scholarly journals Atmospheric Spectroscopy and Photochemistry at Environmental Water Interfaces

2019 ◽  
Vol 70 (1) ◽  
pp. 45-69 ◽  
Author(s):  
J. Zhong ◽  
M. Kumar ◽  
J.M. Anglada ◽  
M.T.C. Martins-Costa ◽  
M.F. Ruiz-Lopez ◽  
...  
Keyword(s):  
Atmospheric Aerosols ◽  
Atmospheric Chemistry ◽  
Environmental Water ◽  
Bulk Solution ◽  
Water Interface ◽  
Atmospheric Species ◽  
Theoretical Investigations ◽  
Air Water Interface ◽  
Phase Chemistry ◽  
Interface Effects

The air–water interface is ubiquitous in nature, as manifested in the form of the surfaces of oceans, lakes, and atmospheric aerosols. The aerosol interface, in particular, can play a crucial role in atmospheric chemistry. The adsorption of atmospheric species onto and into aerosols modifies their concentrations and chemistries. Moreover, the aerosol phase allows otherwise unlikely solution-phase chemistry to occur in the atmosphere. The effect of the air–water interface on these processes is not entirely known. This review summarizes recent theoretical investigations of the interactions of atmosphere species with the air–water interface, including reactant adsorption, photochemistry, and the spectroscopy of reactants at the water surface, with an emphasis on understanding differences between interfacial chemistries and the chemistries in both bulk solution and the gas phase. The results discussed here enable an understanding of fundamental concepts that lead to potential air–water interface effects, providing a framework to understand the effects of water surfaces on our atmosphere.

scholarly journals Aerosol microdroplets exhibit a stable pH gradient

2018 ◽  
Vol 115 (28) ◽  
pp. 7272-7277 ◽  
Author(s):  
Haoran Wei ◽  
Eric P. Vejerano ◽  
Weinan Leng ◽  
Qishen Huang ◽  
Marjorie R. Willner ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Bulk Water ◽  
Bulk Solution ◽  
Spatial Gradient ◽  
Water Interface ◽  
Atmospheric Reactions ◽  
Air Water Interface ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering ◽  
2D And 3D

Suspended aqueous aerosol droplets (<50 µm) are microreactors for many important atmospheric reactions. In droplets and other aquatic environments, pH is arguably the key parameter dictating chemical and biological processes. The nature of the droplet air/water interface has the potential to significantly alter droplet pH relative to bulk water. Historically, it has been challenging to measure the pH of individual droplets because of their inaccessibility to conventional pH probes. In this study, we scanned droplets containing 4-mercaptobenzoic acid–functionalized gold nanoparticle pH nanoprobes by 2D and 3D laser confocal Raman microscopy. Using surface-enhanced Raman scattering, we acquired the pH distribution inside approximately 20-µm-diameter phosphate-buffered aerosol droplets and found that the pH in the core of a droplet is higher than that of bulk solution by up to 3.6 pH units. This finding suggests the accumulation of protons at the air/water interface and is consistent with recent thermodynamic model results. The existence of this pH shift was corroborated by the observation that a catalytic reaction that occurs only under basic conditions (i.e., dimerization of 4-aminothiophenol to produce dimercaptoazobenzene) occurs within the high pH core of a droplet, but not in bulk solution. Our nanoparticle probe enables pH quantification through the cross-section of an aerosol droplet, revealing a spatial gradient that has implications for acid-base–catalyzed atmospheric chemistry.

scholarly journals Simulation of Air–Water Interface Effects for High-speed Planing Hull

2020 ◽  
Vol 19 (3) ◽  
pp. 398-414
Author(s):  
Naga Venkata Rakesh Nimmagadda ◽  
Lokeswara Rao Polisetty ◽  
Anantha Subramanian Vaidyanatha Iyer
Keyword(s):  
High Speed ◽  
Water Interface ◽  
Fluid Forces ◽  
Transition Speed ◽  
High Speeds ◽  
Air Water Interface ◽  
Practical Design ◽  
Actual Flow ◽  
Wetted Surface Area ◽  
Interface Effects

Abstract High-speed planing crafts have successfully evolved through developments in the last several decades. Classical approaches such as inviscid potential flow–based methods and the empirically based Savitsky method provide general understanding for practical design. However, sometimes such analyses suffer inaccuracies since the air–water interface effects, especially in the transition phase, are not fully accounted for. Hence, understanding the behaviour at the transition speed is of fundamental importance for the designer. The fluid forces in planing hulls are dominated by phenomena such as flow separation at various discontinuities viz., knuckles, chines and transom, with resultant spray generation. In such cases, the application of potential theory at high speeds introduces limitations. This paper investigates the simulation of modelling of the pre-planing behaviour with a view to capturing the air–water interface effects, with validations through experiments to compare the drag, dynamic trim and wetted surface area. The paper also brings out the merits of gridding strategies to obtain reliable results especially with regard to spray generation due to the air–water interface effects. The verification and validation studies serve to authenticate the use of the multi-gridding strategies on the basis of comparisons with simulations using model tests. It emerges from the study that overset/chimera grids give better results compared with single unstructured hexahedral grids. Two overset methods are investigated to obtain reliable estimation of the dynamic trim and drag, and their ability to capture the spray resulting from the air–water interaction. The results demonstrate very close simulation of the actual flow kinematics at steady-speed conditions in terms of spray at the air–water interface, drag at the pre-planing and full planing range and dynamic trim angles.

Calcium phosphate growth beneath a polycationic monolayer at the air–water interface: effects of oscillating surface pressure on mineralization

Nanoscale ◽  
2010 ◽  
Vol 2 (11) ◽  
pp. 2440 ◽  
Author(s):  
Mathias Junginger ◽  
Katrin Bleek ◽  
Katarzyna Kita-Tokarczyk ◽  
Jürgen Reiche ◽  
Andriy Shkilnyy ◽  
...  
Keyword(s):  
Calcium Phosphate ◽  
Surface Pressure ◽  
Water Interface ◽  
Air Water Interface ◽  
Interface Effects

scholarly journals Air–water interface effects on the regioselectivity of singlet oxygenations of a trisubstituted alkene

2015 ◽  
Vol 56 (30) ◽  
pp. 4505-4508 ◽  
Author(s):  
Belaid Malek ◽  
Ashwini A. Ghogare ◽  
Rajib Choudhury ◽  
Alexander Greer
Keyword(s):  
Water Interface ◽  
Air Water Interface ◽  
Interface Effects

scholarly journals The Air-Water Interface Stabilises Alpha-Helical Conformations of the Insulin B-Chain

2019 ◽  
Author(s):  
David Cheung
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Bulk Solution ◽  
Water Interface ◽  
Helical Structures ◽  
Air Water Interface ◽  
Dynamics Simulations

Using enhanced molecular dynamics simulations the structure of the insulin B-chain was investigated at the air-water interface and in bulk solution. Significant differences in the conformational behaviour between these environments were found, with the air-water interface stabilising the formation of alpha-helical structures.

The Air-Water Interface Stabilises Alpha-Helical Conformations of the Insulin B-Chain

2019 ◽  
Author(s):  
David Cheung
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Bulk Solution ◽  
Water Interface ◽  
Helical Structures ◽  
Air Water Interface ◽  
Dynamics Simulations

Using enhanced molecular dynamics simulations the structure of the insulin B-chain was investigated at the air-water interface and in bulk solution. Significant differences in the conformational behaviour between these environments were found, with the air-water interface stabilising the formation of alpha-helical structures.

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