Allan K. Bertram
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View article: Two-Phase Morphology and Drastic Viscosity Changes in Biomass Burning Organic Aerosol After Hydroxyl Radical Aging
Two-Phase Morphology and Drastic Viscosity Changes in Biomass Burning Organic Aerosol After Hydroxyl Radical Aging Open
Understanding the impact of wildfire-derived biomass burning organic aerosol (BBOA) on air quality, climate, and atmospheric chemistry requires knowledge of its phase behavior and viscosity – properties that remain poorly characterized aft…
View article: At least seven orders of magnitude viscosity variability in biomass burning organic aerosol from smoldering eucalyptus smoke
At least seven orders of magnitude viscosity variability in biomass burning organic aerosol from smoldering eucalyptus smoke Open
Uncontrolled wildfires in Australian eucalyptus forests emit large amounts of smoke, primarily composed of biomass burning organic aerosol (BBOA). Although BBOA viscosity has been studied for other fuels, it remains uncharacterized for euc…
View article: ICE BINDING PROTEIN ACTIVITY IS COMMON AMONG TEMPERATE PACIFIC INTERTIDAL INVERTEBRATES
ICE BINDING PROTEIN ACTIVITY IS COMMON AMONG TEMPERATE PACIFIC INTERTIDAL INVERTEBRATES Open
Intertidal invertebrates often adopt freeze tolerance as a strategy to survive winter low tides, but the physiological mechanisms by which intertidal species survive freezing are not well understood. Ice binding proteins (IBPs) may play an…
View article: SeParation of Ice Nuclei via Density Layers (SPINDL): A new method for characterizing ice nuclei using density gradient centrifugation
SeParation of Ice Nuclei via Density Layers (SPINDL): A new method for characterizing ice nuclei using density gradient centrifugation Open
Atmospheric ice nucleating substances (INSs) play a crucial role in ice cloud formation above -35°C, impacting cloud radiative properties, cloud lifetime, and the hydrological cycle. Characterizing inorganic (e.g., mineral dusts, volc…
View article: Viscosity and phase state of wildfire smoke particles in the stratosphere from pyrocumulonimbus events: an initial assessment
Viscosity and phase state of wildfire smoke particles in the stratosphere from pyrocumulonimbus events: an initial assessment Open
Understanding the viscosity and phase state of biomass-burning organic aerosol (BBOA) from wildfires and pyrocumulonimbus (pyroCb) events in the stratosphere is critical for predicting their role in stratospheric multiphase chemistry and o…
View article: Characterization of Woodsmoke Generated in the Air Pollution Exposure Lab and Comparison to Diesel Exhaust
Characterization of Woodsmoke Generated in the Air Pollution Exposure Lab and Comparison to Diesel Exhaust Open
To address the increasing concern of woodsmoke (WS) and better understand its effects on human health, a woodsmoke generation system was built in the Air Pollution Exposure Laboratory to facilitate future controlled human exposure studies.…
View article: Viscosity and phase state of wildfire smoke particles in the stratosphere from pyrocumulonimbus events: an initial assessment
Viscosity and phase state of wildfire smoke particles in the stratosphere from pyrocumulonimbus events: an initial assessment Open
Understanding the viscosity and phase state of biomass-burning organic aerosol (BBOA) from wildfires and pyrocumulonimbus (pyroCb) events in the stratosphere is critical for predicting their role in stratospheric multiphase chemistry and o…
View article: Viscosity and phase state of wildfire smoke particles in the stratosphere from pyrocumulonimbus events: an initial assessment
Viscosity and phase state of wildfire smoke particles in the stratosphere from pyrocumulonimbus events: an initial assessment Open
Understanding the viscosity and phase state of biomass-burning organic aerosol (BBOA) from wildfires and pyrocumulonimbus (pyroCb) events in the stratosphere is critical for predicting their role in stratospheric multiphase chemistry and o…
View article: Two-phase morphology and drastic viscosity changes in biomass burning organic aerosol after hydroxyl radical aging
Two-phase morphology and drastic viscosity changes in biomass burning organic aerosol after hydroxyl radical aging Open
Aged biomass burning organic aerosol has two phases and sees a ≥10 000× increase in viscosity after aging for 5 days.
View article: Viscosity of aqueous ammonium nitrate–organic particles: equilibrium partitioning may be a reasonable assumption for most tropospheric conditions
Viscosity of aqueous ammonium nitrate–organic particles: equilibrium partitioning may be a reasonable assumption for most tropospheric conditions Open
The viscosity of aerosol particles determines the critical mixing time of gas–particle partitioning of volatile compounds in the atmosphere. The partitioning of the semi-volatile ammonium nitrate (NH4NO3) might alter the viscosity of highl…
View article: High viscosity and two phases observed over a range of relative humidities in biomass burning organic aerosol from Canadian wildfires
High viscosity and two phases observed over a range of relative humidities in biomass burning organic aerosol from Canadian wildfires Open
Biomass burning organic aerosol (BBOA) is a major contributor to organic aerosol in the atmosphere. The impacts of BBOA on climate and health depend strongly on their physicochemical properties, including viscosity and phase behaviour (num…
View article: Characterization and integration of a new oxidative flow reactor for use in in vitro and human exposure systems with diesel exhaust and other aerosol
Characterization and integration of a new oxidative flow reactor for use in in vitro and human exposure systems with diesel exhaust and other aerosol Open
Freshly emitted air pollutants may not represent real-world exposure conditions in human studies, especially for communities exposed to aged air pollutants. This study presents the design and characterization of a new oxidative flow reacto…
View article: Viscosity and phase state of wildfire smoke particles in the stratosphere from pyrocumulonimbus events: an initial assessment
Viscosity and phase state of wildfire smoke particles in the stratosphere from pyrocumulonimbus events: an initial assessment Open
Large wildfires periodically inject massive amounts of biomass burning organic aerosol (BBOA) into the stratosphere (~15 km ≤ altitude ≤ 50 km) via pyrocumulonimbus (pyroCb) events. These aerosols may remain aloft for many months and engag…
View article: Microplastic Particles Contain Ice Nucleation Sites That Can Be Inhibited by Atmospheric Aging
Microplastic Particles Contain Ice Nucleation Sites That Can Be Inhibited by Atmospheric Aging Open
Recent research has shown that microplastics are widespread in the atmosphere. However, we know little about their ability to nucleate ice and their impact on ice formation in clouds. Ice nucleation by microplastics could also limit their …
View article: An Ultrahydrating Polymer that Protects Protein Therapeutics and RNA‐Lipid Nanoparticles Against Freezing, Heat and Lyophilization Stress
An Ultrahydrating Polymer that Protects Protein Therapeutics and RNA‐Lipid Nanoparticles Against Freezing, Heat and Lyophilization Stress Open
RNA and protein‐based therapeutics constitute almost half of recent drug approvals and receive considerable attention within biotechnology industries. Ensuring their stability and longevity in the context of heat, freezing, and lyophilizat…
View article: Microplastic particles contain ice nucleation sites that can be inhibited by atmospheric aging
Microplastic particles contain ice nucleation sites that can be inhibited by atmospheric aging Open
Recent research has shown that microplastics are widespread in the atmosphere. However, we know little about their ability to nucleate ice and their impact on ice formation in clouds. Ice nucleation by microplastics could also limit their …
View article: Secondary organic aerosol from biomass burning phenolic compounds and nitrate radicals can be highly viscous over a wide relative humidity range
Secondary organic aerosol from biomass burning phenolic compounds and nitrate radicals can be highly viscous over a wide relative humidity range Open
Biomass burning events, including wildfires, can emit large amounts of phenolic compounds such as guaiacol. These phenolic compounds can undergo oxidation by nitrate radicals (NO3) to form secondary organic aerosol (SOA). Viscosity and hyg…
View article: Comment on egusphere-2024-1459
Comment on egusphere-2024-1459 Open
Abstract. The viscosity of aerosol particles determines the critical mixing time of gas–particle partitioning of volatile compounds in the atmosphere. The partitioning of the semi-volatile ammonium nitrate (NH4N…
View article: Viscosity of aqueous ammonium nitrate–organic particles: Equilibrium partitioning may be a reasonable assumption for most tropospheric conditions
Viscosity of aqueous ammonium nitrate–organic particles: Equilibrium partitioning may be a reasonable assumption for most tropospheric conditions Open
The viscosity of aerosol particles determines the critical mixing time of gas–particle partitioning of volatile compounds in the atmosphere. The partitioning of the semi-volatile ammonium nitrate (NH4NO3) might alter the viscosity of highl…
View article: Biomass burning organic aerosol (BBOA) from wildfires has multiple phases and is more viscous than laboratory generated BBOA
Biomass burning organic aerosol (BBOA) from wildfires has multiple phases and is more viscous than laboratory generated BBOA Open
Biomass burning organic aerosol (BBOA) is a major contributor to organic aerosol in the atmosphere. The impacts of BBOA on climate and health depend strongly on their physicochemical properties, including viscosity and phase behaviour (num…
View article: A method for separating and quantifying organic and inorganic ice nucleating substances in atmospheric samples based on density gradient centrifugation
A method for separating and quantifying organic and inorganic ice nucleating substances in atmospheric samples based on density gradient centrifugation Open
Ice nucleating substances (INSs) influence the properties and frequencies of ice and mixed-phase clouds in the atmosphere, and hence, climate and the hydrological cycle. INSs can be classified as inorganic (e.g., mineral dust, volcanic ash…
View article: A method for separating and quantifying organic and inorganic ice nucleating substances in atmospheric samples based on density gradient centrifugation
A method for separating and quantifying organic and inorganic ice nucleating substances in atmospheric samples based on density gradient centrifugation Open
Ice nucleating substances (INSs) influence the properties and frequencies of ice and mixed-phase clouds in the atmosphere, and hence, climate and the hydrological cycle. INSs can be classified as inorganic (e.g., mineral dust, volcanic ash…
View article: Microplastic particles contain ice nucleation sites that can be deactivated by atmospheric aging
Microplastic particles contain ice nucleation sites that can be deactivated by atmospheric aging Open
Recent research has shown that microplastics are widespread in the atmosphere. However, we know little about their ability to nucleate ice and impact cloud glaciation. Ice nucleation by microplastics could also limit their long-range trans…
View article: Heterogeneous Ice Nucleation of Microplastics before and after Oxidation
Heterogeneous Ice Nucleation of Microplastics before and after Oxidation Open
Many recent studies point to the environmental threat posed by microplastic pollution, both in waterways and as transmitted globally in the atmosphere.1,2 Airborne microplastics impact the climate by the direct absorption and scattering of…
View article: Modeling Iron-Copper Cycling in Photochemically Aged Organic Aerosol Particles
Modeling Iron-Copper Cycling in Photochemically Aged Organic Aerosol Particles Open
Photochemical aging of redox-active transition metals in organic aerosol (OA) particles contributesto an increase in oxidative potential and changes their atmospheric fate. We evaluated thepoorly characterized role of copper as a highly em…
View article: Boiling of catechol secondary organic aerosol when heated to mild temperatures (36-52 °C) due to acetone and carbon dioxide formation and high viscosity
Boiling of catechol secondary organic aerosol when heated to mild temperatures (36-52 °C) due to acetone and carbon dioxide formation and high viscosity Open
Thermal desorption measurements, including thermal desorption mass spectrometry, are often used to determine the volatility and chemical composition of secondary organic aerosol (SOA). Accurately interpreting such measurements requires und…
View article: The Effects of Aminium and Ammonium Cations on the Ice Nucleation Activity of K‐Feldspar
The Effects of Aminium and Ammonium Cations on the Ice Nucleation Activity of K‐Feldspar Open
Mineral dust is one of the most abundant types of ice nucleating particles in the atmosphere. During atmospheric transport, mineral dust particles can become coated with inorganic and organic solutes, which can impact their ice nucleation …
View article: Insect Infestation Increases Viscosity of Biogenic Secondary Organic Aerosol
Insect Infestation Increases Viscosity of Biogenic Secondary Organic Aerosol Open
Plant stress alters emissions of volatile organic compounds. However, little is known about how this could influence climate-relevant properties of secondary organic aerosol (SOA), particularly from complex mixtures such as real plant emis…
View article: Liquid-liquid phase separation and viscosity in biomass burning organic aerosol and climatic impacts
Liquid-liquid phase separation and viscosity in biomass burning organic aerosol and climatic impacts Open
Smoke particles generated by burning biomass consist mainly of organic aerosol, referred to as biomass-burning organic aerosol (BBOA). BBOA influences the climate by scattering and absorbing solar radiation or acting as nuclei for cloud fo…
View article: Not all types of secondary organic aerosol mix: two phases observed when mixing different secondary organic aerosol types
Not all types of secondary organic aerosol mix: two phases observed when mixing different secondary organic aerosol types Open
Atmospheric aerosol particles play an important role for air quality and climate. Secondary organic aerosol (SOA) make up a significant mass fraction of these particles. SOA particles mostly forms from oxidation of gases, followed by gas-p…