6 research outputs found
On explosive boiling of a multicomponent Leidenfrost drop
The gasification of multicomponent fuel drops is relevant in various
energy-related technologies. An interesting phenomenon associated with this
process is the self-induced explosion of the drop, producing a multitude of
smaller secondary droplets, which promotes overall fuel atomization and,
consequently, improves the combustion efficiency and reduces emissions of
liquid-fueled engines. Here, we study a unique explosive gasification process
of a tricomponent droplet consisting of water, ethanol, and oil ("ouzo"), by
high-speed monitoring of the entire gasification event taking place in the
well-controlled, levitated Leidenfrost state over a superheated plate. It is
observed that the preferential evaporation of the most volatile component,
ethanol, triggers nucleation of the oil microdroplets/nanodroplets in the
remaining drop, which, consequently, becomes an opaque oil-in-water
microemulsion. The tiny oil droplets subsequently coalesce into a large one,
which, in turn, wraps around the remnant water. Because of the encapsulating
oil layer, the droplet can no longer produce enough vapor for its levitation,
and, thus, falls and contacts the superheated surface. The direct thermal
contact leads to vapor bubble formation inside the drop and consequently drop
explosion in the final stage.Comment: 8 pages, 5 figure
Universal thermal response of the multiscale nanodomains formed in trans-anethol/ethanol/water surfactant-free microemulsion
Hypothesis: Surfactant-free microemulsion (SFME), an emerging phenomenology
that occurs in the monophasic zone of a broad category of ternary mixtures
'hydrophobe/hydrotrope/water', has attracted extensive interests due to their
unique physicochemical properties. The potential of this kind of ternary fluid
for solubilization and drug delivery make them promising candidates in many
industrial scenarios. Experiments: Here the thermodynamic behavior of these
multiscale nanodomains formed in the ternary trans-anethol/ethanol/water system
over a wide range of temperatures is explored. The macroscopic physical
properties of the ternary solutions are characterized, with revealing the
temperature dependence of refractive index and dynamic viscosity. Findings:
With increasing temperature, the ternary system shows extended areas in the
monophasic zone. We demonstrate that the phase behavior and the multiscale
nanodomains formed in the monophasic zone can be precisely and reversibly tuned
by altering the temperature. Increasing temperature can destroy the stability
of the multiscale nanodomains in equilibrium, with an exponential decay in the
scattering light intensity. Nevertheless, molecular-scale aggregates and
mesoscopic droplets exhibit significantly different response behaviors to
temperature stimuli. The temperature-sensitive nature of the ternary SFME
system provides a crucial step forward exploring and industrializing its
stability
Cytoplasmic Lipid Droplets Are Sites of Convergence of Proteasomal and Autophagic Degradation of Apolipoprotein B
Lipid esters stored in cytoplasmic lipid droplets (CLDs) of hepatocytes are used to synthesize very low-density lipoproteins (VLDLs), into which apolipoprotein B (ApoB) is integrated cotranslationally. In the present study, by using Huh7 cells, derived from human hepatoma and competent for VLDL secretion, we found that ApoB is highly concentrated around CLDs to make “ApoB-crescents.” ApoB-crescents were seen in <10% of Huh7 cells under normal conditions, but the ratio increased to nearly 50% after 12 h of proteasomal inhibition by N-acetyl-l-leucinyl-l-leucinyl-l-norleucinal. Electron microscopy showed ApoB to be localized to a cluster of electron-lucent particles 50–100 nm in diameter adhering to CLDs. ApoB, proteasome subunits, and ubiquitinated proteins were detected in the CLD fraction, and this ApoB was ubiquitinated. Interestingly, proteasome inhibition also caused increases in autophagic vacuoles and ApoB in lysosomes. ApoB-crescents began to decrease after 12–24 h of proteasomal inhibition, but the decrease was blocked by an autophagy inhibitor, 3-methyladenine. Inhibition of autophagy alone caused an increase in ApoB-crescents. These observations indicate that both proteasomal and autophagy/lysosomal degradation of ApoB occur around CLDs and that the CLD surface functions as a unique platform for convergence of the two pathways