657 research outputs found
What increases (social) media attention: Research impact, author prominence or title attractiveness?
Do only major scientific breakthroughs hit the news and social media, or does
a 'catchy' title help to attract public attention? How strong is the connection
between the importance of a scientific paper and the (social) media attention
it receives? In this study we investigate these questions by analysing the
relationship between the observed attention and certain characteristics of
scientific papers from two major multidisciplinary journals: Nature
Communication (NC) and Proceedings of the National Academy of Sciences (PNAS).
We describe papers by features based on the linguistic properties of their
titles and centrality measures of their authors in their co-authorship network.
We identify linguistic features and collaboration patterns that might be
indicators for future attention, and are characteristic to different journals,
research disciplines, and media sources.Comment: Paper presented at 23rd International Conference on Science and
Technology Indicators (STI 2018) in Leiden, The Netherland
Mathematical modeling of mixed convection in a closed rectangular area in conditions of lower boundary radiant heating
Mathematical modeling of mixed convection in a closed rectangular area in conditions of lower boundary radiant heating is passed. Fields of temperatures and stream functions for different Grashof numbers are obtained. The scale influence of Grashof number increasing on the heat transfer intensity is shown. It is founded that the process of closed areas radiant heating has significantly unsteady nature
Some Have Other Crisis Concerns: Antecedents of Anxiety while Grocery Shopping
This study relates consumer behaviour with social disruption theory by identifying the antecedents of anxiety related to grocery shopping. Our research design integrates cognitive, behavioural, self-identity, emotional components in disruptive situations. This study presents a conceptual framework focusing on the cognitive and behavioural antecedents of anxiety relating to grocery shopping in disruptive situations. The conceptual model was validated by fitting a SEM with the FIMIX-PLS algorithm to 228 responses obtained an online questionnaire in Brazil and Germany. Two distinct segments of consumers—concerned and scared consumers—differing by their perceived vulnerability are identified. Concerned consumers are characterized by a strong relation of personal concerns to anxiety. The empirical contribution roots in the identification of two types of customers with respect to concerns and anxiety: (i) the concerned because of their situational awareness and (ii) those with more pressing problems. Thus, our study contributes to consumer behaviour and social disruption theory by clarifying and quantifying the impact of the antecedents of anxiety related to grocery shopping in crises. The resulting data from survey responses are cross-sectional, which means it cannot provide evidence of temporal sequence. Retailers benefit from actively shaping consumers’ emotional experiences through measures. The perceived consumers’ need for coping strategies to reduce their anxiety (e.g., shopping in less frequented stores) can thereby be eliminate
Intuitive and Deliberative Decision-Making in Negotiations
This study departs from common conjecture by challenging the preference for deliberation or intuition, or both, in negotiations. In contrast to prior negotiation studies considering judgment precision, this study builds on underlying personality traits. Therefore, the findings are valid beyond the experimental context. This study conceptualizes and experimentally tests the impact of preference for intuitive and deliberate decision-making during negotiations in Chinese, German, and Polish cultures. Contrasting an emotional with a neutral setting, the paper evaluates the impact preference for intuition and deliberation have on negotiation outcome. The results challenge the frequent assumption made in negotiation analysis: Deliberative negotiators are superior
Cryoglobulinaemic vasculitis: classification and clinical and therapeutic aspects
Cryoglobulinaemia may cause cutaneous vasculitis and glomerulonephritis, potentially leading to end stage renal failure. An important proportion of cryoglobulinaemias are secondary to hepatitis C virus infection. Emerging antiviral treatment options offer a chance for causal therapy of these cases of cryoglobulinaemia. This review summarises the classification and clinical and therapeutic aspects of cryoglobulinaemic vasculitis and glomerulonephritis
Impact Assessment of Land-Use Change and Agricultural Treatments on Greenhouse Gas Emissions from Wetlands of Uganda and Tanzania
Wetlands play an important role in global climate regulation as they represent a great global carbon sink. Moreover, wetlands provide optimal conditions for food production and support the livelihoods of many people in Sub-Saharan Africa with food supply. The conversion of natural wetland areas to farmland seriously affects valuable ecosystem services, including global climate regulation, and can result in altered greenhouse gas (GHG) emissions. Therefore, a main challenge of sustainable wetland management is to find a reconciliation between food production and mitigation of GHG emissions. For the development of management recommendations, GHG emission data from wetlands in Sub-Saharan Africa are highly needed, because the numbers of GHG studies conducted in this region are low. This study aimed to reduce this knowledge gap and assessed GHG emissions from wetlands in East Africa with consideration of contrasting wetland types, different types of land use and different hydrological positions within the wetland. Moreover, different agricultural treatments were evaluated with respect to their effects on yield-based GHG emissions. Two field experiments were established in different wetland types in East Africa. The first test site was located in an inland valley wetland in Uganda, while the second one was located in a floodplain of the Kilombero river in Tanzania. CH4, CO2 and N2O emission data were collected with static chambers for a total sampling period of two consecutive cropping and fallow periods. During data analysis, a lack of systematic quality assurance of GHG data from static chamber measurements became apparent. Thus, an eight-step data quality management system based on objective criteria was developed to ensure data reliability and improve data acceptance rates. The quality-checked results of this study confirmed that land-use change had a significant impact on GHG emissions, as the global warming potential (GWP) considerably increased after the conversion of natural wetlands to farmland. Moreover, this study showed that intensification of food production did not result in significantly higher yield-based GHG emissions. Intensive cropping treatments with fertilizer application showed equally high or even lower global warming potential indexes (GWPI) compared to non-fertilized treatments. In conclusion, intensive cropping management practices with high yield potentials represent a possible trade-off between food production and GHG emissions. However, to achieve GHG emission mitigation, a combination with natural wetland areas spared from agricultural production is essential.Folgenabschätzung von Landnutzungsänderung und landwirtschaftlichen Anbaumethoden auf Treibhausgasemissionen aus Feuchtgebieten in Uganda und Tansania Feuchtgebiete sind von entscheidender Bedeutung für die Regulierung des globalen Klimas, da sie eine maßgebliche, globale Kohlenstoffsenke darstellen. Außerdem bieten Feuchtgebiete optimale Bedingungen für den Anbau von Nahrungsmitteln und unterstützen somit die Lebensmittelversorgung vieler Menschen in Regionen Afrikas südlich der Sahara. Die Umwandlung von natürlichen Feuchtgebieten zu Ackerland beeinträchtigt jedoch viele wertvolle Ökosystemdienstleistungen, wie beispielsweise die Regulierung des globalen Klimas. Veränderte und erhöhte Treibhausgas-(THG)-Emissionen können die Folge sein. Eine der größten Herausforderungen hinsichtlich des nachhaltigen Managements von Feuchtgebieten besteht in der Schlichtung von Interessenkonflikten und einer Kompromissfindung zwischen Nahrungsmittelanbau und verminderten THG-Emissionen. Um nachhaltige Managementempfehlungen entwickeln zu können, werden dringend THG-Emissionsdaten von afrikanischen Feuchtgebieten benötigt. Die Zahl der derzeit existierenden Studien ist gering, wodurch die Datenlange große Lücken aufweist. Die vorliegende Studie verfolgte das Ziel, einen Beitrag zur Verringerung dieser Datenlücken zu leisten. Im Rahmen des Vorhabens wurden THG-Emissionsdaten von Feuchtgebieten in Ost-Afrika in Hinblick auf unterschiedliche Feuchtgebietstypen, Landnutzungsformen und Positionen im Feuchtgebiet erhoben. Zudem wurden verschiedene Anbaumethoden untersucht und hinsichtlich ihrer mindernden Wirkung auf THG-Emissionen gemäß ihres Ertrags beurteilt. Zwei Feldexperimente wurden in unterschiedlichen Feuchtgebietstypen Ost-Afrikas etabliert. Bei dem Ersten handelte es sich um ein Feuchtgebiet im Landesinneren von Uganda, das Zweite war ein Überflutungsgebiet am Kilombero-Fluss in Tansania. CH4-, CO2- und N2O-Emissionsdaten wurden mit statischen Kammermessungen über einen Zeitraum von zwei aufeinanderfolgenden Anbau- und Brachperioden erhoben. Während der Datenanalyse wurde ein Mangel an systematischen Methoden zur Qualitätskontrolle von Emissionsdaten aus Kammermessungen deutlich. Aufgrund dessen wurde ein achtstufiges Daten-Qualitäts-Management-System entwickelt, welches auf objektiven Kriterien basiert und die Datenzuverlässigkeit, ebenso wie die Datenakzeptanzrate verbessert. Die qualitätsgeprüften Ergebnisse dieser Studie bestätigten, dass Landnutzungsänderungen einen signifikanten Einfluss auf THG-Emissionen haben. Die ermittelten Emissionswerte zeigten eine deutliche Erhöhung des Treibhausgaspotentials nach der Umwandlung von natürlichen Feuchtgebieten zu Ackerland. Außerdem ergab diese Studie, dass intensive Anbaumethoden mit hohem Ertragspotential nicht zu signifikant erhöhten ertrags-basierten TGH-Emissionen führten. Die berechneten Treibhausgaspotential-Indizes intensiver Anbaumethoden mit Düngereinsatz zeigten gleich hohe oder sogar geringere Werte verglichen mit ungedüngten Anbaumethoden. Intensive Anbaumethoden mit hohen Erträgen stellen somit einen möglichen Kompromiss zwischen Nahrungsmittelanbau und THG-Emissionen dar. Für eine Minderung der THG-Emissionen ist es allerdings zwingend notwendig, natürliche Feuchtgebietsflächen anderorts zu schonen und in ihrem natürlichen Zustand zu belassen
"Are they crazy?": social representations, conformism, and behavior
This is a commentary on certain aspects of norm theory in terms of social representation theory. The aspects are the issue of conformism versus nonconformism, semantic grounding of norms, and change and transmission. It refers to some of the articles collected in the special issue on Advances in Intersubjective Norm Research
Blockchain Vending Machine: A Smart Contract-Based Peer-to-Peer Marketplace for Physical Goods
In this paper, we propose an autonomous vending machine that is governed by a public Blockchain and smart contracts platform. Set up as a decentralized autonomous organization, it serves as an open marketplace for physical goods, where anyone can buy and/or sell objects. We propose a basic architecture for the machine, analyze pricing and fee mechanisms and examine potential pitfalls. Moreover, we discuss open issues, possible extensions and further areas for improvement. We conclude that the deployment of such machines could significantly improve our understanding of decentralized autonomous organizations and build a bridge between virtual and physical markets. Insights gained from such an experiment may raise important questions for further researc
Compliant 3D Hydrogel Bead Scaffolds to Study Cell Migration and Mechanosensitivity in vitro
Gewebe sind nicht nur durch ihre biochemische Zusammensetzung definiert, sondern auch durch ihre individuellen mechanischen Eigenschaften. Inzwischen ist es weithin akzeptiert, dass Zellen ihre mechanische Umgebung spüren und darauf reagieren. Zum Beispiel werden Zellmigration und die Differenzierung von Stammzellen durch die Umgebungssteifigkeit beeinflusst. Um diese Effekte in vitro zu untersuchen, wurden viele Zellkulturstudien auf 2D Hydrogelsubstraten durchgeführt. Zusätzlich dazu steigt die Anzahl von Studien an, die hydrogelbasierte 3D-Scaffolds nutzen, um 2D Studien zu validieren und die experimentellen Bedingungen der Situation in vivo anzunähern. Jedoch erweist es sich weiterhin als schwierig den Effekt von Mechanik in 3D in vitro zu untersuchen, da in den gemeinhin genutzten 3D Hydrogelsystemen immer eine Kopplung zwischen Gelporosität und Steifigkeit besteht. Zusätzlich hängt die Konzentration der biologisch aktiven Bindungsstellen für Zellen oft ebenfalls von der Steifigkeit ab.
Diese Arbeit präsentiert die Entwicklung und Optimierung neuer 3D Hydrogelkugel-Scaffolds, in denen die Steifigkeit von der Porosität schließlich entkoppelt wird. Mit Hydrogelkugeln als Scaffold-Bausteine ist es nun möglich 3D Scaffolds mit definierten mechanischen Eigenschaften und konstanter Porengröße zu generieren. Während der Methodenentwicklung wurden verschiedene Prinzipien und Kultivierungskammern konstruiert und überarbeitet, gefolgt von der theoretischen Betrachtung der Sauerstoffdiffusion, um die
Eignung der gewählten Kammer hinsichtlich Zellvitalität und Zellwachstum zu überprüfen. Eine Kombination aus mehreren getesteten Filtern wurde ausgewählt um HydrogelkugelScaffolds erfolgreich in der ausgewählten Kammer zu generieren. Im Weiteren wurden verschiedene Hydrogelmaterialien untersucht hinsichtlich der erfolgreichen Produktion monodisperser Hydrogelkugeln und der Erzeugung stabiler Scaffolds. Hydrogelkugeln aus Polyacrylamid (PAAm) wurden als Scaffold-Bausteine ausgewählt um damit die Eignung des entwickelten Systems zu demonstrieren lebende Zellen zu mikroskopieren. Außerdem wurde
das Überleben von Fibroblasten über vier Tage in unterschiedlich steifen HydrogelkugelScaffolds erfolgreich gezeigt. Weiterhin war es möglich erste Zellmigrationsexperimente durchzuführen. Dafür wurden sowohl einfache PAAm-Hydrogelkugeln als auch mit Adhäsionsmolekülen funktionalisierte Hydrogelkugeln genutzt, um unterschiedlich steife Schichten in einem Scaffold zu erzeugen. Dadurch war es möglich nicht nur Zellmigration anhand von Zelladhäsion in 3D Scaffolds mit Steifigkeitsgradienten zu beobachten, sondern auch Zellmigration ohne Zelladhäsion.:1 Introduction
1.1 Mechanics play a role in biology
1.2 3D cultures and scaffolds
1.3 3D hydrogel systems to study effects of mechanics
1.4 Decoupling stiffness and porosity in 3D scaffolds
2 Materials
3 Methods
3.1 Laser scanning microscopy and microscopy data processing
3.2 Atomic force microscopy (AFM)
3.3 Refractive index matching of PMMA beads
3.4 Regular PMMA bead scaffolds for developing analysis algorithm
3.5 Cell culture standards
3.6 Fluorescent labelling of ULGP agarose
3.7 Production of polydisperse ULGP agarose beads
3.8 Hydrogel bead production via microfluidics
3.9 PAAm bead functionalization
3.10 Real-time fluorescence and deformability cytometry (RT-fDC)
3.11 3D scaffolds made from hydrogel beads
3.12 Statistics
4 Results
4.1 Design of a suitable scaffold device
4.2 Theoretical oxygen supply in 3D culture system is sufficient for cell survival and proliferation
4.3 Further optimization of 3D scaffold device
4.3.1 PMMA beads can be arranged in stable scaffolds
4.3.2 Regular PMMA bead scaffolds can be achieved and analysed
4.3.3 PMMA bead scaffolds and agarose bead scaffolds act as combined filter to stack up hydrogel beads
4.4 PAAm hydrogel beads produced by microfluidics are suitable to create compliant 3D scaffolds
4.5 Reproducible, regular and stable 3D scaffolds made of hydrogel beads
4.6 NIH-3T3/GFP cell migration within 3D hydrogel bead scaffolds
5 Discussion and Concluding Remarks
6 Bibliography
List of Figures
List of Tables
Eigenständigkeitserklärung
Appendix A
Appendix B
FIJI macro for FFT analysis maxima
Python script to determine regularity of PMMA bead scaffolds
Excel macro to determine number of peaks for regularity analysisTissues are defined not only by their biochemical composition, but also by their distinct mechanical properties. It is now widely accepted that cells sense their mechanical environment and respond to it. For example, cell migration and stem cell differentiation is affected by stiffness. To study these effects in vitro, many cell culture studies have been performed on 2D hydrogel substrates. Additionally, the amount of 3D studies based on hydrogels as 3D scaffold is increasing to validate 2D in vitro studies and adjust experimental conditions closer to the situation in vivo. However, studying the effects of mechanics in vitro in 3D is still challenging as commonly used 3D hydrogel assays always link gel porosity with stiffness. Additionally, the concentration of biologically active adhesion sides often also
depends on the stiffness.
This work presents the development and optimization of novel 3D hydrogel bead scaffolds where the stiffness is finally decoupled from porosity. With hydrogel beads as scaffold building blocks it was possible to generate 3D scaffolds with defined mechanical properties and a constant pore size. During the method development, different culture devices were constructed and revised, followed by oxygen diffusion simulations to proof the suitability of the chosen device for cell survival and growth. A combination of different filter approaches was selected to generate hydrogel bead scaffolds in the culture device. Furthermore, different
hydrogel materials were investigated regarding successful production of monodisperse beads and stable scaffold generation. Polyacrylamide (PAAm) hydrogel beads were chosen as scaffold building blocks to demonstrate live-cell imaging and successful cell survival over four days in differently compliant hydrogel bead scaffolds. Moreover, first cell migration experiments were performed by using plain PAAm hydrogel beads as well as PAAm hydrogel beads functionalized with adhesion molecules with differently stiff layers in one scaffold. Thereby fibroblast migration was observed not only in adhesion-dependent migration manner, but also in an adhesion-independent mode .:1 Introduction
1.1 Mechanics play a role in biology
1.2 3D cultures and scaffolds
1.3 3D hydrogel systems to study effects of mechanics
1.4 Decoupling stiffness and porosity in 3D scaffolds
2 Materials
3 Methods
3.1 Laser scanning microscopy and microscopy data processing
3.2 Atomic force microscopy (AFM)
3.3 Refractive index matching of PMMA beads
3.4 Regular PMMA bead scaffolds for developing analysis algorithm
3.5 Cell culture standards
3.6 Fluorescent labelling of ULGP agarose
3.7 Production of polydisperse ULGP agarose beads
3.8 Hydrogel bead production via microfluidics
3.9 PAAm bead functionalization
3.10 Real-time fluorescence and deformability cytometry (RT-fDC)
3.11 3D scaffolds made from hydrogel beads
3.12 Statistics
4 Results
4.1 Design of a suitable scaffold device
4.2 Theoretical oxygen supply in 3D culture system is sufficient for cell survival and proliferation
4.3 Further optimization of 3D scaffold device
4.3.1 PMMA beads can be arranged in stable scaffolds
4.3.2 Regular PMMA bead scaffolds can be achieved and analysed
4.3.3 PMMA bead scaffolds and agarose bead scaffolds act as combined filter to stack up hydrogel beads
4.4 PAAm hydrogel beads produced by microfluidics are suitable to create compliant 3D scaffolds
4.5 Reproducible, regular and stable 3D scaffolds made of hydrogel beads
4.6 NIH-3T3/GFP cell migration within 3D hydrogel bead scaffolds
5 Discussion and Concluding Remarks
6 Bibliography
List of Figures
List of Tables
Eigenständigkeitserklärung
Appendix A
Appendix B
FIJI macro for FFT analysis maxima
Python script to determine regularity of PMMA bead scaffolds
Excel macro to determine number of peaks for regularity analysi
Compliant 3D Hydrogel Bead Scaffolds to Study Cell Migration and Mechanosensitivity in vitro
Gewebe sind nicht nur durch ihre biochemische Zusammensetzung definiert, sondern auch durch ihre individuellen mechanischen Eigenschaften. Inzwischen ist es weithin akzeptiert, dass Zellen ihre mechanische Umgebung spüren und darauf reagieren. Zum Beispiel werden Zellmigration und die Differenzierung von Stammzellen durch die Umgebungssteifigkeit beeinflusst. Um diese Effekte in vitro zu untersuchen, wurden viele Zellkulturstudien auf 2D Hydrogelsubstraten durchgeführt. Zusätzlich dazu steigt die Anzahl von Studien an, die hydrogelbasierte 3D-Scaffolds nutzen, um 2D Studien zu validieren und die experimentellen Bedingungen der Situation in vivo anzunähern. Jedoch erweist es sich weiterhin als schwierig den Effekt von Mechanik in 3D in vitro zu untersuchen, da in den gemeinhin genutzten 3D Hydrogelsystemen immer eine Kopplung zwischen Gelporosität und Steifigkeit besteht. Zusätzlich hängt die Konzentration der biologisch aktiven Bindungsstellen für Zellen oft ebenfalls von der Steifigkeit ab.
Diese Arbeit präsentiert die Entwicklung und Optimierung neuer 3D Hydrogelkugel-Scaffolds, in denen die Steifigkeit von der Porosität schließlich entkoppelt wird. Mit Hydrogelkugeln als Scaffold-Bausteine ist es nun möglich 3D Scaffolds mit definierten mechanischen Eigenschaften und konstanter Porengröße zu generieren. Während der Methodenentwicklung wurden verschiedene Prinzipien und Kultivierungskammern konstruiert und überarbeitet, gefolgt von der theoretischen Betrachtung der Sauerstoffdiffusion, um die
Eignung der gewählten Kammer hinsichtlich Zellvitalität und Zellwachstum zu überprüfen. Eine Kombination aus mehreren getesteten Filtern wurde ausgewählt um HydrogelkugelScaffolds erfolgreich in der ausgewählten Kammer zu generieren. Im Weiteren wurden verschiedene Hydrogelmaterialien untersucht hinsichtlich der erfolgreichen Produktion monodisperser Hydrogelkugeln und der Erzeugung stabiler Scaffolds. Hydrogelkugeln aus Polyacrylamid (PAAm) wurden als Scaffold-Bausteine ausgewählt um damit die Eignung des entwickelten Systems zu demonstrieren lebende Zellen zu mikroskopieren. Außerdem wurde
das Überleben von Fibroblasten über vier Tage in unterschiedlich steifen HydrogelkugelScaffolds erfolgreich gezeigt. Weiterhin war es möglich erste Zellmigrationsexperimente durchzuführen. Dafür wurden sowohl einfache PAAm-Hydrogelkugeln als auch mit Adhäsionsmolekülen funktionalisierte Hydrogelkugeln genutzt, um unterschiedlich steife Schichten in einem Scaffold zu erzeugen. Dadurch war es möglich nicht nur Zellmigration anhand von Zelladhäsion in 3D Scaffolds mit Steifigkeitsgradienten zu beobachten, sondern auch Zellmigration ohne Zelladhäsion.:1 Introduction
1.1 Mechanics play a role in biology
1.2 3D cultures and scaffolds
1.3 3D hydrogel systems to study effects of mechanics
1.4 Decoupling stiffness and porosity in 3D scaffolds
2 Materials
3 Methods
3.1 Laser scanning microscopy and microscopy data processing
3.2 Atomic force microscopy (AFM)
3.3 Refractive index matching of PMMA beads
3.4 Regular PMMA bead scaffolds for developing analysis algorithm
3.5 Cell culture standards
3.6 Fluorescent labelling of ULGP agarose
3.7 Production of polydisperse ULGP agarose beads
3.8 Hydrogel bead production via microfluidics
3.9 PAAm bead functionalization
3.10 Real-time fluorescence and deformability cytometry (RT-fDC)
3.11 3D scaffolds made from hydrogel beads
3.12 Statistics
4 Results
4.1 Design of a suitable scaffold device
4.2 Theoretical oxygen supply in 3D culture system is sufficient for cell survival and proliferation
4.3 Further optimization of 3D scaffold device
4.3.1 PMMA beads can be arranged in stable scaffolds
4.3.2 Regular PMMA bead scaffolds can be achieved and analysed
4.3.3 PMMA bead scaffolds and agarose bead scaffolds act as combined filter to stack up hydrogel beads
4.4 PAAm hydrogel beads produced by microfluidics are suitable to create compliant 3D scaffolds
4.5 Reproducible, regular and stable 3D scaffolds made of hydrogel beads
4.6 NIH-3T3/GFP cell migration within 3D hydrogel bead scaffolds
5 Discussion and Concluding Remarks
6 Bibliography
List of Figures
List of Tables
Eigenständigkeitserklärung
Appendix A
Appendix B
FIJI macro for FFT analysis maxima
Python script to determine regularity of PMMA bead scaffolds
Excel macro to determine number of peaks for regularity analysisTissues are defined not only by their biochemical composition, but also by their distinct mechanical properties. It is now widely accepted that cells sense their mechanical environment and respond to it. For example, cell migration and stem cell differentiation is affected by stiffness. To study these effects in vitro, many cell culture studies have been performed on 2D hydrogel substrates. Additionally, the amount of 3D studies based on hydrogels as 3D scaffold is increasing to validate 2D in vitro studies and adjust experimental conditions closer to the situation in vivo. However, studying the effects of mechanics in vitro in 3D is still challenging as commonly used 3D hydrogel assays always link gel porosity with stiffness. Additionally, the concentration of biologically active adhesion sides often also
depends on the stiffness.
This work presents the development and optimization of novel 3D hydrogel bead scaffolds where the stiffness is finally decoupled from porosity. With hydrogel beads as scaffold building blocks it was possible to generate 3D scaffolds with defined mechanical properties and a constant pore size. During the method development, different culture devices were constructed and revised, followed by oxygen diffusion simulations to proof the suitability of the chosen device for cell survival and growth. A combination of different filter approaches was selected to generate hydrogel bead scaffolds in the culture device. Furthermore, different
hydrogel materials were investigated regarding successful production of monodisperse beads and stable scaffold generation. Polyacrylamide (PAAm) hydrogel beads were chosen as scaffold building blocks to demonstrate live-cell imaging and successful cell survival over four days in differently compliant hydrogel bead scaffolds. Moreover, first cell migration experiments were performed by using plain PAAm hydrogel beads as well as PAAm hydrogel beads functionalized with adhesion molecules with differently stiff layers in one scaffold. Thereby fibroblast migration was observed not only in adhesion-dependent migration manner, but also in an adhesion-independent mode .:1 Introduction
1.1 Mechanics play a role in biology
1.2 3D cultures and scaffolds
1.3 3D hydrogel systems to study effects of mechanics
1.4 Decoupling stiffness and porosity in 3D scaffolds
2 Materials
3 Methods
3.1 Laser scanning microscopy and microscopy data processing
3.2 Atomic force microscopy (AFM)
3.3 Refractive index matching of PMMA beads
3.4 Regular PMMA bead scaffolds for developing analysis algorithm
3.5 Cell culture standards
3.6 Fluorescent labelling of ULGP agarose
3.7 Production of polydisperse ULGP agarose beads
3.8 Hydrogel bead production via microfluidics
3.9 PAAm bead functionalization
3.10 Real-time fluorescence and deformability cytometry (RT-fDC)
3.11 3D scaffolds made from hydrogel beads
3.12 Statistics
4 Results
4.1 Design of a suitable scaffold device
4.2 Theoretical oxygen supply in 3D culture system is sufficient for cell survival and proliferation
4.3 Further optimization of 3D scaffold device
4.3.1 PMMA beads can be arranged in stable scaffolds
4.3.2 Regular PMMA bead scaffolds can be achieved and analysed
4.3.3 PMMA bead scaffolds and agarose bead scaffolds act as combined filter to stack up hydrogel beads
4.4 PAAm hydrogel beads produced by microfluidics are suitable to create compliant 3D scaffolds
4.5 Reproducible, regular and stable 3D scaffolds made of hydrogel beads
4.6 NIH-3T3/GFP cell migration within 3D hydrogel bead scaffolds
5 Discussion and Concluding Remarks
6 Bibliography
List of Figures
List of Tables
Eigenständigkeitserklärung
Appendix A
Appendix B
FIJI macro for FFT analysis maxima
Python script to determine regularity of PMMA bead scaffolds
Excel macro to determine number of peaks for regularity analysi
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