| 1. |
- Andersson, Jens A, et al.
(författare)
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Att motivera förändring
- 2004
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Ingår i: 2:a Pedagogiska Inspirationskonferensen 2004. ; , s. 9-11
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Förändringar måste vara väl motiverade och förankrade hos både elever och lärare. De måste vara anpassade till skolans mål och den enskilde studentens behov. I denna rapport presenteras ett antal förslag på lösningar till några av de problem som kan uppstå då man försöker införa nya pedagogiska metoder samt motivationens betydelse för det slutgiltiga resultatet.
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| 2. |
- Fick, Jerker, et al.
(författare)
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A study of the gas-phase ozonolysis of terpenes: the impact of radicals formed during the reaction
- 2002
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Ingår i: Atmospheric Environment. - 1352-2310 .- 1873-2844. ; 36:20, s. 3299-3308
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Tidskriftsartikel (refereegranskat)abstract
- The gas-phase ozonolysis of α-pinene, Δ3-carene and limonene was investigated at ppb levels and the impact of the ozone, relative air humidity (RH), and time was studied using experimental design. The amounts of terpene reacted varied in the different settings and were as high as 8.1% for α-pinene, 10.9% forΔ3-carene and 23.4% for limonene. The designs were able to describe almost all the variation in the experimental data and were also successful in predicting omitted values. The results described the effects of time and ozone and also showed that RH did not have a statistically significant effect on the ozonolysis. The results also showed that all three terpenes were affected by an additional oxidation of OH radicals and/or other reactive species. The results from the designs states that this additional oxidation was responsible for 40% of the total amount of α-pinene reacted, 33% of the total amount of Δ3-carene reacted and 41% of the total amount of limonene reacted at the settings 20 ppb terpene, 75 ppb ozone, 20% RH and a reaction time of 213 s. Additional experiments with 2-butanol as OH radical scavenger showed that the reaction with OH radicals was responsible for 37% of the total α-pinene reacted and 39% of the total Δ3-carene reacted at the same settings. The scavenger experiments also showed that there were no significant amounts of OH radicals formed during the ozonolysis of limonene. The results from the designs were also compared to a mathematical model in order to evaluate further the data.
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| 3. |
- Fick, Jerker, et al.
(författare)
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Effect of OH radicals, relative humidity, and time on the composition of the products formed in the ozonolysis of α-pinene
- 2003
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Ingår i: Atmospheric Environment. ; 37:29, s. 4087-96
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Tidskriftsartikel (refereegranskat)abstract
- The gas-phase ozonolysis of α-pinene at ppb levels were studied and the effects of OH radicals formed in the reaction, the relative humidity (RH), and time on the products formed were investigated. Identified products were pinic acid, glyoxal, methyl glyoxal, norpinonic acid and a norpinonic acid isomer, pinonic acid, a C4 dicarbonyl, a C5 dicarbonyl, norpinon aldehyde, and pinon aldehyde. The different parameters effect on the formation of these products were evaluated using experimental design and multivariate modeling. Pinonic acid, norpinonic acid and its isomer, were not detected in the absence of OH radicals. The amounts of pinic acid, norpinon aldehyde, and pinon aldehyde all decreased in the absence of OH radicals. Glyoxal and methyl glyoxal were not affected.The formation of pinonic acid decreased when the RH was increased. The formation of pinic acid, glyoxal, methyl glyoxal, and pinon aldehyde increased with increasing RH, while norpinon aldehyde was not affected. The implications of these observations and additional interaction effects are discussed, and a novel route of the formation of pinic acid is presented.
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| 4. |
- Fick, Jerker, et al.
(författare)
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Formation of oxidation products in a ventilation system
- 2004
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 38:35, s. 5895-9
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the formation of oxidation products from the ozonolysis of a monoterpene (α-pinene) in an authentic ventilation system. We observed ten products, norpinic acid, pinic acid, glyoxal, methyl glyoxal, norpinonic acid, pinonic acid, a C4 dicarbonyl (C4H6O2), a C5 dicarbonyl (C5H8O2), norpinon aldehyde, and pinon aldehyde. Experiments were conducted at a low (2.0 g m−3) and moderate (8 g m−3) humidity levels. All products but C4 dicarbonyl and norpinon aldehyde were detected at the low humidity level, but only glyoxal, methyl glyoxal, C4 dicarbonyl, norpinon aldehyde and pinon aldehyde were detected at a moderate humidity. Experiments were conducted at low ppb levels (75 ppb ozone and 4 and 10 ppb α-pinene) and with a short reaction time (75 s). Experiments showed that 5–6% of the α-pinene reacted, which was approximately 4–5 times more than predicted by theoretical calculations. This discrepancy suggests a significant contribution from heterogeneous reactions. These oxidation products were formed despite low reactant concentrations and a short reaction time, indicating that the formation of oxidation products likely occurs at ambient levels and in real settings.
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| 5. |
- Fick, Jerker, et al.
(författare)
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Ozone Removal in the Sampling of Parts per Billion Levels of Terpenoid Compounds: An Evaluation of Different Scrubber Materials
- 2001
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Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 35:7, s. 1458-62
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Tidskriftsartikel (refereegranskat)abstract
- Some reactive volatile organic compounds (VOCs) are prone to degradation during sampling in an ozone-rich environment. A wide variety of different chemicals have been used to remove the ozone prior to sampling, but the possibility of interference by such chemicals with the sampled VOCs has not been thoroughly examined. In the present investigation, the retention/degradation of four terpenes (-pinene, -pinene, 3-carene, and limonene) and isoprene together with some of their oxidation products (-pinene oxide, nopinone, 4-acetyl-1-methylcyclohexene (AMCH), methylglyoxal, and methacrolein) has been studied, using various ozone-removing chemicals in an attempt to evaluate their potential as ozone scrubbers in the sampling of ambient air. The chemicals included in this first screening and their ozone-removing capacity are as follows: KI, MnO2, and Na2SO3 removed ozone for more than 24 h when exposed to 73-78 ppb (150-160 g/m3) at a sampling flow rate of 500 mL/min. Silanized poly(1,4-phenylene sulfide) (PFS) removed ozone for 5 h, unsilanized PFS removed ozone for 1 h and 50 min, and Na2S2O3 removed ozone for 20 min. The recovery of the selected compounds with the different scrubbers was >95% for all compounds for KI; >95% for the terpenes oxidation products; >90% for the terpenes and isoprene for PFS; >90% for the terpenes and isoprene for MnO2 on copper nets, Na2SO3, and Na2S2O3; and <90% for the terpenes and isoprene for carulite (a commercial mixture between MnO2, CuO, and Al2O3), CuO, and indigo carmine.
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| 6. |
- Fjällström, Per, et al.
(författare)
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Drying of linseed oil paints : the effects of substrate on the emission of aldehydes
- 2003
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Ingår i: Indoor Air. - : Hindawi Limited. - 0905-6947. ; 13:3, s. 277–82-
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Tidskriftsartikel (refereegranskat)abstract
- The effect of substrate on the emission of aldehydes from linseed oil paint was investigated. Plates of glass, fiberboard, gypsum board, lime mortar and wood lath were painted, and then placed into emission chambers. Samples were collected every eighth hour over 10 days with 2,4-dinitrophenylhydrazin samplers. Analysis was performed with liquid chromatography/UV-detection and mass spectrometry. Paint applied on gypsum board gave the highest total amount of emitted carbonyls, and that on wood lath gave the least. Painted glass had the highest contribution of unsaturated species, and lime mortar, the lowest. Lime mortar also had the highest momentary levels of a single species, 443 nmol/h/m2 of propanal, while fiberboard peaked at only 123 nmol/h/m2 of propanal. In turn, the emission from the painted fiberboard had the slowest decline, and thus at the end of the experiment the highest levels. All substrates gave an emission that peaked within 16 h.
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| 7. |
- Fjällström, Pär, et al.
(författare)
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Drying of linseed oil paints: a laboratory study of aldehyde emissions
- 2002
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Ingår i: Industrial Crops and Products. ; 16:3, s. 173-84
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Tidskriftsartikel (refereegranskat)abstract
- The effects of temperature, air humidity, air exchange rate, artificial light and fatty acid constitution on the emissions of aldehydes from linseed oil paint were investigated. Experiments were designed using a multivariate approach and data were analysed using different projection methods (principal component analysis, partial least-squares). Paints used were produced out of two different types of oils, where the fatty acid chains were either mainly linoleic or linolenic acid. The paints were applied onto glass plates and dried in chambers with a controlled climate. Aldehydes were sampled using silica gel impregnated with 2,4-dinitrophenylhydrazine and analysed by HPLC with UV and MS detection. Consecutive sampling of aldehydes every eighth hour as well as total aldehyde sampling was performed during the first 5 days after application of the paints. Hexanal and propanal were the dominating aldehydes emitted for linoleic and linolenic acid rich paint, respectively. Temperature and humidity sped up the emission process, giving a higher total amount of aldehydes. A higher amount of linoleic acid slowed down the emission process and gave higher total amounts of aldehydes. Artificial light and air exchange rate showed no significant effects on the emission process.
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| 8. |
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| 9. |
- Magnusson, Roger, et al.
(författare)
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Effect of Gasoline and Lubricant on Emissions and Mutagenicity of Particles and Semivolatiles in Chain Saw Exhaust
- 2000
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Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 34:14, s. 2918-24
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Tidskriftsartikel (refereegranskat)abstract
- The exhaust from a two-stroke chain saw engine was characterized using two different types of gasoline, aliphatic gasoline and conventional lead-free gasoline, in combination with four lubricants differing in mineral oil, polyolester, and polyisobutylene (PIB) content. This characterization was focused on emissions of polycyclic aromatic hydrocarbons (PAH) and mutagenicity testing using Ames Salmonella assay. In addition, exhaust emissions of carbon monoxide (CO), nitrogen oxides (NOx), aldehydes, and hydrocarbons (HC) were measured. The two-stroke engine was tested in a test bench, and particulate, semivolatile, and gaseous exhaust components were sampled using a dilution tunnel. Much less PAH were emitted when using aliphatic gasoline due to a much lower gasoline content of PAH and aromatics than the conventional gasoline. Also about half the NOx emissions, up to 50% higher formaldehyde and acetaldehyde emissions, and 10% higher total HC emissions were observed for the aliphatic gasoline. The influence of lubricant on the studied exhaust emissions was found to be of minor importance. In terms of mutagenicity, significant effects were seen for six of the eight gasoline/lubricant combinations, and the highest effects were observed without a metabolizing system. Generally, the conventional gasoline gave higher effects than did the aliphatic gasoline. A difference between lubricants was also seen, especially in combination with gasoline A; however, the interpretation of mutagenic effects of the lubricants was not straightforward. Overall, one synthetic ester-based lubricant and one mineral oil-based lubricant gave the highest mutagenicity.
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| 10. |
- Magnusson, Roger, et al.
(författare)
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Emissions of Aldehydes and Ketones from a Two-Stroke Engine Using Ethanol and Ethanol-Blended Gasoline as Fuel
- 2002
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Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 36:8, s. 1656-64
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Tidskriftsartikel (refereegranskat)abstract
- Besides aliphatic gasoline, ethanol-blended gasoline intended for use in small utility engines was recently introduced on the Swedish market. For small utility engines, little data is available showing the effects of these fuels on exhaust emissions, especially concerning aldehydes and ketones (carbonyls). The objective of the present investigation was to study carbonyl emissions and regulated emissions from a two-stroke chain saw engine using ethanol, gasoline, and ethanol-blended gasoline as fuel (0%, 15%, 50%, 85%, and 100% ethanol). The effects of the ethanol-blending level and mechanical changes of the relative air/fuel ratio, , on exhaust emissions was investigated, both for aliphatic and regular gasoline. Formaldehyde, acetaldehyde, and aromatic aldehydes were the most abundant carbonyls in the exhaust. Acetaldehyde dominated for all ethanol-blended fuels (1.2-12 g/kWh, depending on the fuel and ), and formaldehyde dominated for gasoline (0.74-2.3 g/kWh, depending on the type of gasoline and ). The main effects of ethanol blending were increased acetaldehyde emissions (30-44 times for pure ethanol), reduced emissions of all other carbonyls except formaldehyde and acrolein (which showed a more complex relation to the ethanol content), reduced carbon monoxide (CO) and ntirogen oxide (NO) emissions, and increased hydrocarbon (HC) and nitrogen dixodie (NO2) emissions. The main effects of increasing were increased emissions of carbonyls and nitrogen oxides (NOx) and reduced CO and HC emissions. When the two types of gasoline are considered, benzaldehyde and tolualdehyde could be directly related to the gasoline content of aromatics or olefins, but also acrolein, propanal, crotonaldehyde, and methyl ethyl ketone mainly originated from aromatics or olefins, while the main source for formaldehyde, acetaldehyde, acetone, methacrolein, and butanal was saturated aliphatic hydrocarbons.
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