15 research outputs found
Comparisons of changes in the two-point discrimination test following muscle fatigue in healthy adults
High-bandwidth photomultiplication-type organic photodetectors with quantum dot interlayer
2
Nanoscale Soft Wetting Observed in Co/Sapphire during Pulsed Laser Irradiation
Liquid drops on deformable soft substrates exhibit quite complicated wetting behavior as compared to those on rigid solid substrates. We report on a soft wetting behavior of Co nanoparticles (NPs) on a sapphire substrate during pulsed laser-induced dewetting (PLID). Co NPs produced by PLID wetted the sapphire substrate with a contact angle near 70°, which is in contrast to typical dewetting behavior of metal thin films exhibiting contact angles greater than 90°. In addition, a nanoscale γ-Al2O3 wetting ridge about 15 nm in size and a thin amorphous Al2O3 interlayer were observed around and beneath the Co NP, respectively. The observed soft wetting behavior strongly indicates that the sapphire substrate became soft and deformable during PLID. Moreover, the soft wetting was augmented under PLID in air due to the formation of a CoO shell, resulting in a smaller contact angle near 30°
Nanoscale Soft Wetting Observed in Co/Sapphire during Pulsed Laser Irradiation
Liquid drops on deformable soft substrates exhibit quite complicated wetting behavior as compared to those on rigid solid substrates. We report on a soft wetting behavior of Co nanoparticles (NPs) on a sapphire substrate during pulsed laser-induced dewetting (PLID). Co NPs produced by PLID wetted the sapphire substrate with a contact angle near 70Ā°, which is in contrast to typical dewetting behavior of metal thin films exhibiting contact angles greater than 90Ā°. In addition, a nanoscale Ī³-Al2O3 wetting ridge about 15 nm in size and a thin amorphous Al2O3 interlayer were observed around and beneath the Co NP, respectively. The observed soft wetting behavior strongly indicates that the sapphire substrate became soft and deformable during PLID. Moreover, the soft wetting was augmented under PLID in air due to the formation of a CoO shell, resulting in a smaller contact angle near 30Ā°
Determination of twisting angle of electrospun nanofiber bundle for continuous electrospinning system
Electrospinning continuously produced twisted nanofibers with a convergence coil and a rotating ring collector. The positively charged nozzle was used in the electrospinning process to deposit electrospun fibers of polyacrylonitrile onto a rotating ring collector. By withdrawing the electrospun fibers from the rotating ring collector, it was possible to spin the electrospun fibers yarn. In this study, theoretical approaches and numerical simulations were used to determine the twisting angle of the yarn. Using the equations developed in this study, we performed numerical simulations and compared the experimental results with the numerical simulation results. Mechanical properties of the fiber bundle were analyzed for twisting angle. It was confirmed the relationship among the winding drum, the ring collector, and flux of the fibers mass per time during electrospinning in the developed system. (c) 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 4552
LightāMatter Interactions in Cesium Lead Halide Perovskite Nanowire Lasers
Lightāmatter
interactions in inorganic perovskite nanolasers
are investigated using single-crystalline cesium lead halide (CsPbX<sub>3</sub>, X = Cl, Br, and I) nanowires synthesized by the chemical
vapor transport method. The perovskite nanowires exhibit a uniform
growth direction, smooth surfaces, straight end facets, and homogeneous
composition distributions. Lasing occurs in the perovskite nanowires
at low thresholds (3 Ī¼J/cm<sup>2</sup>) with high quality factors
(<i>Q</i> = 1200ā1400) under ambient atmospheric
environments. The wavelengths of the nanowire lasers are tunable by
controlling the stoichiometry of the halide, allowing the lasing of
the inorganic perovskite nanowires from blue to red. The unusual spacing
of the FabryāPeĢrot modes suggests strong lightāmatter
interactions in the reduced mode volume of the nanowires, while the
polarization of the lasing indicates that the FabryāPeĢrot
modes belong to the same fundamental transverse mode. The dispersion
curve of the excitonāpolariton model suggests that the group
refractive index of the polariton is significantly enhanced
Band-Gap States of AgIn<sub>5</sub>S<sub>8</sub> and ZnSāAgIn<sub>5</sub>S<sub>8</sub> Nanoparticles
The size-dependent band-gap energies
of AgIn<sub>5</sub>S<sub>8</sub> nanoparticles were directly measured
for the first time using absorption
and photoluminescence spectroscopies, which enabled an explanation
of the evolution of the band-gap energy with the quantum-confinement
effect in AgIn<sub>5</sub>S<sub>8</sub> nanoparticles. The band-gap
transition in steady-state and time-resolved photoluminescence spectra
indicated that the stable structure of the AgIn<sub>5</sub>S<sub>8</sub> nanoparticles was the cubic phase. The electronic band structures
of the AgāInāS nanoparticles were mainly related to
the crystal structures, although the stoichiometry affected the band
energies to some extent. Zn doping led to the formation of a ZnSāAgIn<sub>5</sub>S<sub>8</sub> solid solution, as supported by the significant
changes in the electronic band structures of the AgIn<sub>5</sub>S<sub>8</sub> nanoparticles. Controlling the size and stoichiometry allowed
the emission of the AgāInāS nanoparticles to be tuned
in the entire visible regime
Enhancement Mechanism of the Photoluminescence Quantum Yield in Highly Efficient ZnSāAgIn<sub>5</sub>S<sub>8</sub> Quantum Dots with Core/Shell Structures
The
optical properties of ZnSāAgIn<sub>5</sub>S<sub>8</sub> quantum
dots (QDs) with core/shell structures are examined to clarify
the enhancement mechanism of the photoluminescence (PL) quantum yield
(QY). Two types of QDs are synthesized by varying the concentration
of zinc precursors, with alloyed-core (ZnSāAgIn<sub>5</sub>S<sub>8</sub>, ZAIS), inner-shell (ZnIn<sub>2</sub>S<sub>4</sub>,
ZIS), and outer-shell (ZnS) structures, such as ZAIS/ZIS/ZnS and ZAIS/ZnS.
Upon alloying/shelling processes from the preformed AgIn<sub>5</sub>S<sub>8</sub> QDs, the evolution of the band gap energy indicates
the formation of the solid solution of ZAIS. Due to the difference
in the degree of alloying between ZAIS/ZIS/ZnS and ZAIS/ZnS QDs, the
blue shift of PL, Stokes shift, and QY are different. The alloying/shelling
processes improve the QY of the intrinsic defect states more effectively
than the QY of the surface defect states, while the time-resolved
studies suggest that the enhanced radiative rate of the intrinsic
states is responsible for the improvement of the QY, in addition to
the reduced nonradiative rate. In ZAIS/ZIS/ZnS QDs, the QY increases
to 85%, which is attributed to the existence of the ZIS layer, as
well as the reduced nonradiative states and the enhanced radiative
states by the alloying/shelling processes. The ZIS layer mitigates
the lattice strains and provides the appropriate levels of the electronic
structures in the QDs, which further reduces the nonradiative rate
and enhances the radiative rate, respectively, leading to the unprecedentedly
high PL QY of ZAIS/ZIS/ZnS QDs