Author: Yuan You
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Emily Jean Ott
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Book Description
Aerosol particles can have a variety of compositions which determines their origin and their phase transitions. They can exist in the atmosphere where they are emitted from a variety of natural and anthropogenic sources. Aerosol particles can impact the climate directly though interacting with radiation or indirectly by nucleating cloud droplets and the clouds interacting with the sun. Aerosols can also impact health through the respiratory system. Additionally, aerosols can be used for synthetic purposes where they are created purposely for pharmaceutical or material creation along with many other applications. Understanding the factors that influence phase transitions that a particle may undergo is a prerequisite to understanding both atmospheric aerosol and synthetic aerosol. Several of these factors are investigated. First, the impact of the average ratio of oxygen to carbon (O:C) atoms in the organic molecules through the addition of sucrose to aerosol particles is studied using optical microscopy. A variety of organic molecules and salts combinations which are able to undergo phase separation were studied. The organic/inorganic mixtures exhibit a mixture both high and low separation relative humidities. Then sucrose was added until the particles no longer exhibit phase separation. Particles with higher separation relative humidities in the absence of sucrose required larger quantities of sucrose in order to inhibit phase separation. Additionally, phase separation was seen at higher O:C values than published previously, showing that while average O:C is a good indicator of phase separation, the precise composition of the particles is more important. The morphology of polymer/polymer aerosol particles according to their size was determined. In agreement with previous work, large particles undergo liquid-liquid phase separation while small particles remain homogeneous. Polyethylene glycol with dextran was used as well as polystyrene sulfonate with polyvinyl alcohol. Both of these systems inhibited phase separation at small sizes. To understand the size dependent morphology of polymer/polymer systems, different molecular weight mixtures of the polymers were studied. As the molecular weight of the polymers increased, smaller and smaller aerosol particles were able to undergo phase separation. This was further confirmed with a simple model based on the equations of phase separation and Flory-Huggins theory of a binary system which also showed the decrease in the size of the smallest phase separated particle as the molecular weight of the polymers increase in the size regime studied. The project created novel polymer materials and investigated the phase separation of polymer/polymer systems in confinement. The phase separation of submicron aerosol particles with different salts was investigated to determine the influence of different anions on the size dependent morphology of aerosol particles. The ammonium, sodium, chloride and sulfate ions were used. TEM was used to determine that sodium salts transition to homogenous particles at smaller sizes than their comparable ammonium salt. This difference is likely due to the softness of the ammonium ion when compared to the hardness of the sodium ion. This study provides insights into the size dependent morphology of sea spray aerosol may differ from that of continental aerosol in addition to increasing our understanding of how cations and anions impact phase transitions under confinement. These studies combined increase knowledge of confined phase transitions. While the O:C ratio has been studied before, the importance of the actual composition over the average O:C ratio has now been shown which is useful in understanding atmospheric aerosol particles. The presence of a size dependent morphology for polymer-polymer systems has been shown and modeled in addition to the development of novel polymeric materials. The phase separation differences between ammonium containing aerosols and sodium containing aerosols provides key insights into the differences between continental aerosol and sea spray aerosol in addition to contributing new information about the importance of cations in liquid-liquid phase separation of confined systems. Through these studies both atmospheric aerosol and synthetic aerosol are now better understood.

Author: Viorela-Gabriela Ciobanu
Publisher:
ISBN:
Category :
Languages : en
Pages : 164

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Author: Swarup China
Publisher: MDPI
ISBN: 3038971332
Category : Science
Languages : en
Pages : 215

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Book Description
This book is a printed edition of the Special Issue "Morphology and Internal Mixing of Atmospheric Particles" that was published in Atmosphere

Author: David L. Topping
Publisher: John Wiley & Sons
ISBN: 1119625653
Category : Science
Languages : en
Pages : 372

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Book Description
INTRODUCTION TO AEROSOL MODELLING Introduction to Aerosol Modelling: From Theory to Code An aerosol particle is defined as a solid or liquid particle suspended in a carrier gas. Whilst we often treat scientific challenges in a siloed way, aerosol particles are of interest across many disciplines. For example, atmospheric aerosol particles are key determinants of air quality and climate change. Knowledge of aerosol physics and generation mechanisms is key to efficient fuel delivery and drug delivery to the lungs. Likewise, various manufacturing processes require optimal generation, delivery and removal of aerosol particles in a range of conditions. There is a natural tendency for the aerosol scientist to therefore work at the interface of the traditional academic subjects of physics, chemistry, biology, mathematics and computing. The impacts that aerosol particles have are linked to their evolving chemical and physical characteristics. Likewise, the chemical and physical characteristic of aerosol particles reflect their sources and subsequent processes they have been subject to. Computational models are not only essential for constructing evidence-based understanding of important aerosol processes, but also to predict change and impact. Whilst existing textbooks provide an overview of theoretical frameworks on which aerosol models are based, there is a significant gap in reference material that provide training in translating theory into code. The purpose of this book is to provide readers with exactly that. In following the content provided in this book, you will be able to reproduce models of key processes that can either be used in isolation or brought together to construct a demonstrator 0D box-model of a coupled gaseous-particulate system. You may be reading this book as an undergraduate, postgraduate, seasoned researcher in the private/public sector or as someone who wishes to better understand the pathways to aerosol model development. Wherever you position yourself, it is hoped that the tools you will learn through this book will provide you with the basis to develop your own platforms and to ensure the next generation of aerosol modellers are equipped with foundational skills to address future challenges in aerosol science.

Author: Mehrnoush Mousavi-Fard
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Jingbiao Chen
Publisher: Frontiers Media SA
ISBN: 2832502296
Category : Science
Languages : en
Pages : 161

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Book Description
Ever since the invention of the cesium atomic clock in 1955, quantum frequency standards have seen considerable development over the decades, as a representative of quantum precision measurement. The progress in frequency measurements achieved in the past allowed one to perform quantum precision measurements of other physical and technical quantities with unprecedented precision, whenever they could be traced back to a frequency measurement. Using atomic transitions as frequency reference, quantum frequency standards are far less susceptible to external perturbations, and the identity of microscopic particles allows easy replication of a quantum standard with the same frequency. With laser cooling and trapping, cold atomic ensembles eliminate Doppler shift broadening, and have become the go-to quantum reference when precision and new physics are pursued. The advancement of laser cooling and cold atom physics, in addition to novel physical matter states such as Bose-Einstein Condensation, give rise to new experimental techniques in quantum precision measurement, especially quantum frequency standards, such as cesium fountain clocks dictating the SI second, as well as optical lattice clocks and single-ion optical clocks pushing the frontier of quantum metrology. Other areas of quantum metrology, such as gravitometers and magnetometers, also benefit greatly from cold atoms. For practical applications, quantum frequency standards are usually required to be compact and portable, and thermal atoms in the form of atomic beams or vapor cells are utilized. Commercially available quantum frequency standards such as cesium beam clocks or rubidium clocks have become the cornerstone of navigation and timekeeping. Compact optical clocks based on various laser spectroscopic techniques have also been developed. As researchers strive to break through the limits of accurate quantum measurement and atomic temperature, new fields such as precise measurement, quantum computing and quantum simulation based on cold atoms are further opened up, and challenges still exist to explore new physical phenomena in the field of cold atoms. In honor of Prof. Yiqiu Wang on the occasion of his 90th birthday, the main goal of this Research Topic is to provide a platform to exhibit the recent achievements and reveal the future challenges in quantum precision measurement, as well as studies of cold atom physics with quantum metrology, closely related to the long-term scientific research areas of Prof. Yiqiu Wang. Both Original Research and Review articles are encouraged. Topics of interest to this collection include, but are not limited to: • Quantum precision measurements • Microwave atomic clocks and their applications • Optical frequency standards, laser spectroscopy, and their applications • Quantum measurement based on cold atom • Quantum computation and quantum simulation based on cold atom

Author:
Publisher: Walter de Gruyter GmbH & Co KG
ISBN: 1501519379
Category : Science
Languages : en
Pages : 215

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Book Description
Atmospheric aerosols are an important and a highly complex component of the Earth’s atmosphere that alter the radiative forcing and the chemical composition of the gas phase. These effects have impacts on local air quality and the global climate. Atmospheric Aerosol Chemistry outlines research findings to date in aerosol chemistry and advances in analytical tools used in laboratory studies for studying their surface and bulk reactivity.

Author: National Academies of Sciences, Engineering, and Medicine
Publisher: National Academies Press
ISBN: 030944568X
Category : Science
Languages : en
Pages : 227

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Book Description
Our world is changing at an accelerating rate. The global human population has grown from 6.1 billion to 7.1 billion in the last 15 years and is projected to reach 11.2 billion by the end of the century. The distribution of humans across the globe has also shifted, with more than 50 percent of the global population now living in urban areas, compared to 29 percent in 1950. Along with these trends, increasing energy demands, expanding industrial activities, and intensification of agricultural activities worldwide have in turn led to changes in emissions that have altered the composition of the atmosphere. These changes have led to major challenges for society, including deleterious impacts on climate, human and ecosystem health. Climate change is one of the greatest environmental challenges facing society today. Air pollution is a major threat to human health, as one out of eight deaths globally is caused by air pollution. And, future food production and global food security are vulnerable to both global change and air pollution. Atmospheric chemistry research is a key part of understanding and responding to these challenges. The Future of Atmospheric Chemistry Research: Remembering Yesterday, Understanding Today, Anticipating Tomorrow summarizes the rationale and need for supporting a comprehensive U.S. research program in atmospheric chemistry; comments on the broad trends in laboratory, field, satellite, and modeling studies of atmospheric chemistry; determines the priority areas of research for advancing the basic science of atmospheric chemistry; and identifies the highest priority needs for improvements in the research infrastructure to address those priority research topics. This report describes the scientific advances over the past decade in six core areas of atmospheric chemistry: emissions, chemical transformation, oxidants, atmospheric dynamics and circulation, aerosol particles and clouds, and biogeochemical cycles and deposition. This material was developed for the NSF's Atmospheric Chemistry Program; however, the findings will be of interest to other agencies and programs that support atmospheric chemistry research.

Author: John Paul Frampton
Publisher: Frontiers Media SA
ISBN: 288963356X
Category :
Languages : en
Pages : 117

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Book Description
The phase separation of incompatible liquids has been a topic of significant importance in chemical and industrial engineering for many years. Well-understood examples of this phenomenon include the phase separation of oil with water and the phase separation of non-polar organic solvents with water. Similar behavior is observed when aqueous solutions of two or more incompatible polymers or polymers and salts are mixed. In these mixtures (referred to as aqueous two-phase systems), the separated phases are composed mostly of water. Aqueous two-phase systems have been used extensively for the extraction of high-value biological products from mixtures of biological materials. In recent years, aqueous two-phase systems have also found increased use as materials for streamlining and improving the capabilities of cell and molecular assays, and for the design of advanced cell culture systems. Similar behavior of biological materials in living systems has also been observed, with emerging roles in cell physiology.