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1. Particulate Organic Carbon Deconstructed: Molecular and Chemical Composition of Particulate Organic Carbon in the Ocean

   https://doi.org/10.3389/fmars.2020.00518  

   Kharbush, Jenan J.; Close, Hilary G.; Van Mooy, Benjamin A.; Arnosti, Carol; Smittenberg, Rienk H.; Le Moigne, Frédéric A.; Mollenhauer, Gesine; Scholz-Böttcher, Barbara; Obreht, Igor; Koch, Boris P.; et al (June 2020, Frontiers in Marine Science)
2. Fine particulate matter and polycystic ovarian morphology

   https://doi.org/10.1186/s12940-022-00835-1  

   Fruh, Victoria; Cheng, Jay Jojo; Aschengrau, Ann; Mahalingaiah, Shruthi; Lane, Kevin J. (December 2022, Environmental Health)

   Abstract Background Polycystic ovary morphology (PCOM) is an ultrasonographic finding that can be present in women with ovulatory disorder and oligomenorrhea due to hypothalamic, pituitary, and ovarian dysfunction. While air pollution has emerged as a possible disrupter of hormone homeostasis, limited research has been conducted on the association between air pollution and PCOM. Methods We conducted a longitudinal cohort study using electronic medical records data of 5,492 women with normal ovaries at the first ultrasound that underwent a repeated pelvic ultrasound examination during the study period (2004–2016) at Boston Medical Center. Machine learning text algorithms classified PCOM by ultrasound. We used geocoded home address to determine the ambient annual average PM 2.5 exposures and categorized into tertiles of exposure. We used Cox Proportional Hazards models on complete data ( n  = 3,994), adjusting for covariates, and additionally stratified by race/ethnicity and body mass index (BMI). Results Cumulative exposure to PM 2.5 during the study ranged from 4.9 to 17.5 µg/m 3 (mean = 10.0 μg/m 3 ). On average, women were 31 years old and 58% were Black/African American. Hazard ratios and 95% confidence intervals (CI) comparing the second and third PM 2.5 exposure tertile vs. the reference tertile were 1.12 (0.88, 1.43) and 0.89 (0.62, 1.28), respectively. No appreciable differences were observed across race/ethnicity. Among women with BMI ≥ 30 kg/m 2 , we observed weak inverse associations with PCOM for the second (HR: 0.93, 95% CI: 0.66, 1.33) and third tertiles (HR: 0.89, 95% CI: 0.50, 1.57). Conclusions In this study of reproductive-aged women, we observed little association between PM 2.5 concentrations and PCOM incidence. No dose response relationships were observed nor were estimates appreciably different across race/ethnicity within this clinically sourced cohort. 

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3. Acoustofluidic Synthesis of Particulate Nanomaterials

   https://doi.org/10.1002/advs.201900913  

   Huang, Po‐Hsun; Zhao, Shuaiguo; Bachman, Hunter; Nama, Nitesh; Li, Zhishang; Chen, Chuyi; Yang, Shujie; Wu, Mengxi; Zhang, Steven_Peiran; Huang, Tony_Jun (August 2019, Advanced Science)

   Abstract Synthesis of nanoparticles and particulate nanomaterials with tailored properties is a central step toward many applications ranging from energy conversion and imaging/display to biosensing and nanomedicine. While existing microfluidics‐based synthesis methods offer precise control over the synthesis process, most of them rely on passive, partial mixing of reagents, which limits their applicability and potentially, adversely alter the properties of synthesized products. Here, an acoustofluidic (i.e., the fusion of acoustic and microfluidics) synthesis platform is reported to synthesize nanoparticles and nanomaterials in a controllable, reproducible manner through acoustic‐streaming‐based active mixing of reagents. The acoustofluidic strategy allows for the dynamic control of the reaction conditions simply by adjusting the strength of the acoustic streaming. With this platform, the synthesis of versatile nanoparticles/nanomaterials is demonstrated including the synthesis of polymeric nanoparticles, chitosan nanoparticles, organic–inorganic hybrid nanomaterials, metal–organic framework biocomposites, and lipid‐DNA complexes. The acoustofluidic synthesis platform, when incorporated with varying flow rates, compositions, or concentrations of reagents, will lend itself unprecedented flexibility in establishing various reaction conditions and thus enable the synthesis of versatile nanoparticles and nanomaterials with prescribed properties. 

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4. Droplet detachment and pinch-off of bidisperse particulate suspensions

   https://doi.org/10.1039/D1SM00593F  

   Thiévenaz, Virgile; Rajesh, Sreeram; Sauret, Alban (January 2021, Soft Matter)

   null (Ed.)

   When a droplet is generated, the ligament connecting the drop to the nozzle thins down and eventually pinches off. Adding solid particles to the liquid phase leads to a more complex dynamic, notably by increasing the shear viscosity. Moreover, it introduces an additional length scale to the system, the diameter of the particles, which eventually becomes comparable to the diameter of the ligament. In this paper, we experimentally investigate the thinning and pinch-off of drops of suspensions with two different sizes of particles. We characterize the thinning for different particle size ratios and different proportions of small particles. Long before the pinch-off, the thinning rate is that of an equivalent liquid whose viscosity is that of the suspension. Later, when the ligament thickness approaches the size of the large particles, the thinning accelerates and leads to an early pinch-off. We explain how the bidisperse particle size distribution lowers the viscosity by making the packing more efficient, which speeds up the thinning. This result can be used to predict the dynamics of droplet formation with bidisperse suspensions. 

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5. Dip coating of bidisperse particulate suspensions

   https://doi.org/10.1017/jfm.2022.79  

   Jeong, Deok-Hoon; Lee, Michael Ka; Thiévenaz, Virgile; Bazant, Martin Z.; Sauret, Alban (April 2022, Journal of Fluid Mechanics)

   Dip coating consists of withdrawing a substrate from a bath to coat it with a thin liquid layer. This process is well understood for homogeneous fluids, but heterogeneities, such as particles dispersed in liquid, lead to more complex situations. Indeed, particles introduce a new length scale, their size, in addition to the thickness of the coating film. Recent studies have shown that, at first order, the thickness of the coating film for monodisperse particles can be captured by an effective capillary number based on the viscosity of the suspension, providing that the film is thicker than the particle diameter. However, suspensions involved in most practical applications are polydisperse, characterized by a wide range of particle sizes, introducing additional length scales. In this study, we investigate the dip coating of suspensions having a bimodal size distribution of particles. We show that the effective viscosity approach is still valid in the regime where the coating film is thicker than the diameter of the largest particles, although bidisperse suspensions are less viscous than monodisperse suspensions of the same solid fraction. We also characterize the intermediate regime that consists of a heterogeneous coating layer and where the composition of the film is different from the composition of the bath. A model to predict the probability of entraining the particles in the liquid film depending on their sizes is proposed and captures our measurements. In this regime, corresponding to a specific range of withdrawal velocities, capillarity filters the large particles out of the film. 

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