185 research outputs found
Converting Vertical Vibration of Anisotropic Ratchet Conveyors into Horizontal Droplet Motion
An anisotropic ratchet
conveyor is an asymmetric, periodic, micropatterned
surface that propels droplets when vibrated with a sinusoidal signal
at certain frequencies and amplitudes. For each input frequency, there
is a threshold amplitude beyond which the droplet starts to move.
In this paper, we study the parameters that initiate droplet motion
and the relationship between the input frequency and threshold amplitude
among droplets with different volume, density, viscosity, and surface
tension. Through this investigation we demonstrate how nondimensionalization
reveals consistent behavior for droplets of different volumes. Finally,
we propose a compact model that captures the essential features of
the system to describe how a pure vertical vibration results in horizontal
droplet motion. This model provides an intuitive understanding of
the underlying physics and explains how the surface asymmetry is the
key for lateral droplet motion
Converting Vertical Vibration of Anisotropic Ratchet Conveyors into Horizontal Droplet Motion
An anisotropic ratchet
conveyor is an asymmetric, periodic, micropatterned
surface that propels droplets when vibrated with a sinusoidal signal
at certain frequencies and amplitudes. For each input frequency, there
is a threshold amplitude beyond which the droplet starts to move.
In this paper, we study the parameters that initiate droplet motion
and the relationship between the input frequency and threshold amplitude
among droplets with different volume, density, viscosity, and surface
tension. Through this investigation we demonstrate how nondimensionalization
reveals consistent behavior for droplets of different volumes. Finally,
we propose a compact model that captures the essential features of
the system to describe how a pure vertical vibration results in horizontal
droplet motion. This model provides an intuitive understanding of
the underlying physics and explains how the surface asymmetry is the
key for lateral droplet motion
Anomalous Temperature-Dependent Upconversion Luminescence of Small-Sized NaYF<sub>4</sub>:Yb<sup>3+</sup>, Er<sup>3+</sup> Nanoparticles
Size-dependent
quantum confinement has important effects on the
energy transfer and radiative and nonradiative transitions in nanophosphors.
For lanthanide-doped nanoparticles, the confinement effect is induced
mostly via electronâphonon interaction, and analysis of temperature-dependent
spectroscopic properties provides an effective method for disclosing
its underlying mechanism. Herein, an intriguing and unprecedented
enhancement of the upconversion luminescence (UCL) at higher temperatures
in hexagonal-phase NaYF<sub>4</sub>:Yb<sup>3+</sup>, Er<sup>3+</sup> upconversion nanoparticles (UCNPs) is reported. Moreover, this anomalous
UCL enhancement shows a strong dependence on the particle size and
becomes more significant for UCNPs with a smaller size. This anomalous
thermal behavior is interpreted on the basis of phonon-assisted energy
transfer and phonon confinement effect. The findings are relevant
to the engineering of the nanostructures of UCNPs and to the further
understanding of the UCL mechanism
A Wireless, Regeneratable Cocaine Sensing Scheme Enabled by Allosteric Regulation of pH Sensitive Aptamers
A key challenge for achieving continuous biosensing with
existing
technologies is the poor reusability of the biorecognition interface
due to the difficulty in the dissociation of analytes from the bioreceptors
upon surface saturation. In this work, we introduce a regeneratable
biosensing scheme enabled by allosteric regulation of a re-engineered
pH sensitive anti-cocaine aptamer. The aptamer can regain its affinity
with target analytes due to proton-promoted duplex-to-triplex transition
in DNA configuration followed by the release of adsorbed analytes.
A Pd/PdHx electrode placed next to the
sensor can enable the pH regulation of the local chemical environment
via electrochemical reactions. Demonstration of a âflower-shapedâ,
stretchable, and inductively coupled electronic system with sensing
and energy harvesting capabilities provides a promising route to designing
wireless devices in biointegrated forms. These advances have the potential
for future development of electronic sensing platforms with on-chip
regeneration capability for continuous, quantitative, and real-time
monitoring of chemical and biological markers
A Wireless, Regeneratable Cocaine Sensing Scheme Enabled by Allosteric Regulation of pH Sensitive Aptamers
A key challenge for achieving continuous biosensing with
existing
technologies is the poor reusability of the biorecognition interface
due to the difficulty in the dissociation of analytes from the bioreceptors
upon surface saturation. In this work, we introduce a regeneratable
biosensing scheme enabled by allosteric regulation of a re-engineered
pH sensitive anti-cocaine aptamer. The aptamer can regain its affinity
with target analytes due to proton-promoted duplex-to-triplex transition
in DNA configuration followed by the release of adsorbed analytes.
A Pd/PdHx electrode placed next to the
sensor can enable the pH regulation of the local chemical environment
via electrochemical reactions. Demonstration of a âflower-shapedâ,
stretchable, and inductively coupled electronic system with sensing
and energy harvesting capabilities provides a promising route to designing
wireless devices in biointegrated forms. These advances have the potential
for future development of electronic sensing platforms with on-chip
regeneration capability for continuous, quantitative, and real-time
monitoring of chemical and biological markers
[Bmim]PF<sub>6</sub>âPromoted Ligandless SuzukiâMiyaura Coupling Reaction of Potassium Aryltrifluoroborates in Water
The
SuzukiâMiyaura coupling reactions of potassium aryltrifluoroborates
with aryl bromides in water are promoted by the addition of [bmim]ÂPF<sub>6</sub> using PdÂ(OAc)<sub>2</sub> as a catalyst and Na<sub>2</sub>CO<sub>3</sub> as a base under air. The quantity of [bmim]ÂPF<sub>6</sub> used is crucial to the efficiency of the catalytic system.
A wide range of biaryls and polyaryls can be easily prepared in good
to excellent yields
Supplementary document for Printable and Low-cost Perfect Terahertz Absorber Realized by Laser-induced Graphene Metasurface - 6579509.pdf
Comparisons between this work and relevant researc
Distribution of the decay time in (A) PACAP and (B) L-DOPA treated PC12 cells.
<p>Histograms indicate the existence of two populations of spikes that can be well fitted with two Gaussian functions. PACAP reduces the proportion of rapid spikes of the decay time. Moreover, PACAP shortens the decay time of both fast and slow spikes. In contrast, distributions of decay time of both fast and slow spikes are shifted to the right by the treatment of L-DOPA.</p
Representative amperometric foot current transients (A) and summary of foot duration, foot quantal size and mean catecholamine flux (B).
<p>Flux was computed as foot area divided by duration. Error bars represent mean ± SEM (control, 93 events; PACAP, 146 events and L-DOPA, 52 events). *** p<0.001 and ** p<0.01 vs. control, respectively (ANOVA test).</p
Representative TEM images of (A) control and (B) PACAP-treated cells.
<p>Large dense core vesicles are distributed near and far from the plasma membranes. A portion of the nucleus can be seen in the cells. Scale barsâ=â200 nm. (C) Mean vesicle sizes of control and PACAP-treated cells (nâ=â17 cells from control group, nâ=â24 cells for PACAP-treated group; **<i>p</i><0.01 vs. control cells, <i>t-</i>test).</p
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