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POSITIVE SOLUTIONS OF SINGULAR DIRICHLET PROBLEMS VIA VARIATIONAL METHODS
Sun, Juntao,Chu, Jifeng Korean Mathematical Society 2013 대한수학회지 Vol.50 No.4
In this paper, we establish the existence results for second order singular Dirichlet problems via variational methods. Some recent results are extended and improved. Examples are also given to illustrate the new results.
Positive solutions of singular Dirichlet problems via variational methods
Juntao Sun,Jifeng Chu 대한수학회 2013 대한수학회지 Vol.50 No.4
In this paper, we establish the existence results for secondorder singular Dirichlet problems via variational methods. Some recentresults are extended and improved. Examples are also given to illustratethe new results.
Production of Xylooligosaccharides from Corncobs Using Ultrasound-assisted Enzymatic Hydrolysis
Juntao Sun,Zhichao Zhang,Fugang Xiao,Ximei Jin 한국식품과학회 2015 Food Science and Biotechnology Vol.24 No.6
Xylooligosaccharides were obtained using ultrasound-assisted enzymatic hydrolysis from xylan that was alkali extracted from corncobs. Effects of alkali treatments on xylan extraction were investigated. The influence of operational conditions in ultrasound-assisted enzymatic hydrolysis on xylooligosaccharide production was also studied. Optimal conditions for xylan extraction were determined to be an alkaline concentration of 15%, a corncobs to alkaline solution ratio of 1:20, a reaction temperature of 100°C, and a reaction time of 2 h. Optimal conditions for xylanase-catalyzed hydrolysis of xylan to xylooligosaccharides were determined to be an enzyme concentration of 4 g/L, an ultrasound power of 200 W, a reaction temperature of 50°C and a reaction time of 10 min. Using a combination of ultrasound and enzyme increased the reducing sugar content by approximately 50%, compared with using of enzymes alone. Ultrasound and enzymes exert a synergistic effect.
Chunlei Wang,Juntao Yan,Jianfen Li,Jianmin Sun 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.9
A series of hierarchical mesoporous ZSM-5 zeolites with different morphology were successfully syn-thesized by the CO2-in-water microemulsion method, and mesoporosity was formed without organotemplate. The dif-ferent synthesis conditions, including silica alumina molar ratio, stirring time and compressed CO2 pressure, were sys-tematically investigated to discuss the influence of these conditions on the morphology of ZSM-5 zeolite. The resultingsamples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), inductively coupledplasma (ICP) and nitrogen adsorption-desorption measurement. XRD results indicated that compressed CO2 route forthe synthesis of MFI zeolites had a fast crystallization rate and good crystallinity. SEM images showed that the ZSM-5hierarchical mesoporous ZSM-5 zeolite had a uniform chain-like crystal morphology, whereas silicalite-1 displayed amonodisperse crystal morphology. In addition, the nitrogen adsorption-desorption measurement provided sufficientevidence for the presence of hierarchical mesopores in ZSM-5 zeolite.
Impact of Grafting Density on the Self-Assembly and Hydrophilicity of Succinylated Collagen
Wenxin Wang,Feiyi Shu,Lingyu Pan,Shanshan Huang,Xiao Tu,Ping Li,Siman Li,Yuanyuan Li,Chengzhi Xu,Yang Sun,Juntao Zhang,Haibo Wang 한국고분자학회 2020 Macromolecular Research Vol.28 No.6
Modification of protein could give their new functionality but would affect their intrinsic property and activity. In this paper, a series of succinylated collagen (SCol(n/1)) (n≥1) were prepared by modification of collagen with succinic anhydride at different molar ratio to amino groups amount of collagen. The impact of grafting density on the intrinsic self-assembly and additional hydrophilicity of succinylated collagen was explored. The results revealed that excessive grafting density of succinylated collagen would improve their hydrophilicity but weaken their self-assembly property, although the triple helix of collagen could be reserved after succinylation. SCol(1/1) (grafting density of 17%) with self-assembly property and good hydrophilicity was chosen to compare with native collagen. Compared to native collagen, thermostability of SCol(1/1) decreased slightly, however, SCol(1/1) could form softer hydrogel, which was more favorable for the proliferation of NIH/3 T3. The present work would help us to further understand the importance of grafting density for the design of modified collagen with intrinsic self-assembly property and additional new functionality.