green synthesis of nanoparticles, as fundamental building blocks of nanotechnology, has recently attracted considerable attention. silver nanoparticles have unique physiochemical, biological and environmental properties which make them useful in a wide range of applications. in the present paper we report our research results on biosynthesis of silver nanoparticles from silver precursor using m...

Using transmittance electron microscopy, fluorescence and polarizing optical microscopy, optical spectroscopy, and fluorescent correlation spectroscopy, it was shown that CdSe/ZnS quantum dots coated with a specifically designed surfactant were readily dispersed in nematic liquid crystal (LC) to form stable colloids. The mixture of an alkyl phosphonate and a dendritic surfactant, where the cons...

Silver colloids of uniform shape and size are prepared by a two-step reduction. Small silver particles form initially by the rapid reduction of silver nitrate with sodium citrate at 100°C and then grow at 92°C. The reaction processes and resulting silver colloids are characterized by transmission electron microscopy, ultraviolet-visible absorption spectrophotometry, zeta-potential measurements,...

Abstract A sets of sand column experiments were conducted to investigate the transport and deposition of colloids in water-saturated porous media, and the mechanism of the permeability reduced by transport and deposition of colloids are discussed. The research results show that the breakthrough curves of colloid transport in water-bearing media presented as three stages: “not-yet-breakthrough”,...

We study catalytic Janus particles and Escherichia coli bacteria swimming in a two-dimensional colloidal crystal. The Janus particles orbit individual colloids and hop between colloids stochastically, with a hopping rate that varies inversely with fuel (hydrogen peroxide) concentration. At high fuel concentration, these orbits are stable for 100s of revolutions, and the orbital speed oscillates...

The addition of enough non-adsorbing polymers to an otherwise stable colloidal suspension gives rise a variety phase behaviors and kinetic arrest due the depletion attraction induced between colloids by polymers. We report study these phenomena in two-dimensional layer colloids. three-dimensional phenomenology crystal–fluid coexistence is reproduced, but gelation takes novel form, which strands...

We systematically study the properties of dispersions of iron-based colloids synthesized in a broad size range by thermal decomposition of ironcarbonyl using different stabilizing surfactants. The synthesis results in stable dispersions of monodomain magnetic colloids. Our particles appear to consist of an amorphous Fe(0.75)C(0.25) alloy. Sizes of particles coated with modified polyisobutene or...

Motivated by recent experiments on colloidal systems with competing attractive and repulsive interactions, we simulate a two-dimensional system of colloids with competing interactions that can undergo fragmentation. In the absence of any other confining potential, the colloids can form stable clusters depending on the strength of the short range attractive term. By suddenly changing the strengt...

The liquid-liquid phase separation of a binary solvent can be arrested by colloidal particles trapped at the interface [K. Stratford, Science 309, 2198 (2005)]. We show experimentally that the colloidal network so formed can remain stable after fully remixing the liquids, creating a new type of gel in which colloids in a single-phase solvent have locally planar coordination. We argue that this ...

Complexation of Zr(IV) by humic acid (HA) and polyacrylic acid (PAA) is investigated from the point of view of the organic ligand. STXM spectromicroscopy and C 1s-NEXAFS point to different interaction mechanisms between Zr(IV) cations and oxo/hydroxo colloids and PAA. Under conditions where the metal aquo ion is stable, strong complexes are formed. In contrast, unspecific surface coating is ide...