Size, Shape, and Phase of Nanoscale Uric Acid Particles

Toward an Understanding of Uric Acid Particle Dissolution: Surface and Bulk-Driven Water Activity

“…Particles below 180 nm shrink when exposed to subsaturated conditions (GF < 1). This is attributed to the nonspherical shape of smaller size particles; 17 as water condenses on the surface, the particle collapses, and the wet droplet mobility diameter is smaller than the initially measured dry particle mobility diameter size. This phenomenon has been observed for organic aerosols and mixtures of organic and inorganic aerosols.…”

“…Thus, a shape-factor correction is necessary and applied to all subsequent analyses. 17 The experimental setup for shape factor and CCN measurement is shown in the Supporting Section (Figures S2 and S4, respectively). The volume equivalent diameter (d ve dry ) corresponding to each critical dry particle mobility diameter was determined (Figure S3).…”

“…Bulk uric acid was dissolved in ultrapurified water, nebulized, and dried using a diffusion dryer to form nanoscale uric acid particles. Droplet-dried nanoscale uric acid particles are shown to be amorphous and nonspherical (Figure S1) while bulk uric acid samples have been observed to be crystalline . Droplet-dried, submicrometer-sized amorphous particles were exposed to subsaturated conditions in HTDMA and supersaturated conditions inside a CCNC while the bulk crystalline sample was studied using the VSA technique as described in more detail below.…”

Toward an Understanding of Uric Acid Particle Dissolution: Surface and Bulk-Driven Water Activity

“…Particles below 180 nm shrink when exposed to subsaturated conditions (GF < 1). This is attributed to the nonspherical shape of smaller size particles; 17 as water condenses on the surface, the particle collapses, and the wet droplet mobility diameter is smaller than the initially measured dry particle mobility diameter size. This phenomenon has been observed for organic aerosols and mixtures of organic and inorganic aerosols.…”

“…Thus, a shape-factor correction is necessary and applied to all subsequent analyses. 17 The experimental setup for shape factor and CCN measurement is shown in the Supporting Section (Figures S2 and S4, respectively). The volume equivalent diameter (d ve dry ) corresponding to each critical dry particle mobility diameter was determined (Figure S3).…”

“…Bulk uric acid was dissolved in ultrapurified water, nebulized, and dried using a diffusion dryer to form nanoscale uric acid particles. Droplet-dried nanoscale uric acid particles are shown to be amorphous and nonspherical (Figure S1) while bulk uric acid samples have been observed to be crystalline . Droplet-dried, submicrometer-sized amorphous particles were exposed to subsaturated conditions in HTDMA and supersaturated conditions inside a CCNC while the bulk crystalline sample was studied using the VSA technique as described in more detail below.…”

The Role of Organic Vapor in the Water Uptake of Organic Aerosols

“…To generate aerosols, a constant output collision nebulizer (atomizer; TSI 3076) was utilized (flow rate: ∼2.0 L min –1 ) as previously described in CCN literature. ,,, The wet aerosols generated were dried (<5% RH) using dryers containing water absorbent silica gel. To ensure that the aerosol particles are dried to <5% RH, the silica gel was oven-dried prior to each experiment, and the % RH was validated using an RH meter downstream of the drying chamber . The resultant dry aerosols were then investigated under two different experimental setups, namely, the CCNC setup (measurements under a supersaturated environment) and the H-TDMA setup (measurements under a subsaturated environment).…”

“…A detailed experimental setup is provided in Figure S4. The working principles of this experimental setup have been discussed extensively in literature. ,− In sum, the dried aerosol stream (flow rate = 0.3 L min –1 ; sheath flow to aerosol flow ratio = 10:1) was passed through the AAC where 10 different particle aerodynamic diameters ( d ae ) were size-selected between 90 and 180 nm, with increments of 10 nm. The monodisperse particles with a selected diameter size were then passed into the DMA and the CPC where the corresponding mobility diameter ( d mo ) was measured.…”

Toward an Understanding of Uric Acid Particle Dissolution: Surface and Bulk-Driven Water Activity

“…Particles below 180 nm shrink when exposed to subsaturated conditions (GF < 1). This is attributed to the nonspherical shape of smaller size particles; 17 as water condenses on the surface, the particle collapses, and the wet droplet mobility diameter is smaller than the initially measured dry particle mobility diameter size. This phenomenon has been observed for organic aerosols and mixtures of organic and inorganic aerosols.…”

“…Thus, a shape-factor correction is necessary and applied to all subsequent analyses. 17 The experimental setup for shape factor and CCN measurement is shown in the Supporting Section (Figures S2 and S4, respectively). The volume equivalent diameter (d ve dry ) corresponding to each critical dry particle mobility diameter was determined (Figure S3).…”

“…Bulk uric acid was dissolved in ultrapurified water, nebulized, and dried using a diffusion dryer to form nanoscale uric acid particles. Droplet-dried nanoscale uric acid particles are shown to be amorphous and nonspherical (Figure S1) while bulk uric acid samples have been observed to be crystalline . Droplet-dried, submicrometer-sized amorphous particles were exposed to subsaturated conditions in HTDMA and supersaturated conditions inside a CCNC while the bulk crystalline sample was studied using the VSA technique as described in more detail below.…”

The Role of Organic Vapor in the Water Uptake of Organic Aerosols

“…To generate aerosols, a constant output collision nebulizer (atomizer; TSI 3076) was utilized (flow rate: ∼2.0 L min –1 ) as previously described in CCN literature. ,,, The wet aerosols generated were dried (<5% RH) using dryers containing water absorbent silica gel. To ensure that the aerosol particles are dried to <5% RH, the silica gel was oven-dried prior to each experiment, and the % RH was validated using an RH meter downstream of the drying chamber . The resultant dry aerosols were then investigated under two different experimental setups, namely, the CCNC setup (measurements under a supersaturated environment) and the H-TDMA setup (measurements under a subsaturated environment).…”

“…A detailed experimental setup is provided in Figure S4. The working principles of this experimental setup have been discussed extensively in literature. ,− In sum, the dried aerosol stream (flow rate = 0.3 L min –1 ; sheath flow to aerosol flow ratio = 10:1) was passed through the AAC where 10 different particle aerodynamic diameters ( d ae ) were size-selected between 90 and 180 nm, with increments of 10 nm. The monodisperse particles with a selected diameter size were then passed into the DMA and the CPC where the corresponding mobility diameter ( d mo ) was measured.…”

Toward an Understanding of Uric Acid Particle Dissolution: Surface and Bulk-Driven Water Activity

“…Particles below 180 nm shrink when exposed to subsaturated conditions (GF < 1). This is attributed to the nonspherical shape of smaller size particles; 17 as water condenses on the surface, the particle collapses, and the wet droplet mobility diameter is smaller than the initially measured dry particle mobility diameter size. This phenomenon has been observed for organic aerosols and mixtures of organic and inorganic aerosols.…”

“…Thus, a shape-factor correction is necessary and applied to all subsequent analyses. 17 The experimental setup for shape factor and CCN measurement is shown in the Supporting Section (Figures S2 and S4, respectively). The volume equivalent diameter (d ve dry ) corresponding to each critical dry particle mobility diameter was determined (Figure S3).…”

“…Bulk uric acid was dissolved in ultrapurified water, nebulized, and dried using a diffusion dryer to form nanoscale uric acid particles. Droplet-dried nanoscale uric acid particles are shown to be amorphous and nonspherical (Figure S1) while bulk uric acid samples have been observed to be crystalline . Droplet-dried, submicrometer-sized amorphous particles were exposed to subsaturated conditions in HTDMA and supersaturated conditions inside a CCNC while the bulk crystalline sample was studied using the VSA technique as described in more detail below.…”

The Role of Organic Vapor in the Water Uptake of Organic Aerosols

“…To generate aerosols, a constant output collision nebulizer (atomizer; TSI 3076) was utilized (flow rate: ∼2.0 L min –1 ) as previously described in CCN literature. ,,, The wet aerosols generated were dried (<5% RH) using dryers containing water absorbent silica gel. To ensure that the aerosol particles are dried to <5% RH, the silica gel was oven-dried prior to each experiment, and the % RH was validated using an RH meter downstream of the drying chamber . The resultant dry aerosols were then investigated under two different experimental setups, namely, the CCNC setup (measurements under a supersaturated environment) and the H-TDMA setup (measurements under a subsaturated environment).…”

“…A detailed experimental setup is provided in Figure S4. The working principles of this experimental setup have been discussed extensively in literature. ,− In sum, the dried aerosol stream (flow rate = 0.3 L min –1 ; sheath flow to aerosol flow ratio = 10:1) was passed through the AAC where 10 different particle aerodynamic diameters ( d ae ) were size-selected between 90 and 180 nm, with increments of 10 nm. The monodisperse particles with a selected diameter size were then passed into the DMA and the CPC where the corresponding mobility diameter ( d mo ) was measured.…”