<p>To increase the understanding of contaminant transport, specifically biocolloid transport in fractured media, a series of experiments were conducted on single saturated fractures. Hydraulic and solute tracer tests were used to characterize three separate fractures: one natural fracture and two synthetic fractures. Zeta potentials are reported showing the high negative electric charge of the synthetic fractures relative to the natural fractures in the phosphate buffer solution (PBS) used during the biocolloid tracer tests.</p> <p><em>E. coli</em> RS2-GFP tracer tests were conducted on all three fractures at specific discharges of 5 m/d, 10 m/d and 30 m/d. Lower <em>E. coli</em> recovery was consistently observed in the natural fracture, due to 1) attachment because of the lower negative charge of the natural fracture relative to the synthetic fracture; and 2) the presence of dead end fractures within the fracture matrix. In the synthetic fractures, where surface charges were equal, in the larger, more variable fracture aperture, lower recoveries were found when compared to the smaller, less variable fracture aperture, which was not expected. This indicates that aperture variability plays a larger role than fracture aperture size in the retention of biocolloids in fractures.</p> <p>Differential transport was consistently observed in all three fractures, but was more prominent in the synthetic fractures. This indicates that charge exclusion plays a more dominant role in the differential transport of colloids than size exclusion, though size exclusion cannot be eliminated as a retention mechanism based on these experiments. Differential transport was also heavily influenced by specific discharge as the difference in arrival times between the bromide and <em>E. coli</em> increased in all three fractures as the specific discharge decreased.</p> <p>Visualization tests were completed on the synthetic fractures showing the location of multiple preferential flow paths, as well as areas with low flow.</p>

This thesis describes laboratory measurements of the complex refractive index of volcanic ash particles. These measurements are needed to model the radiative impact of volcanic ash, vital for accurate satellite remote sensing. Three experimental methods have been developed, and the results for the complex refractive index and optical properties of a wide range of volcanic ash samples are presented. Measurements were made of the spectral transmission of radiation through suspended volcanic ash particles inside an aerosol cell, using a Fourier transform spectrometer at infrared wavelengths and two diffraction grating spectrometers covering ultraviolet, visible, and near-infrared wavelengths. In addition to the optical measurements, a suite of sampling and sizing instruments were connected downstream of the aerosol cell to measure the particle size distribution. The method was calibrated using two quartz samples. Mass extinction coefficients for nine volcanic ash samples, at 0.3-14 μm, are presented and show considerable variation. These variations are linked to the composition of the samples, measured using X-ray fluorescence (XRF) analysis. The complex refractive index, at 0.3-14 μm, of the two quartz samples and two samples of volcanic ash from the 2010 Eyjafjallajökull eruption were retrieved from the extinction measurements. The forward model used Mie theory and a classical damped harmonic oscillator (CDHO) model to represent the complex refractive index of the samples in terms of a finite set of band parameters, as well as the real refractive index of the sample in the small wavelength limit. Previous studies have shown that there is a redundancy in the retrievals between the band strength parameters and the real refractive index in the small wavelength limit, which can lead to spurious values for the retrieved complex refractive index. This problem was overcome by using an independent measurement of the real refractive index at a visible wavelength, to constrain the model parameter of the real refractive index in the short wavelength limit. Independent measurements of the complex refractive index at visible wavelengths are also important because the extinction produced at these wavelengths is highly sensitive to the particle size distribution, and any uncertainty in the measured size distribution will contribute to significant systematic error in the refractive index retrieved from extinction. The retrieved spectral complex refractive index of Eyjafjallajökull ash was applied using the ORAC retrieval scheme to measurements of the 2010 Eyjafjallajökull eruptionmade by theMODIS instrument aboard NASA's Terra satellite. Significant difference were found in the retrieved plume parameters of optical path, effective radius, and plume altitude, compared to assuming a literature measurement for the refractive index of pumice. For three discrete visible wavelengths (450, 546.7, and 650 nm) an optical microscope was used to make measurements of the complex refractive index of the volcanic ash samples. The long-established Becke line method was used to measure the real refractive index of the samples. For the imaginary refractive index, a new and novelmethod was developed involving measurements of the attenuation of light in individual particles. A strong linear correlation was found between the SiO₂ content of the samples and both their real and imaginary refractive indices at the visible wavelengths investigated. Furthermore, from the XRF compositional analysis of the samples values were calculated for the ratio of non-bridging oxygen atoms per tetrahedral cation (NBO/T), and it was found that NBO/T was an even stronger predictor of real refractive index at visible wavelengths. The optical microscope measurements could only be applied to particles with a radius larger than 10 μm. A new refractometer method was investigated for retrieving the real refractive index of submicron particles from colloidal reflectance measurements close to the critical angle in an internal reflection configuration. A coherent scattering model (CSM) was used to model the coherent reflection from a half-space of monodisperse or polydisperse particles, and a simple extension of the model is presented to properly account for the modified size distribution at the interface in an internal reflection set-up. A rigorous sensitivity analysis was performed to determine how experimental uncertainties propagate into uncertainty associated with the retrieved real refractive index, and the uncertainty due to non-spherical effects was estimated using T-matrix methods. Experimental reflectance data at a wavelength of 635 nm were obtained for spherical monodisperse polystyrene calibration particles, a polydisperse sand sample, and a polydisperse volcanic ash sample. The retrieved values for the real refractive index agreed, within propagated uncertainties, with values measured using other techniques. The method is shown to be a viable technique for measuring the real refractive index of small quantities of submicron particles, and can also retrieve the concentration and size of particles.

Polymer brushes are extremely versatile materials, as monomer choice allows the user to design a material with the desired physiochemical properties. Given the wide variety in monomer functionality, polymers can be fine-tuned for a specific application. In this work, polymer brushes bound to a silica support are designed and utilized to enhance performance of protein extraction and chromatographic separations. <br> The effectiveness of an analytical method is strongly affected by matrix composition, however, the presence of species other than the target analyte is usually unavoidable. An excellent technique will be able to identify and/or quantify the analyte even when its concentration is low compared with interfering molecules. Protein analysis is particularly challenging, since many proteins of clinical and scientific significance are present in complicated matrices such as plasma or cell lysates. <br>A common method to specifically separate a protein from a complicated matrix is solid phase extraction. In this method, a species (such as an antibody) with high specificity towards the target is immobilized onto a solid substrate (commonly beads or small particles for greater surface area). Next, the target is collected onto the surface, bound by the species. The solid substrate is rinsed of the liquid matrix, before elution of the target. Only the active species should interact with the analyte, and the surface should be otherwise inactive. However, nonspecific interactions lead to binding/adsorption of undesirable compounds. Therefore, an optimal substrate for protein extraction must be 1) easily and completely removable from the liquid phase, 2) have a high concentration of active sites for specific binding, and 3) exhibit low nonspecific binding. As part of this work, commercial magnetic particles were coated with a nonporous silica layer that tolerates the acid bath and silane coating necessary to attach a polymer layer. On the silane coating, a polymer layer was covalently bound; this layer contains epoxide active groups for immobilizing antibodies. These antibodies bind to the target molecule with high specificity, and low nonspecific binding. Obtained particles were evaluated for protein extraction, where antibodies as well as specifically engineered drug compounds were successfully bound to the particle surface.<br>Glycosylation influences several physiopathological processes in proteins. Glycans can act as receptors, modify protein solubility, and participate in folding conformation. Altered glycosylation is a common feature in tumorous cells. As such, many modifications in glycoproteins have been related to cancer, including increased branching of N-glycans or augmented units of sialic acid. Therefore, characterization of glycoproteins is important not only as a diagnostic tool, but also to monitor patients’ response to treatment. Furthermore, it is important in the growing field of monoclonal antibodies as drug carriers. <br>Among different methods used for glycosylation analysis, Hydrophilic Interaction Liquid Chromatography (HILIC) has showed important advantages over time-consuming digestion-MS based techniques. An adequate HILIC stationary phase can be used to rapidly differentiate glycoforms present in a sample. In the second part of this work, a polymer brush based bonded phase was developed as a HILIC stationary phase. The new polymer improved the separation of a model glycoprotein compared with a commercial HILIC column, while also exhibiting enhanced stability over a previous bonded phase synthetized in our group.<br><br>

Despite the central importance of porous electrodes to any advanced electrochemical system, there is no clear answer to “<i>How to make the best electrode</i>?”. The source of ambiguity lies in the incomplete understanding of convoluted material interactions at smaller – difficult to observe length and timescales. Such mesoscopic interactions, however, abide by the fundamental physical principles such as mass conservation. The porous electrodes are investigated in such a physics-based setting to comprehend the interplay among structural arrangement and off-equilibrium processes. As a result, a synergistic approach exploiting the complementary characteristics of controlled experiments and theoretical analysis emerges to allow mechanistic insights into the associated mesoscopic phenomena. The potential of this philosophy is presented by investigating three distinct electrochemical systems with their unique peculiarities.

The objective of this research is to develop and apply a HILIC UHPLC stationary phase that allows for separation of intact glycoproteins. In Chapter 1 I give an overview of the problems of current glycosylation profiling with regards to biotherapeutics, and my strategy to separate the intact glycoprotein with HILIC. Chapter 2 describes the methods used to produce the nonporous packing material and stationary phase. In Chapter 3 I describe previous work in developing a HILIC polyacrylamide stationary phase, and further improvements I have made. Chapter 4 describes development of an assay in collaboration with Genentech of therapeutic mAb glycosylation. In Chapter 5, I show HILIC-MS of digested ribonuclease B as a beginning step to analyze glycosylated biomarkers.

Les liquides complexes sont des matériaux très prometteurs pour réaliser la conversion bon marché et à grande échelle d’énergie thermique en énergie électrique, dans un contexte de réchauffement climatique et de maîtrise de la consommation d’énergie. Nous montrons qu’en présence d’un couple redox, les cellules thermogalvaniques à base de liquides ioniques (NEA et EMIMTFSI) présentent des propriétés remarquables tels des coefficients Seebeck de plus de 5 mV/K (Eu³⁺/Eu²⁺ dans l’EMIMTFSI). De même, ces travaux présentent l’utilisation de ferrofluides, solutions colloïdales (aqueuses ou à base de solvants organiques) de nanoparticules magnétiques (maghémite), pour accroître le coefficient Seebeck et le courant extractible de générateurs thermoélectriques liquides. Les phénomènes réversibles d’adsorption des nanoparticules sur la surface des électrodes jouent également un rôle important sur les propriétés thermoélectriques de ces solutions, et sont modifiés par l’application de champs magnétiques homogènes parallèles ou perpendiculaires au gradient de température.En l’absence d’un couple redox, les liquides ioniques peuvent être utilisés pour fabriquer des supercondensateurs à charge thermique. Ces derniers exploitent les modifications avec la température des double couches électriques aux interfaces liquide/électrode. Nous avons étudié ici ces modifications de double couches dans l’EMIMBF4 par simulations numériques de Monte-Carlo. Les résultats démontrent un accroissement conséquent des propriétés thermoélectriques lors de la dilution du liquide ionique dans un solvant organique, l’acétonitrile, en accord qualitatif avec les résultats expérimentaux. / Complex liquids are promising material for low cost and wide scale conversion of thermal energy to electric energy, within a context of global warming and control of the energy consumption.In this work we showed that with a redox couple, ionic liquid (EAN and EMIMTFSI) based thermogalvanic cells present remarkable thermoelectric properties such as the Seebeck coefficient over 5 mV/K (Eu³⁺/Eu²⁺ in EMIMTFSI). Moreover, we demonstrated for the first time that ferrofluids, colloidal solutions (aqueous or organic solvent based) of magnetic nanoparticles (maghemite), can be used to increase both the Seebeck coefficient and the electric current in liquid thermoelectric generators through unknown physical processes. The importance of reversible adsorption phenomena of the nanoparticles on the electrodes’ surface for the thermoelectric properties of these solutions was revealed. That can be further modified by a homogeneous magnetic field applied perpendicular or parallel to the temperature gradient. Without a redox couple, ionic liquids can be used to build thermally chargeable supercapacitors. They take advantage of temperature dependent electrical double-layer formation at liquid/electrode interfaces. Here, we studied these double-layer modifications in EMIMBF4/platinum through Monte-Carlo simulations. The results show substantial modifications in the thermoelectric properties when the ionic liquid is diluted in an organic solvent, acetonitrile. These results are qualitatively consistent with experimental measurements.

La terre crue est un des matériaux les plus utilisés au monde pour bâtir. Chaque terre est un mélange de grains de différentes tailles (cailloux, graviers, sables, silts et argiles) en proportions variées. Les particules les plus fines, qui constituent le liant du matériau, se différencient des autres grains par leur petite taille, à laquelle est associée des propriétés colloïdales lorsqu’elles sont mélangées à l’eau. L’argile, au sens granulométrique (particules inférieures à deux microns), contient généralement un mélange d’argiles, au sens minéralogique (phyllosilicates hydratés), d’oxydes de fer, d’aluminium et de silicium. Pour comprendre ce matériau de construction, la terre est envisagée dans un premier temps comme une matière en grains. La physique des milieux granulaires secs et la physique des milieux granulaires humides sont explorées afin de décrire les comportements physiques de cette matière. Des techniques de construction innovantes, qui découlent de cette compréhension, sont présentées. Dans un deuxième temps, l’argile est envisagée comme une matière colloïdale. Comme beaucoup de systèmes naturels, le liant argileux est un mélange de particules aux propriétés de surface différentes, contenant à la fois des charges permanentes négatives et des charges variables avec le pH et la force ionique. Ces systèmes mixtes sont dits hétérocoagulés. Des pistes de recherche, qui découlent de cette compréhension, sont présentées. / Raw earth is one of the most used building material in the world. Each earthen material is a mix of different sizes grains (stones, gravels, sands, silts and clays) in various proportions. The finest particles, which constitute the binding material, differ from other grains by their small size, which is associated with colloidal properties when mixed with water. Clay, as defined by size (particles smaller than two microns), usually contains a mixture of clays, as defined by mineralogy (hydrated phyllosilicates), with iron, aluminum and silicium oxides. To understand this building material, earthen material is considered initially as a granular material. Physics of dry granular media and physics of wet granular media are explored in order to describe the physical behavior of this material. Innovative building systems, which come from this understanding, are presented. In a second step, clay is considered as a colloidal material. Like many natural systems, clay binder is a mixture of particles with different surface properties, containing both permanent negative charges and variable charges, depending of pH and ionic strength. These mixed systems are called heterocoagulated systems. Different sujects for further researches, that follow this understanding, are presented.

The hydrophobicity of a surface is an important property in many areas of science and engineering. This is especially the case in mineral processing, where differences in surface hydrophobicity lie at the heart of the separation process of flotation. Chemicals are used to increase and decrease the natural hydrophobicity of minerals to attain a better separation between valuable and worthless material. Polymers are often used to reduce mineral surface hydrophobicity. Decades of empirically based decision making have produced a list of effective depressants. However the detailed study of how these polymer depressants affect surface hydrophobicity and mineral recovery lags behind applied investigations. The aim of this thesis was to study the adsorption of commonly used depressants on model surfaces and to interrogate the action of these polymers in reducing surface hydrophobicity. We have modelled the degree of hydrophobicity of common minerals in order to study polymer depressants with methods not commonly used in studies of surface characterisation in flotation. The model surfaces (self-assembled monolayers, SAMs) allowed us to use the quartz crystal microbalance with dissipation monitoring (QCM-D) to study the adsorption of polymers. The QCM-D can be used to obtain adsorption isotherms, adsorption kinetics, water content of adsorbed layers, and information on the conformation of the adsorbed polymer. The results from the QCM-D were correlated with the contact angle data from the captive bubble measurements, with which we assessed the hydrophobicity of the surface before and after polymer adsorption. Three of the polymers layers were probed with dynamic dewetting studies, in order to test other modes of depressant action. Three types of polymers were studied - a polyacrylamide (Polymer-H), a polyelectrolyte CMC (carboxymethyl cellulose) and a group of dextrins (Dextrin-TY, a phenyl succinate substituted dextrin (PS Dextrin) and a styrene oxide substituted dextrin (SO Dextrin)). These polymers are commonly used or have potential to be used in the depression of talc and graphite. Polymer-H was used to investigate the hydrophobic bonding between a non-ionic polymer depressant and chemically inert and non charged surfaces by probing the influence of substrate hydrophobicity on polymer adsorption and reduction of contact angle. Three different model surfaces were used (mixed self-assembled 0.5 SAM, 0.7 SAM or single self-assembled 1.0 SAM monolayers) with advancing contact angles between 75?? and 119??. The study of Polymer-H found that the substrate hydrophobicity is an important factor in adsorption of this polymer and the change in contact angle upon adsorption depends on adsorbed amount. The effectiveness of Polymer-H to reduce surface hydrophobicity was established to correlate with its conformation and morphology. CMC was investigated to find out how a stimulus responsive polymer depressant can be used in flotation. It was established that the adsorbed amount and rate of adsorption of CMC increase with decreasing of pH or increasing of ionic strength. It was shown that the surface hydrophobicity of a CMC pre-adsorbed layer changes with the environment and these alterations are fully reversible. A switch of ionic strength (from 10-2 M KCl to 10-1 M KCl) caused partial dehydration of the adsorbed layer and a decrease of the receding contact angle by 20??. A pH switch (pH = 9 to pH = 3) resulted in a 40?? change in receding contact angle. The CMC investigation showed that the use of a stimulus responsive polymer presents opportunities for exploiting solution conditions as a means to effect a better mineral separation in flotation The adsorption of three dextrin-based polymers on a model hydrophobic surface has been characterized using the quartz crystal microbalance with dissipation monitoring (QCM-D). The three polymers (one standard dextrin and two dextrins with different aromatic group substitutions) exhibited varying affinities and capacity for adsorption on the hydrophobic substrate. The effect of the three polymers on the static contact angle of the surface was studied using captive bubble contact angle measurements. The three polymers were seen to reduce the receding contact angle by similar amounts (approximately 14 degrees) in spite of having varying adsorbed amounts and differences in adsorbed layer water content. Although no differences were observed in the ability of the polymers to reduce the static contact angle, measurements of the dewetting dynamics between a rising air bubble and the polymer covered substrate yielded stark differences between the polymers, with one polymer slowing the dewetting dynamics by an order of magnitude more than the other two polymers. The differences in dewetting behaviour correlate with the adsorbed layer characteristics determined by QCM-D. / Thesis (PhD)--University of South Australia, 2010

Poor settling of solids increases land requirement for tailings containment and imposes severe constraints on the water balance. Consequent to these considerations, the alternating current electrocoagulation (AC/EC) technique emerged as a candidate for enhancing the settling behaviour of suspensions in the mineral, coal and oil sands industries. Hence, a fundamental study of AC/EC was undertaken with aluminum electrodes. Ground silica (d50 = 20 m), which formed a stable suspension, served as the model tailings solid at 5.0 wt % in water. The AC/EC process consisted of two developmental stages: coagulation, marked by pH decrease in the silica suspension; and floc growth, characterized by pH increase from the minimum (i.e., the end of coagulation). AC/EC enhanced the initial settling rate of silica by over three orders of magnitude, and exhibited remarkable flexibility by virtue of the wide range of process parameters that could be optimized. For example, AC/EC can be operated in either the indirect or direct mode. The settling behaviour of bentonite (estimated d50 < 1 m) was more enhanced by indirect AC/EC, while that of silica benefited more from direct AC/EC. Any condition that increased aluminum dosage (e.g., current, retention time), increased the initial settling rate of silica. Over the feed water pH range of 3.0 to 9.1, AC/EC was effective in enhancing the settling behaviour of silica. AC/EC was also effective over a wide range of temperatures (23 to 85C). High electrical energy demand by AC/EC was observed throughout this study. Its optimization was beyond the scope of this work. Dilution of a sample of Syncrude mature fine tailings (MFT) to 4.6 wt % solids sustained a stable suspension. Settling occurred after AC/EC treatment, a crystal-clear supernatant resulted and bitumen was recovered as froth. Entrained solids were easily spray-washed from the froth with water. The settling behaviour of a Luscar Sterco fine coal tailings sample was not augmented by AC/EC, possibly due to contamination by the companys own electrocoagulation operation. After having been stored dry for more than a year, electrocoagulated silica was an effective coagulant for as-received silica and Syncrude MFT. / Chemical Engineering

Ein Spezialgebiet der modernen Mikroelektronik ist die Miniaturisierung und Entwicklung von neuen nanostrukturierten und Komposit-Materialen aus 3d-Metallen. Durch geeignete Zusammensetzungen können diese sowohl mit einer hohen Sättigungsmagnetisierung und Koerzitivfeldstärke als mit besserer Oxidationsbeständigkeit im Vergleich zu den reinen Elementen erzielt werden.<br /> <br /> In der vorliegenden Arbeit werden neue Methoden für die Herstellung von bimetallischen kolloidalen Nanopartikeln vor allem mit einer Kern-Hülle-Struktur (Kern@Hülle) präsentiert. Bei der überwiegenden Zahl der vorgestellten Reaktionen handelt es sich um die thermische Zersetzung von metallorganischen Verbindungen wie Kobaltcarbonyl, Palladium- und Platinacetylacetonate oder die chemische Reduktion von Metallsalze mit langkettigem Alkohol in organischem Lösungsmittel. Daneben sind auch Kombinationen aus diesen beiden Verfahren beschrieben. Es wurden Kolloide aus einem reinen Edelmetall (Pt, Pd, Ag) in einem organischen Lösungsmittel synthetisiert und daraus neue, bisher in dieser Form nicht bekannte Ag@Co-, Pt@Co-, Pd@Co- und Pt@Pd@Co-Nanopartikel gewonnen.<br /> <br /> Der Kobaltgehalt der Ag@Co-, Teilchen konnte im Bereich von 5 bis 73 At. % beliebig eingestellt werden. Der mittlere Durchmesser der Ag@Co-Partikel wurde von 5 nm bis 15 nm variiert. Bei der Herstellung von Pt@Co-Teilchen wurde eine unterschiedlich dicke Kobalt-Hülle von ca. 1,0 bis 2,5 nm erzielt. Im Fall des Palladiums wurden sowohl monodispere als auch polydisperse Pd-Nanopartikel mit einer maximal 1,7-2,0nm dicken Kobalthülle synthetisiert.<br /> <br /> Ein großer Teil dieser Arbeit befasst sich mit den magnetischen Eigenschaften der kolloidalen Teilchen, wobei die SQUID-Magnetometrie und Röntgenzirkulardichroismus (XMCD) dafür eingesetzt wurden. Weil magnetische Messungen alleine nur indirekte Schlüsse über die untersuchten Systeme erlauben, wurde dabei besonderer Wert auf die möglichst genaue strukturelle Charakterisierung der Proben mittels moderner Untersuchungsmethoden gelegt. Röntgendiffraktometrie (XRD), Röntgenabsorptionsfeinstruktur- (EXAFS) und UV-Vis-Spektroskopie sowie Transmissionselektronenmikroskopie (TEM) in Kombination mit Elektronen Energieverlustspektroskopie (EELS) und energiedispersive Röntgenfluoreszensanalyse (EDX) wurden verwendet. / Magnetic colloidal particles are attractive because of their possible application to ultra-high-density magnetic data storage media, sensors, electronic devices and medical diagnostics. The properties of small particles depend on their composition, shape, and method of preparation. The combination of 3d-metals (Fe, Co, Ni) with noble metals improves the stability of the colloids and leads to new properties of the magnetic systems, often distinct from those of the corresponding monometallic particles. Core-shell particles, where dia- or paramagnetic noble metal-cores are surrounded by a ferromagnetic Co-shell, are an interesting system to study surface and interfacial magnetism such as an induced polarization or a giant magnetoresistance effect. <br /> <br /> In this work, new synthetic routes for the preparation of monometallic (Pt, Pd, Ag) and bimetallic magnetic nanocrystals (Ag@Co, Pt@Co, Pd@Co) with core-shell structure are presented. Stable colloids with a narrow particle size distribution were obtained in organic solvents using methods of wet chemistry. The method of preparation of Ag@Co is based on the thermal decomposition of dicobalt octycarbonyl in combination with a transmetalation reaction with water free AgClO4. The cobalt amount in the Ag@Co system could be tuned from 5 to 73 at. %. The average diameter of the particles was varied from 5 to 15 nm. <br /> <br /> The reduction of platinum and palladium salts in organic solution using long chained alcohol as the reductant leads to stable metal nanostructures. Monodisperse Pd and Pt particles with average sizes of 1.7 to 7.0 nm were synthesized via thermal decomposition of metal-surfactant complexes too. Alkylamines and alkylphosphines were used in this procedure. The thickness of the Co-shell was controlled by a simple high-temperature thermolysis of dicobalt octacarbonyl at the presence of Pd and Pt seeds and was tunable from 0.5 to 2.5 nm. <br /> <br /> The crystalline structure of the samples was characterized by transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDX), UV-VIS and electron-energy loss spectroscopy (EELS). SQUID magnetometry, x-ray magnetic circular dichroism (XMCD) and extended x-ray absorption fine structure (EXAFS) measurements gave information about the magnetic properties of the bimetallic systems and revealed their dependency on the particle size and the chemical composition. A high spin to orbital moments ratio µL/µS of 0.26±0.06 for Ag@Co and 0.22±0.05 for Pt@Co nanocrystals was observed at XMCD measurements due to the lowered dimensionality the investigated systems.