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Dissertations / Theses on the topic 'Hydrogele'

Author: Grafiati

Published: 4 June 2021

Last updated: 19 February 2022

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1

Gramm, Stefan. "Thermisch schaltbare Hydrogele - Synthese - Charakterisierung - Anwendung." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2006. http://nbn-resolving.de/urn:nbn:de:swb:14-1163522282581-78351.

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Gegenstand dieser Arbeit war die Synthese von thermisch schaltbaren Kammcopolymeren auf Basis von N-(Isopropylacrylamid) (NiPAAm) und Polyethylenglykolmakromonomeren (PEGMA). Die intensive Charakterisierung der aus diesen Copolymeren hergestellten Schichten und deren Anwendung als Zellkultursubstrate war ein weiteres Forschungsziel dieser Arbeit. Die mit Hilfe der neuartigen Schichten erhaltenen Zellkultursubstrate wurden anhand verschiedener adhärenter Zelllinien erfolgreich getestet. Alle getesten Zelltypen (Mausfibroblasten, humane Endothelzellen der Nabelschnurvene und humane korneale Endothelzellen) proliferierten auf den angebotenen Zellkultursubstraten bei 37°C und konnten durch senken der Temperatur geerntet werden.

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2

Rohn, Mathias. "Strukturcharakterisierung photochemisch vernetzter tetra-PEG Hydrogele mit unterschiedlichem Aufbau." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-229602.

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Die Funktionalisierung von tetra-PEG Makromolekülen mit fotoreaktiven Gruppen und die anschließende Umsetzung zu Hydrogelen durch fotochemische Vernetzung werden beschrieben. Die Funktionalisierung der Makromoleküle wird mittels UV-Vis- und NMR-Spektroskopie nachgewiesen, während der Verlauf der Vernetzung über die dynamische Lichtstreuung und IR-Spektroskopie betrachtet wird. Die hergestellten Hydrogele werden hinsichtlich des Sol-Anteils und der Quelleigenschaften untersucht. Über den Umsatz wird die Konzentration der Netzketten theoretisch berechnet. Einen weiteren Schwerpunkt bildet die Charakterisierung der Hydrogele hinsichtlich der mechanischen Eigenschaften. Über den Speichermodul wird die Konzentration der Netzketten experimentell bestimmt. Mittels dynamischer Lichtstreuung werden die kooperativen Diffusionskoeffizienten und Maschenweiten der Hydrogele bestimmt.

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3

Schädel, Nicole [Verfasser]. "Synthese modularer Vernetzer für maßgeschneiderte Hydrogele / Nicole Schädel." München : Verlag Dr. Hut, 2019. http://d-nb.info/1196415676/34.

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4

Fänger, Christian. "Schaltbare polymere Hydrogele für die reversible Immobilisierung von Enzymen." [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=980461995.

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5

Mateescu, Markus [Verfasser]. "Pyridin-basierte Acryl-Vernetzer für bioinspirierte Hydrogele / Markus Mateescu." München : Verlag Dr. Hut, 2014. http://d-nb.info/105237560X/34.

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6

Pfeifer, Christoph [Verfasser], and M. [Akademischer Betreuer] Wilhelm. "Separation Media Based on Defined Hydrogel Systems = Hydrogele als Separationsmedien auf Basis definierter Porengrößen / Christoph Pfeifer ; Betreuer: M. Wilhelm." Karlsruhe : KIT-Bibliothek, 2020. http://d-nb.info/1216949476/34.

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7

Leiendecker, Mai-Thi [Verfasser], and Alexander [Akademischer Betreuer] Böker. "Physikalische Hydrogele auf Polyurethan-Basis / Mai-Thi Leiendecker ; Betreuer: Alexander Böker." Potsdam : Universität Potsdam, 2017. http://d-nb.info/1218401745/34.

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8

Baumann, Bernhard Harry [Verfasser]. "Synthese und Charakterisierung hybrider Hydrogele für die Geweberekonstruktion / Bernhard Harry Baumann." Ulm : Universität Ulm, 2018. http://d-nb.info/1166757315/34.

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9

Nguyen-Kim, Mai Thi [Verfasser], and Alexander [Akademischer Betreuer] Böker. "Physikalische Hydrogele auf Polyurethan-Basis / Mai-Thi Leiendecker ; Betreuer: Alexander Böker." Potsdam : Universität Potsdam, 2017. http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-103917.

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10

Wenz, Annika [Verfasser], and Günter [Akademischer Betreuer] Tovar. "Mikroextrudierbare Hydrogele für den Aufbau vaskularisierter Knochengewebeäquivalente / Annika Wenz ; Betreuer: Günter Tovar." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2018. http://d-nb.info/1163604062/34.

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11

Chen, Zimei [Verfasser]. "Einfluss organischer Hydrogele und Polymere auf die Synthese nanostrukturierter Metalloxide / Zimei Chen." Paderborn : Universitätsbibliothek, 2021. http://d-nb.info/1228431841/34.

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12

Kretschmann, Oliver. "Assoziative Hydrogele und thermosensitive Polymer-Einschlussverbindungen auf Basis von adamantylhaltigen Polymeren und Cyclodextrinen." [S.l.] : [s.n.], 2007. http://deposit.ddb.de/cgi-bin/dokserv?idn=983203989.

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13

Harling, Steffen [Verfasser], and Henning [Akademischer Betreuer] Menzel. "Hydrogele als Drug Delivery Systeme basierend auf Hydroxyethylstärke / Steffen Harling ; Betreuer: Henning Menzel." Braunschweig : Technische Universität Braunschweig, 2010. http://d-nb.info/1175827649/34.

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14

Walter, Sarah Verena [Verfasser], and Mathias [Akademischer Betreuer] Ulbricht. "Glucose-responsive Hydrogele für Drucksensor-basierte Anwendungen / Sarah Verena Walter ; Betreuer: Mathias Ulbricht." Duisburg, 2021. http://d-nb.info/1228270422/34.

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15

Niedl, Robert Raimund [Verfasser], and Carsten [Akademischer Betreuer] Beta. "Nichtlineare Kinetik und responsive Hydrogele für papierbasierte Schnelltestanwendungen / Robert Raimund Niedl ; Betreuer: Carsten Beta." Potsdam : Universität Potsdam, 2015. http://d-nb.info/1218495499/34.

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16

Schwoerer, Ariane Dorothea Annette [Verfasser], and Henning [Akademischer Betreuer] Menzel. "Hydroxyethylstärke-Hydroxyethylmethacrylat-Hydrogele als Freisetzungssystem für Proteine / Ariane Dorothea Annette Schwoerer ; Betreuer: Henning Menzel." Braunschweig : Technische Universität Braunschweig, 2010. http://d-nb.info/1175828963/34.

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17

Niedl, Robert [Verfasser], and Carsten [Akademischer Betreuer] Beta. "Nichtlineare Kinetik und responsive Hydrogele für papierbasierte Schnelltestanwendungen / Robert Raimund Niedl ; Betreuer: Carsten Beta." Potsdam : Universität Potsdam, 2015. http://d-nb.info/1218495499/34.

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18

Weber, Heather. "A starPEG-heparin hydrogel model of renal tubulogenesis." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-224094.

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Currently, the only treatment for end stage renal disease is dialysis or kidney transplantation. These methods contain obvious limitations such as the palliative nature of dialysis treatment and the lack of available organs for transplantation. As a result, there is a dire unmet need for alternative options. Regenerative therapies that focus on stimulating the regrowth of injured tissue can be a promising alternative. A critical step in the development of such therapeutic remedies is obtaining robust models that mimic the complex nature of the human kidney. The proximal tubules are a particular region of interest due to their important role in reabsorption and secretion of the glomerular filtrate and the blood, making them particularly susceptible to nephrotoxicity and renal pathologies. For this reason, the goal of this thesis was to engineer a 3D model of human proximal tubulogenesis that would allow for both developmental and regenerative studies. The ideal assay would mimic the human 3D structure and function of proximal tubules in a tunable, robust matrix that can be easily analyzed in throughput screenings for regenerative medicine and toxicity applications. In this thesis, we show the development, characterization, and application of an in vitro human renal tubulogenesis model using a modular and tunable biohybrid starPEG-heparin hydrogel platform. A range of hydrogel mechanics and compositions were systematically tested to determine the optimal conditions for renal tubulogenesis. The results revealed that only soft hydrogels based on heparin and matrix metalloproteinase (MMP) enzymatically cleavable crosslinkers led to the generation of polarized tubule structures. The generated tubules display polarization markers, extracellular matrix components, and organic anion transport functions which mimic the human renal proximal tubule. To the best of our knowledge, this is the first system where human renal tubulogenesis can be monitored ex vivo from single cells to physiologically sized tubule structures in a 3D tunable matrix. Moreover, it was found that heparin played a role in the polarization of proximal tubule cells in the hydrogel culture. The established starPEG-MMP-heparin based hydrogel model was then tested for its application as a renal tubulogenesis model by the addition of pro and anti-tubulogenic factors. It was found that the addition of growth factors and MMP inhibitors could promote and inhibit tubulogenesis, respectively. This model can be used to modulate tubulogenesis by adjusting the mechanical properties of the hydrogel, growth factor signaling, and the presence of insoluble cues (such as adhesion peptides), potentially providing new insights for regenerative therapy. To examine if the established hydrogel-based renal tubulogenesis model could be applied as a drug toxicity platform, the nephrotoxic, chemotherapeutic drug, cisplatin was incubated with the renal tubule model. The tubular structures showed a dose-dependent drug response resembling the human clinical renal pathology. The injured tubular structures also expressed the early in vivo proximal tubule injury biomarker, kidney injury molecule-1 (KIM-1). In conclusion, a hydrogel-based renal tubulogenesis model was successfully developed, characterized, and applied as a nephrotoxicity assay. Our findings suggest that the established hydrogel-based model can additionally be used for personalized medicine, where a patient’s predisposition to drug-induced renal injury or specific renal regenerative medicine treatments could be examined. This platform provides a novel approach to study human nephrotoxicity and renal regenerative medicine ex vivo, limiting the need for animal models, and potentially paving the way for more reliable preclinical trials.

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19

Adelsberger, Joseph G. [Verfasser], Christine M. [Akademischer Betreuer] Papadakis, and PETER [Akademischer Betreuer] BOENI. "Struktur und Kinetik thermoresponsiver Hydrogele / Joseph G. Adelsberger. Gutachter: Peter Böni. Betreuer: Christine M. Papadakis." München : Universitätsbibliothek der TU München, 2012. http://d-nb.info/1019589736/34.

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20

Dibbert, Nick [Verfasser]. "Darstellung neuer Hydrogele zur Anwendung im tissue engineering : Studien zur Darstellung neuer Kinaseinhibitoren / Nick Dibbert." Hannover : Technische Informationsbibliothek (TIB), 2017. http://d-nb.info/1128664887/34.

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21

Kupka, Julia [Verfasser]. "Studien zur Synthese von aromatischen Acrylamid, Methacrylamid und Maleinimid Vernetzern für bioinspirierte Hydrogele / Julia Kupka." München : Verlag Dr. Hut, 2017. http://d-nb.info/1226434517/34.

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22

Kupka, Julia Stefanie [Verfasser]. "Studien zur Synthese von aromatischen Acrylamid, Methacrylamid und Maleinimid Vernetzern für bioinspirierte Hydrogele / Julia Kupka." München : Verlag Dr. Hut, 2017. http://d-nb.info/1226434517/34.

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23

Pareek, Pradeep. "Photo-crosslinked Surface Attached Thin Hydrogel Layers." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2005. http://nbn-resolving.de/urn:nbn:de:swb:14-1115623310082-44480.

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Stimuli sensitive polymers and hydrogels respond with large property changes to small physical and chemical stimuli (e.g. temperature, pH, ionic strength). The bulk behavior of these polymers is widely studied and they show an isotropic swelling. However, thin hydrogel layers of polymers on a substrate show a swelling behavior, which is constrained in some way. Therefore, size, confinement, patternability, response time and transition temperature of thin hydrogel layers are the most important parameters in technological applications and this study focuses on the investigation of these above-mentioned parameters. The aim of this study involves synthesis, characterization and application of thin photo-crosslinked hydrogel layers. Dimethylmaleimide (DMI) moiety was incorporated in the polymers chains and was used to introduce photo-crosslinking by [2+2] cyclodimerization reaction in the presence of UV irradiation. The following photo-crosslinkers based on DMI group were synthesized ? - Acrylate photo-crosslinker (DMIAm) - Acrylamide photo-crosslinker (DMIAAm) - Polyol photo-crosslinker (DMIPA, DMIPACl) The conventional free radical polymerization of above listed photo-crosslinker with its respective monomer resulted in formation of photo-crosslinkable polymers of (a) HEMA, (b) DMAAm, (c) NIPAAm/DMAAm, (d) NIPAAm/Cyclam. The properties of these polymers were investigated by NMR, UV-VIS spectroscopy, GPC and SPR. Thin hydrogel layers were prepared by spin coating on gold-coated LaSFN9 glass. The covalent attachment to the surface was achieved through an adhesion promoter. Swelling behavior of the thin polymer layers was thoroughly investigated by Surface Plasmon Resonance (SPR) Spectroscopy and Optical Waveguide Spectroscopy (OWS). SPR and OWS gave a wide range of information regarding the film thickness, swelling ratio, refractive index, and volume degree of swelling of the thin hydrogel layer. For hydrophilic photo-crosslinked hydrogel layers of HEMA and DMAAm, it was observed that the volume degree of swelling was independent of temperature changes but was dependent on the photo-crosslinker mol-% in the polymer. These surface attached thin hydrogel layer exhibited an anisotropic swelling. For NIPAAm photo-crosslinked hydrogel layers with DMAAm as a hydrophilic monomer, it was observed that both transition temperature (Tc) and volume degree of swelling increases with increase in the mol-% of DMAAm. To study the effect of film thickness on Tc and volume degree of swelling, hydrogels with wide range of film thickness were prepared and investigated by SPR. These results provided vital information on the swelling behavior of surface attached hydrogel layer and showed the versatility of SPR instrument for studying thin hydrogel layers. Later part of project involved synthesis of multilayer hydrogel assembly involving a thermoresponsive polymer and a hydrophilic polymer. The combination of two layers with photo-crosslinkable DMAAm polymer as base layer and photo-crosslinkable NIPAAm polymer as top layer formulate a multilayer assembly where, the base layer only swells in response to temperature and the top layer shows temperature dependent swelling. Photo-crosslinked hydrogel layers of NIPAAm, DMAAm and HEMA shows a high-resolution patterns when irradiated by UV light through a chromium mask. At last this study focused on an important application of these hydrogel layers for cell attachment processes. Cell growth, proliferation and spreading shows a biocompatible nature of these hydrogel surfaces. Such thermoresponsive photo-crosslinkable multilayer structure forms bases for future projects involving their use in actuator material and cell-attachment processes.

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24

Jorsch, Carola. "Implantierbare Sensoren auf Hydrogelbasis." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-231935.

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In der vorliegenden Arbeit wurde eine neue Klasse von implantierbaren biochemischen Sensoren bezüglich ihrer Sensitivität im physiologisch relevanten pH- (pH 7,4) sowie Glukose-Konzentrationsbereich (2 - 20 mM) entwickelt und untersucht. Die Glukose-sensitiven Hydrogele basieren auf der Bindung von 5-fach-Zuckern an Boronsäuregruppen, die in einem Acrylamid-basierten Hydrogel mit N,N′-Methylenbisacrylamid (BIS) als Vernetzter (AAm/APB/BIS, 80/20/0,75 mol%) verankert sind. Weiterhin konnten pH-sensitive Hydrogele auf Basis von 2-(Dimethylamino)ethyl Methacrylate (DMAEMA), Hydroxypropyl-methacrylat (HPMA) sowie Tetraethyleneglycol dimethacrylate (TEGDMA) als Vernetzter in unterschiedlichen Zusammensetzungen und Geometrien untersucht werden. Die verwendeten Hydrogele wurden hinsichtlich der Diffusionsprozesse sowie ihrer Quellkinetik charakterisiert, um deren Sensitivität, Selektivität, Reproduzierbarkeit und Ansprechzeit gegenüber den physiologischen Parametern (pH, pCO2, Glukose) zu verbessern. Die aufgebauten pCO2-Sensoren zeigten vielversprechende Ansprechzeiten von wenigen Minuten. Die Glukose und pH-Sensoren wiesen im physiologischen Medium (PBS) deutlich höhere Ansprechzeiten von mehreren Stunden auf. Die Kombination von piezoresistiven Drucksensoren mit Stimuli-sensitiven Hydrogelen bietet nicht nur eine große Vielfalt bezüglich der zu detektierenden Analyten, sondern ermöglicht auch miniaturisierte und implantierbare Sensoren für die kontinuierliche Erfassung von physiologischen Parametern. So war die Verkapselung zum Schutz und zugleich zur Gewährleistung der Biokompatibilität und ohne Beeinträchtigung der Funktionalität und Flexibilität der elektronischen Bauteile das Ziel. Dazu wurden die Sensoren mit dem Polymer Parylene C eingehaust, dass zusätzlich eine Polyethylenglykolschicht enthielt. Hierfür wurden Blockcopolymere mittels Ringöffnungspolymerisation synthetisiert, die Polyaminosäuren als Linkermoleküle und PEG zur gezielten Funktionalisierung enthalten. Nach kovalenter Anbindung an die inerte Parylene C-Oberfläche zeigten sich deutlich veränderte Oberflächeneigenschaften und eine verbesserte Zellkompatibilität und Hämokompatibilität. Zudem wurde der sogenannte Tarnkappeneffekt von PEG-Ketten, die sich in der Schicht nach außen ausrichten, festgestellt. Damit wurde Adsorption von Proteinen (Fibronektin, Fibrinogen), die in Entzündungsreaktionen, der Zelladhäsion sowie der Blutgerinnung maßgebend sind, deutlich verringert
In this work a new class of implantable biochemical sensors with a high sensitivity at physiological pH (pH 7,4) and glucose (2 – 20 mM) ranges were developed and tested. The glucose sensitive hydrogel was made of acrylamide and N,N′-methylene-bis(acrylamide) as a crosslinker (AAm/APB/BIS, 80/20/0,75 mol%). The swelling mechanism was based on the reversible interaction of sugar molecules and the boronic acid groups in the hydrogel. Also a pH sensitive hydrogel made of 2-(dimethylamino) ethyl methacrylate (DMAEMA), hydroxypropyl-methacrylat (HPMA) and the crosslinker tetraethylene glycol dimethacrylate (TEGDMA) with different molar ratios and geometries was characterized. The swelling kinetics as well as the diffusion processes of different hydrogels were studied to advance sensitivity, selectivity, reproducibility and response time with respect to physiological parameters (pH, pCO2, glucose). pCO2 sensors showed promising short response times of about 4 min whereas glucose and pH sensors displayed longer response times of several hours in phosphate-buffered saline solution. The combination of piezoresistive pressure sensors and stimuli-sensitive hydrogels enables a great diversity of detecting analytes as well as miniaturized and implantable sensors for continuous measuring of physiological parameters. However, to implant the sensors an encapsulation strategy is needed that secures the electronics as well as ensures the biocompatibility without loss of functionality and flexibility. For this, the devices were coated with the polymer parylene C and an additional layer of blockcopolymers composed of polyaminoacid (PAA) and polyethyleneglycol (PEG) blocks synthesized via ring-opening polymerization. The functionalization units are carried out by the PEG blocks whereas the PAA blocks perform as linker molecules onto the activated parylene C surface. After covalent coupling of blockcopolymers to the inert polymer the surface characteristics changed and hence the cell and blood compatibility was improved. Furthermore the stealth effect of the outwards PEG chains was utilized to reduce the adsorption of proteins like fibronectin or fibrinogen. These proteins play a major role in inflammatory processes, cell adhesion and blood coagulation. The results gave proof that the encapsulation leads to decisively reduced physiological reactions

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25

Möller, Lena [Verfasser]. "Funktionalisierung von Oberflächen und Hyaluronsäure-basierte Hydrogele für die Anwendung in der regenerativen Medizin / Lena Möller." Hannover : Technische Informationsbibliothek und Universitätsbibliothek Hannover (TIB), 2012. http://d-nb.info/1023627116/34.

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26

Trötschler, Tobias Michael [Verfasser], and Rolf [Akademischer Betreuer] Mülhaupt. "Schaltbare ionische Kammpolymere, Netzwerke, Polyisobutylen-Hydrogele und Gel-Polymer-Elektrolyte auf Basis von Poly-2-Oxazolin." Freiburg : Universität, 2020. http://d-nb.info/1230754245/34.

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27

Hennecke, Tobias [Verfasser], and Mathias [Akademischer Betreuer] Ulbricht. "Entwicklung kalium-sensitiver Hydrogele zur in vivo Anwendung in diagnostischen Implantaten / Tobias Hennecke ; Betreuer: Mathias Ulbricht." Duisburg, 2018. http://d-nb.info/1151446602/34.

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28

Friedrich, Tatjana [Verfasser]. "Intelligente Hydrogele durch strahleninduzierte Copolymerisation von mizellaren Lösungen aus Tensidmonomeren und N-Isopropylacrylamid oder Acrylsäure / Tatjana Friedrich." München : Verlag Dr. Hut, 2011. http://d-nb.info/1014848636/34.

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29

Rohn, Mathias [Verfasser], Brigitte [Akademischer Betreuer] Voit, and Sebastian [Gutachter] Seiffert. "Strukturcharakterisierung photochemisch vernetzter tetra-PEG Hydrogele mit unterschiedlichem Aufbau / Mathias Rohn ; Gutachter: Sebastian Seiffert ; Betreuer: Brigitte Voit." Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://d-nb.info/1142736342/34.

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30

Ehrenhofer, Adrian, Alice Mieting, Sascha Pfeil, Johannes Mersch, Chokri Cherif, Gerald Gerlach, and Thomas Wallmersperger. "An automatically rainproofing bike helmet through light-sensitive hydrogel meshes: Design, modeling and experiments." SPIE, 2020. https://tud.qucosa.de/id/qucosa%3A74218.

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For everyday cycling, one needs to carry rainproof clothing just for the case of unexpected downpours. In the present research, we present a concept for a helmet which is automatically rainproof when the rain starts. When the sun comes out, the helmet is breathable again even before it completely dries up. This functionality is provided by active hydrogel meshes. Hydrogel meshes offer great advantages due to their ability to change the aperture size with swelling and deswelling. In our current work, we present the design and modeling steps for hydrogel-layered active meshes which use (i) swelling and deswelling in hydrated state and (ii) swelling starting from the dry state. The main goal is to close the air openings of a bicycle helmet when rain starts as an automatic rainproofing. This can be achieved through the swelling of the hydrogel pNiPAAM-co-chlorophyllin in the meshes, which leads to closing when hydrated. At the same time, the light-sensitive behavior leads to opening of the apertures under direct sun exposure, i.e. when the sun appears again after the rain. We present the steps of modeling and design using the Normalized Extended Temperature-Expansion-Model (NETEM) to perform simulations in Abaqus. The model is capable of describing both the swelling of the hydrogel under light stimulus and the volume change due to hydration. It is based on the analogy between free swelling and thermal expansion and defined for nonlinear displacements. We also discuss the fabrication process of hydrogel-layered fibers and challenges in their application and simulation. As a proof of concept for hydrogel-layered meshes, we show preliminary experimental results of a poly(acrylamide)/poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAAm/PAMPS) hydrogel with semi-interpenetrated network (SIPN) structure and its swelling capacities on a mesh. Starting from the active hydrogel meshes as presented in the current work, the next step can be smart textiles that harness the power of hydrogels: the adaptation to combinations of stimuli - like humidity, temperature and brightness - that define environments.

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31

Martini, Maike Stefanie [Verfasser]. "Synthese Imidazol- und Triazol-haltiger Vernetzer auf Basis von Maleinimiden und Aminosäuren für Hyaluronsäure-Hydrogele / Maike Stefanie Martini." München : Verlag Dr. Hut, 2015. http://d-nb.info/1080754458/34.

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32

Kraus, Katharina Elisabeth [Verfasser], Bernd [Akademischer Betreuer] Tieke, and Annette [Akademischer Betreuer] Schmidt. "Funktionalisierte intelligente Hydrogele auf Basis von N-Isopropylacrylamid, Acrylsäure und Tensidmonomeren / Katharina Elisabeth Kraus. Gutachter: Bernd Tieke ; Annette Schmidt." Köln : Universitäts- und Stadtbibliothek Köln, 2014. http://d-nb.info/1068619767/34.

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33

Stratesteffen, Henrike [Verfasser], Horst [Akademischer Betreuer] Fischer, and Cordian [Akademischer Betreuer] Beyer. "Evaluierung des Angiogenese-Potenzials fotovernetzbarer Hydrogele und Hydrogelmischungen für das 3D Tissue Engineering / Henrike Stratesteffen ; Horst Fischer, Cordian Beyer." Aachen : Universitätsbibliothek der RWTH Aachen, 2017. http://d-nb.info/1162559918/34.

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34

Tronci, Giuseppe. "Synthesis, characterization, and biological evaluation of gelatin-based scaffolds." Phd thesis, Universität Potsdam, 2010. http://opus.kobv.de/ubp/volltexte/2011/4972/.

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This work presents the development of entropy-elastic gelatin based networks in the form of films or scaffolds. The materials have good prospects for biomedical applications, especially in the context of bone regeneration. Entropy-elastic gelatin based hydrogel films with varying crosslinking densities were prepared with tailored mechanical properties. Gelatin was covalently crosslinked above its sol gel transition, which suppressed the gelatin chain helicity. Hexamethylene diisocyanate (HDI) or ethyl ester lysine diisocyanate (LDI) were applied as chemical crosslinkers, and the reaction was conducted either in dimethyl sulfoxide (DMSO) or water. Amorphous films were prepared as measured by Wide Angle X-ray Scattering (WAXS), with tailorable degrees of swelling (Q: 300-800 vol. %) and wet state Young’s modulus (E: 70 740 kPa). Model reactions showed that the crosslinking reaction resulted in a combination of direct crosslinks (3-13 mol.-%), grafting (5-40 mol.-%), and blending of oligoureas (16-67 mol.-%). The knowledge gained with this bulk material was transferred to the integrated process of foaming and crosslinking to obtain porous 3-D gelatin-based scaffolds. For this purpose, a gelatin solution was foamed in the presence of a surfactant, Saponin, and the resulting foam was fixed by chemical crosslinking with a diisocyanate. The amorphous crosslinked scaffolds were synthesized with varied gelatin and HDI concentrations, and analyzed in the dry state by micro computed tomography (µCT, porosity: 65±11–73±14 vol.-%), and scanning electron microscopy (SEM, pore size: 117±28–166±32 µm). Subsequently, the work focused on the characterization of the gelatin scaffolds in conditions relevant to biomedical applications. Scaffolds showed high water uptake (H: 630-1680 wt.-%) with minimal changes in outer dimension. Since a decreased scaffold pore size (115±47–130±49 µm) was revealed using confocal laser scanning microscopy (CLSM) upon wetting, the form stability could be explained. Shape recoverability was observed after removal of stress when compressing wet scaffolds, while dry scaffolds maintained the compressed shape. This was explained by a reduction of the glass transition temperature upon equilibration with water (dynamic mechanical analysis at varied temperature (DMTA)). The composition dependent compression moduli (Ec: 10 50 kPa) were comparable to the bulk micromechanical Young’s moduli, which were measured by atomic force microscopy (AFM). The hydrolytic degradation profile could be adjusted, and a controlled decrease of mechanical properties was observed. Partially-degraded scaffolds displayed an increase of pore size. This was likely due to the pore wall disintegration during degradation, which caused the pores to merge. The scaffold cytotoxicity and immunologic responses were analyzed. The porous scaffolds enabled proliferation of human dermal fibroblasts within the implants (up to 90 µm depth). Furthermore, indirect eluate tests were carried out with L929 cells to quantify the material cytotoxic response. Here, the effect of the sterilization method (Ethylene oxide sterilization), crosslinker, and surfactant were analyzed. Fully cytocompatible scaffolds were obtained by using LDI as crosslinker and PEO40 PPO20-PEO40 as surfactant. These investigations were accompanied by a study of the endotoxin material contamination. The formation of medical-grade materials was successfully obtained (<0.5 EU/mL) by using low-endotoxin gelatin and performing all synthetic steps in a laminar flow hood.
Diese Arbeit beschreibt die Entwicklung Entropie-elastischer Gelatine-basierter Netzwerke als Filme und Scaffolds. Mögliche Anwendungen für die entwickelten Materialien liegen im biomedizinischen Bereich, insbesondere der Knochenregeneration. Im ersten Schritt der Arbeit wurden Entropie-elastische, Gelatine-basierte Hydrogel-Filme entwickelt, deren mechanische Eigenschaften durch die Veränderung der Quervernetzungsdichte eingestellt werden konnten. Dazu wurde Gelatine in Lösung oberhalb der Gel-Sol-Übergangstemperatur kovalent quervernetzt, wodurch die Ausbildung helikaler Konformationen unterdrückt wurde. Als Quervernetzer wurden Hexamethylendiisocyanat (HDI) oder Lysindiisocyanat ethylester (LDI) verwendet, und die Reaktionen wurden in Dimethylsulfoxid (DMSO) oder Wasser durchgeführt. Weitwinkel Röntgenstreuungs Spektroskopie (WAXS) zeigte, dass die Netzwerke amorph waren. Der Quellungsgrad (Q: 300-800 vol. %) und der Elastizitätsmodul (E: 70 740 kPa) konnten dabei durch die systematische Veränderung der Quervernetzungsdichte eingestellt werden. Die Analyse der Quervernetzungsreaktion durch Modellreaktionen zeigte, dass die Stabilisierung der Hydrogele sowohl auf kovalente Quervernetzungen (3-13 mol.-%) als auch auf Grafting von (5-40 mol.-%) und Verblendung mit Oligoharnstoffen (16-67 mol.-%) zurückgeführt werden kann. Die Erkenntnisse aus dem Umgang mit dem Bulk-Material wurden dann auf einen integrierten Prozess der Verschäumung und chemischen Quervernetzung transferiert, so dass poröse, dreidimensionale Scaffolds erhalten wurden. Dafür wurde eine wässrige Gelatinelösung in Gegenwart eines Tensids, Saponin, verschäumt, und durch chemische Quervernetzung mit einem Diisocyanat zu einem Scaffold fixiert. Die Scaffolds hergestellt mit unterschiedlichen Mengen HDI und Gelatine, wurden im trockenen Zustand mittels Mikro Computertomographie (µCT, Porosität: 65±11–73±14 vol.-%) und Rasterelektronenmikroskopie (SEM, Porengröße: 117±28–166±32) charakterisiert. Anschließend wurden die Scaffolds unter Bedingungen charakterisiert, die für biomedizinische Anwendungen relevant sind. Die Scaffolds nahmen große Mengen Wasser auf (H: 630 1680 wt.-%) bei nur minimalen Änderungen der äußeren Dimensionen. Konfokale Laser Scanning Mikroskopie zeigte, dass die Wasseraufnahme zu einer verminderten Porengröße führte (115±47–130±49 µm), wodurch die Formstabilität erklärbar ist. Eine Formrückstellung der Scaffolds wurde beobachtet, wenn Scaffolds im nassen Zustand komprimiert wurden und dann entlastet wurden, während trockene Proben in der komprimierten Formen blieben (kalte Deformation). Dieses Entropie-elastische Verhalten der nassen Scaffolds konnte durch die Verminderung der Glasübergangstemperatur des Netzwerks nach Wasseraufnahme erklärt werden (DMTA). Die zusammensetzungsabhängigen Kompressionsmoduli (Ec: 10 50 kPa) waren mit den mikromechanischen Young’s moduli vergleichbar, die mittels Rasterkraftmikroskopie (AFM) gemessen wurden. Das hydrolytische Degradationsprofil konnte variiert werden, und während des Abbaus kam es nur zu kontrolliert-graduellen Änderungen der mechanischen Eigenschaften. Während der Degradation konnte ein Anstieg der mittleren Porengröße beobachtet werden, was durch das Verschmelzen von Poren durch den Abbau der Wände erklärt werden kann. Die Endotoxinbelastung und die Zytotoxizität der Scaffolds wurden untersucht. Humane Haut-Fibroblasten wuchsen auf und innerhalb der Scaffolds (bis zu einer Tiefe von 90 µm). Indirekte Eluat-Tests mit L929 Mausfibroblasten wurden genutzt, um die Zytotoxizität der Materialien, insbesondere den Einfluss des Quervernetzertyps und des Tensids, zu bestimmen. Vollständig biokompatible Materialien wurden erzielt, wenn LDI als Quervernetzer und PEO40 PPO20-PEO40 als Tensid verwendet wurden. Durch den Einsatz von Gelatine mit geringem Endotoxin-Gehalt, und die Synthese in einer Sterilarbeitsblank konnten Materialien für medizinische Anwendungen (Endotoxin-Gehalt < 0.5 EU/mL) hergestellt werden.

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35

Rauner, Jan Nicolas [Verfasser], Jörg C. [Akademischer Betreuer] Tiller, and Jörg [Gutachter] Kreßler. "Funktionale anorganisch/organische Hybridmaterialien für ultrasteife Hydrogele und antimikrobielle Lotusoberflächen / Jan Nicolas Rauner ; Gutachter: Jörg Kreßler ; Betreuer: Jörg C. Tiller." Dortmund : Universitätsbibliothek Dortmund, 2017. http://d-nb.info/1136471588/34.

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36

Horecha, Marta. "Coatings with Inversely Switching Behavior. New Applications of Core-Shell Hydrogel Particles." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-65171.

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The main goal of this work is design and synthesis of novel composite hydrogel-based core-shell microparticles and their application for fabrication of coatings, which provide the “inverse-switching” behaviour to the surface, namely, to become more hydrophobic in water environment. Since contact angle of heterogeneous surfaces is dependent on the nature and ratio of surface components, an increase of amount of more hydrophobic component on the surface will cause the reducing of surface wettability. It was suggested that core-shell particles having water-swellable hydrogel core and hydrophobic, but permeable for water shell when deposited on the hydrophilic substrate should increase the total amount of hydrophobic component on the surface when the cores of particles will swell in water. During the work different approaches to obtain freely dispersed and surface-immobilized core-shell particles with required structure were developed. Obtained particles were applied for preparation of coatings with ability to display “inverse-switching” behaviour. It was demonstrated that properly designed and properly prepared core-shell particles could be successfully used for creation of smart adaptive coatings having the ability to alter the surface properties upon changing of the environment.

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Ehrenhofer, Adrian, and Thomas Wallmersperger. "Hydrogels for engineering." SPIE, 2017. https://tud.qucosa.de/id/qucosa%3A34890.

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In engineering, materials are chosen from databases: Engineers orient on specific parameters such as Young's modulus, yield stress or thermal expansion coefficients for a desired application. For hydrogels, the choice of materials is rather tedious since no generalized material parameters are currently available to quantify the swelling behavior. The normalization of swelling, which we present in the current work, allows an easy comparison of different hydrogel materials. Thus, for a specific application like a sensor or an actuator, an adequate material can be chosen. In the current work, we present the process of normalization and provide a course of action for the data analysis. Special challenges for hydrogels like hysteresis, conditional multi-sensitivity and anisotropic swelling are addressed. Then, the Temperature Expansion Model is shortly described and applied. Using the derived normalized swelling curves, a nonlinear expansion coefficient β(F) is derived. The derived material behavior is used in an analytical model to predict the bending behavior of a beam made of thermo-responsive hydrogel material under an anisotropic temperature load. A bending behavior of the beam can be observed and the impact of other geometry and material parameters can be investigated. To overcome the limitations of the one-dimensional beam theory, the material behavior and geometry can be implemented in Finite Element analysis tools. Thus, novel applications for hydrogels in various fields can be envisioned, designed and tested. This can lead to a wider use of smart materials in sensor or actuator devices even by engineers without chemical background.

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38

Bernuth, Silvia [Verfasser], and Torsten [Gutachter] Blunk. "Bioaktiv funktionalisierbare Hyaluronsäure-Polyglycidol-Hydrogele unter Verwendung von ASCs aus dem Fettgewebe zur Rekonstruktion von Weichgewebsdefekten / Silvia Bernuth ; Gutachter: Torsten Blunk." Würzburg : Universität Würzburg, 2020. http://d-nb.info/1220244554/34.

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39

Beyer, Antje [Verfasser], Jürgen [Gutachter] Popp, and Felix [Gutachter] Schacher. "3D-Hydrogele als Interaktionsmatrix für eine Chip-basierte DNS-Spurenanalyse in Vor-Ort-Anwendung / Antje Beyer ; Gutachter: Jürgen Popp, Felix Schacher." Jena : Friedrich-Schiller-Universität Jena, 2016. http://d-nb.info/117761099X/34.

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40

Passauer, Lars. "Beiträge zur Entwicklung Wasser speichernder Materialien auf Basis von Stärke und Lignin." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1218103243285-95634.

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Vor dem Hintergrund des weltweit wachsenden Bedarfes an Bodenverbesserungsmitteln, durch die Humus-, Nährstoff- und Wassermangel auf Problemstandorten kompensiert werden sollen, war es das Ziel der vorliegenden Arbeit, Bodenwasser-speicher auf Basis der nachwachsenden Biopolymere Stärke und Lignin zu entwickeln. Durch Derivatisierung der Stärke wurde deren Hydrophilie deutlich gesteigert, was Voraussetzung für die Bildung von Hydrogelen war. Es konnte gezeigt werden, dass durch Vernetzung der wasserlöslichen Stärkederivate Carboxymethylstärke und Monostärkemonophosphat mit Di-/Tricarbonsäuren quellfähige Hydrogele erzeugt werden, deren Quellungsvermögen und rheologische Eigenschaften über die Wahl des Vernetzers und die Vernetzerstoffmenge gezielt eingestellt werden können. Die Modifizierung von Lignin wurde durch Oxidation mit Wasserstoffperoxid, z.T. in Kombination mit Fe(II)- bzw. Mn(II)-Chloriden realisiert. Dadurch wurde die Vernetzbarkeit von Lignin deutlich verbessert, was auf oxidativ bedingte Strukturänderungen des Lignins zurückzuführen war. Diese bestanden im Wesentlichen in der Spaltung und Oxidation der Lignin-Seitenkette sowie der Hydroxylierung der Seitenkette und aromatischer Strukturen. Die Vernetzung von Lignin mit Poly-(ethylenglycol)-diglycidylether ergab quellfähige Hydrogele, deren Wasseraufnahmevermögen und rheologische Materialfunktionen von der eingesetzten Vernetzerstoffmenge abhängig sind. Es konnte gezeigt werden, dass durch den Einsatz von Stärkephosphat- und Lignin-Hydrogelen das Wasserspeichervermögen erhöht und die Evaporationsraten eines entsprechend behandelten Sandbodens verringert werden. Im Wachstumsversuch wurden die Frischmasseerträge von Gelbsenf (Sinapis alba) durch Behandlung eines Sandbodens mit Hydrogelen gesteigert
Soil degradation leading to a lack of humus, nutrients and water especially on exploited sites causes the worldwide need in soil amendments. Aim of the work was the development of hydrogels from renewable biopolymers starch and lignin improving water retention especially in degraded soils. A significant increase of hydrophilic properties of starch was obtained by chemical modification with the objective of forming starch based hydrogels. Swellable hydrogels were formed by cross-linking of water soluble starch derivatives like carboxymethyl starch and monostarch monophosphates with di- and tricarboxylic acids. Swelling capacity and rheological properties of the starch gels were selective adjusted by variation of cross linking agent and whose amounts. Modification of lignin was realized by oxidation with hydrogen peroxide partly in combination with ferrous and manganese chlorides, respectively. In consequence of oxidative structural changes which were cleavage and oxidation of side chain as well as aliphatic and aromatic hydroxylation, gelation of lignin was improved significant. Lignin hydrogels with different swelling capacities and rheological functions were formed by cross-linking lignin with different amounts of poly (ethylene glycol) diglycidyl ether. Application of hydrogels based on starch and lignin causes increased water storing capacity/field capacity and decreased evaporation of a sandy soil as well as an increased biomass yield of yellow mustard (Sinapis alba)

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41

Abdelmoneim, Ibrahim Mohamed Ibrahim. "Synthesis, structural and supramolecular studies of linear and cyclic 2 1-[α/aza]-oligomers." Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0159.

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La première partie de cette thèse concerne la synthèse et les études structurales de 2:1-[α/aza]-oligomères linéaires et cycliques possédant des acides aminés hydrophobes et/ou basiques. Les études RMN et IRTF ont démontré que les oligomères adopteraient des conformations de type coude β en solution. Les calculs de dynamiques moléculaires des oligomères à base de résidus lysine ont révèlé l’importance du motif aza dans le repliement de ces oligomères indépendamment de l’impact de la chaîne latérale. Les études par DRX, IRTF et RMN ont révélé que les deux hexamère cycliques (L- ou D-Phe-azaPhe-Ala)2 homo- et hétérochiraux adoptent des conformations de type coude ß en solution et à l’état solide. Ils s’organisent en structures 3D très ordonnées, stabilisées par des ponts hydrogènes et des empilements π. La deuxième partie démontre l'auto-assemblage de quelques 2:1-[α/aza]-oligomères dans certains solvants pour former des gels supramoléculaires. Le cyclooligomère hétérochiral (D-Phe-azaPhe-Ala)2 peut former des organogels. La spectroscopie et rhéologie des organogels ont révélé de bonnes stabilités thermique et mécanique avec un comportement de type solide. La MEB/MET de l'aérogel a montré une structure fibreuse 3D. De plus, deux hydrogels Fmoc-D- ou L-Phe-azaPhe-Ala-OH ont été obtenus aux pH 7.0 et 10.0. Les spectres UV et de fluorescence ont révélé une stabilisation des hydrogels par interaction π entre les groupes aromatiques. Leur analyse par CD montre que les trimères s'auto-assemblent sous forme de feuillet β en accord avec les résultats ATR/IRTF. Ainsi, leurs études rhéologiques ont révélé un comportement de type solide. La MEB des xérogels a montré une structure fibreuse. La troisième partie propose deux applications; (i) les oligomères à base de résidus lysine ont révélé de bonnes performances pour la séparation CO2/N2 dans des membranes polymères Pebax®, et (ii) le cyclohexamère hétérochiral (D-Phe-azaPhe-Ala)2 convient pour la gélification sélective avec un bon pourcentage de récupération
The first part of this thesis reported the synthesis and structural studies of linear and cyclic 2:1-[α/aza]-oligomers possessing hydrophobic and/or basic amino acids (lysine). NMR and FTIR results demonstrated that the oligomers could adopt β-turn conformations in solution. Molecular dynamic calculations for oligomers based lysine residues reflected the important role of the aza-motif(s) in structuring the backbones regardless the chirality and nature of the amino acids. In the other hand, X-ray, FTIR, and NMR studies showed that homo- and heterochiral cyclo-(L- or D-Phe-azaPhe-Ala)2-hexamers adopt β-turn conformations in solution and solid states. Both molecules could organize into 3D highly ordered structures stabilized by hydrogen bonds and π-stacking. The second part reflected the propensity of some 2:1-[α/aza]-oligomers to self-assemble in some solvents to form supramolecular gels. Interestingly, the heterochiral cyclo-(D-Phe-azaPhe-Ala)2-hexamer could form organogels. The spectroscopic and rheological studies of the organogels revealed good thermal and mechanical stability with solid-like behavior. SEM and TEM images of the aerogel showed fibrous structure. Furthermore, two hydrogelators, Fmoc-D- or L-Phe-azaPhe-Ala-OH, have been developed and they could achieve hydrogels at pHs 7.0 and 10.0. UV and Flu studies demonstrated that the hydrogels are supported by π-stacking between the aromatic groups. CD analysis reflected that the two hydrogelators self-assemble into β-sheet like structure in consistent with ATR-FTIR results. Both hydrogels exhibited solid-like behavior through rheological studies and the SEM analysis of the xerogels revealed fibrous structure. The third part offered two applications; (i) oligomers based lysine residues reflected good performances in CO2/N2 separation when used as additives in polymeric Pebax® membrane, and (ii) the heterochiral cyclo-(D-Phe-azaPhe-Ala)2-hexamer is suitable for phase selective gelation with good recovery percentages

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42

Ehrenhofer, Adrian, and Thomas Wallmersperger. "Active hydrogel composite membranes for the analysis of cell size distributions." SPIE, 2019. https://tud.qucosa.de/id/qucosa%3A74237.

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Active membranes with switchable pores that are based on hydrogels can be used to measure the cell size distribution in blood samples. The system investigated in the present research is based on a polyethylene terephthalate (PET) membrane that is surface polymerized with poly (N-isopropyl acrylamide) (PNiPAAm) to form active pores of arbitrary geometry. The PET membrane provides the functionality of a backbone for mechanical rigidity, while the soft PNiPAAm hydrogel forms the active pores. Modeling and simulation of the active hydrogel behavior proved to adequately predict the opening and closing of the pores under application of an activating stimulus, e.g. temperature. The applied model is called Temperature-Expansion-Model and uses the analogy of thermal expansion to model the volume swelling of hydrogels. The Normalized Extended Temperature-Expansion-Model can englobe arbitrary hydrogels and large geometric displacements. Studies of pore opening - performed by using commercial finite element tools - show good agreement of the experimentally measured shape change of active pores. Based on these studies, the particulate fluid flow through the switchable pores is analyzed. Through application of a membrane process, i.e. a given variation of applied pressure and switching stimulus for the hydrogel, the size profile of the blocking particles can be measured directly using the flux difference under constant pressure. This allows the measurement of the cell size distribution in blood samples, e.g. to detect circulating tumor cells or anomalies in the distribution that hint to anemia.

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43

Castillo, Moreno Patricia. "Développement d'un procédé de production d'hydrogène photofermentaire à partir de lactosérum." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAI029/document.

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L'hydrogène est une source d'énergie précieuse en tant que source d'énergie propre et que matière première pour des innombrables industries.Les procédés biologiques de production d'hydrogène gagnent en importance en raison de leurs avantages opérationnelles et de leur polyvalence dans les substrats utilisés (y compris les eaux usées).Dans cette thèse doctoral, on a développé une méthodologie photo-fermentative de production d'hydrogène en utilisant du lactosérum en tant que substrat pour la bactérie Rhodobacter capsulatus IR3::LacZ et B10::LacZ.Ce projet a été réalisé en trois étapes, exposées dans les différents chapitres.Dans la première étape on a identifié les facteurs pertinents pour la production de l'hydrogène avec du sérum synthétique en utilisant la méthodologie de plan d'expériences.Les résultats de cet étape on a obtenu quatre modèles statistiques et on a choisi la souche IR3::LacZ pour les expériences avec du lactosérum industriel.Le rendement volumétrique maximal et le rendement produit / substrat Y P/S obtenus pour la première étape ont été de 64 ml h-1L-1 et 2,08 mol H2 mol-1 C (“C” représente la source de carbone dans ce cas lactose et lactate) pour la solution amortissant le phosphate et 43.01 ml h-1L-1 y 2.52 mol H2 mol-1 C pour la solution Kolthoff.Dans la deuxième étape, on a évalué la production d'hydrogène avec du lactosérum industriel. On a appliqué un pré-traitement de trois étapes avant d'utiliser le lactosérum comme substrat : réduction du contenu gras, déprotéinisation et stérilisation. On a obtenu un modèle validé qui décrit la production d'hydrogène seulement pour la solution amortissant de phosphate. Le rendement volumétrique maximal et le YP/S ont été de 45.93 ml h-1L-1 et de 2.29 mol H2 mol-1 C respectivement. On a déterminé que l'addition d'une étape d’homo-fermentation au processus de prétraitement es avantageuse au rendement du processus. On a obtenu une productivité volumétrique de 69.71 ml h-1L-1 et de YP/S de 2.96 mol H2 mol-1 CLa troisième étape a été la mise à l'échelle des expériences à réacteurs de 1,5 L pour sérum synthétique et de 1L pour serum industriel. On a décelé de la contamination dû à la présence d'un processus de fermentation, lequel a généré une haute production de biogas composé exclusivement par H2 y CO2 ce dernier dans une concentration non superieur à 30% (v/v).Pour ces raisons, on a conclu que conclu que le processus de production intégré, en couplant la fermentation obscure et la photo-fermentation est une option avec un énorme potentiel pour l'utilisation de lactosérum comme substrat dans la production d'hydrogène
Hydrogen is a valuable gas use as a clean energy source and feedstock for some industries. Biological hydrogen production processes are gaining importance due to their operational conditions and versatility in the substrates (including wastewater). A hydrogen production photo fermentative methodology was developed using cheese whey as a substrate for the bacteria Rhodobacter capsulatus strain IR3::LacZ and B10::LacZ . The project was carried out in three stages.The purpose of the first stage is to identify the relevant factors to produce hydrogen for a synthetic whey medium in a photofermentation process, using the Design of Experiments methodology. The products of this stage are four statistical models, obtained for each strain and buffer solution studied. The strain IR3::LacZ was selected for the experiments with industrial whey as substrate. The maximum volumetric yield and the product/substrate yield YP/S were 64 ml h-1L-1 and 2.08 mol H2 mol-1 C (C is the carbon source in this case lactose and lactate) and 43.01 ml h-1L-1 and 2.52 mol H2 mol-1 C for phosphate buffer and Kolthoff buffer, respectively.In the second stage the production of hydrogen with industrial whey was evaluated. A three-step pre-treatment was applied before using industrial cheese whey as substrate: fat reduction, deproteinization and sterilization. A validate statistical model describing hydrogen production was only obtained for phosphate buffer. The maximum volumetric yield and the product/substrate yield YP/S were 45.93 ml h-1L-1 and 2.29 mol H2 mol-1 C respectively. The addition of an homofermentation to the pretreatment improved the production yield, in this case a volumetric productivity of 69.71 ml h-1L-1 and a YP/S of 2.96 mol H2 mol-1 C were obtained.The third stage was the scale-up to 1.5 and 1 reactor L for synthetic whey and 1L for synthetic and industrial whey respectively. A fermentative process appeared due to a bacterial contamination, leading to a high biogas production. Biogas was exclusively composed of H2 and CO2 the last in a concentration not exceeding 30% (v/v). For this reason, it was concluded that the integrated production process coupling dark and photo fermentations) is an option with great potential for the use of whey as substrate in the production of hydrogen

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44

Pătru, Alexandra. "Développement de catalyseurs pour un électrolyseur alcalin H2/O2." Thesis, Montpellier 2, 2013. http://www.theses.fr/2013MON20012.

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Le travail de thèse présenté dans ce mémoire, est consacré à l'étude des nouveaux matériaux d'électrodes pour l'électrolyse de l'eau en milieu alcalin. L'objectif de ces études est de développer de nouveaux électrocatalyseurs à base de métaux non nobles, capables d'améliorer les cinétiques de réactions intervenant dans la décomposition de l'eau : l'évolution de l'hydrogène (HER) et l'évolution de l'oxygène (OER). L'amélioration des performances catalytiques se traduit par une diminution des surtensions de réaction et donc de l'énergie nécessaire à la production de l'hydrogène. Pour cela, nous avons choisir de réaliser des électrodes à base de nanoparticules de nickel et de cobalt pour l'HER et de nanoparticules de cobaltites de cobalt, Co3O4, pour l'OER. La mise au point de plusieurs méthodes innovantes de formulation des électrodes (dépôt par électrophorèse « réactive » et électrodes composites à base liant organique fonctionnel) a permis la réduction des surtensions des réactions. Pour une densité de courant de 100 mA cm-2, une surtension cathodique de -286 mV est nécessaire avec les électrodes composites à base de nanoparticules de nickel, -238 mV pour une électrode en Co obtenue par électrophorèse et une surtension anodique 323 mV pour une électrode composite à base de nanoparticules de Co3O4. Une étude électrochimique approfondie de l'HER a été réalisée sur différentes morphologies de nanoparticules de nickel
The PhD work, presented in this manuscript, is devoted to the study of new electrode materials for alkaline water electrolysis.The aim of this study is to develop new electrocatalysts based on non-noble metals. These catalysts are designed to improve the kinetics of the reactions involved in the water splitting: hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The improvement of catalytic reaction results in the decrease of the overpotentials and therefore the saving of energy needed for hydrogen production. To do that, nickel and cobalt nanoparticles were used for HER, and Co3O4 nanoparticles for OER. The development of several innovative methods for electrode formulation (deposition by electrophoresis and composites electrodes based on a functional organic binder) reduced the overpotential reactions. For a current density of 100 mA cm-2, -286 mV of cathodic overpotential is needed for composites electrodes based on nickel nanoparticles, -238 mV for a Co-based electrode made by electrophoresis and 323 mV of anodic overpotential for a Co3O4 -based composite electrode. A detailed electrochemical study was made for HER on various morphologies of nickel nanoparticles

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45

Corten, Cathrin Carolin. "Synthese und Charakterisierung dünner Hydrogelschichten mit modulierbaren Eigenschaften." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2008. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1209463829168-95283.

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Im Mittelpunkt dieser Arbeit stand die Darstellung sensitiver Blockcopolymere und deren Gele, die als Ausgangsmaterialien in Sensor- und Aktorsystemen einsetzbar sind. Die Vereinigung verschiedener Ansprechparameter stellt erhöhte Anforderung an die Synthese. Geringe Ansprechzeiten lassen sich mit einer Gelgröße im µm-Bereich erreichen. Hydrogele dieser Größenordnungen können durch nachträgliche Vernetzung funktioneller linearer Polymere ermöglicht werden. Die Makroinitiatormethode ermöglichte den Aufbau verschiedener linearer photovernetzbarer Blockcopolymere. Zum Einen wurde das temperatursensitive P(n-BuAc)-block-P(PNIPAAm-co-DMIAAm) erhalten, des Weiteren gelang die Darstellung der multi-sensitiven Blockcopolymere P2VP-block-P(NIPAAm-co-DMIAAm) und P4VP-block-P(NIPAAm-co-DMIAAm). Die Blockcopolymere wurden mit variierenden Blocklängen und Verhältnissen sowie mit unterschiedlichem Vernetzergehalt dargestellt. Die Charakterisierung der Blockcopolymere erfolgte mittels 1H-NMR-Spektroskopie, GPC-Messungen (Zusammensetzung) und DSC-Messungen (thermische Eigenschaften). Das Löslichkeitsverhalten in wässrigen Medien wurde durch Dynamische Lichtstreuung bestimmt. Die Beschreibung des Quellverhaltens der vernetzten Schichten erfolgte durch vornehmlich durch optische Methoden (SPR/OWS, WAMS, Ellipsometrie). Die Veränderung des E-Moduls in Abhängigkeit äußerer Parameter konnte mittels AFM untersucht werden. Die Reaktion der Schichten wurde gegenüber Temperatur, pH-Wert und Salzkonzentrationen getestet. Die charakterisierten Filme konnten im Anschluss als sensitive Schichten in piezoresistiven Sensorsystemen verwendetet werden.

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Ehrenhofer, Adrian, Martin Elstner, Angelos Filippatos, Maik Gude, and Thomas Wallmersperger. "Window-opener as an example for environment measurement and combined actuation of smart hydrogels." SPIE, 2021. https://tud.qucosa.de/id/qucosa%3A74726.

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An environment is defined by a set of field values, such as temperature, electro-magnetic field, light intensity, air humidity and air composition. Smart materials, such as hydrogels, are able to react to these kinds of stimuli. The spatial and time development of environmental values is governed by transport equations. Hence the reaction, i.e. actuation or sensing, of the smart material can be described based on the same assumptions. The displacement, here swelling and deswelling, of the material depends on the combination of the environmental parameters. Smart materials are called multi-sensitive, when more than one parameter is purposely used (i) to manipulate the material, i.e. as an actuator or (ii) to measure the quantities, i.e. as a (multi-)sensor. However, the material can also perform (iii) the objective of a logic processing unit in addition to (i) and (ii). In the current work, we present a device that realizes this concept: An automatic window opener that senses environmental parameters (light-level and air temperature) and reacts accordingly. The hydrogel material that is included in the simplistic device simultaneously acts as sensor, logic processing unit and actuator.

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Dijk-Wolthuis, Welmoed van. "Biodegradable dextran hydrogels for pharmaceutical applications = Bioafbreekbare dextraan-hydrogelen voor farmaceutische toepassingen /." [S.l. : s.n.], 1997. http://www.gbv.de/dms/bs/toc/238021521.pdf.

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Ehrenhofer, Adrian, Manfred Hahn, Martin Hofmann, and Thomas Wallmersperger. "Mechanical behavior and pore integration density optimization of switchable hydrogel composite membranes." Sage, 2019. https://tud.qucosa.de/id/qucosa%3A74211.

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Switchable hydrogel-layered composite membranes can be used for the analysis of particle size distributions. This functionality is provided by pores with controllable diameter. In order to obtain a device that can be used to measure the cell size distribution in native biological samples, lots of switchable pores are required. In the current work, we model and simulate the mechanical behavior of active composite membranes with switchable pores. This is done in order to find the maximum number of pores that can be integrated into a membrane without cross-influencing effects on the actuation of the pores. Therefore, we investigate (1) the interaction of active pores inside the multifunctional composite and (2) the membrane bending under microfluidic pressure load. We show that through miniaturization, sufficient pores can be added to a permeation control membrane for processing native blood samples. The envisioned device allows a parallelized measurement of cell sizes in a simple lab-on-a-chip setup.

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Voigt, Andreas, Uwe Marschner, and Andreas Richter. "Multiphysics equivalent circuit of a thermally controlled hydrogel microvalve." Sage, 2017. https://tud.qucosa.de/id/qucosa%3A35628.

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Temperature-responsive hydrogels are polymer particles whose equilibrium size depends on the temperature of the water they are immersed in. Here we present an equivalent circuit model of a temperature-controlled microvalve based on hydrogel particles. The resulting network model consists of three physical subsystems. The thermal subsystem considers the heat capacities and thermal resistances of the layers of the valve and the coupling to the ambient environment. The polymeric subsystem describes the relaxation of the hydrogel particles to the temperature-dependent equilibrium size. The fluidic subsystem consists of the supply channel and a chamber whose cross section varies according to the size of the hydrogel particles. All subsystems are described and coupled within one single circuit. Thus the transient behavior of the valve can be calculated using a circuit simulator. Simulation results for a setup are presented and compared with experiments.

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Oborná, Jana. "Studium degradace biokompatibilních kopolymerů." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2011. http://www.nusl.cz/ntk/nusl-216802.

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This diploma thesis is focused on biocompatible polymers degradation study. Copolymers were studied based on poly(lactic-co-glycolic) acid and poly(ethylene glycol) PLGA-PEG-PLGA and further these copolymers modified with itaconic acid ITA-PLGA-PEG-PLGA-ITA. This paper investigated the influence of pH phosphate solution on the degradation of polymers. Degradation of polymers occurred at 37 °C in phosphate solution with pH 4.2, 7.4 and 9.2. High performance liquid chromatography with UV-VIS detection of diode-array type was used for quantitative determination of lactic acid and glycolic acid as the final degradation products. For qualitative identification of additional degradation products were used tandem connection liquid chromatography and mass spectrometry. Gel permeation chromatography with refractive index detector was used to determine the molecular weight decrease polymer chain after the degradation.

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