1. Magnetic Particles: Preparation, Properties and Applications.- 1 Introduction.- 2 Preparation.- 3 Properties of Magnetic Particles.- 4 Applications.- References.- 2. Maghemite (?-Fe2O3): A Versatile Magnetic Colloidal Material.- 1 Introduction.- 2 Synthesis.- 3 Crystal Structure and Cation Ordering.- 4 Colloidal Properties.- 5 Magnetic Properties.- 6 ?-Fe2O3 Nanocomposites.- References.- 3. Dynamics of Adsorption and Oxidation of Organic Molecules on Illuminated Titanium Dioxide Particles Immersed in Water.- 1 Introduction.- 2 One-Electron Oxidations, HS + hvb+ ? P + H+.- 3 One-Electron Oxidations of Substrates that Form Two Different Surface Complexes, =Ti-S1 and =Ti-S2.- 4 Two-Electron Oxidations, HS ? HP + 2H+ + 2e-.- 5 Oxidation of Mixtures of Two Organic Compounds, HS ? HP+ + e-, and HS' ? HP' + + e~.- 6 Reactions Mediated by OH* Radicals.- 7 Electron Injection in the Conduction Band (Photo-Electrochemical Experiments).- 8 Potential Dependence of the Rate Constants in Photo-Electrochemical Experiments.- 9 Photo-Oxidations in the Presence of Dissolved Oxidants (Dioxygen, etc.).- 10 Conclusions.- References.- 4. Colloidal Aggregations in Two-Dimensions.- 1 Introduction.- 2 Theory and Simulation of Colloidal Aggregation in 2-D.- 3 Experimental Study of Two-Dimensional Aggregation.- 4 Colloidal Stability and Interactions at Colloidal Monolayers.- 5 Global Analysis of the Two-Dimensional Aggregation.- Appendix: Notation.- References.- 5. Kinetics of Particle and Protein Adsorption.- 1 Introduction.- 2 Interactions—Driving Forces of Adsorption.- 3 Linear Adsorption Regimes.- 4 Non-Linear Adsorption Regimes.- 5 Experimental Evidences.- 6 Concluding Remarks.- Appendix: List of Symbols.- References.