The Cyprus Institute

About: The Cyprus Institute is a other organization based out in Nicosia, Cyprus. It is known for research contribution in the topics: Aerosol & Environmental science. The organization has 418 authors who have published 1252 publications receiving 32586 citations.

Internally mixed nanoparticles from oscillatory spark ablation between electrodes of different materials

Abstract: The increasing need for engineered alloy nanoparticles (NPs) in diverse fields has spurred efforts to explore efficient/green synthesis methods. In this respect, spark ablation provides a scalable ...

Conformations and Dynamics of Polymer Chains in Cis and Trans Polybutadiene/Silica Nanocomposites through Atomistic Simulations: From the Unentangled to the Entangled Regime

Abstract: The conformations and the dynamics of poly­(butadiene) (PB) chains, of various molecular weights, in PB/silica nanocomposites are studied through long-time atomistic molecular dynamics simulations at T = 413 K, well above Tg. The effect of the stereochemistry of PB chains is addressed by simulation of cis-1,4-PB/silica and trans-1,4-PB/silica nanocomposites. The model systems contain 30 wt % (≈12 vol %) silica nanoparticles (NPs) of diameter ≈4 nm. The nanocomposites are characterized through analyzing (i) interfacial packing and the dimensions of the PB chains; (ii) statistics of the train, bridge, loop, and tail conformations of adsorbed chains and the coupling between segmental orientational dynamics and chain conformations; and (iii) the orientational and translational dynamics of the polymer chains and the desorption kinetics of chains and segments. The dimensions of PB chains, excluding a small fraction of chains that wrap around the NP, are not affected. The segmental and terminal dynamics of PB chains are slower in the nanocomposites than in the respective bulk melts. Moreover, the dynamics of PB chains in the nanocomposites is very heterogeneous, and a coupling between the dynamics and the conformation of PB chains is observed: the adsorbed segments (trains) and the chains that have a higher number of contacts to the NPs are more decelerated. Additionally, at long times, bridge segments exhibit a very slow orientational decorrelation. The self-diffusion coefficients, D, of PB chains in the nanocomposites are also reduced compared to the respective bulk systems. A clear crossover from the unentangled (Rouse-like) to the entangled (reptation-like) regime is observed based on the calculation of the segmental mean-square displacement and D as a function of the chain length. The effective tube diameter of entangled PB chains in the nanocomposites is estimated to be slightly smaller than in the pure melts. The deceleration of dynamics in the nanocomposites, in both Rouse and reptation-like regimes, is discussed in terms of a higher effective monomeric friction coefficient. Finally, the correlation times for the desorption of segments and chains are much larger than the segmental and end-to-end-vector correlation times, respectively.

Quantum Roaming in the Complex-Forming Mechanism of the Reactions of OH with Formaldehyde and Methanol at Low Temperature and Zero Pressure: A Ring Polymer Molecular Dynamics Approach.

Abstract: The quantum dynamics of the title reactions are studied using the ring polymer molecular dynamics (RPMD) method from 20 to 1200 K using recently proposed full dimensional potential energy surfaces which include long-range dipole–dipole interactions. A V-shaped dependence of the reaction rate constants is found with a minimum at 200–300 K, in rather good agreement with the current experimental data. For temperatures above 300 K the reaction proceeds following a direct H-abstraction mechanism. However, below 100 K the reaction proceeds via organic-molecule···OH collision complexes, with very long lifetimes, longer than 10–7 s, associated with quantum roaming arising from the inclusion of quantum effects by the use of RPMD. The long lifetimes of these complexes are comparable to the time scale of the tunnelling to form reaction products. These complexes are formed at zero pressure because of quantum effects and not only at high pressure as suggested by transition state theory (TST) calculations for OH + meth...

Modeled Global Effects of Airborne Desert Dust on Air Quality and Premature Mortality

Abstract: Fine particulate matter is one of the most important factors contributing to air pollution. Epidemiological studies have related increased levels of atmospheric particulate matter to premature huma...

Formation and growth of atmospheric nanoparticles in the eastern Mediterranean: results from long-term measurements and process simulations

Abstract: . Atmospheric new particle formation (NPF) is a common phenomenon all over the world. In this study we present the longest time series of NPF records in the eastern Mediterranean region by analyzing 10 years of aerosol number size distribution data obtained with a mobility particle sizer. The measurements were performed at the Finokalia environmental research station on Crete, Greece, during the period June 2008–June 2018. We found that NPF took place on 27 % of the available days, undefined days were 23 % and non-event days 50 %. NPF is more frequent in April and May probably due to the terrestrial biogenic activity and is less frequent in August. Throughout the period under study, nucleation was observed also during the night. Nucleation mode particles had the highest concentration in winter and early spring, mainly because of the minimum sinks, and their average contribution to the total particle number concentration was 8 %. Nucleation mode particle concentrations were low outside periods of active NPF and growth, so there are hardly any other local sources of sub-25 nm particles. Additional atmospheric ion size distribution data simultaneously collected for more than 2 years were also analyzed. Classification of NPF events based on ion spectrometer measurements differed from the corresponding classification based on a mobility spectrometer, possibly indicating a different representation of local and regional NPF events between these two measurement data sets. We used the MALTE-Box model for simulating a case study of NPF in the eastern Mediterranean region. Monoterpenes contributing to NPF can explain a large fraction of the observed NPF events according to our model simulations. However the adjusted parameterization resulting from our sensitivity tests was significantly different from the initial one that had been determined for the boreal environment.