Core-shell droplets and microcapsules formed through liquid-liquid phase separation of a colloid-polymer mixture.

Microcapsules allow for the controlled containment, transport, and release of cargoes ranging from pharmaceuticals to fragrances. Given the interest from a variety of industries in microcapsules and other core-shell structures, a multitude of fabrication strategies exist. Here, we report on a method relying on a mixture of temperature-responsive microgel particles, poly(N-isopropylacrylamide) (pNIPAM), and a polymer which undergo fluid-fluid phase separation. At room temperature this mixture separates into colloid-rich (liquid) and colloid-poor (gas) fluids. By heating the sample above a critical temperature where the microgel particles shrink dramatically and develop a more deeply attractive interparticle potential, the droplets of the colloid-rich phase become gel-like. As the temperature is lowered back to room temperature, these droplets of gelled colloidal particles reliquefy and phase separation within the droplet occurs. This phase separation leads to colloid-poor droplets within the colloid-rich droplets surrounded by a continuous colloid-poor phase. The gas/liquid/gas all-aqueous double emulsion lasts only a few minutes before a majority of the inner droplets escape. However, the colloid-rich shell of the core-shell droplets can solidify with the addition of salt. That this method creates core-shell structures with a shell composed of stimuli-sensitive microgel colloidal particles using only aqueous components makes it attractive for encapsulating biological materials and making capsules that respond to changes in, for example, temperature, salt concentration, or pH.

Using latent variable models to make gaming-the-system detection robust to context variations.

Gaming the system, a behavior in which learners exploit a system's properties to make progress while avoiding learning, has frequently been shown to be associated with lower learning. However, when we applied a previously validated gaming detector across conditions in experiments with an algebra tutor, the detected gaming was not associated with reduced learning, challenging its validity in our study context. Our exploratory data analysis suggested that varying contextual factors across and within conditions contributed to this lack of association. We present a new approach, latent variable-based gaming detection (LV-GD), that controls for contextual factors and more robustly estimates student-level latent gaming tendencies. In LV-GD, a student is estimated as having a high gaming tendency if the student is detected to game more than the expected level of the population given the context. LV-GD applies a statistical model on top of an existing action-level gaming detector developed based on a typical human labeling process, without additional labeling effort. Across three datasets, we find that LV-GD consistently outperformed the original detector in validity measured by association between gaming and learning as well as reliability. LV-GD also afforded high practical utility: it more accurately revealed intervention effects on gaming, revealed a correlation between gaming and perceived competence in math and helped understand productive detected gaming behaviors. Our approach is not only useful for others wanting a cost-effective way to adapt a gaming detector to their context but is also generally applicable in creating robust behavioral measures.

Crowding and confinement act in concert to slow DNA diffusion within cell-sized droplets.

Dynamics of biological macromolecules, such as DNA, in crowded and confined environments are critical to understanding cellular processes such as transcription, infection, and replication. However, the combined effects of cellular confinement and crowding on macromolecular dynamics remain poorly understood. Here, we use differential dynamic microscopy to investigate the diffusion of large DNA molecules confined in cell-sized droplets and crowded by dextran polymers. We show that confined and crowded DNA molecules exhibit universal anomalous subdiffusion with scaling that is insensitive to the degree of confinement and crowding. However, effective DNA diffusion coefficients D e f f decrease up to 2 orders of magnitude as droplet size decreases-an effect that is enhanced by increased crowding. We mathematically model the coupling of crowding and confinement by combining polymer scaling theories with confinement-induced depletion effects. The generality and tunability of our system and models render them applicable to elucidating wide-ranging crowded and confined systems.

Hydroxocobalamin interference in routine laboratory tests: Development of a protocol for identifying samples and reporting results from patients treated with CyanokitTM.

OBJECTIVES: Hydroxocobalamin (OHCob) is an antidote for cyanide poisoning in patients rescued from house fires and is known to cause interference with certain laboratory tests. Consensus is lacking on the extent of this interference and on how to handle these samples. The objectives of this study were to characterize OHCob interference across a wide range of laboratory tests and to develop protocols for identifying and reporting these samples. DESIGNS & METHODS: Patient plasma samples (n = 5) were spiked with OHCob (1.5 mg/mL) and compared to controls without this drug. A series of analytes were measured using chemistry, urinalysis, coagulation, hematology, and blood gas instruments. Dose-response testing was performed on a subset of assays that showed interferences ≥10%. RESULTS: Of the 77 analytes evaluated, 27 (35%) showed interference from OHCob, with chemistry and coagulation analytes showing the greatest effects. Of those affected, 22 analytes had a positive interference, whereas 5 analytes had negative interference. Dose-response studies showed dose-dependent increases and/or decreases consistent with initial spiking studies. Although red in colour, plasma samples with OHCob did not trigger hemolysis index flags, necessitating a special sample identification and reporting protocol. CONCLUSION: OHCob had significant effects on several analytes across different instruments. These findings led to the development of special sample handling and reporting protocols to identify OHCob samples and ensure only accurate results are released. It is vital for emergency departments to document and notify their laboratories whenever blood samples from these patients are drawn.