High-purity orbital angular momentum vortex beam generator using an amplitude-and-phase metasurface.

In this Letter, we propose an approach to generate high-purity orbital angular momentum (OAM) vortex waves using an amplitude-and-phase metasurface (APM). By varying the square split ring opening and orientation angles, the cross-polarized reflection response of the proposed structure can yield full phase and amplitude coverage. Based on the traditional phase-only metasurface (POM), the Chebyshev synthesis method (CSM) is applied to array the metasurface amplitude distribution. Metasurfaces with modes l of 1, 2, 3, and 4 are designed. Compared with the POM, the APM can effectively improve the vortex beam quality and OAM mode purity. The measured results agree well with full-wave simulations. The presented method provides a new, to the best of our knowledge, way to design high-purity OAM generators based on metasurfaces.

Computational Modeling of Boundary Layer Flashback in a Swirling Stratified Flame Using a LES-Based Non-Adiabatic Tabulated Chemistry Approach.

When operating under lean fuel-air conditions, flame flashback is an operational safety issue in stationary gas turbines. In particular, with the increased use of hydrogen, the propagation of the flame through the boundary layers into the mixing section becomes feasible. Typically, these mixing regions are not designed to hold a high-temperature flame and can lead to catastrophic failure of the gas turbine. Flame flashback along the boundary layers is a competition between chemical reactions in a turbulent flow, where fuel and air are incompletely mixed, and heat loss to the wall that promotes flame quenching. The focus of this work is to develop a comprehensive simulation approach to model boundary layer flashback, accounting for fuel-air stratification and wall heat loss. A large eddy simulation (LES) based framework is used, along with a tabulation-based combustion model. Different approaches to tabulation and the effect of wall heat loss are studied. An experimental flashback configuration is used to understand the predictive accuracy of the models. It is shown that diffusion-flame-based tabulation methods are better suited due to the flashback occurring in relatively low-strain and lean fuel-air mixtures. Further, the flashback is promoted by the formation of features such as flame tongues, which induce negative velocity separated boundary layer flow that promotes upstream flame motion. The wall heat loss alters the strength of these separated flows, which in turn affects the flashback propensity. Comparisons with experimental data for both non-reacting cases that quantify fuel-air mixing and reacting flashback cases are used to demonstrate predictive accuracy.

Recent Advances in Fire-Retardant Silicone Rubber Composites.

Silicone rubber (SR), as one kind of highly valuable rubber material, has been widely used in many fields, e.g., construction, transportation, the electronics industry, automobiles, aviation, and biology, owing to its attractive properties, including high- and low-temperature resistance, weathering resistance, chemical stability, and electrical isolation, as well as transparency. Unfortunately, the inherent flammability of SR largely restricts its practical application in many fields that have high standard requirements for flame retardancy. Throughout the last decade, a series of flame-retardant strategies have been adopted which enhance the flame retardancy of SR and even enhance its other key properties, such as mechanical properties and thermal stability. This comprehensive review systematically reviewed the recent research advances in flame-retarded SR materials and summarized and introduced the up-to-date design of different types of flame retardants and their effects on flame-retardant properties and other performances of SR. In addition, the related flame-retardant mechanisms of the as-prepared flame-retardant SR materials are analyzed and presented. Moreover, key challenges associated with these various types of FRs are discussed, and future development directions are also proposed.

Enhanced Mechanical and Corrosion Properties via Annealing Treatment on the Hot-Rolled Ti-Zr-Mo Alloy.

In this work, the Ti-20Zr-15Mo alloy in its hot-rolled state was annealed in different phase zones, and the effects of the annealing treatment on the phase composition, organization, mechanical and corrosion resistance properties of the alloy were systematically investigated. The results showed that the original ß grains of the alloy had all recrystallized to form the ß equiaxial grains when annealed at 800 °C, and the grains had been significantly refined. This allowed the alloy to reach a tensile strength of 1000 MPa, a maximum of 28% after stretching, and a significant increase in plasticity. Also, due to the single beta phase, there was no galvanic corrosion, making the alloy annealed at 800 °C have the best corrosion resistance.

[Preventive and therapeutic effects of safflower water extract on systemic scleroderma in mice and its mechanism].

OBJECTIVE: To study the preventive and therapeutic effects of safflower water extract on systemic scleroderma (SSc) in mice and its mechanism. METHODS: Sixty BALB/C mice were randomly divided into the control group, model group, prednisone group and safflower low, middle, high dose groups, 10 mice in each group.The control group was injected with normal saline, and the other five groups were subcutaneously injected with bleomycin hydrochloride with 100 µl at the concentration of 200 µg /ml on the back, once a day for 28 days to establish the SSc models.At the same time, the control group and model group were treated with normal saline (10 ml/kg), the prednisone group was treated with prednisone 4.5 mg/kg (10 ml/kg), and the low, middle, and high dose safflower groups were treated with safflower at the doses of 1.5, 3, 6 g/kg (10 ml/kg), and all groups were treated for 28 days.After 28 days, all mice were decapitated. The blood samples and back skin of the BLM injection part were collected.After that, all the tissue slices were taken to measure the dermal thickness, and the content of hydroxyproline (HYP) in the skin tissues was detected by hydrolysis method.The contents of tissue growth factor (CTGF) and transforming growth factor-ß (TGF-ß ) in the skin tissues and the levels of interleukin-6 (IL-6) and interleukin-17 (IL-17) in serum were determined by ELISA. RESULTS: Compared with the control group, the dermal thickness of the model group was increased(P＜0.05), the contents of CTGF, TGF-ß and HYP in the skin tissues and the levels of IL-6 and IL-17 in the serum of the model group were increased(P＜0.05); compared with the model group, the dermal thickness in the prednisone group and safflower groups was decreased (P＜0.05), the levels of CTGF, TGF-ß and HYP in the skin tissues and the serum levels of IL-6 and IL-17 in the prednisone group and safflower groups were decreased (P＜0.05). CONCLUSION: Safflower water extract can improve skin condition (or dermal thickness) in SSc mice, and its mechanism may be related to reducing immune inflammatory response.

[Protective effects of azithromycin on adriamycin-induced nephropathy with albumin overload in mice].

OBJECTIVE: To study the protective effects of azithromycin on renal damage induced by doxorubicin and albumin in mice. METHODS: Forty male BALB/c mice were randomly divided into blank control group (Ctrl group), renal damage model group (ADR+BSA group), azithromycin treated group (Azm group) and prednisone acetate positive control group (Pdn group) in accordance with random number table method. Mice in ADR+BSA, AZM and Pdn group were injected intravenously with 9.8 kg-1 doxorubicin five days a week, 10 kg-1 serum albumin was injected intraperitoneally, and normal saline was administered to the control group for 4 weeks to establish renal damage model. After that, AZM group was given daily. 62.5 kg-1 azithromycin was intragastrically administered. The Pdn group was given 12.5 kg-1 prednisone acetate daily, the other two groups were given the same amount of normal saline. After 6 weeks, the urine volume was collected and recorded for 24 hours to detected urine protein amount and endogenous creatinine clearance rate (Ccr). Serum biochemical indicators and serum immune factors were detected. RESULTS: Compared with the Ctrl group, the 24 h urine protein level of the ADR+BSA group was increased significantly (P＜0.05), and the Ccr was decreased significantly (P＜0.05). After the azithromycin treatment, the 24 h urine protein was decreased significantly (P＜0.05), while the Ccr was increased significantly (P＜0.05) compared with ADR+BSA group. CONCLUSION: Azithromycin has a protective effects on the renal damage induced by doxorubicin and albumin in mice.