Lasergestützte Modifikation von Lithiummanganoxid und Lithiumnickelmangankobaltoxid

Es wurden lasergestützte Strukturierungskonzepte und Wärmebehandlungsverfahren entwickelt, um Mikrostrukturen in Lithiummanganoxid-Dünnschichten einzubringen und eine batterieaktive Phase einzustellen. Strukturierungsprozesse wurden erfolgreich auf Dickschichtelektroden übertragen. Hierbei wurden Mikrokanäle erzeugt, die eine stark beschleunigte Elektrolytbenetzung bewirken. Die elektrochemische Lebensdauer von Zellen mit laserstrukturierten Elektroden konnte erheblich verbessert werden

Heat transfer challenge and design evaluation for a multi-stage temperature swing adsorption (TSA) process

Functionalized solid amine-based temperature swing adsorption (TSA) processes have recently been proposed as a potential way to reduce the energy-penalty of post-combustion carbon capture processes (1). If TSA is to be carried out at large scale and with high energy-efficiency, continuously operated counter-current contactors are required for thermodynamic reasons. This could, generally, be achieved by using moving bed contactors. However, the heat exchange requirement of TSA is significant and heat transfer is poor in fixed and moving beds. Therefore, multi-stage fluidized bed contactors with counter-current flow of solids and gas phase and immersed heat exchange surfaces may solve the heat transfer challenge while maintaining the thermodynamic process requirements. Experiments have shown that adsorption and desorption kinetics of suitable functionalized amine sorbents are fast and equilibrium loadings are practically reached in the stages (1). Thus, heat exchange is the dominant limiting factor for a practical stage design in multi-stage fluidized bed TSA. The present work rationally develops design requirements for TSA stages based on the necessary heat exchange rates. The considered particles are Geldart Type B (diameter 200-300 µm, particle density 1000-1500 kg/m3). Scalability of the design proposal is considered and vertically orientated heat exchanger tubes are compared to horizontal tube bundles. The net movement and mixing of particles within the bubbling bed stage must be maintained in spite of the emulsified heat exchangers (possible dead zones in the area of the tube bundles). It is shown that the pressure drop of multi-stage fluidized bed TSA units for flue gas CO2 capture is practically determined by the heat exchange requirement and not by the space-time of the solids for the adsorption. Future work will employ a bubbling fluidized bed heat exchange testing device for optimization of the heat exchanger geometry with respect to heat transfer rates and particle residence time distribution in the stage. Heat exchange measurement devices have been presented recently in literature for horizontal tube bundles and Geldart Type A particles (2), but the importance of the heat exchanger issue in continuous fluidized bed TSA requires the detailed investigation for the Geldart B range, potentially considering the macroscopic particle movement relative to the heat exchangers within each individual TSA stage. Please click Additional Files below to see the full abstract

Performance of a NiO-based oxygen carrier for chemical looping combustion and reforming in a 120 kW unit

AbstractIn this study the performance of two different Ni-based oxygen carriers in a 120kW chemical looping pilot rig at Vienna University of Technology is presented. A dual circulating fluidized bed (DCFB) system has been designed with the important characteristics of high solid circulation, very low residence times and a high power to solid inventory ratio. For all presented results the pilot rig is fueled with methane at 140kW fuel power. For both oxygen carriers high CH4 conversion and CO2 yield is achieved. Air to fuel ratio and temperature are varied. CH4 conversion at higher air to fuel ratio as well as at higher temperature seems to decrease. This phenomenon is linked to the Ni/NiO ratio of the particle which determines the catalytic activity and thus influences the CH4 conversion and the CO2 yield

Prevalence of RT-qPCR-detected SARS-CoV-2 infection at schools: First results from the Austrian School-SARS-CoV-2 prospective cohort study.

BACKGROUND: The role of schools in the SARS-CoV-2 pandemic is much debated. We aimed to quantify reliably the prevalence of SARS-CoV-2 infections at schools detected with reverse-transcription quantitative polymerase-chain-reaction (RT-qPCR). METHODS: This nationwide prospective cohort study monitors a representative sample of pupils (grade 1-8) and teachers at Austrian schools throughout the school year 2020/2021. We repeatedly test participants for SARS-CoV-2 infection using a gargling solution and RT-qPCR. We herein report on the first two rounds of examinations. We used mixed-effects logistic regression to estimate odds ratios and robust 95% confidence intervals (95% CI). FINDINGS: We analysed data on 10,734 participants from 245 schools (9465 pupils, 1269 teachers). Prevalence of SARS-CoV-2 infection increased from 0·39% at round 1 (95% CI 028-0·55%, 28 September-22 October 2020) to 1·39% at round 2 (95% CI 1·04-1·85%, 10-16 November). Odds ratios for SARS-CoV-2 infection were 2·26 (95% CI 1·25-4·12, P = 0·007) in regions with >500 vs. ≤500 inhabitants/km2, 1·67 (95% CI 1·42-1·97, P<0·001) per two-fold higher regional 7-day community incidence, and 2·78 (95% CI 1·73-4·48, P<0·001) in pupils at schools with high/very high vs. low/moderate social deprivation. Associations of regional community incidence and social deprivation persisted in a multivariable adjusted model. Prevalence did not differ by average number of pupils per class nor between age groups, sexes, pupils vs. teachers, or primary (grade 1-4) vs. secondary schools (grade 5-8). INTERPRETATION: This monitoring study in Austrian schools revealed SARS-CoV-2 infection in 0·39%-1·39% of participants and identified associations of regional community incidence and social deprivation with higher prevalence. FUNDING: BMBWF Austria

Sensitivity and specificity of the antigen-based anterior nasal self-testing programme for detecting SARS-CoV-2 infection in schools, Austria, March 2021.

This study evaluates the performance of the antigen-based anterior nasal screening programme implemented in all Austrian schools to detect SARS-CoV-2 infections. We combined nationwide antigen-based screening data obtained in March 2021 from 5,370 schools (Grade 1-8) with an RT-qPCR-based prospective cohort study comprising a representative sample of 244 schools. Considering a range of assumptions, only a subset of infected individuals are detected with the programme (low to moderate sensitivity) and non-infected individuals mainly tested negative (very high specificity)

A microarray analysis of two distinct lymphatic endothelial cell populations

We have recently identified lymphatic endothelial cells (LECs) to form two morphologically different populations, exhibiting significantly different surface protein expression levels of podoplanin, a major surface marker for this cell type. In vitro shockwave treatment (IVSWT) of LECs resulted in enrichment of the podoplaninhigh cell population and was accompanied by markedly increased cell proliferation, as well as 2D and 3D migration. Gene expression profiles of these distinct populations were established using Affymetrix microarray analyses. Here we provide additional details about our dataset (NCBI GEO accession number GSE62510) and describe how we analyzed the data to identify differently expressed genes in these two LEC populations

How to Optimize Carbon Sinks and Biodiversity in the Conversion of Norway Spruce to Beech Forests in Austria?

Assessments of synergies and trade-offs between climate change mitigation and forest biodiversity conservation have focused on set-aside areas. We evaluated a more comprehensive portfolio of silvicultural management adaptations to climate change and conservation measures exemplary for managed European beech forests. Based on the available literature, we assessed a range of common silvicultural management and conservation measures for their effects on carbon sequestration in forest and wood products and for substituting more carbon-intensive products. We complemented this review with carbon sequestration simulations for a typical mountainous beech forest region in Austria. We propose three priority actions to enhance the synergies between climate change mitigation and biodiversity. First, actively increase the proportion of European beech in secondary Norway spruce forests, even though beech will not be unaffected by expected water supply limitations. Secondly, optimize the benefits of shelterwood systems and promote uneven-aged forestry, and thirdly, enhance mixed tree species. Targeted conservation measures (deadwood, habitat trees, and old forest patches) increase the total C storage but decrease the annual C sequestration in forests, particularly in wood products. The establishment of a beech wood market with an extended product portfolio to reduce the use of fuelwood is essential for sustainable climate change mitigation. Since there are limitations in the production of saw timber quality beech wood on low fertility sites, C accumulation, and biodiversity can be emphasized in these areas

Operating experience with chemical looping combustion in a 120 kW dual circulating fluidized bed (DCFB) unit

AbstractIn this study, first operating experience with a 120 kW chemical looping pilot rig is presented. The dual circulating fluidized bed reactor system and its auxiliary units are discussed. Two different oxygen carries, i.e. ilmenite, which is a natural iron titanium ore and a designed Ni-based particle, are tested in the CLC unit. The pilot rig is fueled with H2, CO and CH4 respectively at a fuel power of 65–145 kW. High solids circulation, very low solids residence time and low solids inventory are observed during operation. Due to the scalability of the design concept, these characteristics should be quite similar to those of commercial CLC power plants. Ilmenite shows a high potential for the combustion of H2 rich gases (e.g. from coal gasification with steam). The H2 conversion is quite high but there is still a high potential for further improvement. The Ni-based oxygen carrier achieves the thermodynamic maximum H2 and CO conversion and also very high CH4 conversion. A variation of the air/fuel ratio and the reaction temperature indicates that the Ni/NiO ratio of the particle has a high influence on the performance of the chemical looping combustor

A light-weight framework for location-based services

Context-aware mobile systems aim at delivering information and services tailored to the current user’s situation [1], [10]. One major application area of these systems is the tourism domain, assisting tourists especially during their vacation through location-based services (LBS) [4], [7]. Consequently a proliferation of approaches [2], [5], [8], [9], [12], [15], [17], [18] can be observed, whereby an in-depth study of related work has shown that some of these existing mobile tourism information systems exhibit few limitations [3], [19]: First, existing approaches often use proprietary interfaces to other systems (e.g. a Geographic Information System – GIS), and employ their own data repositories, thus falling short in portability and having to deal with time consuming content maintenance. Second, often thick clients are used that may lack out-of-the-box-usage. Third, existing solutions are sometimes inflexible concerning configuration capabilities of the system. To deal with those deficiencies, we present a lightweight framework for LBS that can be used for various application domains. This framework builds on existing GIS standards, incorporates already available Web content, can be employed out-of-the-box, and is configurable by usin