Search results for "mineraalit"
showing 10 items of 15 documents
Associations of physical activity intensities, impact intensities and osteogenic index with proximal femur bone traits among sedentary older adults
2021
Background Dynamic high-intensity physical activity is thought to be beneficial for older adults’ bone health. Traditional volume-based processing of accelerometer-measured physical activity data, quantified on a minute-per-minute basis, may average out sporadic high impact activity, whereas accelerometer data processing approaches based on identifying impacts can capture also these potentially beneficial short activity bursts. We investigated the associations between habitual physical activity and proximal femur bone traits among sedentary older adults utilizing three different numerical treatments of accelerometer-data to examine, if impact-based processing approaches are more suitable to…
Optimization of spodumene identification by statistical approach for laser-induced breakdown spectroscopy data of lithium pegmatite ores
2021
Mapping with laser-induced breakdown spectroscopy (LIBS) can offer more than just the spatial distribution of elements: the rich spectral information also enables mineral recognition. In the present study, statistical approaches were used for the recognition of the spodumene from lithium pegmatite ores. A broad spectral range (280–820 nm) with multiple lines was first used to establish the methods based on vertex component analysis (VCA) and K-means and DBSCAN clusterings. However, with a view to potential on-site applications, the dimensions of the datasets must be reduced in order to accomplish fast analysis. Therefore, the capability of the methods in mineral identification was tested wi…
Laser-induced time-resolved luminescence in analysis of rare earth elements in apatite and calcite
2021
Laser-induced time-resolved luminescence was used to study rare earth element (REE) containing natural apatite and calcite minerals. The luminescence from 400 nm to 700 nm in the minerals was analyzed with excitation ranges 210–340 nm and 405–535 nm. As an outcome, several useful excitation wavelengths to detect one or more REE from apatite and calcite are reported. The feasibility of selected excitations in e.g. avoiding the disturbance of intense Mn2+ luminescence band, results was demonstrated with a non-gated detector. peerReviewed
Singular value decomposition approach to the yttrium occurrence in mineral maps of rare earth element ores using laser-induced breakdown spectroscopy
2017
Laser-induced breakdown spectroscopy (LIBS) has been used in analysis of rare earth element (REE) ores from the geological formation of Norra Kärr Alkaline Complex in southern Sweden. Yttrium has been detected in eudialyte (Na15 Ca6(Fe,Mn)3 Zr3Si(Si25O73)(O,OH,H2O)3 (OH,Cl)2) and catapleiite (Ca/Na2ZrSi3O9·2H2O). Singular value decomposition (SVD) has been employed in classification of the minerals in the rock samples and maps representing the mineralogy in the sampled area have been constructed. Based on the SVD classification the percentage of the yttrium-bearing ore minerals can be calculated even in fine-grained rock samples. peerReviewed
Enhanced quantification of wollastonite and calcite in limestone using fluorescence correction based on continuous wavelet transformation for Raman
2020
Raman spectroscopy offers a nondestructive means to identify minerals in rocks, but the ability to use the technology for quantitative mineralogical analysis is limited by fluorescence that can mask the spectral features of minerals. In this paper we apply continuous wavelet transformation (CWT) to remove fluoresence from Raman data acquired from 26 carbonate rock samples. We then record the intensity values of individual spectral features, proxies for mineral abundances, using the original Raman data and the thus inferred CWT data. The intensity values are then compared against the known mineral abundances determined using the scanning electron microscope (SEM) technology. This comparison …
Characterization of spatial porosity and mineral distribution of crystalline rock using X-ray micro computed tomography, C-14-PMMA autoradiography an…
2019
The spatial porosity and mineral distribution of geological materials strongly affects transport processes in them. X-ray micro computed tomography (X-mu CT) has proven to be a powerful tool for characterizing the spatial mineral distribution of geological samples in 3-D. However, limitations in resolution prevent an accurate characterization of pore space especially for tight crystalline rock samples and 2-D methods such as C-14-polymethylmethacrylate (C-14-PMMA) autoradiography and scanning electron microscopy (SEM) are needed. The spatial porosity and mineral distributions of tight crystalline rock samples from Aspo, Sweden, and Olkiluoto, Finland, were studied here. The X-mu CT were use…
Precipitation of potassium as hazenite from washing water of spent alkaline batteries
2022
Hazenite (KNaMg2(PO4)2 × 14 H2O), a new type of struvite mineral, was precipitated from the potassium-rich washing water of spent alkaline battery black mass. Hazenite can be used as a fertilizer, which would be an additional benefit derived from the sustainable recovery of battery materials. Precipitation experiments were performed using different pH values (9.5–12), Mg:K:PO4 ratios ((1.0–1.5):1:(1.0–1.5)) and temperatures (10–40 °C). Based on the results, hazenite precipitated in a wide pH range under alkaline conditions. The precipitation kinetics were fast, and the purity of the hazenite was high. Overall, hazenite can be precipitated at room temperature without the addition of excess c…
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2017
Laserspektroskopia mineraalianalytiikassa : nopeasti ja tehokkaasti monipuolista informaatiota mineraaleista
2022
Laserspektroskopiset menetelmät ovat nopeita ja tehokkaita mineraalitutkimuksen keinoja, koska analyysi voidaan tehdä suoraan näytteen pinnalta ja jopa metrien päästä kohteesta. Nykyteknologian ansiosta laserspektroskopian laitteistoja voidaan lisäksi miniatyrisoida, ja siten ne soveltuvat etämittauksiin esimerkiksi maastossa, linjastolla tai kaivoksessa (in situ). Tässä artikkelissa esitellään laserindusoitu plasmaspektroskopia (LIBS), laser-indusoitu luminesenssispektroskopia ja Raman-spektroskopia, joilla saadaan näytteistä toisiaan täydentävää informaatiota (Romppanen 2021). Tunnetuimmat esimerkit laserspektroskopian soveltuvuudesta mineraalianalytiikassa löytyvät Marsista, sillä planee…