Reversible formation of gold nanoparticle–surfactant composite assemblies for the preparation of concentrated colloidal solutions

We have developed a simple method for the preparation of nearly mono-dispersed stable gold colloids with a fairly high concentration using a two step procedure. First we synthesize citrate capped gold nanoparticles and then exchange the citrate ions with triethyleneglycolmono-11-mercaptoundecylether (EGMUDE). This leads to the immediate precipitation and formation of composite assemblies. The gold nanoparticles were successfully self-redispersed after a few days. The prepared gold colloid can be easily concentrated up to 20 times by separation of the flocculated part. UV-visible spectra, transmission electron microscopy (TEM), and dynamic light scattering (DLS) were used to characterize the products thus formed

Electroluminescent device

The invention concerns a electroluminescent device with a multilayer structure comprising: i) a first electrode including a layer, consisting of a transparent or translucent conductive material selected among metal oxides and metal nitrides, said layer being deposited on a transparent support, consisting of a glass, silicon, alumina plate, or a polymer sheet; ii) a second electrode; iii) a layer, arranged between the two electrodes, comprising a semiconductor and electroluminescent solid organic substance, said layer being optionally bordered with one or several intermediate layers, consisting of electrocatalysts; and iv) a layer with monomolecular structure, arranged between the layer consisting of the conductive material and the layer consisting of the electroluminescent substance. Said device is furher characterised in that said layer consists of a dipolar organic compound whereof the structure has an electronic system pi, a functional group, vicinal or not of the electronic system pi. Moreover, the dipolar organic compound is chemically bound by the functional group to the conductive material and has chemical affinity for the organic electroluminescent substance

Pigments based on silica-coated gold nanorods: Synthesis, colouring strength, functionalisation, extrusion, thermal stability and colour evolution

The intense plasmon absorption bands of gold nanorods (GNRs) with peak extinction coefficients up to 6.4 x 109 M-1 cm-1 as well as their expected high stability make GNRs promising candidates for the colouration of bulk materials. The comparison of the integrated absorption in the visible region of GNRs with those of commercial organic pigments shows that the colouring strength of GNRs is 4 to 8 times higher. In order to improve their stability, GNRs were encapsulated in a silica shell of around 15 nm thickness using an optimized Stöber method. The silica surface was modified with octadecylsilane to enable their dispersion in non-polar media. Different plastics were successfully coloured with a tiny quantity of bare and functionalised GNRs@SiO2. These rods were homogeneously dispersed using extrusion. The shape of the rods was effectively stabilised by the silica shell at high temperature during the extrusion process. Surprisingly, a slight modification of the rods colour was observed due to a decrease of the refractive index in the mesoporous silica shell. However, this effect is greatly limited after the functionalisation

On the Thermal Conductivity of Gold Nanoparticle Colloids

Nanofluids (colloidal suspensions of nanoparticles) have been reported to display significantly enhanced thermal conductivities relative to those of conventional heat transfer fluids, also at low concentrations well below 1% per volume (Putnam, S. A., et at. J. Appl. Phys. 2006, 99, 084308; Liu, M.-S. L., et al. Int. J. Heat Mass Transfer. 2006, 49; Patel, H. E., et al. Appl. Phys. Lett. 2003, 83, 2931−2933). The purpose of this paper is to evaluate the effect of the particle size, concentration, stabilization method and particle clustering on the thermal conductivity of gold nanofluids. We synthesized spherical gold nanoparticles of different size (from 2 to 45 nm) and prepared stable gold colloids in the range of volume fraction of 0.00025−1%. The colloids were inspected by UV−visible spectroscopy, transmission electron microscope (TEM) and dynamic light scattering (DLS). The thermal conductivity has been measured by the transient hot-wire method (THW) and the steady state parallel plate method (GAP method). Despite a significant search in parameter space no significant anomalous enhancement of thermal conductivity was observed. The highest enhancement in thermal conductivity is 1.4% for 40 nm sized gold particles stabilized by EGMUDE (triethyleneglycolmono-11-mercaptoundecylether) and suspended in water with a particle-concentration of 0.11 vol%

Erratum to: Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition) (Autophagy, 12, 1, 1-222, 10.1080/15548627.2015.1100356

non present