An optically resolvable and thermally chiral‐switchable device for circularly polarized luminescence (CPL) is first constructed using a light‐emitting conjugated polymer film and a double‐layered ...chiral nematic liquid crystal (N*‐LC) cell. The double‐layered N*‐LC cell with opposite handedness at each layer is fabricated by adding each of two types of N*‐LCs into each of the cells, and the N*‐LCs consist of nematic LCs and chiral dopants with opposite chirality and different mole concentrations. The selective reflection band due to the N*‐LC is thermally shifted so that the band wavelength is close to the luminescence band of the racemic conjugated polymer, such as disubstituted polyacetylene (diPA), yielding CPL with opposite handedness and high dissymmetry factor values (|glum|) of 1.1–1.6 at low and high temperatures. The double‐layered N*‐LC cell bearing the temperature‐controlled selective reflection is useful for generating CPLs from racemic fluorescent materials and for allowing thermal chirality‐switching in CPLs, which present new possibilities for optoelectronic and photochemical applications.
An optically resolvable and thermally chiral‐switchable device for circularly polarized luminescence (CPL) is constructed using a light‐emitting conjugated polymer film and a double‐layered cell of chiral nematic liquid crystal (N*‐LC) with opposite handedness at each layer. The chirality switching of the CPL is achieved via selective reflections of the N*‐LCs with different helical senses.
The circularly polarized luminescence (CPL) of chiral disubstituted liquid‐crystalline polyacetylene (di‐LCPA) can be dynamically switched and amplified from left‐ to right‐handed CPL and vice versa ...through the selective transmission of CPL across a thermotropic chiral nematic liquid crystal (N*‐LC) phase. By combining a chiral di‐LCPA CPL‐emitting film with an N*‐LC cell and tuning the selective reflection band of the N*‐LC phase to coincide with the CPL emission band, a CPL‐switchable cell was constructed. The phase change induced by the thermotropic N*‐LC cell by varying the temperature leads to a change in the selective transmission of CPL, which enables the dynamic switching and amplification of CPL. It is anticipated that CPL‐switchable devices might find applications in switchable low‐threshold lasers and optical memory devices.
The circularly polarized luminescence (CPL) of chiral disubstituted liquid‐crystalline polyacetylene (di‐LCPA) was dynamically switched and amplified through the selective transmission of CPL across a thermotropic chiral nematic liquid crystal (N*‐LC) phase. By combining a chiral di‐LCPA CPL‐emitting film with an N*‐LC cell, a CPL‐switchable cell was constructed.
Data-driven rolling-bearing fault diagnosis methods are mostly based on deep-learning models, and their multilayer nonlinear mapping capability can improve the accuracy of intelligent fault ...diagnosis. However, problems such as gradient disappearance occur as the number of network layers increases. Moreover, directly taking the raw vibration signals of rolling bearings as the network input results in incomplete feature extraction. In order to efficiently represent the state characteristics of vibration signals in image form and improve the feature learning capability of the network, this paper proposes fault diagnosis model MTF-ResNet based on a Markov transition field and deep residual network. First, the data of raw vibration signals are augmented by using a sliding window. Then, vibration signal samples are converted into two-dimensional images by MTF, which retains the time dependence and frequency structure of time-series signals, and a deep residual neural network is established to perform feature extraction, and identify the severity and location of the bearing faults through image classification. Lastly, experiments were conducted on a bearing dataset to verify the effectiveness and superiority of the MTF-ResNet model. Features learned by the model are visualized by t-SNE, and experimental results indicate that MTF-ResNet showed better average accuracy compared with several widely used diagnostic methods.
Double-layered manganites are natural superlattices with low thermal conductivity, which is of importance for potential thermoelectric applications. The Gd2−2xSr1+2xMn2O7 (x = 0.5; 0.625; 0.75) were ...prepared by the solid-state reaction method. All the samples crystallize in the tetragonal I4/mmm Sr3Ti2O7 type structure. The unit cell volume and the distortion in the MnO6 octahedra increase with increasing Gd content. Their thermoelectric properties were investigated between 300 and 1200 K. All exhibit an n-type semiconducting behavior. The electrical conductivity (σ) increases while the absolute value of the Seebeck coefficient (|S|) decreases with increasing Gd content. Simultaneous increases in σ and |S| with increasing temperature are observed at temperatures approximately higher than 600 K, and the power factor reaches a maximum value of 18.36 μW/(m K²) for x = 0.75 at 1200 K. The thermal conductivity (κ) is lower than 2 W/(m K) over the temperature range of 300–1000 K for all the samples and a maximum dimensionless figure of merit ZT of 0.01 is obtained for x = 0.75 at 1000 K.
The mechanical properties of eutectic high entropy alloys (EHEAs) can be significantly improved by adjusting its microstructure; however, the conventional adjustment approaches are inefficient and ...trapped in a strength-ductility tradeoff. In this study, we applied a compressive stress of 350 MPa (about 60 % yield strength) with ultrasonic vibration of 20 kHz frequency and 20 μm amplitude on an AlCoCrFeNi2.1 EHEA for different processing time. The ultimate tensile strength and total elongation of the EHEA were prominently enhanced to 1050 MPa and 27.4 % after 20 min ultrasonic processing, representing an increment of 17 % and 54 % from the initial state (900 MPa and 17.8 %), realizing the synergistic enhancement of both strength and ductility. The structural analysis of the ultrasonically processed AlCoCrFeNi2.1 EHEA shows that the strengthening effect induced by BCC(B2) precipitates with a typical size of 1 μm provoked by ultrasonic vibration was the primary reason for the enhanced strength. The synchronous deformation of alternating soft FCC(L12) phase and hard BCC(B2) phase as well as the motivated multiple slip systems intensified the strain hardening effect, resulting in the improvement of strength-ductility synergy. This study provided a new and efficient way to overcome the strength-ductility tradeoff and prepare a EHEAs with high mechanical properties.
Bi-based YbMg2Bi1.98 Zintl compounds represent promising thermoelectric materials. Precise composition and appropriate doping are of great importance for this complex semiconductor. Here, the ...influence of Zn substitution for Mg on the microstructure and thermoelectric properties of p-type YbMg1.85−xZnxBi1.98 (x = 0, 0.05, 0.08, 0.13, 0.23) was investigated. Polycrystalline samples were prepared using induction melting and densified with spark plasma sintering. X-ray diffraction confirmed that the major phase of the samples possesses the trigonal CaAl2Si2-type crystal structure, and SEM/EDS indicated the presence of minor secondary phases. The electrical conductivity increases and the lattice thermal conductivity decreases with more Zn doping in YbMg1.85−xZnxBi1.98, whereas the Seebeck coefficient has a large reduction. The band gap decreases with increasing Zn concentration and leads to bipolar conduction, resulting in an increase in the thermal conductivity at higher temperatures. Figure of merit ZT values of 0.51 and 0.49 were found for the samples with x = 0 and 0.05 at 773 K, respectively. The maximum amount of Zn doping is suggested to be less than x = 0.1.
Xylem development plays a crucial role in wood formation in woody plants. In recent years, there has been growing attention towards the impact of brassinosteroids (BRs) on this xylem development. In ...the present study, we evaluated the dynamic variation of xylem development in Fraxinus mandshurica (female parent, M8) and a novel interspecific hybrid
×
(1601) from May to August 2020.
We obtained RNA-Seq transcriptomes of three tissue types (xylem, phloem, and leaf) to identify the differences in xylem-differentially expressed genes (X-DEGs) and xylem-specifically expressed genes (X-SEGs) in M8 and 1601 variants. We then further evaluated these genes via weighted gene co-expression network analysis (WGCNA) alongside overexpressing FmCPD, a BR biosynthesis enzyme gene, in transient transgenic
.
Our results indicated that the xylem development cycle of 1601 was extended by 2 weeks compared to that of M8. In addition, during the later wood development stages (secondary wall thickening) of 1601, an increased cellulose content (14%) and a reduced lignin content (11%) was observed. Furthermore, vessel length and width increased by 67% and 37%, respectively, in 1601 compared with those of M8. A total of 4589 X-DEGs were identified, including enzymes related to phenylpropane metabolism, galactose metabolism, BR synthesis, and signal transduction pathways. WGCNA identified hub X-SEGs involved in cellulose synthesis and BR signaling in the 1601 wood formation-related module
and
; in contrast, genes involved in phenylpropane metabolism were significantly enriched in the M8 wood formation-related module (
and
). Moreover, overexpression of
in transient transgenic
affected the expression of genes associated with lignin and cellulose biosynthesis signal transduction. Finally, BR content was determined to be approximately 20% lower in the M8 xylem than in the 1601 xylem, and the exogenous application of BRs (24-epi brassinolide) significantly increased the number of xylem cell layers and altered the composition of the secondary cell walls in
.
Our findings suggest that BR biosynthesis and signaling play a critical role in the differing wood development and properties observed between M8 and 1601
.
SQUAMOSA promoter binding protein-like (SPL) is a unique family of transcription factors in plants, which is engaged in regulating plant growth and development, physiological and biochemical ...processes. Fraxinus mandshurica is an excellent timber species with a wide range of uses in northeastern China and enjoys a high reputation in the international market. SPL family analysis has been reported in some plants while SPL family analysis of Fraxinus mandshurica has not been reported.
We used phylogeny, conserved motifs, gene structure, secondary structure prediction, miR156 binding sites, promoter cis elements and GO annotation to systematically analyze the FmSPLs family. This was followed by expression analysis by subcellular localization, expression patterns at various tissue sites, abiotic stress and hormone induction. Because FmSPL2 is highly expressed in flowers it was selected to describe the SPL gene family of Fraxinus mandshurica by ectopic expression. Among them, 10 FmSPL genes that were highly expressed at different loci were selected for expression analysis under abiotic stress (NaCl and Cold) and hormone induction (IAA and ABA). These 10 FmSPL genes showed corresponding trends in response to both abiotic stress and hormone induction. We showed that overexpression of FmSPL2 in transgenic Nicotiana tabacum L. resulted in taller plants, shorter root length, increased root number, rounded leaves, and earlier flowering time.
We identified 36 SPL genes, which were classified into seven subfamilies based on sequence analysis. FmSPL2 was selected for subsequent heterologous expression by analysis of expression patterns in various tissues and under abiotic stress and hormone induction, and significant phenotypic changes were observed in the transgenic Nicotiana tabacum L. These results provide insight into the evolutionary origin and biological significance of plant SPL. The aim of this study was to lay the foundation for the genetic improvement of Fraxinus mandshurica and the subsequent functional analysis of FmSPL2.
PDC (polycrystalline diamond compact) bit is the key equipment for drilling holes inside the rock in oil and mining industry. Inspired by the shape and structure of Capra sibirica horn, a bionic ...lateral PDC reamer bit with variable lateral reaming radius was developed. Side view of Capra sibirica horn was employed for fitting the horn shape curve based on picture processing method. PDC teeth were arranged on the horn shape blade imitating the transverse ridges on the horn to cut the rock material, found with only 30% utilization rate of the total teeth and load concentration of the last tooth. A bionic blade curve evolved from the Capra sibirica horn was defined with geometric method for the lateral reamer bit; the utilization rate of the teeth on the bionic blade curve was improved to 90% with uniformly distributed reaming load. Multigroup simulations were conducted with the finite element method; the effects of bit revolution speed and rotation feed speed of the bionic blade to reaming load were emphatically studied. Concrete sample was reamed indoors from 240 mm to 407 mm in diameter, and the bionic lateral PDC reamer bit was approved by the test result.
Based on the genetic algorithm (GA) incorporated with density functional theory (DFT) calculations, the structural and electronic properties of neutral and charged arsenic clusters As
(
= 2⁻24) are ...investigated. The size-dependent physical properties of neutral clusters, such as the binding energy, HOMO-LUMO gap, and second difference of cluster energies, are discussed. The supercluster structures based on the As₈ unit and As₂ bridge are found to be dominant for the larger cluster As
(
≥ 8). Furthermore, the possible geometric structures of As
, As
, and As
are predicted based on the growth pattern.
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