CIMS Sulfuric Acid Detection Efficiency Enhanced by Amines Due to Higher Dipole Moments: A Computational Study

2013 ◽  
Vol 117 (51) ◽  
pp. 14109-14119 ◽  
Author(s):  
Oona Kupiainen-Määttä ◽  
Tinja Olenius ◽  
Theo Kurtén ◽  
Hanna Vehkamäki
Keyword(s):  
Sulfuric Acid ◽  
Detection Efficiency ◽  
Computational Study ◽  
Dipole Moments

scholarly journals Enhancing effect of dimethylamine in sulfuric acid nucleation in the presence of water – a computational study

2010 ◽  
Vol 10 (10) ◽  
pp. 4961-4974 ◽  
Author(s):  
V. Loukonen ◽  
T. Kurtén ◽  
I. K. Ortega ◽  
H. Vehkamäki ◽  
A. A. H. Pádua ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Quantum Chemistry ◽  
Computational Study ◽  
Water Molecules ◽  
Enhancing Effect ◽  
Formation Energies

Abstract. We have studied the hydration of sulfuric acid – ammonia and sulfuric acid – dimethylamine clusters using quantum chemistry. We calculated the formation energies and thermodynamics for clusters of one ammonia or one dimethylamine molecule together with 1–2 sulfuric acid and 0–5 water molecules. The results indicate that dimethylamine enhances the addition of sulfuric acid to the clusters much more efficiently than ammonia when the number of water molecules in the cluster is either zero, or greater than two. Further hydrate distribution calculations reveal that practically all dimethylamine-containing two-acid clusters will remain unhydrated in tropospherically relevant circumstances, thus strongly suggesting that dimethylamine assists atmospheric sulfuric acid nucleation much more effectively than ammonia.

New Particle Formation Involving Charged Sulfuric Acid – Ammonia Clusters

2020 ◽  
Author(s):  
Vitus Besel ◽  
Jakub Kubečka ◽  
Theo Kurtén ◽  
Hanna Vehkamäki
Keyword(s):  
Sulfuric Acid ◽  
Computational Study ◽  
Cluster Formation ◽  
Chem Phys ◽  
Particle Formation ◽  
Empirical Method ◽  
Particle Nucleation ◽  
New Particle Formation ◽  
Charged Clusters ◽  
Ammonia Clusters

<div> <p>The bulk of aerosol particles in the atmosphere are formed by gas-to-particle nucleation (Merikanto et al., 2009). However, the exact process of single molecules forming cluster, which subsequently can grow into particles, remains largely unknown. Recently, sulfuric acid has been identified to play a key role in this new particle formation enhanced by other compounds such as organic acids (Zhang, 2010) or ammonia (Anttila et al., 2005). To identify the characteristics of cluster formation and nucleation involving sulfuric acid and ammonia in neutral, positive and negative modes, we conducted a computational study. We used a layered approach for configurational sampling of the molecular clusters starting from utilizing a genetic algorithm in order to explore the whole potential energy surface (PES) with all plausible geometrical minima, however, with very unreliable energies. The structures were further optimized with a semi-empirical method and, then, at the ωB97X-D DFT level of theory. After each step, the optimized geometries were filtered to obtain the global minimum configuration. Further, a high level of theory (DLPNO-CCSD(T)) was used for obtaining the electronic energies, in addition to performing DFT frequency analysis, to calculate the Gibbs free energies of formation. These were passed to the Atmospheric Cluster Dynamics Code (ACDC) (McGrath et al., 2012) for studying the evolution of cluster populations. We determined the global minima for the following sulfuric acid - ammonia clusters: (H<sub>2</sub>SO<sub>4</sub>)<sub>m</sub>(NH<sub>3</sub>)<sub>n</sub> with m=n, m=n+1 and n=m+1 for neutral clusters, (H<sub>2</sub>SO<sub>4</sub>)<sub>m</sub>(HSO<sub>4</sub>)<sup>−</sup>(NH<sub>3</sub>)<sub>n</sub> with m=n and n=m+1 for positively charged clusters, and (H<sub>2</sub>SO<sub>4</sub>)<sub>m</sub>(NH<sub>4</sub>)<sup>+</sup>(NH<sub>3</sub>)<sub>n</sub> with m=n and m=n+1 for negatively charged clusters. Further, we present the formation rates, steady state concentrations and fluxes of these clusters calculated using ACDC and discuss how a new configurational sampling procedure, more precise quantum chemistry methods and parameters, such as symmetry and a quasiharmonic approach, impact these ACDC results in comparison to previous studies.</p> </div><div> <p><em>References:<br></em><em>J. Merikanto, D. V. Spracklen, G. W. Mann, S. J. Pickering, and K. S. Carslaw (2009). Atmos. Chem.  Phys., 9, 8601-8616. <br>R. Zhang (2010). Science, 328, 1366-1367. <br>T. Anttila, H. Vehkamäki, I. Napari, M. Kulmala (2005). Boreal Env. Res., 10, 523. <br>M.J. McGrath, T. Olenius, I.K. Ortega, V. Loukonen, P.  Paasonen, T. Kurten, M. Kulmala (2012). Atmos. Chem. Phys., 12, 2355. <br></em></p> </div>

scholarly journals Homogenous nucleation of sulfuric acid and water at close to atmospherically relevant conditions

2011 ◽  
Vol 11 (11) ◽  
pp. 5277-5287 ◽  
Author(s):  
D. Brus ◽  
K. Neitola ◽  
A.-P. Hyvärinen ◽  
T. Petäjä ◽  
J. Vanhanen ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Gas Phase ◽  
Acid Concentration ◽  
High Efficiency ◽  
Detection Efficiency ◽  
Sulfuric Acid Concentration ◽  
Ionization Mass ◽  
Atmospheric Measurements ◽  
Flow Tube ◽  
Particle Counter

Abstract. In this study the homogeneous nucleation rates in the system of sulfuric acid and water were measured by using a flow tube technique. The goal was to directly compare particle formation rates obtained from atmospheric measurements with nucleation rates of freshly nucleated particles measured with particle size magnifier (PSM) which has detection efficiency of unity for particles having mobility diameter of 1.5 nm. The gas phase sulfuric acid concentration in this study was measured with the chemical ionization mass spectrometer (CIMS), commonly used in field measurements. The wall losses of sulfuric acid were estimated from measured concentration profiles along the flow tube. The initial concentrations of sulfuric acid estimated from loss measurements ranged from 108 to 3 × 109 molecules cm−3. The nucleation rates obtained in this study cover about three orders of magnitude from 10−1 to 102 cm−3 s−1 for commercial ultrafine condensation particle counter (UCPC) TSI model 3025A and from 101 to 104 cm−3 s−1 for PSM. The nucleation rates and the slopes (dlnJ/dln [H2SO4]) show satisfactory agreement when compared to empirical kinetic and activation models and the latest atmospheric nucleation data. To the best of our knowledge, this is the first experimental work providing temperature dependent nucleation rate measurements using a high efficiency particle counter with a cut-off-size of 1.5 nm together with direct measurements of gas phase sulfuric acid concentration.

The C-, Si-, Ge-Doped (6,3) Chiral BNNTs: A Computational Study

2015 ◽  
Vol 70 (10) ◽  
pp. 859-866 ◽  
Author(s):  
Mohammad Reza Zardoost ◽  
Behnam Dehbandi ◽  
Marjan Dehbandi
Keyword(s):  
Density Functional ◽  
Computational Study ◽  
Dipole Moments ◽  
Band Gaps ◽  
Chemical Shielding ◽  
Functional Theory ◽  
Bond Lengths ◽  
Nmr Parameters ◽  
Average Bond ◽  
Structure Properties

AbstractElectronic structure properties including bond lengths, bond angles, dipole moments (μ), energies, band gaps, nuclear magnetic resonance (NMR) parameters of the isotropic and anisotropic chemical shielding parameters for the sites of various atoms were calculated using density functional theory for C-, Si-, and Ge-doped (6,3) chiral BNNTs. The calculations indicated that average bond lengths were as follows: Ge–N>Si–N>C–N and Ge–B>Si–B>C–B. The dipole moments for C-, Si-, and Ge-doped (6,3) chiral BNNTs structures show fairly large changes with respect to the pristine model.

Computational Study of the Reaction between Biogenic Stabilized Criegee Intermediates and Sulfuric Acid

2007 ◽  
Vol 111 (17) ◽  
pp. 3394-3401 ◽  
Author(s):  
Theo Kurtén ◽  
Boris Bonn ◽  
Hanna Vehkamäki ◽  
Markku Kulmala
Keyword(s):  
Sulfuric Acid ◽  
Computational Study ◽  
Criegee Intermediates ◽  
Stabilized Criegee Intermediates

Hydrogen Bonding in the Sulfuric Acid–Methanol–Water System: A Matrix Isolation and Computational Study

2014 ◽  
Vol 119 (11) ◽  
pp. 2271-2280 ◽  
Author(s):  
Mark Rozenberg ◽  
Aharon Loewenschuss ◽  
Claus J. Nielsen
Keyword(s):  
Hydrogen Bonding ◽  
Sulfuric Acid ◽  
Computational Study ◽  
Matrix Isolation ◽  
Water System ◽  
System A

scholarly journals Effect of Hydration and Base Contaminants on Sulfuric Acid Diffusion Measurement: A Computational Study

2014 ◽  
Vol 48 (6) ◽  
pp. 593-603 ◽  
Author(s):  
Tinja Olenius ◽  
Theo Kurtén ◽  
Oona Kupiainen-Määttä ◽  
Henning Henschel ◽  
Ismael K. Ortega ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Computational Study ◽  
Diffusion Measurement ◽  
Acid Diffusion

scholarly journals Potential Exploration of Recent FDA-Approved Anticancer Drugs Against Models of SARS-CoV-2’s Main Protease and Spike Glycoprotein: A Computational Study

2020 ◽  
Vol 11 (3) ◽  
pp. 10059-10073
Keyword(s):  
Anticancer Drugs ◽  
Computational Study ◽  
Chemical Reactivity ◽  
Dipole Moments ◽  
Amino Acid Residues ◽  
Spike Glycoprotein ◽  
Binding Ability ◽  
Reactivity Descriptors ◽  
Main Protease ◽  
Chemical Reactivity Descriptors

COVID-19 has become a worldwide risk to the healthcare system of practically every nation of the world, which originated from Wuhan, China. To date, no specific drugs are available to treat this disease. The exact source of the SARS-CoV-2 is yet unknown, although the early cases are associated with the Seafood market in Huanan, South China. This manuscript reports the in silico molecular modeling of recent FDA-approved anticancer drugs (Capmatinib, Pemigatinib, Selpercatinib, and Tucatinib) for their inhibitory action against COVID-19 targets. The selected anticancer drugs are docked on SARS-CoV-2 main protease (PDB ID: 6LU7) and SARS-CoV-2 spike glycoprotein (PDB ID: 6M0J) to ascertain the binding ability of these drugs. ADMET parameters of the drugs are assessed, and in addition, DFT calculations are done to investigate the pharmacokinetics, thermal parameters, dipole moments, and chemical reactivity descriptors. The docking energies (ΔG) and the interacting amino acid residues are discussed. Promising molecular docking conclusions have been accomplished, which demonstrated the potential of selected anticancer drugs for plausible drug development to fight COVID-19. Further optimizations with the drug may support the much-needed rapid response to mitigate the pandemic.

COMPUTATIONAL STUDY OF A CNT-URACIL-CNT COMPOUND

2011 ◽  
Vol 25 (15) ◽  
pp. 1335-1341 ◽  
Author(s):  
MARYAM MIRZAEI ◽  
MOHAMMAD YOUSEFI ◽  
MAHMOUD MIRZAEI
Keyword(s):  
Carbon Nanotubes ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Computational Study ◽  
Dipole Moments ◽  
Coupling Constants ◽  
Modification Process ◽  
Quadrupole Coupling ◽  
Electronic Environments ◽  
Oxygen Atoms

Density functional calculations were performed to investigate the properties of a combination of two representative carbon nanotubes by assistance of the atomic sites of uracil, which is the characteristic nucleobase of RNA. The obtained parameters indicated that the resulting compound exhibit new properties with respect to the original nanotubes and uracil. The effects of the modification process were significant for the dipole moments and conductivity properties of the components as were seen by the significant changes in the new compound. The values of quadrupole coupling constants for the nitrogen and oxygen atoms of the uracil counterpart of the investigated models also indicated the effects of changes of the electronic environments of the components due to the modification process.

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