This reprint focuses on ecosystem observation, simulation and assessment. Ecosystems provide supply, regulation, culture and support services for human beings in addition to overall support human ...survival and sustainable development. However, driven by multiple factors such as climate change, population growth, urbanization, and exploitation of mineral resources, global problems such as ecosystem degradation and biodiversity loss have affected the sustainable development of human beings. Because of this, it has become a hot spot in ecology research to develop basic theories, model methods and technical means for ecosystem observation, simulation and evaluation for the quantitative analysis of the structure, process and function of ecosystems as well as the improvement of the scientific understanding of the changing characteristics and evolution laws of natural ecosystems.
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.
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.
With industrialization and urbanization, the competition among land production, living, and ecological (PLE) spaces has intensified. Particularly in ecological reserves, competition among various ...types of land use restricts the coordinated development of PLE space. To explore spatial sustainable development, this study starts from a PLE spatial perspective, based on Landsat long time series images. Object-based image analysis (OBIA) and landscape index analysis were selected to monitor the spatial and temporal land use and landscape pattern changes in the Poyang Lake region (PYL region) from 1989 to 2020. The RF-Markov-FLUS coupled model was used to simulate spatial changes in 2030 under four scenarios: production space priority (PSP), living space priority (LSP), ecological space priority (ESP), and an integrated development (ID). Finally, the goal-problem-principle was used to enhance PLE space. The results showed that: (1) production space and ecological spaces decreased in general from 1989 to 2020 by 3% and 7%, respectively; living space increased by 11%. (2) From 1989 to 2020, the overall landscape spread in the Poyang Lake (PYL) area decreased, connectivity decreased, fragmentation increased, landscape heterogeneity increased, and landscape geometry became more irregular. (3) Compared with the other three scenarios, the ID scenario maintained steady production space growth in 2030, the expansion rate of living space slowed, and the area of ecological space decreased the least. (4) Spatial pattern optimization should start with three aspects: the transformation of the agricultural industry, improving the efficiency of urban land use, and establishing communities of “mountains, water, forests, fields, lakes and grasses”. The results provide scientific planning and suggestions for the future ecological protection of Poyang Lake area with multiple scenarios and perspectives.
The continuous advances in technology cause innovation-acceptation-consolidationobsolescence flows regarding the knowledge and technology management strategies, both ad hoc and planned, of the ...corporations and also, in a different scale, of the individuals. Teaching and learning processes are not obviously unaware of this situation. The irruption of Information and Communication Technologies as educational tools mean both a conceptual and a methodological turning point in the way that institutions, educational or not, face training processes and learning management, especially with regard to the concept of distance education, which evolves, in a more or less significant way, when it adopts Internet as media; that is how the eLearning concept rises. However, from the first eLearning experiences, too much settled on the concept of platform or Learning Management System, up to the present times, there have been significant changes, again in both technological and methodological levels. It is important to underline, among others, the influence of social media in the daily habits of users. This way, an increased demand of learning personalization it is shown, as so as a complete connectivity with other peers, an unlimited access to resources and information sources, a complete flexibility in the way, place and time they access, and a natural and necessary coexistence of both formal and informal learning flows. Thus, the “traditional” eLearning platforms, despite their large penetration and consolidation, need to evolve and open themselves to support this rich fan of possibilities demanded by the users, ceasing to be the centre technological attention to become another component into a complex digital ecosystem oriented to the learning and knowledge management, both at institutional and personal levels. It is therefore necessary to make an updated review of the eLearning concept and its definitions that have been provided from the experience and perspective of our research group GRIAL (Research Group in InterAction and eLearning), coinciding with the tenth anniversary of the “Current status of e-learning systems” paper.
This study presents a novel vision of the brown seaweed
Durvillaea antarctica
aka ‘cochayuyo’ as an important food commonly consumed in Chile. ´Cochayuyo´ is a rich source of antioxidant and ...neuroprotective activity compounds demonstrated by evaluating the bioactivity associated with conventional and pressurized liquid extracts. Variables such as extraction yield, DPPH antioxidant assay, TEAC, and acetylcholinesterase (AChE) inhibitory capacity were studied employing Central Composite Design (CCD) based on a response surface methodology (RSM) and Pareto charts. Firstly, solvent polarity was evaluated by conventional extraction for the best antioxidant activity and they were employed in the experimental design (water/ethanol variations). Then, factors such as temperature (40–180 °C) and solvents (water/ethanol in 0, 50 to 100%) were selected resulting in CCD (12 total runs). In general, pressurized liquid extraction (PLE) improved the extraction yield and antioxidant activities compared to conventional extraction (twofold more using water). Moreover, PLE results showed that a higher yield (63.28%), was obtained with 50:50% water/ethanol at 180 °C. However, DPPH antioxidant assay was improved at the same temperature under 100% ethanol (EC
50
equal to 0.16 mg mL
−1
). For the neuroprotective activity,
D. antarctica
extracts were enriched under low-intermediate temperature (40–110 °C) and 100% water (IC
50
equal to 148.62 μg mL
−1
). After multiple response optimization, the best conditions to obtain antioxidant and neuroprotective extracts with high yield were 180 ºC and a ratio of 71:29 water:ethanol as extraction solvent. The results indicated that
D. antarctica
could be considered a functional food with significant antioxidant benefits and neuroprotective effects on human health.
•PLE+SAF of rosemary are proposed to provide two different polarity fractions.•Response surface methodology was used to optimize the separation conditions.•Rosmarinic acid was concentrated 2.7-fold ...in the raffinate, compared to the feed.•Enriched fractions with up to 47% carnosic acid+carnosol were obtained.•The optimum extract fraction showed 17% of HT-29 cell viability, after 24h.
Rosemary bioactivity is correlated with the presence of phenolic diterpenes (carnosic acid, carnosol) and phenolic acids (rosmarinic acid). In the present work, two processes, pressurized liquid extraction (PLE) and supercritical antisolvent fractionation (SAF) were integrated to separate and enrich these families of compounds. The optimization of the SAF process was carried out using a response surface methodology (RSM) with three factors: (i) CO2 pressure, (ii) percentage of water in the PLE extract and (iii) PLE extract/SC-CO2 flow ratio. The selected responses were the relative amount of each compound (rosmarinic acid (RA) and carnosic acid+carnosol (CA+CS)), total phenolic content, antioxidant activity and antiproliferative activity against HT-29 colon cancer cells. The higher CA+CS content was obtained at 100bar, 50% (v/v) of water in the feed solution and 0.025 feed/SC-CO2 mass flow ratio, achieving values of 478.1mg/g extract and 17% of cell survival after 24h of treatment.
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