Search results for "Microstructure"
showing 10 items of 707 documents
Reconstruction of 3D grain boundaries from rock thin sections, using an advanced polarised-light microscopy method
2017
Grain boundaries play a significant role in materials by initiating reactions and collecting impurities. Here we present FAGO (Fabric Analyser Grain boundary recOnstruction), a first step towards the automatic determination of three-dimensional (3D) grain boundary geometry using polarised light. The trace of the grain boundaries from 2D rock thin sections are determined primarily from data acquired using an automatic fabric analyser microscope and the FAME software (fabric analyser-based microstructure evaluation; Peternell and colleagues and Hammes and Peternell). Based on the Fabric Analyser G50's unique arrangement of nine differently oriented light sources the retardation can be determi…
Presentation of the DSIP method for study of recrystallization process in subsurface zone induced by sandblasting
2011
In the paper we demonstrate the application of the positron annihilation experimental technique based on the scan of the positron implantation profile for observation of the recrystallization process in the subsurface zone (SZ). The SZ was created in the copper sample whose surface was exposed to a sandblasting treatment and then annealed at different temperatures. Application of 68Ge/68Ga positron source allows us to scan the depth of c.a. 150 μm. It was found that recrystallization goes faster close to the surface than in deeper regions. The complete rebuilding of the microstructure takes place at temperature of 600 °C. Some changes in the defect structure begin at temperature of 300 °C.
Gas-phase supersaturation effects on morphology properties of ZnO nano and microstructures grown by PVT
2016
A systematic study of the morphology evolution of ZnO nanostructures grown by physical vapour transport was carried out. The evolution of the shape with the growth time is shown to depend on the different gas-phase supersaturation and temperature conditions encountered in the crystallization zone of the tube furnace. The observed morphology transitions are discussed, and a growth model for ZnO nanostructures is given.
The effects of sodium alginate and calcium levels on pea proteins cold-set gelation
2013
Abstract A multi-scale investigation of pea proteins – alginate cold-set gels was proposed in this study. The gel preparation followed a two-steps procedure. Globular pea proteins were first denatured and aggregated by a pre-heating step. Sodium alginate was then added at different concentrations. Thereafter the in situ gelation process was induced at 20 °C using glucono-δ-lactone (GDL) and two calcium carbonate (CC) levels; calcium cations were released as the pH decreased. Small-amplitude rheology measurements (storage modulus G′) showed that stronger mixed gels were obtained than single-biopolymer solutions. Confocal laser scanning microscopy (CLSM) revealed phase-separating microstructu…
Patterns of trading profiles at the Nordic Stock Exchange. A correlation-based approach.
2016
We investigate the trading behavior of Finnish individual investors trading the stocks selected to compute the OMXH25 index in 2003 by tracking the individual daily investment decisions. We verify that the set of investors is a highly heterogeneous system under many aspects. We introduce a correlation based method that is able to detect a hierarchical structure of the trading profiles of heterogeneous individual investors. We verify that the detected hierarchical structure is highly overlapping with the cluster structure obtained with the approach of statistically validated networks when an appropriate threshold of the hierarchical trees is used. We also show that the combination of the cor…
Micro and Nano patterns for Biosensing: from enzymatic assays to single cells interaction arrays
2012
In this thesis work, solution dispensing techniques have been employed for the realization of complex biological arrays. Inkjet printing techniques were employed for the generation of drug screening platforms. This approach was initially proved with a model enzyme system like Glucose Oxidase substrate covalently linked to a functionalized silicon oxide support. On this support an enzymatic substrate (D-glucose)/inhibitor (D-glucal) couple was accurately dispensed. A simple optical detection method was used to prove the screening capability of the microarray with the possibility to assay with high reproducibility at the single spot level. Afterwards, this methodology has been extended to CYP…
New Materials Design Through Friction Stir Processing Techniques
2007
Friction Stir Welding (FSW) has reached a large interest in the scientific community and in the last years also in the industrial environment, due to the advantages of such solid state welding process with respect 1(o) the classic ones. The complex material flow occurring during the process plays a fundamental role in such solid state welding process, since it determines dramatic changes in the material microstructure of the so called weld nugget, which affects the effectiveness of the joints. What is more, Friction Stir Processing (FSP) is mainly being considered for producing high-strain-rate-superplastic (HSRS) microstructure in commercial aluminum alloys. The aim of the present research…
Oxidation of niobium sheets at high temperature
1997
Abstract This work shows the role of oxygen pressure on growth kinetics, morphology, phase composition and texture of oxide scale in the oxidation of niobium sheets at 900 °C. The particular morphology observed at low pressure shows the existence of competition between edge and surface growth mechanisms. Pressure and conversion rate influence the nature of preferential orientations of the Nb2O5 oxide layer: a [110] fibre axis is stabilized at high pressure but, at low pressure, the higher is the conversion rate, the more evident is this fibre axis. This behaviour is observed not only after cooling but also in situ. At high pressure, the evolution is not only temporal but also spatial: with …
Impact of oxidoreduction potential and of gas bubbling on rheological properties of non-fat yoghurt
2010
International audience; The aim of this work was to study the effect of different gaseous conditions on the physico-chemical properties of yoghurt. Four conditions of oxidoreduction potential (Eh7), +433 mV (milk gassed with air), +405 mV (ungassed milk), +283 mV (milk gassed with N2) and −349 mV (milk gassed with N2–H2) were applied to milk. The rheological properties and microstructure of these yoghurts were determined by measuring apparent viscosity, whey separation (WS) and using confocal laser scanning microscopy. Exopolysaccharide (EPS) production by lactic acid bacteria (LAB) was also studied, and production was increased for extreme Eh7 values: the highest values were obtained for a…
FRACTAL STRUCTURES IN SINGLE CRYSTALS OF FERROELECTRIC LITHIUM NIOBATE GROWN UNDER STRONGLY UNSTABLE CONDITIONS
2009
Atomic force microscopy studies of lithium niobate single crystals containing heterogeneously distributed lanthanide (Gd) admixture and a regular domain structure of 100 nm to 1 μm steps obtained under conditions of severe thermal instability have revealed fractal structures of the size of 10 to 100 nm within regions of the regular domain structures. A super-structure of clustered defects with 1–2 nm steps explaining results of Raman spectra analysis is supposed to exist in the cation sub-lattice and formation of periodic fractal structures of the size of ∼1 nm–100 μm is suggested to take place in lithium niobate single crystals containing lanthanide admixture.