The exploitation of natural gas hydrates (NGHs) by traditional methods is far lower than the commercial target. Calcium oxide (CaO)-based in situ supplemental heat combined with depressurization is a novel method for effectively exploiting NGHs. In this study, we propose an in situ supplemental heat method with the sustained-release CaO-loaded microcapsules coated with polysaccharide film. The modified CaO-loaded microcapsules were coated with polysaccharide films using covalent layer-by-layer self-assembly and wet modification process, with (3-aminopropyl) trimethoxysilane as the coupling agent and modified cellulose and chitosan as the shell materials. Microstructural characterization and elemental analysis of the microcapsules verified the change in the surface composition during the fabrication process. We found that the overall particle size distribution was within the range of 1–100 μm, corresponding to the particle size distribution in the reservoir. Furthermore, the sustained-release microcapsules exhibit controllable exothermic behavior. The decomposition rates of the NGHs under the effect of CaO and CaO-loaded microcapsules coated with one and three layers of polysaccharide films were 36.2, 17.7, and 11.1 mmol h−1, respectively, while the exothermic time values were 0.16, 1.18, and 6.68 h, respectively. Finally, we propose an application method based on sustained-release CaO-loaded microcapsules used for the supplemental heat-based exploitation of NGHs.
Bo Zheng,Fengwei Xie,Wenbei Situ,Ling Chen,Xiaoxi Li
A new carrier system for controlled release of immunologic peptides based on double polysaccharide film-coated microparticles (PCMPs) used with liquid products was developed. The release behavior of PCMPs was shown dependent on the thicknesses of the outer chitosan film and the inner resistant starch acetate (RSA) film. The in-vitro release results indicated that, with optimized polysaccharide coating thickness (RSA: 4–5%; chitosan: 6–7%), the release rate of Thymopoietin (TP5) was less than 30% before the microparticles reached the colon, and was 50% in the colon. Besides, the bioavailability of PCMPs was evaluated based on the cell proliferation and protein expression. Compared with the intraperitoneal injection or oral administration, the immunodeficient rats that were orally administrated with the yogurt containing TP5-loaded PCMPs with different storage times possessed a good colon-targeting behavior, higher ratios of CD4/CD8 and IgG expression, indicating the improvement in the TP5 immunologic function.
The tubularlike three-dimensional tissue scaffold is an important architecture in biomedical engineering, but its construction remains a big challenge for existing techniques. This work reports the polysaccharide-biomaterial-based tubular microcapsule, which was fabricated by integrating a co-axial flow microfluidic chip and a polyelectrolyte complex technique. First, we fabricate the densely packed coiled calcium alginate hydrogel microfibers as the building block by a co-axial microfluid chip. Then, the densely packed coiled microfibers were coated with a multilayer membrane through layer-by-layer adsorption of alginate and chitosan. After that, the microfibers with an alginate–chitosan–alginate membrane were expanded and transformed into a tubular microcapsule structure by liquefaction. The tubular microcapsule exhibits a selectively permeable property of different-molecular-weight FITC-dextran/bovine serum albumin compared with original calcium alginate microfibers. Moreover, the tubular microcapsule with a liquefied lumen and a thin membrane allows the sustainable release of encapsulants under the alkaline environment. Our research paves an alternative way of manufacturing artificial biological tube architectures having potential applications for transporting and delivering drugs.
危险品化学品经营许可证（带存储）