27 research outputs found
Porous Ultra-Thin Films from Photocleavable Block Copolymers: In-Situ Degradation Kinetics Study of Pore Material
On the basis of the major application for block copolymers to use them as separation membranes, lithographic mask, and as templates, the preparation of highly oriented nanoporous thin films requires the selective removal of the minor phase from the pores. In the scope of this study, thin film of polystyrene-block-poly(ethylene oxide) block copolymer with a photocleavable junction groups based on ortho-nitrobenzylester (ONB) (PS-hΜ-PEO) was papered via the spin coating technique followed by solvent annealing to obtain highly-ordered cylindrical domains. The polymer blocks are cleaved by means of a mild UV exposure and then the pore material is washed out of the polymer film by ultra-pure water resulting in arrays of nanoporous thin films to remove one block. The removal of the PEO materials from the pores was proven using the grazing-incidence small-angle X-ray scattering (GISAXS) technique. The treatment of the polymer film during the washing process was observed in real time after two different UV exposure time (1 and 4 h) in order to draw conclusions regarding the dynamics of the removal process. In-situ X-ray reflectivity measurements provide statistically significant information about the change in the layer thickness as well as the roughness and electron density of the polymer film during pore formation. 4 H UV exposure was found to be more efficient for PEO cleavage. By in-situ SFM measurements, the structure of the ultra-thin block copolymer films was also analysed and, thus, the kinetics of the washing process was elaborated. The results from both measurements confirmed that the washing procedure induces irreversible change in morphology to the surface of the thin film
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Provenance Store Evaluation
Requirements for the provenance store and access API are developed. Existing RDF stores and APIs are evaluated against the requirements and performance benchmarks. The teamâs conclusion is to use MySQL as a database backend, with a possible move to Oracle in the near-term future. Both Jena and Sesameâs APIs will be supported, but new code will use the Jena AP
Can Urban Air Mobility become reality? Opportunities, challenges and selected research results
Urban Air Mobility (UAM) is a new air transportation system for passengers
and cargo in urban environments, enabled by new technologies and integrated
into multimodal transportation systems. The vision of UAM comprises the mass
use in urban and suburban environments, complementing existing transportation
systems and contributing to the decarbonization of the transport sector.
Initial attempts to create a market for urban air transportation in the last
century failed due to lack of profitability and community acceptance.
Technological advances in numerous fields over the past few decades have led to
a renewed interest in urban air transportation. UAM is expected to benefit
users and to also have a positive impact on the economy by creating new markets
and employment opportunities for manufacturing and operation of UAM vehicles
and the construction of related ground infrastructure. However, there are also
concerns about noise, safety and security, privacy and environmental impacts.
Therefore, the UAM system needs to be designed carefully to become safe,
affordable, accessible, environmentally friendly, economically viable and thus
sustainable. This paper provides an overview of selected key research topics
related to UAM and how the German Aerospace Center (DLR) contributed to this
research in the project "HorizonUAM - Urban Air Mobility Research at the German
Aerospace Center (DLR)". Selected research results that support the realization
of the UAM vision are briefly presented.Comment: 20 pages, 7 figures, project HorizonUA
Scientific Assessment for Urban Air Mobility (UAM)
Better connecting the international research community and the International Civil Aviation Organization (ICAO) enables effective assessments of novel aviation innovations. The International Forum for Aviation Research (IFAR) created a group on Urban Air Mobility (UAM) to explore the broad array of aspects relevant to the ICAO mandate. The assessment began with a study of the current industry landscape, including an overview of existing market studies, proposed aircraft designs and concepts, and potential paths of industry evolution. The Industry Assessment is summarized into key takeaways highlighting the need for international assessments on economic and societal factors associated with UAM, common understanding of the extent to which the nascent industry can leverage current infrastructure and regulatory structures, and harmonization of industrywide terminology. The subsequent Scientific Assessment, developed through cooperative efforts between international domain experts, captures 17 focus areas relevant to UAM. All focus areas present opportunities for further research. Key takeaways include: the need for further study of the impact of autonomous systems (AS) on the industry; infrastructure requirements (including vertiports and weather sensing) to support the industry; and data requirements (including domains such as cybersecurity, emissions, and safety) to ensure safe, scalable operations. Finally, a brief overview of the current standards landscape as relevant to the Scientific Assessment is presented, which displays the benefits of applying digital systems engineering techniques to map current research efforts to ongoing standards activities
Global maps of soil temperature
Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km2 resolution for 0â5 and 5â15 cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km2 pixels (summarized from 8519 unique temperature sensors) across all the world\u27s major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (â0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications
Global maps of soil temperature
Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-kmÂČ resolution for 0â5 and 5â15 cm soil depth. These maps were created by calculating the difference (i.e., offset) between in-situ soil temperature measurements, based on time series from over 1200 1-kmÂČ pixels (summarized from 8500 unique temperature sensors) across all the worldâs major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (-0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in-situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications
Global maps of soil temperature.
Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km2 resolution for 0-5 and 5-15 cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km2 pixels (summarized from 8519 unique temperature sensors) across all the world's major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (-0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications
Distortion of Ultrathin Photocleavable Block Copolymer Films during Photocleavage and Nanopore Formation
Highly ordered block copolymer thin
films have been studied extensively
during the last years because they afford versatile self-assembled
morphologies via a bottom-up approach. They promise to be used in
applications such as polymeric membranes or templates for nanostructured
materials. Among the block copolymer structures, perpendicular cylinders
have received strong attention due to their ability to fabricate highly
ordered nanopores and nanowires. Nanopores can be created from a thin
block copolymer film upon the removal of one block by selective etching
or by dissolution of one polymer block. Here we demonstrate the utilization
of polystyrene-<i>block</i>-polyÂ(ethylene oxide) diblock
copolymer (PS-<i><i>h</i>Μ</i>-PEO) with
an <i>ortho</i>-nitrobenzyl ester (ONB) as the photocleavable
block-linker to create highly ordered thin films. Removal of the PEO
block by choosing an appropriate solvent upon photocleavage is expected
to yield arrays of nanopores decorated with functional groups, thus
lending itself to adsorption or filtration uses. While the feasibility
of this approach has been demonstrated, it is crucial to understand
the influence of removal conditions (i.e., efficiency of photocleavage
as well as best washing solvent) and to evaluate changes in the surface
topology and inner structure upon photocleavage. To this end, the
time dependence evolution of the surface morphology of block copolymer
thin films was studied using grazing-incidence small-angle X-ray scattering
(GISAXS) technique in combination with scanning probe microscopy