Search results for "materiaalit"
showing 10 items of 102 documents
The effect of steric hindrance on the packing of elongated objects
2016
Fibres of various materials can be deposited to form planar mats of fibres. These kinds of structures have gained substantial attention owing to their direct relation to both large industrial fields, such as paper and nonwovens, and biological structures, such as natural networks of fibrin, actin and collagen. In addition, similar structures are important in new emerging fields such as flexible electronics and tissue engineering. The physical properties of these structures are directly related to the connectivity of the network, thus a thorough understanding of the contact formation of the system is of great importance from both a scientific viewpoint as well as for its application in the e…
Kaliksareeneilla päällystetyt kultananopartikkelit
2011
Pro gradu -tutkielmassa kerrotaan, mitä tällä hetkellä tiedetään kaliksareeneilla päällystettyjen kultananopartikkeleiden rakenteesta. Lisäksi käsitellään partikkelien valmistusta joko suorilla menetelmillä tai valmiisiin kultananopartikkeleihin tehdyllä ligandinvaihdolla ja kerrotaan valmistettujen partikkelien karakterisointimenetelmistä. Tutkielmassa perehdytään myös kaliksareeneilla päällystettyjen kultananopartikkelien sovelluksiin materiaalitieteissä, tunnistuksessa ja havaitsemisessa, katalyysissä ja sitoutumisessa biologisiin rakenteisiin. Kokeellisessa osassa pyrittiin valmistamaan resorsinareeneja, pyrogallareeneja ja kultananopartikkeleita ligandinvaihtoa varten.
Fast pyrolysis of hot-water-extracted and delignified Norway spruce (Picea abies) sawdust by Py-GC/MS
2019
The thermochemical behavior of Norway spruce (Picea abies) sawdust as such and after various chemical treatments (hot-water extraction, delignification, and hot-water extraction followed by delignification) was investigated by analytical pyrolysis–gas chromatography–mass spectrometry. In each case, the yields of major GC-amenable condensable products were semi-quantitatively measured, and the individual compounds were classified into several compound groups. The formation of these groups from feedstock samples with varying mass portions of their structural constituents (carbohydrates and lignin) was determined at 500 °C and 700 °C with a residence time of 5 s and 20 s. The formation of pyro…
X-Ray Nanotomography of Individual Pulp Fibre Bonds Reveals the Effect of Wall Thickness on Contact Area
2019
Fibre bonds play an essential role in various properties of paper. Much research has focused on their strength, but the determination of the actual contact area also provides a challenge. Many of the research methods rely on optical tools, which are restricted by the wavelength of light that is utilised. Novel X-ray computed tomography devices utilise X-rays in studying the inner structure of materials, and surpass the optical methods in terms of resolution, allowing detection of even smaller details and variations in distance between the fibres in the bond intersection area. X-ray nanotomography was used to image 26 individual cellulose fibre bonds made of springwood and summerwood fibres …
Why open educational resources repositories fail : the contribution of quality approaches to the success of repositories
2016
Over the last two decades, millions of Open Educational Resources (OER) have become freely available for teachers and learners online. These resources are usually accessible through Learning Object Repositories (LORs), which are databases with a user interface. LORs are rarely used to their full potential and often considered as ‘failures’. Previous studies have shown that quality has a critical role in the success of information systems such as LORs. However there are no common guidelines for quality assurance approaches for LORs, nor are there studies into the contribution made by different LOR quality assurance approaches to the success of a repository. Measuring quality and success have…
Fabrication of DNA origami lattice on silicon surface for DNA-assisted lithography
2022
Metamaterials obtain new properties from having metallized nanoscale features that are often arranged in repeating patterns. In particular, there is a need to create metasurfaces with a negative refractive index. As nanoscale fabrication using conventional top-down methods can be both difficult and time-consuming, bottom-up techniques have gained growing interest. Especially, the DNA origami method can be utilized to assemble lattices with nanoscale features on 2D surfaces, which can then be metallized using DNA-assisted lithography (DALI). This thesis provides a full study of the DNA origami fishnet lattice assembly kinetics and optimization of lattice order on a silicon surface using liqu…
DESIGN PRINCIPLES OF COLLABORATIVE LEARNING SPACE CONNECTING TEACHERS AND REFUGEE CHILDREN - A DESIGN SCIENCE RESEARCH STUDY
2020
Learning the German language is one of the most critical challenges for refugee children in Germany. It is a prerequisite to allow communication and integration into the educational system. To solve the underlying problem, we conceptualized a set of principles for the design of language learning systems to support collaboration between teachers and refugee children, using a Design Science Research approach. The proposed design principles offer functional and non-functional requirements of systems, including the integration of open educational resources, different media types to develop visual and audio narratives that can be linked to the cultural and social background. This study also illu…
Beach volley koululiikuntamuotona
1999
Effects of Lithium Source and Content on the Properties of Li-Rich Layered Oxide Cathode Materials
2023
Lithium-rich layered oxide (LLO) are considered high-capacity cathode materials for next-generation lithium-ion batteries. In this study, LLO cathode materials were synthesized via the hydroxide coprecipitation method followed by a two-step lithiation process using different lithium contents and lithium sources. The effects of lithium content and lithium source on structure and electrochemical performance were investigated. This study demonstrated the clear impact of Li/TM ratio on electrochemical performance. Lower Li/TM ratio reduced the irreversible capacity loss in the first cycle and provided better cycling stability among all samples. The best results exhibited an initial discharge ca…