12 research outputs found
Realization of a three-dimensional photonic topological insulator
Confining photons in a finite volume is in high demand in modern photonic
devices. This motivated decades ago the invention of photonic crystals,
featured with a photonic bandgap forbidding light propagation in all
directions. Recently, inspired by the discoveries of topological insulators
(TIs), the confinement of photons with topological protection has been
demonstrated in two-dimensional (2D) photonic structures known as photonic TIs,
with promising applications in topological lasers and robust optical delay
lines. However, a fully three-dimensional (3D) topological photonic bandgap has
never before been achieved. Here, we experimentally demonstrate a 3D photonic
TI with an extremely wide (> 25% bandwidth) 3D topological bandgap. The sample
consists of split-ring resonators (SRRs) with strong magneto-electric coupling
and behaves as a 'weak TI', or a stack of 2D quantum spin Hall insulators.
Using direct field measurements, we map out both the gapped bulk bandstructure
and the Dirac-like dispersion of the photonic surface states, and demonstrate
robust photonic propagation along a non-planar surface. Our work extends the
family of 3D TIs from fermions to bosons and paves the way for applications in
topological photonic cavities, circuits, and lasers in 3D geometries
Advanced deep learning models for phenotypic trait extraction and cultivar classification in lychee using photon-counting micro-CT imaging
IntroductionIn contemporary agronomic research, the focus has increasingly shifted towards non-destructive imaging and precise phenotypic characterization. A photon-counting micro-CT system has been developed, which is capable of imaging lychee fruit at the micrometer level and capturing a full energy spectrum, thanks to its advanced photon-counting detectors.MethodsFor automatic measurement of phenotypic traits, seven CNN-based deep learning models including AttentionUNet, DeeplabV3+, SegNet, TransUNet, UNet, UNet++, and UNet3+ were developed. Machine learning techniques tailored for small-sample training were employed to identify key characteristics of various lychee species.ResultsThese models demonstrate outstanding performance with Dice, Recall, and Precision indices predominantly ranging between 0.90 and 0.99. The Mean Intersection over Union (MIoU) consistently falls between 0.88 and 0.98. This approach served both as a feature selection process and a means of classification, significantly enhancing the study's ability to discern and categorize distinct lychee varieties.DiscussionThis research not only contributes to the advancement of non-destructive plant analysis but also opens new avenues for exploring the intricate phenotypic variations within plant species
Profiling and predicting the problem-solving patterns in China’s research systems: A methodology of intelligent bibliometrics and empirical insights
Uncovering the driving forces, strategic landscapes, and evolutionary mechanisms of China’s research systems is attracting rising interest around the globe. One such interest is to understand the problem-solving patterns in China’s research systems now and in the future. Targeting a set of high-quality research articles published by Chinese researchers between 2009 and 2018, and indexed in the Essential Science Indicators database, we developed an intelligent bibliometrics-based methodology for identifying the problem-solving patterns from scientific documents. Specifically, science overlay maps incorporating link prediction were used to profile China’s disciplinary interactions and predict potential cross-disciplinary innovation at a macro level. We proposed a function incorporating word embedding techniques to represent subjects, actions, and objects (SAO) retrieved from combined titles and abstracts into vectors and constructed a tri-layer SAO network to visualize SAOs and their semantic relationships. Then, at a micro level, we developed network analytics for identifying problems and solutions from the SAO network, and recommending potential solutions for existing problems. Empirical insights derived from this study provide clues to understand China’s research strengths and the science policies beneath them, along with the key research problems and solutions Chinese researchers are focusing on now and might pursue in the future.</p
Vibration Analysis of Corn Header Silage Module Rack Based on Technological System Evolution
Isotope Effect-Enabled Crystal Enlargement in Metal–Organic Frameworks
Synthesizing large metal–organic framework (MOF)
single
crystals has garnered significant research interest, although it is
hindered by the fast nucleation kinetics that gives rise to numerous
small nuclei. Given the different chemical origins inherent in various
types of MOFs, the development of a general approach to enhancing
their crystal sizes presents a formidable challenge. Here, we propose
a simple isotopic substitution strategy to promote size growth in
MOFs by inhibiting nucleation, resulting in a substantial increase
in the crystal volume ranging from 1.7- to 165-fold. Impressively,
the crystals prepared under optimized conditions by normal approaches
can be further enlarged by the isotope effect, yielding the largest
MOF single crystal (2.9 cm × 0.48 cm × 0.23 cm) among the
one-pot synthesis method. Detailed in situ characterizations
reveal that the isotope effect can retard crystallization kinetics,
establish a higher nucleation energy barrier, and consequently generate
fewer nuclei that eventually grow larger. Compared with the smaller
crystals, the isotope effect-enlarged crystal shows 33% improvement
in the X-ray dose rate detection limit. This work enriches the understanding
of the isotope effect on regulating the crystallization process and
provides inspiration for exploring potential applications of large
MOF single crystals
Isotope Effect-Enabled Crystal Enlargement in Metal–Organic Frameworks
Synthesizing large metal–organic framework (MOF)
single
crystals has garnered significant research interest, although it is
hindered by the fast nucleation kinetics that gives rise to numerous
small nuclei. Given the different chemical origins inherent in various
types of MOFs, the development of a general approach to enhancing
their crystal sizes presents a formidable challenge. Here, we propose
a simple isotopic substitution strategy to promote size growth in
MOFs by inhibiting nucleation, resulting in a substantial increase
in the crystal volume ranging from 1.7- to 165-fold. Impressively,
the crystals prepared under optimized conditions by normal approaches
can be further enlarged by the isotope effect, yielding the largest
MOF single crystal (2.9 cm × 0.48 cm × 0.23 cm) among the
one-pot synthesis method. Detailed in situ characterizations
reveal that the isotope effect can retard crystallization kinetics,
establish a higher nucleation energy barrier, and consequently generate
fewer nuclei that eventually grow larger. Compared with the smaller
crystals, the isotope effect-enlarged crystal shows 33% improvement
in the X-ray dose rate detection limit. This work enriches the understanding
of the isotope effect on regulating the crystallization process and
provides inspiration for exploring potential applications of large
MOF single crystals
A novel electrochemical sensor based on TiO2–Ti3C2TX/CTAB/chitosan composite for the detection of nitrite
Isotope Effect-Enabled Crystal Enlargement in Metal–Organic Frameworks
Synthesizing large metal–organic framework (MOF)
single
crystals has garnered significant research interest, although it is
hindered by the fast nucleation kinetics that gives rise to numerous
small nuclei. Given the different chemical origins inherent in various
types of MOFs, the development of a general approach to enhancing
their crystal sizes presents a formidable challenge. Here, we propose
a simple isotopic substitution strategy to promote size growth in
MOFs by inhibiting nucleation, resulting in a substantial increase
in the crystal volume ranging from 1.7- to 165-fold. Impressively,
the crystals prepared under optimized conditions by normal approaches
can be further enlarged by the isotope effect, yielding the largest
MOF single crystal (2.9 cm × 0.48 cm × 0.23 cm) among the
one-pot synthesis method. Detailed in situ characterizations
reveal that the isotope effect can retard crystallization kinetics,
establish a higher nucleation energy barrier, and consequently generate
fewer nuclei that eventually grow larger. Compared with the smaller
crystals, the isotope effect-enlarged crystal shows 33% improvement
in the X-ray dose rate detection limit. This work enriches the understanding
of the isotope effect on regulating the crystallization process and
provides inspiration for exploring potential applications of large
MOF single crystals
Isotope Effect-Enabled Crystal Enlargement in Metal–Organic Frameworks
Synthesizing large metal–organic framework (MOF)
single
crystals has garnered significant research interest, although it is
hindered by the fast nucleation kinetics that gives rise to numerous
small nuclei. Given the different chemical origins inherent in various
types of MOFs, the development of a general approach to enhancing
their crystal sizes presents a formidable challenge. Here, we propose
a simple isotopic substitution strategy to promote size growth in
MOFs by inhibiting nucleation, resulting in a substantial increase
in the crystal volume ranging from 1.7- to 165-fold. Impressively,
the crystals prepared under optimized conditions by normal approaches
can be further enlarged by the isotope effect, yielding the largest
MOF single crystal (2.9 cm × 0.48 cm × 0.23 cm) among the
one-pot synthesis method. Detailed in situ characterizations
reveal that the isotope effect can retard crystallization kinetics,
establish a higher nucleation energy barrier, and consequently generate
fewer nuclei that eventually grow larger. Compared with the smaller
crystals, the isotope effect-enlarged crystal shows 33% improvement
in the X-ray dose rate detection limit. This work enriches the understanding
of the isotope effect on regulating the crystallization process and
provides inspiration for exploring potential applications of large
MOF single crystals
Isotope Effect-Enabled Crystal Enlargement in Metal–Organic Frameworks
Synthesizing large metal–organic framework (MOF)
single
crystals has garnered significant research interest, although it is
hindered by the fast nucleation kinetics that gives rise to numerous
small nuclei. Given the different chemical origins inherent in various
types of MOFs, the development of a general approach to enhancing
their crystal sizes presents a formidable challenge. Here, we propose
a simple isotopic substitution strategy to promote size growth in
MOFs by inhibiting nucleation, resulting in a substantial increase
in the crystal volume ranging from 1.7- to 165-fold. Impressively,
the crystals prepared under optimized conditions by normal approaches
can be further enlarged by the isotope effect, yielding the largest
MOF single crystal (2.9 cm × 0.48 cm × 0.23 cm) among the
one-pot synthesis method. Detailed in situ characterizations
reveal that the isotope effect can retard crystallization kinetics,
establish a higher nucleation energy barrier, and consequently generate
fewer nuclei that eventually grow larger. Compared with the smaller
crystals, the isotope effect-enlarged crystal shows 33% improvement
in the X-ray dose rate detection limit. This work enriches the understanding
of the isotope effect on regulating the crystallization process and
provides inspiration for exploring potential applications of large
MOF single crystals