8 research outputs found
Irreflexiva destrución de las obras de un sistema de transporte con características urbanas grandiosas
Impact of the particle diameter on ion cloud formation from gold nanoparticles in ICPMS
The unique capabilities
of microsecond dwell time (DT) single-particle inductively coupled
plasma mass spectrometry (spICPMS) were utilized to characterize the
cloud of ions generated from the introduction of suspensions of gold
nanoparticles (AuNPs) into the plasma. A set of narrowly distributed
particles with diameters ranging from 15.4 to 100.1 nm was synthesized
and characterized according to established protocols. Statistically
significant numbers of the short transient spICPMS events were evaluated
by using 50 μs DT for their summed intensity, maximum intensity,
and duration, of which all three were found to depend on the particle
diameter. The summed intensity increases from 10 to 1661 counts and
the maximum intensity from 6 to 309 counts for AuNPs with diameters
from 15.4 to 83.2 nm. The event duration rises from 322 to 1007 μs
upon increasing AuNP diameter. These numbers represent a comprehensive
set of key data points of the ion clouds generated in ICPMS from AuNPs.
The extension of event duration is of high interest to appoint the
maximum possible particle number concentration at which separation
of consecutive events in spICPMS can still be achieved. Moreover,
the combined evaluation of all above-mentioned ion cloud characteristics
can explain the regularly observed prolonged single-particle events.
The transport and ionization behavior of AuNPs in the ICP was also
computationally modeled to gain insight into the size-dependent signal
generation. The simulated data reveals that the plasma temperature,
and therefore the point of ionization of the particles, is the same
for all diameters. However, the maximum number density of Au+, as well as the extent of the ion cloud, depends on the particle
diameter, in agreement with the experimental data, and it provides
an adequate explanation for the observed ion cloud characteristics
Methods to improve microstructural properties of recycled concrete aggregate : a critical review
Recycled concrete aggregate is a demolition concrete waste, which could be an environmental-friendly building material and can be a serious contender for saving natural aggregate and reducing environmental pollution. Nevertheless, the use of the same is limited, as it has inferior qualities compared to virgin aggregate, such as low density, high porosity, high water absorption rate, micro cracks in residual mortar and at the interfacial transition zones. Thereby, the need of improving the properties of recycled aggregate is vital to enable a wider adoption of the same. This paper provides an insight into identifying knowledge gaps and as a critical review for the methods, technologies, its advantages and disadvantages for
improving the microstructural and mechanical properties of recycled aggregate, such as self-healing methods of re-hydration, bacterial and micro-encapsulation, sequential mixing approaches, removal of adhered mortar, permeation of solutions, coating with solutions and CO2 carbonation approaches. The existing studies to improve the properties of the recycled aggregate, are limited and the density improvement techniques by permeation of chemicals and/or reactions have only been superficially studied