The Experts below are selected from a list of 66351 Experts worldwide ranked by ideXlab platform
Arnd Pralle - One of the best experts on this subject based on the ideXlab platform.
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model driven optimization of magnetic anisotropy of exchange coupled core shell ferrite Nanoparticles for maximal hysteretic loss
Chemistry of Materials, 2015Co-Authors: Qian Zhang, Rahul Munshi, Iñaki Orue, Beatriz Pelaz, Katharina Ines Gries, Wolfgang J. Parak, Pablo Del Pino, Idoia Castellanosrubio, Arnd PralleAbstract:This study provides a guide to maximizing hysteretic loss by matching the design and synthesis of superparamagnetic Nanoparticles to the desired hyperthermia application. The maximal heat release from magnetic Nanoparticles to the environment depends on intrinsic properties of magnetic Nanoparticles (e.g., Size, magnetization, and magnetic anisotropy) and extrinsic properties of the applied fields (e.g., frequency and field strength). Often, the biomedical hyperthermia application limits flexibility in settings of many parameters (e.g., Nanoparticle Size and mobility, field strength, and frequency). We show that core–shell Nanoparticles combining a soft (Mn ferrite) and a hard (Co ferrite) magnetic material form a system in which the effective magnetic anisotropy can be easily tuned independently of the Nanoparticle Size. A theoretical framework to include the crystal anisotropy contribution of the Co ferrite phase to the Nanoparticle’s total anisotropy is developed. The experimental results confirm that ...
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Model Driven Optimization of Magnetic Anisotropy of Exchange-Coupled Core–Shell Ferrite Nanoparticles for Maximal Hysteretic Loss
2015Co-Authors: Qian Zhang, Idoia Castellanos-rubio, Rahul Munshi, Iñaki Orue, Beatriz Pelaz, Katharina Ines Gries, Wolfgang J. Parak, Pablo Del Pino, Arnd PralleAbstract:This study provides a guide to maximizing hysteretic loss by matching the design and synthesis of superparamagnetic Nanoparticles to the desired hyperthermia application. The maximal heat release from magnetic Nanoparticles to the environment depends on intrinsic properties of magnetic Nanoparticles (e.g., Size, magnetization, and magnetic anisotropy) and extrinsic properties of the applied fields (e.g., frequency and field strength). Often, the biomedical hyperthermia application limits flexibility in settings of many parameters (e.g., Nanoparticle Size and mobility, field strength, and frequency). We show that core–shell Nanoparticles combining a soft (Mn ferrite) and a hard (Co ferrite) magnetic material form a system in which the effective magnetic anisotropy can be easily tuned independently of the Nanoparticle Size. A theoretical framework to include the crystal anisotropy contribution of the Co ferrite phase to the Nanoparticle’s total anisotropy is developed. The experimental results confirm that this framework predicts the hysteretic heating loss correctly when including nonlinear effects in an effective susceptibility. Hence, we provide a guide on how to characterize the magnetic anisotropy of core–shell magnetic Nanoparticles, model the expected heat loss, and thereby syntheSize tuned Nanoparticles for a particular biomedical application
Qian Zhang - One of the best experts on this subject based on the ideXlab platform.
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model driven optimization of magnetic anisotropy of exchange coupled core shell ferrite Nanoparticles for maximal hysteretic loss
Chemistry of Materials, 2015Co-Authors: Qian Zhang, Rahul Munshi, Iñaki Orue, Beatriz Pelaz, Katharina Ines Gries, Wolfgang J. Parak, Pablo Del Pino, Idoia Castellanosrubio, Arnd PralleAbstract:This study provides a guide to maximizing hysteretic loss by matching the design and synthesis of superparamagnetic Nanoparticles to the desired hyperthermia application. The maximal heat release from magnetic Nanoparticles to the environment depends on intrinsic properties of magnetic Nanoparticles (e.g., Size, magnetization, and magnetic anisotropy) and extrinsic properties of the applied fields (e.g., frequency and field strength). Often, the biomedical hyperthermia application limits flexibility in settings of many parameters (e.g., Nanoparticle Size and mobility, field strength, and frequency). We show that core–shell Nanoparticles combining a soft (Mn ferrite) and a hard (Co ferrite) magnetic material form a system in which the effective magnetic anisotropy can be easily tuned independently of the Nanoparticle Size. A theoretical framework to include the crystal anisotropy contribution of the Co ferrite phase to the Nanoparticle’s total anisotropy is developed. The experimental results confirm that ...
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Model Driven Optimization of Magnetic Anisotropy of Exchange-Coupled Core–Shell Ferrite Nanoparticles for Maximal Hysteretic Loss
2015Co-Authors: Qian Zhang, Idoia Castellanos-rubio, Rahul Munshi, Iñaki Orue, Beatriz Pelaz, Katharina Ines Gries, Wolfgang J. Parak, Pablo Del Pino, Arnd PralleAbstract:This study provides a guide to maximizing hysteretic loss by matching the design and synthesis of superparamagnetic Nanoparticles to the desired hyperthermia application. The maximal heat release from magnetic Nanoparticles to the environment depends on intrinsic properties of magnetic Nanoparticles (e.g., Size, magnetization, and magnetic anisotropy) and extrinsic properties of the applied fields (e.g., frequency and field strength). Often, the biomedical hyperthermia application limits flexibility in settings of many parameters (e.g., Nanoparticle Size and mobility, field strength, and frequency). We show that core–shell Nanoparticles combining a soft (Mn ferrite) and a hard (Co ferrite) magnetic material form a system in which the effective magnetic anisotropy can be easily tuned independently of the Nanoparticle Size. A theoretical framework to include the crystal anisotropy contribution of the Co ferrite phase to the Nanoparticle’s total anisotropy is developed. The experimental results confirm that this framework predicts the hysteretic heating loss correctly when including nonlinear effects in an effective susceptibility. Hence, we provide a guide on how to characterize the magnetic anisotropy of core–shell magnetic Nanoparticles, model the expected heat loss, and thereby syntheSize tuned Nanoparticles for a particular biomedical application
Gabor A Somorjai - One of the best experts on this subject based on the ideXlab platform.
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effects of Nanoparticle Size and metal support interactions in pt catalyzed methanol oxidation reactions in gas and liquid phases
Catalysis Letters, 2014Co-Authors: Hailiang Wang, Andras Sapi, Fudong Liu, Gabor A SomorjaiAbstract:We compare catalytic methanol oxidation reactions in the gas and liquid phases by focusing on the kinetic effects of platinum Nanoparticle Size and metal/ support interactions. Under the reaction conditions at 60 C, methanol can be oxidized to multiple products including carbon dioxide (full-oxidation product), formal- dehyde (partial-oxidation product) and methyl formate (partial-oxidation and coupling product). We use 2, 4, 6 and 8 nm platinum Nanoparticles supported on mesoporous silica as catalysts to study the Size effect, and 2.5 nm platinum Nanoparticles supported on mesoporous SiO2, Co3O4, MnO2 ,F e 2O3, NiO and CeO2 to study the metal/ oxide interface effect. We find that all three products are formed with comparable selectivities in the gas phase, but in the liquid phase formaldehyde is the dominant product. While the influence of Size on activity is not substantial in the gas phase, the liquid-phase reaction rates monotonically increase by a factor of 6 in the Size range of 2-8 nm. The reaction rates in the gas phase are dramatically affected by the strong interactions between the platinum Nanoparticles and transition metal oxide supports. While the Pt/MnO2 is 135 times less active, the Pt/CeO2 is 12 times more active, both compared to the Pt/SiO2. However in the liquid phase, the support effect is less significant, with the most active catalyst Pt/MnO2 exhibiting an enhancement factor of 2.5 compared to the Pt/SiO2. Our results suggest that the kinetic effects of platinum Nanoparticle Size and metal/ support interactions can be totally different between the solid/gas and solid/liquid interfaces even for the same chemical reaction.
Mostafa A Elsayed - One of the best experts on this subject based on the ideXlab platform.
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effect of colloidal catalysis on the Nanoparticle Size distribution dendrimer pd vs pvp pd Nanoparticles catalyzing the suzuki coupling reaction
Journal of Physical Chemistry B, 2004Co-Authors: Radha Narayanan, Mostafa A ElsayedAbstract:A comparison of the stability and catalytic activity of PAMAM−OH generation 4 dendrimer−Pd Nanoparticles (1.3 ± 0.1 nm) with the previously studied PVP−Pd Nanoparticles (2.1 ± 0.1 nm) in the Suzuki coupling reaction between phenylboronic acid and iodobenzene is conducted. After the first cycle, the average Size of the PVP−Pd Nanoparticles increases by 38% and the dendrimer−Pd Nanoparticles increases by 54%. After the second cycle, the PVP−Pd Nanoparticles decrease in Size by 24% whereas the dendrimer−Pd Nanoparticles continue to increase in Size by 35%. The strong encapsulating action of the PAMAM−OH generation 4 dendrimer−Pd Nanoparticles could make the rate of conversion to the full Nanoparticle Size slow, resulting in a large excess Pd metal atom concentration in solution, resulting in the continuous growth of the Nanoparticles during the catalytic reaction. The effect of the individual reactants on the stability of the dendrimer−Pd Nanoparticles has also been investigated and found to be similar to th...
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effect of catalytic activity on the metallic Nanoparticle Size distribution electron transfer reaction between fe cn 6 and thiosulfate ions catalyzed by pvp platinum Nanoparticles
Journal of Physical Chemistry B, 2003Co-Authors: Radha Narayanan, Mostafa A ElsayedAbstract:The electron-transfer reaction between hexacyanoferrate(III) ions and thiosulfate ions is known to be catalyzed by platinum Nanoparticles. In the present study, the stability and catalytic activity of the PVP−Pt Nanoparticle during its catalytic function for this electron-transfer reaction is studied. The stability of the Nanoparticles after various perturbations was assessed using TEM, and the kinetics of the reaction was followed using absorption spectroscopy. The studies were conducted on four different concentrations of PVP−Pt Nanoparticles. It was found that the average Size and width of the PVP−Pt Nanoparticles decrease slightly after the first and second cycles of the electron-transfer reaction. The Size and Size distribution width do not change in the presence of only the thiosulfate reactant, whereas the presence of only the hexacyanoferrate reactant results in a reduction of the Nanoparticle Size. The reduction in the Nanoparticle Size in the presence of hexacyanoferrate(III) ions is proposed to...
Jonathan S Dordick - One of the best experts on this subject based on the ideXlab platform.
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silica Nanoparticle Size influences the structure and enzymatic activity of adsorbed lysozyme
Langmuir, 2004Co-Authors: Alexey A Vertegel, Richard W Siegel, Jonathan S DordickAbstract:Adsorption of chicken egg lysozyme on silica Nanoparticles of various diameters has been studied. Special attention has been paid to the effect of Nanoparticle Size on the structure and function of the adsorbed protein molecules. Both adsorption patterns and protein structure and function are strongly dependent on the Size of the Nanoparticles. Formation of molecular complexes is observed for adsorption onto 4-nm silica. True adsorptive behavior is evident on 20- and 100-nm particles, with the former resulting in monolayer adsorption and the latter yielding multilayer adsorption. A decrease in the solution pH results in a decrease in lysozyme adsorption. A change of protein structure upon adsorption is observed, as characterized by a loss in α-helix content, and this is strongly dependent on the Size of the Nanoparticle and the solution pH. Generally, greater loss of α helicity was observed for the lysozyme adsorbed onto larger Nanoparticles under otherwise similar conditions. The activity of lysozyme ads...
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silica Nanoparticle Size influences the structure and enzymatic activity of adsorbed lysozyme
Langmuir, 2004Co-Authors: Alexey A Vertegel, Richard W Siegel, Jonathan S DordickAbstract:Adsorption of chicken egg lysozyme on silica Nanoparticles of various diameters has been studied. Special attention has been paid to the effect of Nanoparticle Size on the structure and function of the adsorbed protein molecules. Both adsorption patterns and protein structure and function are strongly dependent on the Size of the Nanoparticles. Formation of molecular complexes is observed for adsorption onto 4-nm silica. True adsorptive behavior is evident on 20- and 100-nm particles, with the former resulting in monolayer adsorption and the latter yielding multilayer adsorption. A decrease in the solution pH results in a decrease in lysozyme adsorption. A change of protein structure upon adsorption is observed, as characterized by a loss in alpha-helix content, and this is strongly dependent on the Size of the Nanoparticle and the solution pH. Generally, greater loss of alpha helicity was observed for the lysozyme adsorbed onto larger Nanoparticles under otherwise similar conditions. The activity of lysozyme adsorbed onto silica Nanoparticles is lower than that of the free protein, and the fraction of activity lost correlates well with the decrease in alpha-helix content. These results indicate that the Size of the Nanoparticle, perhaps because of the contributions of surface curvature, influences adsorbed protein structure and function.
