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- Schoch, CL, et al.
(författare)
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Nuclear ribosomal internal transcribed spacer (ITS) region as a universal DNA barcode marker for Fungi
- 2012
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 1091-6490. ; 109:16, s. 6241-6246
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Tidskriftsartikel (refereegranskat)abstract
- Six DNA regions were evaluated as potential DNA barcodes for Fungi, the second largest kingdom of eukaryotic life, by a multinational, multilaboratory consortium. The region of the mitochondrial cytochrome c oxidase subunit 1 used as the animal barcode was excluded as a potential marker, because it is difficult to amplify in fungi, often includes large introns, and can be insufficiently variable. Three subunits from the nuclear ribosomal RNA cistron were compared together with regions of three representative protein-coding genes (largest subunit of RNA polymerase II, second largest subunit of RNA polymerase II, and minichromosome maintenance protein). Although the protein-coding gene regions often had a higher percent of correct identification compared with ribosomal markers, low PCR amplification and sequencing success eliminated them as candidates for a universal fungal barcode. Among the regions of the ribosomal cistron, the internal transcribed spacer (ITS) region has the highest probability of successful identification for the broadest range of fungi, with the most clearly defined barcode gap between inter- and intraspecific variation. The nuclear ribosomal large subunit, a popular phylogenetic marker in certain groups, had superior species resolution in some taxonomic groups, such as the early diverging lineages and the ascomycete yeasts, but was otherwise slightly inferior to the ITS. The nuclear ribosomal small subunit has poor species-level resolution in fungi. ITS will be formally proposed for adoption as the primary fungal barcode marker to the Consortium for the Barcode of Life, with the possibility that supplementary barcodes may be developed for particular narrowly circumscribed taxonomic groups.
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- Lange, Jonathan, et al.
(författare)
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Novel lithographic printing techniques enabling sustainable and high quality multi material manufacturing process for future space outposts
- 2021
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Ingår i: IAC 2021 Congress Proceedings, 72nd International Astronautical Congress (IAC), Dubai, United Arab Emirates. - : International Astronautical Federation (IAF).
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Konferensbidrag (refereegranskat)abstract
- Several challenges remain before the full potential of on-orbit manufacturing can be realized. There may be some limitations to the types of items that can be manufactured in space. Such limitations could be caused by a variety of factors, including the materials required for a particular structure, the size of the object to be manufactured, the time required to execute the architecture, the configuration of the object being manufactured, and the raw material needed to support the manufacturing process. The complementary challenge to the relevant fabrication processes is the possibility to achieve the required precision demanded by geometrically complex structures and the ability to be versatile in processing a broad material spectrum. In this context, novel lithographic 3D printing techniques will be an asset to pave the way towards overcoming these challenges. Currently, the European Space Agency (ESA) is investigating the implementation of such technology in the context of a lunar base. In particular, two different applications are being studied: • Lithography-Based Ceramic Manufacturing (LCM), where the ceramic powder is distributed in a photocurable monomer formulation in presence of a photoinitiator. Ceramic materials are extensively used in a vast number of technological processes as well as in space applications. They are usually considered as the material of choice for applications where other materials such as plastic and metal fail to deliver the required performance. The LCM process will also allow processing lunar regolith simulant adding value to the current material portfolio of this technique, as well as to the range of processes potentially applicable on the lunar or Martian surface. • Lithography-based Metal Manufacturing (LMM) for processing metallic powders. In contrast to the currently predominantly used powder bed fusion (direct metal laser melting) techniques, this process uses a paste/suspension as feedstock and hence, does not rely on the use of highly spherical gas atomized powders. This will enable the utilization of recycled powders from scrap metals that are available at Moon bases or of metallic alloys reduced from lunar regolith, thus providing higher flexibility in accepting raw material with poor quality and purity. The paper addresses the results from both activities in terms of printed parts quality (roughness, density, resolution and accuracy) as well as the implementation requirements for the whole process chain, including suitable pre- and post-processing steps, with the aim to achieve a zero-waste flow in a lunar environment.
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- Almers, Peter, et al.
(författare)
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Survey of channel and radio propagation models for wireless MIMO systems
- 2007
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Ingår i: Eurasip Journal on Wireless Communications and Networking. - : Springer Science and Business Media LLC. - 1687-1472 .- 1687-1499. ; 2007
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Tidskriftsartikel (refereegranskat)abstract
- This paper provides an overview of the state-of- the-art radio propagation and channel models for wireless multiple-input multiple-output (MIMO) systems. We distinguish between physical models and analytical models and discuss popular examples from both model types. Physical models focus on the double-directional propagation mechanisms between the location of transmitter and receiver without taking the antenna configuration into account. Analytical models capture physical wave propagation and antenna configuration simultaneously by describing the impulse response (equivalently, the transfer function) between the antenna arrays at both link ends. We also review some MIMO models that are included in current standardization activities for the purpose of reproducible and comparable MIMO system evaluations. Finally, we describe a couple of key features of channels and radio propagation which are not sufficiently included in current MIMO models. Copyright c 2007 P. Almers et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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- Goetz, Katelyn P., et al.
(författare)
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Remarkable performance recovery in highly defective perovskite solar cells by photo-oxidation
- 2023
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Ingår i: Journal of Materials Chemistry C. - : Royal Society of Chemistry (RSC). - 2050-7526 .- 2050-7534. ; 11:24, s. 8007-8017
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Tidskriftsartikel (refereegranskat)abstract
- Exposure to environmental factors is generally expected to cause degradation in perovskite films and solar cells. Herein, we show that films with certain defect profiles can display the opposite effect, healing upon exposure to oxygen under illumination. We tune the iodine content of methylammonium lead triiodide perovskite from understoichiometric to overstoichiometric and expose them to oxygen and light prior to the addition of the top layers of the device, thereby examining the defect dependence of their photooxidative response in the absence of storage-related chemical processes. The contrast between the photovoltaic properties of the cells with different defects is stark. Understoichiometric samples indeed degrade, demonstrating performance at 33% of their untreated counterparts, while stoichiometric samples maintain their performance levels. Surprisingly, overstoichiometric samples, which show low current density and strong reverse hysteresis when untreated, heal to maximum performance levels (the same as untreated, stoichiometric samples) upon the photooxidative treatment. A similar, albeit smaller-scale, effect is observed for triple cation and methylammonium-free compositions, demonstrating the general application of this treatment to state-of-the-art compositions. We examine the reasons behind this response by a suite of characterization techniques, finding that the performance changes coincide with microstructural decay at the crystal surface, reorientation of the bulk crystal structure for the understoichiometric cells, and a decrease in the iodine-to-lead ratio of all films. These results indicate that defect engineering is a powerful tool to manipulate the stability of perovskite solar cells.
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