| 1. |
- Mathijssen, Simon G. J., et al.
(author)
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Manipulating the local light emission in organic light-emitting diodes by using patterned self-assembled monolayers
- 2008
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In: Advanced Materials. - : Wiley-VCH Verlag. - 0935-9648 .- 1521-4095. ; 20:14, s. 2703-
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Journal article (peer-reviewed)abstract
- Patterned organic light-emitting diodes are fabricated by using microcontactDrinted self-assembled monolayers on a gold anode (see background figure). Molecules with dipole moments in opposite directions result in an increase or a decrease of the local work function (foreground picture), providing a direct handle on charge injection and enabling local modification of the light emission
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| 2. |
- Smits, Edsger C. P., et al.
(author)
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Bottom-up organic integrated circuits
- 2008
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In: Nature. - : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 455:7215, s. 956-959
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Journal article (peer-reviewed)abstract
- Self- assembly - the autonomous organization of components into patterns and structures(1) - is a promising technology for the mass production of organic electronics. Making integrated circuits using a bottom- up approach involving self- assembling molecules was proposed(2) in the 1970s. The basic building block of such an integrated circuit is the self- assembled- monolayer field- effect transistor ( SAMFET), where the semiconductor is a monolayer spontaneously formed on the gate dielectric. In the SAMFETs fabricated so far, current modulation has only been observed in submicrometre channels(3-5), the lack of efficient charge transport in longer channels being due to defects and the limited intermolecular pi-pi coupling between the molecules in the self-assembled monolayers. Low field- effect carrier mobility, low yield and poor reproducibility have prohibited the realization of bottom- up integrated circuits. Here we demonstrate SAMFETs with long- range intermolecular pi - pi coupling in the monolayer. We achieve dense packing by using liquid- crystalline molecules consisting of a pi- conjugated mesogenic core separated by a long aliphatic chain from a monofunctionalized anchor group. The resulting SAMFETs exhibit a bulk- like carrier mobility, large current modulation and high reproducibility. As a first step towards functional circuits, we combine the SAMFETs into logic gates as inverters; the small parameter spread then allows us to combine the inverters into ring oscillators. We demonstrate real logic functionality by constructing a 15- bit code generator in which hundreds of SAMFETs are addressed simultaneously. Bridging the gap between discrete monolayer transistors and functional self-assembled integrated circuits puts bottom- up electronics in a new perspective.
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| 3. |
- Abalos, M., et al.
(author)
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Results for PCDD/PCDF and dl-PCBs in the first round of UNEPs biennial global interlaboratory assessment on persistent organic pollutants
- 2013
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In: TrAC. Trends in analytical chemistry. - : Elsevier BV. - 0165-9936 .- 1879-3142. ; 46, s. 98-109
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Journal article (peer-reviewed)abstract
- The first worldwide interlaboratory assesment on persistent organic pollutants (POPs) under the Stockholm Convention was organized in the Asian/Pacific, Latin American and African regions during 2009-11.A relatively large number of laboratories reported data for the PCDDs/PCDFs and dioxin-like PCBs, especially in the Asian region. Within the Asian region, several participants used high-resolution GC/high-resolution MS systems optimized for dioxin analysis. The availibility of High-resolution mass spectrometer instrumentation is limited in the Latin America and African regions, although recently several new laboratories for dioxins have started in the Latin American region.
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| 4. |
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| 5. |
- de Boer, J., et al.
(author)
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United Nations Environment Programme Capacity Building Pilot Project : training and interlaboratory study on persistent organic pollutant analysis under the Stockholm Convention
- 2008
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In: Analytica Chimica Acta. - : Elsevier BV. - 0003-2670 .- 1873-4324. ; 617:1-2, s. 208-215
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Journal article (peer-reviewed)abstract
- Within the framework of a United Nations Environment Programme (UNEP) Capacity Building Project for training of laboratory staff in developing countries on persistent organic pollutant (POP) analysis, an interlaboratory study was organised following an initial evaluation of the performance of laboratories (reality check) and a series of training sessions. The target compounds were polychlorinated biphenyls (PCB) and organochlorine pesticides (OCP). Seven laboratories from five countries (Ecuador, Uruguay, Kenya, Moldova, and Fiji) participated. Most of the laboratories had no experience in determining PCBs. Although chromatograms improved considerably after the training and installation of new gas chromatographic (GC) columns at participating laboratories, the level of performance in the interlaboratory study was essentially on par with the moderate performance level achieved by European POP laboratories in the 1980s. Only some individual results were within +/-20% of the target values. The relative standard deviations (R.S.D.s) in POP concentrations determined by laboratories in a sediment sample were >200% in a number of cases. The results for a certified herring sample were better with at least some R.S.D. values below 50% and most below 100%. Clean up was as one of the main sources of error. After inspection it was ascertained that training of laboratory staff and investments in simple consumables such as glassware and GC columns would help to improve the quality of the analysis more than major investments in expensive instrumentation. Creating an effective network of POP laboratories at different continents together with a series of interlaboratory studies and workshops is suggested to improve the measurements of POPs in these countries.
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| 6. |
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| 7. |
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| 8. |
- Fiedler, Heidelore, 1953-, et al.
(author)
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The need for capacity building and first results for the Stockholm convention global monitoring plan
- 2013
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In: TrAC. Trends in analytical chemistry. - : Elsevier BV. - 0165-9936 .- 1879-3142. ; 46, s. 72-84
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Journal article (peer-reviewed)abstract
- The Stockholm Convention on Persistent Organic Pollutants (POPs) established an effectiveness evaluation to assess the efficiency of measures taken by Parties under the Convention. Among these measures, a Global Monitoring Plan requires countries to analyze core matrices for POPs. To assist countries in setting up networks for these core matrices and to generate high-quality, comparable results, the United Nations Environment Program has implemented projects in 32 developing countries. The results demonstrate the worldwide presence of POPs in air and in humans, although at different scales.
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| 9. |
- Lal, Vincent, et al.
(author)
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Capacity building for persistent organic pollutant (POP) analysis in the Pacific and POP trends in the Pacific Islands
- 2013
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In: TrAC. Trends in analytical chemistry. - : Elsevier BV. - 0165-9936 .- 1879-3142. ; 46, s. 173-177
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Journal article (peer-reviewed)abstract
- This article gives an overview of activities relating to the establishment of a regional center of excellence for testing persistent organic pollutants (POPs) in the Pacific Island Region. It highlights the areas of analytical procedures that needed improvement to perform trace-level POP testing in human-breast milk. It describes the actions taken by the POP expert group of the United Nations Environment Programme (UNEP) Chemicals during inspection visits and in setting up analytical procedures and proficiency tests to achieve acceptable levels of results for testing POPs regionally. It also describes results of early studies on POPs in human-breast milk in several Pacific Island countries, which generally show relatively low levels.
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| 10. |
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| 11. |
- Leslie, H. A., et al.
(author)
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Towards comparable POPs data worldwide with global monitoring data and analytical capacity building in Africa, Central and Latin America, and the South Pacific
- 2013
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In: TrAC. Trends in analytical chemistry. - : Elsevier BV. - 0165-9936 .- 1879-3142. ; 46, s. 85-97
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Journal article (peer-reviewed)abstract
- The United Nations Environment Program (UNEP)/Global Environment Facility (GEF) created a capacity-building initiative to support the Global Monitoring Plan (GMP) for persistent organic pollutants (POPs), in which the collection of high-quality, comparable, POPs-monitoring data from all regions is critical for the identification of time trends and regional and global environmental transport. In a series of projects involving countries in West and East Africa, the Caribbean, Latin America and the South Pacific, the study design consisted of a combination of theoretical and hands-on training provided by a pool of three expert laboratories appointed by UNEP combined with POPs analysis in all areas by expert laboratories.
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| 12. |
- Rotander, Anna, 1978-
(author)
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Monitoring persistent organic pollutants (POPs) in sub-Arctic and Arctic marine mammals, 1984 - 2009
- 2011
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Doctoral thesis (other academic/artistic)abstract
- The Arctic has become an important indicator region for assessing persistence and bioaccumulation properties of persistent organic pollutants (POPs). This thesis is aimed at evaluating the occurrence of persistent halogenated POPs in seven species of sub-Arctic and Arctic marine mammals over a 25-year period. The emphasis is on studying temporal variations in concentration of three categories of POPs, including naturally occurring organobromine compounds. Polybrominated diphenyl ethers (PBDEs), Metoxylated diphenyl ethers (MeO-PBDEs), and polychlorinated naphtalenes (PCNs) were extracted from blubber tissue and analyzed by GC/MS. Polyfluoroalkyl substances (PFAS) were extracted from livers and analyzed by LC-MS/MS. Although restricted by the number of pooled samples, survey points, and species available from the specimen banks, the results showed some interesting contamination patterns. Overall, pollutant concentrations showed signs of declining or levelling out, indicating a decrease in POP exposure in the studied areas in recent years. However, increasing levels of long-chain fluorinated compounds (PFCAs) present in most species is a finding of concern, and implies that a continuous monitoring of these compounds is important. Interestingly, a shift over time in the relative abundance of PFOS isomers in ringed seals was observed, indicating a change in exposure to PFOS in recent years. In many of the investigated species the MeO-PBDE levels equalled or exceeded the levels of PBDEs, showing that MeO-PBDEs can be major contributors to the organobromine load in marine mammal species. No apparent relation was found between PBDE and MeO-PBDE levels, adding further support for a natural origin of MeO-PBDEs.
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| 13. |
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| 14. |
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| 15. |
- Van Leeuwen, S. P. J., et al.
(author)
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First worldwide UNEP interlaboratory study on persistent organic pollutants (POPs), with data on polychlorinated biphenyls and organochlorine pesticides
- 2013
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In: TrAC. Trends in analytical chemistry. - : Elsevier BV. - 0165-9936 .- 1879-3142. ; 46, s. 110-117
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Journal article (peer-reviewed)abstract
- The first worldwide interlaboratory study on persistent organic pollutants (POPs) under the Stockholm Convention was organized, with a participation of 103 laboratories from Asia, Europe, the Americas, Africa and Australia, of which the majority submitted data on polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs). The participating laboratories were requested to analyze different matrices (i.e. two test solutions, and test materials for fish, sediment, fly ash and human milk). All results were statistically evaluated according to the procedures used in the European Union-based QUASIMEME proficiency-testing scheme.
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| 16. |
- Van Leeuwen, S. P. J., et al.
(author)
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POPs analysis reveals issues in bringing laboratories in developing countries to a higher quality level
- 2013
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In: TrAC. Trends in analytical chemistry. - : Elsevier BV. - 0165-9936 .- 1879-3142. ; 46, s. 198-206
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Journal article (peer-reviewed)abstract
- We assessed the performance of laboratories in 18 developing countries in analyzing persistent organic pollutants (POPs) in environmental and human samples, as part of a capacity-building program with the goal of helping laboratories increase proficiency in the types of analyses required for the POPs Global Monitoring Program (GMP) under the Stockholm Convention. We identified several issues that need improvement before the laboratories can contribute to the GMP, including technical aspects of POPs analysis, QA/QC issues and laboratory-management problems.
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| 17. |
- van Leeuwen, Stefan P. J., et al.
(author)
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Struggle for quality in determination of perfluorinated contaminants in environmental and human samples
- 2006
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In: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 40:24, s. 7854-7860
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Journal article (peer-reviewed)abstract
- The first worldwide interlaboratory study on the analyses of 13 perfluorinated compounds (PFCs) in three environmental and two human samples indicates a varying degree of accuracy in relation to the matrix or analyte determined. The ability of 38 participating laboratories from 13 countries to determine the analytes in the various matrices was evaluated by calculation of z-scores according to the Cofino model. The PFCs which were reported most frequently by the laboratories, and assessed with the most satisfactory agreement, were perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA). In general, the level of agreement between the participating laboratories decreased in the following order: PFC standard solution (76% satisfactory z-scores of <[2]1 for PFOS) < human blood (67%) < human plasma (63%) < fish liver extract (55%) < water (31%) < fish tissue (17%). This shows that relative good agreement between laboratories was obtained for the study of standard and human matrices. For the fish extract, most laboratories underestimated the actual PFOS concentration due to matrix effects. The results for the fish tissue and water are also poor, indicating that the extraction and cleanup steps require further improvement. It was concluded that the PFC determinations in various matrices are not yet fully mastered.
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