Ultrahigh extinction ratio and a low power silicon thermo-optic switch.

The silicon thermo-optic switch (TOS) is one of the most fundamental and crucial blocks in large-scale silicon photonic integrated circuits (PICs). An energy-efficient silicon TOS with ultrahigh extinction ratio can effectively mitigate cross talk and reduce power consumption in optical systems. In this Letter, we demonstrate a silicon TOS based on cascading Mach-Zehnder interferometers (MZIs) with spiral thermo-optic phase shifters. The experimental results show that an ultrahigh extinction ratio of 58.8 dB is obtained, and the switching power consumption is as low as 2.32 mW/π without silicon air trench. The rise time and fall time of the silicon TOS are about 10.8 and 11.2 µs, respectively. Particularly, the figure of merit (FOM) has been improved compared with previously reported silicon TOS. The proposed silicon TOS may find potential applications in optical switch arrays, on-chip optical delay lines, etc.

Efficient fabrication of bioinspired soft, ridged-slippery surfaces with large-range anisotropic wettability for droplet manipulation.

The droplet lossless directional motion control on slippery surfaces holds immense promise for applications in microfluidic chips, hazardous substance detection, chemical dispensing, etc. However, a significant challenge in this domain lies in efficiently developing soft, slippery surfaces with large-range anisotropic wettability and compatibility for curved scenarios. This study addressed this challenge through a quick 3D printing-assisted method to produce soft, ridged-slippery surfaces (SRSSs) as the droplet manipulation platform. The SRSSs demonstrated substantial anisotropic rolling resistances, measuring 116.9 µN in the perpendicular direction and 7.7 µN in the parallel direction, exhibiting a ratio of 15.2. Combining several extents of anisotropic wettability on a soft substrate could realize diverse reagent manipulation functions. Furthermore, these SRSSs showcased high compatibility with various droplet constituents, impressive liquid impact resistance, self-repair capability, and mechanical durability and thermal durability, ensuring exceptional applicability. As proofs of concept, the SRSSs were successfully applied in droplet control and classification for heavy metal ion detection, mechanical arm-based droplet grab and release, and cross-species transport, showcasing their remarkable versatility, compatibility, and practicality in advanced droplet microfluidic chips and water harvesting applications.

PKM2 promotes lymphatic metastasis of hypopharyngeal carcinoma via regulating epithelial-mesenchymal transition: an experimental research.

BACKGROUND: Patients with hypopharyngeal carcinoma (HPC) have a poor prognosis mainly because of lymphatic metastasis. This research aimed to determine the PKM2 role in lymphatic metastasis in HPC and the underlying molecular mechanism contributing to this phenomenon. METHODS: PKM2 in HPC was studied for its expression and its likelihood of overall survival using TCGA dataset. Western blotting, qRT-PCR, and IHC were employed to confirm PKM2 expression. Methods including gain- and loss-of-function were used to examine the PKM2 role in HPC metastasis in vitro and in vivo. In vitro and in vivo studies also confirmed lymphatic metastasis's mechanism. RESULTS: Prominent PKM2 overexpression was seen in patients with lymphatic metastasis of HPC, and there was an inherent relationship between a high PKM2 level and poor prognosis. In vitro research showed that knocking down PKM2 decreased tumor cell invasion, migration, and proliferation while promoting apoptosis and inhibiting epithelial-mesenchymal transition, but overexpressing PKM2 had the reverse effect. Animal studies suggested that PKM2 may facilitate tumor development and lymphatic metastasis. CONCLUSIONS: Our findings suggest that PKM2 may be a tumor's promoter gene of lymphatic metastasis, which may promote lymphatic metastasis of HPC by regulating epithelial-mesenchymal transition. PKM2 may be a biomarker of metastatic potential, ultimately providing a basis for exploring new therapeutic targets.

Recent Advances in Flexible CNC-Based Chiral Nematic Film Materials.

Cellulose nanocrystal (CNC) is a renewable resource derived from lignocellulosic materials, known for its optical permeability, biocompatibility, and unique self-assembly properties. Recent years have seen great progresses in cellulose nanocrystal-based chiral photonic materials. However, due to its inherent brittleness, cellulose nanocrystal shows limitations in the fields of flexible materials, optical sensors and food freshness testing. In order to solve the above limitations, attempts have been made to improve the flexibility of cellulose nanocrystal materials without destroying their structural color. Despite these progresses, a systematic review on them is lacking. This review aims to fill this gap by providing an overview of the main strategies and the latest research findings on the flexibilization of cellulose nanocrystal-based chiral nematic film materials (FCNM). Specifically, typical substances and methods used for their preparation are summarized. Moreover, different kinds of cellulose nanocrystal-based composites are compared in terms of flexibility. Finally, potential applications and future challenges of flexible cellulose nanocrystal-based chiral nematic materials are discussed, inspiring further research in this field.

Prognostic analysis of surgical treatment for T3 glottic laryngeal cancer based on different tumor extension patterns.

BACKGROUND AND OBJECTIVES: To investigate the prognostic impact of different tumor invasion patterns in the surgical treatment of T3 glottic laryngeal cancer. METHODS: We conducted a retrospective analysis of clinical data of 91 patients with T3 glottic laryngeal cancer. RESULTS: We found that the posterior invasion being significantly associated with involvement of the lamina of cricoid cartilage (P < 0.001), arytenoid cartilage (P = 0.001), and subglottic (P = 0.001). There was no statistical difference in survival outcomes between the total laryngectomy (TL) group and the partial laryngectomy (PL) group, but in the PL group, tumors with anterior invasion were associated with a better 5-year DFS than tumors with posterior invasion (HR: 4.681, 95% CI: 1.337-16.393, P = 0.016), and subglottic involvement was associated with worse LRRFS (HR: 3.931, 95% CI: 1.054-14.658, P = 0.041). At the same time, we found that involvement of the lamina of cricoid cartilage was an independent risk factor for postoperative laryngeal stenosis in PL patients (HR: 11.67, 95% CI: 1.89-71.98, P = 0.008). CONCLUSION: Selectively performed PL can also achieve favorable oncological outcomes comparable to those of TL. Posterior invasion and subglottic involvement are independent prognostic factors for recurrence after PL in T3 glottic laryngeal cancer, and involvement of the lamina of cricoid cartilage is associated with postoperative laryngeal stenosis. The tumor invasion pattern of patients with laryngeal cancer should be further subdivided to allow for selection of a more individualized treatment plan.

[Prognostic impact of different tumor invasion patterns in the surgical treatment of T3 glottic laryngeal cancer].

Objective:To investigate the prognostic impact of different tumor invasion patterns in the surgical treatment of T3 glottic laryngeal cancer. Methods:A retrospective analysis was conducted on the clinical data of 91 patients with T3 glottic laryngeal cancer. Results:Among the 91 patients, 58 cases （63.7%） had anterior invasion and 33 cases （36.3%） had posterior invasion. The posterior invasion was significantly correlated with invasions of the dorsal plate of cricoid cartilage （P<0.001）, arytenoid cartilage （P= 0.001）, and subglottic region（P = 0.001）. There was no statistical difference in survival outcomes between the total laryngectomy group and the partial laryngectomy group. But in the partial laryngectomy group, the 5-year disease-free survival（DFS） of patients with anterior invasive tumors was better than that of patients with posterior invasion tumors （HR: 4.681, 95%CI 1.337-16.393, P=0.016）, and subglottic invasion was associated with worse loco-regional recurrence-free survival（LRRFS）（HR: 3.931, 95%CI 1.054-14.658, P=0.041）. At the same time, we found that involvement of the dorsal plate of cricoid cartilage was an independent risk factor for postoperative laryngeal stenosis in partial laryngectomy patients （HR:11.67, 95%CI 1.89-71.98,P=0.008）. Conclusion:Compared with total laryngectomy, selected partial laryngectomy can also achieve favorable oncological outcomes. Posterior invasion and subglottic extension are independent prognostic factors for recurrence of partial laryngectomy in T3 glottic laryngeal cancer, and the involvement of the dorsal plate of cricoid cartilage is associated with postoperative laryngeal stenosis. The tumor invasion pattern of laryngeal cancer should be further subdivided in order to select a more individualized treatment plan.

[Clinical analysis of diversity of defect repair with supraclavicular island flap after head and neck tumor surgery].

Objective:To investigate the diversity and clinical effect of supraclavicular island flap in repairing the defect after head and neck tumor surgery. Methods:A retrospective analysis was performed on 30 patients who received the repair of head and neck defects with supraclavicular island flaps at Department of Otorhinolaryngology Head and Neck Surgery of the First Affiliated Hospital of Chongqing Medical University from January 2017 to March 2023. The sites and types of defects, intraoperative blood loss, time of flaps preparation, areas of flaps, survival of the flaps and other complications were recorded. Results:A total of 30 patients were enrolled, including 26 males and 4 females, aged 36-82 years. Among them, 22 patients with hypopharyngeal partial defect were repaired （19 patients with ipsilateral defect and 3 patients with contralateral defect）. In addition, 2 patients were repaired with contralateral pectoralis major musculocutaneous flap around the hypopharynx, the neck skin defect was repaired in 2 patients, the parotid skin defect was repaired in 2 patients, the temporal bone skin defect was repaired in 1 patient, and the cervical esophageal defect was repaired in 1 patient. The average blood loss during the operation was 8 ml, and the average time was 32 min. The flap areas ranged from 5.0 cm×4.0 cm to 20.0 cm×8.0 cm. 27 of 30 flaps survived（90.0%）, and pharyngeal fistula occurred in 6 patients after operation（4 flaps survived after local dressing）. One patient was complicated with venous thrombosis（the flap necrosis after local dressing）. Shoulder and neck functions（lift, internal rotation and abduction） were not significantly affected in 29 patients, and the function of 1 patient with shoulder infection was not affected after treatment. Conclusion:Supraclavicular island flap is a highly vascularized axial fascial flap. It is easy to make, thin, and soft in texture, and can be used to repair different sites and types of postoperative head and neck tumor defects with a low donor site complication rate. Good results in post-operative repair of head and neck tumors are worth promoting.

Mechanism of Yushenhuoxue prescription in treating endometriosis based on network pharmacology and the effect on the TNF pathway.

Endometriosis is a common disease in the field of gynaecology, exhibiting clinical manifestations such as dysmenorrhoea, pelvic masses, and infertility, affecting 2-10% of women of reproductive age worldwide. Currently, the acceptance rate of hormonal drugs in patients is low and certain side effects exist. In this study, based on network pharmacology, it was found that the Yushenhuoxue (YSHX) formula could potentially affect endometriosis through the TNF signalling pathway. Clinical studies indicated that YSHX demonstrated the ability to reduce the vas score of dysmenorrhoea, resulting in a significant down-regulation of serum ca125 and inflammatory factors (IL-6, IL-1ß, TNF-α). In vivo studies showed that stem cell mice in the YSHX group exhibited significantly reduced lesion volumes than those in the model group. Serum levels of IL-1ß and IL-6 were significantly decreased. Moreover, the phosphorylation levels of NF-κB p65 and the expression of TNF-α protein were significantly decreased. In vitro studies have shown that YSHX inhibits the proliferation, invasion, and migration of endometriotic cells. This study partially verified that YSHX contributed to the treatment of endometriosis by regulating the TNF signalling pathway and improving the inflammatory state of endometriosis.

[Significance of neoadjuvant immunotherapy combined with chemotherapy in the treatment of larynx preservation in locally advanced hypopharyngeal squamous cell carcinoma].

Objective:To evaluate the clinical significance of neoadjuvant immunotherapy combined with chemotherapy in the treatment of larynx preservation in locally advanced hypopharyngeal squamous cell carcinoma. Methods:Patients with locally advanced HPSCC（cT3-T4aN0-N3M0） were eligible. All received 2 cycles of pembrolizumab combined with docetaxel and platinum neoadjuvant induction therapy. After two cycles, the efficacy was evaluated, followed by radical chemoradiotherapy or surgery and adjuvant chemoradiotherapy according to the efficacy. The primary endpoints were objective response rate（ORR） ，larynx-preservation（LP） rate at 3 months post-treatment and the adverse reactions during neoadjuvant therapy. Results:From December 2021 to December 2022, 10 patients with locally advanced HPSCC（cT3-T4aN0-N3M0） were enrolled. After 2 cycles of the neoadjuvant therapy, 2 patients achieved complete response（CR）, 7 patients achieved partial response（PR）, 1 patient was stable disease（SD）, objective response rate（ORR） was 90%, and disease control rate（DCR） was 100%. 5 patients received radical chemoradiotherapy, 5 patients received surgery and adjuvant chemoradiotherapy, four of them received partial laryngectomy and partial hypopharyngeal resection surgery, and one of them received total laryngectomy and partial hypopharyngeal resection surgery. All patients were able to withstand adverse reactions of neoadjuvant therapy and successfully completed the whole treatment of HPSCC without grade 3-4 treatment-related adverse reactions. There was no recurrence or metastasis during 3-18 months of follow-up. 1 patient died of severe pneumonia 3 months after the completion of radical chemoradiotherapy. At 3 months after treatment, the larynx-preservation rate was 80%. Conclusion:Neoadjuvant immunotherapy combined with chemotherapy has good short-term efficacy and the adverse reactions were tolerable. It can improve the larynx-preservation rate of patients with locally advanced HPSCC, thus improving the prognosis and quality of life of patients.

Tunable bandpass microwave photonic filter with largely reconfigurable bandwidth and steep shape factor based on cascaded silicon nitride micro-ring resonators.

Bandpass microwave photonic filter (MPF) can be achieved based on the well-known phase to intensity conversion method by using phase modulation and single micro-ring resonator (MRR) notch filter. Since MRR could introduce residual phase in handling one optical sideband, the out-of-band radio frequency (RF) rejection ratio and the shape factor of the bandpass MPF are very limited. Here, by introducing another MRR to handle the other optical sideband, the residual phase can be greatly suppressed, thus the filter's performance can be greatly improved. The proposed bandpass MPF was both verified theoretically and experimentally. Compared with the single MRR, the out-of-band RF rejection ratio and the shape factor were improved by 20 dB and 1.67, respectively. Furthermore, the bandpass MPF's bandwidth is reconfigurable by adjusting the optical carrier's frequency or the two MRRs' amplitude coupling coefficients. The bandpass MPF's center frequency is also tunable by changing the resonant wavelengths of two MRRs in the opposite direction simultaneously. Experimentally, bandwidth reconfiguration from 0.38 GHz to 15.74 GHz, the shape factor optimization from 2 to 1.23, and frequency tuning from 4 GHz to 21.5 GHz were achieved. We believe that the proposed bandpass MPF has great potential for microwave photonic signal processing.

HSP90AA1 promotes lymphatic metastasis of hypopharyngeal squamous cell carcinoma by regulating epithelial-mesenchymal transition.

Background: Lymphatic metastasis (LM) emerges as an independent prognostic marker for hypopharyngeal squamous cell carcinoma (HSPSCC), chiefly contributing to treatment inefficacy. This study aimed to scrutinize the prognostic relevance of HSP90AA1 and its potential regulatory mechanism of concerning LM in HPSCC. Methods: In a preceding investigation, HSP90AA1, a differential gene, was discovered through transcriptome sequencing of HPSCC tissues, considering both the presence and absence of LM. Validation of HSP90AA1 expression was accomplished via qRT-PCR, western-blotting(WB), and immunohistochemistry(IHC), while its prognostic significance was assessed employing Kaplan-Meier survival analysis(KMSA), log-rank test(LR), and Cox's regression analysis(CRA). Bioinformatics techniques facilitated the prediction and analysis of its plausible mechanisms in LM, further substantiated by in vitro and in vivo experiments utilizing FaDu cell lines. Results: HSP90AA1 is substantially up-regulated in HPSCC with LM and is identified as an independent prognostic risk determinant. The down-regulation of HSP90AA1 can achieve inhibition of tumor cell proliferation, migration and invasion. Both in vivo experiments and Bioinformatics exploration hint at promoting LM by Epithelial-mesenchymal transition (EMT), regulated by HSP90AA1. Conclusions: HSP90AA1, by controlling EMT, can foster LM in HPSCC.This finding sets the foundation for delving into new therapeutic targets for HPSCC.

Pedicled thoracoacromial artery compound flaps for circumferential hypopharyngeal reconstruction.

BACKGROUND: Total laryngeal and hypopharyngeal resection remained to be the mainly treatment option for advanced hypopharyngeal cancer, which resulted in complicated reconstructive challenge for circumferential hypopharyngeal defect. The pedicled thoracoacromial artery compound flaps included Thoracoacromial artery perforator (TAAP) flap and pectoralis major myocutaneous (PMMC) flap. This study is to evaluate the clinical application of the pedicled thoracoacromial artery compound flaps for circumferential hypopharyngeal reconstruction. METHODS: From May 2021 to April 2022, four hypopharyngeal cancer patients with circumferential hypopharyngeal defects were reconstructed by the pedicled thoracoacromial artery compound flaps. All patients were males. Patient age ranged from 35 to 62 years (average, 50 years). The Shoulder function were evaluated by SPADI. The average follow-up was 10.25 months (range from 4 to 18 months). RESULTS: All of the pedicled thoracoacromial artery compound flaps in our study survived. The defect length between tongue base and cervical esophagus ranged from 8 to 10 cm after total laryngeal and hypopharyngeal resection. The TAAP flap size ranged from 6 × 7 cm to 7 × 10 cm, and the PMMC flap size ranged from 6 × 7 cm to 9 × 12 cm. The pedicle length of TAAP and PMMC flaps varied, respectively, from 5 to 8 cm (mean 6.5 cm) and 7 cm to 11 cm (mean 8.75 cm). The mean time of TAAP and PMMC flaps harvest was, respectively, 82 min and 39 min. All patients were able to resume soft diet in the fourth week of postoperation, but one patient was operated by gastrostomy in the second month of postoperation because of pharyngeal cavity stenosis, and the patient successfully resumed oral soft diet by endoscopic balloon dilation after postoperation radiotherapy. All patients have resumed oral feeding at last. There were mild dysfunction for our patients according to SPADI during the mid-long follow-up. CONCLUSIONS: The pedicled thoracoacromial artery compound flaps have stable blood supply and provide adequate muscle coverage for greater protection during radiotherapy, and the microsurgical skills have no requirement. Therefore, the compound flaps provide a good choice for the reconstruction of circumferential hypopharyngeal defect, especially in the aged or patients with comorbidities who are not able to tolerate prolonged surgery.

miR-19a mediates the mechanism by which SPHK2 regulates hypopharyngeal squamous cell carcinoma progression through the PI3K/AKT axis.

This study explored the expression of sphingosine kinase 2 (SPHK2) and microRNA miR-19a-3p (miR-19a-3p) in patients with Hypopharyngeal squamous cell carcinoma (HSCC) together with pathways affecting HSCC invasion and metastasis. Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting (WB) were performed to assess the differential expression of SPHK2 and miR-19a-3p in patients with HSCC lymph node metastasis (LNM). Immunohistochemical (IHC) results were analyzed together with clinical information to evaluate their clinical significance. Subsequently, the functional effects of SPHK2 overexpression and knockdown on FaDu cells were evaluated in in vitro experiments. We performed in vivo experiments using nude mouse to assess the effects of SPHK2 knockdown on tumor formation, growth and LNM. Finally, we explored upstream and downstream signaling pathways associated with SPHK2 in HSCC. SPHK2 was significantly elevated in HSCC patients with LNM and survival was lower in patients with enhanced SPHK2 expression (P < 0.05). We also demonstrated that SPHK2 overexpression accelerated the proliferation, migration, and invasion. Using animal models, we further verified that SPHK2 deletion abrogated tumor growth and LNM. In terms of mechanism, we found that miR-19a-3p was significantly reduced in HSCC patients with LNM and was negatively associated with SPHK2. MiR-19a-3p and SPHK2 could regulate tumor proliferation and invasion through the PI3K/AKT axis. SPHK2 was found to contribute significantly to both LNM and HSCC patient prognosis and was shown to be an independent risk factor for LNM and staging in HSCC patients. The miR-19a-3p/SPHK2/PI3K/AKT axis was found to contribute to the development and outcome of HSCC.

ANXA6/TRPV2 axis promotes lymphatic metastasis in head and neck squamous cell carcinoma by inducing autophagy.

BACKGROUND: Head and neck squamous cell carcinoma (HNSCC) is highly aggressive with a significant tropism of lymph nodes, which restricts treatment options and negatively impacts patient outcomes. Although progress has been made in understanding the molecular mechanisms underlying lymphatic metastasis (LM), these mechanisms remain elusive. ANXA6 is a scaffold protein that participates in tumor pathogenesis and autophagy regulation; however, how ANXA6 affects autophagy and LM in HNSCC cells remains unknown. METHODS: RNA sequencing was performed on HNSCC clinical specimens with or without metastasis as well as on The Cancer Genome Atlas dataset to investigate ANXA6 expression and survival. Both in vitro and in vivo studies were performed to investigate the role of ANXA6 in the regulation of LM in HNSCC. The molecular mechanism by which ANXA6 interacts with TRPV2 was examined at the molecular level. RESULTS: ANXA6 expression was significantly upregulated in HNSCC patients with LM and higher expression was associated with poor prognosis. ANXA6 overexpression promoted the proliferation and mobility of FaDu and SCC15 cells in vitro; however, ANXA6 knockdown retarded LM in HNSCC in vivo. ANXA6 induced autophagy by inhibiting the AKT/mTOR signaling pathway in HNSCC, thereby regulating the metastatic capability of the disease. Furthermore, ANXA6 expression positively correlated with TRPV2 expression both in vitro and in vivo. Lastly, TRPV2 inhibition reversed ANXA6-induced autophagy and LM. CONCLUSIONS: These results indicate that the ANXA6/TRPV2 axis facilitates LM in HNSCC by stimulating autophagy. This study provides a theoretical basis for investigating the ANXA6/TRPV2 axis as a potential target for the treatment of HNSCC, as well as a biomarker for predicting LM.

Relationship between the Co-Continuous Morphology of Immiscible Polymer Blends and the Structure of an In Situ Formed Graft Copolymer.

In order to get stable co-continuous morphology in immiscible polymer blends, besides reducing the interfacial tension, the compatibilizer should not only promote the formation of flat interface between different phases, but also not hinder the coalescence of the dispersed phase. Herein, the relationship between the morphology of the compatibilized polystyrene/nylon 6/styrene-maleic anhydride (PS/PA6/SMA) immiscible polymer blends and the structures of the in-situ formed SMA-g-PA6 graft copolymers as well as the processing conditions are studied. Two kinds of SMA are used: SMA28 (28 wt.% MAH) and SMA11 (11 wt.% MAH). After melt blending with PA6, the in-situ formed copolymer SMA28-g-PA6 has on average of four PA6 side chains, while that of SMA11-g-PA6 has only one. Dissipative particle dynamics simulation results indicate that both SMA28-g-PA6 copolymer and PS/PA6/SMA28 blends tend to form co-continuous structure, while those related to SMA11 intend to form sea-island morphologies. These results are correct only at relatively low rotor speed (60 rpm). When the rotor speed is higher (105 rpm), sea-island morphologies are obtained in SMA28 systems, while that for SMA11 ones are co-continuous. This indicates that higher shear stress can elongate the minor phase domains to form flat interfaces, while the SMA28-g-PA6 copolymers can be pulled out from the interface.

Correction: Recent advances in self-healing polyurethane based on dynamic covalent bonds combined with other self-healing methods.

Correction for 'Recent advances in self-healing polyurethane based on dynamic covalent bonds combined with other self-healing methods' by Ze-Wei An et al., Nanoscale, 2023, 15, 6505-6520, https://doi.org/10.1039/D2NR07110J.

Self-Healable, Solvent Response Cellulose Nanocrystal/Waterborne Polyurethane Nanocomposites with Encryption Capability.

Cellulose nanocrystal (CNC)-based chiral nematic structure is widely used in stimulus response and sensing. A popular area of research is enhancing the mechanical characteristics and environmental adaptability of chiral nematic materials. In this paper, a flexible photonic film with self-healing ability (FPFS) was prepared by combining waterborne polyurethane containing dynamic covalent disulfide bonds (SSWPU) with CNC. The results found that the FPFS showed excellent toughness under the action of stretching, bending, twisting, and folding. The FPFS exhibited an amazing self-healing efficiency, which can be self-healed within 2 h at room temperature. Moreover, the FPFS could respond immediately and produce reversible color change when it was soaked in typical solvents. In addition, when ethanol was used as ink to paint on the FPFS, a visible pattern only under polarized light was formed. This study offers fresh perspectives in the areas of self-healing, biological anticounterfeiting, solvent response, and flexible photonic materials.

Recent advances in self-healing polyurethane based on dynamic covalent bonds combined with other self-healing methods.

To meet more application requirements, improving mechanical properties and self-healing efficiency has become the focus of current research on self-healing PU. The competitive relationship between self-healing ability and mechanical properties cannot be avoided by a single self-healing method. To address this problem, a growing number of studies have combined dynamic covalent bonding with other self-healing methods to construct the PU structure. This review summarizes recent studies on PU materials that combine typical dynamic covalent bonds with other self-healing methods. It mainly includes four parts: hydrogen bonding, metal coordination bonding, nanofillers combined with dynamic covalent bonding and multiple dynamic covalent bond bonding. The advantages and disadvantages of different self-healing methods and their significant role in improving self-healing ability and mechanical properties in PU networks are analyzed. At the same time, the possible challenges and research directions of self-healing PU materials in the future are discussed.

Frequency-selectable microwave generation based on on-chip switchable spectral shaping and wavelength-to-time mapping.

We propose and experimentally demonstrate a scheme for the photonic generation of pulsed microwave signals with selectable frequency based on spectral shaping and wavelength-to-time mapping (WTTM) technique. The frequency selectivity is realized by channel switching on an integrated silicon-on-insulator (SOI) spectral shaping chip. The incident signal is spectrally shaped by the asymmetric Mach-Zehnder interferometer (MZI) in the selected channel, and an optical spectrum with uniform free spectral range (FSR) can be generated in a broad bandwidth up to dozens of nanometers, implying large microwave signal duration after WTTM if a pulse light source with matched bandwidth is available. Microwave pulses of frequency from 3.6 GHz to 28.4 GHz with a fixed interval are experimentally generated respectively. The realization of eight microwave frequencies selectable with only one shared dispersive element (DE) required indicates high expansibility in the frequency cover range of our scheme by tuning the dispersion value in WTTM.

Spectra reconfiguration of a silicon microring resonator via double injection with different angles.

A reconfigurable silicon microring filter, which is constructed by cascading a tunable Mach-Zehnder interferometer and a double injected silicon microring resonator with a variable input angle, is proposed and investigated. The spectra reconfigurations of the optical filter were simulated and analyzed using the transmission matrix method. The results show that when keeping the perimeter of the microring constant, the free spectral range (FSR) of the filter can be multiplied by adjusting the angle between the two injections. Moreover, by changing the coupling coefficients of the microring and the optical power ratio between the two injections, different types of spectral responses such as square, sinusoidal, and flat-top interleaver can be obtained. The device is simple and easy to integrate, and its capabilities to expand the FSR and spectral reconfiguration may have great potential in reconfigurable integrated optic chips.