All-silicon metalens for broadband achromatic polarization multiplexing in long-wave infrared wavelengths.

Traditional long-wave infrared polarimetry usually relies on complex optical setups, making it challenging to meet the increasing demand for system miniaturization. To address this problem, we design an all-silicon broadband achromatic polarization-multiplexing metalens (BAPM) operating at the wavelength range of 9-12 µm. A machine-learning-based design method is developed to replace the tedious and computationally intensive simulation of a large number of meta-atoms. The results indicate that the coefficients of variation in focal length of the BAPM are 3.95% and 3.71%, and the average focusing efficiencies are 41.3% and 40.5% under broadband light incidence with x- and y-polarizations, respectively.

Waveguide-integrated van der Waals heterostructure photodetector on a lithium niobate on insulator platform.

Lithium niobate (LN) photonics has gained significant interest for their distinct material properties. However, achieving monolithically integrated photodetectors on lithium niobate on an insulator (LNOI) platform for communication wavelengths remains a challenge due to the large bandgap and extremely low electrical conductivity of LN material. A two-dimensional (2D) material photodetector is an ideal solution for LNOI photonics with a strong light-matter interaction and simple integration technique. In this work, a van der Waals heterostructure photodiode composed of a p-type black phosphorus layer and an n-type MoS2 layer is successfully demonstrated for photodetection at communication wavelengths on a LNOI platform. The LNOI waveguide-integrated BP-MoS2 photodetector exhibits a dark current as low as 0.21 nA and an on/off ratio exceeding 200 under zero voltage bias with an incident power of 13.93 µW. A responsivity as high as 1.46 A/W is achieved at -1 V bias with a reasonable dark current around 2.33 µA. With the advantages of high responsivity, low dark current, and simple fabrication process, it is promising for the monolithically integrated photodetector application for LNOI photonic platforms at communication wavelengths.

Aluminum scandium nitride on 8-inch Si wafers: material characterization and photonic device demonstration.

The anisotropic optical properties of aluminum scandium nitride (Al1-xScxN) thin films for both ordinary and extraordinary light are investigated. A quantitative analysis of the band structures of the wurtzite Al1-xScxN is carried out. In addition, Al1-xScxN photonic waveguides and bends are fabricated on 8-inch Si substrates. With x = 0.087 and 0.181, the light propagation losses are 5.98 ± 0.11 dB/cm and 8.23 ± 0.39 dB/cm, and the 90° bending losses are 0.05 dB/turn and 0.08 dB/turn at 1550 nm wavelength, respectively.

Nanoimprinted TiO2 Metasurfaces with Reduced Meta-Atom Aspect Ratio and Enhanced Performance for Holographic Imaging.

Metasurface holograms, with the capability to manipulate spatial light amplitudes and phases, are considered next-generation solutions for holographic imaging. However, conventional fabrication approaches for meta-atoms are heavily dependent on electron-beam lithography (EBL), a technique known for its expensive and time-consuming nature. In this paper, a polarization-insensitive metasurface hologram is proposed using a cost-effective and rapid nanoimprinting method with titanium dioxide (TiO2) nanoparticle loaded polymer (NLP). Based on a simulation, it has been found that, despite a reduction in the aspect ratio of meta-atoms of nearly 20%, which is beneficial to silicon master etching, NLP filling, and the mold release processes, imaging efficiency can go up to 54% at wavelength of 532 nm. In addition, it demonstrates acceptable imaging quality at wavelengths of 473 and 671 nm. Moreover, the influence of fabrication errors and nanoimprinting material degradation in terms of residual layer thickness, meta-atom loss or fracture, thermal-induced dimensional variation, non-uniform distribution of TiO2 particles, etc., on the performance is investigated. The simulation results indicate that the proposed device exhibits a high tolerance to these defects, proving its applicability and robustness in practice.

Non-uniform distributed silicon optical phased array for high directionality and a wide steering range.

A non-uniform distributed silicon optical phased array (OPA) is proposed and numerically demonstrated to realize high directionality and a wide range for beam steering. The OPA is composed of grating antennas with dual-layer corrugations along silicon strip waveguides, which can achieve a high directionality of 0.96 and a small divergence angle of 0.084°. To reduce the crosstalk between adjacent antennas and realize a wide steering range, the genetic algorithm is improved and utilized to arrange the locations of grating antennas. As a proof of concept, a 32-channel non-uniform distributed OPA is designed and thoroughly optimized. The simulation results successfully demonstrate a two-dimensional wide steering range of 70∘×18.7∘ with a side-mode suppression ratio (SMSR) over 10 dB.

Tunable slow and fast light in a silicon-on-insulator Fano resonator.

Tunable slow and fast light generation in a silicon-on-insulator (SOI) Fano resonator is proposed and experimentally demonstrated. The slow and fast light generation with symmetric and asymmetric coupling conditions of the Fano resonator is theoretically analyzed. Under a slightly imbalanced coupling condition, the two output ports of the Fano resonator could produce a fast light and a slow light, respectively. By utilizing the thermo-optic (TO) effect to change the phase difference of the two optical beams coupled into the resonator, the transition of fast and slow light can be realized at the fixed resonance wavelength. Experimental results show that a slow-to-fast transition (group delay from 0.852 to -1.057 ns) at one resonance wavelength, and a fast-to-slow transition (group delay from -0.22 to 0.867 ns) at another resonance wavelength are realized simultaneously by controlling the microheater to tune the phase difference.

[Hesperidin Regulates Jagged1/Notch1 Pathway to Promote Macrophage Polarization and Alleviate Lung Injury in Mice with Bronchiolitis].

Objective To explore the effect and mechanism of hesperidin in treating the lung injury in the mouse model of respiratory syncytial virus (RSV)-induced bronchiolitis. Methods A mouse model of RSV-induced bronchiolitis was established,and 60 BALB/c mice were assigned into a control group,a model group,a low-dose hesperidin (18 mg/kg) group,a high-dose hesperidin (36 mg/kg) group,and a high-dose hesperidin (36 mg/kg)+Jagged1(1 mg/kg) group by random number table method,with 12 mice in each group. Corresponding doses of drugs were administrated for intervention,and the control group and model group were administrated with the same amount of saline.The bronchoalveolar lavage fluid (BALF) samples were collected and alveolar macrophages were isolated.ELISA was employed to detect the levels of interleukin (IL)-4,IL-6,tumor necrosis factor-α (TNF-α),and IL-10 in BALF,and flow cytometry to detect the M1/M2 polarization of macrophages.qRT-PCR and Western blotting were respectively conducted to detect the mRNA and protein levels of inducible nitric oxide synthase (iNOS),arginase 1 (Arg-1),Jagged1,and Notch1 in the lung tissue. Results Compared with the control group,the modeling of RSV-induced bronchiolitis elevated the IL-4,IL-6,and TNF-α levels,increased the proportion of M1-type macrophages and the lung inflammation and mucus secretion scores,and up-regulated the mRNA and protein levels of iNOS,Jagged1,and Notch1 in BALF (all P<0.001).Meanwhile,the modeling lowered the IL-10 level,decreased the proportion of M2-type macrophages,and down-regulated the mRNA and protein levels of Arg-1 (all P<0.001).Compared with the model group,low- and high-dose hesperidin lowered the IL-4,IL-6,TNF-α levels,decreased the proportion of M1-type macrophages and the lung inflammation and mucus secretion scores,and down-regulated the mRNA and protein levels of iNOS,Jagged1,and Notch1 in BALF (all P<0.05).Moreover,hesperidin elevated the IL-10 level,increased the proportion of M2-type macrophages,and up-regulated the mRNA and protein levels of Arg-1 (all P<0.001).Using recombinant Jagged1 protein to activate Notch1 signaling pathway can significantly attenuate the promotion of high-dose hesperidin on M2 macrophage polarization and amelioration of lung inflammation damage (all P<0.01). Conclusion Hesperidin may alleviate the lung inflammation damage in mice with RSV-induced bronchiolitis by inhibiting the Jagged1/Notch1 signaling pathway and promoting the M2-type polarization of macrophages.

[Features of intestinal flora in children with food protein-induced proctocolitis based on high-throughput sequencing]. / åŸºäºŽé«˜é€šé‡æµ‹åºæŠ€æœ¯åˆ†æžé£Ÿç‰©è›‹ç™½è¯±å¯¼æ€§ç›´è‚ ç»“è‚ ç‚Žæ‚£å„¿è‚ é“èŒç¾¤ç‰¹å¾.

OBJECTIVES: To study the features of intestinal flora in children with food protein-induced proctocolitis (FPIP) by high-throughput sequencing. METHODS: A total of 31 children, aged <6 months, who experienced FPIP after exclusive breastfeeding and attended the outpatient service of the Third Affiliated Hospital of Zunyi Medical University from October 2018 to February 2021 were enrolled as the FPIP group. Thirty-one healthy infants were enrolled as the control group. Fecal samples were collected to extract DNA for PCR amplification. High-throughput sequencing was used to perform a bioinformatics analysis of 16S rDNA V3-V4 fragments in fecal samples. RESULTS: The diversity analysis of intestinal flora showed that compared with the control group, the FPIP group had a lower Shannon index for diversity (P>0.05) and a significantly higher Chao index for abundance (P<0.01). At the phylum level, the intestinal flora in both groups were composed of Firmicutes, Actinobacteria, Proteobacteria, and Bacteroidetes. Compared with the control group, the FPIP group had a significant reduction in the composition ratio of Actinobacteria (P<0.001) and a significant increase in the composition ratio of Proteobacteria (P<0.05). At the genus level, the intestinal flora in the FPIP group were mainly composed of Escherichia, Clostridium, Enterococcus, Klebsiella, and Bifidobacterium, and the intestinal flora in the control group were mainly composed of Bifidobacterium and Streptococcus. Compared with the control group, the FPIP group had a significant reduction in the composition ratio of Bifidobacterium and Ruminococcus (P<0.05) and significant increases in the composition ratios of Clostridium and Shigella (P<0.05). CONCLUSIONS: Compared with the control group, the FPIP group has a reduction in the diversity of intestinal flora and an increase in their abundance, and there are certain differences in several bacterial genera. These results suggest that changes in the composition of intestinal flora at genus level may play an important role in the development and progression of FPIP.

Cryogenically probing the surface trap states of single nanowires passivated with self-assembled molecular monolayers.

Optoelectronically probing the trap state density of single nanoscale devices is a powerful in situ nondestructive technique that is of significance for developing high gain photoconductors by surface engineering. However, the previously demonstrated optoelectronic methods are based on the exponential transient photoresponse assumption and only trap states in a very narrow bandgap region can be probed. In this Letter, we demonstrate a cryogenic technique that is capable of measuring the density of surface trap states in the full half bandgap without the exponential transient photoresponse assumption. The technique is applied to an array of silicon nanowire photoconductors that are fabricated on silicon-on-insulator (SOI) wafer by the top-down approach. Diethyl 1-propylphosphonate (DPP) and hexadecane molecular monolayers are self-assembled on silicon nanowire surfaces as the passivation layer in comparison with dry oxide passivation. The surface trap state density of the dry oxide passivated nanowires exponentially increases from the bandgap center, reaching a peak of ∼5 × 1013 cm-2 eV-1 at 50 meV below the conduction band. The defect state density is significantly suppressed after DPP and hexadecane molecules are grafted onto the nanowire surfaces via covalent bonds. The experimental observations are consistent with the density functional theory calculations.

Electrospun homogeneous silk fibroin/poly (ɛ-caprolactone) nanofibrous scaffolds by addition of acetic acid for tissue engineering.

In this study, we investigated the phase separation phenomenon of silk fibroin/poly (ɛ-caprolactone) electrospinning solution to improve the performance of silk fibroin/poly (ɛ-caprolactone) electrospun nanofibers. It showed that phase separation does occur in just a few hours in the silk fibroin/poly (ɛ-caprolactone)/formic acid mixture solution. Acetic acid, small molecule nonsolvent for silk fibroin, was first introduced to silk fibroin/poly (ɛ-caprolactone)/formic acid solution, a homogeneous solution without separation for over several days was achieved after mixing for 5 h. The morphology and composition of the silk fibroin/poly (ɛ-caprolactone) and acetic acid-modified silk fibroin/poly (ɛ-caprolactone) fibrous scaffolds were examined by scanning electron microscopy, Fourier transform infrared spectroscopy and thermal gravimetric analyzer. Attachment and proliferation of mouse osteoblast MC3T3-E1 cells were tested by scanning electron microscopy and cytotoxity assay. The results indicated that the phase separation of silk fibroin/poly (ɛ-caprolactone) solution might led to inhomogeneous morphology and composition of the composite scaffolds, and the inhomogeneity of the silk fibroin/poly (ɛ-caprolactone) scaffolds with formic acid as solvent had a remarkable difference on cell adhesion and proliferation. In contrast, there was no significant difference among the silk fibroin/poly (ɛ-caprolactone) scaffolds with formic acid/acetic acid as solvent because of their good consistency in fiber morphology and composition. These obtained silk fibroin/poly (ɛ-caprolactone) nanofibers had small average diameter of 190 ± 40 nm. The obtained results proved that this study provided a facile and effective approach to achieve compositionally homogeneous silk fibroin/poly (ɛ-caprolactone) scaffolds with formic acid as solvent for effective applications.

Identification of Pseudomonas aeruginosa genes associated with antibiotic susceptibility.

Pseudomonas aeruginosa causes acute and chronic infections in humans and these infections are difficult to treat due to the bacteria's high-level of intrinsic and acquired resistance to antibiotics. To address this problem, it is crucial to investigate the molecular mechanisms of antibiotic resistance in this organism. In this study, a P. aeruginosa transposon insertion library of 17000 clones was constructed and screened for altered susceptibility to seven antibiotics. Colonies grown on agar plates containing antibiotics at minimum inhibitory concentrations (MICs) and those unable to grow at 1/2 MIC were collected. The transposon-disrupted genes in 43 confirmed mutants that showed at least a three-fold increase or a two-fold decrease in susceptibility to at least one antibiotic were determined by semi-random PCR and subsequent sequencing analysis. In addition to nine genes known to be associated with antibiotic resistance, including mexI, mexB and mexR, 24 new antibiotic resistance-associated genes were identified, including a fimbrial biogenesis gene pilY1 whose disruption resulted in a 128-fold increase in the MIC of carbenicillin. Twelve of the 43 genes identified were of unknown function. These genes could serve as targets to control or reverse antibiotic resistance in this important human pathogen.

[Screen and identification of genes involved in multidrug resistance in Pseudomonas aeruginosa].

OBJECTIVE: To identify genes involved in multidrug resistance in Pseudomonas aeruginosa. METHODS: We constructed and screened a transposon mutation library and obtained mutants that exhibited decreased drug resistance. The insertion sites of the transposon were identified by arbitrary PCR and subsequent DNA sequencing. RESULTS: Two mutants which became more susceptible to several antibacterial agents than the wild type were identified as mutants with transposon insertion in gene PA2580 and PA2800 respectively. The functions of these two genes are described as unknown in P. aeruginosa database. CONCLUSION: PA2580 and PA2800 are involved in drug resistance, possibly through their roles in redox reactions and cell envelope biogenesis.