Secondary Organic Aerosol Formation from Healthy and Aphid-Stressed Scots Pine Emissions.

One barrier to predicting biogenic secondary organic aerosol (SOA) formation in a changing climate can be attributed to the complex nature of plant volatile emissions. Plant volatile emissions are dynamic over space and time, and change in response to environmental stressors. This study investigated SOA production from emissions of healthy and aphid-stressed Scots pine saplings via dark ozonolysis and photooxidation chemistry. Laboratory experiments using a batch reaction chamber were used to investigate SOA production from different plant volatile mixtures. The volatile mixture from healthy plants included monoterpenes, aromatics, and a small amount of sesquiterpenes. The biggest change in the volatile mixture for aphid-stressed plants was a large increase (from 1.4 to 7.9 ppb) in sesquiterpenes-particularly acyclic sesquiterpenes, such as the farnesene isomers. Acyclic sesquiterpenes had different effects on SOA production depending on the chemical mechanism. Farnesenes suppressed SOA formation from ozonolysis with a 9.7-14.6% SOA mass yield from healthy plant emissions and a 6.9-10.4% SOA mass yield from aphid-stressed plant emissions. Ozonolysis of volatile mixtures containing more farnesenes promoted fragmentation reactions, which produced higher volatility oxidation products. In contrast, plant volatile mixtures containing more farnesenes did not appreciably change SOA production from photooxidation. SOA mass yields ranged from 10.8 to 23.2% from healthy plant emissions and 17.8-26.8% for aphid-stressed plant emissions. This study highlights the potential importance of acyclic terpene chemistry in a future climate regime with an increased presence of plant stress volatiles

Factors controlling the evaporation of secondary organic aerosol from alpha-pinene ozonolysis

Secondary organic aerosols (SOA) forms a major fraction of organic aerosols in the atmosphere. Knowledge of SOA properties that affect their dynamics in the atmosphere is needed for improving climate models. By combining experimental and modeling techniques, we investigated the factors controlling SOA evaporation under different humidity conditions. Our experiments support the conclusion of particle phase diffusivity limiting the evaporation under dry conditions. Viscosity of particles at dry conditions was estimated to increase several orders of magnitude during evaporation, up to 10(9)Pas. However, at atmospherically relevant relative humidity and time scales, our results show that diffusion limitations may have a minor effect on evaporation of the studied -pinene SOA particles. Based on previous studies and our model simulations, we suggest that, in warm environments dominated by biogenic emissions, the major uncertainty in models describing the SOA particle evaporation is related to the volatility of SOA constituents.Peer reviewe

Composition and volatility of secondary organic aerosol (SOA) formed from oxidation of real tree emissions compared to simplified volatile organic compound (VOC) systems

Secondary organic aerosol (SOA) is an important constituent of the atmosphere where SOA particles are formed chiefly by the condensation or reactive uptake of oxidation products of volatile organic compounds (VOCs). The mass yield in SOA particle formation, as well as the chemical composition and volatility of the particles, is determined by the identity of the VOC precursor(s) and the oxidation conditions they experience. In this study, we used an oxidation flow reactor to generate biogenic SOA from the oxidation of Scots pine emissions. Mass yields, chemical composition and volatility of the SOA particles were characterized and compared with SOA particles formed from oxidation of α-pinene and from a mixture of acyclic–monocyclic sesquiterpenes (farnesenes and bisabolenes), which are significant components of the Scots pine emissions. SOA mass yields for Scots pine emissions dominated by farnesenes were lower than for α-pinene but higher than for the artificial mixture of farnesenes and bisabolenes. The reduction in the SOA yield in the farnesene- and bisabolene-dominated mixtures is due to exocyclic C=C bond scission in these acyclic–monocyclic sesquiterpenes during ozonolysis leading to smaller and generally more volatile products. SOA particles from the oxidation of Scots pine emissions had similar or lower volatility than SOA particles formed from either a single precursor or a simple mixture of VOCs. Applying physical stress to the Scots pine plants increased their monoterpene, especially monocyclic β-phellandrene, emissions, which further decreased SOA particle volatility and increased SOA mass yield. Our results highlight the need to account for the chemical complexity and structure of real-world biogenic VOC emissions and stress-induced changes to plant emissions when modelling SOA production and properties in the atmosphere. These results emphasize that a simple increase or decrease in relative monoterpene and sesquiterpene emissions should not be used as an indicator of SOA particle volatility

Localized delivery of compounds into articular cartilage by using high-intensity focused ultrasound

Localized delivery of drugs into an osteoarthritic cartilaginous lesion does not yet exist, which limits pharmaceutical management of osteoarthritis (OA). High-intensity focused ultrasound (HIFU) provides a means to actuate matter from a distance in a non-destructive way. In this study, we aimed to deliver methylene blue locally into bovine articular cartilage in vitro. HIFU-treated samples (n = 10) were immersed in a methylene blue (MB) solution during sonication (f = 2.16 MHz, peak-positivepressure = 3.5 MPa, mechanical index = 1.8, pulse repetition frequency = 3.0 kHz, cycles per burst: 50, duty cycle: 7%). Adjacent control 1 tissue (n = 10) was first pre-treated with HIFU followed by immersion into MB; adjacent control 2 tissue (n = 10) was immersed in MB without ultrasound exposure. The MB content was higher (p 0.05). To conclude, HIFU delivers molecules into articular cartilage without major short-term concerns about safety. The method is a candidate for a future approach for managing OA.Peer reviewe

Potential of partial-filling affinity capillary electrophoretic methods in biological studies

Biological interactions have been studied by many different techniques. One of the frequently applied techniques is affinity capillary electrophoresis (ACE), which has proven to be effective, fast and simple, especially for the elucidation of molecular non-covalent interactions and for the determination of binding constants between receptors and ligands. However, traditional ACE has disadvantages, when highly UV absorbing compounds, such as proteins are studied and when a limited amount of sample is available. Fortunately, these disadvantages can be overcome by partial-filling affinity capillary electrophoresis (PFACE), which was developed to minimize the consumption of sample. Different PFACE methods have been successfully utilized for the interaction studies between different biological compounds including proteins, ligands, D-alanine-D-alanine terminus peptides and glycopeptide antibiotics. Literature part of this M.Sc. thesis concentrates on different PFACE methods and on their utilization for the clarification of different biological interactions. In the experimental part the applicability of two different capillary electrophoretic systems, capillary electrochromatography and PFACE, to the studies on high-density lipoprotein (HDL), apolipoprotein (apo) A-I, phospholipid transfer protein (PLTP) and cholesteryl ester transfer protein (CETP) was clarified. Because all of these biomolecules have links to the development of atherosclerosis by removing cholesterol from peripheral cells, their investigation is an important topic. Both capillary electromigration techniques demonstrated that not only apoA-I of HDL, but also lipids play a role in the interactions with PLTP and CETP.Biologisia vuorovaikutuksia tutkitaan hyvin erilaisin tekniikoin, joista yksi yleisesti käytetty on affiniteetti kapillaarielektroforeesi (ACE). ACE on osoittautunut tehokkaaksi, nopeaksi sekä yksinkertaiseksi erityisesti molekyylien välisten, ei kovalenttisten vuorovaikutusten tutkimuksissa ja sitoutumisvakioiden määrityksissä reseptori-ligandi vuorovaikutuksille. Perinteisellä affiniteettikapillaarielektroforeesilla on kuitenkin valitettavasti myös heikkouksia, nimenomaan kun tutkitaan UV-alueella voimakkaasti absorboivia yhdisteitä, kuten proteiineja,tai kun näytettä on saatavilla vain rajoitettu määrä. Nämä ongelmat voidaan ratkaista affiniteettikapillaarielektroforeesi menetelmällä, kun käytetään osittaistäyttösysteemiä (PFACE). Ko. tekniikka on kehitetty erityisesti minimoimaan näytteenkulutusta. PFACE –menetelmiä on onnistuneesti käytetty erilaisten biologisten yhdisteiden vuorovaikutustutkimuksissa, joista mainittakoon proteiinit, ligandit, D-alaniini-D-alaniini ketjuun päättyvät peptidit ja glykopeptidiantibiootit. Tämän pro-gradu tutkielman kirjallisessa osassa keskitytään PFACE-menetelmiin ja niiden hyödyntämiseen biologisissa vuorovaikutustutkimuksissa. Tutkielman kokeellisessa osiossa tutkitaan kahden erilaisen kapillaarielektroforeettisen menetelmän, kapillaarielektrokromatografian ja PFACE:n soveltuvuutta HDL:n, apolipoproteiini (apo) A-I:n, fosfolipidin siirtäjäproteiinin (PLTP) ja kolesteroliesterisiirtäjäproteiinin (CETP) tutkimuksiin. Näillä kaikilla biomolekyyleillä on yhteys ateroskleroosin kehittymiseen, sillä ne poistavat kolesterolia perifeerisistä soluista. Molemmat tutkimuksissa käytetyt kapillaarielektromigraatiotekniikat osoittivat, ettei HDL:ssa oleva apo A-I vuorovaikuta ainoastaan PLTP:n ja CETP:n kanssa, vaan HDL:n lipideillä on myös oma roolinsa näissä vuorovaikutuksissa

Effect of Decreased Temperature on the Evaporation of α-Pinene Secondary Organic Aerosol Particles

The interplay of volatility distribution and particle viscosity governs the gas-to-particle partitioning dynamics of atmospheric secondary organic aerosol (SOA) constituents. Temperature-induced shifts in both particle volatility distribution and viscosity can influence the evaporation behavior of atmospheric SOA particles. However, knowledge of particle evaporation at low temperatures is still limited. Here, we combined isothermal evaporation measurements and process modeling to explore the evaporation of α-pinene ozonolysis (αpinO3) and photo-oxidation (αpinOH) SOA particles under a series of relative humidities (RHs) at two different temperatures. Experimental results revealed that the particle evaporation was hindered at low temperature in agreement with the temperature dependence of the effective saturation vapor concentration and the possible temperature impact on the particle viscosity. Both αpinO3 and αpinOH SOA particles showed similar evaporation rates at 80% RH when particles were in a liquid state. However, they showed different evaporation behaviors when present in a semi-solid phase state at low RH. Furthermore, using the evaporation measurement data in model simulations, we could derive particle volatility distributions, enthalpies of vaporization, and composition-dependent viscosities for both the investigated SOA systems. The observed particle size change was well reproduced by process models using the fitted particle volatility distribution and viscosity. Although the observed evaporation rate of α-pinene SOA particles at an intermediate RH is similar to high RH (80% RH), the simulation results showed that the evaporation of organic compounds from viscous particles shifts from a liquid-like process at the initial stage to a kinetic-limited one at the later stage of evaporation.</p