The isolation of minor components from complex natural product matrices presents a significant challenge in the field of purification science due to their low concentrations and the presence of structurally similar co...The isolation of minor components from complex natural product matrices presents a significant challenge in the field of purification science due to their low concentrations and the presence of structurally similar compounds.This study introduces an optimized twin-column recycling chromatography method for the efficient and simultaneous purification of these elusive constituents.By introducing water at a small flowing rate between the twin columns,a step solvent gradient is created,by which the leading edge of concentration band would migrate at a slower rate than the trailing edge as it flowing from the upstream to downstream column.Hence,the band broadening is counterbalanced,resulting in an enrichment effect for those minor components in separation process.Herein,two target substances,which showed similar peak position in high performance liquid chromatography(HPLC)and did not exceed 1.8%in crude paclitaxel were selected as target compounds for separation.By using the twin-column recycling chromatography with a step solvent gradient,a successful purification was achieved in getting the two with the purity almost 100%.We suggest this method is suitable for the separation of most components in natural produces,which shows higher precision and recovery rate compared with the common lab-operated separation ways for natural products(thin-layer chromatography and prep-HPLC).展开更多
Macadamia is rich in lipids and considered as a source of high-quality oil. In this study, fatty acids, triacylglycerols, minor components and antioxidant activities of macadamia oils (MOs) from four cultivated region...Macadamia is rich in lipids and considered as a source of high-quality oil. In this study, fatty acids, triacylglycerols, minor components and antioxidant activities of macadamia oils (MOs) from four cultivated regions (YN: Yunnan Province;GZ: Guizhou Province;GX: Guangxi Province;GD: Guangdong Province) in China were systematically analyzed by modern chromatography (Gas chromatography, high performance liquid chromatography, inductively coupled plasma mass spectrometry and ultraviolet spectroscopy). The analysis indicated macadamia oil enriched in unsaturated fatty acids (UFA), including 62.4%–65.6% oleic acid and 11.4%–17.3% palmitoleic acid. Among the four cultivated regions, the MO from YN exhibited the highest contents of UFA (85.0%) and palmitoleic acid. In addition, the minor components and antioxidant activities of MO from four cultivation areas showed a significant difference, which GX-MO had the highest contents of α-tocotrienols (58.9 mg/kg) and phytosterols (2310.4 mg/kg), while GZ-MO was rich in squalene (626.7 mg/kg) and YN-MO had the highest levels of polyphenols (71.0 mg GAE/kg) and antioxidant capacity. Based on the correlation analysis, the polyphenols and α-tocotrienols had a remarkable contribution on the antioxidant activities of MO. Furthermore, the cultivation areas of MO can be distinguished according to the analysis of hierachical cluster analysis and principal components. Our studies offer a potential guidance for the identification of MO and its application in food industry.展开更多
The sparse nature of location finding in the spatial domain makes it possible to exploit the Compressive Sensing (CS) theory for wireless location.CS-based location algorithm can largely reduce the number of online me...The sparse nature of location finding in the spatial domain makes it possible to exploit the Compressive Sensing (CS) theory for wireless location.CS-based location algorithm can largely reduce the number of online measurements while achieving a high level of localization accuracy,which makes the CS-based solution very attractive for indoor positioning.However,CS theory offers exact deterministic recovery of the sparse or compressible signals under two basic restriction conditions of sparsity and incoherence.In order to achieve a good recovery performance of sparse signals,CS-based solution needs to construct an efficient CS model.The model must satisfy the practical application requirements as well as following theoretical restrictions.In this paper,we propose two novel CS-based location solutions based on two different points of view:the CS-based algorithm with raising-dimension pre-processing and the CS-based algorithm with Minor Component Analysis (MCA).Analytical studies and simulations indicate that the proposed novel schemes achieve much higher localization accuracy.展开更多
Oxidative deterioration of vegetable oils is of great importance in the food industry.In China,vegetable oils produced via thermal pretreatment are popular owing to their strong oil flavor and enhanced yield.Here,we r...Oxidative deterioration of vegetable oils is of great importance in the food industry.In China,vegetable oils produced via thermal pretreatment are popular owing to their strong oil flavor and enhanced yield.Here,we review:(i)the currently employed thermal treatment methods of oilseeds before oil extraction;(ii)effects of thermal treatments on the physicochemical properties,contents of minor lipid components,and oxidative stability of vegetable oils;and(iii)Maillard model systems that are related to oil and oilseed chemistry.Among the thermal pretreatment technologies,microwave and infrared radiations are promising,but these are not performed on the same large production scales as roasting.For most oilseeds,thermal treatments increase the yield of extracted oil and content of minor lipid compounds in the oil,such as polyphenols,tocopherols,and phytosterols.In addition,some Maillard reaction products(MRPs)generated by heating oilseeds have been extracted.The presence of both minor lipids and MRPs in the oil confers improved oxidative stability.However,the mechanism or relationship between thermal treatment and oxidative stability is yet to be clearly elucidated because vegetable oil oxidation is dependent on variables such as unsaturation,concentration and types of minor lipid components,MRPs,and the potential synergistic effects of these components.Recently,several Maillard reaction models related to thermally treated oilseeds have been established,suggesting that MRPs play a critical role during oxidation.However,comprehensive identification of antioxidants and the mechanism by which they inhibit oxidation are lacking.Future research can be performed to establish models that would help elucidate the antioxidative mechanisms of MRPs for more oilseeds.Using these models,it will be possible to predict the oil quality after processing,based on the presence of MRPs and oil chemistry.展开更多
基金supported by the National Natural Science Foundation of China(22078281)。
文摘The isolation of minor components from complex natural product matrices presents a significant challenge in the field of purification science due to their low concentrations and the presence of structurally similar compounds.This study introduces an optimized twin-column recycling chromatography method for the efficient and simultaneous purification of these elusive constituents.By introducing water at a small flowing rate between the twin columns,a step solvent gradient is created,by which the leading edge of concentration band would migrate at a slower rate than the trailing edge as it flowing from the upstream to downstream column.Hence,the band broadening is counterbalanced,resulting in an enrichment effect for those minor components in separation process.Herein,two target substances,which showed similar peak position in high performance liquid chromatography(HPLC)and did not exceed 1.8%in crude paclitaxel were selected as target compounds for separation.By using the twin-column recycling chromatography with a step solvent gradient,a successful purification was achieved in getting the two with the purity almost 100%.We suggest this method is suitable for the separation of most components in natural produces,which shows higher precision and recovery rate compared with the common lab-operated separation ways for natural products(thin-layer chromatography and prep-HPLC).
基金supported by National Natural Science Foundation,China(Grant No.32160572,32101948)China Postdoctoral Science Foundation,China(Grant No.2020M6832211)+1 种基金Natural Science Foundation of Hainan Province(Grant No.320QN320)Postdoctoral Foundation of Guangxi Academy of Agricultural Sciences(Grant No.2020037).
文摘Macadamia is rich in lipids and considered as a source of high-quality oil. In this study, fatty acids, triacylglycerols, minor components and antioxidant activities of macadamia oils (MOs) from four cultivated regions (YN: Yunnan Province;GZ: Guizhou Province;GX: Guangxi Province;GD: Guangdong Province) in China were systematically analyzed by modern chromatography (Gas chromatography, high performance liquid chromatography, inductively coupled plasma mass spectrometry and ultraviolet spectroscopy). The analysis indicated macadamia oil enriched in unsaturated fatty acids (UFA), including 62.4%–65.6% oleic acid and 11.4%–17.3% palmitoleic acid. Among the four cultivated regions, the MO from YN exhibited the highest contents of UFA (85.0%) and palmitoleic acid. In addition, the minor components and antioxidant activities of MO from four cultivation areas showed a significant difference, which GX-MO had the highest contents of α-tocotrienols (58.9 mg/kg) and phytosterols (2310.4 mg/kg), while GZ-MO was rich in squalene (626.7 mg/kg) and YN-MO had the highest levels of polyphenols (71.0 mg GAE/kg) and antioxidant capacity. Based on the correlation analysis, the polyphenols and α-tocotrienols had a remarkable contribution on the antioxidant activities of MO. Furthermore, the cultivation areas of MO can be distinguished according to the analysis of hierachical cluster analysis and principal components. Our studies offer a potential guidance for the identification of MO and its application in food industry.
基金supported by the National Natural Science Foundation of China under Grant No.61001119the Fund for Creative Research Groups of China under Grant No.61121001
文摘The sparse nature of location finding in the spatial domain makes it possible to exploit the Compressive Sensing (CS) theory for wireless location.CS-based location algorithm can largely reduce the number of online measurements while achieving a high level of localization accuracy,which makes the CS-based solution very attractive for indoor positioning.However,CS theory offers exact deterministic recovery of the sparse or compressible signals under two basic restriction conditions of sparsity and incoherence.In order to achieve a good recovery performance of sparse signals,CS-based solution needs to construct an efficient CS model.The model must satisfy the practical application requirements as well as following theoretical restrictions.In this paper,we propose two novel CS-based location solutions based on two different points of view:the CS-based algorithm with raising-dimension pre-processing and the CS-based algorithm with Minor Component Analysis (MCA).Analytical studies and simulations indicate that the proposed novel schemes achieve much higher localization accuracy.
基金supported by the National Natural Science Founda-tion of China(Grants No.31920103012 and 31901603)China Postdoc-toral Science Foundation(Grant No.2019M663386)the Science and Technology Project of Guangzhou City(Grant No.201903010049).
文摘Oxidative deterioration of vegetable oils is of great importance in the food industry.In China,vegetable oils produced via thermal pretreatment are popular owing to their strong oil flavor and enhanced yield.Here,we review:(i)the currently employed thermal treatment methods of oilseeds before oil extraction;(ii)effects of thermal treatments on the physicochemical properties,contents of minor lipid components,and oxidative stability of vegetable oils;and(iii)Maillard model systems that are related to oil and oilseed chemistry.Among the thermal pretreatment technologies,microwave and infrared radiations are promising,but these are not performed on the same large production scales as roasting.For most oilseeds,thermal treatments increase the yield of extracted oil and content of minor lipid compounds in the oil,such as polyphenols,tocopherols,and phytosterols.In addition,some Maillard reaction products(MRPs)generated by heating oilseeds have been extracted.The presence of both minor lipids and MRPs in the oil confers improved oxidative stability.However,the mechanism or relationship between thermal treatment and oxidative stability is yet to be clearly elucidated because vegetable oil oxidation is dependent on variables such as unsaturation,concentration and types of minor lipid components,MRPs,and the potential synergistic effects of these components.Recently,several Maillard reaction models related to thermally treated oilseeds have been established,suggesting that MRPs play a critical role during oxidation.However,comprehensive identification of antioxidants and the mechanism by which they inhibit oxidation are lacking.Future research can be performed to establish models that would help elucidate the antioxidative mechanisms of MRPs for more oilseeds.Using these models,it will be possible to predict the oil quality after processing,based on the presence of MRPs and oil chemistry.
