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Uniform air distribution is the basic condition for the stable operation of circulating fluidized beds and closely related to the hole layout of nozzles and the air outlet conditions. In this paper, CAD modeling software is used to establish different opening types for nozzles and the corresponding gasifier models, and Fluent simulation software for numerical simulations (k-ε model) is introduced to the hydrodynamic behavior of the upper opening, the side opening and the combined opening types of nozzles, as well as the corresponding single-nozzle fluidized bed gasifiers. The flow field distribution under the above opening modes is obtained, including the velocity distribution, static pressure distribution, and total pressure distribution, and the influence of the boundary conditions, including the inlet gas velocity and outlet pressure, on the flow field distribution inside the nozzle and in the single-nozzle fluidized bed gasifier is also investigated. The simulation results show that the suitable optimal operating conditions for the coal gasifier can be achieved with an inlet velocity of 30 m/s and an outlet pressure of 25 kPaG. Under the above conditions, the local fluidization dead zone at the elbow and top of the nozzle is narrower, the uniformity of the wind velocity can be improved, the pressure drop of the inner core tube of the nozzle is gentle, and the pressure distribution tends to be stable. Theoretically, the anti-slag performance of the nozzle is improved, which will enhance the stability and reliability of the operation of the gasification unit. [ABSTRACT FROM AUTHOR]

Background: Advances in regeneration methods have brought us improved vascular scaffolds with small diameters (φ < 6 mm) for enhancing biological suitability that solve their propensity for causing intimal hyperplasia post‐transplantation. Methods: The correlation between the rehydration ratio of the hydrogel and its material concentration is obtained by adjusting the material ratio of the hydrogel solution. The vascular model with helical structure has been established and analyzed to verify the effect of helical microvascular structure on thrombosis formation by the fluid simulation methods. Then, the helical structure vascular has been fabricated by self‐developed 3D bioprinter, the vascular scaffolds are freeze‐dried and rehydrated in polyethylene glycol (PEG) solution. Results: The experimental results showed that the hybrid hydrogel had a qualified rehydration ratio when the content of gelatin, sodium alginate, and glycerol was 5, 6, and 3 wt%. The established flow channel model can effectively reduce thrombus deposition and improve long‐term patency ratio. After PEG solution modification, the contact angle of the inner wall of the vascular scaffold was less than 30°, showing better hydrophilic characteristics. Conclusion: In study, a small‐diameter inner wall vascular scaffold with better long‐term patency was successfully designed and prepared by wrinkling and PEG modification of the inner wall of the vascular scaffold. This study not only creates small‐diameter vascular scaffolds with helical structure that improves the surface hydrophilicity to reduce the risk of thrombosis but also rekindles confidence in the regeneration of small caliber vascular structures. [ABSTRACT FROM AUTHOR]

Abstract Paeonia suffruticosa Andr. has a long history of cultivation in China and its flower possesses high nutritional and medicinal value. Characterization and macrophage immunomodulatory activity of the two polysaccharides from the flowers of Paeonia suffruticosa Andr., PSAP-1 and PSAP-2, purified by anion exchange chromatography followed by size exclusion chromatography, were investigated in the present study. Results showed that PSAP-1, with a molecular weight of 155 kDa, was mainly composed of glucuronic acid, glucose, arabinose and galactose with molar percentages of 0.83, 11.53, 18.98 and 68.96% respectively, and PSAP-2, with a molecular weight of 210 kDa, consisted of rhamnose, galacturonic acid, glucose, arabinose and galactose with molar percentages of 9.13, 8.35, 12.20, 14.75 and 55.57% respectively. Immunostimulatory activity evaluation in vitro revealed that the PSAP-1 and PSAP-2 could significantly stimulate the proliferation of Raw264.7 cells in dose-dependent manner and further activate Raw264.7 cells by releasing immunoactive molecules such as nitric oxide, tumor necrosis factor (TNF)-α and interleukin (IL)-6. In addition, PSAP-2 had higher immunomodulatory activity than PSAP-1. The above results suggested that both PSAP-1 and PSAP-2 had potent immunostimulatory activity and could be explored as a potential natural immunomodulatory agent in medicine or functional food fields. Highlights • Two polysaccharide fractions named PSAP-1 and PSAP-2 were prepared. • The chemical composition and molecular weight of PSAP-1 and PSAP-2 was characterized. • PSAP-1 and PSAP-2 showed potent macrophage immunomodulatory activity in vitro. [ABSTRACT FROM AUTHOR]

Abstract Graphene as a promising material for terahertz-infrared region plays an important role in nanoplasmonic devices owing to its tunability. We propose a hybrid graphene nanoplasmonic waveguide and analyze its propagation properties by finite element method. The results show that the light in terahertz-infrared region can be confined at low-index material and the fundamental mode can be tuned flexibly by changing Fermi energy level of graphene. Then an application of the designed waveguide, an electrically controllable directional coupler is designed and its performance is numerically verified. This approach can be extended to novel designs of nanoscale integrated photonic devices. [ABSTRACT FROM AUTHOR]