Advances in the understanding of circRNAs that influence viral replication in host cells.

Circular RNAs (circRNAs) are non-coding RNAs discovered in recent years, which are produced by back-splicing involving the 3' and 5' ends of RNA molecules. There is increasing evidence that circRNAs have important roles in cancer, neurological diseases, cardiovascular and cerebrovascular diseases, and other diseases. In addition, host circRNAs and virus-encoded circRNAs participate in the body's immune response, with antiviral roles. This review summarizes the mechanisms by which host and viral circRNAs interact during the host immune response. Comprehensive investigations have revealed that host circRNAs function as miRNA sponges in a particular manner, primarily by inhibiting viral replication. Viral circRNAs have more diverse functions, which generally involve promoting viral replication. In addition, in contrast to circRNAs from RNA viruses, circRNAs from DNA viruses can influence host cell migration, proliferation, and apoptosis, along with their effects on viral replication. In summary, circRNAs have potential as diagnostic and therapeutic targets, offering a foundation for the diagnosis and treatment of viral diseases.

Hydrolysis and Transport Characteristics of Phospholipid Complex of Alkyl Gallates: Potential Sustained Release of Alkyl Gallate and Gallic Acid.

Phospholipid complexes of alkyl gallates (A-GAs) including ethyl gallate (EG), propyl gallate (PG), and butyl gallate (BG) were successfully prepared by the thin film dispersion method. HPLC-UV analysis in an everted rat gut sac model indicated that A-GAs can be liberated from phospholipid complexes, which were further hydrolyzed by intestinal lipase to generate free gallic acid (GA). Both A-GAs and GA are able to cross the membrane, and the hydrolysis rate of A-GAs and the transport rate of GA are positively correlated with the alkyl chain length. Especially, compared with the corresponding physical mixtures, the phospholipid complexes exhibit slower sustained-release of A-GAs and GA. Therefore, the formation of phospholipid complexes is an effective approach to prolong the residence time in vivo and additionally enhance the bioactivities of A-GAs and GA. More importantly, through regulating the carbon skeleton lengths, controlled-release of alkyl gallates and gallic acid from phospholipid complexes will be achieved.

Two Birds with One Stone: V4 C3 MXene Synergistically Promoted VS2 Cathode and Zinc Anode for High-Performance Aqueous Zinc-Ion Batteries.

Aqueous zinc-ion batteries (AZIBs) are considered to be a rising star in the large-scale energy storage area because of their low cost and environmental friendliness properties. However, the limited electrochemical performance of the cathode and severe zinc dendrite of the anode severely hinder the practical application of AZIBs. Herein, a novel 3D interconnected VS2 ⊥V4 C3 Tx heterostructure material is prepared via one-step solvothermal method. Morphological and structural characterizations show that VS2 nanosheets are uniformly and dispersedly distributed on the surface of the V4 C3 MXene substrate, which can effectively suppress volume change of the VS2 . Owing to the open heterostructure along with the high conductivity of V4 C3 MXene, the VS2 ⊥V4 C3 Tx cathode shows a high specific capacity of 273.9 mAh g-1 at 1 A g-1 and an excellent rate capability of 143.2 mAh g-1 at 20 A g-1 . The V4 C3 MXene can also effectively suppress zinc dendrite growth when used as protective layer for the Zn anode, making the V4 C3 Tx @Zn symmetric cell with a stable voltage profile for ≈1700 h. Benefitting from the synergistic modification effect of V4 C3 MXene on both the cathode and anode, the VS2 ⊥V4 C3 Tx ||V4 C3 Tx @Zn battery exhibits a long cycling lifespan of 5000 cycles with a capacity of 157.1 mAh g-1 at 5A g-1 .

Transcriptional Analysis of lncRNA and Target Genes Induced by Influenza A Virus Infection in MDCK Cells.

BACKGROUND: The MDCK cell line is the primary cell line used for influenza vaccine production. Using genetic engineering technology to change the expression and activity of genes that regulate virus proliferation to obtain high-yield vaccine cell lines has attracted increasing attention. A comprehensive understanding of the key genes, targets, and molecular mechanisms of viral regulation in cells is critical to achieving this goal, yet the post-transcriptional regulation mechanism involved in virus proliferation-particularly the effect of lncRNA on influenza virus proliferation-is still poorly understood. Therefore, this study used high-throughput RNA-seq technology to identify H1N1 infection-induced lncRNA and mRNA expression changes in MDCK cells and explore the regulatory relationship between these crucial lncRNAs and their target genes. RESULTS: In response to H1N1 infection in MDCK cells 16 h post-infection (hpi) relative to uninfected controls, we used multiple gene function annotation databases and initially identified 31,501 significantly differentially expressed (DE) genes and 39,920 DE lncRNAs (|log2FC| > 1, p < 0.05). Among these, 102 lncRNAs and 577 mRNAs exhibited predicted correlations with viral response mechanisms. Based on the magnitude of significant expression differences, related research, and RT-qPCR expression validation at the transcriptional level, we further focused on 18 DE mRNAs and 32 DE lncRNAs. Among these, the differential expression of the genes RSAD2, CLDN1, HCLS1, and IFIT5 in response to influenza virus infection was further verified at the protein level using Western blot technology, which showed results consistent with the RNA-seq and RT-qPCR findings. We then developed a potential molecular regulatory network between these four genes and their six predicted lncRNAs. CONCLUSIONS: The results of this study will contribute to a more comprehensive understanding of the molecular mechanism of host cell non-coding RNA-mediated regulation of influenza virus replication. These results may also identify methods for screening target genes in the development of genetically engineered cell lines capable of high-yield artificial vaccine production.

CDC20 is a potential target gene to inhibit the tumorigenesis of MDCK cells.

MDCK is currently the main cell line used for influenza vaccine production in culture. Previous studies have reported that MDCK cells possess tumorigenic ability in nude mice. Although complete cell lysis can be ensured during vaccine production, host cell DNA released after cell lysis may still pose a risk for tumorigenesis. Greater caution is needed in the production of human vaccines; therefore, the use of gene editing to establish cells incapable of forming tumors may significantly improve the safety of influenza vaccines. Knowledge regarding the genes and molecular mechanisms that affect the tumorigenic ability of MDCK cells is crucial; however, our understanding remains superficial. Through monoclonal cell screening, we previously obtained a cell line, CL23, that possesses significantly reduced cell proliferation, migration, and invasion abilities, and tumor-bearing experiments in nude mice showed the absence of tumorigenic cells. With a view to exploring tumorigenesis-related genes in MDCK cells, DIA proteomics was used to compare the differences in protein expression between wild-type (M60) and non-tumorigenic (CL23) cells. Differentially expressed proteins were verified at the mRNA level by RT-qPCR, and a number of genes involved in cell tumorigenesis were preliminarily screened. Immunoblotting further confirmed that related protein expression was significantly reduced in non-tumorigenic cells. Inhibition of CDC20 expression by RNAi significantly reduced the proliferation and migration of MDCK cells and increased the proliferation of the influenza virus; therefore, CDC20 was preliminarily determined to be an effective target gene for the inhibition of cell tumorigenicity. These results contribute to a more comprehensive understanding of the mechanism underlying cell tumorigenesis and provide a basis for the establishment of target gene screening in genetically engineered non-tumorigenic MDCK cell lines.

Suspended cell lines for inactivated virus vaccine production.

INTRODUCTION: Inactivated virus vaccines are the most widely used tool to prevent disease. To meet vaccine production demands, increasing attention has been placed on identifying methods to improve vaccine production efficiency. The use of suspended cells can greatly increase vaccine production. Suspension acclimation is a traditional method to convert adherent cells to suspension strains. Furthermore, as genetic engineering technology has developed, increasing attention has focused on the development of suspension cell lines using targeted genetic engineering techniques. AREAS COVERED: This review systematically summarizes and analyzes the development and research progress of various inactivated viral vaccine production suspension cell lines and provides protocols and candidate target genes for the engineered establishment of additional suspension cell lines for vaccine production. EXPERT OPINION: The use of suspended cells can significantly improve the production efficiency of inactivated virus vaccines and other biological products. Presently, cell suspension culture is the key component to improve many vaccine production processes.

Carbon Foam-Supported VS2 Cathode for High-Performance Flexible Self-Healing Quasi-Solid-State Zinc-Ion Batteries.

As the new generation of energy storage systems, the flexible battery can effectively broaden the application area and scope of energy storage devices. Flexibility and energy density are the two core evaluation parameters for the flexible battery. In this work, a flexible VS2 material (VS2 @CF) is fabricated by growing the VS2 nanosheet arrays on carbon foam (CF) using a simple hydrothermal method. Benefiting from the high electric conductivity and 3D foam structure, VS2 @CF shows an excellent rate capability (172.8 mAh g-1 at 5 A g-1 ) and cycling performance (130.2 mAh g-1 at 1 A g-1 after 1000 cycles) when it served as cathode material for aqueous zinc-ion batteries. More importantly, the quasi-solid-state battery VS2 @CF//Zn@CF assembled by the VS2 @CF cathode, CF-supported Zn anode, and a self-healing gel electrolyte also exhibits excellent rate capability (261.5 and 149.8 mAh g-1 at 0.2 and 5 A g-1 , respectively) and cycle performance with a capacity of 126.6 mAh g-1 after 100 cycles at 1 A g-1 . Moreover, the VS2 @CF//Zn@CF full cell also shows good flexible and self-healing properties, which can be charged and discharged normally under different bending angles and after being destroyed and then self-healing.

Quadriceps strength and psychological readiness are associated with multiplanar knee kinematics after anterior cruciate ligament reconstruction.

BACKGROUND: Gait asymmetry, negative psychological factors and quadriceps strength deficits are common after anterior cruciate ligament reconstruction (ACLR). Whether quadriceps strength and psychological factors have impacts on multiplanar knee kinematics remains unclear. RESEARCH QUESTION: What are the relationships of multiplanar knee kinematics during the gait cycle and psychological readiness to quadriceps strength after ACLR? METHOD: In total, 45 patients were enrolled in this study at 8.3 ± 1.5 months after ACLR. All patients underwent gait analysis and isokinetic testing. Interlimb differences in the range of motion (ROM) and maximum and initial contact (IC) angles in abduction-adduction, flexion-extension, and internal-external rotation were calculated. The limb symmetry index (LSI) for quadriceps strength was calculated. Psychological readiness was measured using the Anterior Cruciate Ligament Return to Sport After Injury (ACL-RSI) scale. The paired t test analyzed the differences between contralateral and affected limbs in quadriceps and hamstrings strength. Pearson or Spearman correlation was used to assess relationships between the variables of interest. RESULTS: Significant differences between contralateral and affected limbs were observed in isokinetic knee quadriceps strength (P < 0.001) and hamstring strength (P = 0.009). The ACL-RSI score correlated negatively with interlimb differences in the knee flexion angle at IC (r = -0.35, P = 0.02) and ROM in the transverse plane (r = -0.41, P = 0.003). The LSI for quadriceps strength correlated negatively with the peak knee flexion angle (r = -0.37, P = 0.02) and positively with the ACL-RSI score (r = 0.3, P = 0.05). SIGNIFICANCE: Greater psychological readiness and quadriceps strength are associated with more symmetrical multiplanar knee kinematics. The improvement of these parameters may aid the recovery of knee kinematics after ACLR, and reduce the rate of reinjury and incidence of posttraumatic osteoarthritis.

Shikonin promotes rat periodontal bone defect repair and osteogenic differentiation of BMSCs by p38 MAPK pathway.

In recent years, the treatment of periodontal bone defect has been a major challenge. Cell-based bone tissue engineering provides an advanced way for bone regeneration. Bone formation hinges on the potential of osteogenesis in bone marrow stromal cells (BMSCs). Shikonin (SHI), an active principle of Radix Lithospermi, has shown a striking role to mitigate osteoporosis of ovariectomized mice, whereas its effects on periodontal bone defect are vague. Herein, we explored the impact of SHI on osteogenic differentiation of BMSCs in vitro and further analyzed the potential mechanisms using an inhibitor of p38 MAPK (SB203580). A rat periodontal bone defect model was built to assess its effects on bone formation in vivo by micro-CT and immunofluorescence. Our results showed SHI with no cytotoxicity could conspicuously enhanced alkaline phosphatase (ALP) activity, calcium accumulation and the expression of runt-related transcription factor 2 (Runx2) and osteocalcin (OCN) of BMSCs in vitro. Increased bone volume/tissue volume (BV/TV) and osteopontin (OPN) expression after SHI administration further demonstrated the capacity of promoting osteogenesis of SHI in vivo. Furthermore, SHI could also increase the phosphorylation of p38. However, the phosphorylation of p38 and expression of osteogenic indicators promoted by SHI were reversed by SB203580, thereby illustrating the positive regulatory relationship between p38 MAPK and SHI-mediated osteogenesis. This finding may help SHI become a promising agent with respect to the therapy of periodontal bone defect.

Epigallocatechin-3-gallate inhibits the formation of neutrophil extracellular traps and suppresses the migration and invasion of colon cancer cells by regulating STAT3/CXCL8 pathway.

Colon cancer is a common malignant tumor of the digestive tract. Tea catechin exerts anti-tumor effects in colon cancer. This work aimed to determine the functions of epigallocatechin-3-gallate (EGCG), one of the main active components of Tea catechins, in the progression of colon cancer. In this work, enzyme-linked immune-sorbent assay, quantitative real-time PCR and western blotting was utilized to examine the levels of IL-1ß, TNF-α, STAT3, p-STAT3 and CXCL8 in colon cancer patients and healthy controls. Compared with healthy controls, the levels of IL-1ß and TNF-α were significantly increased in the peripheral blood of colon cancer patients, and the expression of STAT3, p-STAT3 and CXCL8 was elevated in the neutrophils derived from colon cancer patients. Moreover, neutrophils were treated with phorbol ester (PMA) or DNase I to induce or impede the formation of neutrophil extracellular traps (NETs). Both STAT3 overexpression and PMA treatment promoted the expression of CXCL8, myeloperoxidase (MPO) and citrullinated histone H3 (H3Cit) in the colon cancer-derived neutrophils, indicating that STAT3 overexpression facilitated the formation of NETs. STAT3 deficiency suppressed the formation of NETs, which consistent with the results of DNase I treatment. Transwell assay was utilized to detect the migration and invasion of colon cancer cell line SW480. EGCG treatment suppressed the formation of NETs and the expression of STAT3 and CXCL8 in the colon cancer-derived neutrophils, and then inhibited the migration and invasion of SW480 cells. In conclusion, this work demonstrated that EGCG inhibited the formation of NETs and subsequent suppressed the migration and invasion of colon cancer cells by regulating STAT3/CXCL8 signalling pathway. Thus, this study suggests that EGCG may become a potential drug for colon cancer therapy.

The prognosis of TP53 and EGFR co-mutation in patients with advanced lung adenocarcinoma and intracranial metastasis treated with EGFR-TKIs.

Background: TP53 mutation is a poor factor for non-small cell lung cancer (NSCLC), while the effect of TP53 on prognosis in epidermal growth factor receptor (EGFR)-mutated lung adenocarcinoma (LUAD) with brain metastasis remains elusive and needs further exploration. Methods: We retrospectively analyzed 236 patients and tested for TP53- and EGFR-mutant status in metastasis LUAD patients who had received first-line EGFR-tyrosine kinase inhibitor (TKI) treatment. Survival rates were calculated by the Kaplan-Meier method. Furthermore, univariate and multivariate Cox analyses were performed to identify the independent prognostic factors. Results: There were 114 patients with confirmed non-brain metastasis (NBM), 74 patients with preliminary diagnosis early brain metastasis (EBM), and 48 patients with late brain metastasis (LBM). TP53 and EGFR co-mutations were found in 35/236 patients (14.8%). The median progression-free survival (PFS) and overall survival (OS) in the EGFR mutation and TP53 wild-type group were significantly longer than those in the EGFR and TP53 co-mutation group in all advanced LUAD or NBM. Concurrently, PFS and OS were found to be not significant in EBM and LBM patients. Subgroup analysis revealed longer median PFS and OS in the TP53 wild-type group compared to the TP53 mutant group in L858R patients and not significant in EGFR Exon 19 deletion patients. In LBM patients, the time to brain metastasis in the EGFR mutation and TP53 wild-type group was longer than that in the EGFR and TP53 co-mutation group, and TP53 mutant status was an independent prognostic factor for brain metastasis. The TP53 wild-type group exhibited a higher objective remission rate (ORR) and disease control rate (DCR) than the TP53 mutant group in NBM, EBM, and LBM patients, irrespective of primary lung and brain metastatic lesions. Conclusion: TP53/EGFR co-mutation patients receiving first-line EGFR-TKI treatment had poor prognoses in advanced LUAD, especially with L858R mutation. Moreover, TP53/EGFR co-mutation patients treated with EGFR-TKIs may more easy developed intracranial metastasis.

Multi-planar instability, laxity and reduced knee flexion during the support phase of walking are determinants of return to sports.

Background: After anterior cruciate ligament reconstruction, some patients are not recommended to return to high-level physical activity because they fail to pass return-to-sports tests. The kinematic difference between these patients and those who pass the return-to-sports tests is unclear. Methods: Eighty-two patients who received anatomic single-bundle anterior cruciate ligament (ACL) reconstruction for unilateral ACL injury underwent return-to-sport tests during a hospital visit at a minimum of 9 months (9-11 months) of follow-up. Fifteen patients who passed the return-to-sports tests (RTS group) and fifteen patients who did not (NRTS group) were randomly selected to perform a treadmill walk under dual-fluoroscopic imaging system surveillance for a 6 degrees of freedom kinematic evaluation. Results: Of the 82 patients, 53 passed the return-to-sports tests 9 months after surgery, with a return-to-sports rate of 64.6%. In the stance phase, the NRTS group had a larger anterior tibial translation (1.00 ± 0.03 mm vs. 0.76 ± 0.03 mm, p = 0.001), a larger lateral tibial movement (1.61 ± 0.05 mm vs. 0.77 ± 0.05 mm, p < 0.001), a larger distal tibial displacement (-3.09 ± 0.05 mm vs. -2.69 ± 0.05 mm, p < 0.001), a smaller knee flexion angle (6.72 ± 0.07° vs. 8.34 ± 0.07°, p < 0.001), a larger varus angle (-0.40 ± 0.03°VS. -0.01 ± 0.03°, p < 0.001) and a larger external rotation angle (1.80 ± 0.05° vs. 1.77 ± 0.05°, p < 0.001) than the RTS group. The maximum anterior tibial translation of the NRTS group is also larger than that of the RTS group (3.64 ± 0.42 mm vs. 3.03 ± 0.59 mm, p = 0.003). Conclusion: Compared with patients passing RTS tests, those who fail to pass show significant anterior, lateral, and rotational instability; knee laxity; and reduced flexion angle of the knee in the support phase during walking, which may be the possible factors hindering a return to sports.

Tumor microenvironment-related gene selenium-binding protein 1 (SELENBP1) is associated with immunotherapy efficacy and survival in colorectal cancer.

BACKGROUND: Selenium-binding protein 1 (SELENBP1), a member of the selenium-containing protein family, plays an important role in malignant tumorigenesis and progression. However, it is currently lacking research about relationship between SELENBP1 and immunotherapy in colorectal cancer (CRC). METHODS: We first analyzed the expression levels of SELENBP1 based on the Cancer Genome Atlas (TCGA), Oncomine andUALCAN. Chisq.test, Fisher.test, Wilcoxon-Mann-Whitney test and logistic regression were used to analyze the relationship of clinical characteristics with SELENBP1 expression. Then Gene ontology/ Kyoto encyclopedia of genes and genomes (GO/KEGG), Gene set enrichment analysis (GSEA) enrichment analysis to clarify bio-processes and signaling pathways. The cBioPortal was used to perform analysis of mutation sites, types, etc. of SELENBP1. In addition, the correlation of SELENBP1 gene with tumor immune infiltration and prognosis was analyzed using ssGSEA, ESTIMATE, tumor immune dysfunction and rejection (TIDE) algorithm and Kaplan-Meier (KM) Plotter database. Quantitative real-time PCR (qRT-PCR) and western blotting (WB) were used to validate the expression of SELENBP1 in CRC samples and matched normal tissues. Immunohistochemistry (IHC) was further performed to detect the expression of SELENBP1 in CRC samples and matched normal tissues. RESULTS: We found that SELENBP1 expression was lower in CRC compared to normal colorectal tissue and was associated with poor prognosis. The aggressiveness of CRC increased with decreased SELENBP1 expression. Enrichment analysis showed that the SELENBP1 gene was significantly enriched in several pathways, such as programmed death 1 (PD-1) signaling, signaling by interleukins, TCR signaling, collagen degradation, costimulation by the CD28 family. Decreased expression of SELENBP1 was associated with DNA methylation and mutation. Immune infiltration analysis identified that SELENBP1 expression was closely related to various immune cells and immune chemokines/receptors. With increasing SELENBP1 expression, immune and stromal components in the tumor microenvironment were significantly decreased. SELENBP1 expression in CRC patients affects patient prognosis by influencing tumor immune infiltration. Beside this, SELENBP1 expression is closely related to the sensitivity of chemotherapy and immunotherapy. CONCLUSIONS: Survival analysis as well as enrichment and immunoassay results suggest that SELENBP1 can be considered as a promising prognostic biomarker for CRC. SELENBP1 expression is closely associated with immune infiltration and immunotherapy. Collectively, our study provided useful information on the oncogenic role of SELENBP1, contributing to further exploring the underlying mechanisms.

Application of CRISPR/Cas9 System for Plasmid Elimination and Bacterial Killing of Bacillus cereus Group Strains.

The CRISPR-Cas system has been widely applied in prokaryotic genome editing with its high efficiency and easy operation. We constructed some "scissors plasmids" via using the temperature-sensitive pJOE8999 shuttle plasmid, which carry the different 20nt (N20) guiding the Cas9 nuclease as a scissors to break the target DNA. We successfully used scissors plasmids to eliminate native plasmids from Bacillus anthracis and Bacillus cereus, and specifically killed B. anthracis. When curing pXO1 and pXO2 virulence plasmids from B. anthracis A16PI2 and A16Q1, respectively, we found that the plasmid elimination percentage was slightly higher when the sgRNA targeted the replication initiation region (96-100%), rather than the non-replication initiation region (88-92%). We also tried using a mixture of two scissors plasmids to simultaneously eliminate pXO1 and pXO2 plasmids from B. anthracis, and the single and double plasmid-cured rates were 29 and 14%, respectively. To our surprise, when we used the scissor plasmid containing two tandem sgRNAs to cure the target plasmids pXO1 and pXO2 from wild strain B. anthracis A16 simultaneously, only the second sgRNA could guide Cas9 to cleave the target plasmid with high efficiency, while the first sgRNA didn't work in all the experiments we designed. When we used the CRISPR/cas9 system to eliminate the pCE1 mega-virulence plasmid from B. cereus BC307 by simply changing the sgRNA, we also obtained a plasmid-cured isogenic strain at a very high elimination rate (69%). The sterilization efficiency of B. anthracis was about 93%, which is similar to the efficiency of plasmid curing, and there was no significant difference in the efficiency of among the scissors plasmids containing single sgRNA, targeting multi-sites, or single-site targeting and the two tandem sgRNA. This simple and effective curing method, which is applicable to B. cereus group strains, provides a new way to study these bacteria and their virulence profiles.

Compact high-efficiency perfectly-vertical grating coupler on silicon at O-band.

A compact, high-efficiency grating coupler is demonstrated for interfacing a silicon waveguide and a perfectly-vertical fiber at O-band. The grating lies on a tilted silicon membrane for minimizing the reflections. Circular grating lines are adopted to shorten the overall device length to about 60µm. 57% peak coupling efficiency and >28nm 1-dB coupling bandwidth are obtained experimentally. Back reflections of 1% to the silicon waveguide and the single mode fiber are theoretically estimated. The processing flow to realize the proposed structure is discussed in detail. The fabrication control over the tilted angle of the silicon membrane is investigated. The approach by applying an oxide cladding to improve the stability of the membrane is also introduced. The present grating coupler is compatible to common fabrication processes for silicon photonic chips.

Metabolic Equivalents of Selected Sedentary and Physical Activities in Chinese Youth.

BACKGROUND: This study determined the metabolic equivalents (METs) of several activities typically performed by Chinese youth. METHODS: Thirty youth (12 years) performed 7 activities that reflected their daily activities while Energy Expenditure (EE) was measured in a metabolic chamber. RESULTS: METs were calculated as activity EE divided by participant's measured resting metabolic rate. A MET value ranging from 0.8 to 1.2 was obtained for sleeping, watching TV, playing computer games, reading and doing homework. Performing radio gymnastics had a MET value of 2.9. Jumping rope at low effort required 3.1 METs. Except for watching TV, METs for other activities in this study were lower than Youth Compendium values. CONCLUSIONS: The results provide empirical evidence for more accurately assessing EE of activities commonly performed by Chinese youth. This is the first study to determine METs for radio gymnastics and jump rope in Chinese youth.

Silicon waveguide grating coupler for perfectly vertical fiber based on a tilted membrane structure.

A grating coupler for interfacing between a silicon-on-insulator waveguide and a single-mode fiber located at a perfectly vertical direction is demonstrated based on a tilted membrane structure. The proposed design is compatible with that of conventional grating couplers for oblique fibers and facilitates mass production. A peak coupling efficiency of 28.5% and 1 dB bandwidth of 38 nm are obtained experimentally for transverse-electrics polarized light. Back reflection in the SOI waveguide is also estimated to be 1.4%. The present grating coupler for perfectly vertical fiber exhibits similar performances to the conventional grating coupler for oblique fiber concerning coupling efficiency, bandwidth, and back reflections.

Experimental demonstration of simultaneous mode and polarization-division multiplexing based on silicon densely packed waveguide array.

A silicon mode and polarization-division multiplexing scheme based on a densely packed waveguide array structured as a bus waveguide is introduced. A short adiabatic taper is adopted for (de)multiplexing. Such a structure shows theoretical insertion losses that are <0.05 dB and crosstalk that is <-20 dB over a wide wavelength band for all five supported modes. The structures for (de)multiplexing are fabricated and characterized experimentally. A device, which consists of a multiplexer, a 50-µm-long straight-bus waveguide, and a demultiplexer, exhibits insertion losses that are <0.6 dB and crosstalk that is <-15 dB over an 80 nm wavelength band. The demonstrated (de)multiplexer has a total length of 60 µm, and the bus waveguide has an effective width of 1.58 µm.