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Meiyu Zhang,Jaeyeong Choi,Da Wang,Lars Nilsson,Seungho Lee 한국분석과학회 2021 학술대회논문집 Vol.2021 No.11
Exudate gums are widely used as emulsifiers or thickening agents in the food industry. The performance of exudate gums is affected by their physicochemical properties such as molar mass (), molecular size, molecular conformation, protein content, et al. The high polydispersity, large and poor solubility of exudate gums bring challenges to their analysis. Either filtration or centrifugation can be used for preliminary separation of soluble and insoluble parts of the gum. However, their separation efficiency and their effect on the structural changes in gums are still unclear. In this research, asymmetrical flow field-flow fractionation coupled with multi-angle light scattering (AsFlFFF-MALS) was used to investigate the effect of the preparation method (filtration or centrifugation) on the size and the conformation of three types of gums (labelled ‘GT’, ‘GA’, and ‘GK’, respectively). The effect of removal of insoluble and large -populations on the emulsifying property of gums are also evaluated. Results showed that both filtration and centrifugation remove the co-eluted large populations, thus decrease the measured radius of gyration () of the gums. The removal of the large-sized populations and insoluble parts significantly reduced the viscosity of the gum dispersion and the emulsion prepared by the gums, resulting in an decreases in the stability of the emulsions.
Meiyu Zhang,Jaeyeong Choi,Da Wang,Lars Nilsson,Seungho Lee 한국분석과학회 2021 학술대회논문집 Vol.2021 No.11
Exudate gums are widely used as emulsifiers or thickening agents in the food industry. The performance of exudate gums is affected by their physicochemical properties such as molar mass (), molecular size, molecular conformation, protein content, et al. The high polydispersity, large and poor solubility of exudate gums bring challenges to their analysis. Either filtration or centrifugation can be used for preliminary separation of soluble and insoluble parts of the gum. However, their separation efficiency and their effect on the structural changes in gums are still unclear. In this research, asymmetrical flow field-flow fractionation coupled with multi-angle light scattering (AsFlFFF-MALS) was used to investigate the effect of the preparation method (filtration or centrifugation) on the size and the conformation of three types of gums (labelled ‘GT’, ‘GA’, and ‘GK’, respectively). The effect of removal of insoluble and large -populations on the emulsifying property of gums are also evaluated. Results showed that both filtration and centrifugation remove the co-eluted large populations, thus decrease the measured radius of gyration () of the gums. The removal of the large-sized populations and insoluble parts significantly reduced the viscosity of the gum dispersion and the emulsion prepared by the gums, resulting in an decreases in the stability of the emulsions.
Da Wang,Meiyu Zhang,Jae-Min Oh,Jaeyeong Choi,Seungho Lee 한국분석과학회 2021 학술대회논문집 Vol.2021 No.11
TiO₂ and SiO₂ nanoparticles are widely used as food additives. It has been reported that TiO₂ and SiO₂ nanoparticles as food additives may be toxic, possibly causing cancer or other diseases. It is thus necessary to develop effective methods for analysis of physical and chemical properties of TiO₂ and SiO₂ nanoparticles. Field-flow fractionation (FFF) is a family of analytical tool for separation and characterization of polydispersed nanoparticles. Among the FFF family members, sedimentation field-flow fractionation (SdFFF) is suitable for analyzing nanoparticles based on their sizes and/or densities. In this study, SdFFF was setup, and was used to perform separation and quantitative analysis of TiO₂ and SiO₂ nanoparticles after mixing with food matrices such as sucrose or casein. This study focuses on quantitative analysis of the nanoparticles mixed in food matrix, and, to some extent, the size change of the nanoparticles in food matrix. Results show that sucrose promotes aggregation of TiO₂, resulting in an increase in the size of TiO₂ nanoparticles. Casein has essentially no effect on the dispersing of SiO₂ nanoparticles. This study demonstrates that SdFFF is a useful and reliable method for separation and quantitation of food-grade nanoparticles.
Da Wang,Meiyu Zhang,Jae-Min Oh,Jaeyeong Choi,Seungho Lee 한국분석과학회 2021 학술대회논문집 Vol.2021 No.11
TiO₂ and SiO₂ nanoparticles are widely used as food additives. It has been reported that TiO₂ and SiO₂ nanoparticles as food additives may be toxic, possibly causing cancer or other diseases. It is thus necessary to develop effective methods for analysis of physical and chemical properties of TiO₂ and SiO₂ nanoparticles. Field-flow fractionation (FFF) is a family of analytical tool for separation and characterization of polydispersed nanoparticles. Among the FFF family members, sedimentation field-flow fractionation (SdFFF) is suitable for analyzing nanoparticles based on their sizes and/or densities. In this study, SdFFF was setup, and was used to perform separation and quantitative analysis of TiO₂ and SiO₂ nanoparticles after mixing with food matrices such as sucrose or casein. This study focuses on quantitative analysis of the nanoparticles mixed in food matrix, and, to some extent, the size change of the nanoparticles in food matrix. Results show that sucrose promotes aggregation of TiO₂, resulting in an increase in the size of TiO₂ nanoparticles. Casein has essentially no effect on the dispersing of SiO₂ nanoparticles. This study demonstrates that SdFFF is a useful and reliable method for separation and quantitation of food-grade nanoparticles.
Zhong Wang,Xiao-Hong Jiao,Meiyu Feng 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.4
During sandblasting and spray painting for hull, the tracking performance of the end-effector of manipulator to the outer surface of the hull in uniform velocity is seriously affected by uncertainty of the electrohydraulic actuator and deflection of the manipulator. To effectively improve the tracking performance of the tipposition/ velocity, a novel tracking control strategy is proposed, which is based on active disturbance rejection control (ADRC) with extended state observer (ESO) and setting position feedforward control with deflection compensation. First, to reduce tracking error caused by the deflection, the reference positions of two cylinders driving telescopic and luffing motion are calculated with consideration of the deflection influence according to manipulator geometry. And then, ADRC technique is adopted to design the position servo controller of the luffing/telescopic cylinder with the help of the estimate for the uncertainty of the electro-hydraulic system by the ESO. The stability of the whole closed-loop system and the convergence of tracking error are guaranteed theoretically, simultaneously, simulation carried out in Matlab/Simulink environment with physical parameters of a real system demonstrates the effectiveness and superiority of the proposed control strategy compared with existing control schemes. Furthermore, the experimental result is given to show the feasibility and availability of the control method.
Binnam Kang,Meiyu Zhang,Da Wang,Jaeyeong Choi,Seungho Lee 한국분석과학회 2021 학술대회논문집 Vol.2021 No.11
Lipid vesicle (LV) is widely used for drug delivery due to its low toxicity, its structure being similar to the cell membrane of the human body, and its capability to carry substances inside the hollow structure. LVs are classified as multilamellar vesicle (MLV) and unilamellar vesicle (ULV) according to the number of lipid bilayers. The lamellarity affects the size distribution and stability of the LVs as well as the encapsulation efficiency and the drug releasing kinetics. It is thus necessary to develop a methodology for identifying the lamellarity of LVs. In this study, LVs of various sized were prepared, and then asymmetric flow field-flow fractionation coupled with a multi-angle light scattering (AsFlFFF-MALS) was used to measure their molar masses. The molar masses were compared with those calculated from the size of the lipid vesicles to determine the LV lamellarity. Results showed that the LV size decreased as the extrusion flow rate increased. And the LV lamellarity is affected by the extrusion flow rate and the lipid concentration. Under the influence of osmotic pressure, the size distribution of LVs tends to decrease in the case of hypotonicity and increase in the case of hypertonicity. The AsFlFFF-MALS provided a useful tool for determining the lamellarity of LVs. This method may be useful for quality control of LVs in the fields such as drug delivery applications.
Miyeon Park,Meiyu Zhang,Da Wang,Jaeyeong Choi,Seungho Lee 한국분석과학회 2021 학술대회논문집 Vol.2021 No.11
Solid lipid nanoparticles (SLNs) have a particle structure in which a surfactant surrounds a lipid-containing material such as drug or cosmetics. SLNs have some merits that they can be mass-produced in a short period of time and that they can be used as a colloidal carrier in various types of products including cosmetics. It can carry ingredients such as UV filters, improving chemical and physical storage stability, and improving skin occlusion. Studies have shown that the UV protection effectiveness of UV filters encapsulated in SLN is affected by the size of SLNs. In this study, SLNs of various sizes were prepared by controlling the composition of lipid, surfactant, and UV filter. Then, the sizes of SLNs were characterized by using asymmetrical flow field-flow fractionation coupled with a photodiode array detector (AsFlFFF-PDA). The AsFlFFF conditions were optimized with the channel flow rate of 1.0 mL/min, cross-flow rate of 4.0 mL/min, and the composition of the carrier liquid of water containing 0.02% NaN₃. Results showed that the SLNs size increases with increasing lipid concentration and decreasing surfactant concentration. Sunscreen formations were prepared using the SLNs, and the sun protection factor (SPF), a UV protection index, was measured. The SPF tends to increase as the size of SLN decreases. However, the SPF values were relatively low, probably due to prolonged homogenization process during the SLN preparation. It is suggested to shorten the homogenization time.
Effect of 3C-SiC Intermediate Layer in GaN-Based Light Emitting Diodes Grown on Si(111) Substrate
Youhua Zhu,Meiyu Wang,Yi Li,Shuxin Tan,Honghai Deng,Xinglong Guo,Haihong Yin,Takashi Egawa 대한금속·재료학회 2017 ELECTRONIC MATERIALS LETTERS Vol.13 No.2
GaN-based light emitting diodes (LEDs) have been grown by metalorganicchemical vapor deposition on Si(111) substrate with and without3C-SiC intermediate layer (IL). Structural property has been characterizedby means of atomic force microscope, X-ray diffraction, andtransmission electron microscope measurements. It has been revealedthat a significant improvement in crystalline quality of GaN and superlatticeepitaxial layers can be achieved by using 3C-SiC as IL. Regardingof electrical and optical characteristics, it is clearly observed that theLEDs with its IL have a smaller leakage current and higher light outputpower comparing with the LEDs without IL. The better performance ofLEDs using 3C-SiC IL can be contributed to both of the improvementsin epitaxial layers quality and light extraction efficiency. As aconsequence, in terms of optical property, a double enhancement of thelight output power and external quantum efficiency has been realized.