Yuanbao Jin

Simulation study on combustion of biomass

Biomass combustion is the most common energy conversion technology, offering the advantages of low cost, low risk and high efficiency. In this paper, the transformation and transfer of biomass in the process of combustion are discussed in detail. The process of furnace combustion and gas phase formation was analyzed by numerical simulation. The experimental results not only help to optimize boiler operation and realize the efficient combustion of biomass, but also provide theoretical basis for the improvement of burner technology.

37 Optimization of supercritical carbon dioxide extraction conditions of Semen cassiae volatile oil using response surface methodology and antimicrobial activity detection

Objectives The objective of this project was to study the process of extracting Semen cassia. The volatile components of Semen cassia were analyzed using supercritical CO2 extraction (SCDE). Based on a single factor experiment, response surface methodology was used to investigate the extraction of volatile oil. According to the fitted curves under different conditions, the effects of pressure, temperature and time on extraction and interactions between various factors were determined. Antimicrobial activity was also measured. Methods A Box-Behnken central composite design method was used based on single factor experiments. The influence of extraction temperature, extraction time and extraction pressure on extraction yield was studied. The response surface method was employed to analyze the results of experiments. The disk diffusion method was used to detect the antimicrobial activity of Semen cassiae volatile oil. Results The results indicated that the optimum extraction conditions were as follows: extraction temperature 51°C, extraction time 3.22 hours and extraction pressure 25 MPa. Extraction yield reached 2.34%. The volatile oil of Semen cassiae extracted from the tested strains showed antimicrobial activity, with MIC values ranging from 2.5 to 5 mg/mL.Abstract 37 Figure 1 Responsive surfaces and contours Conclusions SCDE is a stable and efficient process. Semen cassiae volatile oil had antimicrobial activity which could provide a theoretical basis for application of this oil.

46 Sandwich-type ethylcellulose films for controlled release of anti-restenosis drugs

Objectives Restenosis is a response of the vessel wall to balloon-induced injury and is characterized primarily by elastic recoil of the vessel wall and a series of pathological processes including thrombus, inflammation and vascular smooth muscle cell (VSMC) proliferation. To treat restenosis, appropriate drug delivery vehicles are needed which can release therapeutic agents targeting different symptoms into blood vessels in a controlled manner. The main objective of the present study was to prepare sandwich-type ethyl cellulose films with high performance for efficient drug loading and controlled drug release for restenosis treatment. Methods Sandwich-type ethyl cellulose films loaded with probucol for treating coronary artery disease, or aspirin as an antithrombotic drug, were prepared by casting three individual layers in sequence using an ethyl cellulose/toluene solution. On a glass plate, the first ethyl cellulose layer (bottom layer) was cast without drugs, on to which the middle layer containing probucol or aspirin was then cast. After solvent evaporation at room temperature, a third top layer was cast on to the middle layer. The obtained drug-loading films were further dried at room temperature under vacuum. Results The sandwich-type ethyl cellulose films exhibited a drug loading content (DLC) of 12.1 ± 0.9% and a drug loading efficiency (DLE) of 73.5 ± 3.6% for aspirin, and a DLC of 11.0 ± 0.8% and a DLE of 69.3 ± 3.4% for probucol. Under physiological conditions (37°C, pH 7.4), the release half-life of aspirin from the films was 2.7 ± 0.2 hours, while that of probucol was 7.1 ± 0.6 days. The two drugs showed totally different release behaviors, which can be employed in combination to treat restenosis. Conclusion Sandwich-type ethylcellulose films loaded with probucol or aspirin were successfully prepared and showed ability to release the two drugs in different ways: rapid release of aspirin to treat thrombus and inflammation typical of early-stage restenosis, and sustained release of probucol for inhibition of VSMC proliferation frequently seen in the later stage of restenosis. These drug-loaded ethylcellulose films provide new insight into restenosis therapy.

36 Study on the taste-masking performance of mesoporous molecular sieves

Objectives Patient medication compliance can be seriously affected by a bitter taste. There are various taste-masking agents, but they urgently need to be improved. Mesoporous molecular sieves are a type of 3-dimensional nanostructure that has a regular pore diameter (2–50 nm), has a large surface area, and is non-toxic. These structures are widely used in biomedicine but their application in the drug taste-masking field has not previously been reported. The objective of this investigation was to prepare three different mesoporous molecular sieves (MCM-41, MCM-48 and HMSS) and to determine their masking properties through volunteer tasting. Methods MCM-41, MCM-48 and HMSS were synthesized using a hydrothermal method. The bitter-tasting drug cetirizine (CTH) was used as the model drug. CTH-sieve composites were prepared using the impregnation method and the composites were characterized by means of XRD, FTIR, nitrogen physical adsorption and TGA. Three commonly used taste-masking agents were used as contrast to mask the bitter flavor of CTH. Results MCM-41, MCM48 and HMSS showed a large CTH loading capacity of 25.12%, 32.91% and 50.00%, respectively, and effectively reduced the bitter taste of CTH by covering the oral mucous membrane thus reducing irritation. Conclusions The pore structure and large surface area of the sieves improved taste-masking efficiency compared with common taste-masking agents. Mesoporous molecular sieves have the potential to increase the efficacy of taste-masking agents. Acknowledgments This research was financially supported by Jilin Provincial Development and Reform Commission Industrial Technology Research and Development Funds (Grant No. 2014Y091).

44 Core-shell nanospheres for pH-responsive release of anticancer drugs and near-infrared imaging

Objectives Nanoscaled drug carriers with pH-responsiveness have attracted extensive interest in view of the acidic environment in cancerous cells. Rapid response to pH changes plays a key role in efficient intracellular drug release. In addition, real-time tracking of drug carriers is important for understanding distribution and targeted accumulation of the drug carriers. This work aims at developing silver selenide quantum dots (Ag2Se QDs)@carboxymethyl chitosan (CMCS) core-shell nanospheres with encapsulated paclitaxel (PTX) for cancer therapy and bioimaging. Methods Oleic acid-capping Ag2 Se QDs were synthesized by a one-pot strategy, washed with ethanol, and obtained by centrifugation. The as-synthesized Ag2Se QDs were reacted with N-hydroxysuccinimide and conjugated with CMCS at the amino sites. In an aqueous solution of PTX, the hydrophobic oleoyl groups tended to aggregate locally and entrap PTX by hydrophobic interaction, spontaneously producing Ag2Se QDs (PTX)@CMCS nanospheres. Results By conjugating the oleic acid-capping Ag2 Se QDs with pH-sensitive CMCS at a degree of substitution (DS) of 13%, biocompatible core-shell nanospheres loaded with PTX were successfully prepared, which had an average size of 36.3 ± 0.2 nm. The drug loading content (DLC) and drug loading efficiency (DLE) for the PTX was 5.01 ± 0.8% and 52.4 ± 3.2%, respectively. The PTX release half-life was 4.1 hours under conditions resembling the intracellular environment of cancerous cells (37°C, pH 5.0). Conclusions Core-shell structured Ag2Se QDs (PTX)@CMCS nanospheres capable of releasing PTX in an acidic environment and emitting NIR fluorescence under NIR laser excitation were synthesized and characterized. The hydrophobic oleoyl groups entrapped PTX via hydrophobic interaction and the oleoyl-CMCS chains were extended at lowered pH to release the otherwise encaged drug. In addition, the encapsulated Ag2Se QDs can emit bright NIR fluorescence for bioimaging by which nanosphere distribution in a patient can be monitored. This study provides a new approach for developing nanocomposite drug carriers for cancer therapy.