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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
231

Friction and adhesion mediated by supramolecular host–guest complexes

Guerra, Roberto, Benassi, Andrea, Vanossi, Andrea, Ma, Ming, Urbakh, Michael 13 January 2020 (has links)
The adhesive and frictional response of an AFM tip connected to a substrate through supramolecular host–guest complexes is investigated by dynamic Monte Carlo simulations. Here, the variation of the pull-off force with the unloading rate recently observed in experiments is unraveled by evidencing simultaneous (progressive) breaking of the bonds at fast (slow) rates. The model reveals the origin of the observed plateaus in the retraction force as a function of the tip-surface distance, showing that they result from the tip geometrical features. In lateral sliding, the model exhibits a wide range of dynamic behaviors ranging from smooth sliding to stick-slip at different velocities, with the average friction force determined by the characteristic formation/rupture rates of the complexes. In particular, it is shown that for some molecular complexes friction can become almost constant over a wide range of velocities. Also, we show the possibility of exploiting the ageing effect through slide-hold-slide experiments, in order to infer the characteristic formation rate. Finally, our model predicts a novel ‘‘antiageing’’ effect which is characterized by a decrease of the static friction force with the hold time. Such an effect is explained in terms of enhancement of adhesion during sliding, especially observed at high driving velocities.
232

Multifunctional and Stimuli-Responsive Polymersomes for Biomedical Applications

Iyisan, Banu 18 November 2016 (has links)
The demand for multifunctional nanocontainers possessing both recognition ability and responsive nature is increasing greatly because of their high potential in various biomedical applications. The engineering of such smart nanovesicles is useful to enhance the efficiency of many therapeutic and diagnostic tools that have the applicability in targeted drug delivery systems as well as designing sensing devices or conducting selective reactions as nanoreactors in the scope of nanobiotechnology. For this purpose, this study demonstrates the formation of multifunctional and stimuli-responsive polymersomes comprising various abilities including pH and light sensitivity as well as many reactive groups with sufficient accessibility to be used as smart and recognitive nanocontainers. The fabrication included several steps starting from the synthesis of azide and adamantane terminated block copolymers, which were then self-assembled to prepare the polymersomes with the corresponding functional groups for the subsequent post-conjugations at the vesicle periphery. The accessible and sufficiently reactive groups were quantitatively proven when UV and IR cleavable NVOC protected amino groups as well as β-cyclodextrin molecules were conjugated to the pre-formed polymersomes through click chemistry and strong host-guest complexations. The gained light responsivity with the aid of successful NVOC attachment enabled further selective photochemical reactions triggered either by UV or NIR light leading to liberated amine groups on the polymersome surface. Therein, these released amino groups were further conjugated with a model fluorescent compound as mimicking the attachment of biorecognition elements to see the direct picture of the applicability. To realize this concept in a more localized and selective way as well as to avoid the possible side effects of UV light, the NIR-light induced photochemical reactions and further dye coupling were performed when polymersomes were immobilized onto solid substrates. This fixation was achieved by adapting the host-guest chemistry into this part and conjugating the adamantane decorated polymersomes onto β-cyclodextrin coated substrates. Several investigations including adhesion behavior, pH sensitivity and mechanical properties of the established multifunctional polymersomes under liquid phase have been performed. It has been found that the polymersome shape is highly dependent on the attractive forces of the substrate and needs to be optimized to avoid the flattening of the vesicles. For these optimization steps, different conditions were investigated including the decrease of cyclodextrin amount and additional surface passivation with PEG molecules on the solid substrates. Besides, the calculated Young’s and bending modulus of the polymersome membrane from AFM measurements showed a robust but still flexible “breathable” membrane which is an important criterion for the applicability of these smart and stable vesicles. In addition, the hosting ability as well as diffusion limits and sufficient membrane permeability of the polymersomes were observed by encapsulating gold nanoparticles as a smart cargo and doxorubicin molecules as an anticancer drug. In conclusion, the established multifunctional polymersomes are highly versatile and thus present new opportunities in the design of targeted and selective recognition systems which is highly interesting for various applications including development of microsystem devices, design of chemo/biosensors, and also for conducting enhanced, combined therapy in the field of drug delivery.
233

Stejné, ale jiné? Srovnání integrační zkušenosti uprchlíků a gastarbeiterů v Německu / Same, but different? A comparison of the integration experiences of refugees and guest worker migrants in Germany

Gundacker, Lidwina January 2018 (has links)
Same, but different? A comparison of the integration experiences of refugees and guest worker migrants in Germany Abstract The increasing number of asylum seekers arriving in Germany over the past years have not only sparked an emotional public debate on immigration and societal membership, but have also proven to be a major challenge for policy-makers. Although the volume of refugee migration is indeed unprecedented in Germany, the country has had significant experience with receiving and integrating newcomers in its recent past: the post-war economic boom has led to the recruitment of millions of foreign workers, so- called Gastarbeiter. A non-negligible share ultimately settled permanently, but their integration process was not without its challenges. This paper argues that Germany's guest worker experience offers valuable insight into current integration processes in the German context. To make this existing knowledge accessible, this work uses a historical approach to identify the main elements that have shaped the integration experiences of guest workers in Germany, tied in with an econometric examination assessing the main factors in turn associated with the economic integration of the current refugee cohort. Comparison of the results suggest that a range of obstacles faced by guest workers and their...
234

Úrazovost ve florbale v mužské nejvyšší soutěži v letech 2014-2019 / The incidency of injury among men players in the highest floorball league during years 2014-2019

Honzová, Petra January 2020 (has links)
The topic of this diploma thesis is the description of injury rate at floorball in the men's highest competition within the years 2014-2019. The work consists of theoretical and practical part. The rules of floorball, the popularity, and unions (federations) of this sport in our country and abroad, the concept of the season and the characteristics of the player's movement, including muscle imbalances are described in the theoretical part. A general division of sports injuries and a description of the most common injuries at floorball is a part of theory, as well as their prevention, registration, and treatment. In addition to contact with another person, glasses, shoes, the surface, the age of the player and, in the case of goalkeepers, knee protectors can influence injuries at this indoor sport. Further the method of educating coaches in the Czech Republic and the content of a seminar on compensation, which is presented to coaches at trainings, is also described there. The practical part is focused on the collection of injury rate data from paper and electronic records from matches in the seasons from 2014/2015 to 2018/2019. These results are compared with respect to the presence of a physiotherapist, the player's age, the surface in the halls, the phase of the season and the occurrence of an...
235

Birch leaf carbon dots: characterization and application in a light-emitting electrochemical cell

Gregorsson, Märta January 2022 (has links)
A new rising star in the carbon nanomaterial family is carbon dots. Carbon dots have received great attention due to their excellent luminescence and low toxicity. In this project, a new carbon dot derived from birch leaves is studied and characterized. The birch leaf carbon dot (BL-CD) exhibits narrow red photoluminescence (peak = 670 nm, full width at half maximum = 23 nm) with a photoluminescence quantum yield of 26% in dilute methanol solution.  The presence of the characteristic peaks of the pigment pheophytin-a in the absorption spectrum and the photoluminescence spectrum of the BL-CD and the absence of a crystal structure together with the narrow and excitation-independent photoluminescence indicate a carbon dot with a non-emissive amorphous structure with emissive molecular sites consisting of the pigment. The photoluminescence quenching of the BL-CDs in solid-state is reduced by the introduction of a hostmaterial. The use of a host enabled the employment of BL-CDs as the emitter in a light-emitting electrochemical cell (LEC). This project paves the way for further development of the environmentally friendly and sustainable BL-CD LEC.
236

Water-Mediated Interactions Through the Lens of Raman Multivariate Curve Resolution

Denilson Mendes de Oliveira (10708623) 06 May 2021 (has links)
Raman multivariate curve resolution (Raman-MCR) spectroscopy is used to study water-mediated interactions by decomposing Raman spectra of aqueous solutions into bulk water and solute-correlated (SC) spectral components. The SC spectra are minimum-area difference spectra that reveal solute-induced perturbations of water structure, including changes in water hydrogen-bonding strength, tetrahedral structure, and formation of dangling (non-hydrogen-bonded) OH defects in a solute's hydration shell. Additionally, Raman-active intramolecular vibrational modes of the solute may be used to uncover complementary information regarding solute--solute interactions. Herein, Raman-MCR is applied to address fundamental questions related to: (1) confined cavity water and its connection to host-guest binding, (2) hydrophobic hydration of fluorinated solutes, (3) specific ion effects on nonionic micelle formation, and (4) ion pairing in aqueous solutions.
237

EXPERIMENTAL AND COMPUTATIONAL STUDIES OF HYDROPHOBIC ASSOCIATION AND ION AFFINITY FOR MOLECULAR OIL/WATER INTERFACES

Andres Urbina (12464403) 27 April 2022 (has links)
<p>  </p> <p>Experimental and computational techniques are used to study physico-chemical phenomena occurring in water on which hydrophobic interactions play a role. In particular, hydrophobic self-aggregation, including host-guest binding, and the affinity of ions to oil/water interfaces are investigated. Raman multivariate curve resolution (Raman-MCR) spectroscopy was the experimental technique used to unveil intermolecular interactions through the analysis of solute-correlated (SC) vibrational spectra. Molecular simulations, including molecular dynamics (MD) simulations, quantum-mechanical calculations, or a combination of both, were carried out to assist with the molecular-level interpretation of the experimental SC spectra.</p>
238

DNA-gesteuerte Multivalenz: Untersuchungen zur Reichweite der Bivalenz und Anwendungen in der Assemblierung bi- und multivalenter Peptidkonjugate

Dubel, Natali 01 July 2019 (has links)
Multivalente Wechselwirkungen spielen sowohl in der Natur als auch für die Konstruktion hochaffiner Binder eine wichtige Rolle. In dieser Arbeit wurde die Grenze der Bivalenz in Bezug auf den Bindungsabstand, die monovalente Interaktionsstärke und die Flexibiltät des Gerüsts untersucht. Die Modifizierung von DNA mit Cucurbit[7]uril und zwei verschiedenen Adamantananaloga (Ad1 und Ad2) sowie die Verwendung verschiedener Template, ermöglichte die Konstruktion diverser bivalenter Modellsysteme. Die Ergebnisse zeigten eine Distanzabhängigkeit des bivalenten Effekts, der mit dem Bindungsabstand abnahm. Im Gegensatz zum schwächeren Binder (Ad2), war der stärkere Binder (Ad1) in der Lage auch noch bei großen Abständen von einer bivalenten Verstärkung zu profitieren. Somit besteht eine Abhängigkeit des bivalenten Effekts von der monovalenten Bindungsstärke. Mit diesem System wurde anschließend untersucht, unter welchen Bedingungen bivalente Systeme multimolekulare Strukturen ausbilden. Es konnte gezeigt werden, dass verbrückende Strukturen nur bei hohen Konzentrationen und bei Abwesenheit eines bivalenten Effekts vorliegen können. Im zweiten Teil dieser Arbeit wurde ein bispezifischer Binder auf seine Affinität, Selektivität und auf seinen Einfluss auf die Rezeptoraktivität untersucht. Dafür wurden Oligonukleotide mit Cilengitid, welches αvβ3-Integrin binden kann, und mit einem Peptoid, welches VEGFR2 binden kann, modifiziert. Durch Verwendung verschiedener Template konnten bispezifische Binder mit unterschiedlichen Ligandenabständen konstruiert werden. Messungen an HUVEC-Zellen ergaben eine höhere Affinität der bispezifischen Binder im Vergleich zu den monospezifischen. ELISA-Messungen ergaben eine distanzabhängige Aktivierung oder Deaktivierung der Phosphorylierung von VEGFR2. Es konnte somit ein Modellsystem konstruiert werden, mit dem die Rezeptoraktivität gesteuert werden konnte. / Multivalent interactions play an important role in nature and are also used to construct high-affinity binders. In this work the limit of bivalency based on binding distance, flexibility of the system and monovalent binding-strength was investigated. Modification of DNA with Cucurbit[7]uril (CB[7]) and two adamantane-analogues (Ad1 and Ad2), along with the use of different templates, enabled the construction of diverse bivalent model-systems. The results revealed a distance-dependency of the bivalent effect, which decreased with increasing binding distance. The stronger binder (Ad1) was able to benefit from bivalent enhancement at relatively large binding distances compared to the weaker binder (Ad2). This denotes a dependency of the bivalent effect on the monovalent binding strength. The same system was used to investigate the factors leading to crosslinking. The results show that only at high concentrations, and when the system does not have to compete with a bivalent enhancement, can multimolecular structures be formed. The second part of this work deals with a bispecific binder. Binding affinities, selectivity and the impact of the binder on receptor activity were tested. Accordingly, oligonucleotides were modified with cilengitide, which is able to bind αvβ3-Integrin, and with a bivalent peptoid, which binds to VEGFR2. The use of different DNA templates enabled construction of several bispecific binders with different binding distances. Measurements with HUVEC cells revealed higher affinities of the bispecific binders compared to the monospecific ones. ELISA-measurements demonstrated that activation or deactivation of the VEGFR2-phosphorylation was distance dependent. Consequently, a model system was constructed which was able to control receptor activity.
239

Ubytovací zařízení / Accommodation

Maryšková, Eva January 2022 (has links)
The aim of my thesis is to design new Guest house in Čeladná. First part is focused on building design and construction. Second part is focused on heating, ventilation and air conditioning (HVAC) design and renewable energy sources. Third part is focused on detailed solution of noise and vibration from the environment around building. Guest house is three – storey building but there is one more underground storey for technical facilities. Ground floor contains staff facilities, restaurant, entrance hall with stairs and office. On the second floor we can find four guest rooms with terrace and corridor. On the third floor we can find three guest rooms. Heating in the building is secured by gas condensing boilers. Ventilation is provided by two air condition units. Each guest room has radiators and cooling distribution units and ventilation. Cooling is secured by one cooling unit on the green roof. On the gable roof we can find 75 photovoltaic panels. Third part is focused on detailed solution of noise, vibration from the environment around building and spatial acoustics of guest room. The thesis is carried out in AutoCAD, Sketch up, Lumion and DEKSOFT software. All structures comply with the valid standards and regulation.
240

Penzion U Odry / Guesthouse "U ODry"

Spáčilová, Kristýna January 2022 (has links)
The subject of this diploma thesis is the project documentation of the new building - pension U Odry in Přerov-Kozlovice. Accommodation capacity is 36 people. In the pension there is also restaurant. The building is designed as a three-storey. On the first floor there are rooms for guests entering the accommodation facility, facilities for accommodation, technical facilities of the building and the restaurant, including premises for its operation. There are guest rooms on the second and third floors. The bases are made up of strip foundations. The external loadbearing mansards and partitions are made of YTONG lightweight concrete blocks. The internal loadbearing masonry is made of SILKA lime-sand blocks. The ceiling structure is designed from SPIROLL prestressed concrete floor slab. The roofing of the building is solved using flat vegetation roofs.

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