31 research outputs found
Versailles project on advanced materials and standards (VAMAS) interlaboratory study on measuring the number concentration of colloidal gold nanoparticles
We describe the outcome of a large international interlaboratory study of the measurement of particle number concentration of colloidal nanoparticles, project 10 of the technical working area 34, "Nanoparticle Populations" of the Versailles Project on Advanced Materials and Standards (VAMAS). A total of 50 laboratories delivered results for the number concentration of 30 nm gold colloidal nanoparticles measured using particle tracking analysis (PTA), single particle inductively coupled plasma mass spectrometry (spICP-MS), ultraviolet-visible (UV-Vis) light spectroscopy, centrifugal liquid sedimentation (CLS) and small angle X-ray scattering (SAXS). The study provides quantitative data to evaluate the repeatability of these methods and their reproducibility in the measurement of number concentration of model nanoparticle systems following a common measurement protocol. We find that the population-averaging methods of SAXS, CLS and UV-Vis have high measurement repeatability and reproducibility, with between-labs variability of 2.6%, 11% and 1.4% respectively. However, results may be significantly biased for reasons including inaccurate material properties whose values are used to compute the number concentration. Particle-counting method results are less reproducibile than population-averaging methods, with measured between-labs variability of 68% and 46% for PTA and spICP-MS respectively. This study provides the stakeholder community with important comparative data to underpin measurement reproducibility and method validation for number concentration of nanoparticles
Versailles project on advanced materials and standards (VAMAS) interlaboratory study on measuring the number concentration of colloidal gold nanoparticles
We describe the outcome of a large international interlaboratory study of the measurement of particle number concentration of colloidal nanoparticles, project 10 of the technical working area 34, "Nanoparticle Populations" of the Versailles Project on Advanced Materials and Standards (VAMAS). A total of 50 laboratories delivered results for the number concentration of 30 nm gold colloidal nanoparticles measured using particle tracking analysis (PTA), single particle inductively coupled plasma mass spectrometry (spICP-MS), ultraviolet-visible (UV-Vis) light spectroscopy, centrifugal liquid sedimentation (CLS) and small angle X-ray scattering (SAXS). The study provides quantitative data to evaluate the repeatability of these methods and their reproducibility in the measurement of number concentration of model nanoparticle systems following a common measurement protocol. We find that the population-averaging methods of SAXS, CLS and UV-Vis have high measurement repeatability and reproducibility, with between-labs variability of 2.6%, 11% and 1.4% respectively. However, results may be significantly biased for reasons including inaccurate material properties whose values are used to compute the number concentration. Particle-counting method results are less reproducibile than population-averaging methods, with measured between-labs variability of 68% and 46% for PTA and spICP-MS respectively. This study provides the stakeholder community with important comparative data to underpin measurement reproducibility and method validation for number concentration of nanoparticles
Versailles project on advanced materials and standards (VAMAS) interlaboratory study on measuring the number concentration of colloidal gold nanoparticles
We describe the outcome of a large international interlaboratory study of the measurement of particle number concentration of colloidal nanoparticles, project 10 of the technical working area 34, "Nanoparticle Populations" of the Versailles Project on Advanced Materials and Standards (VAMAS). A total of 50 laboratories delivered results for the number concentration of 30 nm gold colloidal nanoparticles measured using particle tracking analysis (PTA), single particle inductively coupled plasma mass spectrometry (spICP-MS), ultraviolet-visible (UV-Vis) light spectroscopy, centrifugal liquid sedimentation (CLS) and small angle X-ray scattering (SAXS). The study provides quantitative data to evaluate the repeatability of these methods and their reproducibility in the measurement of number concentration of model nanoparticle systems following a common measurement protocol. We find that the population-averaging methods of SAXS, CLS and UV-Vis have high measurement repeatability and reproducibility, with between-labs variability of 2.6%, 11% and 1.4% respectively. However, results may be significantly biased for reasons including inaccurate material properties whose values are used to compute the number concentration. Particle-counting method results are less reproducibile than population-averaging methods, with measured between-labs variability of 68% and 46% for PTA and spICP-MS respectively. This study provides the stakeholder community with important comparative data to underpin measurement reproducibility and method validation for number concentration of nanoparticles
data set for "3D calcite heterostructures for dynamic and deformable mineralized matrices"
data set for "3D calcite heterostructures for dynamic and deformable mineralized matrices
Bioinspired Morphogenesis of Highly Intricate and Symmetric Silica Nanostructures
Biosilification is of interest due to its capability
to produce
a highly intricate structure under environmentally friendly conditions.
Despite the considerable effort that has been devoted toward biomimetic
silification, the synthesis of highly complex silica structures, as
found in the structures of diatom cell walls, is still in its infancy.
Here, we report the bioinspired fabrication of well-organized and
symmetric silica nanostructured networks, involving phase separation
and silicic acid polymerization processes, in analogy to the morphogenesis
of diatom cell walls. Our approach exploits self-assembled silica
spheres as a self-source of the silicic acids as well as scaffolds
that, interplayed with droplets of ammonium hexafluorosilicate, direct
the site-specific silification. Moreover, we have achieved multiple
morphological evolutions with subtle changes in the process, which
demonstrates exquisite levels of control over silica morphogenesis
Direct Synthesis of Graphene Meshes and Semipermanent Electrical Doping
Here we describe a new method for
the direct patterned synthesis
of graphene meshes on Cu foils that use self-assembled silica sphere
arrays as growth masks. Structural analyses based on electron microscopy
and Raman spectroscopy showed that the graphene meshes are mostly
single- or double-layer necks with empty holes that have abrupt edges.
On the basis of experimental observations, we proposed the model illustrating
the dissociation of carbon atoms at the Cu/silica interface through
catalytic hydrogenation of the graphene lattice. Moreover, our approach
can minimize problems associated with the graphene etching process,
including contamination and exposure to reactive plasma. This enables
stable electronic doping through covalent CâN bonds at the
edges of graphene meshes