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    Synthesis and Characterization of Nanoporous Resin Particles for Water Purification

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    Through progressive industrialization and the relentless consumption of natural raw materials, man is exerting a negative influence on his habitat. In particular, water as the basis of life and almost all processes of our economy is contaminated by various pollutants due to excessive use and insufficient purification. Here, oxyanions, heavy metal ions and organic pollutants pose a high risk to aquatic habitats and ultimately to humans. Due to insufficient removal, they also contribute to the loss of non-renewable raw materials for industrial cycles. Due to a mostly low effect concentration and potential interactions with diverse living organisms, the removal of many contaminants is extremely important to avoid further altering existing ecosystems. Adsorption represents an energy-efficient method of removal using adsorbents suitable for this purpose. Highly cross-linked resin polymers such as poly(melamine-co-formaldehyde) (PMF) with its excellent chemical resistance, high number of functional groups and ease of preparation, represent promising starting points for adsorbents. This dissertation describes the colloidal aqueous synthesis of nanoporous resin particles (e.g. PMF) by templating with SiO2 nanoparticles (SiO2 NPs), which are subsequently used to adsorb water pollutants. An overall goal of this work consists of elucidating the mechanism for particle and pore formation by systematically varying various synthesis parameters. Electron microscopy, N2-soprtion and particle size measurement are used to analyze the morphology, size and pore structure of the particles. Comprehensive investigations thus allow to determine the influence of each tested synthesis parameter on these properties. A very important goal, especially for future large-scale applicability, is the colloidal production of uniform particles, which have both a high ordered porosity and particle diameters in the range of a few micrometers. This enables an application as a fixed-bed adsorber that can be flowed through. This goal is closely linked to the mechanistic elucidation of pore and particle formation in the synthesis. The prepared nanoporous PMF particles were tested for various adsorption applications after their characterization. In order to obtain a comprehensive picture of the applicability of PMF particles, experiments with oxyanions, with pharmaceuticals as representatives of organic pollutants and with heavy metal ions will be carried out respectively. On the one hand, these experiments will focus on investigating the adsorption performance and mechanism of PMF with the respective pollutant. On the other hand, the influence of the changed porosity on the adsorption mechanism is investigated by using different particles of a varied synthesis parameter. Sulfate and phosphate ions were investigated in the oxyanion class. Extremely high separation rates were demonstrated for both ions, significantly outperforming previous commercially available materials. In experiments concerning a potential selective adsorption and thus separation of both species, the PMF/SiO2 hybrid particles, in which the template had not yet been removed, showed a selective sulfate adsorption. The immobilization of heavy metal ions was analyzed with special focus on the simultaneous separation of the Cu2+ ions and respective anions used here. Investigations of the adsorbent after the adsorption experiments by means of electron microscopy, X-ray scattering and electron spin resonance spectroscopy elucidated the adsorption mechanism, which had been insufficiently analyzed so far. Here, adsorption and surface-induced precipitation were identified as partially separate subprocesses, both of which are responsible for the separation of both metal and anions from solution. In adsorption experiments with the monovalent ions nitrate and chloride, a two-step uptake process was identified, which was mathematically described for the first time via a new adsorption isotherm. In the scope of organic water pollutants, the separation of the pharmaceutical diclofenac is being tested. In particular, the adsorption of pharmaceuticals is an urgent issue due to their low effect concentration and ubiquity in surface and tap waters. Pharmaceutical separation using PMF has hardly been investigated worldwide despite its promising properties. In these experiments, particles templated with SiO2 NPs of different sizes and stabilized in different ways were tested. This resulted in pore systems that varied from each other especially in their accessibility of the pore system and in the diameter of the connecting channels between the main cavities. These characteristics significantly affected the adsorption capacity and separation rates in low concentration range. A final goal is to synthesize a resin network that uses an equally highly functional triazine-based monomer instead of melamine. The monomer 2,4,6-tris(2,4,6-trihydroxyphenyl)-1,3,5-triazine (3PT) possesses nine hydroxyl groups each, whereby a polymer based on it should exhibit strongly modified adsorption properties compared to PMF. This monomer was used in an aqueous polymerization analogous to PMF to produce a previously unknown polymer network, which was designated P(3PT-F). Here, templating was omitted because the newly prepared material already exhibited intrinsic nanoporosity due to the size of the 3PT monomer. In subsequent adsorption experiments, very high separation rates were demonstrated for the toxic metal ions Pb2+, Cd2+ and Ni2+. In realistic initial concentrations, the contamination was reduced to drinking water quality in each case. P(3PT-F) also showed highly selective removal of Pb2+ over the common ions Ca2+, Mg2+, K+ and Fe2+. As fundamental evidence, reusability was also demonstrated by complete desorption with dilute HCl and subsequent re-adsorption without significant reduction in capacity. Overall, starting from the fundamental study of PMF particle synthesis, a more general understanding of aqueous dispersion polymerization of hydrophobic resins was first derived and templating with hydrophilic SiO2 NPs was implemented. With the help of understanding the particle growth processes and interactions responsible for templating, the properties of the resulting particles could be controlled. Subsequently, the influence of the changed porosity in particular on the separation performance could be investigated in the adsorption studies. In addition, it was possible to analyze which interactions PMF enters into with the respective pollutant types. By replacing the monomer melamine with a hydroxyl-containing monomer, a novel resin polymer could be produced. With its altered porosity and reactivity, this can now serve as a new starting point for adsorption experiments with strongly altered adsorption performance, e.g. towards heavy metal ions.:Abstract 1 Kurzfassung 5 List of Publications 9 First-Author Publications 9 Co-Author Publications 10 Patent 12 Conference Proceedings 12 Oral Presentations 12 Poster 12 List of Figures 13 Mesoporous Poly(Melamine-co-Formaldehyde) Particles for Efficient and Selective Phosphate and Sulfate Removal: 14 Tuning the Pore Structure of Templated Mesoporous Poly(melamine-co-formaldehyde) Particles toward Diclofenac Removal: 15 Adsorption vs. Surface Precipitation of Cu²+ onto Porous Poly(melamine-co-formaldehyde) Particles: 16 SiO2 Nanospheres as Surfactant and Template in Aqueous Dispersion Polymerizations Yielding Nanoporous Resin Particles: 18 Waterborne Phenolic, Triazine-Based Porous Polymer Particles for the Removal of Nickel, Cadmium, and Lead Ions: 19 List of Tables 21 Mesoporous Poly(Melamine-co-Formaldehyde) Particles for Efficient and Selective Phosphate and Sulfate Removal: 21 Tuning the Pore Structure of Templated Mesoporous Poly(melamine-co-formaldehyde) Particles toward Diclofenac Removal: 21 Adsorption vs. Surface Precipitation of Cu²+ onto Porous Poly(melamine-co-formaldehyde) Particles: 22 SiO2 Nanospheres as Surfactant and Template in Aqueous Dispersion Polymerizations Yielding Nanoporous Resin Particles: 22 Waterborne Phenolic, Triazine-Based Porous Polymer Particles for the Removal of Nickel, Cadmium, and Lead Ions: 23 Abbreviations 25 Symbols 26 1. Introduction 1 2. Objectives and Experimental Design 5 3. Scientific Background 11 3.1. Poly(melamine-co-formaldehyde) 11 3.1.1. Polymerization Mechanism 11 3.1.2. Synthesis Strategies for the Preparation of Porous PMF Particles. 13 3.1.3. Fields of Application of PMF 13 3.2. Adsorption 15 3.2.1. Adsorption Isotherms and Mathematical Modeling 16 3.3. Surface Precipitation 20 4. Fundamentals of Instrumental Analytics 23 4.1. Gas Sorption Measurements 23 4.1.1. Determination of Pore Sizes 26 4.1.2. Determination of Specific Surface Area 27 4.2. Transmission Electron Microscopy 29 4.3. Inductively Coupled Plasma Optical Emission Spectroscopy 31 Results and Discussion 33 Chapter Overview 33 5. Mesoporous Poly(Melamine-co-Formaldehyde) Particles for Efficient and Selective Phosphate and Sulfate Removal 37 Graphical Abstract 37 Abstract 37 1. Introduction 38 2. Results and Discussion 39 2.1. Synthesis and Characterization of the PMF Particles 40 2.2. Sorption Experiments 47 3. Materials and Methods 54 3.1. Materials 54 3.2. Methods 54 3.3. Synthesis of the PMF Particles 56 3.4. Water Treatment Experiments 57 4. Conclusions 59 6. Tuning the Pore Structure of Templated Mesoporous Poly(melamine-co-formaldehyde) Particles toward Diclofenac Removal 65 Graphical Abstract 65 Abstract 65 1. Introduction 66 2. Materials 68 3. Methods 68 3.1. Synthesis of the PMF particles 70 3.2. Water treatment experiments with diclofenac solution 72 3.3. Theoretical model 72 3. Results and Discussion 73 3.1. Synthesis and characterization of the PMF particles 74 3.2. Adsorption of Pharmaceutics 80 4. Conclusion 84 7. Adsorption vs. Surface Precipitation of Cu²+ onto Porous Poly(melamine-co-formaldehyde) Particles 89 Graphical Abstract 89 Abstract 89 1. Introduction 90 2. Materials and methods 91 2.1. Materials 91 2.2. Synthesis of the Poly(melamine-co-formaldehyde) particles 92 2.3. Methods 93 2.4. Water treatment experiments 96 3. Results and discussion 97 3.1. Synthesis and characterization of the PMF particles 98 3.2. Cu2+ uptake experiments 102 3.3. Mechanism for Cu2+ and Anion Removal 115 3.4. Investigation of other heavy metal salts 116 4. Conclusions 117 8. SiO₂ Nanospheres as Surfactant and Template in Aqueous Dispersion Polymerizations Yielding Nanoporous Resin Particles 121 Graphical Abstract 121 Abstract 121 1. Introduction 122 2. Materials and methods 123 2.1. Materials 123 2.2. Methods 124 2.3. Synthesis of the PMF particles 125 2.4. Water treatment experiments 128 2.5. Theoretical model 129 3. Results and Discussion 132 3.1. PMF-Std 133 3.2. Influence of the reaction mixture composition 136 3.3. Variation of the process parameters 140 3.4. Conclusion on the templating mechanism for PMF-Std 146 3.5. Acquiring µm-sized porous PMF particles for adsorption application 149 3.6. Adsorption experiments with K2Cr2O7 solution 151 4. Conclusion 155 9. Waterborne Phenolic, Triazine-Based Porous Polymer Particles for the Removal of Nickel, Cadmium, and Lead Ions 161 Graphical Abstract 161 Abstract 161 1. Introduction 162 2. Materials and methods 163 2.1. Materials 163 2.2. Synthesis 164 2.3. Characterization 166 2.4. Batch adsorption experiments 169 2.5. Calculation and theoretical models 170 3. Results and discussion 172 3.1. Synthesis and characterization of the polymer particles 172 3.2. Adsorption experiments with Ni2+, Cd2+, and Pb2+ onto P(3PT-F)-3L 178 4. Conclusions 184 10. Conclusion and Outlook 191 Contribution to Publications 197 Mesoporous Poly(Melamine-co-Formaldehyde) Particles for Efficient and Selective Phosphate and Sulfate Removal 197 Tuning the Pore Structure of Templated Mesoporous Poly(melamine-co-formaldehyde) Particles toward Diclofenac Removal 198 Adsorption vs. Surface Precipitation of Cu²+ onto Porous Poly(melamine-co-formaldehyde) Particles 199 SiO₂ Nanospheres as Surfactant and Template in Aqueous Dispersion Polymerizations Yielding Nanoporous Resin Particles 200 Waterborne Phenolic, Triazine-Based Porous Polymer Particles for the Removal of Nickel, Cadmium, and Lead Ions 201 Danksagung 203 Appendix 205 References 207 Eidesstattliche Versicherung 217Durch fortschreitende Industrialisierung und den schonungslosen Verbrauch natürlicher Rohstoffe übt der Mensch negativen Einfluss auf seinen Lebensraum aus. Insbesondere Wasser als Grundlage des Lebens und fast aller Prozesse unserer Wirtschaft wird durch eine übermäßige Nutzung und unzureichende Reinigung mit diversen Schadstoffen kontaminiert. Hierbei stellen Oxyanionen, Schwermetallionen und organische Schadstoffe ein hohes Risiko für aquatische Lebensräume und letztendlich auch den Menschen dar. Durch unzureichende Entfernung tragen sie außerdem zum Verlust nicht-erneuerbarer Rohstoffe für industrielle Kreisläufe bei. Durch eine meist geringe Effektkonzentration und potentielle Wechselwirkungen mit diversen Lebewesen ist die Entfernung vieler Verunreinigungen extrem wichtig, um bestehende Ökosysteme nicht weiter zu verändern. Adsorption stellt eine energieeffiziente Methode zur Entfernung dieser Schadstoffe durch hierfür geeignete Adsorbentien dar. Hochgradig vernetzte Harzpolymere wie Poly(melamin-co-formaldehyd) (PMF) stellen mit ihrer sehr hohen chemischen Beständigkeit, einer hohen Zahl funktioneller Gruppen und einfachen Herstellbarkeit einen vielversprechenden Ausgangspunkt für Adsorbentien dar. Diese Dissertation beschreibt die kolloidale, wässrige Synthese nanoporöser Harzpartikel (z. B. PMF) durch eine Templatierung mit SiO2 Nanopartikeln (SiO2 NPs), welche anschließend zur Adsorption von Wasserschadstoffen eingesetzt werden. Ein übergeordnetes Ziel dieser Arbeit besteht aus der Aufklärung des Mechanismus zur Partikel- und Porenbildung durch systematische Variation verschiedener Syntheseparameter. Mittels Elektronenmikroskopie, N2-Sorption und Partikelgrößenmessung wird die Morphologie, Größe und Porenstruktur der Partikel analysiert. Umfassende Untersuchungen ermöglichen somit, den Einfluss der einzelnen getesteten Syntheseparameter auf diese Eigenschaften zu bestimmen. Ein sehr wichtiges Ziel, besonders für eine zukünftige großtechnische Anwendbarkeit, ist dabei die kolloidale Herstellung uniformer Partikel, welche sowohl eine hohe geordnete Porosität als auch Partikeldurchmesser im Bereich einiger Mikrometer aufweisen. Dies ermöglicht einen Einsatz als durchströmbaren Festbett-Adsorber. Dieses Ziel ist eng mit der mechanistischen Aufklärung der Poren- und Partikelbildung in der Synthese verknüpft. Die hergestellten nanoporösen PMF-Partikel wurden nach ihrer Charakterisierung für verschiedene Adsorptionsanwendungen getestet. Um ein umfassendes Bild über die Einsetzbarkeit von PMF-Partikeln zu erhalten, sollen jeweils Versuche mit Oxyanionen, mit Schwermetallionen und mit Pharmazeutika als Vertreter organischer Schadstoffe durchgeführt werden. Bei diesen Versuchen steht zum einen die Untersuchung der Adsorptionsleistung und des Adsorptionsmechanismus des jeweiligen Schadstoffes an PMF im Vordergrund. Zum anderen wird durch die Verwendung verschiedener Partikel, bei welchen ein einzelner Syntheseparameter variiert wurde, der Einfluss der veränderten Porosität auf den Adsorptionsmechanismus untersucht. Sulfat- und Phosphationen wurden in der Klasse der Oxyanionen untersucht. Für beide Ionen wurden extrem hohe Abtrennraten nachgewiesen, welche bisherige kommerziell erhältliche Materialien signifikant übertraf. In Versuchen hinsichtlich einer potentiellen selektiven Adsorption und somit Trennung beider Spezies, zeigten die PMF/SiO2-Hybridpartikel, bei welchen das Templat noch nicht entfernt wurde, eine selektive Sulfatadsorption. Die Immobilisierung von Schwermetallionen wurde mit besonderem Fokus auf die gleichzeitig auftretende Abtrennung der dafür verwendeten Cu2+-Ionen und jeweiliger Anionen analysiert. Durch Untersuchungen des Adsorbens nach den Adsorptionsversuchen mittels Elektronenmikroskopie, Röntgenstreuung und Elektronenspinresonanz-Spektroskopie wurde der bisher unzureichend analysierte Adsorptionsmechanismus aufgeklärt. Hierbei wurden Adsorption und oberflächeninduzierte Fällung als separate Teilprozesse identifiziert, welche beide jeweils für die Abscheidung von sowohl Metall- als auch Anionen aus der Lösung verantwortlich sind. Bei Adsorptionsversuchen mit den einwertigen Ionen Nitrat und Chlorid wurde ein zweistufiger Prozess identifiziert, welcher erstmals über eine neue Adsorptionsisotherme mathematisch beschrieben wurde. Im Bereich organischer Wasserschadstoffe wird die Abtrennung des Pharmazeutikums Diclofenac getestet. Insbesondere die Adsorption von Pharmazeutika stellt aufgrund von deren geringen Effektkonzentration und Allgegenwärtigkeit in Oberflächen- und Leitungswässern ein dringliches Thema dar. Die Pharmazeutika-Abtrennung mittels PMF wurde trotz seiner vielversprechenden Eigenschaften weltweit bisher kaum untersucht. Im Rahmen dieser Versuche wurden Partikel getestet, welche mit unterschiedlich großen und unterschiedlich stabilisierten SiO2 NPs templatiert wurden. Dadurch entstanden Porensysteme, die besonders in derer Zugänglichkeit ihres Porensystems und in dem Durchmesser der Verbindungskanäle zwischen den Hauptkavitäten voneinander variierten. Diese Eigenschaften wirkten sich signifikant auf die Adsorptionskapazität und die Abtrennraten im niedrigen Konzentrationsbereich aus. Ein abschließendes Ziel ist die Synthese eines Harznetzwerkes, welches statt Melamin auf einem ebenso hochfunktionellen, triazinbasierten Monomer basiert. Das Monomer 2,4,6-Tris(2,4,6-trihydroxyphenyl)-1,3,5-triazin (3PT) besitzt jeweils neun Hydroxylgruppen, wodurch ein darauf basierendes Polymer stark veränderte Adsorptionseigenschaften gegenüber PMF aufweisen soll. Mit diesem Monomer wurde in einer analog zu PMF durchgeführten wässrigen Polymerisation ein bisher unbekanntes Polymernetzwerk hergestellt, welches als P(3PT-F) bezeichnet wurde. Hierbei wurde auf Templatierung verzichtet, da das neu hergestellte Material bereits intrinsische Nanoporosität durch die Größe des verwendeten 3PT-Monomers aufwies. In anschließenden Adsorptionsversuchen wurden sehr hohe Abtrennraten für die toxischen Metallion Pb2+, Cd2+ und Ni2+ nachgewiesen. In realistischen Ausgangskonzentrationen wurde die Kontamination mit diesen Ionen jeweils auf Trinkwasserqualität reduziert. P(3PT-F) zeigte außerdem eine sehr selektive Abtrennung von Pb2+ gegenüber den häufig vorkommenden Ionen Ca2+, Mg2+, K+ und Fe2+. Als grundlegender Beweis konnte eine Wiederverwendbarkeit durch die vollständige Desorption mit verdünnter HCl gezeigt werden und eine anschließende erneute Adsorption ohne signifikante Verringerung der Kapazität. Insgesamt wurde ausgehend von der grundlegenden Untersuchung der PMF-Partikelsynthese erst ein generelleres Verständnis der wässrigen Dispersionspolymerisation hydrophober Harze abgeleitet und die Templatierung mit hydrophilen SiO2 NPs implementiert. Mithilfe des Verständnisses der Partikelwachstumsprozesse und der Wechselwirkungen, welche für die Templatierung verantwortlich sind, konnten die Eigenschaften der entstehenden Partikel gesteuert werden. Im Rahmen der Adsorptionsuntersuchungen konnte anschließend der Einfluss insbesondere der veränderten Porosität auf die Abtrennleistung untersucht werden. Außerdem konnte analysiert werden, welche Wechselwirkungen PMF mit den jeweiligen Schadstoffarten eingeht. Durch den Austausch des Monomers Melamin gegen das hydroxylhaltiges Monomer 3PT konnte ein neuartiges Harzpolymer hergestellt werden. Dieses kann mit seiner veränderten Porosität und Reaktivität nun als neuer Ausgangspunkt für Adsorptionsexperimente mit stark veränderter Adsorptionsleistung z. B. gegenüber Schwermetallionen dienen.:Abstract 1 Kurzfassung 5 List of Publications 9 First-Author Publications 9 Co-Author Publications 10 Patent 12 Conference Proceedings 12 Oral Presentations 12 Poster 12 List of Figures 13 Mesoporous Poly(Melamine-co-Formaldehyde) Particles for Efficient and Selective Phosphate and Sulfate Removal: 14 Tuning the Pore Structure of Templated Mesoporous Poly(melamine-co-formaldehyde) Particles toward Diclofenac Removal: 15 Adsorption vs. Surface Precipitation of Cu²+ onto Porous Poly(melamine-co-formaldehyde) Particles: 16 SiO2 Nanospheres as Surfactant and Template in Aqueous Dispersion Polymerizations Yielding Nanoporous Resin Particles: 18 Waterborne Phenolic, Triazine-Based Porous Polymer Particles for the Removal of Nickel, Cadmium, and Lead Ions: 19 List of Tables 21 Mesoporous Poly(Melamine-co-Formaldehyde) Particles for Efficient and Selective Phosphate and Sulfate Removal: 21 Tuning the Pore Structure of Templated Mesoporous Poly(melamine-co-formaldehyde) Particles toward Diclofenac Removal: 21 Adsorption vs. Surface Precipitation of Cu²+ onto Porous Poly(melamine-co-formaldehyde) Particles: 22 SiO2 Nanospheres as Surfactant and Template in Aqueous Dispersion Polymerizations Yielding Nanoporous Resin Particles: 22 Waterborne Phenolic, Triazine-Based Porous Polymer Particles for the Removal of Nickel, Cadmium, and Lead Ions: 23 Abbreviations 25 Symbols 26 1. Introduction 1 2. Objectives and Experimental Design 5 3. Scientific Background 11 3.1. Poly(melamine-co-formaldehyde) 11 3.1.1. Polymerization Mechanism 11 3.1.2. Synthesis Strategies for the Preparation of Porous PMF Particles. 13 3.1.3. Fields of Application of PMF 13 3.2. Adsorption 15 3.2.1. Adsorption Isotherms and Mathematical Modeling 16 3.3. Surface Precipitation 20 4. Fundamentals of Instrumental Analytics 23 4.1. Gas Sorption Measurements 23 4.1.1. Determination of

    Advances and Applications of DSmT for Information Fusion. Collected Works, Volume 5

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    This fifth volume on Advances and Applications of DSmT for Information Fusion collects theoretical and applied contributions of researchers working in different fields of applications and in mathematics, and is available in open-access. The collected contributions of this volume have either been published or presented after disseminating the fourth volume in 2015 in international conferences, seminars, workshops and journals, or they are new. The contributions of each part of this volume are chronologically ordered. First Part of this book presents some theoretical advances on DSmT, dealing mainly with modified Proportional Conflict Redistribution Rules (PCR) of combination with degree of intersection, coarsening techniques, interval calculus for PCR thanks to set inversion via interval analysis (SIVIA), rough set classifiers, canonical decomposition of dichotomous belief functions, fast PCR fusion, fast inter-criteria analysis with PCR, and improved PCR5 and PCR6 rules preserving the (quasi-)neutrality of (quasi-)vacuous belief assignment in the fusion of sources of evidence with their Matlab codes. Because more applications of DSmT have emerged in the past years since the apparition of the fourth book of DSmT in 2015, the second part of this volume is about selected applications of DSmT mainly in building change detection, object recognition, quality of data association in tracking, perception in robotics, risk assessment for torrent protection and multi-criteria decision-making, multi-modal image fusion, coarsening techniques, recommender system, levee characterization and assessment, human heading perception, trust assessment, robotics, biometrics, failure detection, GPS systems, inter-criteria analysis, group decision, human activity recognition, storm prediction, data association for autonomous vehicles, identification of maritime vessels, fusion of support vector machines (SVM), Silx-Furtif RUST code library for information fusion including PCR rules, and network for ship classification. Finally, the third part presents interesting contributions related to belief functions in general published or presented along the years since 2015. These contributions are related with decision-making under uncertainty, belief approximations, probability transformations, new distances between belief functions, non-classical multi-criteria decision-making problems with belief functions, generalization of Bayes theorem, image processing, data association, entropy and cross-entropy measures, fuzzy evidence numbers, negator of belief mass, human activity recognition, information fusion for breast cancer therapy, imbalanced data classification, and hybrid techniques mixing deep learning with belief functions as well

    Systemic Circular Economy Solutions for Fiber Reinforced Composites

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    This open access book provides an overview of the work undertaken within the FiberEUse project, which developed solutions enhancing the profitability of composite recycling and reuse in value-added products, with a cross-sectorial approach. Glass and carbon fiber reinforced polymers, or composites, are increasingly used as structural materials in many manufacturing sectors like transport, constructions and energy due to their better lightweight and corrosion resistance compared to metals. However, composite recycling is still a challenge since no significant added value in the recycling and reprocessing of composites is demonstrated. FiberEUse developed innovative solutions and business models towards sustainable Circular Economy solutions for post-use composite-made products. Three strategies are presented, namely mechanical recycling of short fibers, thermal recycling of long fibers and modular car parts design for sustainable disassembly and remanufacturing. The validation of the FiberEUse approach within eight industrial demonstrators shows the potentials towards new Circular Economy value-chains for composite materials

    Pushing Light-Sheet Microscopy to Greater Depths

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    Light-sheet fluorescence microscopy (LSFM) has established itself as an irreplaceable imaging technique in developmental biology over the past two decades. With its emergence, the extended recording of in toto datasets of developing organisms across scales became possible. Remarkably, LSFM opened the door to new spatio-temporal domains in biology, offering cellular resolution on the one hand, and temporal resolution on the order of seconds on the other hand. As in any fluorescence microscopy technique, LSFM is also affected by image degradation at greater tissue depths. Thus far, this has been addressed by the suppression of scattered light, use of fluorophores emitting in the far red spectrum, multi-view detection and fusion, adaptive optics, as well as different illumination schemes. In this work, I investigate for the first time in vivo optical aberration reduction via refractive index matching in LSFM. Examples are shown on common model organisms as Arabidopsis thalina, Oryzias latipes, Mus musculus, as well as Drosophila. Additionally, I present a novel open-top light-sheet microscope, tailored for high-throughput imaging of mammalian samples, such as early stage mouse embryos. It is based on a three objective geometry, encompassing two opposing detection objective lenses with high light collection efficiency, and an invertedly mounted illumination lens. It bridges the spatial scale between samples by employing an extendible light-sheet illumination via a tunable acoustic gradient index lens. Both parts of this work improve the image quality across the 3D volume of specimens, paving the way for more quantitative recordings at greater tissue depths

    Metaverse. Old urban issues in new virtual cities

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    Recent years have seen the arise of some early attempts to build virtual cities, utopias or affective dystopias in an embodied Internet, which in some respects appear to be the ultimate expression of the neoliberal city paradigma (even if virtual). Although there is an extensive disciplinary literature on the relationship between planning and virtual or augmented reality linked mainly to the gaming industry, this often avoids design and value issues. The observation of some of these early experiences - Decentraland, Minecraft, Liberland Metaverse, to name a few - poses important questions and problems that are gradually becoming inescapable for designers and urban planners, and allows us to make some partial considerations on the risks and potentialities of these early virtual cities

    LIPIcs, Volume 261, ICALP 2023, Complete Volume

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    LIPIcs, Volume 261, ICALP 2023, Complete Volum

    Transport Properties and Magnetoresistance of Cluster-Assembled Fe-Ge and Fe-Ag Nanocomposites

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    Granular nanocomposites are composite materials in which grain-like particles with dimensions on the order of nanometers form one of the phases. These nanoparticles are embedded in a second phase, the matrix. Such granular nanocomposites constitute a very promising class of materials with great potential for novel and tailorable properties, making granular nanocomposites especially interesting for scientific endeavor. In the simplest case, granular nanocomposites are synthesized via co-deposition of two immiscible chemical elements. In this approach, nanoparticles grow via incorporation of diffusing atoms of one of the elements forming the prototype material; the remaining atoms of the other element constitute the matrix. This phase segregation process may be assisted by thermal annealing. Another approach used to form granular nanocomposite prototype materials is to ion-implant nanoparticle-type atoms into already grown films or wafer surfaces. However, since these two approaches utilize the immiscibility of the combined materials, they can be applied to such immiscible material systems only. Furthermore, the range of achievable elemental compositions and particle sizes is limited. An interesting alternative strategy to synthesize granular nanocomposites is to deposit the matrix material simultaneously with preformed, spherical nanoparticles. In this approach, the nanoparticles are embedded into the matrix in a direct fashion. The preformed, spherical nanoparticles are called clusters, correspondingly, the created nanomaterials are called cluster-assembled nanocomposites. The great advantage of this special co-deposition approach is that it allows for the creation of nanocomposites out of elements that are at least partially miscible or that can form crystallographic mixed phases—that is, for the creation of so-called nonequilibrium compositions. Embedding the nanoparticles as preformed constituents instead of letting them segregate during the deposition process also increases the degree of control over the deposition process. An ultimate degree of control over the composition is achieved when the clusters are size-selected prior to deposition. This is the strategy pursued in the present thesis. Here, a cluster ion beam deposition system that features a narrow cluster size distribution of ±10% is used to synthesize films of cluster-assembled nanocomposites. Two different nanocomposites are prepared and examined: nanocomposites made of Fe-clusters embedded in Ge-matrices and nanocomposites of Fe-clusters embedded in Ag-matrices. The created Fe-clusters are only a few nanometers in size and, therefore, of superparamagnetic kind. The study of the physical properties of the prepared nanocomposites as a function of cluster size and cluster concentration, in particular, of their transport and magnetoresistive properties, is the central aim of this thesis. First, the Fe-Ge nanocomposites are examined. In this course, also the process of sample preparation and the various performed measurements are discussed. Embedding magnetic Fe nanoparticles into a semiconductor aims for a synthesis of the magnetic and the semiconducting properties, that is, for the creation of so-called magnetic semiconductors. Magnetic semiconductors define a class of materials whose properties can be controlled by means of a magnetic field in addition to—or even instead of—an electric field. For this reason, magnetic semiconductors represent an essential component for the emerging field of spintronics. Two series of Fe-Ge nanocomposites are prepared: one with clusters consisting of 500 ± 50 Fe atoms and one with clusters consisting of 1000 ± 100 Fe atoms. In the course of the analysis, Ge is found to grow in an amorphous structure under the conditions of the co-deposition experiments. A co-deposition sample layout that consists of a co-deposition mask and a complementing sample chip layout is developed. The deposited nanocomposite samples are studied by means of resistance and magnetoresistance measurements in a cryostat, by means of scanning electron microscopy including energy-dispersive X-ray spectroscopy, and by means of SQUID magnetometry. Besides tunneling magnetoresistance, which is negative, of saturating kind, and observed with a magnitude on the order of 1% here, at least one other effect not saturating within the examined magnetic field range of |µ0 H| ≤ 6 T is observed. Several effects that may explain the observed non-saturating behavior are discussed, however, the origin remains unsolved. Furthermore, the resistivity of the Fe-Ge nanocomposites as well as the tunneling magnetoresistance are each found to be a function of the average distance between the surfaces of neighboring clusters rather than the average distance between their centers of mass. Finally, some of the Fe-Ge nanocomposite samples are thermally annealed in vacuum, under the presence of hydrogen gas, and at two different temperatures in various steps. Thermal annealing alters the structure of the as-deposited nanocomposites, which is reflected by changes in the measured physical properties. These changes are identified and discussed. Secondly, the Fe-Ag nanocomposites are examined. In comparison to the Fe-Ge system, the Fe-Ag system is represented in the literature rather well. In particular, it is well-known that the giant magnetoresistance effect can occur in layered as well as in granular Fe-Ag structures. Here, the aim is to confirm that the applied methods give results comparable to those found in the literature and to perhaps even improve upon existing data. Again, two series of nanocomposite samples with clusters consisting of 500 and 1000 Fe atoms, respectively, are fabricated. In addition, a third series of Fe-Ag nanocomposite samples with clusters consisting of 1500 ± 150 Fe atoms is prepared. Giant magnetoresistance of maximum −6% is observed. The giant magnetoresistance effect increases in magnitude with decreasing size of the embedded clusters. Furthermore, an optimum composition of clusters and matrix material for a maximum magnitude of the giant magnetoresistance effect seems to exist. However, no clear dependence of the measured properties on neither the Fe concentration nor the average distance between the surfaces of neighboring clusters is observed. Besides the examination of Fe-Ge and Fe-Ag nanocomposites, a setup that combines laser ablation and inert gas condensation is designed and assembled. In contrast to other techniques, laser ablation features a large fraction of uncharged output particles. Further, laser ablation also allows for the creation of nanoparticles made of electrically insulating materials. Accordingly, the original application considered for the setup lies in the field of matter-wave diffraction experiments. In principle, the setup may be used for the deposition of cluster-assembled materials as well. However, it has never been used for experiments in any of these fields. Nevertheless, the present state of the setup as well as its principle of operation are reviewed. The review is completed with a brief analysis of a test sample of collected Ag clusters prepared with the setup
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