Search results for "Actant"

Functional characterisation of powders consisting of mixtures of glyceryl behenate and a non-ionic surfactant applied by hot-melt coating: lubricant …

2013

Solid-phase lubricants are routinely used in tablet manufacturing to reduce friction during the densification and ejection phases. However, two main challenges are commonly observed: a) poor blending of the lubricant with the other components; b) increased hydrophobicity of the mix. Hot-melt coating, wherein the substrate is coated with a composite lubricant consisting of glyceryl behenate and a non-ionic surfactant (polyethylene glycol behenate), offers a solution to these challenges. Comparative studies were undertaken using the composite lubricant in a hot-melt coating process and in a ‘standard’ physical blending method. This study shows that the addition of a surfactant to glyceryl beh…

Oil-in-Water fL Droplets by Interfacial Spontaneous Fragmentation and Their Electrical Characterization

2019

Inkjet printing is here employed for the first time as a method to produce femtoliter-scale oil droplets dispersed in water. In particular, picoliter-scale fluorinated oil (FC40) droplets are printed in the presence of perfluoro-1-octanol surfactant at a velocity higher than 5 m/s. Femtoliter-scale oil droplets in water are spontaneously formed through a fragmentation process at the water/air interface using minute amounts of nonionic surfactant (down to 0.003% v/v of Tween 80). This fragmentation occurs by a Plateau-Rayleigh mechanism at a moderately high Weber number (10(1)). A microfluidic chip with integrated microelectrodes allows droplets characterization in terms of number and diamet…

Influence of the Interlayer Space on the Water Oxidation Performance in a Family of Surfactant-Intercalated NiFe-Layered Double Hydroxides

2019

Layered double hydroxides (LDHs) are low dimensional materials that act as benchmark catalysts for the oxygen evolution reaction (OER). Many LDH properties affecting the OER have been studied to reach the optimal efficiency but no systematic studies concerning the influence of the interlayer space have been developed. In this context, these materials allow a large tunability in their chemical composition enabling the substitution of the interlayer anion and therefore modifying exclusively the basal space. Here, we synthesize by anion exchange reactions a surfactantintercalated family of NiFe-LDHs with increasing basal spacing ranging from 8.0 to 31.6 Å (one of the largest reported so far fo…

2014

NanosizedCeO2powders were synthesized via hydrothermal method with different types of surfactants (polyethylene glycol (PEG), cetyltrimethylammonium bromide (CTAB), and sodium dodecylbenzenesulfonate (SDBS)). X-ray diffraction, Raman spectroscopy, and transmission electron microscopy were utilized to characterize the phase structures and morphologies of the products. The sample with CTAB as surfactant (CeO2-C) has the largest specific surface area and the smallest particle size among these three samples. The humidity sensor fabricated byCeO2-C shows higher performance than those usedCeO2-P andCeO2-S. The impedance of theCeO2-C sensor decreases by about five orders of magnitude with relative…

Mammalian cell growth on gold nanoparticle-decorated substrates is influenced by the nanoparticle coating

2014

In this work, we study epithelial cell growth on substrates decorated with gold nanorods that are functionalized either with a positively charged cytotoxic surfactant or with a biocompatible polymer exhibiting one of two different end groups, resulting in a neutral or negative surface charge of the particle. Upon observation of cell growth for three days by live cell imaging using optical dark field microscopy, it was found that all particles supported cell adhesion while no directed cell migration and no significant particle internalization occurred. Concerning cell adhesion and spreading as compared to cell growth on bare substrates after 3 days of incubation, a reduction by 45% and 95%, …

Precipitation synthesis of magnetite Fe3O4 nanoflakes

2014

Precipitation can be applied to synthesize magnetite Fe3O4 nanoflakes in an ambient air atmosphere without using any surfactant, templates or special equipment. Magnetite nanoflakes were precipitated from only Fe2+ chloride solution without adding Fe3+. The formation of Fe3O4 nanoflakes is suggested to occur due to formation of an intermediate goethite phase, thus providing anisotropic crystal growth. Compared to other methods, the method presented here is fast and suitable for large scale synthesis.

The role of halide ions in the anisotropic growth of gold nanoparticles: a microscopic, atomistic perspective

2016

We provide a microscopic view of the role of halides in controlling the anisotropic growth of gold nanorods through a combined computational and experimental study. Atomistic molecular dynamics simulations unveil that Br− adsorption is not only responsible for surface passivation, but also acts as the driving force for CTAB micelle adsorption and stabilization on the gold surface in a facet-dependent way. The partial replacement of Br− by Cl− decreases the difference between facets and the surfactant density. Finally, in the CTAC solution, no halides or micellar structures protect the gold surface and further gold reduction should be uniformly possible. Experimentally observed nanoparticle'…

Surfactant-Assisted Synthesis of Mesoporous Alumina Showing Continuously Adjustable Pore Sizes

1999

Porous materials displaying tailor-made pore sizes and shapes are particularly interesting in a great variety of real and potential applications where molecular recognition is needed, such as shape-selective catalysis, molecular sieving, and selective adsorption. Classically, apart from silica, materials most commonly used for catalysis and catalyst supports have been those based on high surface aluminas, owing to their thermal, chemical, and mechanical stability and their low cost. Earlier aluminas with high surface areas (~500 m/g) had been prepared using structure-directing agents. However, they were X-ray amorphous materials and their porosity was purely textural, characterized by wide …

Synthesis and physico-chemical characterization of gold nanoparticles softly coated by AOT

2006

Size-controlled gold nanoparticles/surfactant stable systems were prepared by the combined action of the solvated metal atom dispersion (SMAD) technique and confinement in anhydrous sodium bis(2-ethylhexyl)sulfosuccinate (AOT) micellar solution. From liquid samples, by evaporation of the organic solvent, solid gold nanoparticle-surfactant liquid crystals composites were obtained. Sample characterization was performed by X-ray diffraction (SAXS and WAXS), XPS spectroscopy and UV-vis-NIR spectroscopy. All experimental data consistently revealed the coexistence of two gold nanoparticle size populations: bigger nanoparticles (size 20-50 angstrom) and smaller ones (size of few angstrom). The two…

Physico-chemical characterization of Pd nanoparticles synthesized in w/o microemulsions

1998

Abstract The long time stability of surfactant-coated Pd nanoparticles in w/o microemulsions has been investigated. It has been proven that in suitable conditions, the use of the functionalized surfactant Pd(AOT)2 allows to obtain very stable nanosized Pd particles and to finely control their average size.