In this work a comparative study on phytochemical profiles of comfrey root extracts obtained by different extraction approaches has been carried out. Chemical profiles of extracts obtained by ...supercritical fluid (SFE), pressurized liquid (PLE), and conventional solid/liquid extraction were compared and discussed. Phytochemical composition was assessed by high-performance liquid chromatography coupled with electrospray time-of-flight mass spectrometry (HPLC-ESI-QTOF-MS/MS) identifying 39 compounds reported for the first time in comfrey root, mainly phenolic acids and fatty acids. The influence of different extraction parameters on phytochemical profiles of
root was investigated for all applied techniques. PLE and maceration, using alcohol-based solvents (aqueous methanol or ethanol), were shown to be more efficient in the recovery of more polar compounds. Greater numbers of phenolics were best extracted by PLE using 85% EtOH at 63 °C. The use of SFE and 100% acetone for 30 min enabled good recoveries of nonpolar compounds. SFE using 15% EtOH as a cosolvent at 150 bar produced the best recoveries of a significant number of fatty acids. The main compositional differences between extracts obtained by different extraction techniques were assigned to the solvent type. Hence, these results provided comprehensive approaches for treating comfrey root enriched in different phytochemicals, thereby enhancing its bioaccessibility.
Wearable auxiliary devices for visually impaired people are highly attractive research topics. Although many proposed wearable navigation devices can assist visually impaired people in obstacle ...avoidance and navigation, these devices cannot feedback detailed information about the obstacles or help the visually impaired understand the environment. In this paper, we proposed a wearable navigation device for the visually impaired by integrating the semantic visual SLAM (Simultaneous Localization And Mapping) and the newly launched powerful mobile computing platform. This system uses an Image-Depth (RGB-D) camera based on structured light as the sensor, as the control center. We also focused on the technology that combines SLAM technology with the extraction of semantic information from the environment. It ensures that the computing platform understands the surrounding environment in real-time and can feed it back to the visually impaired in the form of voice broadcast. Finally, we tested the performance of the proposed semantic visual SLAM system on this device. The results indicate that the system can run in real-time on a wearable navigation device with sufficient accuracy.
In the 5th Generation (5G) positioning, the accurate values of environmental parameters such as Pathloss exponent (PLE) and transmit power are difficult to obtain accurately. Methods based on the ...difference of received signal strength (DRSS) can be utilized to solve the problems. An estimation method to obtain the distance ratio is given, and a distance ratio positioning model is proposed. The initial positioning results are calculated with linear least squares (LLS) algorithm. A Levenberg-Marquardt (LM) based maximum a posteriori (MAP) algorithm is proposed to obtain the final result by performing a series of iterations. We have completed the 5G field data collection in urban environments and preprocessed the raw data in 5G field experiments. We also propose a judgment method for 5G positioning based on horizontal dilution of precision (HDOP). Compared to the state-of-art DRSS-based algorithms, the proposed method has the best positioning accuracy and achieves a positioning error of 43.8 meters for 80% of samples with six base stations.
In order to solve the security problem for fading channel, a pragmatic physical layer encryption (PLE) scheme is proposed, which utilises diversity technique elaborately. Different from the ...conventional PLE schemes based on phase rotation for the modulated symbol, the proposed scheme changed phase and amplitude together for a block of symbols each time, which can be defined as multi-dimensional PLE (MPLE). Unconventional constellation obfuscates eavesdropper, which can be seen as the first level security in the physical layer. The correct probability based on chosen plaintext attacks and known plaintext attacks is deduced. It can be seen from the simulation results that the MPLE scheme can achieve lower attack success probability because of multi-level security and better performance based on diversity under fading channel.
The concentrations of 19 brominated flame retardants (BFRs) (8 polybrominated diphenyl ethers (PBDEs), 8 methoxylated PBDEs (MeO-PBDEs) and 3 emerging flame retardants) were determined in 10 species ...of fish and shellfish widely consumed in Tarragona County (Catalonia, Spain), by pressurized liquid extraction followed by gas chromatography coupled to tandem mass spectrometry. A higher occurrence of PBDEs was found in all the analyzed samples, while MeO-PBDEs were only detected in a few ones and the levels of emerging pollutants were relatively low. In contrast, hexabromobenzene was found in almost all samples at concentrations ranging between non detected and 0.2 ng g−1 wet weight (w.w.). Salmon, sole, hake, cod and tuna showed the highest concentrations of ΣPBDEs (>0.8 ng g−1 w.w.), while mussel was the species with the highest level of MeO-PBDEs (1.5 ng g−1 w.w.). The dietary exposure of BFRs through consumption of these 10 species of fish and shellfish by the population of Tarragona County was estimated for different subpopulations, classified according to age and gender. Furthermore, calculations were performed in upper-, middle- and lower-bound risk scenarios. According to our data, the current concentrations of BFRs in fish and shellfish suggest no significant health risks for the consumers.
•A number of BFRs was found in fish and shellfish from Tarragona County market.•BDE47 and 28 were the congeners with the highest levels in the analyzed samples.•Trace levels of some MeO-PBDEs were present in the main commercial fish species.•HBB was identified in most samples, while PBEB and DBDPE were not detected in any.•The dietary exposure to BFRs does not pose human health risks in Tarragona County.
The purpose of the research study was to propose personal learning environments to foster metacognitive development for sixth semester students of the Systems Engineering program at higher education ...institutions including Cecar, Corposucre and Unad, all of them based in the city of Sincelejo (Sucre-Colombia). To that end, a descriptive methodology, under a non-experimental, transversal and field design was proposed. The population was made up of 68 students. A survey was used as a data collection technique and a 24-question questionnaire was applied, with five alternative options included. It was validated by five experts and its reliability was determined through the application of the Cronbach’s alpha formula, which yielded a value of 0.87523 (highly reliable). The findings indicate that it is necessary to propose personal learning environments as a pedagogical option for the development of students' metacognitive skills. Accordingly, a personal learning environment was proposed for the development of metacognition including guidelines and action strategies that improve metacognitive skills, based on self-regulated and self-directed learning of systems engineering students.
Lead (Pb) is a non-essential heavy metal found as an inorganic pollutant in the water, sediment, and mangrove plant tissue in Wonorejo River Estuary. Several studies showed that its concentration ...exceeds the quality standard stipulated in the Indonesian Government Regulation Number 22 of 2021 and the EPA sediment quality. Moreover, the phytoremediation of Pb through mangroves Avicennia alba, Rhizophora stylosa, Sonneratia caseolaris, and Avicennia marina at Wonorejo River Estuary was investigated. It was discovered that the environmental factors such as temperature, pH, and salinity as well as Bioconcentration Factor (BCF) and Translocation Factor (TF) values are different for each species. The dynamics of the Pb phytoremediation system were also modeled using Vensim PLE x64 software to determine the effect of environmental factors such as temperature, pH, salinity, BOD and COD, as well as Pb concentration on the ability of mangroves to accumulate and translocate Pb. The results showed that a behavioral mechanism pattern was formed based on the relationship between the environmental factors, Pb concentration, and the phytoremediation ability of the mangroves with time. This pattern affected the root and leaf BCF values of each mangrove. Furthermore, the validation test showed that the model is structurally valid and has MAPE values for the Pb phytoremediation model with S. caseolaris and R. stylosa having <30% while Avicennia marina and A. alba had <50%. Therefore, the model was categorized as fairly good with a valid forecast. The system dynamics predicted that the highest concentrations of Pb in water, roots, and stems in 2041 were in R. stylose at 1,329,110 mg/L, 2,054,110 mg/kg, and 3,393,950 mg/kg, respectively. The highest accumulation value in plant tissue was dominated by mangrove species of R. stylose. In conclusion, the environmental parameter values at habitat of R. stylose were in good condition for the growth of the mangroves compared with other species of mangrove.
Having proverbs as the object of study and application in the teaching and learning of Portuguese as a Foreign Language (PLE), a proposal will be presented aiming to provide students with the ...opportunity to expand their vocabulary and refine their understanding of certain sententious statements, using the Spanish language as a bridge language. The choice of this language was based on the context of teaching Portuguese as a Foreign Language to groups of students from different countries around the world. Thecorpus to be worked on in the classroom will start with the presentation of proverbs in Portuguese known and published in the Refranero Multilingüe of the Cervantes Institute. Information on variants and synonyms of these sententious statements will be expanded through the students' research in the RM and in paremiographic repertoires in Portuguese and Spanish. This work will be based on studies by Teixeira de Faria (2021) on synonymy and variation and Sevilla Muñoz & Crida (2017) on the typology of proverbs, among others.
Tendo as parêmias como objeto de estudo e aplicação no ensino-aprendizagem de PLE, será apresentadauma proposta que visa dar aos estudantes a possibilidade de ampliar o vocabulário e depurar a compreensão de certos enunciados sentenciosos, servindo-se da língua espanhola como língua-ponte. A escolha desse idioma fundamentou-se no contexto do ensino de Português como Língua Estrangeira para grupos de estudantes provenientes de diferentes países ao redor do mundo.O corpusa ser trabalhado em sala de aula partirá da apresentação de parêmias em língua portuguesa conhecidas e publicadas no Refranero Multilingüedo Instituto Cervantes. Ampliar-se-á informação de variantes e sinônimos desses enunciados sentenciosos através da pesquisa por parte dos estudantes no RM, assim como em repertórios paremiográficos em português e espanhol. Estetrabalho se apoiará nos estudos de Teixeira de Faria (2021) sobre sinonímia e variante e Sevilla Muñoz & Crida (2017) sobre tipologia das parêmias, entre outros.
Teniendo las paremias como objeto de estudio y su aplicación en la enseñanza y el aprendizaje de PLE, presentaremos una propuesta que visa dar a los estudiantes la posibilidad de ampliar el vocabulario y depurar la comprensión de ciertos enunciados sentenciosos, sirviéndose del Español como lengua-puente. Este idioma fue seleccionado partiendo de la base de la enseñanza de Portugués como Lengua Extranjera a grupos de estudiantes originarios de diversos países del mundo. El corpus a ser trabajado en clase partirá de la presentación de paremias conocidas y publicadas en el Refranero Multilingüe del Instituto Cervantes. Se ampliará la información de variantes y sinónimos de esos enunciados sentenciosos por medio de la consulta de los estudiantes al RM, así comoen repertorios paremiográficos en portugués y español. Nos apoyaremos en los estudios de Teixeira de Faria (2021) sobre sinonimia y variante y Sevilla Muñoz & Crida (2017) sobre tipología de las paremias, entre otros.
In this contribution, the capabilities of pressurized liquid extraction (PLE) using food-grade solvents, such as water and ethanol, to obtain antioxidant extracts rich on polyphenolic compounds from ...olive leaves are studied. Different extraction conditions were tested, and the PLE obtained extracts were characterized
in vitro according to their antioxidant capacity (using the DPPH radical scavenging and the TEAC assays) and total phenols amounts. The most active extracts were obtained with hot pressurized water at 200
°C (EC
50 18.6
μg/mL) and liquid ethanol at 150
°C (EC
50 27.4
μg/mL), attaining at these conditions high extraction yields, around 40 and 30%, respectively. The particular phenolic composition of the obtained extracts was characterized by LC–ESI-MS. Using this method, 25 different phenolic compounds could be tentatively identified, including phenolic acids, secoiridoids, hydroxycinnamic acid derivatives, flavonols and flavones. Among them, hydroxytyrosol, oleuropein and luteolin-glucoside were the main phenolic antioxidants and were quantified on the extracts together with other minor constituents, by means of a UPLC–MS/MS method. Results showed that using water as extracting agent, the amount of phenolic compounds increased with the extraction temperature, being hydroxytyrosol the main phenolic component on the water PLE olive leaves extracts, reaching up to 8.542
mg/g dried extract. On the other hand, oleuropein was the main component on the extracts obtained with ethanol (6.156–2.819
mg/g extract). Results described in this work demonstrate the good possibilities of using PLE as a useful technique for the valorization of by-products from the olive oil industry, such as olive leaves.
In this contribution, the performance of three different extraction procedures towards the extraction of antioxidants from rosemary (
Rosmarinus officinalis) is presented. Namely, pressurized liquid ...extraction (PLE), using water and ethanol as solvents, supercritical fluid extraction (SFE), using neat CO
2 and supercritical CO
2 modified with ethanol, as well as a novel extraction process called Water Extraction and Particle formation On-line (WEPO) are directly compared. Different extraction conditions including temperatures, times and pressures have been studied. The produced extracts have been characterized in terms of extraction yield, antioxidant activity (using the DPPH radical scavenging method) and total phenols (using the Folin method). Besides, all the extracts have been chemically characterized using a new quantitative UPLC-MS/MS method. This method allowed the determination of the main antioxidants present in rosemary, including, among others, rosmarinic acid, carnosic acid and carnosol, attaining detection limits as low as 2
ng/mL. The results obtained in this study show that PLE using ethanol at high temperatures (200
°C) was able to produce extracts with high antioxidant activity (EC
50 8.8
μg/mL) and high yield (ca. 40%) while efficiently extracting antioxidants of diverse polarity, among them, carnosic and rosmarinic acids, regarded as the most important antioxidants present in rosemary. Nevertheless, in this work, the ability of the three studied environmentally friendly extraction techniques to obtain bioactives from natural sources is demonstrated.
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