Supercritical CO2 extraction of triterpenoids from Inonotus obliquus

Inonotus obliquus (Fr.) Pilát, is a basidiomycete, which can be found mainly above the 40th parallel north of Europe, Asia and America. The usage of the sterile conk, also known as Chaga, as folk medicine in Baltic countries goes back to the 17th century. Traditionally, Chaga extracts have been used for treating cancer. Chemical investigations have shown that Chaga contains high quantities of bioactive compounds such as triterpenoids, which have been connected to the health benefits and immuno-modulating effects of Chaga. Supercritical fluid extraction (SFE) of Chaga was carried out with pure CO2 to recover triterpenoids, while a modified Folch extraction method was used as comparison. Along with the extraction, one of the main purposes of this work was to determine the optimal extraction parameters for SFE by analysing the compositions of the extracts. The main attractions of SFE are less laborious and time-consuming operation but also the fact that hazardous solvents can be omitted from the extraction process. The high selectivity and inert nature of CO2 also makes it possible to target and remove certain substances from the sample material without remarkably affecting the structure of the material. Three temperature-pressure combinations were tested in SFE varying between 40-50°C and 281-350 bars, in order to find suitable conditions for triterpenoid extraction. The extracts were saponified and the recovered triterpenoids analysed as trimethylsilyl (TMS) ethers. A gas chromatographic system coupled with flame ionization detector (GC-FID) was used for quantification, while mass spectrometry (GC-MS) was used for the identification. Six sterol and triterpenoid constituents were identified and quantified from supercritical fluid (SF) extracts: ergosterol (17.9±1.3 mg / 100 g dry weight), lanosterol (65.5±7.2 mg / 100 g), β- sitosterol (3.6±0.5 mg / 100 g), stigmastanol (1.4±0.1 mg / 100 g), betulin (13.2±4.3 mg / 100 g) and inotodiol (97.7±11.5 mg / 100 g). Folch extracts produced higher yield in ergosterol (36.7±1.5 mg / 100 g), inotodiol (127.7±5.5 mg / 100 g), betulin (34.7±4.2 mg / 100 g), lanosterol (74.1±1.0 mg / 100 g), β-sitosterol (5.0±0.4 mg / 100 g) and stigmastanol (1.8±0.2 mg / 100 g). The difference was found to be statistically significant between Folch method and SFE (p < 0.05). Trametenolic acid was found only in Folch extracts, in relatively high amounts (44.8±1.0 mg / 100 g). Despite the lower yield obtained by SFE, this method showed several advantages including significantly shorter extraction time and production of solvent waste. This work could be a starting point for further studies on green extraction methods of bioactive compounds from Finnish natural resources. The utilized methods can be further developed to achieve more efficient extraction conditions compared to Folch method

Preservice Teachers’ Identity Development during the Teaching Internship

This article reports the analysis of two preservice teachers’ narratives to highlight the process of teacher identity development during their teaching internship. The analysis showed that their teacher identities had been shaped before they entered the teacher education program where it continued to be shaped by educational experts. In that way, they formed expectations or imaginations of their professional roles and responsibilities prior to the teaching internships. When entering the teaching internships, these pre-existing expectations or imaginations were challenged by the reality they faced. Their engagement with the internship, resilience and negotiations of professional practices were found to be significant for the development of their teacher identities. The article discusses some important implications for teacher education programs

Research Notes: Effect of nutrient foliar application and seeding rate on promising soybean varieties in Mekong Delta , Vietnam

In order to boost grain yield of soybeans by cultural practices, an experiment was carried out with two most promising soybean varieties in Mekong Delta , VN. The experimental design is split plot design with three replicates . Plot size is 6. 5m x 2m , with and/or without nutrient foliar spraying in main plots , and seeding rate is in subplots with four different seeding treatments: 40 x 20 cm, 40 x 5 cm, 30 x 10 cm and 30 x 5 cm that is, from 25 plants per square meter to 66 plants per square meter

A Passivity-based Control Combined with Sliding Mode Control for a DC-DC Boost Power Converter

In this paper, a passivity-based control combined with sliding mode control for a DC-DC boost power converter is proposed. Moreover, a passivity-based control for a DC-DC boost power converter is also proposed. Using a co-ordinate transformation of state variables and control input, a DC-DC boost power converter is passive. A new plant is zero-state observable and the equilibrium point at origin of this plant is asymptotically stable. Then, a passivity-based control is applied to this plant such that the capacitor voltage is equal to the desired voltage. Additionally, the sliding mode control law is chosen such that the derivative of Lyapunov function is negative semidefinite. Finally, a passivity-based control combined with sliding mode control law is applied to this plant such that the capacitor voltage is equal to the desired voltage. The simulation results of the passivity-based control, the sliding mode control and the passivity-based control combined with sliding mode control demonstrate the effectiveness and show that the capacitor voltage is kept at the desired voltage when the desired voltage, the input voltage E and the load resistor R are changed. The results show that compared with the passivity-based control, the passivity-based control combined with sliding mode control has better performance such as shorter settling time, 8.5 ms when R changes and it has smaller steady-state error, which is indicated by the value of integral absolute error (IAE), 0.0679 when the desired voltage changes. The paper has limitations such as the assumed circuit parameters

Factors Affecting the Agricultural Restructuration: A Case of Cham Community in Chau Phu District, An Giang Province, Vietnam

The national policy of agricultural restructuring plays a vital role in adapting to climate change's effects and economic development in the Mekong Delta of Vietnam. Unproductive areas have been converted into other crops with higher efficiency. Drawn by the sustainable livelihoods approach, this article explores the current situation and factors challenging the Cham community in implementing the agricultural restructuring. The mixed method included in-depth interviews, focus group discussions, and a questionnaire survey. The results showed that the Xuong Com Vang longan (Dimocarpus longan) variety has occurred in Khanh Hoa commune for a long time as an indigenous fruit tree of this area. In terms of the farming system, the polyculture system combining fruit trees and upland crops brought more income sources than the monoculture system. The asset abilities of the Cham farmers are various from one to the others. Soil and weather conditions are appropriate for planting. But farm size is small, which is one of the difficulties of developing fruit areas. Human and social assets were good since farmers had enough knowledge to manage the gardens, and a close connection existed among the Cham community. It was not a case of the financial status since a lot of money needs to be invested in the starting year. Therefore, the private loan still exists as one of the farmer's choices. For better future development, land management and financial resource should be considered for better agricultural restructuring aims. To increase farmers' incomes, create production chains helping enterprises and farmers work more efficiently for the better life of Cham gardeners in An Giang province in Vietnam

Load Shedding in Microgrid System with Combination of AHP Algorithm and Hybrid ANN-ACO Algorithm

This paper proposes a new load shedding method based on the application of intelligent algorithms, the process of calculating and load shedding is carried out in two stages. Stage-1 uses a backpropagation neural network to classify faults in the system, thereby determining whether or not to shed the load in that particular case. Stage-2 uses an artificial neural network combined with an ant colony algorithm (ANN-ACO) to determine a load shedding strategy. The AHP algorithm is applied to propose load shedding strategies based on ranking the importance of loads in the system. The proposed method in the article helps to solve the integrated problem of load shedding, classifying the fault to determine whether or not to shedding the load and proposing a correct strategy for shedding the load. The IEEE 25-bus 8-generator power system is used to simulate and test the effectiveness of the proposed method, the results show that the frequency of recovery is good in the allowable range

Ranking load in microgrid based on fuzzy analytic hierarchy process and technique for order of preference by similarity to ideal solution algorithm for load shedding problem

This paper proposes a method to rank the loads in the microgrid by means of a weight that combines the criteria together in terms of both technical and economic aspects. The fuzzy analytic hierarchy process technique for order of preference by similarity to ideal solution (fuzzy AHP TOPSIS) algorithm is used to calculate this combined weight. The criteria to be considered are load importance factor (LIF), voltage electrical distance (VED) and voltage sensitivity index (VSI). The fuzzy algorithm helps to fuzzy the judgment matrix of the analytic hierarchy process (AHP) method, making it easier to compare objects with each other and remove the uncertainty of the AHP method. The technique for order of preference by similarity to ideal solution (TOPSIS) algorithm is used to normalize the decision matrix, determine the positive and negative ideal solutions to calculate the index of proximity to the ideal solution, and finally rank all the alternatives. The combination of fuzzy AHP and TOPSIS algorithms is the optimal combination for decision making and ranking problems in a multi-criteria environment. The 19-bus microgrid system is applied to calculate and demonstrate the effectiveness of the proposed method

STIRLING ENGINE: FROM DESIGN TO APPLICATION INTO PRACTICE AND EDUCATION

Stirling motor is a type of outside ignition heat motor that can utilize various fuel sources from customary structures (coal, oil, kindling, rice husk, and so forth) to sustainable power sources (sun-oriented energy), climate, squander heat usage, and so forth). The article centers around introducing the fundamental highlights of the improvement history, activity qualities, and plan techniques for certain sorts of Stirling motors, in this way offering useful appropriateness as well as a college preparing for understudies. The understudy studying Thermal Engineering in our nation today.  

Supercritical CO2 Extraction of Triterpenoids from Chaga Sterile Conk of Inonotus obliquus

Triterpenoids are among the bioactive components of Chaga, the sterile conk of the medicinal fungus Inonotus obliquus. Supercritical fluid extraction of Chaga triterpenoids was carried out with supercritical CO2, while a modified Folch method was used as a comparison. Three temperature-pressure combinations were tested varying between 314-324 K (40-50 degrees C) and 281-350 bars, using time- and volume-limited extractions. Six triterpenoids were identified with GC-MS and quantified with GC-FID: ergosterol, lanosterol, beta-sitosterol, stigmastanol, betulin, and inotodiol. The Folch extraction resulted in recovery of trametenolic acid, which was not extracted by supercritical CO2. Inotodiol was the major triterpenoid of all the extracts, with a yield of 87-101 mg/100 g and 139 mg/100 g, for SFEs and the Folch method, respectively. The contents of other major triterpenoids, lanosterol and ergosterol, varied in the ranges 59-63 mg/100 g and 17-18 mg/100 g by SFE, respectively. With the Folch method, the yields were 81 mg/100 g and 40 mg/100 g, respectively. The highest recovery of triterpenoids with SFE in relation to Folch was 56% and it was obtained at 324 K (50 degrees C) and 350 bar, regardless of extraction time or volume of CO2. The recoveries of lanosterol and stigmastanol were unaffected by SFE conditions. Despite the lower yield, SFE showed several advantages including shorter extraction time and less impact on the environment. This work could be a starting point for further studies on green extraction methods of bioactive triterpenoids from Chaga