Liquid marbles as thermally robust droplets: coating-assisted Leidenfrost-like effect

The Leidenfrost effect-prolonged evaporation of droplets on a superheated surface-happens only when the surface temperature is above a certain transitional value. Here, we show that specially engineered droplets - liquid marbles - can exhibit similar effect at any superheated temperatures (up to 465 oC tested in our experiment) without a transition. Very possibly, this phenomenon is due to the fact that liquid marbles are droplets coated with microparticles and these microparticles help levitate the liquid core and maintain an insulation layer between the liquid and the superheated surface

Liquid marbles: topical context within soft matter and recent progress

The study of particle stabilized interfaces has a long history in terms of emulsions, foams and related dry powders. The same underlying interfacial energy principles also allow hydrophobic particles to encapsulate individual droplets into a stable form as individual macroscopic objects, which have recently been called "Liquid Marbles". Here we discuss conceptual similarities to superhydrophobic surfaces, capillary origami, slippery liquids-infused porous surfaces (SLIPS) and Leidenfrost droplets. We provide a review of recent progress on liquid marbles, since our earlier Emerging Area article (Soft Matter, 2011, 7, 5473–5481), and speculate on possible future directions from new liquid-infused liquid marbles to microarray applications. We highlight a range of properties of liquid marbles and describe applications including detecting changes in physical properties (e.g. pH, UV, NIR, temperature), use for gas sensing, synthesis of compounds/composites, blood typing and cell culture

480 Preliminary evaluation of a novel coronavirus vaccine (CORVax) using electroporation of plasmid DNA encoding a stabilized prefusion SARS-CoV-2 spike protein alone or with transfection of plasmid IL-12

Background SARS-CoV-2 (CoV2) has precipitated a global pandemic and the effectiveness of standard vaccine strategies to induce potent and persistent immunity to CoV2 is in question, particularly for the elderly. This problem is not dissimilar to what we have struggled with in our quest to induce immunity to cancer antigens, where vaccine-induced anti-cancer immune responses can be weak. Here, we describe a novel vaccine approach which leverages electroporation (EP) of a plasmid encoding a prefusion stabilized CoV2 spike protein (CORVax). As IL-12 has been shown to augment the efficacy of immunotherapy in aged mice,1 we have initiated studies to evaluate if plasmid IL-12 (TAVO™) can similarly augment anti-CoV2 immune responses in young mice and have planned studies in aged animals. Methods A prefusion stabilized CoV2 spike plasmid expression vector was constructed, a master cell bank generated and clinical-grade plasmid manufactured. C57BL/6 and BALB/c were vaccinated via intramuscular (IM) and/or intradermal (ID) injection followed immediately by EP of plasmids encoding the CoV2 spike protein with or without plasmid-encoded murine IL-12 on days 1 and 14 or 21. Mice were followed for \u3e120 days to assess safety. Splenocytes and serum were harvested at different time points to interrogate virus-specific cellular responses as well anti-spike IgG1/IgG2 antibody titers. A surrogate viral neutralization test (sVNT) assessed serum blockade of soluble hACE2R binding to immobilized CoV2 spike. Results Preliminary data shows that EP of CORVax alone or combined with IL-12 was safe. EP of CORVax was able to elicit anti-Spike IgG antibodies (IC50 = 1/2112), as well as IgG antibodies targeting the receptor binding domain of the Spike protein (IC50 = 1/965) approximately 40 days after the booster vaccination. In 2 of 2 experiments, CORVax combined with IL-12 significantly (P\u3c0.0001) increased the sVNT titers at 2 months, but this benefit was lost by 3 months. Conclusions Early preclinical data shows that EP of CORVax can induce IgG responses to CoV2 Spike and the receptor binding domain (RBD) as well as apparent viral neutralizing activity. The addition of IL-12, at least transiently, increased sVNT titer. We plan to investigate alternate vaccine boosting strategies while extending these studies into aged animals and initiate a clinical trial in the near future. References Ruby CE, Weinberg AD. OX40-Enhanced tumor rejection and effector T cell differentiation decreases with age. J Immunol2009;182:1481–9. https://doi.org/10.4049/jimmunol.182.3.1481. http://dx.doi.org/10.1136/jitc-2020-SITC2020.048

Comparison of vaporization models for feed droplet in fluid catalytic cracking risers

Vaporization of atomized feedstock is one of the critical processes in fluid catalytic cracking (FCC) risers; which is more often ignored in most of the FCC riser modelling studies. In this study, two different vaporization mechanisms of feedstock namely homogeneous mode and heterogeneous mode were studied. Different homogeneous models duly validated for various pure component droplets were applied to predict the vaporization time of the feed droplets typically expected in FCC feed vaporization zone. A new physical model for heterogeneous vaporization considering droplet-particle collision mechanics was also developed in the present study which compared well with the other existing heterogeneous modelling approaches. Comparison of the two vaporization modes indicates that under typical operating conditions of FCC riser, vaporization time of feed droplets predicted by heterogeneous mode is always lower than the homogeneous mode at least by an order of magnitude due to significant increase in heat transfer coefficient which accounts for droplet-particle contact. It is expected that actual vaporization time of feed droplets in an industrial FCC riser should lie in the range predicted by these two vaporization mechanisms which actually set the two limiting modes of vaporization. Obtained results predicted by the models could be used to aid design of the FCC feed vaporization zone