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- 저자 : Gengsheng (검색결과 4 건)
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Model Based Filtered Backprojection Algorithm: A Tutorial
Gengsheng L. Zeng 대한의용생체공학회 2014 Biomedical Engineering Letters (BMEL) Vol.4 No.1
Purpose People have been wandering for a long timewhether a filtered backprojection (FBP) algorithm is able toincorporate measurement noise in image reconstruction. Thepurpose of this tutorial is to develop such an FBP algorithmthat is able to minimize an objective function with anembedded noise model. Methods An objective function is first set up to modelmeasurement noise and to enforce some constraints so thatthe resultant image has some pre-specified properties. Aniterative algorithm is used to minimize the objective function,and then the result of the iterative algorithm is converted intothe Fourier domain, which in turn leads to an FBP algorithm. The model based FBP algorithm is almost the same as theconventional FBP algorithm, except for the filtering step. Results The model based FBP algorithm has been applied tolow-dose x-ray CT, nuclear medicine, and real-time MRIapplications. Compared with the conventional FBP algorithm,the model based FBP algorithm is more effective in reducingnoise. Even though an iterative algorithm can achieve thesame noise-reducing performance, the model based FBPalgorithm is much more computationally efficient. Conclusions The model based FBP algorithm is an efficientand effective image reconstruction tool. In many applications,it can replace the state-of-the-art iterative algorithms, whichusually have a heavy computational cost. The model basedFBP algorithm is linear and it has advantages over a nonlineariterative algorithm in parametric image reconstruction andnoise analysis.
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Protein and polyphenols involved in sediment formation in cloudy litchi juice
Dan Zeng,Gengsheng Xiao,Yujuan Xu,Bo Zou,Jijun Wu,Yuanshan Yu 한국식품과학회 2019 Food Science and Biotechnology Vol.28 No.4
Sedimentation is a major issue in juice production. This paper aims to study the mechanisms of precipitateformation during the storage of cloudy litchi juice. Thesediment concentration, relative turbidity, and f potentialwere analyzed. The supernatant and sediment were separatedto determine the contents of proteins and phenolics. The results showed that the amount of sediment increasedduring the storage. In addition, the total protein and totalphenolic content in the supernatant decreased, whereas theglutelin and total phenolic contents in the sedimentincreased significantly (p\0.05). Moreover, our resultsshowed that the amounts of procyanidin B2 and quercetin-3-O-rutinose-7-O-rhamnoside in the supernatant decreasednoticeably. However, these two substances could not bedetected in the sediment. In summary, the formation ofsediment from litchi juice is mainly caused by the slowdenaturation of proteins and the oxidation of procyanidinB2 and quercetin-3-O-rutinose-7-O-rhamnoside.
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Xian Lin,Jinling Chen,Gengsheng Xiao,Yujuan Xu,Daobang Tang,Jijun Wu,Jing Wen,Weidong Chen 한국식품과학회 2016 Food Science and Biotechnology Vol.25 No.3
Ultrasonic-microwave synergistic extraction (UMSE) was optimized for the extraction of oligosaccharides from longan pulp (OLP). Box-Behnken design was used to evaluate the effects of temperature (35-55oC), ultrasonic time (5-25 min), and water to material ratio (10-30 mL/g) on the extraction efficiency of crude OLP. A regression model was developed and its validity was statistically demonstrated. Significant interaction between temperature and water to material ratio was observed. The following optimal conditions for the extraction yield of crude OLP were determined: extraction temperature 55oC, ultrasonic time 18.52 min, and water to material ratio 10 mL/g. The extracted OLP were purified for the determination of molecular weight distribution and antioxidant activity. Results of matrix-assisted laser desorption ionization time-of-flight mass spectrometry revealed that the molecular weight distribution of the purified OLP ranged from m/z 495.138 to 795.511. The purified OLP exhibited a dose-dependent behavior in 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity.
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Evolution of the antioxidant capacity and phenolic contents of persimmon during fermentation
Bo Zou,Jijun Wu,Yuanshan Yu,Gengsheng Xiao,Yujuan Xu 한국식품과학회 2017 Food Science and Biotechnology Vol.26 No.3
The changes in antioxidant capacity and phenolics of persimmon during alcoholic fermentation, acetification, and short aging were investigated. An increase in the antioxidant activity was observed when persimmon was transformed from puree to vinegar. The total content of phenolics remained stable, in contrast to the concentration of condensed tannin, which significantly (p\0.05) increased during alcoholic and acetic fermentations, although followed by a decrease after aging. The phenolic compounds were characterized and quantitated. Gallic acid was the main phenolic compound, and its content increased by 14.4% during alcoholic fermentation and reduced by 53.5% during acetic fermentation. Additionally, the flavan- 3-ol compounds increased during alcoholic fermentation and acetification. Vanillyl alcohol, (-)-epigallocatechin, and p-coumaric acid were not observed in persimmon puree but detected in persimmon wine and vinegar. These results indicate that alcoholic and acetic fermentation can improve the antioxidant capacity of persimmon fruit.
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