Core–shell or fused-core particles

2015 ◽  
pp. 136-150
Author(s):  
Evgenia Makrygianni ◽  
Victoria Samanidou
Keyword(s):  
Core Shell ◽  
Core Particles

scholarly journals Synthesis and characterization of mesoporous silica core-shell particles

2010 ◽  
Vol 4 (2) ◽  
pp. 81-85 ◽  
Author(s):  
Milan Nikolic ◽  
Konstantinos Giannakopoulos ◽  
Vladimir Srdic
Keyword(s):  
Sodium Silicate Solution ◽  
Silicate Solution ◽  
Silica Particles ◽  
Core Shell ◽  
Functionalized Silica ◽  
Silica Core ◽  
Shell Particles ◽  
Average Size ◽  
Core Particles

Core-shell particles were formed by deposition of primary silica particles synthesized from sodium silicate solution on functionalized silica core particles (having size of ~0.5 ?m) prepared by hydrolysis and condensation of tetraethylortosilicate. The obtained mesoporous shell has thickness of about 60 nm and consists of primary silica particles with average size of ~21 nm. Scanning electron microscopy and zeta potential measurements showed that continuous silica shell exists around functionalized core particles which was additionally proved by FTIR and TEM results.

scholarly journals Effect of reaction time on formation of silica core/shell particles

2015 ◽  
Vol 9 (4) ◽  
pp. 209-214 ◽  
Author(s):  
Milan Nikolic ◽  
Radoslav Filipovic ◽  
Slobodanka Stanojevic-Nikolic
Keyword(s):  
Reaction Time ◽  
Mesoporous Silica ◽  
Silica Nanoparticles ◽  
Sodium Silicate ◽  
Sodium Silicate Solution ◽  
Silicate Solution ◽  
Core Shell ◽  
Silica Core ◽  
Shell Particles ◽  
Core Particles

The silica core/shell nanostructures were prepared by a wet-chemical process. Silica core particles were prepared by hydrolysis and condensation of tetraethylorthosilicate. The obtained particles (average size ~0.4 ?m) were used as templates for assembling of silica nanoparticles generated from highly basic sodium silicate solution. The silica core particles were functionalized with 3-aminopropyltriethoxysilane (APTES) to allow electrostatic assembling of silica nanoparticles on the surface of silica core particles. In order to find the optimal conditions for synthesis of silica core/shell particles with mesoporous shells, the effect of reaction time on formation of silica nanoparticles was investigated. The effect of process parameters on generation and aggregation of silica nanoparticles prepared from highly basic sodium silicate solution was also investigated. It was shown that the size of silica nanoparticles and tendency towards aggregation increase with increasing the reaction time and temperature. These behaviours were reflected on the formation of mesoporous silica shell around silica core particles. Thin and uniform mesoporous silica layers were obtained if reaction times were kept short. When the reaction time was prolonged, the thicker and non-uniform shells were obtained.

Nanocomposite particles for the preparation of advanced nanomaterials

1997 ◽  
Vol 501 ◽  
Author(s):  
P. Somasundaran ◽  
T. Chen
Keyword(s):  
Shell Structure ◽  
Advanced Technology ◽  
Core Shell ◽  
Nanocomposite Particles ◽  
The Core ◽  
Micron Size ◽  
Core Shell Structure ◽  
Shell Particles ◽  
Nano Size ◽  
Core Particles

ABSTRACTNew composites based on nano-size particles provide a promising route to the fabrication of novel materials for advanced technology applications. To produce desired materials, it is important to control the composition and distribution of nanoclusters within the bulk or surface coating of nanostructured materials. Towards this purpose, we have developed a novel method of processing nanocomposite materials utilizing colloidal chemistry techniques to tailor their microstructure. Unique composite aggregates of nanoparticles with a core-shell structure were prepared using a special scheme ofcontrolledpolymer adsorption. Polymers which specifically adsorb on both nano- and micron- size particles are used as tethers to enable desired coating of the later particles with the former and to enhance the cluster integrity. Nanocomposite particles consisting of micron-size alumina or silicon nitride as cores and nano-size alumina, titania, or iron oxide as shell particles have been successfully prepared using this process. The surface charge of the core particles is reversed after the adsorption of polyacrylic acid polymers. This promotes the interaction between the core and the shell particles and therefore nanoparticles added subsequently to the core particle suspension coat on core particles by electrostatic as well as possibly hydrogen bonding bridging mechanisms. Success of the process depends to a large extent on the absence of homoflocculation of nanoparticles and this is achieved by removing all the unadsorbed free polymers from the bulk solution before introducing them to coat on the polymer coated core particles. Coating itself is estimated by monitoring change in the zeta potential of core-shell structure. The coating scheme as well as the characterization of these nanocomposite particles are discussed in detail. This processing scheme provides a simple way for the preparation of both bulk and surface coatings with these engineered nanostructured particles as building blocks.

scholarly journals 3D-ordered carbon materials by melt-shear organization for tailor-made hybrid core–shell polymer particle architectures

2016 ◽  
Vol 4 (18) ◽  
pp. 3976-3986 ◽  
Author(s):  
S. Vowinkel ◽  
C. G. Schäfer ◽  
G. Cherkashinin ◽  
C. Fasel ◽  
F. Roth ◽  
...  
Keyword(s):  
Thermal Treatment ◽  
Carbon Materials ◽  
Polymer Particle ◽  
Core Shell ◽  
Porous Films ◽  
Silica Core ◽  
Core Particles

The melt-shear organization technique for tailor-made polystyrene-co-polyacrylonitrile (PSAN) shell and silica core particles is investigated yielding easy-scalable carbonaceous porous films after etching and appropriate thermal treatment.

Al/Al2O3 Core-Shell Particles Synthesized by Wet-Chemical Based Route

2006 ◽  
Vol 313 ◽  
pp. 63-68 ◽  
Author(s):  
Hua Min Kou ◽  
Jing Kun Guo ◽  
Jing Wang ◽  
Yu Bai Pan
Keyword(s):  
Composite Materials ◽  
Composite Particles ◽  
Core Shell ◽  
Coating Process ◽  
Coated Particles ◽  
Wet Chemical ◽  
Shell Particles ◽  
Core Particles

Coating process is attracting more and more attention in the preparation of composite materials mainly due to its predominance in the improvement of the uniformity for different phases. The formation of nanosize alumina shells on the aluminum core particles by a wet-chemical based route was investigated and the composite particles were characterized using TG/DSC, XRD, SEM, TEM, XPS. An enhancement of cermet properties can be expected by using these coated particles as initial powders.

Imaging of ribosomal RNA-protein interactions by dark-field STEM

1989 ◽  
Vol 47 ◽  
pp. 250-251
Author(s):  
M. Boublik ◽  
V. Mandiyan ◽  
S. Tumminia ◽  
J.F. Hainfeld ◽  
J.S. Wall
Keyword(s):  
Nucleic Acid ◽  
16S Rrna ◽  
Dark Field ◽  
Radius Of Gyration ◽  
Central Domain ◽  
The Core ◽  
16S Rna ◽  
30S Subunit ◽  
Core Particles

Success in protein-free deposition of native nucleic acid molecules from solutions of selected ionic conditions prompted attempts for high resolution imaging of nucleic acid interactions with proteins, not attainable by conventional EM. Since the nucleic acid molecules can be visualized in the dark-field STEM mode without contrasting by heavy atoms, the established linearity between scattering cross-section and molecular weight can be applied to the determination of their molecular mass (M) linear density (M/L), mass distribution and radius of gyration (RG). Determination of these parameters promotes electron microscopic imaging of biological macromolecules by STEM to a quantitative analytical level. This technique is applied to study the mechanism of 16S rRNA folding during the assembly process of the 30S ribosomal subunit of E. coli. The sequential addition of protein S4 which binds to the 5'end of the 16S rRNA and S8 and S15 which bind to the central domain of the molecule leads to a corresponding increase of mass and increased coiling of the 16S rRNA in the core particles. This increased compactness is evident from the decrease in RG values from 114Å to 91Å (in “ribosomal” buffer consisting of 10 mM Hepes pH 7.6, 60 mM KCl, 2 m Mg(OAc)2, 1 mM DTT). The binding of S20, S17 and S7 which interact with the 5'domain, the central domain and the 3'domain, respectively, continues the trend of mass increase. However, the RG values of the core particles exhibit a reverse trend, an increase to 108Å. In addition, the binding of S7 leads to the formation of a globular mass cluster with a diameter of about 115Å and a mass of ∽300 kDa. The rest of the mass, about 330 kDa, remains loosely coiled giving the particle a “medusa-like” appearance. These results provide direct evidence that 16S RNA undergoes significant structural reorganization during the 30S subunit assembly and show that its interactions with the six primary binding proteins are not sufficient for 16S rRNA coiling into particles resembling the native 30S subunit, contrary to what has been reported in the literature.

A crystalline–amorphous Ni–Ni(OH)2 core–shell catalyst for the alkaline hydrogen evolution reaction

2020 ◽  
Vol 8 (44) ◽  
pp. 23323-23329
Author(s):  
Jing Hu ◽  
Siwei Li ◽  
Yuzhi Li ◽  
Jing Wang ◽  
Yunchen Du ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Electrocatalytic Activity ◽  
Core Shell ◽  
Alkaline Conditions

Crystalline–amorphous Ni–Ni(OH)2 core–shell assembled nanosheets exhibit outstanding electrocatalytic activity and stability for hydrogen evolution under alkaline conditions.

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