| 1. |
- Friedlein, Rainer, et al.
(författare)
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Electronic structure of highly ordered films of self-assembled graphitic nanocolumns
- 2003
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 68:19, s. 195414-
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Tidskriftsartikel (refereegranskat)abstract
- Highly ordered, several nanometers thick films of alkylated large planar, polycyclic aromatic hydrocarbon (PAH) molecules have been grown on semi-metallic molybdenum disulfide substrates. The films are characterized by a two-dimensional lateral arrangement of columns standing at the surface on a macroscopic scale. The self-assembly of such insulated columns of face-to-face disks with surface-induced vertical alignment has been achieved directly from solution processing. Angle-resolved photoelectron spectra revealed a highly anisotropic quasi-one-dimensional electronic structure with an extended π-electronic wave function. An intermolecular dispersion of the highest occupied band of at least 0.15 eV along the stacking direction has been measured. A partial breakdown of the concept of quasimomentum due to the finite size of the nano-objects perpendicular to the stacks is observed.
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| 2. |
- Friedlein, Rainer, et al.
(författare)
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Surface-induced vertical alignment of self-assembled supramolecular columns of large polycyclic aromatic hydrocarbons and porphyrins
- 2004
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Ingår i: Synthetic metals. - : Elsevier BV. - 0379-6779 .- 1879-3290. ; 147:01-Mar, s. 79-83
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Tidskriftsartikel (refereegranskat)abstract
- Ordered films of polycyclic aromatic hydrocarbons (PAHs) and porphyrins with functional (e.g. thiophene) side-groups are good candidates for (opto-)electronic applications where fast charge separation and transport are required. Such highly ordered thin films of PAHs, including discotic hexa-peri-hexabenzocoronene (HBC) and C-132-C-16,C-4, as well as brominated functionalized porphyrin molecules have been grown from solutions on semi-metallic molybdenum disulfide substrates and characterized by angle-resolved valence band photoelectron spectroscopy. A vertical growth of self-assembled supramolecular columns perpendicular to the basal plane of the substrate along with their lateral ordering on the surface has been achieved. Annealing made it possible to increase the structural order in the HBC columns, with molecules positioned at a regular offset from the columnar axis. This permitted the formation of extended pi-electronic states with a bandwidth of at least 0.1-0.2 eV at room temperature. (C) 2004 Elsevier B.V. All rights reserved.
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| 3. |
- Herbertsson, Lina, et al.
(författare)
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Bees increase seed set of wild plants while the proportion of arable land has a variable effect on pollination in European agricultural landscapes
- 2021
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Ingår i: Plant Ecology and Evolution. - : Societe Royale de Botanique de Belgique. - 2032-3913 .- 2032-3921. ; 154:3, s. 341-350
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Tidskriftsartikel (refereegranskat)abstract
- Background and aims: Agricultural intensification and loss of farmland heterogeneity have contributed to population declines of wild bees and other pollinators, which may have caused subsequent declines in insect-pollinated wild plants.Material and methods: Using data from 37 studies on 22 pollinator-dependent wild plant species across Europe, we investigated whether flower visitation and seed set of insect-pollinated plants decline with an increasing proportion of arable land within 1 km.Key results: Seed set increased with increasing flower visitation by bees, most of which were wild bees, but not with increasing flower visitation by other insects. Increasing proportion of arable land had a strongly variable effect on seed set and flower visitation by bees across studies.Conclusion:Factors such as landscape configuration, local habitat quality, and temporally changing resource availability (e.g. due to mass-flowering crops or honey bee hives) could have modified the effect of arable land on pollination. While our results highlight that the persistence of wild bees is crucial to maintain plant diversity, we also show that pollen limitation due to declining bee populations in homogenized agricultural landscapes is not a universal driver causing parallel losses of bees and insect-pollinated plants.
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| 4. |
- Keil, M., et al.
(författare)
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High levels of alkali-metal storage in thin films of hexa-peri-hexabenzocoronene
- 2002
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 116:24, s. 10854-10860
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Tidskriftsartikel (refereegranskat)abstract
- The results of the doping of molecular solid films of the medium-sized aromatic hydrocarbon hexa-peri-hexabenzocoronene (HBC), using lithium or sodium atoms were presented. The evolution of the valence band electronic structure was monitored by x-ray photoelectron spectroscopy and studied by ultraviolet photoelectron spectroscopy. Results indicated that n-doping depended on the type of alkali-metal atom employed and on the molecular order of the film. The smaller Li ion was found to have a stronger influence on the electronic structure than Na ions. These results revealed the potential use of the graphene materials in lithium-ion batteries with a high charge-storage capacity.
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| 5. |
- Keil, M, et al.
(författare)
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Influence of the morphology on the electronic structure of hexa-peri-hexabenzocoronene thin films
- 2000
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Ingår i: JOURNAL OF PHYSICAL CHEMISTRY B. - : American Chemical Society (ACS). - 1089-5647 .- 1520-6106 .- 1520-5207. ; 104:16, s. 3967-3975
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Tidskriftsartikel (refereegranskat)abstract
- Ultrathin films of hexa-peri-hexabenzocoronene (HBC), prepared in ultrahigh vacuum by sublimation and studied using a combination of atomic force microscopy, X-ray absorption spectroscopy, and photoelectron spectroscopy were interpreted with the help of results of quantum chemical calculations. The important role of the nature of the surface of the substrate as well as the effect of postdeposition annealing on the morphology and the subsequent electronic structure were studied. In particular, on the (0001) surfaces of highly oriented pyrolitic graphite (HOPG) or molybdenum disulfide (MoS2), there is a high degree of molecular order induced by the crystal structure of the substrate surface. When deposited at room temperature on HOPG, the molecules are epitaxially ordered, while crystals from the epitaxially ordered films nucleate and grow during heating. On oxidized silicon(001) or polycrystalline gold surfaces, only totally disordered molecular solid films are formed. The epitaxial films assume a layered structure and exhibit a graphite-like electronic structure. In particular, the relationship between electronic structure and topology is discussed. The results of these studies indicate methods for the preparation of the crystalline seeds to molecular wires.
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| 6. |
- Samori, P., et al.
(författare)
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Growth of ordered hexakis-dodecyl-hexabenzocoronene layers from solution : A SFM and ARUPS study
- 2001
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1089-5647 .- 1520-6106 .- 1520-5207. ; 105:45, s. 11114-11119
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Tidskriftsartikel (refereegranskat)abstract
- The layer growth of a polycyclic aromatic hydrocarbon moiety, hexakis-dodecyl-hexabenzocoronene (HBC-C12), from solution onto a conductive flat solid substrate has been studied. Scanning Force Microscopy (SFM), together with the analysis of the intensities of p-structures in spectra of Angle-Resolved Ultraviolet Photoelectron Spectroscopy (ARUPS) measurements, revealed that the HBC-C12 molecules can self-assemble as dry layers with the conjugated disklike molecules lying flat on the (0001) plane of highly oriented pyrolitic graphite (HOPG). By varying the rate of the molecular physisorption it was possible to orient these molecular architectures along preferential directions according to the symmetry of the substrate. Additionally, the film morphology is affected by the concentration of the solution. This indicates that the growth of these organic layers on HOPG is a kinetically governed process which, if carried out sufficiently slowly, leads to the growth of hetero-epitaxial crystallites.
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| 7. |
- Siwy, Justyna, et al.
(författare)
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CD99 and polymeric immunoglobulin receptor peptides deregulation in critical COVID-19 : A potential link to molecular pathophysiology?
- 2021
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Ingår i: Proteomics. - : John Wiley & Sons. - 1615-9853 .- 1615-9861. ; 21:20
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Tidskriftsartikel (refereegranskat)abstract
- Identification of significant changes in urinary peptides may enable improved understanding of molecular disease mechanisms. We aimed towards identifying urinary peptides associated with critical course of COVID-19 to yield hypotheses on molecular pathophysiological mechanisms in disease development. In this multicentre prospective study urine samples of PCR-confirmed COVID-19 patients were collected in different centres across Europe. The urinary peptidome of 53 patients at WHO stages 6–8 and 66 at WHO stages 1–3 COVID-19 disease was analysed using capillary electrophoresis coupled to mass spectrometry. 593 peptides were identified significantly affected by disease severity. These peptides were compared with changes associated with kidney disease or heart failure. Similarities with kidney disease were observed, indicating comparable molecular mechanisms. In contrast, convincing similarity to heart failure could not be detected. The data for the first time showed deregulation of CD99 and polymeric immunoglobulin receptor peptides and of known peptides associated with kidney disease, including collagen and alpha-1-antitrypsin. Peptidomic findings were in line with the pathophysiology of COVID-19. The clinical corollary is that COVID-19 induces specific inflammation of numerous tissues including endothelial lining. Restoring these changes, especially in CD99, PIGR and alpha-1-antitripsin, may represent a valid and effective therapeutic approach in COVID-19, targeting improvement of endothelial integrity.
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| 8. |
- Tedesco, Sara, et al.
(författare)
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High-Throughput Proteomics: A New Tool for Quality and Safety in Fishery Products
- 2014
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Ingår i: Current protein and peptide science. - : Bentham Science Publishers. - 1389-2037 .- 1875-5550. ; 15:2, s. 118-133
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Forskningsöversikt (refereegranskat)abstract
- In order to cope with the increasing demand for fishery products, sensitive technological tools are required to ensure high quality and wholesomeness and to monitor their production process in a sustainable manner while complying with the strict standards imposed by regulatory authorities. Proteomics may assist the industry as it allows an unbiased approach in the discovery of biomarkers that could be used to increase our understanding of different biological, physiological and ecological aspects that may be advantageous in optimizing quality and safety in aquatic species. The aim of this review is to highlight the potential of cost-effective high-throughput technologies, such as those offered by proteomics using "on-line" mass spectrometry to improve the efficiency of the industry in identifying biomarkers relevant for safe high quality products.
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| 9. |
- Tsao, H.N., et al.
(författare)
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From ambi- To unipolar behavior in discotic dye field-effect transistors
- 2008
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Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 20:14, s. 2715-2719
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Tidskriftsartikel (refereegranskat)abstract
- A study was conducted to demonstrate solution-processable ambipolar organic field-effect transistors based on a discotic dye. Such single component devices allow the study of the influence of supramolecular ordering on FET charge transport properties. These transistors exhibited ambipolarity even without any structural order. The absence of p-type behavior could not be explained by the increase of hole injection barrier or by interface trapping. It was rather observed that the change in morphology most probably lead to such a phenomenon. These findings further suggest that besides charge injection barriers and interface trapping, structural composition, that is, microscopic domain boundaries together with local defects in one-dimensional columnar systems, also trigger the loss of ambipolarity owing to lowering of the minority charge carrier mobility.
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| 10. |
- Zhi, L., et al.
(författare)
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Solid-state pyrolyses of metal phthalocyanines : A simple approach towards nitrogen-doped CNTs and metal/carbon nanocables
- 2005
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Ingår i: Small. - : Wiley. - 1613-6810 .- 1613-6829. ; 1:8-9, s. 798-801
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Tidskriftsartikel (refereegranskat)abstract
- Solid-state pyrolysis of organometallic precursors has emerged as an alternative method for preparing carbon nanostructures such as carbon nanotubes (CNT) and carbon anions. The morphology of the tubes can be controlled by the nature of the precursors and the pyrolysis procedures, and micrometer long nanotubes, composed of metal carbide wires encased in a graphitic sheath. Cobalt phthalocyanine (CoPc) as well as iron phthalocyanine were pyrolyzed at different temperatures to obtain CNTs. HRTEM and energy-dispersion X-Ray analysis disclosed that the core consisted of long, iron-containing single crystals and that the core was fully surrounded by crystallized graphic carbon. Iron-filled carbon nanotubes were also obtained from the pyrolysis of ferrocene by CVD method. Encapsulated iron carbide were also observed inside the carbon nanotubes formed after pyrolysis of FePc. These nanotubes and nanocables were considered useful for assembling miniaturized electronic device and sensors.
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