2 research outputs found
Molecular Orientational Order of Nitroxide Radicals in Liquid Crystalline Media
The
orientational distribution of a set of stable nitroxide radicals
in aligned liquid crystals 5CB (nematic) and 8CB (smectic A) was studied
in detail by numerical simulation of EPR spectra. The order parameters
up to the 10th rank were measured. The directions of the principal
orientation axes of the radicals were determined. It was shown that
the ordering of the probe molecules is controlled by their interaction
with the matrix molecules more than the inherent geometry of the probes
themselves. The rigid fused phenanthrene-based (A5) and 2-azaphenalene
(A4) nitroxides as well as the rigid core elongated C11 and 5α-cholestane
(CLS) nitroxides were found to be most sensitive to the orientation
of the liquid crystal matrixes
Influence of Fuel Molecular Structure on the Volatility and Oxidative Potential of Biodiesel Particulate Matter
We
have studied the effect of chemical composition of biodiesel
fuel on the physical (volatility) and chemical (reactive oxygenated
species concentration) properties of nano particles emitted from a
modern common-rail diesel engine. Particle emissions from the combustion
of four biodiesels with controlled chemical compositions and different
varying unsaturation degrees and carbon-chain lengths, together with
a commercial diesel, were tested and compared in terms of volatility
of particles and the amount of reactive oxygenated species carried
by particles. Different blends of biodiesel and petro diesel were
tested at several engine loads and speeds. We have observed that more
saturated fuels with shorter carbon chain lengths result in lower
particle mass but produce particles that are more volatile and also
have higher levels of Reactive Oxygen Species. This highlights the
importance of taking into account metrics that are relevant from the
health effects point of view when assessing emissions from new fuel
types