Download or read book Molecular Dynamics Study of the Kinetics of Heterogeneous Ice Nucleation written by Chu Li and published by . This book was released on 2018 with total page 101 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nucleation of Water written by Ari Laaksonen and published by Elsevier. This book was released on 2021-12-06 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nucleation of Water: From Fundamental Science to Atmospheric and Additional Applications provides a comprehensive accounting of the current state-of-the-art regarding the nucleation of water. It covers vapor-liquid, liquid-vapor, liquid-ice and vapor-ice transitions and describes basic kinetic and thermodynamic concepts in a manner understandable to researchers working on specific applications. The main focus of the book lies in atmospheric phenomena, but it also describes engineering and biological applications. Bubble nucleation, although not of major atmospheric relevance, is included for completeness. This book presents a single, go-to resource that will help readers understand the breadth and depth of nucleation, both in theory and in real-world examples. Offers a single, comprehensive work on water nucleation, including cutting- edge research on ice, cloud and bubble nucleation Written primarily for atmospheric scientists, but it also presents the theories in such a way that researchers in other disciplines will find it useful Written by one of the world's foremost experts on ice nucleation

Download or read book Furthering Our Understanding of Heterogeneous Ice Nucleation with Molecular Simulation written by and published by . This book was released on 2014 with total page 207 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Furthering Our Understanding of Heterogeneous Ice Nucleation with Molecular Simulation written by Stephen James Cox and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Investigating Ice Nucleation at Negative Pressures Using Molecular Dynamics written by and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract : Atmospheric scientists and climate modelers are faced with uncertainty around the process of ice production in clouds. While significant progress has been made in predicting homogeneous and heterogeneous ice nucleation rates as a function of temperature, recent experiments have shown that ice nucleation rates can be enhanced without decreasing temperature, through various mechanical agitations. One hypothesis for these findings is that mechanisms of stretching water and thereby inducing negative pressure in the liquid could lead to an increase in freezing rate. To better understand the viability of this concept, the effect of negative pressure on ice nucleation rates needs to be explored. To that end, we have conducted molecular dynamics simulations of water at negative pressures. Homogeneous ice nucleation rates for the ML-mW and mW water models are evaluated at pressures ranging from atmospheric to -1000 atm, using Forward Flux Sampling and constant cooling simulations. We find that the density difference between ice and liquid water is central in determining the increase in nucleation rate with negative pressure. With these results, we analyze an equation that has been posed as a first order approximation to quantify how nucleation rate changes with negative pressure. The equation predicts the slope of lines of constant nucleation rate in temperature--pressure coordinates, shining a light on the importance of the water density anomaly in determining the slope. We conclude that this linear approximation works well for the mW and ML-mW water models and can be useful in making experimental predictions to advance the study of ice nucleation mechanisms.

Download or read book Kinetics of Ice Nucleation from Water and Electrolyte Solutions written by George R. Wood and published by . This book was released on 1969 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Molecular Dynamics Investigation of Ice Nucleation Induced by Electric Fields written by Jingyi Yan and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Heterogeneous Ice Nucleation from Laboratory generated and Field collected Aerosol Particles written by Bingbing Wang and published by . This book was released on 2011 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Laboratory Studies of Deposition Mode Heterogeneous Ice Nucleation Effect of Ice Nuclei Composition Size and Surface Area written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: PhD.

Download or read book Heterogeneous Ice Nucleation written by Anatoli Bogdan and published by . This book was released on 1994 with total page 79 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Physics and Chemistry of Ice written by Werner Kuhs and published by Royal Society of Chemistry. This book was released on 2007-10-31 with total page 721 pages. Available in PDF, EPUB and Kindle. Book excerpt: Physics and Chemistry of Ice is an authoritative summary of state-of the-art research contributions from the world's leading scientists. A key selection of submissions from the 11th International Conference on the Physics and Chemistry of Ice, 2006 are presented here with a foreword by Werner F. Kuhs. An invaluable resource, this book provides researchers and professionals with up-to-date coverage on a wide range of areas in ice science including: * Spectroscopic and diffraction studies * Molecular dynamics simulations * Studies of Ice Mechanics * Quantum mechanical ab initio calculations * Ice and hydrate crystal growth and inhibition studies * Bulk and surface properties of ice and gas hydrates * Snow physics and chemistry This insight into topical aspects of ice research is a key point of reference for physicists, chemists, glaciologists, cryo-biologists and professionals working in the fields of ice and hydrogen bonding.

Download or read book A Water Activity Based Model of Heterogeneous Ice Nucleation Kinetics for Freezing of Water and Aqueous Solution Droplets written by and published by . This book was released on 2013 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: Immersion freezing of water and aqueous solutions by particles acting as ice nuclei (IN) is a common process of heterogeneous ice nucleation which occurs in many environments, especially in the atmosphere where it results in the glaciation of clouds. Here we experimentally show, using a variety of IN types suspended in various aqueous solutions, that immersion freezing temperatures and kinetics can be described solely by temperature, T, and solution water activity, aw, which is the ratio of the vapour pressure of the solution and the saturation water vapour pressure under the same conditions and, in equilibrium, equivalent to relative humidity (RH). This allows the freezing point and corresponding heterogeneous ice nucleation rate coefficient, Jhet, to be uniquely expressed by T and aw, a result we term the aw based immersion freezing model (ABIFM). This method is independent of the nature of the solute and accounts for several varying parameters, including cooling rate and IN surface area, while providing a holistic description of immersion freezing and allowing prediction of freezing temperatures, Jhet, frozen fractions, ice particle production rates and numbers. Our findings are based on experimental freezing data collected for various IN surface areas, A, and cooling rates, r, of droplets variously containing marine biogenic material, two soil humic acids, four mineral dusts, and one organic monolayer acting as IN. For all investigated IN types we demonstrate that droplet freezing temperatures increase as A increases. Similarly, droplet freezing temperatures increase as the cooling rate decreases. The log10(Jhet) values for the various IN types derived exclusively by T and aw, provide a complete description of the heterogeneous ice nucleation kinetics. Thus, the ABIFM can be applied over the entire range of T, RH, total particulate surface area, and cloud activation timescales typical of atmospheric conditions. Finally, we demonstrate that ABIFM can be used to derive frozen fractions of droplets and ice particle production for atmospheric models of cirrus and mixed phase cloud conditions.

Download or read book Experimental Investigation of Heterogeneous Nucleation of Ice in Remote Locations written by Alessia Nicosia and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Heterogeneous ice nucleation is one element inside the overall complexity of the Earth's atmosphere, however, it has a profound impact on our representation of cloud properties: this process affects the optical thickness and lifetime of mixed-phase clouds and cirrus clouds, and it is responsible for a significant proportion of precipitations formed globally. Heterogeneous ice nucleation is related to the presence of specific aerosol particles, named ice nuclei particles (INP), with the unique ability of lowering the energy barrier required for the formation of ice crystals, especially where cloud's temperatures are >-38 °C. In the last decades, significant advancements have been made to the fundamental understanding of ice nucleation, however the lack of knowledge on the cloud ice phase still contributes to major uncertainties in climate model prediction of radiative forcing. This is partly due to limited observational data quantifying INP distributions and properties all over the world, especially in remote locations. In the first part of this thesis, field observations of ice nucleating particles have been performed at the Italian Climate Observatory “O. Vittori” on Mountain Cimone (2165 m above sea level), in the spring 2014 and autumn 2015, within the Bacchus and Air Sea Lab projects. For the first time we report the results of offline INP measurements, performed at a high altitude site within the Mediterranean basin. In the period 19-29 May 2014, a parallel campaign took place at the low-altitude station San Pietro Capofiume, a rural site in the Po Valley. The two campaigns were concerned, for a few days, by a Saharan Dust transport Event, which was recorded simultaneously at the high and the low-level station. We investigated the ambient number concentration of INP under condensation freezing activation mechanism (at -18 °C and above water saturation). In the second part of this thesis, we present the observations that were performed during the Arctic campaign Parcs-Maca, in the period of transition among the polar night and the polar day. We could characterise for the first time the ice nucleating and physical/chemical properties of the Arctic Primary Marine Aerosol, in a laboratory-controlled generation approach, that was combined to a mesocosm experiment. The aim of the mesocosm experiment was to adopt a multidisciplinary approach to study the effect of marine pollution on marine emissions. We found a moderate but significant decrease of the ice nuclei concentration in the polluted seawater (with respect to the control seawater) recorded in the freezing range between -8.5 and -19 °C and activated through immersion-freezing. Within the seaspray our measurements have indicated a relation among INP active at warm temperature (above -15 °C through immersion-freezing) and a calcium enrichment detected in PM1 filters (and followed by an apparent Chloride depletion). On the basis of our observations, and the results reported from other studies, a few suggestions on the nature of these marine ice nuclei have been suggested. In summary, the measurements made for this thesis provide new information on the concentrations of ice nuclei in ambient aerosol particles in remote regions (a high-altitude observatory in the central Mediterranean region) and in relation to a specific source (the Arctic sea spray).

Download or read book Modelling Studies on the Impact of Heterogeneous Ice Nucleation on Mixed phase Clouds written by Ross James Herbert and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Study of Heterogeneous Ice Nucleation Mechanisms Using a New Ice Thermal Diffusion Chamber written by Robert Charles Schaller and published by . This book was released on 1975 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: This new method for precision control of thermodynamic environmental variables, supersaturation in particular, that surround freely suspended ice nuclei particles, and subsequent theoretical analysis of data, have resulted in some discoveries and clarified many long standing confusions concerning heterogeneous ice nucleation. The present study has been carried out with three main purposes: first, to build and operate a new ice thermal diffusion chamber which is capable of precisely controlling a range of supersaturations under steady-state conditions at a given temperature for an ice nucleant smoke (no substrate effect); second, to experimentally identify the mechanisms of ice nucleation under the defined environmental conditions of the experiment, and the aerosol particles; and, third, to develop a theory which could describe the obtained quantitative data.

Download or read book Chemical Characterization of Heterogeneous Ice Nuclei in the Atmosphere written by Sarah Sihvonen and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Aerosol particles impact the climate by serving as the seeds to form water droplets and ice to form clouds. However, these aerosol-cloud interactions are the least understood aspect of our understanding of the climate system. Mineral dust aerosol is the largest global source of ice nucleating particles. During atmospheric transport, mineral dust can be exposed to sulfuric acid, which has been shown to decrease the ice nucleation activity of these particles. Many explanations for this observation, such as chemical changes to the surface or product formation that blocks active sites, have been suggested. Our research focused on building a molecular picture of these surfaces to understand why sulfuric acid exposure reduces the ice nucleation activity of clay minerals such as kaolinite. We performed studies using X-ray diffraction and solid state NMR that investigate the changes that clay minerals undergo as a result of acid exposure. We are the first to show that the formation of a product on the surface of kaolinite was responsible for the decreased ice nucleation activity, not surface changes to the mineral itself. We continued to study aerosol-cloud interactions by using parcel models that explore the impact of ice growth surface kinetics on the competition between heterogeneous and homogeneous ice nucleation in clouds. We found that impaired growth of ice favors homogeneous freezing. The parcel models will be expanded to include our work on clay minerals to explore the impact of chemical aging of ice nuclei on overall cloud properties. We also studied the effect of acidic-processing on coal fly ash samples. Coal fly ash has been found to have a similar atmospheric impact as mineral dust, but is studied to a lesser extent. Like mineral dust, coal fly ash can serve as a source of bioavailable iron to phytoplankton in nutrient limited regions of the ocean. Fly ash has also been found to serve as an ice nucleating material. We performed aqueous sulfuric acid-treatment on fly ash samples representative of the types produced in the United States. We found that a soluble salt, gypsum (hydrated calcium sulfate), formed on three out of four samples. The most iron rich sample did not react with sulfuric acid. However, acidic-processing was shown to increase the amount of soluble iron which has implications for the biogeochemical cycle. These results also demonstrate that further work investigating these fly ash systems is warranted. In addition to our work on ice nucleation, we constructed a photoacoustic spectrometer to measure the absorbance of aerosol particles to study the optical properties of atmospheric aerosol. These measurements will aid in understanding the interactions of aerosol particles with light and the radiative balance of the planet.

Download or read book Surface Property Impacts on Heterogeneous Ice Nucleation of Engineered Materials written by Katherine Marak and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aerosol particles can facilitate heterogenous ice formation in the troposphere and stratosphere by acting as ice nuclei, modulating cloud formation/dissipation, precipitation, and their microphysical properties. Heterogeneous ice nucleation is driven by ice embryo formation on the particle surface, which can be influenced by features of the surface such as crystallinity, surface structure, lattice structure, defects, and functional groups. Probing for deeper understanding of what surface features have the greatest impact on heterogeneous freezing is significant and can be done with synthetic and modified materials. To characterize the effect of crystallinity, pores, and surface functional groups towards ice nucleation, samples of comparable silica systems, specifically, quartz, ordered and non-ordered porous amorphous silica samples with a range of pore sizes (2-11 nm), and non-porous functionalized silica spheres were used as models for mineral dust aerosol particles (Chapter 2). The results suggest that crystallinity has a larger effect than porosity on ice nucleation activity, as all of the porous silica samples investigated had lower onset freezing temperatures and lower ice nucleation activities than quartz. Our findings also suggest that pores alone are not sufficient to serve as effective active sites, and need some additional chemical or physical property, like crystallinity, to nucleate ice in immersion mode freezing. The addition of a low density of organic functional groups to non-porous samples showed little enhancement compared to the inherent nucleation activity of silica with native surface hydroxyl groups. The density of functional groups investigated in this work suggests that a different arrangement of surface groups may be needed for enhanced immersion mode ice nucleation activity. In summary, crystallinity dictates the ice nucleation activity of silica samples rather than porosity or low-density surface functional groups. Silver and gold nanoparticles with thiol ligands of different functionalities (alkane, carboxylic acid and alcohol) were investigated for immersion ice nucleation activities (Chapter 3). The alcohol ligand nanoparticles of both silver and gold had significantly higher activities than the alkane thiol ligand, with a 4.5 oC and 10.7 oC difference in median freezing temperature respectively. Silver nanoparticles capped with thiol alcohol ligands were also tested for aggregation and oxidative stability. The silver nanoparticles are oxidatively stable for at least 2 years. We have also shown that aggregates of nanoparticles have likely caused the activity for all of the silver and gold samples, as ice nucleation activity strongly diminished when large aggregates (>200 nm) were filtered from solution. Investigating the ice nucleation activity of synthetic ZSM-5 samples with varying Si:Al helps to clarify ice nucleation activity of natural mineral dust samples, which are often aluminosilicate based materials (Chapter 4). Additionally, ammonium is a very common cation in the atmosphere, and its effects on ice nucleation activity are still being studied. Ice nucleation temperature increases with increasing Al content. Additionally, when ammonium is the cation that is strongly adsorbed to the surface and in pores, initial freezing temperatures are reduced by up to 6 oC. Seeing a drastic decrease in ice nucleation activity in the presence of ammonium, suggests that the cation can interact with the surface to block active sites. In addition to ice nucleation, dust samples can affect human health. The goal of Chapter 5 is to present risk assessments for trace element concentrations in PM10 dusts from simulated road material and township roads with/without oil and gas produced water brine (O&GPWB) treatment. PM10 trace metal quantification was conducted by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and compared to values from EDS analysis on PM2.5. Among adults, PM10 inhalation lifetime cancer risks (CRinh range: 2.39E+01 to 7.73E+01) and hazard quotients for As, Ni and Pb exposure were elevated for O&GPWB, SFSR and RRA. Cumulative Pb dose for the O&GPWB-treated roads was 71 ng/kg by age 21, compared with 37 ng/kg for non-treated roads. Our results may be consistent with elevated blood lead (Pb) concentrations above state averages in this rural O&G producing region.