| 1641. |
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| 1642. |
- Hou, Song, et al.
(författare)
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Oxidation of 4-bromo-4'-chlorobiphenyl, model species for forming mixed halogenated aromatic compounds
- 2017
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Ingår i: International Journal of Environment and Pollution. - : InderScience Publishers. - 0957-4352 .- 1741-5101. ; 61:3-4, s. 243-260
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Tidskriftsartikel (refereegranskat)abstract
- This contribution reports results from the gas-phase oxidation of 4-bromo-4'-chlorobiphenyl (4,4'-BCB) in order to fathom the formation of toxic species produced during the combustion of mixed halogenated aromatics. In their own right, mixed polybrominated/polychlorinated biphenyls (PXBs) represent a new class of environmental contaminants, recently detected in food and human tissues. Gas chromatography-quadrupole mass spectrometry (GC-QMS), gas chromatography-quadrupole time of flight mass spectrometry (GC-QTOFMS), Fourier transform infrared spectroscopy (FTIR) and ion chromatography (IC) served to analyse the volatile and semi-volatile organic compounds (V/SVOCs), including mixed halogenated dibenzo-p-dioxins and dibenzofurans (PXDD/Fs), and gaseous products including HBr/HCl. The selection of non-ortho substituted PXB as a model species yields a large number of halogenated compounds, including monochloro- and monobromobenzene and higher halogenated benzenes and naphthalenes and derivatives of halogenated benzenes (such as 1-chloro-4-ethynylbenzene). We also detect small amounts of chlorinated and mixed halogenated dibenzofurans. The present study provides insights into the formation of several classes of halogenated and mixed-halogenated pollutants in combustion processes involving both bromine and chlorine sources, such as those of brominated flame retardants and PVC plastics.
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| 1643. |
- Husain, Shaheen, et al.
(författare)
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Emerging Trends in Advanced Translational Applications of Silver Nanoparticles : A Progressing Dawn of Nanotechnology
- 2023
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Ingår i: Journal of Functional Biomaterials. - : MDPI. - 2079-4983. ; 14:1
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Forskningsöversikt (refereegranskat)abstract
- Nanoscience has emerged as a fascinating field of science, with its implementation in multiple applications in the form of nanotechnology. Nanotechnology has recently been more impactful in diverse sectors such as the pharmaceutical industry, agriculture sector, and food market. The peculiar properties which make nanoparticles as an asset are their large surface area and their size, which ranges between 1 and 100 nanometers (nm). Various technologies, such as chemical and biological processes, are being used to synthesize nanoparticles. The green chemistry route has become extremely popular due to its use in the synthesis of nanoparticles. Nanomaterials are versatile and impactful in different day to day applications, resulting in their increased utilization and distribution in human cells, tissues, and organs. Owing to the deployment of nanoparticles at a high demand, the need to produce nanoparticles has raised concerns regarding environmentally friendly processes. These processes are meant to produce nanomaterials with improved physiochemical properties that can have significant uses in the fields of medicine, physics, and biochemistry. Among a plethora of nanomaterials, silver nanoparticles have emerged as the most investigated and used nanoparticle. Silver nanoparticles (AgNPs) have become vital entities of study due to their distinctive properties which the scientific society aims to investigate the uses of. The current review addresses the modern expansion of AgNP synthesis, characterization, and mechanism, as well as global applications of AgNPs and their limitations.
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| 1644. |
- Hvitt Strömvall, Ann-Margret, 1963, et al.
(författare)
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Ambient monoterpenes from stone groundwood pulp production
- 1990
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Ingår i: Holzforschung. ; 44, s. 449-452
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Tidskriftsartikel (refereegranskat)abstract
- Composition and ambient concentrations in air were studied for monoterpenes from stone groundwood production at a Swedish plant using exclusively pulp wood from Norway spruce. Field samples were taken on Tenax adsorption cartridges and analyzed by thermal desorption combined with temperature programmed capillary gas chromatography. The major monoterpenes emitted from the process were alpha-pinene(54-59 %) and beta-pinene(24-28 %). Limonene, 3-carene, beta-phellandrene, camphene and myrcene (1-10 % each) followed in decreasing relative proportions. Total ambient monoterpene concentrations above 500 microgram/m3 were assessed at ground level downwind from the emissions. Photo-oxidants formed in the monoterpene plumes are discussed with respect to forest damage and health hazards.
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| 1645. |
- Hvitt Strömvall, Ann-Margret, 1963, et al.
(författare)
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Photooxidant-forming monoterpenes in air plumes from kraft pulp industries
- 1993
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Ingår i: Environmental Pollution. ; 79, s. 219-223
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Tidskriftsartikel (refereegranskat)abstract
- Monoterpenes emitted to air from two Swedish kraft (sulphate) pulp-mills were determined by sampling on the Tenax adsorbent followed by laboratory analysis using thermal desorption combined with high-resolution gas chromatography. The composition of the terpenes was found to be similar in the emissions from various parts of the process as well as in the mill plume. The bicyclic terpenes alpha-pinene and 3-carene, originating principally from wood of Scots pine (Pinus sylvestris), predominated among the thirteen assessed hydrocarbon monoterpenes. Terpinolene was the most prominent among the particularly reactive terpenes with a lifetime in ozone-rich air of only a few minutes. The rapid formation of photooxidants by chemical reactions of the terpenes with other components of the mill plume is discussed. It is concluded that a variety of phytotoxic photooxidants are formed which may contribute significantly to forest decline within 50 km of mills located along coasts.
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| 1646. |
- Hvitt Strömvall, Ann-Margret, 1963, et al.
(författare)
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Protection of terpenes against oxidative and acid decomposition on adsorbent cartridges
- 1992
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Ingår i: Journal of Chromatography. ; 589, s. 385-389
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Tidskriftsartikel (refereegranskat)abstract
- Sampling of monoterpenes from air on Tenax porous polymer may introduce analytical errors owing to oxidation and acid rearrangements on the adsorbent. Particularly terpenes which react rapidly with ozone, e.g. myrcene and limonene, are partially lost when sampling air with high photooxidant levels. On acidified adsoption cartridges, alpha-pinene and beta-pinene may be converted into camphene, limonene, para-cymene and several minor monoterpenes. Pretreatment of the adsorption cartridges with thiosulphate as an antioxidant and hydrogencarbonate as a buffer were found to prevent decomposition and rearrangements. Applications to monoterpenes emitted from the kraft, thermo-mechanical and sulphite pulp industries are presented.
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| 1647. |
- Hvitt Strömvall, Ann-Margret, 1963, et al.
(författare)
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Terpenes emitted to air from TMP and sulphite pulp mills
- 1992
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Ingår i: Holzforschung. ; 46, s. 99-102
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Tidskriftsartikel (refereegranskat)abstract
- Terpenes were studied at two Swedish pulp mills processing wood from Norway spruce (Picea abies). Field samples were adsorbed from air on Tenax cartridges and analyzed in the laboratory by thermal desorption and gas chromatography.The emissions from a large thermomechanical pulp (TMP) plant consisted mainly of chemically unchanged hydrocarbon monoterpenes from the wood. The major monoterpenes were alpha-pinene (>50 %) and beta-pinene (20-30 %).The proportions of ten additional components were determined in the process emissions, which may be recovered to turpentine.The process emissions from a sulphite pulp mill consisted predominantly of the alkylbenzene para-cymene, formed from monoterpenes by acid reactions in the digestors. The contribution of the emissions to photo-oxidant formation in the surrounding region may be significant for both types of mills.
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| 1648. |
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| 1649. |
- Inganäs, Olle, et al.
(författare)
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Alternating Copolymers and Alternative Device Geometries for Organic Photovoltaics
- 2012
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 41:SUPPL.2, s. 138-142
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Tidskriftsartikel (refereegranskat)abstract
- The efficiency of conversion of light to electrical energy with the help of conjugated polymers and molecules is rapidly improving. The optical absorption properties of these materials can be designed, and implemented via molecular engineering. Full coverage of the solar spectrum is thus feasible. Narrow absorption spectra allow construction of tandem solar cells. The poor transport properties of these materials require thin devices, which limits optical absorption. Alternative device geometries for these flexible materials compensate for the optical absorption by light trapping, and allow tandem cells.
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| 1650. |
- Jonsson, Ove, et al.
(författare)
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TIMFIE-provtagning för tidsintegrerad haltbestämning av växtskyddsmedel, PFAS, läkemedel och metaller i ytvatten : En pilotstudie
- 2022
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- TIMFIE (Time Integrating, Micro Flow, In situ Extraction) är en enkel och billig tidsintegrerad provtagningsmetod som här användes för bestämning av ett stort antal organiska ämnen från vitt skilda substansgrupper. Tekniken bygger på kontinuerlig fastfasextraktion i fält under en till två veckor och den efterföljande bestämningen av organiska ämnen är kvantitativ och baseras på helvatten, dvs. med partikelbunden fraktion inkluderad.Förutom organiska ämnen som växtskyddsmedel, PFAS och läkemedel mättes i detta projekt även metallhalter och löst organiskt kol (DOC) i det uppsamlade, filtrerade vattnet. Merparten av de studerade metallerna och DOC påverkades dock negativt av fastfaskolonnerna som används för extraktion av de organiska ämnena. En separat TIMFIE utan kolonner ska därför användas vid bestämning av metaller. En fältstudie med veckovisa TIMFIE-provtagningar i tolv provpunkter fördelade på fem regioner utfördes i samarbete med länsstyrelserna i Gotland, Östergötland och Dalarna samt med en avfallsanläggning i Mälardalen. Totalt analyserades 47 TIMFIE-prover för drygt 200 organiska ämnen och 21 metaller, samt ytterligare 8 TIMFIE-prover endast för metaller.I framtiden kommer två olika TIMFIE-provtagare att användas i studier där både organiska och oorganiska ämnen bestäms. Fortsatt arbete med att även inkludera näringsämnen i det oorganiska analyspaketet pågår och möjligheten att göra dessa bestämningar på ett återskapat helvatten undersöks.
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