Characteristics of the Blockage from Air Nozzle Guide Duct in Circulating the Fluidized-Bed Coal Gasifier and Its Formation Mechanism.

Blockage is often generated in the air nozzle guide duct in a circulating fluidized-bed coal gasifier (CFBG), especially with Zhundong sub-bituminous coal (ZSBC) as the raw material. A typical example is found in one CFBG sample from Xinjiang Yihua Chemical Industry Co, Ltd. The serious blockage can be observed obviously. As so far, it is not clear for the characteristics and generation mechanism of the blockage. For analysis, the blockage can be classified into two parts, wall-layer blockage (WLB) and center-layer blockage (CLB). To inhibit its formation, it is of significance to analyze the composition, surface morphology, and formation mechanism of the two blockages. In our experiments, WLB and CLB were tested by XRF, XRD, FTIR, SEM-EDS, and SEM-mapping methods. Results showed that WLB presents high content of Fe, Cr, and Ni, and Fe mainly existed in the form of metal oxides. CLB is dominated by Si (43.04%), derived from silica and alkali and alkaline-earth metals silicates, and the migration of Fe, Cr, and Ni elements from the duct material was observed. Compared with WLB, from FTIR analysis, CLB contains more inorganic minerals, and the absorption peak of inorganic minerals is mainly attributed to asymmetric Si-O-Si. Many fine particles are attached to the surface of the WLB, while the surface of the CLB is smooth, and there is noticeable raised texture, which is presumed to be the result of particle melting and agglomerating as the bottom ash enters the duct in the gasification process. For the formation of the blockage, this paper speculates that it is mainly due to the difference in flow resistance near the air nozzle outlet, resulting in the formation of a flow dead zone at the bottom of the gasifier, which leads to large amounts of ash overcoming the outlet resistance and leaking into the air nozzle, and next, the ash corrodes in the tube, resulting in wall deposition and ultimately blocking the air guide duct. Two methods can be tried to avoid or inhibit the formation of blockage in the duct, including optimizing air nozzle with more wear-resistant and heat-resistant materials and adjusting the distance between air nozzles to avoid mutual interference from ash particles.

Design and preparation of an artificial vascular scaffold with internal surface modification.

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.

Characterization and macrophage immunomodulatory activity of two polysaccharides from the flowers of Paeonia suffruticosa Andr.

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.