More Like this

1. Membrane Characterization with Model-Based Design of Experiments

   https://doi.org/10.1016/B978-0-323-85159-6.50143-3  

   Liu, X.; Wang, J.; Ouimet, J.A.; Phillip, W.A.; Dowling, A.W. (July 2022, Computer aided chemical engineering)

   Yamashita, Y.; Kano, M. (Ed.)

   Membrane characterization provides essential information for the scale-up, design, and optimization of new separation systems. We recently proposed the diafiltration apparatus for high-throughput analysis (DATA), which enables a 5-times reduction in the time, energy, and the number of experiments necessary to characterize membrane transport properties. This paper applies formal model-based design of experiments (MBDoE) techniques to further analyse and optimize DATA. For example, the eigenvalues and eigenvectors of the Fisher Information Matrix (FIM) show dynamic diafiltration experiments improve parameter identifiability by 3 orders of magnitude compared to traditional filtration experiments. Moreover, continuous retentate conductivity measurements in DATA improve A-, D-, E-, and ME-optimal MBDoE criteria by between 6 % and 32 %. Using these criteria, we identify pressure and initial concentrations conditions that maximize parameter precision and remove correlations. 

   more » « less
2. Ultra‐Sharp Nanowire Arrays Natively Permeate, Record, and Stimulate Intracellular Activity in Neuronal and Cardiac Networks

   https://doi.org/10.1002/adfm.202108378  

   Liu, Ren; Lee, Jihwan; Tchoe, Youngbin; Pre, Deborah; Bourhis, Andrew_M; D'Antonio‐Chronowska, Agnieszka; Robin, Gaelle; Lee, Sang_Heon; Ro, Yun_Goo; Vatsyayan, Ritwik; et al (November 2021, Advanced Functional Materials)

   Abstract Intracellular access with high spatiotemporal resolution can enhance the understanding of how neurons or cardiomyocytes regulate and orchestrate network activity and how this activity can be affected with pharmacology or other interventional modalities. Nanoscale devices often employ electroporation to transiently permeate the cell membrane and record intracellular potentials, which tend to decrease rapidly with time. Here, one reports innovative scalable, vertical, ultrasharp nanowire arrays that are individually addressable to enable long‐term, native recordings of intracellular potentials. One reports electrophysiological recordings that are indicative of intracellular access from 3D tissue‐like networks of neurons and cardiomyocytes across recording days and that do not decrease to extracellular amplitudes for the duration of the recording of several minutes. The findings are validated with cross‐sectional microscopy, pharmacology, and electrical interventions. The experiments and simulations demonstrate that the individual electrical addressability of nanowires is necessary for high‐fidelity intracellular electrophysiological recordings. This study advances the understanding of and control over high‐quality multichannel intracellular recordings and paves the way toward predictive, high‐throughput, and low‐cost electrophysiological drug screening platforms. 

   more » « less
3. Airborne and ground-based observations of ammonium-nitrate-dominated aerosols in a shallow boundary layer during intense winter pollution episodes in northern Utah

   https://doi.org/10.5194/acp-18-17259-2018  

   Franchin, Alessandro; Fibiger, Dorothy L.; Goldberger, Lexie; McDuffie, Erin E.; Moravek, Alexander; Womack, Caroline C.; Crosman, Erik T.; Docherty, Kenneth S.; Dube, William P.; Hoch, Sebastian W.; et al (January 2018, Atmospheric Chemistry and Physics)

   Abstract. Airborne and ground-based measurements of aerosol concentrations, chemicalcomposition, and gas-phase precursors were obtained in three valleys innorthern Utah (USA). The measurements were part of the Utah Winter FineParticulate Study (UWFPS) that took place in January–February 2017. Totalaerosol mass concentrations of PM₁ were measured from a Twin Otteraircraft, with an aerosol mass spectrometer (AMS). PM₁ concentrationsranged from less than 2µgm⁻³ during clean periods to over100µgm⁻³ during the most polluted episodes, consistent withPM_2.5 total mass concentrations measured concurrently at groundsites. Across the entire region, increases in total aerosol mass above∼2µgm⁻³ were associated with increases in theammonium nitrate mass fraction, clearly indicating that the highest aerosolmass loadings in the region were predominantly attributable to an increase inammonium nitrate. The chemical composition was regionally homogenous fortotal aerosol mass concentrations above 17.5µgm⁻³, with 74±5% (average±standard deviation) ammonium nitrate, 18±3%organic material, 6±3% ammonium sulfate, and 2±2%ammonium chloride. Vertical profiles of aerosol mass and volume in the regionshowed variable concentrations with height in the polluted boundary layer.Higher average mass concentrations were observed within the first few hundredmeters above ground level in all three valleys during pollution episodes. Gas-phase measurements of nitric acid (HNO₃) and ammonia (NH₃) duringthe pollution episodes revealed that in the Cache and Utah valleys, partitioningof inorganic semi-volatiles to the aerosol phase was usually limited by theamount of gas-phase nitric acid, with NH₃ being in excess. The inorganicspecies were compared with the ISORROPIA thermodynamic model. Total inorganicaerosol mass concentrations were calculated for various decreases in totalnitrate and total ammonium. For pollution episodes, our simulations of a50% decrease in total nitrate lead to a 46±3% decrease in totalPM₁ mass. A simulated 50% decrease in total ammonium leads to a36±17%µgm⁻³ decrease in total PM₁ mass, over the entirearea of the study. Despite some differences among locations, ourresults showed a higher sensitivity to decreasing nitric acid concentrationsand the importance of ammonia at the lowest total nitrate conditions. In theSalt Lake Valley, both HNO₃ and NH₃ concentrations controlledaerosol formation. 

   more » « less
4. Multiple particle tracking microrheology measured using bi-disperse probe diameters

   https://doi.org/10.1039/C8SM01098F  

   Wehrman, Matthew D.; Lindberg, Seth; Schultz, Kelly M. (January 2018, Soft Matter)

   Multiple particle tracking microrheology (MPT) is a powerful tool for quantitatively characterizing rheological properties of soft matter. Traditionally, MPT uses a single particle size to characterize rheological properties. But in complex systems, MPT measurements with a single size particle can characterize distinct properties that are linked to the materials' length scale dependent structure. By varying the size of probes, MPT can measure the properties associated with different length scales within a material. We develop a technique to simultaneously track a bi-disperse population of probe particles. 0.5 and 2 μm particles are embedded in the same sample and these particle populations are tracked separately using a brightness-based squared radius of gyration, R g 2 . Bi-disperse MPT is validated by measuring the viscosity of glycerol samples at varying concentrations. Bi-disperse MPT measurements agree well with literature values. This technique then characterizes a homogeneous poly(ethylene glycol)-acrylate:poly(ethylene glycol)-dithiol gelation. The critical relaxation exponent and critical gelation time are consistent and agree with previous measurements using a single particle. Finally, degradation of a heterogeneous hydrogenated castor oil colloidal gel is characterized. The two particle sizes measure a different value of the critical relaxation exponent, indicating that they are probing different structures. Analysis of material heterogeneity shows measured heterogeneity is dependent on probe size indicating that each particle is measuring rheological evolution of a length scale dependent structure. Overall, bi-disperse MPT increases the amount of information gained in a single measurement, enabling more complete characterization of complex systems that range from consumer care products to biological materials. 

   more » « less
5. Characterizing the Occurrence and Spatial Heterogeneity of Liquid, Ice, and Mixed Phase Low‐Level Clouds Over the Southern Ocean Using in Situ Observations Acquired During SOCRATES

   https://doi.org/10.1029/2020JD034482  

   D'Alessandro, John J.; McFarquhar, Greg M.; Wu, Wei; Stith, Jeff L.; Jensen, Jorgen B.; Rauber, Robert M. (June 2021, Journal of Geophysical Research: Atmospheres)

   Abstract Supercooled liquid water (SLW) and mixed phase clouds containing SLW and ice over the Southern Ocean (SO) are poorly represented in global climate and numerical weather prediction models. Observed SLW exists at lower temperatures than threshold values used to characterize its detrainment from convection in model parameterizations, and processes controlling its formation and removal are poorly understood. High‐resolution observations are needed to better characterize SLW over the SO. This study characterizes the frequency and spatial distribution of different cloud phases (liquid, ice, and mixed) using in situ observations acquired during the Southern Ocean Clouds, Radiation, Aerosol Transport Experiment Study. Cloud particle phase is identified using multiple cloud probes. Results show occurrence frequencies of liquid phase samples up to 70% between −20°C and 0°C and of ice phase samples up to 10% between −5°C and 0°C. Cloud phase spatial heterogeneity is determined by relating the total number of 1 s samples from a given cloud to the number of segments whose neighboring samples are the same phase. Mixed phase conditions are the most spatially heterogeneous from −20°C to 0°C, whereas liquid phase conditions from −10°C to 0°C and ice phase conditions from −20°C to −10°C are the least spatially heterogeneous. Greater spatial heterogeneity is associated with broader distributions of vertical velocity. Decreasing droplet concentrations and increasing number‐weighted mean liquid diameters occur within mixed phase clouds as the liquid water fraction decreases, possibly suggesting preferential evaporation of smaller drops during the Wegener‐Bergeron‐Findeisen process. 

   more » « less