Browsing by Author "Nguyen, Hoang"

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Design, assembly and characterization of highly curved DNA origami structures
(2019-01-28) Nguyen, Hoang
Kemian tekniikan korkeakoulu | Master's thesis
DNA origami technique has found application in building nanoscale structures of various complexity and shape, including 3D curvatures with diameters as small as 25 nm, which opens up new venue of research including mimicking cellular components like nuclear pore complex. However, currently there is no concrete guideline available to build such 3D structures and researchers have to rely on an iterative design approach. Moreover, available curvatures in literature were all implemented based on a single type of helix packing, indicating certain difficulty in assemble curvature with the more densely packed square-lattice. In this thesis, a set of principles previously described for curved single-layer structures were adapted for multilayer designs and validated with three structures different in cross-section, torsional rigidity, and dimension. The folding quality and structural integrity of each were characterized with gel electrophoresis and transmission electron microscopy. Comparison among three structures prove the improvement in building curvatures using the proposed principles and suggest the importance of torsional rigidity in designing curvatures. The effort to assemble a square-lattice-based structure meets limited success yet could be improved with further iterations.
End-to-end testing on Web Experience Management Platform
(2020-05-19) Nguyen, Hoang
Perustieteiden korkeakoulu | Master's thesis
End-to-end testing (E2E) is the highest level of testing that verifies the entire system under test. Because tests of this kind are very expensive to develop and execute, they are often automated and used only to test critical functionalities of the system. Despite the abundance of non-academic resources, literature content on this topic is still lacking. Web Experience Management System (WEMP) is a new solution for developing website functionality, where the consultancy company injecting their script di- rectly into customer websites. While providing the flexibility, this also introduces new challenges since development work by customer will not be tested during con- sultancy workflow and vice-versa. Including E2E testing in the current process could help to guard against those misalignment. The goal of this thesis is to implement an automated E2E testing into the current pipeline of an WEMP. The work consists of finding requirements for the needed artifacts and evaluating the result. The process is based on design science research where the artefact is the integration of E2E testing into the pipeline according to the requirements of a case client project. The result of the project is the automated E2E testing pipeline with integrated Continuous Integration (CI), Continuous Delivery (CD) and monitoring setup required for the case project. The result conforms with the preliminary study on E2E testing. It showed how expensive and fragile E2E tests are. In conclusion, E2E tests are helpful but they should be limited to the most crucial customer journey. Moreover, tests should be implemented so that execution and reporting practices are useful for developers.
Exploring the potential of the dip-coating process to control assembly of virus-based nanomaterials thin films on the substrate surfaces
(2021-08-24) Ahlstedt, Jenni
Kemian tekniikan korkeakoulu | Master's thesis
The motivation for this thesis was the concern for the depletion of natural resources and the desire to find more responsible solutions for the development of new biomaterials. Plant viruses have attracted interest due to their safety and diverse structures. They serve as ideal platforms and building blocks for the creation of new nanomaterials. Dip-coating is a cost-effective and facile way to create nanomaterial thin films, however, the effect of the parameters to fully exploit the full potential of the coating process is not yet known. The aim of this work was to gain an understanding of potato virus A (PVA) thin film structures prepared by dip-coating, as previous research data on this cannot be found in the literature. In order to achieve the objectives of the work and to solve the research problems, potato virus A solutions prepared at the University of Helsinki were used in the study. The parameters to be studied in the coating process are the surface charge of the substrate, the effect of solution concentration and pH, as well as the different withdraw rates of the dip-coating. The structures of the resulting coatings were analysed with a Scanning Electron Microscope (SEM), an optical microscope, and an Atomic Force Microscope (AFM). The set objectives of the work were achieved, and the work showed the effect of different parameters on the structures and particle ordering of different PVA films obtained by dip-coating. Thus, the thesis provided a lot of new and interesting information about potato virus A nanomaterials made by dip-coating, which can be considered as very potential building blocks for various engineering applications. In addition, the work provided many reasons for further research to elucidate various findings.
Fabrication of porous hierarchical multilevel composite thin films by combining different self-assembly processes
(2020-10-20) Mader, Ariane
Kemian tekniikan korkeakoulu | Master's thesis
In nature, directed self-assembly on multiple length scales is commonly used to create superior structural and functional materials. Such control over different levels of patterning would also be of great interest for many advanced devices. By now, it remains challenging to fabricate such hierarchical structures. The spontaneous self-organization of block copolymers can further be used as a bottom-up self-assembly technique creating patterns with a 10-100 nm period. The formed pattern can be used to organize nanoparticles. Another self-assembly technique is the condensation of water onto drying polymer films, which can lead to highly ordered honeycomb like patterns, called breath figures, with pores of up to 20 µm in diameter. The pores can be utilized to selectively incorporate nanoparticles into the film. The combination of block copolymer (BCP) assembly and breath figure formation with the incorporation of different nanoparticles into the respective patterns should lead to a multi-hierarchical composite material allowing for unique property combinations and the independent tunability of each level of hierarchy. Using dip-coating for film formation will also allow to create such patterns on an industrial scale. In this thesis, an extensive literature review of the relevant mechanisms is presented. Polymer thin films were created via dip-coating and the complexity of the system increased stepwise. Poly(styrene) was chosen as preliminary cheap model polymer. Breath figures were induced by dispersing water droplets containing sucrose in the solution. Solution and synthesis parameters were optimized, and small ordered pores were mainly found at the bottom of the substrates, among some bigger ones. TiO2 nanoparticles were successfully introduced to assemble at the pores. Replacing poly(styrene) with poly(styrene)-block-poly(4-vinylpyridine) lead to multi-level polymer patterns, with breath figure induced micropores of 1-50 µm diameter, and BCP induced nanopores of 10-80 nm between. The nanoparticles presumably dissolved in the poly(4-vinylpyridine) block. Future directions of this research are discussed, including the continuation with a second type of nanoparticle to reach the desired organisation of different nanoparticles at different length scales.
Ladle furnace slag as a partial binder replacement in floor screeds
(2021-01-25) Akhondzada, Ali
Insinööritieteiden korkeakoulu | Master's thesis