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Full-Text Articles in Physical Sciences and Mathematics

Brain Machine Interface Using Emotiv Epoc To Control Robai Cyton Robotic Arm, Daniel P. Prince, Mark J. Edmonds, Andrew J. Sutter, Matthew Thomas Cusumano, Wenjie Lu, Vijayan K. Asari Oct 2016

Brain Machine Interface Using Emotiv Epoc To Control Robai Cyton Robotic Arm, Daniel P. Prince, Mark J. Edmonds, Andrew J. Sutter, Matthew Thomas Cusumano, Wenjie Lu, Vijayan K. Asari

Vijayan K. Asari

The initial framework for an electroencephalography (EEG) thought recognition software suite is developed, built, and tested. This suite is designed to recognize human thoughts and pair them to actions for controlling a robotic arm. Raw EEG brain activity data is collected using an Emotiv EPOC headset. The EEG data is processed through linear discriminant analysis (LDA), where an intended action is identified. The EEG classification suite is being developed to increase the number of distinct actions that can be identified compared to the Emotiv recognition software. The EEG classifier was able to correctly distinguish between two separate physical movements. Future …


A Modular Approach For Key-Frame Selection In Wide Area Surveillance Video Analysis, Almabrok Essa, Paheding Sidike, Vijayan K. Asari Oct 2016

A Modular Approach For Key-Frame Selection In Wide Area Surveillance Video Analysis, Almabrok Essa, Paheding Sidike, Vijayan K. Asari

Vijayan K. Asari

This paper presents an efficient preprocessing algorithm for big data analysis. Our proposed key-frame selection method utilizes the statistical differences among subsequent frames to automatically select only the frames that contain the desired contextual information and discard the rest of the insignificant frames.

We anticipate that such key frame selection technique will have significant impact on wide area surveillance applications such as automatic object detection and recognition in aerial imagery. Three real-world datasets are used for evaluation and testing and the observed results are encouraging.


A Robust Fringe-Adjusted Joint Transform Correlator For Efficient Object Detection, Paheding Sidike, Vijayan K. Asari, Mohammad S. Alam Oct 2016

A Robust Fringe-Adjusted Joint Transform Correlator For Efficient Object Detection, Paheding Sidike, Vijayan K. Asari, Mohammad S. Alam

Vijayan K. Asari

The fringe-adjusted joint transform correlation (FJTC) technique has been widely used for real-time optical pattern recognition applications. However, the classical FJTC technique suffers from target distortions due to noise, scale, rotation and illumination variations of the targets in input scenes. Several improvements of the FJTC have been proposed in the literature to accommodate these problems. Some popular techniques such as synthetic discriminant function (SDF) based FJTC was designed to alleviate the problems of scale and rotation variations of the target, whereas wavelet based FJTC has been found to yield better performance for noisy targets in the input scenes. While these …


Pharmacological Validation Of An Inward-Rectifier Potassium (Kir) Channel As An Insecticide Target In The Yellow Fever Mosquito Aedes Aegypti, Matthew F. Rouhier, Rene Raphemot, Jerod S. Denton, Peter M. Piermarini Oct 2016

Pharmacological Validation Of An Inward-Rectifier Potassium (Kir) Channel As An Insecticide Target In The Yellow Fever Mosquito Aedes Aegypti, Matthew F. Rouhier, Rene Raphemot, Jerod S. Denton, Peter M. Piermarini

Matthew F Rouhier

Mosquitoes are important disease vectors that transmit a wide variety of pathogens to humans, including those that cause malaria and dengue fever. Insecticides have traditionally been deployed to control populations of disease-causing mosquitoes, but the emergence of insecticide resistance has severely limited the number of active compounds that are used against mosquitoes. Thus, to improve the control of resistant mosquitoes there is a need to identify new insecticide targets and active compounds for insecticide development. Recently we demonstrated that inward rectifier potassium (Kir) channels and small molecule inhibitors of Kir channels offer promising new molecular targets and active compounds, respectively, …


Discovery And Characterization Of A Potent And Selective Inhibitory Of Aedes Aegypti Inward Rectifier Potassium Channels, Matthew F. Rouhier, Rene Raphemot, Daniel R. Swale, Emily Days, C. David Weaver, Kimberly M. Lovell, Leah C. Konkel, Darren W. Engers, Sean F. Bollinger, Corey Hopkins, Peter M. Piermarini, Jerod S. Denton Oct 2016

Discovery And Characterization Of A Potent And Selective Inhibitory Of Aedes Aegypti Inward Rectifier Potassium Channels, Matthew F. Rouhier, Rene Raphemot, Daniel R. Swale, Emily Days, C. David Weaver, Kimberly M. Lovell, Leah C. Konkel, Darren W. Engers, Sean F. Bollinger, Corey Hopkins, Peter M. Piermarini, Jerod S. Denton

Matthew F Rouhier

Vector-borne diseases such as dengue fever and malaria, which are transmitted by infected female mosquitoes, affect nearly half of the world's population. The emergence of insecticide-resistant mosquito populations is reducing the effectiveness of conventional insecticides and threatening current vector control strategies, which has created an urgent need to identify new molecular targets against which novel classes of insecticides can be developed. We previously demonstrated that small molecule inhibitors of mammalian Kir channels represent promising chemicals for new mosquitocide development. In this study, high-throughput screening of approximately 30,000 chemically diverse small-molecules was employed to discover potent and selective inhibitors of Aedes …


Eliciting Renal Failure In Mosquitoes With A Small-Molecule Inhibitor Of Inward-Rectifying Potassium Channels, Matthew F. Rouhier, Rene Raphemot, Corey R. Hopkins, Rocco D. Gogliotti, Kimberly M. Lovel, Rebecca M. Hine, Dhairyasheel Ghosalkar, Anthony Longo, Klaus W. Beyenbach, Jerod S. Denton, Peter M. Piermarini Oct 2016

Eliciting Renal Failure In Mosquitoes With A Small-Molecule Inhibitor Of Inward-Rectifying Potassium Channels, Matthew F. Rouhier, Rene Raphemot, Corey R. Hopkins, Rocco D. Gogliotti, Kimberly M. Lovel, Rebecca M. Hine, Dhairyasheel Ghosalkar, Anthony Longo, Klaus W. Beyenbach, Jerod S. Denton, Peter M. Piermarini

Matthew F Rouhier

Mosquito-borne diseases such as malaria and dengue fever take a large toll on global health. The primary chemical agents used for controlling mosquitoes are insecticides that target the nervous system. However, the emergence of resistance in mosquito populations is reducing the efficacy of available insecticides. The development of new insecticides is therefore urgent. Here we show that VU573, a small-molecule inhibitor of mammalian inward-rectifying potassium (Kir) channels, inhibits a Kir channel cloned from the renal (Malpighian) tubules of Aedes aegypti (AeKir1). Injection of VU573 into the hemolymph of adult female mosquitoes (Ae. aegypti) disrupts the production and excretion of urine …


A Design Exploration On The Effectiveness Of Vocal Imitations, Stefano Delle Monache, Stefano Baldan, Davide A. Mauro Oct 2016

A Design Exploration On The Effectiveness Of Vocal Imitations, Stefano Delle Monache, Stefano Baldan, Davide A. Mauro

Davide Andrea Mauro

Among sonic interaction design practices a rising interest is given to the use of the voice as a tool for producing fast and rough sketches. Goal of the EU project SkAT-VG (Sketching Audio Technologies using Vocalization and Gestures, 2014-2016) is to develop vocal sketching as a reference practice for sound design by (i) improving our understanding on how sounds are communicated through vocalizations and gestures, (ii) looking for physical relations between vocal sounds and sound-producing phenomena, (iii) designing tools for converting vocalizations and gestures into parametrized sound models. We present the preliminary outcomes of a vocal sketching workshop held at …


Utilizing The Technology Acceptance Model To Assess The Employee Adoption Of Information Systems Security Measures, Cynthia M. Jones, Richard V. Mccarthy, Leila Halawi, Bahaudin Mujtaba Oct 2016

Utilizing The Technology Acceptance Model To Assess The Employee Adoption Of Information Systems Security Measures, Cynthia M. Jones, Richard V. Mccarthy, Leila Halawi, Bahaudin Mujtaba

Leila A. Halawi

In this study, the factors that affect employee acceptance of information systems security measures were examined by extending the Technology Acceptance Model. Partial least squares structural equation modeling was applied to examine these factors. 174 valid responses from employees from companies in various industry segments in the United States and Canada were analyzed. The results of the statistical analysis indicate that subjective norm moderated by management support showed the strongest effect on intention to use information systems security measures.


From Enrollment To Employment: A Dacum Approach To Information Systems And Information Security And Assurance Curriculum Design, Leila Halawi, Wendi M. Kappers, Aaron Glassman Oct 2016

From Enrollment To Employment: A Dacum Approach To Information Systems And Information Security And Assurance Curriculum Design, Leila Halawi, Wendi M. Kappers, Aaron Glassman

Leila A. Halawi

Issues associated with information security are numerous and diverse. Since the majority of organizational actions rely greatly on information and communication technologies, Information Systems (IS) security is now a main concern for firms, governments, institutes, and society as a whole. As a result, a plethora of graduate programs have been created, covering nearly every aspect of IS security. The authors review the current state of the IS industry presented in the literature, and identify a panel of IS experts in which to explore current job skill needs using a “Developing a Curriculum,” DACUM, process to support curriculum design for two …


Cyberspace: A Venue For Terrorism, David Bieda, Leila Halawi Oct 2016

Cyberspace: A Venue For Terrorism, David Bieda, Leila Halawi

Leila A. Halawi

This paper discusses how cyberspace has become a venue for terrorists groups for recruiting and proliferating propaganda and terrorism. Moreover, this study explores how the low cost Internet infrastructure and social media sites (such as Facebook, Twitter, and YouTube) have contributed to their networking and operations due to the convenience, in terms of availability, accessibility, message redundancy, ease of use, and the inability to censor content. Concepts such as cyber-weapons, cyber-attacks, cyber-war, and cyber-terrorism are presented and explored to assess how terrorist groups are exploiting cyberspace.


Using Survival Analysis To Identify Risk Factors For Treatment Interruption Among New And Retreatment Tuberculosis Patients In Kenya, Enos O. Masini, Omar Mansour, Clare E. Speer, Vittorio Addona, Christy L. Hanson, Joseph K. Sitienei, Hillary K. Kipruto, Martin Muhingo Githiomi, Brenda Nyambura Mungai Oct 2016

Using Survival Analysis To Identify Risk Factors For Treatment Interruption Among New And Retreatment Tuberculosis Patients In Kenya, Enos O. Masini, Omar Mansour, Clare E. Speer, Vittorio Addona, Christy L. Hanson, Joseph K. Sitienei, Hillary K. Kipruto, Martin Muhingo Githiomi, Brenda Nyambura Mungai

Vittorio Addona

" Despite high tuberculosis (TB) treatment success rate, treatment adherence is one of the major obstacles to tuberculosis control in Kenya. Our objective was to identify patient-related factors that were associated with time to TB treatment interruption and the geographic distribution of the risk of treatment interruption by county. Data of new and retreatment patients registered in TIBU, a Kenyan national case-based electronic data recording system, between 2013 and 2014 was obtained. Kaplan-Meier curves and log rank tests were used to assess the adherence patterns. Mixed-effects Cox proportional hazards modeling was used for multivariate analysis. Records from 90,170 patients were …


Peroxide Content Of Secondary Organic Aerosol, Ryan Caylor, Matthew Wise, John Shilling Oct 2016

Peroxide Content Of Secondary Organic Aerosol, Ryan Caylor, Matthew Wise, John Shilling

Matthew E. Wise

Secondary organic aerosol (SOA) formed from the oxidation of monoterpenes can impact the Earth’s radiation balance, act as cloud condensation nuclei and negatively affect human health. In the summer of 2015, the Secondary Organic Aerosol From Forest Emission Experiment (SOAFFEE) laboratory campaign was launched in order to study the physical properties of SOA generated from the oxidation of α−pinene and Δ-carene. Both compounds are gas-phase monoterpenes emitted into the atmosphere via biogenic sources. In this study, the peroxide content of SOA was determined using an iodometricspectrophotometric (IS) technique. It was found that the peroxide content of SOA generated during the …


Optical Properties Of Secondary Organic Aerosols, Felisha Imholt, Ryan Caylor, Matthew Wise, John Shilling Oct 2016

Optical Properties Of Secondary Organic Aerosols, Felisha Imholt, Ryan Caylor, Matthew Wise, John Shilling

Matthew E. Wise

It is well known that the increased warming effect due to greenhouse gases is a major environmental concern. While the amount of solar radiation absorbed by greenhouse gases is known to a high certainty, the amount absorbed by secondary organic aerosols (SOA) is not. The experimental procedure used to measure the amount of radiation absorbed by SOA was optimized using fulvic acid. The optimized method was then used to measure how much radiation SOA absorb between ~200 and 800 nm. Using this data, mass absorption coefficient (MAC) values at 405 nm and imaginary refractive indexes (k) were calculated. These values …


Composition And Optical Properties Of Secondary Organic Aerosol Particles, Felisha Imholt, Ryan Caylor, Matthew Wise, John Shilling Oct 2016

Composition And Optical Properties Of Secondary Organic Aerosol Particles, Felisha Imholt, Ryan Caylor, Matthew Wise, John Shilling

Matthew E. Wise

Research Questions: What is the chemical composition of SOA? Does SOA absorb UV/Vis radiation? If SOA does absorb UV/Vis radiation, how strong of an absorber is it?


Composition Of Secondary Organic Aerosols, Ryan Caylor, Felisha Imholt, Matthew Wise, John Shilling Oct 2016

Composition Of Secondary Organic Aerosols, Ryan Caylor, Felisha Imholt, Matthew Wise, John Shilling

Matthew E. Wise

The enhanced greenhouse effect is considered one our greatest global environmental problems. The amount of radiation absorbed by greenhouse gases is known to high certainty. However, absorbance from atmospheric aerosols particles is not. This study was conducted to determine the chemical composition of secondary organic aerosol particles (SOA) and to determine the compositional effect on their optical properties. The SOA were created in a temperature controlled chamber at Pacific Northwest National Laboratory (PNNL) in Richland, WA and collected on filters. The SOA were then analyzed for chemical composition using Fourier Transform Spectroscopy (FTIR). Analysis of the IR spectra revealed specific …


Laboratory Studies Of Ice Formation Pathways From Ammonium Sulfate Particles, M. E. Wise, K. J. Baustian, M. A. Tolbert Oct 2016

Laboratory Studies Of Ice Formation Pathways From Ammonium Sulfate Particles, M. E. Wise, K. J. Baustian, M. A. Tolbert

Matthew E. Wise

Cirrus clouds are composed of ice particles and their formation pathways have been studied extensively in the laboratory. The ability of ammonium sulfate particles to act as nuclei for cirrus clouds has been of particular importance because of their ubiquitous presence in the upper troposphere. The results of past laboratory experiments of homogeneous ice nucleation from ammonium sulfate particles show a wide range of freezing conditions. In the present study, a flow tube apparatus equipped with Fourier transform infrared spectroscopy was used to resolve these discrepancies. It was found that when ammonium sulfate particles were preconditioned at 100% relative humidity …


Laboratory Studies Of Ice Formation Pathways From Ammonium Sulfate Particles, M. E. Wise, K. J. Baustian, M. A. Tolbert Oct 2016

Laboratory Studies Of Ice Formation Pathways From Ammonium Sulfate Particles, M. E. Wise, K. J. Baustian, M. A. Tolbert

Matthew E. Wise

Cirrus clouds are composed of ice particles and their formation pathways have been studied extensively in the laboratory. The ability of ammonium sulfate particles to act as nuclei for cirrus clouds has been of particular importance because of their ubiquitous presence in the upper troposphere. The results of past laboratory experiments of homogeneous ice nucleation from ammonium sulfate particles show a wide range of freezing conditions. In the present study, a flow tube apparatus equipped with Fourier transform infrared spectroscopy was used to reexamine these discrepancies. It was found that when ammonium sulfate particles were preconditioned at 100% relative humidity …


Importance Of Aerosol Composition, Mixing State And Morphology For Heterogeneous Ice Nucleation: A Combined Field And Laboratory Approach, Kelly J. Baustian, Daniel J. Cziczo, Matthew E. Wise, Kerri A. Pratt, Gourihar Kulkarni, A. Gannet Hallar, Margaret A. Tolbert Oct 2016

Importance Of Aerosol Composition, Mixing State And Morphology For Heterogeneous Ice Nucleation: A Combined Field And Laboratory Approach, Kelly J. Baustian, Daniel J. Cziczo, Matthew E. Wise, Kerri A. Pratt, Gourihar Kulkarni, A. Gannet Hallar, Margaret A. Tolbert

Matthew E. Wise

In this study chemical compositions of background aerosol and ice nuclei were examined through laboratory investigations using Raman spectroscopy and field measurements by single-particle mass spectrometry. Aerosol sampling took place at Storm Peak Laboratory in Steamboat Springs, Colorado (elevation of 3210 m). A cascade impactor was used to collect coarse-mode aerosol particles for laboratory analysis by Raman spectroscopy; the composition, mixing state, and heterogeneous ice nucleation activity of individual particles were examined. For in situ analysis of fine-mode aerosol, ice nucleation on ambient particles was observed using a compact ice nucleation chamber. Ice crystals were separated from unactivated aerosol using …


Ice Nucleation In Internally Mixed Ammonium Sulfate/Dicarboxylic Acid Particles, Matthew E. Wise, Rebecca M. Garland, Margaret A. Tolbert Oct 2016

Ice Nucleation In Internally Mixed Ammonium Sulfate/Dicarboxylic Acid Particles, Matthew E. Wise, Rebecca M. Garland, Margaret A. Tolbert

Matthew E. Wise

Recent studies have shown that tropospheric sulfate aerosols commonly contain 50% or more by mass organic species. The influence of these organics on the chemical and physical properties of sulfate aerosols is not fully established. Using an aerosol flow tube technique, we have determined ice nucleation temperatures for particles composed of ammonium sulfate and mixtures of ammonium sulfate with a series of dicarboxylic acids. A calibration curve was developed to allow us to convert the freezing temperatures to a saturation ratio required for ice nucleation. At levels detectable by our experimental technique we find that the freezing temperatures and critical …


Impact Of Palmitic Acid Coating On The Water Uptake And Loss Of Ammonium Sulfate Particles, R. M. Garland, M. E. Wise, M. R. Beaver, H. L. Dewitt, A. C. Aiken, J. L. Jimenez, M. A. Tolbert Oct 2016

Impact Of Palmitic Acid Coating On The Water Uptake And Loss Of Ammonium Sulfate Particles, R. M. Garland, M. E. Wise, M. R. Beaver, H. L. Dewitt, A. C. Aiken, J. L. Jimenez, M. A. Tolbert

Matthew E. Wise

While water insoluble organics are prevalent in the atmosphere, it is not clear how the presence of such species alters the chemical and physical properties of atmospheric aerosols. Here we use a combination of FTIR spectroscopy, Transmission Electron Microscopy (TEM) and Aerosol Mass Spectrometry (AMS) to characterize ammonium sulfate particles coated with palmitic acid. Coated aerosols were generated by atomizing pure ammonium sulfate, mixing the particles with a heated flow of nitrogen with palmitic acid vapor, and then flowing the mixture through an in-line oven to create internally mixed particles. The mixing state of the particles was probed using the …


Solubility And Freezing Effects Of Fe2+ And Mg2+ In H2so4 Solutions Representative Of Upper Tropospheric And Lower Stratospheric Sulfate Particles, Matthew E. Wise, Sarah D. Brooks, Rebecca M. Garland, Daniel J. Cziczo, Scot T. Martin, Margaret A. Tolbert Oct 2016

Solubility And Freezing Effects Of Fe2+ And Mg2+ In H2so4 Solutions Representative Of Upper Tropospheric And Lower Stratospheric Sulfate Particles, Matthew E. Wise, Sarah D. Brooks, Rebecca M. Garland, Daniel J. Cziczo, Scot T. Martin, Margaret A. Tolbert

Matthew E. Wise

Chemical elements characteristic of earth minerals and meteorites are present within background tropospheric and stratospheric sulfate aerosol particles. However, it is unknown if these elements are present predominantly as solids, including possible sulfates, carbonates, and oxides, or rather as soluble aqueous metal ions or complexes. Further, it is unclear how these impurities could affect particle freezing. To address these questions, we have determined the total equilibrium metal solubility ([Fe2+]T and [Mg2+]T) in 20–90 wt % sulfuric acid solutions over the temperature range 200–300 K. We have measured solubilities using samples of MgSO4 …


Phase Changes In Internally Mixed Maleic Acid/Ammonium Sulfate Aerosols, Sarah D. Brooks, Rebecca M. Garland, Matthew E. Wise, Anthony J. Prenni, Melinda Cushing, Erika Hewitt, Margaret A. Tolbert Oct 2016

Phase Changes In Internally Mixed Maleic Acid/Ammonium Sulfate Aerosols, Sarah D. Brooks, Rebecca M. Garland, Matthew E. Wise, Anthony J. Prenni, Melinda Cushing, Erika Hewitt, Margaret A. Tolbert

Matthew E. Wise

A temperature controlled flow tube system equipped with Fourier transform infrared (FTIR) detection of particle phase and relative humidity was used to measure the deliquescence and efflorescence of ammonium sulfate, maleic acid, and internally mixed maleic acid/ammonium sulfate particles. Our results indicate that maleic acid aerosols begin to take up water starting at a low relative humidity, ∼20%, and continue the constant uptake of water until the final deliquescence relative humidity (DRH), 89%, is reached. Internally mixed particles containing maleic acid and ammonium sulfate were found to deliquesce at a lower relative humidity (RH) than either of the pure species. …


Hygroscopic Growth Of Ammonium Sulfate/Dicarboxylic Acids, Matthew E. Wise, Jason D. Surratt, Daniel B. Curtis, John E. Shilling, Margaret A. Tolbert Oct 2016

Hygroscopic Growth Of Ammonium Sulfate/Dicarboxylic Acids, Matthew E. Wise, Jason D. Surratt, Daniel B. Curtis, John E. Shilling, Margaret A. Tolbert

Matthew E. Wise

Recent studies have shown that tropospheric sulfate aerosols commonly contain 50% by mass organic species. The influence of these organics on the chemical and physical properties of sulfate aerosols is not fully established. We have measured the water activity of pure dicarboxylic acids and eutonic mixtures of ammonium sulfate/dicarboxylic acids at 25°C and have calculated van't Hoff factors for each individual system. We have also used the vapor pressure data to determine the hygroscopic growth curves for pure dicarboxylic acids and eutonic mixtures and provide power law fits to the data. For the systems studied we find that the presence …


Hygroscopic Behavior Of Nacl-Bearing Natural Aerosol Particles Using Environmental Transmission Electron Microscopy, Matthew E. Wise, Trudi A. Semeniuk, Roelof Bruintjes, Scot T. Martin, Lynn M. Russell, Peter R. Buseck Oct 2016

Hygroscopic Behavior Of Nacl-Bearing Natural Aerosol Particles Using Environmental Transmission Electron Microscopy, Matthew E. Wise, Trudi A. Semeniuk, Roelof Bruintjes, Scot T. Martin, Lynn M. Russell, Peter R. Buseck

Matthew E. Wise

We used conventional and environmental transmission electron microscopes to determine morphology, composition, and water uptake of individual natural inorganic aerosol particles collected from industrial pollution plumes and from clean and polluted marine environments. Five particle types are described in detail. They range from relatively insoluble mineral grains to internally mixed particles containing NaCl with other soluble or relatively insoluble material. We studied the hygroscopic behavior of these particles from 0 to 100% relative humidity (RH). Relatively insoluble materials do not take up water over the experimental RH range. Single crystals of NaCl from both natural and laboratory sources have a …


Ice Nucleation In Sulfuric Acid And Ammonium Sulfate Particles, Anthony J. Prenni, Matthew E. Wise, Sarah D. Brooks, Margaret A. Tolbert Oct 2016

Ice Nucleation In Sulfuric Acid And Ammonium Sulfate Particles, Anthony J. Prenni, Matthew E. Wise, Sarah D. Brooks, Margaret A. Tolbert

Matthew E. Wise

Cirrus clouds are composed of ice particles and are expected to form in the upper troposphere when highly dilute sulfate aerosols cool and become supersaturated with respect to ice. In the laboratory we have used Fourier transform infrared spectroscopy to monitor ice nucleation from sulfate particles for relevant compositions of sulfuric acid/water and ammonium sulfate/water aerosols. Measured freezing temperatures are presented as a function of aerosol composition, and results are compared to existing aerosol data. We find that sulfuric acid solution aerosol exhibits greater supercooling than ammonium sulfate solution aerosol of similar weight percent. Ice saturation ratios based on these …


State Transformations And Ice Nucleation In Amorphous (Semi-) Solid Organic Aerosol, K. J. Baustian, M. E. Wise, E. J. Jensen, G. P. Schill, M. A. Freedman, M. A. Tolbert Oct 2016

State Transformations And Ice Nucleation In Amorphous (Semi-) Solid Organic Aerosol, K. J. Baustian, M. E. Wise, E. J. Jensen, G. P. Schill, M. A. Freedman, M. A. Tolbert

Matthew E. Wise

Amorphous (semi-)solid organic aerosol particles have the potential to serve as surfaces for heterogeneous ice nucleation in cirrus clouds. Raman spectroscopy and optical microscopy have been used in conjunction with a cold stage to examine water uptake and ice nucleation on individual amorphous (semi-)solid particles at atmospherically relevant temperatures (200–273 K). Three organic compounds considered proxies for atmospheric secondary organic aerosol (SOA) were used in this investigation: sucrose, citric acid and glucose. Internally mixed particles consisting of each organic and ammonium sulfate were also investigated. Results from water uptake experiments followed the shape of a humidity-induced glass transition (Tg(RH)) curve …


State Transformations And Ice Nucleation In Glassy Or (Semi-) Solid Amorphous Organic Aerosol, K. J. Baustian, M. E. Wise, E. J. Jensen, G. P. Schill, M. A. Freedman, M. A. Tolbert Oct 2016

State Transformations And Ice Nucleation In Glassy Or (Semi-) Solid Amorphous Organic Aerosol, K. J. Baustian, M. E. Wise, E. J. Jensen, G. P. Schill, M. A. Freedman, M. A. Tolbert

Matthew E. Wise

Glassy or amorphous (semi-)solid organic aerosol particles have the potential to serve as surfaces for heterogeneous ice nucleation in cirrus clouds. Raman spectroscopy and optical microscopy have been used in conjunction with a cold stage to examine water uptake and ice nucleation on individual aqueous organic glass particles at atmospherically relevant temperatures (200–273 K). Three organic compounds considered proxies for atmospheric secondary organic aerosol (SOA) were used in this investigation: sucrose, citric acid and glucose. Internally mixed particles consisting of each organic species and ammonium sulfate were also investigated. Results from water uptake experiments were used to construct glass transition …


Determination Of The Optical Properties Of Secondary Organic Aerosol Particles, Matthew E. Wise, John Shilling, Felisha Imholt, Ryan Caylor Oct 2016

Determination Of The Optical Properties Of Secondary Organic Aerosol Particles, Matthew E. Wise, John Shilling, Felisha Imholt, Ryan Caylor

Matthew E. Wise

The enhanced greenhouse effect is currently considered to be our most important global environmental problem. While the magnitude of radiation absorbed by greenhouse gases is known to a high certainty, the absorption of radiation by atmospheric aerosol particles is not. In the initial Visiting Faculty Program application, we proposed the use of an ultraviolet-visible (UV/Vis) spectrometer equipped with a liquid waveguide capillary flow cell to determine the extent to which secondary organic aerosol particles (SOA) absorb visible light. Early in the research period, the UV/Vis technique was optimized for three solvent systems (methanol, water and 0.1 M hydrochloric acid). Using …


Depositional Ice Nucleation Onto Hydrated Nacl Particles: A New Mechanism For Ice Formation In The Troposphere, M. E. Wise, K. J. Baustian, T. Koop, M. A. Freedman, E. J. Jensen, M. A. Tolbert Oct 2016

Depositional Ice Nucleation Onto Hydrated Nacl Particles: A New Mechanism For Ice Formation In The Troposphere, M. E. Wise, K. J. Baustian, T. Koop, M. A. Freedman, E. J. Jensen, M. A. Tolbert

Matthew E. Wise

Sea-salt aerosol (SSA) particles are ubiquitous in the marine boundary layer and over coastal areas. Therefore SSA have ability to directly and indirectly affect the Earth's radiation balance. The influence SSA have on climate is related to their water uptake and ice nucleation characteristics. In this study, optical microscopy coupled with Raman spectroscopy was used to detect the formation of a crystalline NaCl hydrate that could form under atmospheric conditions. NaCl(s) particles (~1 to 10 μm in diameter) deliquesced at 75.7 ± 2.5% RH which agrees well with values previously established in the literature. NaCl(aq) particles effloresced to a mixture …


Determination Of Total Peroxide Content In Secondary Organic Aerosol Particles, Matthew E. Wise, John Shilling, Ryan Caylor Oct 2016

Determination Of Total Peroxide Content In Secondary Organic Aerosol Particles, Matthew E. Wise, John Shilling, Ryan Caylor

Matthew E. Wise

Secondary organic aerosol particles (SOA) formed from the oxidation of monoterpenes can impact the Earth’s radiation balance, act as cloud condensation nuclei and negatively affect human health. In the initial Visiting Faculty Program application, we proposed the use of an ultraviolet-visible spectrometer equipped with a liquid waveguide capillary flow cell to determine the extent to which SOA absorb visible light. The inclusion of Concordia University in the Secondary Organic Aerosol From Forest Emissions Experiment (SOAFFEE) laboratory campaign at PNNL necessitated a change in the proposed experiments. An iodometric-spectrophotometric (IS) technique was developed to quantify the total peroxide content in SOA. …