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Articles 691 - 720 of 1318

Full-Text Articles in Environmental Health

Macromolecular-Clustered Facial Amphiphilic Antimicrobials, Md Anisur Rahman, Marpe Bam, Edgar Luat, Moumita Sharmin Jui, Mitra S. Ganewatta, Tinom Shokfai, Mitzi Nagarkatti, Alan W. Decho Dec 2018

Macromolecular-Clustered Facial Amphiphilic Antimicrobials, Md Anisur Rahman, Marpe Bam, Edgar Luat, Moumita Sharmin Jui, Mitra S. Ganewatta, Tinom Shokfai, Mitzi Nagarkatti, Alan W. Decho

Faculty Publications

Bacterial infections and antibiotic resistance, particularly by Gram-negative pathogens, have become a global healthcare crisis. We report the design of a class of cationic antimicrobial polymers that cluster local facial amphiphilicity from repeating units to enhance interactions with bacterial membranes without requiring a globally conformational arrangement associated with highly unfavorable entropic loss. This concept of macromolecular architectures is demonstrated with a series of multicyclic natural product-based cationic polymers. We have shown that cholic acid derivatives with three charged head groups are more potent and selective than lithocholic and deoxycholic counterparts, particularly against Gram-negative bacteria. This is ascribed to the formation …


Assessing Biofiltration Without Ozonation For Removal Of Trihalomethane Precursors In Drinking Water At The Beaver Water District Drinking Water Treatment Plant, Sana Ajaz Dec 2018

Assessing Biofiltration Without Ozonation For Removal Of Trihalomethane Precursors In Drinking Water At The Beaver Water District Drinking Water Treatment Plant, Sana Ajaz

Graduate Theses and Dissertations

Biofiltration without pre-ozonation has the capability to remove natural organic matter (NOM) fractions that serve as precursors of disinfection byproducts (DBPs), which include the four regulated trihalomethanes (THMs) and dichloroacetonitrile (DCAN). Rapid small-scale column tests (RSSCTs) and Pilot Plant filters operated at empty-bed contact times (EBCTs) of 4, 8, and 16 minutes were used to evaluate the performance of nutrient-amended (free ammonia and phosphorus) biofiltration for THM and DCAN precursor removal, as measured using formation potential (FP) tests. NOM surrogates – which include dissolved organic carbon (DOC), specific ultraviolet absorbance (SUVA254) and fluorescence-PARAFAC components – were measured weekly throughout the …


Watersheds In Planetary Health Research And Action, Aaron Jenkins, Anthony Capon, Joel Negin, Ben Marais, Tania Sorrell, Margot Parkes, Pierre Horwitz Dec 2018

Watersheds In Planetary Health Research And Action, Aaron Jenkins, Anthony Capon, Joel Negin, Ben Marais, Tania Sorrell, Margot Parkes, Pierre Horwitz

Research outputs 2014 to 2021

Watersheds (also known as water catchments and river basins) are recognised in contemporary science as important natural systems in which to investigate the complex socioecological foundations of health. A watershed is the spatially bound geophysical unit within which surface and shallow groundwater drain to a single collecting stream or river (see appendix). Watersheds are physical and abstract systems: they are open and hydrologically permeable, yet can be represented as functionally distinct. Collectively, watersheds comprise a complex hierarchical network, and thus exemplify the upstream and downstream nature of ecosystems. Watersheds include the social actors, relationships, and institutions located within their boundaries. …


Consumption Profiles Of Illicit And Neuropsychiatric Drugs In Urban And Rural Communities In Kentucky Using Sewage Epidemiology, Tara Croft, Katelyn Foppe, Rhiannon Huffines, Bikram Subedi Nov 2018

Consumption Profiles Of Illicit And Neuropsychiatric Drugs In Urban And Rural Communities In Kentucky Using Sewage Epidemiology, Tara Croft, Katelyn Foppe, Rhiannon Huffines, Bikram Subedi

Posters-at-the-Capitol

The drug overdose deaths in the USA increased by ~20% from 2015 to 2016 to the total >63,600 drug overdose deaths in 2016. Kentucky is among the highest rate of drug overdose death states in the USA. The current estimates of the prevalence of substance abuse are based on the self-reported surveys, overdose/toxicological reports, and drug-related crime statistics. Survey-based conventional approaches are not only cost and time-intensive but also underestimate the actual consumption of drugs. As “wastewater never lie,” the drug residues in raw wastewater collected from the centralized wastewater treatment plants were utilized to determine the consumption rate of …


Assesing Port Reception Facilities For Ship Generated Solid Waste : The Case Of The Port Of Walvis Bay, Namibia., Shapua Randy Mandela Kalomo Nov 2018

Assesing Port Reception Facilities For Ship Generated Solid Waste : The Case Of The Port Of Walvis Bay, Namibia., Shapua Randy Mandela Kalomo

World Maritime University Dissertations

No abstract provided.


Resilience Of The Nigerian Coastal Socio-Ecological System : Case Study Of The Niger Delta Region, Chinenye Joy Ijiomah Nov 2018

Resilience Of The Nigerian Coastal Socio-Ecological System : Case Study Of The Niger Delta Region, Chinenye Joy Ijiomah

World Maritime University Dissertations

No abstract provided.


A Qualitative Assessment Of Disability Friendly Water And Sanitation Facilities In Primary Schools, Rumphi, Malawi., Harlod Zaunda, Rochelle H. Holm, Ambumulire Itimu-Phiri, Mphatso Malota, Sian White Nov 2018

A Qualitative Assessment Of Disability Friendly Water And Sanitation Facilities In Primary Schools, Rumphi, Malawi., Harlod Zaunda, Rochelle H. Holm, Ambumulire Itimu-Phiri, Mphatso Malota, Sian White

Faculty and Staff Scholarship

Students with disabilities commonly face barriers when accessing water and using sanitation and hygiene facilities at school. International frameworks have prompted governments to enact local policies that enshrine these rights, guarantee equitable access to education and mandate inclusive infrastructure. This research was designed to explore whether Malawi has translated good policies into practice. Data were gathered in Rumphi district, Malawi, through structured field observations in ten schools and interviews with students with a disability (n = 23), teachers (n = 11) and government stakeholders (n = 2). No school had facilities that fully meet the needs of students with disabilities, …


Addressing Environmental Gentrification: Improving Environmental Health For Children And Youth Without Displacement, Tania Schusler, Amy Krings Nov 2018

Addressing Environmental Gentrification: Improving Environmental Health For Children And Youth Without Displacement, Tania Schusler, Amy Krings

Social Work: School of Social Work Faculty Publications and Other Works

Historically, low income communities and communities of color have borne the brunt of environmental pollution with limited access to environmental amenities. This has arisen, in part, due to marginalized communities’ lack of access and influence in environmental decision making, as well as legacies of racial and ethnic housing segregation (Cole & Foster, 2001). Environmental justice concerns include the disproportionate placement and inequitable regulation of polluting facilities in areas populated by people who are poor and/or racial minorities (Bryant, 1995: Bullard, 1993; Mohai & Bryant, 1992; Lavelle & Coyle, 1992). The inequitable distribution of environmental pollution is especially problematic for children’s …


Rationale, Design And Methods Of "Set The Rules": A Tailored Peer-To-Peer Health Information Intervention, Jennifer R. Warren, Brandi M. White Oct 2018

Rationale, Design And Methods Of "Set The Rules": A Tailored Peer-To-Peer Health Information Intervention, Jennifer R. Warren, Brandi M. White

Health and Clinical Sciences Faculty Publications

Ensuring equitable access to health information is one strategy to promote health equity for underserved communities, especially for low-income African Americans (AAs). Childcare centers are one viable site to deliver health information to address this disparity. This paper describes the methods used in a community-based participatory research project with a childcare facility that aimed to reduce environmental tobacco smoke (ETS) exposure among low-income AA children. Through collaboration and multiple data collection methods, partners identified communication strategies to overcome informational barriers. These initial findings indicated a peer-to-peer health information intervention, entitled “Set the Rules”, as the best strategy to increase awareness. …


La Asociación Entre La Contaminación Del Agua Y La Salud En Los Niños Menores De Cinco Años En Villa Garrote, Partido De Tigre / The Association Between Water Pollution And Health In Children Under Five In Villa Garrote, Tigre Party, Morgan Whyte Oct 2018

La Asociación Entre La Contaminación Del Agua Y La Salud En Los Niños Menores De Cinco Años En Villa Garrote, Partido De Tigre / The Association Between Water Pollution And Health In Children Under Five In Villa Garrote, Tigre Party, Morgan Whyte

Independent Study Project (ISP) Collection

La intersección entre el medio ambiente y la salud es un tema central en el estudio de la salud pública porque el acceso a un medio ambiente seguro es esencial para los resultados positivos en la salud. Este tema es particularmente relevante al considerar a Villa Garrote, una pequeña villa situada en el río Reconquista en el municipio de Tigre. Para abordar este tema dentro de esta villa, esta investigación pretende explorar la asociación entre la contaminación del agua y la salud de los niños. Además, los objetivos específicos de este estudio incluyen: investigar los principales elementos que contaminan el …


Hexahydro-1,3,5-Trinitro-1,3,5-Triazine (Rdx) Reduction By Granular Zero-Valent Iron In Continuous Flow Reactor, Amalia Terracciano, Jie Ge, Agamemnon Koutsospyros, Xiaoguang Meng, Benjamin Smolinski, Per Arienti Oct 2018

Hexahydro-1,3,5-Trinitro-1,3,5-Triazine (Rdx) Reduction By Granular Zero-Valent Iron In Continuous Flow Reactor, Amalia Terracciano, Jie Ge, Agamemnon Koutsospyros, Xiaoguang Meng, Benjamin Smolinski, Per Arienti

Civil Engineering Faculty Publications

Wastewater streams containing hexahydro-1, 3, 5-trinitro-1, 3, 5-triazine (RDX) are subject to regulatory discharge regulations that require processing through industrial waste treatment. Thus, the development of easy-to-apply technologies for the treatment of RDX-laden wastewater streams is imperative. In the present study, the reduction of RDX by granular zero valent iron (GZVI) in batch and column experiments was investigated. Preliminary batch tests conducted under both oxic and anoxic conditions showed that after 3.0 hours of reaction with GZVI, RDX was mainly converted to formaldehyde (CH2O), nitrate (NO3 - ), and ammonium (NH4 + ). Column filtration tests …


Abundance, Density, And Influencing Indicators Of Solid Waste Accumulation And Mitigation Solutions Along Coastlines On Isla Colón In Bocas Del Toro Province, Panamá, Andy Rhodes Oct 2018

Abundance, Density, And Influencing Indicators Of Solid Waste Accumulation And Mitigation Solutions Along Coastlines On Isla Colón In Bocas Del Toro Province, Panamá, Andy Rhodes

Independent Study Project (ISP) Collection

Solid waste accumulation is a significant issue in Latin America where poor infrastructure and management systems are present and with the exponential tourism growth in this region, the abundance of solid waste is also growing. This increase affects environmental, economic, and social factors such as pollution, a decline in tourism, and an increase in negative health effects. This study on Isla Colón, in the Province of Bocas del Toro, in western Panamá sought results on the abundance of solid waste along roadsides and beaches in the most populous and touristic locations. Approximately 2,160 meters squared were studied in Playa Bluff, …


Macro Implications Of Microplastics: A Comparative Study Of Microplastic Distribution In Bahía Almirante, Bocas Del Toro, Panama, Bonnie Feldberg Oct 2018

Macro Implications Of Microplastics: A Comparative Study Of Microplastic Distribution In Bahía Almirante, Bocas Del Toro, Panama, Bonnie Feldberg

Independent Study Project (ISP) Collection

Plastic is one of the most demanded materials in the modern world as it is durable and long lasting. However, that which makes it so commercially appealing also makes it environmentally degrading. Anthropogenic waste and specifically microplastics have been identified in natural habitats globally, with particular interest placed on marine ecosystems. This research aims to add to this pool by comparing microplastic concentrations in beach, mangrove, and shallow ocean sediment in Bahía Almirante, Bocas del Toro, Panama. Sediment samples were collected from each habitat type, processed, and then analyzed to obtain the number of microplastic particles per gram of dry …


Perceptions And Physical Realities Of Flood Risk In Cerro Punta, Chiriquí, Panamá, Julia Stanganelli Oct 2018

Perceptions And Physical Realities Of Flood Risk In Cerro Punta, Chiriquí, Panamá, Julia Stanganelli

Independent Study Project (ISP) Collection

Flooding is an issue of increasing global importance. With climate change and land-use alteration affecting hydrological cycles globally, certain regions of the world are experiencing more frequent or severe flooding. In the Chiriquí Province of Panamá, the town of Cerro Punta has been subject to several severe flooding events in the last few decades. This study aimed to understand perceptions of flood risk amongst residents of Cerro Punta, as well as evaluate physical flood risk in the area. Residents were interviewed regarding their perceptions of flooding as an increasing issue, possible causes, vulnerable areas and populations, and preparedness for future …


Three Land Use Proposals For Geldinganes Framed By The City Of Reykjavik’S Municipal Plan And Climate Neutrality Goals, Emma Hokoda Oct 2018

Three Land Use Proposals For Geldinganes Framed By The City Of Reykjavik’S Municipal Plan And Climate Neutrality Goals, Emma Hokoda

Independent Study Project (ISP) Collection

With global CO2 levels rising every year, climate change is becoming a larger, looming threat. Cities around the world have an important role in reducing the negative impacts of climate change through strategic and sustainable urban planning. The purpose of this study is to conduct an introductory analysis of Geldinganes island and its potential and capacity for land development that will support and expand upon the city of Reykjavik’s 2010-2030 municipal plan and 2040 climate neutrality goals. Within this study three proposals for Geldinganes are considered, the current proposal and two new proposals. The lowest development impact proposal for Geldinganes …


He Effects Of Climate Change On Native Icelandic Plants: A Morphometric Analysis, Maia Jones Oct 2018

He Effects Of Climate Change On Native Icelandic Plants: A Morphometric Analysis, Maia Jones

Independent Study Project (ISP) Collection

This study seeks to evaluate the morphology of three native Icelandic plant species, Alchemilla alpina, Arabidopsis petraea, and Silene uniflora, in order to determine if changing climatic conditions have had an effect on Icelandic vegetation during the twentieth century. I measured herbarium specimens collected during a time period before 1950, and during the period from the late 1960s to the present. Using traditional morphometrics methods, I searched for changes in morphological traits such as plant height, leaf length to width ratio, and leaf size, then performed two-tailed t-tests to analyze the results of the analyses. I found significant changes …


Autonomous Cars, Electric And Hybrid Cars, And Ridesharing: Perceptions Vs. Reality, Christopher W. Eni, Charlie J. Clarke, Danielle A. Wyatt Oct 2018

Autonomous Cars, Electric And Hybrid Cars, And Ridesharing: Perceptions Vs. Reality, Christopher W. Eni, Charlie J. Clarke, Danielle A. Wyatt

Student Publications

Autonomous Cars, Electric and Hybrid Cars, and Ridesharing are all important new technologies in today's society that can have potentially large impacts on the environment in the future. This study was conducted to determine the differences in perceptions of Gettysburg College students regarding Autonomous Cars, Electric and Hybrid Cars, and Ridesharing and the reality of these topics in the real world. This paper also compares the perceptions of Environmental Studies majors/minors to the perceptions of other majors at Gettysburg College. The primary research was conducted by analyzing questions that were a part of a survey consisting of 16 questions which …


Macrophages But Not Astrocytes Harbor Hiv Dna In The Brains Of Hiv-1-Infected Aviremic Individuals On Suppressive Antiretroviral Therapy, Allen Ko, Guobin Kang, Julian B. Hattler, Hadiza I. Galadima, Junfeng Zhang, Qingsheng Li, Woong-Ki Kim Sep 2018

Macrophages But Not Astrocytes Harbor Hiv Dna In The Brains Of Hiv-1-Infected Aviremic Individuals On Suppressive Antiretroviral Therapy, Allen Ko, Guobin Kang, Julian B. Hattler, Hadiza I. Galadima, Junfeng Zhang, Qingsheng Li, Woong-Ki Kim

Community & Environmental Health Faculty Publications

The question of whether the human brain is an anatomical site of persistent HIV-1 infection during suppressive antiretroviral therapy (ART) is critical, but remains unanswered. The presence of virus in the brains of HIV patients whose viral load is effectively suppressed would demonstrate not only the potential for CNS to act as an anatomical HIV reservoir, but also the urgent need to understand the factors contributing to persistent HIV behind the blood-brain barrier. Here, we investigated for the first time the presence of cells harboring HIV DNA and RNA in the brains from subjects with undetectable plasma viral load and …


Influenza Virus Infectivity Is Retained In Aerosols And Droplets Independent Of Relative Humidity, Karen A. Kormuth, Kaisen Lin, Aaron J. Prussin, Eric P. Vejerano, Andrea J. Tiwari, Steve S. Cox, Micheal M. Myerburg, Seema S. Lakdawala, Linsey C. Marr Sep 2018

Influenza Virus Infectivity Is Retained In Aerosols And Droplets Independent Of Relative Humidity, Karen A. Kormuth, Kaisen Lin, Aaron J. Prussin, Eric P. Vejerano, Andrea J. Tiwari, Steve S. Cox, Micheal M. Myerburg, Seema S. Lakdawala, Linsey C. Marr

Faculty Publications

Pandemic and seasonal influenza viruses can be transmitted through aerosols and droplets, in which viruses must remain stable and infectious across a wide range of environmental conditions. Using humidity-controlled chambers, we studied the impact of relative humidity on the stability of 2009 pandemic influenza A(H1N1) virus in suspended aerosols and stationary droplets. Contrary to the prevailing paradigm that humidity modulates the stability of respiratory viruses in aerosols, we found that viruses supplemented with material from the apical surface of differentiated primary human airway epithelial cells remained equally infectious for 1 hour at all relative humidities tested. This sustained infectivity was …


It's About Communities: The Commitment To Promoting A Culturally Competent Environmental Health Workforce, Clint Pinion Jr., Leslie D. Mitchell, Jason W. Marion Sep 2018

It's About Communities: The Commitment To Promoting A Culturally Competent Environmental Health Workforce, Clint Pinion Jr., Leslie D. Mitchell, Jason W. Marion

EKU Faculty and Staff Scholarship

Environmental health and public health are profoundly local. The Association of Environmental Health Academic Programs (AEHAP) firmly agrees and for this reason, it is important to have local environmental health experts who know the pulse of their communities. AEHAP believes in supporting the advanced scientific education of environmental health in these communities through people from these communities. Accordingly, AEHAP has sought to promote and support accredited environmental health programs among a diverse cross-section of the U.S. higher education landscape. AEHAP’s students are diverse in many ways, including socioeconomically, racially, ethnically, and culturally. The value of this approach enhances the overall …


A Review Of Inhalation Exposure To Mold And Adverse Health Outcomes, Amanda S. Persad, Todd Stedeford, Marek Banasik, Tomasz T. Suchecki, Carlos A. Muro-Cacho Aug 2018

A Review Of Inhalation Exposure To Mold And Adverse Health Outcomes, Amanda S. Persad, Todd Stedeford, Marek Banasik, Tomasz T. Suchecki, Carlos A. Muro-Cacho

Florida State University Journal of Land Use and Environmental Law

No abstract provided.


Mycotoxins: Mechanisms For Toxicity And Methods For Identifying Exposed Individuals, Carlos A. Muro-Cach, Todd Stedeford, Marek Banasik, Tomasz T. Suchecki, Amanda S. Persad Aug 2018

Mycotoxins: Mechanisms For Toxicity And Methods For Identifying Exposed Individuals, Carlos A. Muro-Cach, Todd Stedeford, Marek Banasik, Tomasz T. Suchecki, Amanda S. Persad

Florida State University Journal of Land Use and Environmental Law

No abstract provided.


Toxicology And Risk Assessment Of Mycotoxins, Raymond D. Harbison, Todd Stedeford, Marek Banasik, Carlos A. Muro-Cacho Aug 2018

Toxicology And Risk Assessment Of Mycotoxins, Raymond D. Harbison, Todd Stedeford, Marek Banasik, Carlos A. Muro-Cacho

Florida State University Journal of Land Use and Environmental Law

No abstract provided.


Yardwork: A Biography Of An Urban Place By Daniel Coleman, Vivian M. Hansen Aug 2018

Yardwork: A Biography Of An Urban Place By Daniel Coleman, Vivian M. Hansen

The Goose

Review of Daniel Coleman's Yardwork: A Biography of an Urban Place.


The Right To Be Cold: One Woman’S Fight To Protect The Arctic And Save The Planet From Climate Change By Sheila Watt-Cloutier, Leah Van Dyk Aug 2018

The Right To Be Cold: One Woman’S Fight To Protect The Arctic And Save The Planet From Climate Change By Sheila Watt-Cloutier, Leah Van Dyk

The Goose

Review of Sheila Watt-Cloutier's The Right to Be Cold: One Woman's Fight to Protect the Arctic and Save the Planet from Climate Change.


Levels Of Heavy Metals In Selected Facial Cosmetics Marketed In Dar Es Salaam, Tanzania, Joseph Yoeza Naimani Philip, Silvia John, Othman Chande Othman Jul 2018

Levels Of Heavy Metals In Selected Facial Cosmetics Marketed In Dar Es Salaam, Tanzania, Joseph Yoeza Naimani Philip, Silvia John, Othman Chande Othman

Tanzania Journal of Science

The aim of this study was to determine the levels of heavy metals: lead, cadmium, copper, zinc, arsenic and mercury in facial cosmetics (lipstick, lip glossy, facial powder, foundation, eyeliner, eye shadow and mascara) which were purchased randomly in Dar es Salaam, Tanzania. The levels of lead, cadmium, copper and zinc were determined using Atomic Absorption Spectrometry (AAS). The levels of arsenic were determined using Hydride Generation Atomic Absorption Spectrometry (HGAAS), and levels of mercury were determined using Cold Vapour Atomic Absorption Spectrometry. Prior to determination of the concentration of heavy metals, the samples were acid digested. The average order …


Levels Of Heavy Metals In Deposited Dust And Soil From Selected Primary Schools In Dar Es Salaam, Joseph Yoeza Naimani Philip, Eliamini Ismail Mkenga, Othman Chande Othman Jul 2018

Levels Of Heavy Metals In Deposited Dust And Soil From Selected Primary Schools In Dar Es Salaam, Joseph Yoeza Naimani Philip, Eliamini Ismail Mkenga, Othman Chande Othman

Tanzania Journal of Science

The objective of this study was to examine the levels of heavy metals, lead, manganese, nickel, copper, chromium and cadmium in standard one and kindergarten classroom dusts and playing ground soils from selected primary schools along Morogoro road highway (Kimara, Mbezi, Kibamba and Kiluvya primary schools) and away from Morogoro road highway (Makabe, Msumi and Mbopo primary schools) as well as in the Dar es Salaam city center (Uhuru, Mzimuni, Dr. Omari Ali Juma, Manzese and Ubungo National House primary schools), Tanzania. The samples were acid digested and the supernatant analyzed using inductively coupled plasma optical emission spectrometer (ICP-OES). The …


One-Compound-Two-Pharmacophores: Design, Synthesis And Antimalarial Activities Of Chloroquinoline-Cassiarin, Thobias M. Kalenga, Monica M. Ndoile, Quintino A. Mgani Jul 2018

One-Compound-Two-Pharmacophores: Design, Synthesis And Antimalarial Activities Of Chloroquinoline-Cassiarin, Thobias M. Kalenga, Monica M. Ndoile, Quintino A. Mgani

Tanzania Journal of Science

This paper describes the design and synthesis of a potential antimalarial compound, chloroquinoline-cassiarin (6) using 4,7-dichloroquinoline and the natural product barakol (1) extracted from the leaves of Cassia siamea as starting materials. In this paper a one compound-two-pharmacophores concept is introduced in which coupling of two known pharmacophores into one has been described. The concept is not only useful to organic synthesis but also to drug development researches. The synthesized compound 6 exhibited potent in vitro antimalarial activity at IC50 = 0.51 µM, and low toxicity where at 20 µM, 80% viability of HeLa cells was observed.


Cross Photoreaction Of Glyoxylic And Pyruvic Acids In Model Aqueous Aerosol, Sha-Sha Xia, Alexis J. Eugene, Marcelo I. Guzman Jul 2018

Cross Photoreaction Of Glyoxylic And Pyruvic Acids In Model Aqueous Aerosol, Sha-Sha Xia, Alexis J. Eugene, Marcelo I. Guzman

Chemistry Faculty Publications

Aerosols of variable composition, size, and shape are associated with public health concerns as well as with light-particle interactions that play a role in the energy balance of the atmosphere. Photochemical reactions of 2-oxocarboxylic acids in the aqueous phase are now known to contribute to the total secondary organic aerosol (SOA) budget. This work explores the cross reaction of glyoxylic acid (GA) and pyruvic acid (PA) in water, the two most abundant 2-oxocarboxylic acids in the atmosphere, under solar irradiation and dark thermal aging steps. During irradiation, PA and GA are excited and initiate proton-coupled electron transfer or hydrogen abstraction …


Aerosol Microdroplets Exhibit A Stable Ph Gradient, Haoran Wei, Eric P. Vejerano, Weinan Leng, Qishen Haung, Marjorie R. Willner, Linsey C. Marr, Peter J. Vikesland Jul 2018

Aerosol Microdroplets Exhibit A Stable Ph Gradient, Haoran Wei, Eric P. Vejerano, Weinan Leng, Qishen Haung, Marjorie R. Willner, Linsey C. Marr, Peter J. Vikesland

Faculty Publications

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.