Microwave-assisted aqueous two-phase extraction of alkaloids from Radix Sophorae Tonkinensis with ethanol/Na2HPO4 system: process optimization, composition identification and quantification analysis

A rapid method for simultaneous extraction and separation of multiple alkaloids from Radix Sophorae Tonkinensis (RST) was developed by microwave-assisted aqueous two-phase extraction (MAATPE) using the aqueous two-phase extraction system (ATPS) of ethanol/Na2HPO4 as the extraction solvent. The effects of key factors on extraction yield were investigated by utilizing single-factor experiment coupled to response surface methodology (RSM). The regression model by RSM was significant (p < 0.0001) and adequate for prediction of process efficacy, the optimized conditions were successfully validated by the parallel experiments with the yield very close to the predicted value. The optimum conditions were summarized as follows: the phase ratio of 2.60 for the ATPS, the particle size of 100 mesh, the liquid-to-material ratio of 75:1, the extraction temperature of 90 °C and the extraction time of 5 min, respectively. In MAATPE process, alkaloids were extracted preferentially from RST in the top phase with a higher yield and shorter extraction time than those of heating reflux extraction (HRE) and ultrasonic-assisted extraction (UAE). Nine alkaloids extracted were identified and quantified by high-resolution ultra-performance liquid chromatography-quadrupole-orbitrap mass spectrometry (UPLC-Q-Orbitrap/MS) and HPLC with UV detection. The contents of matrine, sophocarpine, oxymatrin, sophoranol, oxysophocarpine, 5α-hydroxysophocarpine, sophoridine, cytisine and N-methylcytisine in RST were quantified in range of 0.493–10.284 mg/g with recoveries of 90.26–106.3% and RSD’s of 0.8–2.1%, respectively. Moreover, the MAATPE mechanism was explored using the different extraction systems in combination of scanning electron microscopy (SEM) morphological studies. Significant differences in extraction yield and cell rupture exhibited that the addition of the salt in the ethanol-water mixture not only improved the thermal and demixing effects, but also accelerated the mass transfer and biphasic extraction processes. MAATPE integrated the advantages of microwave-assisted extraction (MAE) and aqueous two-phase extraction (ATPE) was proved as a green, efficient and promising alternative to extraction of alkaloids from RST

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En Chine, avec l’établissement progressif du système d’économie de marché socialiste, les formes et la quantité de propriété privée des citoyens ont connu une évolution constante. L’amendement constitutionnel de 2004 a officiellement consacré la protection du droit de propriété privée dans la constitution. Un système juridique initial de protection du droit de propriété privée, qui a objectivement favorisé l’essor de l’économie chinoise, a été établi. Cependant, nous devons être conscients que la situation actuelle de la protection du droit de propriété privée n’est pas optimiste en Chine. Le point essentiel du problème réside non seulement dans les divers défauts de système juridique de la propriété privée, mais également dans le fait que les normes constitutionnelles sur la garantie du droit de propriété des citoyens n’ont pas été efficacement mises en œuvre. Le 19ème Congrès national du Parti communiste chinois de 2017 a proclamé officiellement l’objectif de faire progresser le système de contrôle de constitutionnalité, et ensuite, l’amendement constitutionnel de 2018 a établi une nouvelle commission spéciale destinée à effectuer un examen constitutionnel. Ces deux événements signifient-ils que la Chine s’est bien préparée pour la construction d’un État de droit, qui a pour effet d’améliorer le système actuel de protection constitutionnelle du droit de propriété des citoyens ? Partant de cette question, la présente thèse choisit donc une perspective de mise en œuvre de la constitution et utilise l’expérience du droit français comme référence, afin d’étudier le système de la protection du droit de propriété privée en ChineIn China, with the gradual establishment of the socialist market economy, the form and quantity of ownership of citizens have evolved constantly. The constitutional amendment of 2004 has formally consecrated the property rights in the constitution. An initial legal system of protection of property right, which has objectively favored the development of the Chinese economy, has been established. However, we must be aware that the current situation of the protection of property rights is not optimistic in China. The essential point of the problem lies not only in the various deficiencies of the legal system of property, but also in the fact that the constitutional laws on the guarantee of the property right of the citizens have not been effectively implemented. The 19th National congress of the Chinese communist party has formally proclaimed the purpose of advancing the constitutional examination system, and then the constitutional amendment of 2018 established a new special commission to carry out it. Do these two events mean that China has prepared well for the construction of the rule of law, which has the effect of improving the current system of constitutional protection of the property rights of citizens? Starting from this question, the present thesis thus chooses a perspective of the implementation of the constitution and uses the experience of the French law as reference, in order to study the system of the protection of the property right in Chin

A Bibliometric Visualized Analysis and Classification of Vehicle Routing Problem Research

The vehicle routing problem (VRP), as a classic combinatorial optimization problem, has always been a hot research topic in operations research. In order to gain a deeper understanding of the VRP problem, this work uses the knowledge graph to comprehensively analyze and summarize the literature related to VRP from 1959 to 2022 in the Web of Science (WoS) database. Firstly, according to the basic statistical information of the literature, the annual publications, the authors, their institutions and countries, the keyword co-occurrence, and the literature co-citation network are analyzed to comprehensively summarize and generalize the research on VRP and predict its future development trend. The results show that, in the past 60 years, there have been abundant changes in the research on VRP. The United States and China have made the most important contributions in the field of VRP. According to the WoS literature retrieval results and classification methods, the VRP models and their solutions are comprehensively classified, and the model solving algorithms are divided into exact algorithms, heuristic algorithms, metaheuristic algorithms, hyper-heuristic algorithms, machine learning, etc. The results show that the development of information computing technology plays an important role in research on the VRP problem, and dynamic VRP, hyper-heuristic algorithms, deep reinforcement learning, etc. are the future development directions of the VRP model and its optimization. The results of this research can provide help and guidance for beginners and scholars outside the industry to comprehensively understand the development and research hotspots of VRP

Correction: Tang et al. Can El Ni&ntilde;o&ndash;Southern Oscillation Increase Respiratory Infectious Diseases in China? An Empirical Study of 31 Provinces. Int. J. Environ. Res. Public Health 2022, 19, 2971

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