| 51881. |
- Mattsson, U, et al.
(författare)
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Nickel affects activity more than expression of hydrogenase protein in Frankia
- 2002
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Ingår i: Current Microbiology. - 0343-8651 .- 1432-0991. ; 44:2, s. 88-93
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Tidskriftsartikel (refereegranskat)abstract
- The effects of nickel on hydrogen uptake and the post-translational processing of the large subunit of the hydrogenase protein in three Frankia strains (one isolated from an Alnus-Frankia symbiosis and two from Casuarina-Frankia associations) were investigated. All three strains responded to the addition of nickel with an increase in hydrogen uptake. Additional nickel did not affect nitrogenase activity, however evolved hydrogen was detected in Frankia KB5 in the absence of additional nickel, indicating that hydrogenase was not active. No increase in the processing rate of the hydrogenase large subunit was found with increasing nickel concentrations for any of the strains, indicating that the strategy for regulating hydrogenase in Frankia is different from that in other microorganisms.
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| 51882. |
- Mattsson, Åse, et al.
(författare)
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Exposure of HepG2 cells to low levels of PAH-containing extracts from contaminated soils results in unpredictable genotoxic stress responses
- 2009
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Ingår i: Environmental and Molecular Mutagenesis. - : John Wiley & Sons. - 0893-6692 .- 1098-2280. ; 50:4, s. 337-348
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Tidskriftsartikel (refereegranskat)abstract
- Contaminated soil is a serious environmental problem, constituting a risk to humans and the environment. Polycyclic aromatic hydrocarbons (PAHs) are often present at contaminated sites. However, risk levels are difficult to estimate because of the complexity of contaminants present. Here, we compare cellular effects of extracts from contaminated soils collected at six industrial settings in Sweden. Chemical analysis showed that all soils contained complex mixtures of PAHs and oxy-PAHs. Western blotting and immunocytochemistry were used to investigate DNA damage signaling in HepG2 cells exposed to extracts from these soils. The effects on phosphorylated Mdm2, p53, Erk, H2AX, 53BP1, and Chk2, cell cycle regulating proteins (cyclin D1 and p21), and cell proliferation were compared. We found that most soil extracts induced phosphorylation of Mdm2 at the 2A10 epitope at low concentrations. This is in line with previous studies suggesting that this endpoint reflects readily repaired DNA-damage. However, we found concentration and time-dependent gamma H2AX and 53BP1 responses that were sustained for 48 hr. These endpoints may reflect the presence of different types of persistent DNA-damage. High concentrations of soil extracts decreased cyclin D1 and increased p21 response, indicating cell cycle arrest. Phosphorylation of Mdm2 at Ser 166, which attenuates the p53 response and is induced by many tumor promoters, was induced in a time-dependent manner and was associated with Erk phosphorylation. Taken together, the PAH extracts elicited unpredictable signaling responses that differed between samples. More polar compounds, i.e., oxy-PAHs, also contributed to the complexity.
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| 51883. |
- Matuseviciene, Giedre, et al.
(författare)
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Early intervention for patients at risk for persisting disability after mild traumatic brain injury : A randomized, controlled study
- 2013
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Ingår i: Brain Injury. - : Informa UK Limited. - 0269-9052 .- 1362-301X. ; 27:3, s. 318-324
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Tidskriftsartikel (refereegranskat)abstract
- Study objective: To investigate the effect of an early intervention visit in addition to written information and treatment as usual for patients with an estimated high risk for persisting disability after a mild traumatic brain injury (MTBI). Research design: Randomized controlled trial. Methods: One hundred and seventy-three patients, aged 15-70 years with a Glasgow Coma Scale of 14-15 were included. All received written information about MTBI. Ninety-seven patients who reported three or more symptoms according to the Rivermead Post-Concussion Symptoms Questionnaire (RPQ) at 10 days after the injury were considered as high-risk patients and were randomized to either early visit to a doctor or to treatment as usual (TAU); all patients including the 76 low-risk patients were followed-up at 3 months. Completion rate was 83%. Outcome measures included RPQ and the Hospital Anxiety and Depression Scale. Results: RPQ symptoms decreased significantly in both randomized groups, but were not significantly different in the groups at 3 months. At 3 months, anxiety and depression scores did not differ between groups. Conclusions: An early intervention, offered to patients with an estimated high risk for persisting disability, had no additional effect on symptom level at 3 months after MTBI as compared to TAU.
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| 51884. |
- Matyba, Piotr, et al.
(författare)
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Flexible and Metal-Free Light-Emitting Electrochemical Cells Based on Graphene and PEDOT-PSS as the Electrode Materials
- 2010
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Ingår i: ACS NANO. - Washington D.C. : American Chemical Society. - 1936-0851 .- 1936-086X. ; 5:1, s. 574-580
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Tidskriftsartikel (refereegranskat)abstract
- We report flexible and metal free light-emitting electrochemical cells (LECs) using exclusively solution processed organic materials and illustrate interesting design opportunities offered by such conformable devices with transparent electrodes. Flexible LEC devices based on chemically derived graphene (COG) as the., cathode and poly(3,4-ethylenedioxythiophene) mixed with poly(styrenesulfonate) as the anode exhibit a low turnon voltage for yellow light emission (V = 2.8 V) and a good efficiency 2.4 (4.0) cd/A at a brightness of 100 (50) cd/m(2). We also find that COG is electrochemically inert over a wide potential range (+1.2 to -2.8 V vs ferrocene/ferrocenium) and exploit this property to demonstrate planar LEC devices with COG as both the anode and the cathode.
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| 51885. |
- Matyba, Piotr, 1982-, et al.
(författare)
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Graphene and Mobile Ions: The Key to All-Plastic, Solution-Processed Light-Emitting Devices
- 2010
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Ingår i: ACS NANO. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 4:2, s. 637-642
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Tidskriftsartikel (refereegranskat)abstract
- The emerging field of "organic" or "plastic" electronics has brought low-voltage, ultrathin, and energy-efficient lighting and displays to market as organic light-emitting diode (OLED) televisions and displays in cameras and mobile phones. Despite using carbon-based materials as the light-emitting layer, previous efficient organic electronic light-emitting devices have required at least one metal electrode. Here, we utilize chemically derived graphene for the transparent cathode in an all-plastic sandwich-structure device, similar to an OLED, called a light-emitting electrochemical cell (LEC). Using a screen-printable conducting polymer as a partially transparent anode and a micro meter-thick active layer solution-deposited from a blend of a light-emitting polymer and a polymer electrolyte, we demonstrate a light-emitting device based solely on solution-processable carbon-based materials. Our results demonstrate that low-voltage, inexpensive, and efficient light-emitting devices can be made without using metals. In other words, electronics can truly be "organic".
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| 51886. |
- Matyba, Piotr, 1982-, et al.
(författare)
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On the desired properties of a conjugated polymer-electrolyte blend in a light-emitting electrochemical cell
- 2008
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Ingår i: Organic Electronics: physics, materials, applications. - : Elsevier BV. - 1566-1199 .- 1878-5530. ; 9:5, s. 699-710
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Tidskriftsartikel (refereegranskat)abstract
- We present results from a systematic study on the influence of the conjugated polymer (CP) on the performance of planar light-emitting electrochemical cells (LECs) with a device structure of Au/{CP + poly(ethylene oxide) (PEO) + KCF 3 SO 3 }/Au. We have employed six different CPs, and we demonstrate that in order to attain a fast turn-on time and a strong light emission intensity, it is critical that the p-type doping (oxidation) potential of the CP is situated within the electrochemical stability window of the {PEO + KCF 3 SO 3 } electrolyte. We also find that a high ionic conductivity of the active material correlates with a small phase separation between the CP and the {PEO + KCF 3 SO 3 } electrolyte, and that a doping concentration of ∼0.1 dopants/CP repeat unit is a generic feature of the progressing doping fronts in all investigated devices. Finally we report the first observation of a light emission zone positioned in close proximity to the positive anode in a CP-based LEC. © 2008 Elsevier B.V. All rights reserved.
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| 51887. |
- Matyba, Piotr, 1982-
(författare)
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Polymer light-emitting electrochemical cells : Utilizing doping for generation of light
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The current implementation of conjugated polymers (“conducting plastics”) in a wide range of devices promises to bring the vision of a new generation of flexible, efficient and low-cost applications to reality. Plastic lightemitting devices in the form of polymer light-emitting diodes (PLEDs) are projected to be particularly close to the market in applications such as large area and conformable illumination panels and high-performance thin displays. However, two notable drawbacks of PLEDs are that they depend on vacuum deposition of a reactive metal for the negative electrode and that the active material must be extremely thin and uniform in thickness. As a consequence, PLEDs cannot be expected to allow for a low-cost continuous production using a roll-to-roll coating and/or printing process. This thesis focuses on an alternative to the PLED: A light-emitting electrochemical cell (LEC). LECs comprise a mixture of a conjugated polymer and a solid-state electrolyte as the active material positioned between two electrodes. The existence of mobile ions in the active material allows for a number of interesting attributes, both from a fundamental science and an application perspective. Importantly, the ions and the related unique operation of LECs make these devices apt for the utilization of low-cost roll-to-roll fabrication of the entire device as the electrode materials can be air stable and solution-processible and the requirement on the thickness of the active material is much less stringent than in PLEDs. The herein presented “basic science” studies primarily focus on the operation of LECs. It is for instance firmly established that a light-emitting p-n junction can form in-situ in a LEC device during the application of a voltage. This dynamic p-n junction exhibits some similarities, but also distinct differences, in comparison to the static p-n junctions that are exploited in crystalline inorganic semiconductor devices. We have also systematically explored the role that the constituent materials (ions, conjugated polymer, ionic solvent, and electrode material) can have on the performance of LECs, and two of the more important findings are that the concentration of ions can influence the doping structure in a motivated fashion and that it is critically important to consider the electrochemical stability window of the constituent materials in order to attain stable device operation. With this knowledge at hand, we have executed a number of more “applied science” studies, where we have used the acquired information from the basic-science studies for the rational design of improved devices. We have demonstrated LEC devices with significantly improved device performance, as exemplified by an orange-red device that emitted significant light (> 100 cd/m2) for more than one month of uninterrupted operation, and a yellow-green device that emitted significant light for 25 days at a low voltage of 4 V and at relatively high efficiency (6 lm/W). Finally, we have conceptualized and realized a solely solution-processed and metal-free LEC comprising graphene as the negative electrode and the conducting polymer PEDOT-PSS as the positive electrode. This type of devices represents a paradigm shift in the field of solid-state lighting as they demonstrate that it is possible to fabricate an entire light-emitting device from solution-processible and “green” carbon-based materials in a process that is akin to printing.
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| 51888. |
- Matyba, Piotr, 1982-, et al.
(författare)
-
The dynamic organic p-n junction
- 2009
-
Ingår i: Nature Materials. - London, UK : Nature Publishing Group. - 1476-1122 .- 1476-4660. ; 8:8, s. 672-676
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Tidskriftsartikel (refereegranskat)abstract
- Static p-n junctions in inorganic semiconductors are exploited in a wide range of todays electronic appliances. Here, we demonstrate the in situ formation of a dynamic p-n junction structure within an organic semiconductor through electrochemistry. Specifically, we use scanning kelvin probe microscopy and optical probing on planar light-emitting electrochemical cells (LECs) with a mixture of a conjugated polymer and an electrolyte connecting two electrodes separated by 120 mu m. We find that a significant portion of the potential drop between the electrodes coincides with the location of a thin and distinct light-emission zone positioned andgt;30 mu m away from the negative electrode. These results are relevant in the context of a long-standing scientific debate, as they prove that electrochemical doping can take place in LECs. Moreover, a study on the doping formation and dissipation kinetics provides interesting detail regarding the electronic structure and stability of the dynamic organic p-n junction, which may be useful in future dynamic p-n junction-based devices.
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| 51889. |
- Matyszewska, Dorota, et al.
(författare)
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Influence of Perfluorinated Compounds on the Properties of Model Lipid Membranes
- 2007
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Ingår i: J. Phys. Chem. B. - : American Chemical Society (ACS). ; 111, s. 9908-18
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Tidskriftsartikel (refereegranskat)abstract
- The influence of selected perfluorinated compounds (PFCs), perfluorooctanoic acid (PFOA) or perfluorooctanesulfonic acid (PFOS), on the structure and organization of lipid membranes was investigated using model membranes-lipid monolayers and bilayers. The simplest model-a lipid monolayer-was studied at the air-water interface using the Langmuir-Blodgett technique with surface pressure and surface potential measurements. Lipid bilayers were characterized by NMR techniques and molecular dynamics simulations. Two phospholipids, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), characterized by different surface properties have been chosen as components of the model membranes. For a DPPC monolayer, a phase transition from the liquid-expanded state to the liquid-condensed state can be observed upon compression at room temperature, while a DMPC monolayer under the same conditions remains in the liquid-expanded state. For each of the two lipids, the presence of both PFOA and PFOS leads to the formation of a more fluidic layer at the air-water interface. Pulsed field gradient NMR measurements of the lateral diffusion coefficient (DL) of DMPC and PFOA in oriented bilayers reveal that, upon addition of PFOA to DMPC bilayers, DL of DMPC decreases for small amounts of PFOA, while larger additions produce an increased DL. The DL values of PFOA were found to be slightly larger than those for DMPC, probably as a consequence of the water solubility of PFOA. Furthermore, 31P and 2H NMR showed that the gel-liquid crystalline phase transition temperature decreased by the addition of PFOA for concentrations of 5 mol % and above, indicating a destabilizing effect of PFOA on the membranes. Deuterium order parameters of deuterated DMPC were found to increase slightly upon increasing the PFOA concentration. The monolayer experiments reveal that PFOS also penetrates slowly into already preformed lipid layers, leading to a change of their properties with time. These experimental observations are in qualitative agreement with the computational results obtained from the molecular dynamics simulations showing a slow migration of PFCs from the surrounding water phase into DPPC and DMPC bilayers.
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| 51890. |
- Mau, Steffen, 1968-, et al.
(författare)
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Horizontal europeanisation in contextual perspective : what drives cross-border activities within the European Union?
- 2012
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Ingår i: European Societies. - : Routledge. - 1461-6696 .- 1469-8307. ; 14:1, s. 7-34
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Tidskriftsartikel (refereegranskat)abstract
- In the current discourse it is frequently stated that in the course of European integration and globalisation we witness more intensified and more frequent transactions spanning across national borders. These assumptions relate not only to transactions in the economic sphere or to forms of political co-operation, but to the individual lifeworlds as well. Yet concerning the latter dimension, research into the patterns and dynamics of interpersonal interaction, relationships, and forms of mobility across national borders is scarce. This paper is a contribution towards filling this research lacuna. It addresses the question of the extent to which horizontal Europeanisation, understood as different forms of individual cross-border activities within the European Union, depends on characteristics at the country level. From a comparative perspective we will analyse the transnational mobility and cross-border networks of European citizens within a European context. Empirically, we refer to data from the Eurobarometer 65.1 (2006), which allows us to answer the question how certain contextual variables, such as internationalisation, modernisation, and characteristics such as the respective country's geography, affect people's participation in cross-border activities. Based on a sample of 25 European countries, we will demonstrate that geographic characteristics drive social transnationalism less than internationalisation, Europeanisation, and modernisation, which contribute to a proliferation of individual transnational activities across the European Union.
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