Search

Objective: This study aimed to improve the recrystallization yield and purity of flavonoid. Methods: Taking the crude flavonoids from pomelo peel extracted by ultrasonic-assisted ethanol extraction as raw materials, the process parameters of ethanol recrystallization and purification of flavonoids were optimized by response surface methodology. Results: The main factors affecting the recrystallization yield of flavonoids were ethanol concentration, crystallization time, pH value, and the interaction between ethanol concentration and pH value, among which, the ethanol concentration affacted most significantly. Conclusion: The optimal recrystallization conditions of flavonoids were as follows: ethanol volume fraction of 24%, liquid-solid ratio of 10∶1 (mL/g), pH 3.75, crystallization temperature of 4 ℃, and crystallization time of 24 h. The crystallization yield of flavonoids was 8.76%, and the main crystallization product was naringin with a purity of 83.38%.

It is important to eliminate the fishy odor and improve the aroma quality of seafood. In this study, the Saccharina japonica (S. japonica) seedling, which is a new food material, was investigated for the effects of fermentation with Saccharomyces cerevisiae (S. cerevisiae) through sensory evaluation, GC–MS, and odor activity value (OAV) analysis. GC–MS analysis revealed the presence of 43 volatile compounds in the unfermented S. japonica seedling, with 1-octen-3-ol, hexanal, and trans-2,4-decadienal identified as the main contributors to its fishy odor. After fermentation with S. cerevisiae, 26 volatile compounds were identified in the S. japonica seedling. Notably, the major malodorous fish compounds, including 1-octen-3-ol, hexanal and trans-2,4-decadienal, were no longer present. The results indicate that fermentation with S. cerevisiae is an effective method for removing fishy malodor compounds and enhancing the volatile components with fruity, sweet, green, and floral notes in the Saccharina japonica seedling. This process facilitates the elimination of fishy malodor and enhance the fruity, sweet, green, and floral notes of S. japonica seeding and other seaweeds. [ABSTRACT FROM AUTHOR]

The expansion of deformation-induced crystallization of polypropylene (PP) pipes was studied. The crystal structure and melting characteristics of the samples after expanding at different expansion strains and expansion temperatures were analyzed. The results showed that the ciystallinity was improved when the PP pipes were expanded, and the expansion effect made the crystal structure more perfect while the expanding temperature did not exceed the crystallization temperature. However, once expanding temperature exceeded crystallization temperature, some [beta] lamellae crystal were stretched and transformed into a crystals structure. It showed that the expansion effect could cause the crystal phase transformation of the sample. In addition, when the expanding strain was less than 15%, the [beta] crystal diffraction peak intensity of the sample decreased, but the a crystal diffraction peak intensity increased, and the original sparse distribution lamellae structure gradually became compact. With the expanding strain continued to increase, the oriented molecular chains underwent stress relaxation, which hindered the conversion of [beta] crystals to a crystals. The oriented crystal structure formed by the crystal phase transformation made the PP pipe have excellent tensile and impact strength. As a result, the hoop tensile strength is increased by 13%, and the impact strengths are increased by 36%. KEYWORDS expanding, phase transformation, PP pipe, [beta] crystals, 1 | INTRODUCTION As we all know, polypropylene is widely used in packaging, home appliances, and automobiles due to its good mechanical properties and easy processing and molding. [1-4] As [...]

The unique edge states of the zigzag β-SiC7 nanoribbons aroused our attention, and therefore, based on first-principles calculations, we investigated their spin-dependent electronic transport properties by constructing controllable defects to modulate these special edge states. Interestingly, by introducing rectangular edge defects in the SiSi and SiC edge-terminated systems, not only the spin-unpolarized is successfully converted to completely spin-polarized, but also the direction of polarization can be switched, thus enabling a dual spin filter. The analyses further reveal that the two transmission channels with opposite spins are spatially separated and that the transmission eigenstates are highly concentrated at the relative edges. The specific edge defect introduced only suppresses the transmission channel at the same edge but reserves the transmission channel at the other edge. In addition, for the CSi and CC edge-terminated systems, an additional spin-down band exists due to spin splitting in the spin-up band at EF, so that besides the original spatially separated two spin-opposite channels, an extra spin channel is distributed at the upper edge, resulting in unidirectional fully spin-polarized transport. The peculiar spatially separated edge states and excellent spin filtering properties could open up further possibilities for β-SiC7-based electronic devices in spintronics applications. [ABSTRACT FROM AUTHOR]

Objective: In order to control the potassium ion content in Carrageenan, this project used alcohol inhibition method instead of potassium ion solution to extract Carrageenan. Methods: The volume fraction of ethanol in the processes of alkali treatment, alkali residual cleaning, and precipitation of carrageenan after filtration during the extraction were optimized for controlling K+ concentration. Results: The concentration of ethanol to inhibit the dissolution of Carrageenan was 60% in the process of alkali treatment and cleaning residual alkali, and the ratio of 60% ethanol solution to glue solution was 5∶1 in the process of Carrageenan precipitation. By using this process, the yield of Carrageenan was （28.76±1.38）%, and the Carrageenan of potassium ion was 0.63%, which was significantly lower than that of potassium ion extracted from traditional Carrageenan （16.26%）. In addition, the gel strength was significantly lower than that of Carrageenan extracted by traditional methods. And there was no significant difference in viscosity, hardness, elasticity, chewiness, and recovery between the two methods. Conclusion: K+ concentration and gel strength of Kappa-carrageenan extracted by ethanol inhibition were significantly lower than traditional technology.

The aim of this paper was to explore the process of β-glucosidase-assisted extraction of flavonoids from thinned fruits of Guanxi pummelo and the inhibitory effect of the extracted flavonoids on tyrosinase. In this paper, the extraction amount of total flavonoids was used as the index, and the β-glucosidase activity, enzymatic hydrolysis pH, temperature and time were optimized by single factor and response surface experiments, and the inhibitory effect of total flavonoids extract on tyrosinase was studied. The results showed that the optimal conditions for the extraction of flavonoids from thinned fruits of Guanxi pummelo were as follows: β-Glucosidase enzyme activity 0.0128 U/mL, enzymolysis pH4.4, temperature 35 t, time 4.8 h. Under these conditions, the extraction amount of total flavonoids was 34.0 mg/g, the half maximal inhibitory concentration (IC50) of the flavonoids extract on tyrosinase was 0.31 mg/mL. The results of this study showed that the enzymatic process could significantly improve the extraction amount of flavonoids from thinned fruits of Guanxi pummelo, and the flavonoids from thinned fruits of Guanxi pummelo had strong tyrosinase inhibition. The results of this study provided a reference for the extraction and application of flavonoids from thinned fruits of Guanxi pummelo, which was conducive to promoting the high-value utilization of Guanxi pummelo. [ABSTRACT FROM AUTHOR]

Plasma treatment as an effective strategy can simultaneously achieve surface modification and heteroatom doping. Here, an N/P-doped NiFeV oxide nanosheet catalyst (N/P-NiFeVO) constructed by Ar/PH3 plasma treatment is used to drive the oxygen evolution reaction (OER). The introduction of V species leads to the formation of an ultrathin ordered nanostructure and exposure of more active sites. Compared to the 2D NiFeV LDH, the prepared N/P-NiFeVO by plasma treatment possesses multiple-valence Fe, V and Ni species, which regulate the intrinsic electronic structure and enable a superior catalytic activity for the OER in alkaline media. Specifically, the N/P-NiFeVO only require an overpotential of 273 mV to drive the current density of 100 mA cm−2. What's more, the electrode can maintain a stable current density in a long-term oxygen evolution reaction (∼120 h) under alkaline conditions. This work provides new insight for the rational design of mixed metal oxides for OER electrocatalysts. [ABSTRACT FROM AUTHOR]