15 research outputs found
Janus Polymer Single Crystal Nanosheet via Evaporative Crystallization
We
show that liquid/liquid interface can guide polymer chain folding
during crystallization. Evaporation-induced crystallization of telechelic
dicarboxyl end-functionalized polyÂ(ε-caprolactone) (COOH-PCL-COOH)
at a water/pentyl acetate interface produced millimeter-scale, uniform
polymer single crystal (PSC) films. Due to the asymmetric nature at
the interface, the PSC nanosheets exhibited a Janus structure: the
two surfaces of the crystal showed distinct water contact angle, which
are quantitatively confirmed by in situ nanocondensation using environmental
scanning electron microscopy (ESEM)
Deep Color-Corrected Multi-scale Retinex Network for Underwater Image Enhancement
The acquisition of high-quality underwater images is of great importance to ocean exploration activities. However, images captured in the underwater environment often suffer from degradation due to complex imaging conditions, leading to various issues, such as color cast, low contrast and low visibility. Although many traditional methods have been used to address these issues, they usually lack robustness in diverse underwater scenes. On the other hand, deep learning techniques struggle to generalize to unseen images, due to the challenge of learning the complicated degradation process. Inspired by the success achieved by the Retinex-based methods, we decompose the Underwater Image Enhancement (UIE) task into two consecutive procedures, including color correction and visibility enhancement, and introduce a novel deep Color-Corrected Multi-scale Retinex Network (CCMSR-Net). With regard to the two procedures, this network comprises a Color Correction subnetwork (CC-Net) and a Multi-scale Retinex subnetwork (MSR-Net), which are built on top of the Hybrid Convolution-Axial Attention Block (HCAAB) that we design. Thanks to this block, the CCMSR-Net is able to efficiently capture local characteristics and the global context. Experimental results show that the CCMSR-Net outperforms, or at least performs comparably to, 11 baselines across five test sets. We believe that these promising results are due to the effective combination of color correction methods and the multi-scale Retinex model, achieved by jointly exploiting Convolutional Neural Networks (CNNs) and Transformers.</p
In Situ Real-Time Study on Dynamics of Microbially Induced Calcium Carbonate Precipitation at a Single-Cell Level
Ureolytic
microbially induced calcium carbonate precipitation (MICP) is a promising
green technique for addressing a variety of environmental and architectural
concerns. However, the dynamics of MICP especially at the microscopic
level remains relatively unexplored. In this work, by applying a bacterial
tracking technique, the growth dynamics of micrometer-sized calcium
carbonate precipitates induced by <i>Sporosarcina pasteurii</i> were studied at a single-cell resolution. The growth of micrometer-scale
precipitates and the occurrence and dissolution of many unstable submicrometer
calcium carbonate particles were observed in the precipitation process.
More interestingly, we observed that micrometer-sized precipitated
crystals did not grow on negatively charged cell surfaces nor on other
tested polystyrene microspheres with different negatively charged
surface modifications, indicating that a negatively charged surface
was not a sufficient property for nucleating the growth of precipitates
in the MICP process under the conditions used in this study. Our observations
imply that the frequently cited model of bacterial cell surfaces as
nucleation sites for precipitates during MICP is oversimplified. In
addition, additional growth of calcium carbonates was observed on
old precipitates collected from previous runs. The presence of bacterial
cells was also shown to affect both morphologies and crystalline structures
of precipitates, and both calcite and vaterite precipitates were found
when cells physically coexisted with precipitates. This study provides
new insights into the regulation of MICP through dynamic control of
precipitation
In Situ Real-Time Study on Dynamics of Microbially Induced Calcium Carbonate Precipitation at a Single-Cell Level
Ureolytic
microbially induced calcium carbonate precipitation (MICP) is a promising
green technique for addressing a variety of environmental and architectural
concerns. However, the dynamics of MICP especially at the microscopic
level remains relatively unexplored. In this work, by applying a bacterial
tracking technique, the growth dynamics of micrometer-sized calcium
carbonate precipitates induced by <i>Sporosarcina pasteurii</i> were studied at a single-cell resolution. The growth of micrometer-scale
precipitates and the occurrence and dissolution of many unstable submicrometer
calcium carbonate particles were observed in the precipitation process.
More interestingly, we observed that micrometer-sized precipitated
crystals did not grow on negatively charged cell surfaces nor on other
tested polystyrene microspheres with different negatively charged
surface modifications, indicating that a negatively charged surface
was not a sufficient property for nucleating the growth of precipitates
in the MICP process under the conditions used in this study. Our observations
imply that the frequently cited model of bacterial cell surfaces as
nucleation sites for precipitates during MICP is oversimplified. In
addition, additional growth of calcium carbonates was observed on
old precipitates collected from previous runs. The presence of bacterial
cells was also shown to affect both morphologies and crystalline structures
of precipitates, and both calcite and vaterite precipitates were found
when cells physically coexisted with precipitates. This study provides
new insights into the regulation of MICP through dynamic control of
precipitation
In Situ Real-Time Study on Dynamics of Microbially Induced Calcium Carbonate Precipitation at a Single-Cell Level
Ureolytic
microbially induced calcium carbonate precipitation (MICP) is a promising
green technique for addressing a variety of environmental and architectural
concerns. However, the dynamics of MICP especially at the microscopic
level remains relatively unexplored. In this work, by applying a bacterial
tracking technique, the growth dynamics of micrometer-sized calcium
carbonate precipitates induced by <i>Sporosarcina pasteurii</i> were studied at a single-cell resolution. The growth of micrometer-scale
precipitates and the occurrence and dissolution of many unstable submicrometer
calcium carbonate particles were observed in the precipitation process.
More interestingly, we observed that micrometer-sized precipitated
crystals did not grow on negatively charged cell surfaces nor on other
tested polystyrene microspheres with different negatively charged
surface modifications, indicating that a negatively charged surface
was not a sufficient property for nucleating the growth of precipitates
in the MICP process under the conditions used in this study. Our observations
imply that the frequently cited model of bacterial cell surfaces as
nucleation sites for precipitates during MICP is oversimplified. In
addition, additional growth of calcium carbonates was observed on
old precipitates collected from previous runs. The presence of bacterial
cells was also shown to affect both morphologies and crystalline structures
of precipitates, and both calcite and vaterite precipitates were found
when cells physically coexisted with precipitates. This study provides
new insights into the regulation of MICP through dynamic control of
precipitation
In Situ Real-Time Study on Dynamics of Microbially Induced Calcium Carbonate Precipitation at a Single-Cell Level
Ureolytic
microbially induced calcium carbonate precipitation (MICP) is a promising
green technique for addressing a variety of environmental and architectural
concerns. However, the dynamics of MICP especially at the microscopic
level remains relatively unexplored. In this work, by applying a bacterial
tracking technique, the growth dynamics of micrometer-sized calcium
carbonate precipitates induced by <i>Sporosarcina pasteurii</i> were studied at a single-cell resolution. The growth of micrometer-scale
precipitates and the occurrence and dissolution of many unstable submicrometer
calcium carbonate particles were observed in the precipitation process.
More interestingly, we observed that micrometer-sized precipitated
crystals did not grow on negatively charged cell surfaces nor on other
tested polystyrene microspheres with different negatively charged
surface modifications, indicating that a negatively charged surface
was not a sufficient property for nucleating the growth of precipitates
in the MICP process under the conditions used in this study. Our observations
imply that the frequently cited model of bacterial cell surfaces as
nucleation sites for precipitates during MICP is oversimplified. In
addition, additional growth of calcium carbonates was observed on
old precipitates collected from previous runs. The presence of bacterial
cells was also shown to affect both morphologies and crystalline structures
of precipitates, and both calcite and vaterite precipitates were found
when cells physically coexisted with precipitates. This study provides
new insights into the regulation of MICP through dynamic control of
precipitation
In Situ Real-Time Study on Dynamics of Microbially Induced Calcium Carbonate Precipitation at a Single-Cell Level
Ureolytic
microbially induced calcium carbonate precipitation (MICP) is a promising
green technique for addressing a variety of environmental and architectural
concerns. However, the dynamics of MICP especially at the microscopic
level remains relatively unexplored. In this work, by applying a bacterial
tracking technique, the growth dynamics of micrometer-sized calcium
carbonate precipitates induced by <i>Sporosarcina pasteurii</i> were studied at a single-cell resolution. The growth of micrometer-scale
precipitates and the occurrence and dissolution of many unstable submicrometer
calcium carbonate particles were observed in the precipitation process.
More interestingly, we observed that micrometer-sized precipitated
crystals did not grow on negatively charged cell surfaces nor on other
tested polystyrene microspheres with different negatively charged
surface modifications, indicating that a negatively charged surface
was not a sufficient property for nucleating the growth of precipitates
in the MICP process under the conditions used in this study. Our observations
imply that the frequently cited model of bacterial cell surfaces as
nucleation sites for precipitates during MICP is oversimplified. In
addition, additional growth of calcium carbonates was observed on
old precipitates collected from previous runs. The presence of bacterial
cells was also shown to affect both morphologies and crystalline structures
of precipitates, and both calcite and vaterite precipitates were found
when cells physically coexisted with precipitates. This study provides
new insights into the regulation of MICP through dynamic control of
precipitation
In Situ Real-Time Study on Dynamics of Microbially Induced Calcium Carbonate Precipitation at a Single-Cell Level
Ureolytic
microbially induced calcium carbonate precipitation (MICP) is a promising
green technique for addressing a variety of environmental and architectural
concerns. However, the dynamics of MICP especially at the microscopic
level remains relatively unexplored. In this work, by applying a bacterial
tracking technique, the growth dynamics of micrometer-sized calcium
carbonate precipitates induced by <i>Sporosarcina pasteurii</i> were studied at a single-cell resolution. The growth of micrometer-scale
precipitates and the occurrence and dissolution of many unstable submicrometer
calcium carbonate particles were observed in the precipitation process.
More interestingly, we observed that micrometer-sized precipitated
crystals did not grow on negatively charged cell surfaces nor on other
tested polystyrene microspheres with different negatively charged
surface modifications, indicating that a negatively charged surface
was not a sufficient property for nucleating the growth of precipitates
in the MICP process under the conditions used in this study. Our observations
imply that the frequently cited model of bacterial cell surfaces as
nucleation sites for precipitates during MICP is oversimplified. In
addition, additional growth of calcium carbonates was observed on
old precipitates collected from previous runs. The presence of bacterial
cells was also shown to affect both morphologies and crystalline structures
of precipitates, and both calcite and vaterite precipitates were found
when cells physically coexisted with precipitates. This study provides
new insights into the regulation of MICP through dynamic control of
precipitation
Responsive Shape Change of Sub‑5 nm Thin, Janus Polymer Nanoplates
Responsive shape changes in soft
materials have attracted significant
attention in recent years. Despite extensive studies, it is still
challenging to prepare nanoscale assemblies with responsive behaviors.
Herein we report on the fabrication and pH-responsive properties of
sub-5 nm thin, Janus polymer nanoplates prepared via crystallization-driven
self-assembly of polyÂ(ε-caprolactone)-<i>b</i>-polyÂ(acrylic
acid) (PCL-<i>b</i>-PAA) followed by cross-linking and disassembly.
The resultant Janus nanoplate is comprised of partially cross-linked
PAA and tethered PCL brush layers with an overall thickness of ∼4
nm. We show that pronounced and reversible shape changes from nanoplates
to nanobowls can be realized in such a thin free-standing film. This
shape change is achieved by exceptionally small stressî—¸a few
orders of magnitude smaller than conventional hydrogel bilayers. These
three-dimensional ultrathin nanobowls are also mechanically stable,
which is attributed to the tortoise-shell-like crystalline domains
formed in the nanoconfined curved space. Our results pave a way to
a new class of free-standing, ultrathin polymer Janus nanoplates that
may find applications in nanomotors and nanoactuators
Structure and Morphology of Poly(vinylidene fluoride) Nanoscrolls
To date the scrolled morphology of
γ-phase polyÂ(vinylidene
fluoride) (PVDF) has been witnessed via high temperature melt crystallization
of crystalline thin films and through imaging of chemical etched PVDF
bulk films. Here we show the first growth and characterization of
free-standing γ-phase PVDF scrolls via solution crystallization.
Scanning electron microscopy, transmission electron microscopy, and
atomic force microscopy have been used to characterize and to further
understand the fundamental preferred crystalline habit of the γ-phase
of PVDF