No abstract

Various characteristics of dimethyl ether (DME) as an alternative fuel for compression ignition engines were experimentally investigated including its spray characteristics, combustion performance, and emission reduction in a common-rail diesel engine. The spray behavior of DME was analyzed in terms of injection rate, spray development, and spray tip penetration, which were measured by an injection rate meter and a high-pressure spray chamber equipped with a spray visualization system. In addition, the engine performance and indicated mean effective pressure (IMEP), as well as exhaust emissions, including oxides of nitrogen (NO x ), soot, hydrocarbons, and carbon monoxide were measured at various injection and operating cycle parameters. The combustion characteristics of DME fuel were compared with those of conventional diesel fuel in a diesel engine. Experimental results show that DME has an injection delay 0.03 ms shorter and a maximum injection rate 21% higher than those of diesel fuel at a constant injection pressure of 50 MPa and an injection mass of 8 mg/cycle. At a fixed energizing duration and injection pressure, a greater mass of DME was injected than that of diesel fuel. The DME-operated engine produced almost negligible soot emissions but also considerably higher NO x emissions than the engine operated with diesel fuel at a fixed IMEP.

No abstract

No abstract

A glucose-responsive closed-loop insulin delivery system represents an ideal form of treatment for type 1 diabetes mellitus. Here, we develop a glucose-responsive protein delivery system based on chitosan microgels loaded with enzymemimicking inorganic nanoparticles. The pH-sensitive chitosan microgels, integrated with glucose-mediated pH-lowering enzymatic large-pore mesoporous silica (MCF), were fabricated via an electrospray process. Ceria nanoparticles (CeNPs), which is a catalase-mimicking inorganic artificial enzyme with a substantial stability compared to that of catalase, were incorporated into the MCF along with glucose oxidase. In hyperglycemic conditions, CeNPs successfully decomposed the toxic hydrogen peroxide that was generated from the glucose oxidation reaction mediated by glucose oxidase and regenerate oxygen; this protected glucose oxidase from denaturation. The pH-lowering induced by the enzymatic MCF in high glucose concentration resulted in swelling of the chitosan microgels and the subsequent release of the encapsulated model protein drug, such as bovine serum albumin and insulin. Finally, we successfully demonstrated self-regulated repetitive protein release from the chitosan microgels, which showed a basal release rate under normoglycemic conditions and an enhanced release rate under hyperglycemic conditions.