Search results for "magnetite"
showing 10 items of 98 documents
Mapping of corrosion products of highly altered archeological iron using voltammetry of microparticles
2013
The application of the voltammetry of microparticles to identify corrosion products on different localizations of highly altered archeological iron pieces is described. The use of graphite pencil methodology permits to mapping different corrosion products, namely, akaganeite, goethite, hematite, jarosite, magnetite, maghemite and siderite, in iron artifacts. Identification protocols are based on square wave voltammetric measurements performed at sample-modified paraffin-impregnated graphite electrodes immersed into aqueous HCl. This methodology is applied for mapping corrosion products on an Iberian Roman shield boss from the Torre la Sal archeological site (Oropesa, Spain) dated in the IVt…
Identification of Earth Pigments by Applying Hierarchical Cluster Analysis to Solid State Voltammetry. Application to Severely Damaged Frescoes
2007
Multivariate chemometric methods are applied for identifying earth pigments from square-wave voltammetric measurements performed at pigment-modified paraffin-impregnated graphite electrodes allowing for a separation between hematite-based earths, French ochres, Spanish ochres, siennas, umbers and green earths. This methodology is applied to the identification of the pigments in samples from the ceiling frescoes of Antonio Palomino (dated 1707) in the vaulted nave of the Sant Joan del Mercat church in Valencia (Spain). These frescoes suffered considerable damage by fire during the Spanish Civil War in 1936, resulting in severe chemical and chromatic alterations. Electrochemical data, support…
Abiotic versus biotic iron mineral transformation studied by a miniaturized backscattering Mössbauer spectrometer (MIMOS II), X-ray diffraction and R…
2017
Abstract Searching for biomarkers or signatures of microbial transformations of minerals is a critical aspect for determining how life evolved on Earth, and whether or not life may have existed in other planets, including Mars. In order to solve such questions, several missions to Mars have sought to determine the geochemistry and mineralogy on the Martian surface. This research includes the two miniaturized Mossbauer spectrometers (MIMOS II) on board the Mars Exploration Rovers Spirit and Opportunity, which have detected a variety of iron minerals on Mars, including magnetite (Fe2+Fe3+2O4) and goethite (α-FeO(OH)). On Earth, both minerals can derive from microbiological activity (e.g. thro…
Characterisation of the magnetic iron phases in Clovis Class rocks in Gusev crater from the MER Spirit Mössbauer spectrometer
2007
Abstract Mossbauer backscattering spectra of eight Martian rocks, acquired by the MIMOS II spectrometer of Rover Spirit (MER-A) and containing goethite in addition to other iron minerals, have been selected for in-depth numerical analysis. Where feasible, different temperature windows for a given rock were considered. A novel calibration/folding procedure, exclusively based on the fitted positions of the eight prominent absorption lines in the transmission spectra of the reference target and not relying on the error signal of the MIMOS II spectrometer, has been developed. It is demonstrated that this procedure yields reliable and reasonably accurate values for the adjusted Mossbauer paramet…
Inulin-based polymer coated SPIONs as potential drug delivery systems for targeted cancer therapy
2014
This paper deal with the synthesis and characterization of PEGylated squalene-grafted-inulin amphiphile capable of self-assembling and self-organizing into nanocarriers once placed in aqueous media. It was exploited as coating agent for obtaining doxorubicin loaded superparamagnetic iron oxide nanoparticles (SPIONs) endowed with stealth like behavior and excellent physicochemical stability. Inulin was firstly modified in the side chain with primary amine groups, followed in turn by conjugation with squalenoyl derivatives through common amidic coupling agents and PEGylation by imine linkage. Polymer coated SPIONs were so obtained by spontaneous self-assembling of inulin copolymer onto magnet…
Size-isolation of superparamagnetic iron oxide nanoparticles improves MRI, MPI and hyperthermia performance.
2020
Journal of nanobiotechnology 18, 22 (2020). doi:10.1186/s12951-020-0580-1
Cell uptake enhancement of folate targeted polymer coated magnetic nanoparticles.
2013
Dual targeted drug delivery systems represent a potential platform for developing efficient vector to tumor sites. In this study we evaluated a folate- and magnetic-targeted nanocarriers based on 10 nm iron oxide nanodomais coated with the properly synthesized and characterized folic acid (FA)-functionalized amphiphilic copolymer PHEA-PLA-PEG-FA. FA was chemically conjugated to one end of diamino-polyethylene glycol of 2000 Da, in order to ensure its exposition on the polymer coated magnetic nanoparticles (MNPs-FA). The prepared nanoparticles have been exhaustively characterized by different methods, including DLS, SEM, FT-IR and magnetic measurements. Magnetic nanoparticles showed dimensio…
Synthesis and characterization of nanoparticles with an iron oxide magnetic core and a biologically active trialkylsilylated aliphatic alkanolamine s…
2007
Water-soluble double-coated magnetic nanoparticles (NPs) containing cytotoxic decyldimethyl(β-dimethylaminoethoxy)silane methiodide (AA) molecule sorbed at biocompatible magnetic particles, which consist of magnetite pre-coated with oleic acid (OA), have been prepared. X-ray line profile broadening analysis was used for crystallite size determination. The method of magnetogranulometry has been used for determination of diameter of iron oxide magnetic core and magnetic properties of NPs prepared. In vitro cytotoxicity on monolayer tumor cell lines HT-1080 (human fibrosarcoma), MG-22A (mouse hepatoma) and normal mouse fibroblasts (NIH 3T3) has been studied. It was revealed that all the water-…
Synthesis, physico-chemical and biological study of trialkylsiloxyalkyl amine coated iron oxide/oleic acid magnetic nanoparticles for the treatment o…
2008
New original water-soluble magnetic nanoparticles based on natural components, magnetite–oleic acid–biologically active silyl modified alkanolamine, were synthesized. Physico-chemical characterization, i.e. magnetic properties, concentration of magnetite, size of iron oxide core, of the nanoparticles synthesized and the corresponding magnetic fluids obtained, was carried out. Magnetic fluids were screened for in vitro cytotoxicity concerning human fibrosarcoma (HT-1080), mouse hepatoma (MG-22A) monolayer tumour cell lines and normal mouse fibroblasts (NIH 3T3). They possess low or moderate cytotoxic effects, are non-toxic, exhibit high NO-induction ability and strongly change tumour cell mo…
Magnetic characteristics of industrial dust from different sources of emission: A case study of Poland
2015
Abstract Dust emission and deposition in topsoil have negative effect on individual components of the ecosystem. In addition to routine geochemical analyses, magnetic measurements may provide useful complementary information related to the type, concentration and grain-size distribution of the technogenic magnetic particles (TMPs) and thus the degree of contamination of the environment. The aim of this contribution is to use magnetic parameters in distinguishing dust from a wide range of sources of air pollution (power industry, cement, coke, ceramic industries and biomass combustion). We measured magnetic susceptibility, hysteresis parameters and thermomagnetic curves. Our results suggest …