Search results for "materiaalit"

Instrumentation for time-of-flight elastic recoil detection analysis

2016

Time-of-flight elastic recoil detection is an ion beam based method to analyze the elemental composition of thin film samples at different depths. In order to improve the mass resolution and to enable kinematic correction a position sensitive gas ionization chamber energy detector was constructed. This detector along with pre-existing timing detectors were connected to a modern fully digitizing data acquisition setup. This thesis describes the design of these instruments, including all aspects from the mechanical design of the gas ionization detector to the algorithm and software development of the digitizing acquisition setup. The performance of the system has been studied with measurements …

Measurements on electric breakdown in dielectric barriers between carbon nanotubes and electrodes

2009

Orgaaniset ja metallo-orgaaniset epälineaariset optiset materiaalit

2017

Tässä tutkielmassa on perehdytty kirjallisuudessa raportoituihin orgaanisiin ja metallo-orgaanisiin epälineaarisiin optisiin (NLO) materiaaleihin sekä tutkittu mahdollisuutta valmistaa niitä yksinkertaisista orgaanisista molekyyleistä. Työn kirjallisessa osassa luodaan lyhyt katsaus NLO-teoriaan sekä käydään läpi orgaanisten ja metallo-orgaanisten NLO-yhdisteiden lisäksi erilaisia toisen harmonisen säteilyn (SHG) mittaustekniikoita sekä erilaisia kiteytystekniikoita. Kokeellisessa osuudessa on valmistettu polaarisista molekyyleistä heikoilla vuorovaikutuksilla sitoutuneita yhdisteitä, joista osalla on havaittu olevan SHG-ominaisuuksia.

Eettistä kasvatusta? : laadullinen tutkimus urheilulajiliittojen perustason koulutusmateriaaleista

2003

Application of Potassium Ion Impregnated Titanium Dioxide as Nanocatalyst for Transesterification of Linseed Oil

2018

The current work comprises the investigation of biodiesel production from linseed oil using TiO2 and a potassium L-tartrate monobasic (C4H5KO6)-modified TiO2 nanocatalyst. Different amounts of C4H5KO6 were considered for TiO2 modification. The nanocatalyst TiO2–0.5C4H5KO6 (1:0.5 molar ratio) showed the best conversion rate for biodiesel production. The nanocatalyst was characterized by FTIR, XRD, TEM, BET, and XPS, and the Hammett indicator–benzenecarboxylic acid titration method was used for basicity measurement. The biodiesel was characterized by GC-MS and 1H and 13C NMR. Furthermore, the optimum reaction parameters for transesterification reaction were analyzed, and the yield was determi…

Maailma fossiilitalouden jälkeen

2022

Ilmastonmuutos edellyttää fossiilitaloudesta luopumista. Yhteiskunnan energia- ja materiaperustan muutos vaatii uudenlaisia politiikkakeinoja, rakenteita, toimintatapoja, tuotteita ja hallintamalleja. Ilmastonmuutos johtuu fossiilitaloudesta: öljy- ja maakaasukentiltä ja kivihiilikaivoksista peräisin olevan hiilen pumppaamisesta ilmakehään. Tätä on kiihdyttänyt väestön ja kulutuksen eli talouden kasvu. Jotta ilmastonmuutosta voitaisiin hillitä, fossiilitaloudesta täytyy luopua. Muutos on valtava, kun yhteiskunnan koko metabolinen perusta muuttuu. Meistä kaukana ja näkymättömissä olevista fossiilienergian lähteistä siirrytään meidän keskellämme oleviin energialähteisiin: tuuleen, veteen, aur…

Nanoscale probing of the supramolecular assembly in a two‐component gel by near‐field infrared spectroscopy

2023

The design of soft biomaterials requires a deep understanding of molecular self-assembly. We introduce here a nanoscale infrared (IR) spectroscopy study of a two-component supramolecular gel to assess the system´s heterogeneity and supramolecular assembly. In contrast to far-field IR spectroscopy, near-field IR spectroscopy revealed differences in the secondary structures of the gelator molecules and non-covalent interactions at three distinct nano-locations of the gel network. A β-sheet arrangement is dominant in single and parallel fibres with a small proportion of an α-helix present, while the molecular assembly derives from strong hydrogen bonding. However, at the crossing point of two …

Rapid Self-Healing and Thixotropic Organogelation of Amphiphilic Oleanolic Acid–Spermine Conjugates

2021

Natural and abundant plant triterpenoids are attractive starting materials for the synthesis of conformationally rigid and chiral building blocks for functional soft materials. Here, we report the rational design of three oleanolic acid–triazole–spermine conjugates, containing either one or two spermine units in the target molecules, using the Cu(I)-catalyzed Huisgen 1,3-dipolar cycloaddition reaction. The resulting amphiphile-like molecules 2 and 3, bearing just one spermine unit in the respective molecules, self-assemble into highly entangled fibrous networks leading to gelation at a concentration as low as 0.5% in alcoholic solvents. Using step-strain rheological measurements, we show ra…

Advanced biorefinery concepts related to non-wood feedstocks

2018

Agricultural residues, such as wheat straw (Triticum aestivum), okra stalk (Abelmoschus esculentus), and giant miscanthus (Miscanthus × giganteus, a hybrid of M. sinensis and M. sacchariflorus) were investigated to assess their possible consumption for integrated lignocellulosic biorefining. The efficient fractionation and recovery of all important chemical components (cellulose, hemicelluloses, and lignin) of such feedstocks are a prerequisite for realistic biorefinery concepts. Water is one of the most eco-friendly solvents with the highest potential for industrial use, and it is also suitable for full-scale biorefinery purposes. For example, under pressure at elevated temperatures over 1…

Bidirectional cell-matrix interaction dictates neuronal network formation in a brain-mimetic 3D scaffold

2022

Human pluripotent stem cells (hPSC) derived neurons are emerging as a powerful tool for studying neurobiology, disease pathology, and modeling. Due to the lack of platforms available for housing and growing hPSC-derived neurons, a pressing need exists to tailor a brain-mimetic 3D scaffold that recapitulates tissue composition and favourably regulates neuronal network formation. Despite the progress in engineering biomimetic scaffolds, an ideal brain-mimetic scaffold is still elusive. We bioengineered a physiologically relevant 3D scaffold by integrating brain-like extracellular matrix (ECM) components and chemical cues. Culturing hPSCs-neurons in hyaluronic acid (HA) gels and HA-chondroitin…