at both gas densities, and the difference became larger as the injection pressureincreased. The vapor phase penetration values for nozzle N1 and N3 were quite similar and always lower than those for N2. This is consistent with the impingement measurements, which showed that the momentum flux of nozzle N1 was only slightly greater than that of nozzle N3, while that of nozzle N2 was substantially greater. The vapor volume fractions measured along the spray’s center line were well explained by the one-dimensional transient diesel jet model, indicating that diesel spray vaporization is controlled by turbulent fuel-air mixing.
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| 9. |
- Du, Chengjun, 1985, et al.
(författare)
-
Ignition delay, lift-off and soot luminescence in Diesel-ethanol spray combustion
- 2014
-
Ingår i: 6th International Conference on Sustainable Automotive Technologies, 29-30 Sep. 2014, Gothenburg, Sweden..
-
Konferensbidrag (refereegranskat)abstract
- To investigate the influence of ethanol blending in Diesel fuel on the spray combustion characteristics, experiments were carried out in an optically accessed high-pressure / high-temperature spray chamber. Three different fuels were investigated: (1) Diesel, based on the European EN590 standard; (2) E10 with 10% ethanol and (3) E20 with 20% ethanol. Gas conditions were kept at a constant gas density of 24.3 kg/m3 at a lower combusting temperature (550 ºC, 57.3 bar) and a higher combusting temperature (600 ºC, 60 bar). The experimental results showed that ignition delay and delay time of soot formation were increased as ethanol was blended in Diesel fuel. Less soot luminescence was observed and longer lift-off length was measured in Diesel-ethanol blends compared to pure Diesel.
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| 10. |
- Du, Chengjun, 1985, et al.
(författare)
-
Ignition Delay, Lift-off and Soot Luminescence in Diesel-Ethanol Spray Combustion
- 2015
-
Ingår i: Lecture Notes in Mobility. - Cham : Springer International Publishing. - 2196-5544 .- 2196-5552. ; , s. 85-91
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- To investigate the influence of ethanol blending in Diesel fuel on the spray combustion characteristics, experiments were carried out in an optically accessed high-pressure/high-temperature spray chamber. Three different fuels were investigated: (1) Diesel, based on the European EN590 standard; (2) E10 with 10 % ethanol and (3) E20 with 20 % ethanol. Gas conditions were kept at a constant gas density of 24.3 kg/m3 at a lower combusting temperature (550 °C, 57.3 bar) and a higher combusting temperature (600 °C, 60 bar). The experimental results showed that ignition delay and delay time of soot formation were increased as ethanol was blended in Diesel fuel. Less soot luminescence was observed and longer lift-off length was measured in Diesel-ethanol blends compared to pure Diesel.
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| 11. |
- Du, Chengjun, 1985, et al.
(författare)
-
The effect of cavitation on the estimation of fuel injection rates based on momentum flux measurements
- 2019
-
Ingår i: Fuel. - : Elsevier BV. - 0016-2361. ; 238, s. 354-362
-
Tidskriftsartikel (refereegranskat)abstract
- A study was conducted to determine how geometry-induced cavitation affects the reliability of injection rate estimates based on momentum flux measurements. Experiments were performed with two hydro-grinding diesel injector nozzles (Do = 190 µm), one having a cylindrical nozzle orifice that has a strong tendency to induce cavitation, and the other having a convergent nozzle orifice that tends to suppress cavitation. In addition, near-field microscopic images were captured to investigate the influence of cavitation on the liquid jet at the nozzle exit. The momentum flux measurements and near-field imaging were conducted at ambient pressure, using injection pressures of up to 2500 bar. When estimating the injection rate based on momentum flux measurements, failure to account for cavitation caused the integrated injection rate to be overestimated around 9% for the cavitating (cylindrical) nozzle but not for the non-cavitating (convergent) nozzle. We therefore recommend that cavitation should be accounted for when estimating injection rates for cavitating nozzles but not for non-cavitating nozzles. Further, we show that the tendency of a given nozzle orifice to induce cavitation can be evaluated by measuring the nozzle's momentum flux under the assumption of zero cavitation and then comparing the estimated mass of injected fuel to the weighed mass.
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| 12. |
- Du, Chengjun, 1985, et al.
(författare)
-
The Influence of Ethanol Blending in Diesel fuel on the Spray and Spray Combustion Characteristics
- 2014
-
Ingår i: SAE International Journal of Fuels and Lubricants. - : SAE International. - 1946-3952 .- 1946-3960. ; 7(3):November 2014, s. 823-832
-
Tidskriftsartikel (refereegranskat)abstract
- The influence of ethanol blending in Diesel fuel on the spray and spray combustion characteristics was investigated by performing experiments in an optically accessible high-pressure / high-temperature spray chamber under non-evaporating, evaporating and combusting conditions. Three fuels were investigated: (1) Diesel - a European Diesel based on the EN590 standard; (2) E10 - a blend of Diesel containing 10% ethanol and 2% emulsion additive; and (3) E20 - a blend of Diesel containing 20% ethanol and 2% emulsion additive. A constant gas density of 24.3 kg/m3 was maintained under non-evaporating (30 °C, 21.1 bar), evaporating (350 °C, 43.4 bar), low combustion temperature (550 °C, 57.3 bar) and high combustion temperature (600 °C, 60 bar) conditions. A single-hole injector with a nozzle diameter of 0.14 mm was used and injection pressure was held constant at 1350 bar. Various optical methods were used to characterize the non-combusting and combusting sprays.Despite the differences in the fuels' compositions, they did not differ significantly with respect to their liquid phase spray penetrations or cone angles under non-evaporating or evaporating conditions. However, under combusting conditions, reducing the ambient temperature increased the ignition delay and delayed the onset of soot formation for all fuels. Under equivalent combustion conditions, E10 and E20 had longer ignition and soot formation delays than Diesel. As the ethanol content of the fuel was increased from 0% to 20%, the lift-off length increased and the detectable soot luminescence decreased.
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| 13. |
- Du, Chengjun, 1985, et al.
(författare)
-
Time-Resolved Liquid and Vapor Phase Distribution Measurement in Diesel Sprays Using a Light Absorption Scattering Technique
- 2016
-
Ingår i: ILASS – Europe 2016, 27th Annual Conference on Liquid Atomization and Spray Systems, 4-7 September 2016, Brighton, UK.
-
Konferensbidrag (refereegranskat)abstract
- The laser absorption scattering (LAS) technique [Suzuki, et al., 1993, SAE Technical Paper, 930863] is a line-of-sight extinction technique that has several advantages such as high signal-to-noise ratio, low ambient temperature dependence and no fluorescence quenching. However, the LAS technique has been limited to single-shot measurements, which means only one spray image could be captured in one injection event. In order to record the whole vapor phase distribution development in one injection event, a new approach was developed using high-speed video cameras, and n-dodecane with 2% and 10% 1-methylnaphthalene was used as model fuels. Spray imaging was carried out in a spray chamber with temperature varied in the range 423 – 653 K, the ambient pressure was kept constant at 58 bar, and a fuel injection pressure of 800 –1200 bars was applied. It was shown that using UV light and visible light, the detailed liquid and vapor phase distribution development was captured clearly for both 2% 1-MN and 10% 1-MN fuel. Extinction tends to be saturated in UV images with 10% 1-MN fuel at various ambient temperatures. However, with 2% 1-MN fuel, there is no saturation at the applied conditions.
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| 14. |
- Du, Chengjun, 1985, et al.
(författare)
-
Two-dimensional measurements of soot in a turbulent diffusion diesel flame: the effects of injection pressure, nozzle orifice diameter, and gas density
- 2018
-
Ingår i: Combustion Science and Technology. - : Informa UK Limited. - 0010-2202 .- 1563-521X. ; 190:9, s. 1659-1688
-
Tidskriftsartikel (refereegranskat)abstract
- © 2018, Published with license by Taylor & Francis Group, LLC © 2018 [Chengjun Du, Sven Andersson, Mats Andersson]. Two-dimensional light extinction, flame luminosity, and OH* chemiluminescence images were captured at a constant ambient temperature of 823 K and two gas densities (20 and 26 kg/m3), with injection pressures of 800–2500 bar using nozzle orifices with diameters of 0.19 and 0.10 mm. Soot volume fraction and OH distribution images were obtained using the Abel inversion method, and the local equivalence ratio in the lift-off length region was predicted. The results show that the equivalence ratio along the jet’s center at the lift-off length (ϕCL) was found to play a critical role in soot formation. Reductions in ϕCLthickened the OH zone in the upstream region of the jet, reducing the volume corresponding to the maximum soot volume fraction. The expansion of the OH zone also helped reduce the sooting zone’s width. Under high sooting conditions (e.g., ϕCL>3.5), the sooting zone width in the downstream jet was independent of ϕCL.
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| 15. |
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| 16. |
- Lima Ochoterena, Raul, 1978, et al.
(författare)
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Determination of soot size and concentration in optically dense sprays by optical methods
- 2006
-
Ingår i: 10th Conference on Combustion Generated Nanoparticles, 2006. Zurich, 21st -23rd August.
-
Konferensbidrag (refereegranskat)abstract
- The understanding of the formation and oxidation of soot is of interest to become able to reduce the emission of soot particles to the atmosphere from direct injection engines. A possible path to study the formation of soot in diesel sprays is by laser-based optical methods, having the potential for high temporal and spatial resolution; moreover they can be combined to obtain information of soot at any given instant from the start of combustion. Laser Induced Incandescence (LII), Elastic Light Scattering (ELS) and Light Extinction (LE) have been widely used for soot studies [1]. Soot particle size and concentration can be measured simultaneously combining LII, ELS and LE, the combination of these three techniques has proven to be functional when used to measure soot in optically thin flames in atmospheric conditions [2] and exhaust gases [3]. Optically dense systems such as diesel spray combustion, and the diagnostic of soot in them, require special attention to the LII signal because of its strong non-linear dependence on the laser fluence. Moreover particular concern must be given to the enhanced conductive heat transfer term in the LII interpretation due to the high pressure inside the combustion chamber at which diesel engines are usually operated [4]. This paper presents a method to measure particle size and particle concentration in optically dense sprays in conditions similar to those prevailing in real direct injection engines. For this purpose a non-linear compensation method to approximate the laser intensity across optically dense sprays was developed together with a new non-continuum heat transfer model for the LII signal.
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| 17. |
- Lindsay, Willow, 1980, et al.
(författare)
-
Endless forms of sexual selection
- 2019
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Ingår i: PeerJ. - : PeerJ. - 2167-8359. ; 7
-
Tidskriftsartikel (refereegranskat)abstract
- In recent years, the field of sexual selection has exploded, with advances in theoretical and empirical research complementing each other in exciting ways. This perspective piece is the product of a "stock-taking'' workshop on sexual selection and sexual conflict. Our aim is to identify and deliberate on outstanding questions and to stimulate discussion rather than provide a comprehensive overview of the entire field. These questions are organized into four thematic sections we deem essential to the field. First we focus on the evolution of mate choice and mating systems. Variation in mate quality can generate both competition and choice in the opposite sex, with implications for the evolution of mating systems. Limitations on mate choice may dictate the importance of direct vs. indirect benefits in mating decisions and consequently, mating systems, especially with regard to polyandry. Second, we focus on how sender and receiver mechanisms shape signal design. Mediation of honest signal content likely depends on integration of temporally variable social and physiological costs that are challenging to measure. We view the neuroethology of sensory and cognitive receiver biases as the main key to signal form and the 'aesthetic sense' proposed by Darwin. Since a receiver bias is sufficient to both initiate and drive ornament or armament exaggeration, without a genetically correlated or even coevolving receiver, this may be the appropriate 'null model' of sexual selection. Thirdly, we focus on the genetic architecture of sexually selected traits. Despite advances in modern molecular techniques, the number and identity of genes underlying performance, display and secondary sexual traits remains largely unknown. In-depth investigations into the genetic basis of sexual dimorphism in the context of long-term field studies will reveal constraints and trajectories of sexually selected trait evolution. Finally, we focus on sexual selection and conflict as drivers of speciation. Population divergence and speciation are often influenced by an interplay between sexual and natural selection. The extent to which sexual selection promotes or counteracts population divergence may vary depending on the genetic architecture of traits as well as the covariance between mating competition and local adaptation. Additionally, post-copulatory processes, such as selection against heterospecific sperm, may influence the importance of sexual selection in speciation. We propose that efforts to resolve these four themes can catalyze conceptual progress in the field of sexual selection, and we offer potential avenues of research to advance this progress.
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| 18. |
- Magnusson, Alf, 1958, et al.
(författare)
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A Comparison of Spray Properties for Model Fuel and Diesel Using Several Optical Methods
- 2004
-
Ingår i: 19th Ilass Europe.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Many experiments are carried out using a model fuel, for instance for measurement technique reasons. These data are usually transferred to situations where standard diesel fuel is used. The objective of this work is to characterize the liquid and vapour phase penetration of two different diesel fuels, one two-component model fuel, IDEA (70% n-decane and 30% α-methylnaphthalene) and one standard diesel fuel (Swedish Environmental Class I), when injected into air with density corresponding to early injections up to self ignition conditions in diesel engines. The experimental study was carried out in the high-pressure, high-temperature (HP/HT) spray rig at Chalmers, which was pressurized in the range of 4 to 85 bar and with temperature ranging from 400 to 800 K.A common-rail injection system with a single hole nozzle was used. Several optical methods (Schlieren, Shadowgraph, LIF (Laser Induced Fluorescence) and Mie-scattering) were used together or separately which allow a comparison of the output. Phase Doppler Anemometry (PDA) was used for the two fuels as a complement to the planar methods. Results from measurements show that there are differences in liquid penetration, fuel vaporization and droplet distribution in between the fuels and relatively good agreement between the methods
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| 19. |
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| 20. |
- Ochoterena, Raul, et al.
(författare)
-
Apparent Soot Size and Concentration in Combusting Diesel Jets at High Gas Pressures and Temperatures Measured by Combining Quasi-Simultaneous LII, Elastic Light Scattering and Light Extinction
- 2020
-
Ingår i: SAE technical paper series. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191 .- 2688-3627. ; 2:3, s. 1578-1591
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Tidskriftsartikel (refereegranskat)abstract
- A method for measuring apparent soot particle size and concentration in turbulent combusting diesel jets with elevated and inhomogeneous optical density is presented and discussed. The method is based on the combination of quasi-simultaneous Laser Induced Incandescence (LII), Elastic Scattering (ELS) and Light Extinction (LE) measurements exhibiting a high potential for spatially resolved measurements of carbonaceous particles in flames and residual gases at a given instant. The method evaluates the LII signal by calculating the laser fluence across the flame and compensating for signal trapping, allowing measurements where laser extinction between the flame borders reaches values up to 90 %. The method was implemented by measuring particle size and concentration in the middle sagittal axis of optically dense, combusting diesel jets at a certain time after the start of combustion. Experiments were carried out in the Chalmers High Pressure, High Temperature spray rig under conditions similar to those prevailing in direct injected compression ignition engines. Measurements of apparent particle size and concentration together with volume fraction conferring an instantaneous single-shot case and an average measurement from several consecutive jets are presented and discussed.
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| 21. |
- Otxoterena Af Drake, Paul, et al.
(författare)
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Two Dimensional Measurements of Soot Size and Concentration in Diesel Flames by Laser Based Optical Methods
- 2022
-
Ingår i: <em>SAE Technical Paper </em>Issue 202229 March 2022. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International.
-
Konferensbidrag (refereegranskat)abstract
- Soot particle size, particle concentration and volume fraction were measured by laser based methods in optically dense, highly turbulent combusting diesel sprays under engine-like conditions. Experiments were done in the Chalmers High Pressure, High Temperature spray rig under isobaric conditions and combusting commercial diesel fuel. Laser Induced Incandescence (LII), Elastic Scattering and Light Extinction were combined quasi-simultaneously to quantify particle characteristics spatially resolved in the middle plane of a combusting spray at two instants after the start of combustion. The influence that fuel injection pressure, gas temperature and gas pressure exert on particle size, particle concentration and volume fraction were studied. Probability density functions of particle size and two-dimensional images of particle diameter, particle concentration and volume fraction concerning instantaneous single-shot cases and average measurements are presented. High injection pressure led to a reduction in the mean particle size, total number of particles and total amount of soot compared to a low injection pressure. Higher gas pressure resulted in larger amount of soot and larger soot particle size, with higher gas temperature having similar effects.
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| 22. |
- Torstensson, Anders, et al.
(författare)
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Synergism between elevated pCO2 and temperature on the Antarctic sea ice diatom Nitzschia lecointei
- 2013
-
Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 10, s. 6391-6401
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Tidskriftsartikel (refereegranskat)abstract
- Polar oceans are particularly susceptible to ocean acidification and warming. Diatoms play a significant role in sea ice biogeochemistry and provide an important food source to grazers in ice-covered oceans, especially during early spring. However, the ecophysiology of ice-living organisms has received little attention in terms of ocean acidification. In this study, the synergism between temperature and partial pressure of CO2 (pCO2) was investigated in relationship to the optimal growth temperature of the Antarctic sea ice diatom Nitzschia lecointei. Diatoms were kept in cultures at controlled levels of pCO2 (∼390 and ∼960 μatm) and temperature (−1.8 and 2.5 °C) for 14 days. Synergism between temperature and pCO2 was detected in growth rate and acyl lipid fatty acid (FA) content. Optimal growth rate was observed around 5 °C in a separate experiment. Carbon enrichment only promoted (6%) growth rate closer to the optimal growth, but not at the control temperature (−1.8 °C). At −1.8 °C and at ∼960 μatm pCO2, the total FA content was reduced relative to the ∼390 μatm treatment, although no difference between pCO2 treatments was observed at 2.5 °C. A large proportion (97%) of the total FAs comprised on average of polyunsaturated fatty acids (PUFA) at −1.8 °C. Cellular PUFA content was reduced at ∼960 relative to ∼390 μatm pCO2. Effects of carbon enrichment may be different depending on ocean warming scenario or season, e.g. reduced cellular FA content in response to elevated CO2 at low temperatures only, reflected as reduced food quality for higher trophic levels. Synergy between warming and acidification may be particularly important in polar areas since a narrow thermal window generally limits cold-water organisms.
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| 23. |
- Adman, Per, et al.
(författare)
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171 forskare: ”Vi vuxna bör också klimatprotestera”
- 2019
-
Ingår i: Dagens nyheter (DN debatt). - Stockholm. - 1101-2447.
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- DN DEBATT 26/9. Vuxna bör följa uppmaningen från ungdomarna i Fridays for future-rörelsen och protestera eftersom det politiska ledarskapet är otillräckligt. Omfattande och långvariga påtryckningar från hela samhället behövs för att få de politiskt ansvariga att utöva det ledarskap som klimatkrisen kräver, skriver 171 forskare i samhällsvetenskap och humaniora.
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| 24. |
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| 25. |
- Agrawal, Tarun, 1989, et al.
(författare)
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Automating Loading and Unloading for Autonomous Transport: Identifying Challenges and Requirements with a Systems Approach
- 2023
-
Ingår i: IFIP Advances in Information and Communication Technology. - 1868-4238 .- 1868-422X. - 9783031436697 ; 691 AICT, s. 332-345
-
Konferensbidrag (refereegranskat)abstract
- The logistics industry has undergone significant changes due to high demand, competition, cost pressures, interruptions, and labor market limitations affecting supply chains. As a result, there has been a significant adoption of automation in internal logistics such as warehousing, stock control, and material handling, leading to increased organizational competitiveness by reducing manual labor costs and time spent on these operations. The use of autonomous road transport holds potential to improve transport performance within areas of safety, sustainability, and efficiency. However, for autonomous transport to be fully ealized, loading and unloading processes at shipping and receiving facilities must also be automated. This paper takes a systems approach to identify the challenges and requirements for automated loading and unloading in a setting of autonomous truck transport potentially within a production setting. By addressing these challenges and meeting the necessary requirements, it may be possible to fully realize the benefits of autonomous transport and improve overall transport performance.
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| 26. |
- Andersson, Agneta, et al.
(författare)
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Microbial food web changes induced by terrestrial organic matter and elevated temperature in the coastal northern Baltic Sea
- 2023
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Ingår i: Frontiers in Marine Science. - : Frontiers Media S.A.. - 2296-7745. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- Climate change has been projected to cause increased temperature and amplified inflows of terrestrial organic matter to coastal areas in northern Europe. Consequently, changes at the base of the food web favoring heterotrophic bacteria over phytoplankton are expected, affecting the food web structure. We tested this hypothesis using an outdoor shallow mesocosm system in the northern Baltic Sea in early summer, where the effects of increased temperature (+ 3°C) and terrestrial matter inputs were studied following the system dynamics and conducting grazing experiments. Juvenile perch constituted the highest trophic level in the system, which exerted strong predation on the zooplankton community. Perch subsequently released the microbial food web from heavy grazing by mesozooplankton. Addition of terrestrial matter had a stronger effect on the microbial food web than the temperature increase, because terrestrial organic matter and accompanying nutrients promoted both heterotrophic bacterial production and phytoplankton primary production. Moreover, due to the shallow water column in the experiment, terrestrial matter addition did not reduce the light below the photosynthesis saturation level, and in these conditions, the net-autotrophy was strengthened by terrestrial matter enrichment. In combination with elevated temperature, the terrestrial matter addition effects were intensified, further shifting the size distribution of the microbial food web base from picoplankton to microphytoplankton. These changes up the food web led to increase in the biomass and proportion of large-sized ciliates (>60 µm) and rotifers. Despite the shifts in the microbial food web size structure, grazing experiments suggested that the pathway from picoplankton to nano- and microzooplankton constituted the major energy flow in all treatments. The study implies that the microbial food web compartments in shallow coastal waters will adjust to climate induced increased inputs of terrestrial matter and elevated temperature, and that the major energy path will flow from picoplankton to large-sized ciliates during the summer period.
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| 27. |
- Andersson, Dan, 1966, et al.
(författare)
-
Wave-breaking-free pulses in nonlinear-optical fibers
- 1993
-
Ingår i: Journal of the Optical Society of America B: Optical Physics. - 1520-8540 .- 0740-3224. ; 10:7, s. 1185-1190
-
Tidskriftsartikel (refereegranskat)abstract
- A qualitative as well as quantitative investigation is made of the conditions for avoiding wave breaking during pulse propagation in optical fibers. In particular, it is shown that pulses having a parabolic intensity variation are approximate wave-breaking-free solutions of the nonlinear Schrodinger equation in the high-intensity limit. A simple expression for the compression factor of a fiber-grating compressor based on parabolic pulses is also derived.
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| 28. |
- Andersson, Fredrik, et al.
(författare)
-
A Portable Douglas Bag System
- 2015
-
Ingår i: Congress Proceedings. - 9789513962166 ; , s. 59-
-
Konferensbidrag (refereegranskat)
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| 29. |
- Andersson, Mats, 1963, et al.
(författare)
-
Adsorption and reactions of O2 and D2 on small free palladium clusters in a cluster-molecule scattering experiment
- 2010
-
Ingår i: Journal of Physics Condensed Matter. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 22:33, s. 334223-
-
Tidskriftsartikel (refereegranskat)abstract
- The adsorption of oxygen and hydrogen (deuterium) on small neutral palladium clusters was investigated in a cluster beam experiment. The beam passes through two low-pressure reaction cells, and the clusters, with and without adsorbed molecules, are detected using laser ionization and mass spectrometry. Both H2 and O2 adsorb efficiently on the palladium clusters with only moderate variations with cluster size in the investigated range, i.e. between 8 and 28 atoms. The co-adsorption of H2 and O2 results in the formation of H2O, detected as a decrease in the number of adsorbed oxygen atoms with an increasing number of collisions with H2 molecules. A comparison is done with an earlier similar study of clusters of Pt. Furthermore a comparison is done with what is known for sticking and reactivity of surfaces.
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| 30. |
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| 31. |
- Andersson, Mats, 1963, et al.
(författare)
-
Application of laser-induced fluorescence for imaging of model fuels emulating gasoline and gasoline/ethanol blends
- 2009
-
Ingår i: Proceedings of ICLASS 2009, 11th International Congress on Liquid Atomization and Spray Systems. ; , s. ICLASS2009-189
-
Konferensbidrag (refereegranskat)abstract
- The performance at cold start of spark-ignited car engines is still a challenge since slow and incomplete vaporization of the fuel causes high emissions of unburned hydrocarbons and may even cause difficulties to start at very low temperatures, in particular with alternative fuels such as ethanol. One approach to improve fuel evaporation is by direct injection into the cylinder late during the compression stroke. In this study the evaporation of fuel, including selective evaporation of fuel components of different volatility, has been studied, in sprays injected into air with a controlled pressure and temperature. Planar laser-induced fluorescence (PLIF) and Mie scattering were used to image the fuel distribution in vapor and liquid phase in a cross-section of sprays. A model fuel of non-fluorescent molecules was used and a fluorescent tracer molecule was added. To simulate a fuel with a distillation curve similar to gasoline a multi-component model fuel was selected. The fuel was composed of five iso- or cyclo-alkenes with boiling points that span the 30-190°C range. As fluorescence tracers ketones: acetone, 3-pentanone and methylcyclohexanone, were used to trace light, medium-heavy and heavy fuel fractions. Besides investigating the gasoline-like model fuel, ethanol and an etha-nol/multi-components fuel blend were investigated. Spray imaging was carried out in a pressurized chamber. The injector was an outward-opening piezo-actuated injector generating a hollow-cone spray. A cross-section of the spray was illuminated by laser light at a wavelength of 266 nm formed into a thin sheet. Two intensified CCD-cameras were used to detect fluorescence and scattered light. The presence and penetration of liquid was determined by detecting Mie-scattered light. The PLIF-images provided the total distribution of fuel in liquid and vapor phase, and by comparing with the Mie-images it could be determined when the vapor started to appear in areas with little or no drops present indicating the presence of fuel vapor. It was found that at 90°C the light fuel components evaporated quickly, the medium-heavy components slowly while the heavy ones remained in liquid phase. At 140°C also the medium-heavy components evaporate relatively rapidly.
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| 32. |
- Andersson, Mats, 1963, et al.
(författare)
-
Application of laser-induced fluorescence for imaging sprays of model fuels emulating gasoline and gasoline/ethanol blends
- 2009
-
Ingår i: 11th International Annual Conference on Liquid Atomization and Spray Systems 2009, ICLASS 2009. - 9781617826535
-
Konferensbidrag (refereegranskat)abstract
- The performance at cold start of spark-ignited car engines is still a challenge since slow and incomplete vaporization of the fuel causes high emissions of unburned hydrocarbons and may even cause difficulties to start at very low temperatures, in particular with alternative fuels such as ethanol. One approach to improve fuel evaporation is by direct injection into the cylinder late during the compression stroke. In this study the evaporation of fuel, including selective evaporation of fuel components of different volatility, has been studied, in sprays injected into air with a controlled pressure and temperature. Planar laser-induced fluorescence (PLIF) and Mie scattering were used to image the fuel distribution in vapor and liquid phase in a cross-section of sprays. A model fuel of non-fluorescent molecules was used and a fluorescent tracer molecule was added. To simulate a fuel with a distillation curve similar to gasoline a multi-component model fuel was selected. The fuel was composed of five iso- or cyclo-alkenes with boiling points that span the 30-190°C range. As fluorescence tracers ketones: acetone, 3-pentanone and methylcyclohexanone, were used to trace light, medium-heavy and heavy fuel fractions. Besides investigating the gasoline-like model fuel, ethanol and an ethanol/multi-components fuel blend were investigated. Spray imaging was carried out in a pressurized chamber. The injector was an outward-opening piezo-actuated injector generating a hollow-cone spray. A cross-section of the spray was illuminated by laser light at a wavelength of 266 nm formed into a thin sheet. Two intensified CCD-cameras were used to detect fluorescence and scattered light. The presence and penetration of liquid was determined by detecting Mie-scattered light. The PLIF-images provided the total distribution of fuel in liquid and vapor phase, and by comparing with the Mie-images it could be determined when the vapor started to appear in areas with little or no drops present indicating the presence of fuel vapor. It was found that at 90°C the light fuel components evaporated quickly, the medium-heavy components slowly while the heavy ones remained in liquid phase. At 140°C also the medium-heavy components evaporate relatively rapidly.
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| 33. |
- Andersson, Mats, 1963, et al.
(författare)
-
Evaporation of Gasoline-Like and Ethanol-Based Fuels in Hollow-Cone Sprays Investigated by Planar Laser-Induced Fluorescence and Mie Scattering
- 2011
-
Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191 .- 2688-3627. ; , s. 2011-01-1889-
-
Tidskriftsartikel (refereegranskat)abstract
- The evaporation of different fuels and fuel components in hollow-cone sprays at conditions similar to those at stratified cold start has been investigated using a combination of planar laser-induced fluorescence (LIF) and Mie scattering. Ketones of different volatility were used as fluorescent tracers for different fuel components in gasoline-like model fuels and ethanol-based fuels. LIF and Mie images were compared to evaluate to what extent various fuel components had evaporated and obtained a spatial distribution different from that of the liquid drops, as a function of fuel temperature and time after start of injection. A selective and sequential evaporation of fuel components of different volatility was found.
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| 34. |
- Andersson, Mats, 1963, et al.
(författare)
-
Evaporation of gasoline-like sprays from an outwards-opening injector studied with LIEF
- 2017
-
Ingår i: COMODIA 2017 - 9th International Conference on Modeling and Diagnostics for Advanved Engine Systems. - : Japan Society of Mechanical Engineers.
-
Konferensbidrag (refereegranskat)abstract
- The design and operation of the fuel injection system plays an important role to achieve a suitable fuel distribution in the cylinder. The liquid fuel should evaporate and mix well with air, and avoid overly rich or lean zones as well as wall and piston wetting. Spray imaging in a constant-volume, constant-pressure chamber, provides a well-controlled environment for detailed characterization of spray development under different operational conditions. In this study planar laser-induced exciplex fluorescence is used since it enables separate imaging of both vapor and liquid phase of fuel simultaneously. As a surrogate fuel for gasoline n-hexane is used with fluorobenzene and diethylmethylamine added as exciplex-forming tracers. Fluorescence excitation is carried out with a parallel laser sheet from the fourth harmonic light of a Nd: YAG-laser (266 nm). Exciplex fluorescence images from liquid phase and monomer fluorescence images from vapor phase can be acquired by a single UV-sensitive CMOS camera equipped with a stereoscope having filters selectively transmitting monomer fluorescence at 295 nm and exciplex fluorescence at 355 nm. Sprays from an outwards-opening injector with an initial hollow-cone shape were investigated at gas pressures above atmospheric. The expanding conical fuel sheet breaks up and a torus-shaped vortex structure is formed with the vortices continuing to expand after the end of injection, which is the typical development using this type of injector. Fuel vapor is firstly observed at the same locations as the liquid drops, and is then accumulated into the center of the vortices. The fuel evaporation was found to be very slow at room temperature, whereas the vapor fraction was significant already at the end of injection above 40°C, and an even faster evaporation was observed above 55°C.
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| 35. |
- Andersson, Mats, 1963, et al.
(författare)
-
Imaging of Gasoline-like Sprays with Planar Laser-induced Exciplex Fluorescence using a Stereoscopic Imaging System
- 2017
-
Ingår i: 28th Conference on Liquid Atomization and Spray Systems, ILASS-EUROPE 2017. ; , s. 546-552
-
Konferensbidrag (refereegranskat)abstract
- The role of the fuel injection systems in direct injected gasoline engines is to achieve a suitable fuel vapor distribution, homogeneous or with some degree of stratification, while avoiding unwanted effects such as wall wetting. Planar laser-induced exciplex fluorescence (PLIEF) is a method suitable for the characterization of such sprays since it enables separate imaging of both vapor and liquid phase of fuel simultaneously. In this study a hollow-cone spray generated with an outwards-opening piezo-actuated injector is investigated, with the injector mounted in a constant volume, constant pressure spray chamber with quartz windows, providing a controlled steady test environment. N-hexane is used as surrogate fuel of gasoline, together with exciplex-forming fluorescence tracers - fluorobenzene and diethylmethylamine. Fluorescence excitation is carried out with a parallel laser sheet from the fourth harmonic light of a Nd:YAG-laser (266 nm) running at 10 Hz. Exciplex fluorescence images from liquid phase and monomer fluorescence spray images from vapor phase can be acquired by a single UV-sensitive CMOS camera equipped with a stereoscope having filters selectively transmitting monomer fluorescence at 295 nm and exciplex fluorescence at 355 nm. Since the fluorescence is strongly quenched by oxygen, most of the experiments were carried out in a nitrogen atmosphere. Images were recorded during the injection and at various time steps after the end of the injection, and typical spray development for this type of injector was observed, i.e. the fuel forms an expanding cone, the sheet breaks up to form a vortex structure and the vortices continue to expand after the end of the injection. Fuel vapor is firstly observed at the same locations as the liquid drops, and is then accumulated into the center of the vortices. In addition, penetration of liquid phase and vapor phase are found to be very similar. Various injection pressures have been tested, which shows that increasing the fuel pressure from 10 to 20 MPa results in a larger vortex structure. The fuel evaporation can be followed by studying the evolution of the monomer and exciplex fluorescence as a function of time. At room temperature the vaporization is found to be very slow, but above 40°C there is a noticeable presence of vapor at the end of the injection, and at higher temperatures, the vaporization goes even faster.
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| 36. |
- Andersson, Mats, 1963
(författare)
-
Metal Cluster Reactivity. Adsorption of small molecules in biomolecular collisions
- 1995
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Metal clusters can be characterized as the tiniest possible metal particles, containing only an easily counted number of atoms. In this work, reactions between metal clusters and diatomic molecules have been investigated. We have constructed an experimental set-up to produce and detect clusters, and to investigate their chemical reactivity. A pulsed beam of neutral metal clusters is generated in a laser vaporization source. After skimming, the cluster beam enters a second vacuum chamber where the clusters are ionized with laser light and detected with time-of-flight mass spectrometry. In the reactivity experiments, the cluster beam passes a cell containing low pressure reactive gas. The clusters can make one or a few collisions with the molecules and in the mass spectrometric detection the amount of reaction products, clusters with adsorbed molecules, is measured. Thus, the reaction probability in a collision can be evaluated. If several molecules are adsorbed, the reaction probability in the following reaction steps can also be evaluated. Using this method, the adsorption of various diatomic molecules onto clusters of several metals has been investigated. Size-dependent reaction probabilities have been determined for clusters in the approximate size range 10-50 atoms. The O2 reaction probability of transition metal clusters appears to be relatively low on small clusters and increases with size up to 15-20 atoms where it levels off at a high value (0.5-1.0). The lower reactivity for the smaller clusters is thought to be an effect of the highly exothermic reaction which can induce fragmentation preferentially for small clusters. Copper clusters show a lower O2 reactivity with repeated maxima and minima. The minima in reactivity appear at clusters with closed electronic shells, according to the jellium model. The interpretation of this reaction was supported by a theoretical analysis of O2 adsorption on Cu-jellium clusters. We have also measured how the ionization potentials of the Cun clusters change after reaction and found that the shell structure, observed for the pure clusters, was depleted, but the even-odd variations persisted. The CO reactivity also showed a simple size dependence for clusters of several metals, with the exception of small Nb clusters. The D2 reactivity characteristics varied from metal to metal, ranging from high reactivity and moderate size variation on Rhsub>n, to rather low reactivity with distinct size dependence for Con, to Cun which appeared to be unreactive.
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| 37. |
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| 38. |
- Andersson, Mats, 1963, et al.
(författare)
-
Temperature measurements using exciplex fluorescence with TMPD and methylnaphthalene as tracers
- 2008
-
Ingår i: Proc. 22nd European Conference on Liquid Atomization and Spray Systems. - 9788890371202 ; , s. ILASS-08-P-19-
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Laser-induced exciplex fluorescence has been used to measure the temperature in a spray of a diesel-like fuel. To a model fuel consisting of 70 % n-decane and 30 % 1-methylnaphthalene, TMPD was added in a concentration of 0.2 %. When excited with UV-light TMPD efficiently forms an exciplex with methylnaphthalene fluorescing with a peak intensity at a wavelength around 505 nm at room temperature. When the temperature of the fuel increases the peak position shifts to shorter wavelengths, and the peak reaches a position of 475 nm at 150 ºC. This shift of the fluorescence spectrum can be used to estimate the temperature of the liquid fuel, by measuring the fluorescence light intensity in two different wavelength intervals and evaluate the ratio between them as a function of temperature. The intensity ratio as a function of temperature was evaluated and calibrated, and subsequently used to determine the temperature of the liquid fuel along the spray axis.
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| 39. |
- Andersson-Sköld, Yvonne, 1957, et al.
(författare)
-
Microplastics from tyre and road wear: a literature review
- 2020
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This literature review concerns microplastics from tyre and road wear caused by road traffic. As there is limited knowledge about microplastics in general, and microplastics from road traffic in particular, the Swedish Government commissioned the Swedish National Road and Transport Research Institute (VTI) to, during 2018-2020, develop and disseminate knowledge about microplastics from road traffic. The chapters in this report summarises existing knowledge about microplastics from road traffic with respect to the following aspects: sources, spread and presence; effects on and risk to the environment and human health; characteristics and chemical composition; tyre and road wear; sampling methods; analysis and sample preparation; and measures. The report also includes a chapter with overall conclusions, and a chapter about further research, development and investigation needs. The purpose of this report is to provide a basis for reducing the generation and spread of microplastics from road traffic. One aim of the report is to collate and disseminate knowledge about microplastics generated by tyre and road wear, and to review the current level of knowledge. A second aim is to identify knowledge gaps and research requirements in relation to microplastics from road traffic. This literature review is based on a review of scientific articles and reports, as well as technical literature and some information from experts and industry.
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| 40. |
- Andersson-Sköld, Yvonne, 1957-, et al.
(författare)
-
Mikroplast från däck- och vägslitage : en kunskapssammanställning
- 2020
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Denna kunskapssammanställning handlar om mikroplast från vägtrafikens däck- och vägslitage. Eftersom kunskapen om mikroplaster från vägtrafiken är begränsad samtidigt som däckslitage bedöms vara den största källan till utsläpp av mikroplast i Sverige, gav regeringen inom ramen för sitt arbete med plast och mikroplast Statens väg- och transportforskningsinstitut (VTI) i uppdrag att under 2018– 2020 ta fram och sprida kunskap om mikroplast från vägtrafiken. Varje kapitel i denna rapport sammanfattar befintlig kunskap om mikroplast från vägtrafiken avseende en eller flera aspekter. Dessa aspekter är: källor, spridning och förekomst; miljö- och hälsoeffekter samt risker; egenskaper och kemisk sammansättning; däck- och vägslitage; provtagningsmetoder; analys- och provberedningsmetoder samt åtgärder. Dessutom finns ett kapitel med sammanfattande slutsatser och allra sist ett kapitel om forsknings-, utvecklings- och utredningsbehov.Syftet med rapporten är att den ska utgöra ett underlag för att minska emissioner och spridning av mikroplast från vägtrafiken. Ett mål med rapporten är att sammanställa och sprida kunskap om mikroplast från däck- och vägslitage och att redogöra för nuvarande kunskapsläge. Ytterligare ett mål är att identifiera kunskaps- och forskningsbehov avseende mikroplast från vägtrafiken.Underlaget till denna kunskapssammanställning utgörs av vetenskapliga artiklar och rapporter samt facklitteratur och information från branschen och från experter.
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| 41. |
- Ankarberg-Lindgren, Carina, 1963, et al.
(författare)
-
Determination of estrone sulfate, testosterone, androstenedione, DHEAS, cortisol, cortisone, and 17 alpha-hydroxyprogesterone by LC-MS/MS in children and adolescents
- 2020
-
Ingår i: Scandinavian Journal of Clinical & Laboratory Investigation. - : Informa UK Limited. - 0036-5513 .- 1502-7686. ; 80:8, s. 672-680
-
Tidskriftsartikel (refereegranskat)abstract
- Quantitation of endogenous steroids and their precursors is essential for diagnosis of a wide range of endocrine disorders. Usually, these analyses have been carried out using immunoassays. However, immunoassays often overestimate concentrations due to assay interference by other endogenous steroids, especially for low concentrations. Mass spectrometry based methods offer superior specificity, accuracy, and sensitivity. We therefore present a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method with automated sample preparation for determination of 17 alpha-hydroxyprogesterone (17OHP), cortisol, cortisone, dehydroepiandrosterone sulfate (DHEAS), androstenedione (A(4)), testosterone (T), and estrone sulfate (E1S). Samples were prepared using protein precipitation and 96-well filter plates, fully automated in a pipetting robot and analyzed by LC-MS/MS. Serum samples from 187 healthy children and adolescents aged 5-18 years were used to study hormone changes in relation to sex and pubertal stage. Lower limit of quantification for 17OHP was 0.7 nmol/L, for cortisol 11 nmol/L, for cortisone 2 nmol/L, for DHEAS 0.1 mu mol/L, and for A(4), T, and E1S, 0.2 nmol/L. This study showed a general increase in 17OHP, DHEAS, A(4), T and E1S in both genders during puberty. In boys, A(4)and T increased significantly throughout pubertal development. Girls had significantly higher A(4)and E1S concentrations, while boys had higher T concentrations. No sex- or puberty-specific differences were seen in cortisol or cortisone concentrations. To the best of our knowledge, this is the first presentation of changes in serum E1S concentrations during pubertal development in healthy children.
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| 42. |
- Ankarberg-Lindgren, Carina, 1963, et al.
(författare)
-
High-sensitivity quantification of serum androstenedione, testosterone, dihydrotestosterone, estrone and estradiol by gas chromatography-tandem mass spectrometry with sex- and puberty-specific reference intervals.
- 2018
-
Ingår i: The Journal of steroid biochemistry and molecular biology. - : Elsevier BV. - 1879-1220 .- 0960-0760. ; 183, s. 116-124
-
Tidskriftsartikel (refereegranskat)abstract
- Androgen and estrogen determinations serve as important diagnostic markers in a variety of clinical conditions. However, one challenge is to enhance assay sensitivity for determination in the lowest range, such as in prepubertal children. We here present a recently developed gas chromatography-tandem mass spectrometry (GC-MS/MS) method for determination of androstenedione (A4), dihydrotestosterone (DHT), testosterone (T), estrone (E1), and estradiol (E2) in children, which we have compared with the sensitive radioimmunoassays; E2 extraction-RIA and T-RIA.Steroids were extracted in ethyl acetate n-hexane solution from serum spiked with isotopically labeled internal standard and derivatized sequentially with pentafluorobenzyl bromide, pentafluorobenzyl hydroxylamine and pentafluoropropionic acid anhydride and analyzed by GC-MS/MS using a triple quadrupole mass spectrometer operated in negative chemical ionization mode. Leftover routine samples (n=414) were used to evaluate the concordance between GC-MS/MS and RIAs and the validity of GC-MS/MS for pediatrics; of these samples, 101 were from seemingly healthy children. Pubertal stage was recorded for reference interval evaluation.Lower limit of detection for A4, T, DHT, E1, and E2 were 0.1nmol/L, 0.1nmol/L, 27pmol/L, 9pmol/L, and 2pmol/L, respectively. Good agreement was found between GC-MS/MS and T-RIA (r=0.98) as well as between GC-MS/MS and E2 extraction-RIA (r=0.98, for E2 concentrations above 14pmol/L). In boys, T and DHT increased significantly from prepuberty throughout pubertal development, and in girls the same increase was observed for E1 and E2. The greatest increase in A4 for both genders, as well as E1 and E2 in boys and T and DHT in girls, occurred in mid to late puberty.We report the development of a GC-MS/MS method sensitive enough to accurately determine serum levels of androgens and estrogens in children.
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| 43. |
- Avdovic, Pajazit, 1955, et al.
(författare)
-
Evaluating the machinability of Inconel 718 using polar diagrams
- 2010
-
Ingår i: Proceedings of the ASME Turbo Expo 2010: Power for Land, Sea, and Air, GT 2010, Glasgow, United Kingdom, 14-18 June 2010. - 9780791843963 ; 1, s. 987-996
-
Konferensbidrag (refereegranskat)abstract
- The use of a polar diagram method for describing and evaluating the machinability of Inconel 718 was explored. Five key parameters of the work material, representing the mechanical and physical properties which have strongest influence on its machinability, were employed in the diagrams. These five parameters were integrated into a single polar diagram, used to describe the machinability of Inconel 718. Variations in the machinability of Inconel 718 products or components of a given type produced in different batches were analyzed. Industrial experiments were conducted to test the relationship between the polar diagram of the work material, its carbon content, and tool wear of the ceramic cutting tools used in machining it. Work materials of Inconel 718 in which the polar diagrams of machinability were similar in size and shape exhibited very similar behavior during the cutting process. The polar diagram method employed appeared to be useful for selecting suitable cutting data for the machining of new materials.
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| 44. |
- Bempedelis, Nikolaos, et al.
(författare)
-
Numerical and experimental investigation into the dynamics of a bubble-free-surface system
- 2021
-
Ingår i: Physical Review Fluids. - 2469-990X. ; 6:1
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of the present work is to study the interaction between an oscillating bubble and a free surface. We perform a series of experiments and numerical simulations and attempt to characterize both early and late stages of the interaction. The focus is on providing insight into the mechanisms of bubble-induced atomization. For this reason, we are particularly interested in characterizing the patterns and dynamics of the liquid jets that are formed at the free surface. Observations regarding the evolution of the free surface are presented by measuring the jet's surface area and volume. Finally, based on these quantities, we introduce a metric that may be used to characterize the liquid jetting and predict whether late-time atomization of the interface will occur.
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| 45. |
- Berglund, Åsa M. M., 1978-, et al.
(författare)
-
Effects on the food-web structure and bioaccumulation patterns of organic contaminants in a climate-altered Bothnian Sea mesocosms
- 2023
-
Ingår i: Frontiers in Marine Science. - : Frontiers Media S.A.. - 2296-7745. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- Climate change is expected to alter global temperature and precipitation patterns resulting in complex environmental impacts. The proposed higher precipitation in northern Scandinavia would increase runoff from land, hence increase the inflow of terrestrial dissolved organic matter (tDOM) in coastal regions. This could promote heterotrophic bacterial production and shift the food web structure, by favoring the microbial food web. The altered climate is also expected to affect transport and availability of organic micropollutants (MPs), with downstream effects on exposure and accumulation in biota. This study aimed to assess climate-induced changes in a Bothnian Sea food web structure as well as bioaccumulation patterns of MPs. We performed a mesocosms-study, focusing on aquatic food webs with fish as top predator. Alongside increased temperature, mesocosm treatments included tDOM and MP addition. The tDOM addition affected nutrient availability and boosted both phytoplankton and heterotrophic bacteria in our fairly shallow mesocosms. The increased tDOM further benefitted flagellates, ciliates and mesozooplankton, while the temperature increase and MP addition had minor effect on those organism groups. Temperature, on the other hand, had a negative impact on fish growth and survival, whereas tDOM and MP addition only had minor impact on fish. Moreover, there were indications that bioaccumulation of MPs in fish either increased with tDOM addition or decreased at higher temperatures. If there was an impact on bioaccumulation, moderately lipophilic MPs (log Kow 3.6 - 4.6) were generally affected by tDOM addition and more lipophilic MPs (log Kow 3.8 to 6.4) were generally affected by increased temperature. This study suggest that both increased temperatures and addition of tDOM likely will affect bioaccumulation patterns of MPs in shallow coastal regions, albeit with counteracting effects.
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| 46. |
- Berntsson, Andreas, 1978, et al.
(författare)
-
A LIF-study of OH in the Negative Valve Overlap of a Spark-assisted HCCI Combustion Engine
- 2008
-
Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191 .- 2688-3627.
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Tidskriftsartikel (refereegranskat)abstract
- Future requirements for emission reduction from combustionengines in ground vehicles might be met byusing the HCCI combustion concept. In this study,negative valve overlap (NVO) and low lift, short duration,camshaft profiles, were used to initiate HCCIcombustion by increasing the internal exhaust gas recirculation(EGR) and thus retaining sufficient thermalenergy for chemical reactions to occur when a pilot injectionwas introduced prior to TDC, during the NVO.One of the crucial parameters to control in HCCI combustionis the combustion phasing and one way of doingthis is to vary the relative ratio of fuel injected inpilot and main injections. The combustion phasing isalso influenced by the total amount of fuel supplied tothe engine, the combustion phasing is thus affectedwhen the load is changed. This study focuses on thereactions that occur in the highly diluted environmentduring the NVO when load and pilot to main ratio arechanged.To monitor these reactions, planar laser-induced fluorescence(PLIF) from OH radicals was analyzed ina series of experiments with an optical single-cylinderengine, since these radicals are known to be associatedwith high temperature reactions. A series of experimentswas also performed using a multi-cylinderengine with varied NVO timings, which showed thatthe combustion phasing was influenced by both theratio between the pilot and main injection amountsand the total amount of fuel. Data acquired from correspondingoptical analysis showed the occurrenceof OH radicals (and thus high temperature reactions)during the NVO in all tested operating conditions. Theresults also indicate that the extent of the high temperaturereactions was influenced by both varied parameters,since decreasing the relative amount of the pilotinjection and/or increasing the total amount of fuel ledto larger amounts of OH radicals.
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| 47. |
- Berntsson, Andreas, 1978, et al.
(författare)
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LIF imaging of OH during the Negative Valve Overlap of a HCCI Combustion Engine
- 2007
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Ingår i: The Spark Ignition Engine of the Future Conference, Strasbourg - INSA 28/11 - 29/11 2007. ; :Code: R-2007-01-22, s. (9)-
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Konferensbidrag (refereegranskat)abstract
- Future requirements for emission reduction from combustion engines in ground vehicles might be met by using the HCCI combustion concept. In this concept a more or less homogenous air fuel mixture is compressed to auto-ignition. This gives a good fuel economy compared to a normal SI engine and it has a positive impact on exhaust emissions. In the study presented here negative valve overlap (NVO) was used to initiate HCCI combustion by increasing the exhaust gas recirculation (EGR) and thus retaining sufficient thermal energy to reach auto-ignition temperatures, and raising the temperature during the NVO sufficiently to allow reactions to occur when a pilot injection was made prior to the NVO. The focus of the investigation was on the resulting high temperature reactions.Since OH radicals are associated with high temperature reactions, the reactions were followed by monitoring planar laser-induced fluorescence (PLIF) of OH, using a dye laser and an intensified LaVision Dynamight camera. The presence of OH radicals detected during the negative valve overlap indicates that high temperature reactions do occur in the highly diluted environment of the trapped exhaust gases during the NVO. Reactions were identified from 20 CAD prior to TDC (during the NVO) and to around 60 CAD after TDC, with the intensity peak at about TDC.
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| 48. |
- Blomqvist, Göran, 1963-, et al.
(författare)
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Microplastics in snow in urban traffic environments
- 2023
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Microplastics from road traffic, mainly from tyre wear, are globally considered to be one of the largest sources of microplastic contamination in the environment. Plastics can either be deposited in the road vicinity, at the roadside and in ditches or spread via stormwater and air to the environment and receiving water bodies. In cold climates, microplastics, as well as other traffic-related pollutants, can be temporarily stored in snow and ice on and around roads and streets. The location and concentration of these pollutants is influenced by winter operations, where ploughing and skid control contribute to redistribution, and by melting and compaction of ice and snow. This creates reservoirs of microplastics and other pollutants, which are released into stormwater or surrounding soil during thaws, but also provides an opportunity to reduce the spread of microplastics by managing snow and ice appropriately. In the present report, a case study of microplastics in snow has been carried out in the municipality of Karlstad in Sweden, to get an idea of the potential variation, both in terms of concentration and total amounts in relation to traffic and the location of the sampling in the street environment. Microplastics have been analysed by pyrolysis GC/MS to identify tyre-specific polymers in combination with eight commonly occurring plastic types. In addition, six municipalities in different parts of the country responded to a questionnaire on microplastics in snow and urban snowmelt management. The results show that microplastics related to tyre wear (rubber polymers) tend to be present in higher concentrations on and near the carriageway. Other plastics show a less clear link to traffic. Along a salted bicycle lane, an elevated level of polypropylene, from which the brush of the sweep-salting machine is made, could be detected in the surface layer of the snow. In general, knowledge about microplastics in urban snow is low in the municipalities that responded to the survey.
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| 49. |
- Browne, Michael, et al.
(författare)
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MIND THE GAP: THE INTERFACE BETWEEN AUTONOMOUS VEHICLES AND THE LOGISTICS SYSTEM
- 2020
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Purpose Using autonomous vehicles in goods transport has potential benefits. However, the transition to a future autonomous (and electric) freight system needs to take account of the interface between the vehicle and other parts of the logistics system in order to exploit potential benefits and overcome challenges related to the absence of a driver. The purpose of the research is to identify the prerequisites for achieving automated loading, unloading, related information handling and in-plant transport at these interfaces. Research Approach Cases studies consider senders and receivers of various products as well as organisations that have a role including real estate companies that develop warehouses and terminals. The case studies consider vehicle and handling equipment technology alongside the processes that may need to change if the efficiency gains of an autonomous vehicle are to be realised. Research questions are addressed at the logistics system level. The cases studies combine questions about logistics process and technology alongside those concerned with underlying business models. Findings and Originality Results presented are at the half way stage of a two-year project and will be based on the initial series of interviews for four case studies. Findings so far include: (1) lack of development in this topic compared with interest in autonomous and automated transport (2) importance of organisational ssues in the logistics chain e.g. contractual relationships (3) importance of taking a broad view of the companies that need to be involved (4) product type and characteristics are important but other factors may have more influence on the scope to develop initiatives in this area. Research Impact The research provides insights into the complexity of the interfaces in autonomous and automated transport and logistics systems. The empirical findings enrich the discussion of this field. Combining insights from logistics, technology, materials handling and business has demonstrated the benefits of an interdisciplinary approach. Practical Impact Autonomous transport systems may bring many commercial benefits. However, the scale of these benefits will be significantly diminished if questions about the interface points in the logistics system are not addressed. The outputs of the research will provide important insights for managers addressing these challenges.
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| 50. |
- Chorey, Devashish, et al.
(författare)
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Simultaneous imaging of CH*, C*2, and temperature in flames using a DSLR camera and structured illumination
- 2023
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 62:14, s. 3737-3746
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Tidskriftsartikel (refereegranskat)abstract
- Measurement of chemical species and temperature mapping in flames is essential to understanding the combustion process. Multiple cameras are conventionally employed for measurement in such scenarios making the experi-mental setup not only cost-intensive but also challenging. To circumvent this, structured illumination (SI)-based methods are reported for multispecies chemiluminescence (CL) imaging using a single camera. In this paper, we demonstrate four-channel SI-based imaging for simultaneous snapshot CH* and C*2 CL imaging and two-color pyrometry for temperature profiles in a butane diffusion flame. We demonstrate our approach using individual species and multiple species imaging. Taking the advantage of the axisymmetric nature of the flame, the Abel trans-form is performed on the line-of-sight averaged images to obtain deconvoluted images. The deconvoluted maps of temperature are compared with the temperature data obtained by using a physical thermocouple probe. (c) 2023 Optica Publishing Group
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