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Multimode interference (MMI) couplers based on silicon slot-waveguide structures have received widespread attention in recent years. The key issues that need to be addressed are the size and loss of such devices. This study introduces a 1 × 3 silicon-based slot-waveguide multimode interference power splitter. The device uses a gallium-nitride slot-waveguide structure to reduce the length of the coupling region and decrease additional losses. To reduce the width of the coupling region, the multimode interference coupling area is designed with a parabolic-shaped structure. The introduction of a tapered structure between the input/output waveguides and the coupling region improves additional losses and non-uniformity. Furthermore, we conducted an analysis of the fabrication tolerances of the coupling region. In this paper, we use mode solution to simulate the design of the device in the 1550 nm optical wavelength range. The eigenmode expansion method is used to simulate and optimize the parameters of the device. The device is simulated using the eigenmode expansion solver. The simulation results show that the total length of the coupling region for the device is only 4 μm. The normalized transmission of the device is 0.992, and its excess loss and imbalance are 0.036 dB and 0.003 dB, respectively. The proposed power splitter can be applied to integrated optical circuit design, optical sensing, and optical power measurement. [ABSTRACT FROM AUTHOR]

Optical power splitters (OPSs) are utilized extensively in integrated photonic circuits, drawing significant interest in research on power splitters with adjustable splitting ratios. This paper introduces a compact, low-loss 1 × 2 asymmetric multimode interferometric (MMI) optical power splitter on a silicon-on-insulator (SOI) platform. The device is simulated using the finite difference method (FDM) and eigenmode expansion solver (EME). It is possible to attain various output power splitting ratios by making the geometry of the MMI central section asymmetric relative to the propagation axis. Six distinct optical power splitters are designed with unconventional splitting ratios in this paper, which substantiates that the device can achieve any power splitter ratios (PSRs) in the range of 95:5 to 50:50. The dimensions of the multimode section were established at 2.9 × (9.5–10.9) μm. Simulation results show a range of unique advantages of the device, including a low extra loss of less than 0.4 dB, good fabrication tolerance, and power splitting ratio fluctuation below 3% across the 1500 nm to 1600 nm wavelength span. [ABSTRACT FROM AUTHOR]

The microRNAs, which are small RNAs of 18–25 nt in length, act as key regulatory factors in posttranscriptional gene expression during plant growth and development. However, little is known about their regulatory roles in response to stressful environments in birch (Betula platyphylla). Here, we characterized and further explored miRNAs from osmotic- and salt-stressed birch. Our analysis revealed a total of 190 microRNA (miRNA) sequences, which were classified into 180 conserved miRNAs and 10 predicted novel miRNAs based on sequence homology. Furthermore, we identified Bp-miR408a under osmotic and salt stress and elucidated its role in osmotic and salt stress responses in birch. Notably, under osmotic and salt stress, Bp-miR408a contributed to osmotic and salt tolerance sensitivity by mediating various physiological changes, such as increases in reactive oxygen species accumulation, osmoregulatory substance contents and Na+ accumulation. Additionally, molecular analysis provided evidence of the in vivo targeting of BpBCP1 (blue copper protein) transcripts by Bp-miR408a. The overexpression of BpBCP1 in birch enhanced osmotic and salt tolerance by increasing the antioxidant enzyme activity, maintaining cellular ion homeostasis and decreasing lipid peroxidation and cell death. Thus, we reveal a Bp-miR408a – BpBCP1 regulatory module that mediates osmotic and salt stress responses in birch. [ABSTRACT FROM AUTHOR]

Summary: Glycine‐rich RNA‐binding proteins (GRPs) have been implicated in the responses of plants to environmental stresses, but the function of GRP genes involved in salt stress and the underlying mechanism remain unclear. In this study, we identified BpGRP1 (glycine‐rich RNA‐binding protein), a Betula platyphylla gene that is induced under salt stress. The physiological and molecular responses to salt tolerance were investigated in both BpGRP1‐overexpressing and suppressed conditions. BpGRF3 (growth‐regulating factor 3) was identified as a regulatory factor upstream of BpGRP1. We demonstrated that overexpression of BpGRF3 significantly increased the salt tolerance of birch, whereas the grf3‐1 mutant exhibited the opposite effect. Further analysis revealed that BpGRF3 and its interaction partner, BpSHMT, function upstream of BpGRP1. We demonstrated that BpmiR396c, as an upstream regulator of BpGRF3, could negatively regulate salt tolerance in birch. Furthermore, we uncovered evidence showing that the BpmiR396c/BpGRF3 regulatory module functions in mediating the salt response by regulating the associated physiological pathways. Our results indicate that BpmiR396c regulates the expression of BpGRF3, which plays a role in salt tolerance by targeting BpGRP1. [ABSTRACT FROM AUTHOR]

A design method for highly‐selective bandpass filters based on novel dual‐mode fan‐shaped patch resonator (FSPR) is presented in this article. Different from traditional dual‐mode patch filters, two higher‐order modes TM020 and TM110 are utilised to generate a passband, and the two resonant frequencies can be controlled well by its radius and angle. A dual‐mode filter with two transmission zeros (TZs) is implemented by using one FSPR, and locations of TZs can be controlled well. To further improve the selectivity of FSPR filters, four‐pole filters based on two identical dual‐mode FSPRs with co‐directional and reverse‐directional cascade are simulated, fabricated and measured. Furthermore, three‐ and four‐pole filters based on dual‐mode FSPR and single‐mode uniform impedance resonators are proposed, which are also simulated, fabricated, and measured. The later proposed filters not only achieve high selectivity and wide stopband, but also have simple structure and small size. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) is a toxic metal that affects the normal growth and development of plants. Roots may directly contact Cd and thus serve as the first barrier in the defense responses of plants. In this study, Tamarix hispida (T. hispida) roots treated with 150 μM CdCl2 were collected for RNA-seq. A total of 2004 differentially expressed genes (DEGs) were identified at different time points. Kyoto Encyclopedia of Genes and Genomes enrichment revealed that the DEGs were significantly enriched in phenylpropanoid biosynthesis, flavonoid biosynthesis and other metabolic pathways. To explore the regulatory role of transcription factors (TFs) involved in the Cd stress response, a multilayer hierarchical gene regulatory network (ML-hGRN) was constructed, including 53 TFs and 54 structural genes in ML-hGRN, with 341 predicted regulatory relationships. Binding of DRE1A , MYC1 , FEZ , ERF4 and ERF17 to predicted target genes was detected by ChIP-PCR, and DRE1A , MYC1 and FEZ were transiently overexpressed in T. hispida. The results suggest that these TFs play a key role in the Cd stress response by scavenging reactive oxygen species. In conclusion, this study predicts some Cd-responsive TFs that may have an important function under Cd stress and provides useful information for molecular breeding. [ABSTRACT FROM AUTHOR]

Polyurethane materials have good biocompatibility, blood compatibility, mechanical properties, fatigue resistance and processability, and have always been highly valued as medical materials. Polyurethane fibers prepared by electrostatic spinning technology can better mimic the structure of natural extracellular matrices (ECMs), and seed cells can adhere and proliferate better to meet the requirements of tissue repair and reconstruction. The purpose of this review is to present the research progress of electrostatically spun polyurethane fibers in bone tissue engineering, skin tissue engineering, neural tissue engineering, vascular tissue engineering and cardiac tissue engineering, so that researchers can understand the practical applications of electrostatically spun polyurethane fibers in tissue engineering and regenerative medicine.