1,720,966 research outputs found
Een open oligarchie? De machtsstructuur in de Antwerpse magistraat tijdens de periode 1520-1555
No full textWouters Koen. Een open oligarchie? De machtsstructuur in de Antwerpse magistraat tijdens de periode 1520-1555. In: Revue belge de philologie et d'histoire, tome 82, fasc. 4, 2004. Histoire médiévale, moderne et contemporaine - Middeleeuwse. moderne en hedendaagse geschiedenis. pp. 905-934
Cable bacteria as electronic biological materials: Towards use in biodegradable electronics
No full textIn modern times, electrical devices have become ingrained with our society. These devices form a major role in communication, leisure and even survival. However, as these devices break and get replaced by newer versions, over 50 million tonnes of electronic waste that is not recycled is generated yearly. Whilst in the long run this will undoubtedly have ecological consequences, in developing countries this already forms a threat to the health of adults and children, even before birth. As the global demand for electronics seems to be ever increasing, it is evident that biodegradable alternatives need to be found.
Approximately a decade ago, at the coast of Denmark, long filamentous bacteria were discovered that were found to conduct electricity over centimetre scale distances. The research in this thesis aims to gain more insight into the conductive properties of these bacteria and study the potential of these bacteria to be used as alternatives to the non-biodegradable wires in electronic circuits. The basics of electron transport are well-known for crystalline materials and can be used to create electronic devices, and various models exist for non-crystalline materials (chapter 1.1). Meanwhile, whilst properties such as structure, metabolism and respiration have commonalities in various bacteria (chapter 1.2), some break the mould by bringing electrons out of the cell for their respiration (chapter 1.3). Cable bacteria go one step further by forming chains of tens of thousands of cells that work together to survive (chapter 1.4). These chains transport electrons through wires that are interconnected between the cells. This way, these bacteria thrive in the sediment by stretching out between sulphide in the bottom layers and oxygen at the top.
In order to gain more insight into the charge transport properties of cable bacteria, various techniques were employed in this thesis (chapter 2). Through direct conductivity measurements it was found that various electrodes can be used in order to attach the bacteria in a circuit. However, the conductivity of these bacteria decreases under exposure to ambient air and light. Meanwhile, fluorescence microscopy revealed autofluorescence in these bacteria. Nanoscale electronic measurements are used to gain more insights into the connecting structures between the fibres of the bacteria. Finally, using mass spectrometry on different strains of cable bacteria, it was found that nickel and sulphur are common elements in the conductive fibres of these bacteria.
How do cable bacteria compare to other biodegradable alternatives for electronics that have been found so far? This search has already found various materials with interesting properties by looking at nature (chapter 3). These materials can be used in the device as either the conductive structure, the substrate or as an encapsulating layer to change the lifetime of the devices. In the world of electromicrobiology, electroactive bacteria such as Geobacter and Shewanella, which produce conductive nanowires, form interesting candidates. Through the study of the proteins and genetic modification, the conductivity of these nanowires can be improved, though the conduction lengths are limited to the micrometre range. Meanwhile, cable bacteria already have conductivities comparable to the previously found biodegradable electronics, with conduction lengths in the range of centimetres. These results may improve even further as more research is done on these bacteria. However, hurdles such as the isolation of the conductive fibres need to be passed before these bacteria can be used in electronics.
In order to study the signal transmission properties in cable bacteria, the response to periodic signals was analysed. On the one hand, sinewaves were used for impedance spectroscopy. A new model that considers the microscopic structure of the conductive pathways was proposed that gave a better match to the experimental data than the previous model. On the other hand, square waves were sent through the bacteria in order to simulate a digital signal. Even with the simplified model, the theoretical predictions could be fitted to the experimental data. Based on this data it was concluded that cable bacteria could transmit sinewave and square wave electrical signals in the investigated frequency range up to 500 kHz. This was demonstrated by sending an analog music signal through a cable bacteria filament.
From the results obtained in this thesis, it is clear that cable bacteria can be considered as electrical interconnects allowing the transmission of electrical signals in a broad frequency range and therefore have the intrinsic potential to be used as biological electronic components in biohybrid electronics, biodegradable electronics, and other future e-biologics applications. The high conductivity values and good connections cable bacteria form with various electrodes makes it easy to integrate these bacteria in a circuit. However, once integrated, care should be taken to prevent exposure to ambient air or light as these degrade the conductivity of the bacteria.
Since these bacteria are capable of transmitting information, maybe one day cable bacteria or other electroactive bacteria could be used to transmit the message that global e-waste is decreasing
Biomaterials and Electroactive Bacteria for Biodegradable Electronics
No full textThe global production of unrecycled electronic waste is extensively growing each year, urging the search for alternatives in biodegradable electronic materials. Electroactive bacteria and their nanowires have emerged as a new route toward electronic biological materials (e-biologics). Recent studies on electron transport in cable bacteria—filamentous, multicellular electroactive bacteria—showed centimeter long electron transport in an organized conductive fiber structure with high conductivities and remarkable intrinsic electrical properties. In this work we give a brief overview of the recent advances in biodegradable electronics with a focus on the use of biomaterials and electroactive bacteria, and with special attention for cable bacteria. We investigate the potential of cable bacteria in this field, as we compare the intrinsic electrical properties of cable bacteria to organic and inorganic electronic materials. Based on their intrinsic electrical properties, we show cable bacteria filaments to have great potential as for instance interconnects and transistor channels in a new generation of bioelectronics. Together with other biomaterials and electroactive bacteria they open electrifying routes toward a new generation of biodegradable electronics
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
ESA–BEXUS project: OSCAR - Zonne-Energie Voor De Planeet Aarde En Verder
No full textZonne–energie is ontegensprekelijk één van de belangrijkste en duurzaamste oplossingen voor de globale energie– en klimaatuitdagingen waar onze planeet voor staat. Nieuwe generatie printbare, plooibare en ultra–dunnen zonnecellen kunnen bovendien leiden tot tal van nieuwe toepassingen, gaande van energie–bevoorrading voor draag bare elektronica (smartphones, tablets, …) tot grensverleggende toepassingen voor toekomstige ruimtereizen. Printbare organische en perovskiet–zonnecellen zijn namelijk de wereldkampioenen qua verhouding energie–opbrengst versus gewicht. Voor toekomstige ruimtevaartmissies hebben deze zonnecellen dus de bijzondere voordelen dat ze een ultra–licht gewicht hebben, plooibaar en uitvouwbaar zijn en bovendien ter plaatse (in ruimteschepen of in ruimtestations op bijvoorbeeld de Maan of op Mars) kunnen geprint worden.
Door deelname aan het BEXUS–programma (Balloon Experiments for University Students) van de Europese ruimtevaartorganisatie ESA, hebben een team van negen UHasselt–doctoraatstudenten en studenten Fysica (Miguel–Angel Beynaerts, Ilaria Cardinaletti, Rob Cornelissen, Jaroslav Hruby, Steven Nagels, Dieter Schreurs, Jelle Vodnik, Tim Vangerven & Koen Wouters) een wereldrecord gebroken qua gebruik van printbare zonnecellen op grote hoogte. Met het OSCAR–project (Optical Sensors based on CARbon Materials) hebben ze voor het eerste de prestaties van printbare zonnecellen en van een nieuwe magnetische–veldsensor bestudeerd in echte ruimtevaartcondities. Vanuit het lanceerstation Kiruna in Zweden werd een onderzoeksballon in de stratosfeer gebracht — op 32 kilometer hoogte (3x hoogte van vliegtuigtrajecten) — waarbij extreme condities heersen zoals lage luchtdruk, lage temperaturen (tot wel –60 graden Celsius) en een pak meer straling van de zon
ESA–BEXUS project: OSCAR - Zonne-Energie Voor De Planeet Aarde En Verder
No full textZonne–energie is ontegensprekelijk één van de belangrijkste en duurzaamste oplossingen voor de globale energie– en klimaatuitdagingen waar onze planeet voor staat. Nieuwe generatie printbare, plooibare en ultra–dunnen zonnecellen kunnen bovendien leiden tot tal van nieuwe toepassingen, gaande van energie–bevoorrading voor draag bare elektronica (smartphones, tablets, …) tot grensverleggende toepassingen voor toekomstige ruimtereizen. Printbare organische en perovskiet–zonnecellen zijn namelijk de wereldkampioenen qua verhouding energie–opbrengst versus gewicht. Voor toekomstige ruimtevaartmissies hebben deze zonnecellen dus de bijzondere voordelen dat ze een ultra–licht gewicht hebben, plooibaar en uitvouwbaar zijn en bovendien ter plaatse (in ruimteschepen of in ruimtestations op bijvoorbeeld de Maan of op Mars) kunnen geprint worden.
Door deelname aan het BEXUS–programma (Balloon Experiments for University Students) van de Europese ruimtevaartorganisatie ESA, hebben een team van negen UHasselt–doctoraatstudenten en studenten Fysica (Miguel–Angel Beynaerts, Ilaria Cardinaletti, Rob Cornelissen, Jaroslav Hruby, Steven Nagels, Dieter Schreurs, Jelle Vodnik, Tim Vangerven & Koen Wouters) een wereldrecord gebroken qua gebruik van printbare zonnecellen op grote hoogte. Met het OSCAR–project (Optical Sensors based on CARbon Materials) hebben ze voor het eerste de prestaties van printbare zonnecellen en van een nieuwe magnetische–veldsensor bestudeerd in echte ruimtevaartcondities. Vanuit het lanceerstation Kiruna in Zweden werd een onderzoeksballon in de stratosfeer gebracht — op 32 kilometer hoogte (3x hoogte van vliegtuigtrajecten) — waarbij extreme condities heersen zoals lage luchtdruk, lage temperaturen (tot wel –60 graden Celsius) en een pak meer straling van de zon
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