Search results for: phenolic secondary metabolites

Authors: Jamerson Felipe Pereira Lima, Jeane Cecília Bezerra de Melo

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The difficulty and cost related to obtaining of protein tertiary structure information through experimental methods, such as X-ray crystallography or NMR spectroscopy, helped raising the development of computational methods to do so. An approach used in these last is prediction of tridimensional structure based in the residue chain, however, this has been proved an NP-hard problem, due to the complexity of this process, explained by the Levinthal paradox. An alternative solution is the prediction of intermediary structures, such as the secondary structure of the protein. Artificial Intelligence methods, such as Bayesian statistics, artificial neural networks (ANN), support vector machines (SVM), among others, were used to predict protein secondary structure. Due to its good results, artificial neural networks have been used as a standard method to predict protein secondary structure. Recent published methods that use this technique, in general, achieved a Q3 accuracy between 75% and 83%, whereas the theoretical accuracy limit for protein prediction is 88%. Alternatively, to achieve better results, support vector machines prediction methods have been developed. The statistical evaluation of methods that use different AI techniques, such as ANNs and SVMs, for example, is not a trivial problem, since different training sets, validation techniques, as well as other variables can influence the behavior of a prediction method. In this study, we propose a prediction method based on artificial neural networks, which is then compared with a selected SVM method. The chosen SVM protein secondary structure prediction method is the one proposed by Huang in his work Extracting Physico chemical Features to Predict Protein Secondary Structure (2013). The developed ANN method has the same training and testing process that was used by Huang to validate his method, which comprises the use of the CB513 protein data set and three-fold cross-validation, so that the comparative analysis of the results can be made comparing directly the statistical results of each method.

Keywords: artificial neural networks, protein secondary structure, protein structure prediction, support vector machines

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Authors: Isil Gazioglu, Abdulselam Ertas

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Aflatoxins (AFs) are secondary toxic metabolites of Aspergillus flavus and A. parasiticus. AFs can be absorbed through the skin. Potent carcinogens like AFs should be completely absent from cosmetics, this can be achieved by careful quality control of the raw plant materials. Regulatory limits for aflatoxins have been established in many countries, and reliable testing methodology is needed to implement and enforce the regulatory limits. In this study, ten medicinal plant samples (Bundelia tournefortti, Capsella bursa-pastoris, Carduus tenuiflorus, Cardaria draba, Malva neglecta, Malvella sharardiana, Melissa officinalis, Sideritis libanotica, Stakys thirkei, Thymus nummularius) were investigated for aflatoxin (AF) contaminations by employing an HPLC assay for the determination of AFB1, B2, G1 and G2. The samples were extracted with 70% (v/v) methanol in water before further cleaned up with an immunoaffinity column and followed by the detection of AFs by using an electrochemically post-column derivatization with Kobra-Cell and fluorescence detector. The extraction procedure was optimized in order to obtain the best recovery. The method was successfully carried out with all medicinal plant samples. The results revealed that five (50%) of samples were contaminated with AFs. The association between particular samples and the AF contaminated could not be determined due to the low frequency of positive samples.

Keywords: aflatoxin B1, HPLC-FLD, KOBRA-Cell, mycotoxin

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Authors: Ririn Lestari Sri Rahayu, Mustofa Ahda

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The use of synthetic antioxidants often causes a negative effect on health and increases the incidence of carcinogenesis. Development of the natural antioxidants should be investigated. However, natural antioxidants have a low toxicity and are safe for human consumption. Ethanol extract of mangosteen rind (Garcinia mangostana) contains natural antioxidant compounds that have various pharmacological activities. Antioxidants from the ethanol extract of mangosteen rind have free radicals scavenging activities. The scavenging activity of ethanol extract of mangosteen rind was determined by DPPH method. The phenolic compound from the ethanol extract of mangosteen rind is determined with Folin-Ciocalteu method. The results showed that the absolute ethanol extract of mangosteen rind has IC₅₀ of 40.072 ug/mL. The correlation of total phenols content with free radical scavenging activity has an equation y: 5.207x + 205.51 and determination value (R²) of 0.9329. Total phenols content from the ethanol extract of mangosteen rind has a good correlation with free radicals scavenging activity of DPPH.

Keywords: Antioxidant, Garcinia mangostana, Inhibition concentration 50%, Phenolic.

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Authors: Ilaisa Kacivakanadina, Samson Viulu, Brad Carte, Katy Soapi

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Two bioactive compounds namely Vulgamycin (also known as enterocin A) and 5-deoxyenterocin were purified from a marine bacterial strain 1903. Strain 1903 was isolated from marine sediments collected from the Solomon Islands. Morphological features of strain 1903 showed that it belongs to the genus Streptomyces. The two secondary metabolites were extracted using EtOAc and purified by chromatographic methods using EtOAc and hexane solvents. Mass spectrum and NMR data of pure compounds were used to elucidate the chemical structures. In this study, results showed that both compounds were strongly active against Wild Type Staphylococcus aureus (WTSA) (MIC < 1 µg/mL) and in Brine shrimp assays (BSA) (MIC < 1 µg/mL). 5-deoxyenterocin was also active against Rifamycin resistant Staphylococcus aureus (RRSA) (MIC, 250 µg/mL) while vulgamycin showed bioactivity against Methicillin resistant Staphylococcus aureus (MRSA) (MIC 250 µg/mL). To the best of our knowledge, this is the first study that showed the bio-activity of 5-deoxyenterocin. This is also the first time that Vulgamycin has been reported to be active in a BSA. There has not been any mechanism of action studies for these two compounds against pathogens. This warrants further studies on their mechanism of action against microbial pathogens.

Keywords: 5-deoxyenterocin, bioactivity, brine shrimp assay (BSA), vulgamycin

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Authors: Asma Temagoult, Bariza Zitouni, Yassin Noui

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Cactus fruit contains different nutritional and functional components, which are used because of their benefits to human health, such as flavonoids, phenolic compounds, carotenoids and vitamins C. It has hypoglycemic and hypolipidemic action, and antioxidant properties related to anticarcinogenic, antiulcerogenic and immunomodulatory effects. The antioxidant and nutritional properties have been characterized in cactus prickly pear (Opuntia ficus-indica Mill.), cultivar yellow, grown in Arris area; Eastern of Algeria. The antioxidant properties of this cactus cultivar were higher than the others cactus cultivar in the world. The amount of fruit phenolic compounds revealed contents between 20.65 and 45.70 mg / 100 g of FW for total polyphenols and 0.519 - 0.591 mg / 100 g of FW for the flavonoids. The antioxidant activity was evaluated by DPPH radical scavenging and FRAP (ferric reducing antioxidant power) methods. The average recorded to the potassium content is about 1070 mg / 100 g of the fresh weight; sodium is 60.7 mg / 100 g of the fresh weight and 80 mg / 100g for the calcium. According to the high value of this cactus, it was considered as a good nutrient and important pharmaceutical resource. It could be used as a natural additive or substituted food supplement in many foodstuffs production, to benefit from these benefits.

Keywords: antioxidant properties, DPPH, FRAP, nutritional properties, Opuntia ficus indica

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Authors: Eman Abdullah Morsi, Hend Okasha, Heba Abdel Hady, Mortada El-Sayed, Mohamed Abbas Shemis

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Context: Linum usitatissimum (Linn), known as Flaxseed, is one of the most important medicinal plants traditionally used for various health as nutritional purposes. Objective: Estimation of total phenolic and flavonoid contents as well as evaluate the antioxidant using α, α-diphenyl-β-picrylhydrazyl (DPPH), 2-2'azinobis (3-ethylbenzthiazoline-6-sulphonic acid (ABTS) and total antioxidant capacity (TAC) assay and investigation of anti-inflammatory by Bovine serum albumin (BSA) and anticancer activities of hepatocellular carcinoma cell line (HepG2) and breast cancer cell line (MCF7) have been applied on hexane, ethyl acetate, n-butanol and methanol extracts and also, fractions of methonal extract (hexane, ethyl acetate and n-butanol). Materials and Methods: Phenolic and flavonoid contents were detected using spectrophotometric and colorimetric assays. Antioxidant and anti-inflammatory activities were estimated in-vitro. Anticancer activity of extracts and fractions of methanolic extract were tested on (HepG2) and (MCF7). Results: Methanolic extract and its ethyl acetate fraction contain higher contents of total phenols and flavonoids. In addition, methanolic extract had higher antioxidant activity. Butanolic and ethyl acetate fractions yielded higher percent of inhibition of protein denaturation. Meanwhile, ethyl acetate fraction and methanolic extract had anticancer activity against HepG2 and MCF7 (IC50=60 ± 0.24 and 29.4 ± 0.12µg.mL⁻¹) and (IC50=94.7 ± 0.21 and 227 ± 0.48µg.mL⁻¹), respectively. In Gas chromatography-mass spectrometry (GC-MS) analysis, methanolic extract has 32 compounds, whereas; ethyl acetate and butanol fractions contain 40 and 36 compounds, respectively. Conclusion: Flaxseed contains totally different biologically active compounds that have been found to possess good variable activities, which can protect human body against several diseases.

Keywords: phenolic content, flavonoid content, HepG2, MCF7, hemolysis-assay, flaxseed

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Authors: Stephen Adeniyi Adefegha, Vitor Mostardeiro, Vera Maria Morsch, Ademir F. Morel, Ivana Beatrice Manica Da Cruz, Sabrina Somacal Maria Rosa Chitolina Schetinger

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Moringa stenopetala is often consumed as food and used in folkloric medicine for the management of several diseases. Purpose: This study was set up in order to assess the effect of aqueous extract of Moringa stenopetala on cell viability and oxidative stress biomarkers in BV-2 microglial cells. Aqueous extracts of M. stenopetala were prepared, lyophilized and reconstituted in 0.5% dimethylsulphoxide (DMSO). Cells were treated with M. stenopetala extracts (0.1 - 100 µg/ml) for cell viability and nitric oxide (NO) production tests. However, M. stenopetala extract (50 µg/ml) was used in the treatment of cells for the determination of protein carbonyl content and reactive oxygen species (ROS) level. Incubation of BV-2 microglia cell with M. stenopetala extract maintained cell viability, diminished NO and ROS levels, and reduced protein carbonyl contents Chlorogenic acid, rutin, kaempferol and quercetin derivatives were the main phenolic compounds identified in M. stenopetala leaf extract. These phenolic compounds present in M. stenopetala may be responsible for the mitigation of oxidative stress in BV-2 microglial cells.

Keywords: oxidative stress, BV-2 microglial cell, Moringa stenopetala, cell viability, antioxidant

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Authors: Meksem Nabila, Bordjiba Ouahiba, Meraghni Messaouda, Meksem Amara Leila, Djebar Mohhamed Reda

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The problems of protection of the cultures are being more and more important that they interest great number of farmers and scientists because of the excessive use of the organic phytosanitary products of synthesis that causes fatal damages on the environment. To reduce the inconveniences produced by these pesticides, the use of "biopesticides" originated from plants could be an alternative. The aim of this work is the valuation of a botanical species: Eucalyptus camaldulensis from Northeastern Algeria which extracts are supposed to have an antimicrobial activity, similar to pesticides. The extraction of secondary metabolites from the leaves of E. camaldulensis was realized using methanol and water, and measurements of total polyphenols were made by spectrometric method. Determination of the antimicrobial activity of the extracts at issue was realized in vitro on phyto-pathogenic fungal and bacterial stumps. Tests of comparison were included in the essays by using the chemical pesticidal products of synthesis. The obtained results show that the plant contains polyphenols with an efficiency mattering of the order of 22 %. These polyphenols have a strong fungicidal and bactericidal pesticidal activity against various microbial stumps and the values of the zones of inhibition are more important compared with that obtained in the presence of the chemicals of synthesis (fungicide).

Keywords: eucalyptus camaldulensis, biopesticide, polyphenols, antimicrobial activity

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Authors: Assia Amri, Naima Layachi, Ali Ladjama

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The characterization of some Algerian honey was carried out on the basis of their physico-chemical properties: moisture,hydroxy methyl furfural, diastase activity, pH,free, total and lactonic acidity, electrical conductivity, minerals and proline content. Studied samples are found to be low in moisture and therefore safe from fermentation, low in HMF level and high in diastase activity. Additionally the diastase activity and the HMF content are widely recognized parameters indicating the freshness of honey. Phenolic compounds present in honey are classified into two groups - simple phenols and polyphenols. The simple phenols in honey are various phenol acids, but polyphenols are various flavonoids and flavonides. The aim of our work was to determine antioxidant properties of various Algerian honey samples–the total phenol content, total flavonoids content, as well as honey anti radical activity.The quality of honey samples differs on account of various factors such as season, packaging and processing conditions, floral source, geographical origin and storage period. It is important that precautions should be taken to ensure standardization and rationalization of beekeeping techniques, manufacturing procedures and storing processes to improve honey quality.

Keywords: honey, physico-chemical characterization, phenolic coumpound, HMF, diastase activity

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Authors: Eny Syatriana

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English proficiency of Indonesian secondary school students is below standard. The low proficiency may come from poor teaching materials that do not meet the students’ need. The main objective for English teachers is to improve the English proficiency of the students. The purpose of this study is to explore the application Mapping, Practicing, Using (MPU) strategy with Instructional Materials Based on the School Curriculum toward the English achievement of Indonesian EFL Students. This paper is part my dissertation entitles 'Designing instructional materials for secondary school students based on the school curriculum' consisting of need analysis, design, development, implementation, and evaluation; this paper discusses need analysis and creates a model of creating instructional materials through deep discussion among teachers of secondary schools. The subject consisted of six English teachers and students of three classes at three different secondary schools in Makassar, South Sulawesi, Indonesia. Pretest and posttest design were administered to see the effectiveness of the MPU strategy. Questionnaires were administered to see the teachers and students’ perception toward the instructional materials. The result indicates that the MPU strategy is effective in improving the English achievement; instructional materials with different strategies improve the English achievement of the students. Both teachers and students argue that the presented instructional materials are effective to be used in the teaching and learning process to increase the English proficiency of the students.

Keywords: proficiency, development, English for secondary school students, instructional materials

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Authors: N. Meziou-Chebouti, A. Merabet, Y. Chebouti N. Behidj

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This work is a contribution to the knowledge of physicochemical characteristics of mature carob followed by evaluation of the activity, antimicrobial phenolics leaves and green pods of Ceratonia siliqua L. physicochemical study shows that mature carob it has a considerable content of sugar (50.90%), but poor in proteins (7%), fat (8%) and also has a high mineral content. The results obtained from phenolic extracts of leaves and green pods of Ceratonia siliqua L. show a wealth leaf phenolic extract especially flavonoids (0,545 mg EqQ/g) relative to the extract of green pods (0,226 mgEqQ/g). Polyphenols leaves have a slightly inhibitory effect on the growth of strains: Staphylococcus aureus, Escherichia coli, Klebsiella pneumoiae, Streptococcus sp and Sanmonella enteritidis, a strong inhibitory effect on the growth of Pseudomonas strain aerogenosa. Moreover, polyphenols pod have a slightly inhibitory effect on the growth of Streptococcus sp strains, Pseudomonas and aerogenosa Sanmonella enteritidis, a slightly inhibitory effect on the growth of Klebsiella pneumoniae strains, E. coli and Staphylococcus aureus.

Keywords: antimicrobial activity, bacteria, clove, Ceratonia siliqua, polyphenols

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Authors: Richard White, Anne Drabble, Maureen O’Neill

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The University of the Sunshine Coast (USC) offers secondary school students in the final two years of school (Years 11 and 12, 16 – 18 years of age) an opportunity to participate in a program which provides an accelerated pathway to tertiary studies. Whilst still at secondary school, the students undertake two first year university subjects that are required subjects in USC undergraduate degree programs. The program is called Integrated Learning Pathway (ILP) and offers a range of disciplines, including business, design, drama, education, and engineering. Between 2010 and 2014, 38% of secondary students who participated in an ILP program commenced undergraduate studies at USC following completion of secondary school studies. The research reported here considers “before and after” literacy and numeracy competencies of students to determine what impact participation in the ILP program has had on their academic skills. Qualitative and quantitative data has been gathered via numeracy and literacy testing of the students, and a survey asking the students to self-evaluate their numeracy and literacy skills, and reflect on their views of these academic skills. The research will enable improved targeting of teaching strategies so that students will acquire not only course-specific learning outcomes but also collateral academic skills. This enhancement of academic skills will improve undergraduate experience and improve student retention.

Keywords: academic skills enhancement, accelerated pathways, improved teaching, student retention

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Authors: Amenaghawon Clement Osemwinyen

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The Activity, Student-centred, Experiment, Improvisation - Plan, Do, See, Improve (ASEI-PDSI) method championed by the Strengthening Mathematics And Science Education (SMASE) - Nigeria Project is an attempt to improve the quality of mathematics, which has consistently declined over the years in both public primary and secondary schools across the country. The study thus assessed the ASEI-PDSI method on students’ attitudes and achievement in junior secondary schools (JSS) mathematics in FCT-Abuja. A survey research design was adopted, and 100 mathematics teachers using a stratified random sampling method were used for the study. The data were collected using structured questionnaires and analyzed using descriptive statistics. The findings showed that the ASEI-PDSI method had significantly improved the attitudes of students toward mathematics. The study also revealed that the ASEI-PDSI method significantly influenced junior secondary school (JSS) students’ mathematics achievement. Amongst the recommendations were that teachers should be encouraged to adopt the ASEI-PDSI method in teaching and learning mathematics in order to create a mathematically stimulating classroom environment which could advertently influence junior secondary school (JSS) students’ attitude and academic performance in mathematics. Also, regular in-service training programs should be organized by stakeholders (government and other interest groups) so as to improve the teaching strategies of teachers, mostly as they affect the ASEI-PDSI method.

Keywords: achievement, ASEI-PDSI method, attitude, mathematics, SMASE

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Authors: Asadullah Sheikh, Kerry Barnett, Paul Ayres

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Despite significant progress in access, equity and public examination success, poor student performance in mathematics in secondary schools has become a major concern in Bangladesh. A substantial body of research has emphasised the important contribution of teaching practices to student achievement. However, this has not been investigated in Bangladesh. Therefore, the study sought to find out the effectiveness of mathematics teaching practices as a means of improving secondary school mathematics in Dhaka Municipality City (DMC) area, Bangladesh. The purpose of this study was twofold, first, to identify the 20 highest performing secondary schools in mathematics in DMC, and second, to investigate the teaching practices of mathematics teachers in these schools. A two-phase mixed method approach was adopted. In the first phase, secondary source data were obtained from the Board of Intermediate and Secondary Education (BISE), Dhaka and value-added measures used to identify the 20 highest performing secondary schools in mathematics. In the second phase, a concurrent mixed method design, where qualitative methods were embedded within a dominant quantitative approach was utilised. A purposive sampling strategy was used to select fifteen teachers from the 20 highest performing secondary schools. The main sources of data were classroom teaching observations, and teacher interviews. The data from teacher observations were analysed with descriptive and nonparametric statistics. The interview data were analysed qualitatively. The main findings showed teachers adopt a direct teaching approach which incorporates orientation, structuring, modelling, practice, questioning and teacher-student interaction that creates an individualistic learning environment. The variation in developmental levels of teaching skill indicate that teachers do not necessarily use the qualitative (i.e., focus, stage, quality and differentiation) aspects of teaching behaviours effectively. This is the first study to investigate teaching behaviours of effective secondary mathematics teachers within Dhaka, Bangladesh. It contributes in an international dimension to the field of educational effectiveness and raise questions about existing constructivist approaches. Further, it contributes to important insights about teaching behaviours that can be used to inform the development of evidence-based policy and practice on quality teaching in Bangladesh.

Keywords: effective teaching, mathematics, secondary schools, student achievement, value-added measures

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Authors: I. Mnafeg, A. Abichou, L. Beji

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Traditional mechanical control systems in thrust vectoring are efficient in rocket thrust guidance but their costs and their weights are excessive. The fluidic injection in the nozzle divergent constitutes an alternative procedure to achieve the goal. In this paper, we present a 3D analytical model for fluidic injection in a supersonic nozzle integrating an orifice. The fluidic vectoring uses a sonic secondary injection in the divergent. As a result, the flow and interaction between the main and secondary jet has built in order to express the pressure fields from which the forces and thrust vectoring are deduced. Under various separation criteria, the present analytical model results are compared with the existing numerical and experimental data from the literature.

Keywords: flow separation, fluidic thrust vectoring, nozzle, secondary jet, shock wave

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Authors: Mariam Mojally, Randa Abdou, Wisal Bokhari, Sultan Sab, Mohammed Dawoud, Amjad Albohy

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Secondary metabolites produced by endophytes are an excellent source of biologically active compounds. In our current study, we evaluated terezine E and 14-hydroxyterezine D for binding to the active site of histone deacetylase (PDB ID: 4CBT) and matrix metalloproteinase 9 (PDB ID: 4H3X) by molecular docking using AutoDock Vina software after having tested their cytotoxic activities on three cell lines (human ductal breast epithelial tumor cells (T47D)-HCC1937), human hepatocarcinoma cell line (HepG2)-HB8065), and human colorectal carcinoma cells (HCT-116)-TCP1006, purchased from ATCC, USA)). Additionally, their antimicrobial activities were investigated, and their minimum inhibitory concentration (MIC) values were determined against P. notatum and S. aureus by the broth microdilution method. Higher cytotoxicity was observed for terezine E against all tested cell lines compared to 14-hydroxyterezine D. Molecular docking results supported the high cytotoxicity of terezine E and showed higher binding affinity with 4CBT with an energy score of 9 kcal/mol. Terezine E showed higher antibacterial and antifungal activities than 14-hydroxyrerezine D: MIC values were 15.45 and 21.73 mg/mL against S. aureus and 8.61 and 11.54 mg/mL against P. notatum, respectively

Keywords: Terezine E, 14-Hydroxyterezine D, cytotoxicity, antimicrobial activity, molecular docking

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Authors: Sakinah Abdullah, Rosna Mat Taha

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Antioxidants are compounds that protect cells against the damaging effects of reactive oxygen species such as singlet oxygen, superoxide, peroxyl radicals, and peroxynitrite which result in oxidative stress leading to cellular damage. Natural antioxidant are in high demand because of their potential in health promotion and disease prevention and their improved safety and consumer acceptability. Plants are rich sources of natural antioxidant. Dioscorea alata L. known as 'ubi badak' in Malaysia were well known for their antioxidant content, but this plant was seasonal. Thus, tissue culture technique was used to mass propagate this plant. In the present work, a comparative study between in vitro (from tissue culture) and in vivo (from intact plant) samples of Dioscorea alata L. for their antioxidant potential by 2,2-diphenil -1- picrylhydrazyl (DPPH) radical scavenging activity method and their total phenolic and flavonoid contents were carried out. All samples had better radical scavenging activity but in vivo samples had the strongest radical scavenging activity compared to in vitro samples. Furthermore, tubers from in vivo samples showed the greatest free radical scavenging effect and comparatively greater phenolic content than in vitro samples.

Keywords: Dioscorea alata, tissue culture, antioxidant, in vivo, in vitro, DPPH

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Authors: Mateus L. O. Freitas, Flávia H. de M. Libório, Letycia L. Ricardo, Patrícia da C. Zonetti, Graciene de S. Bido

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Weeds compete with agricultural crops for resources such as light, water, and nutrients. This competition can cause significant damage to agricultural producers, and, currently, the use of agrochemicals is the most effective method for controlling these undesirable plants. Morning glory (Ipomoea grandifolia [Dammer] O'Donell) is an aggressive weed and significantly reduces agricultural productivity making harvesting difficult, especially mechanical harvesting. The biggest challenge in modern agriculture is to preserve high productivity reducing environmental damage and maintaining soil characteristics. No-till is a sustainable practice that can reduce the use of agrochemicals and environmental impacts due to the presence of plant residues in the soil, which release allelopathic compounds and reduce the incidence or alter the growth and development of crops and weeds. Sorghum (Sorghum bicolor [L.] Moench) is a forage with proven allelopathic activity, mainly for producing sorgholeone. In this context, this research aimed to evaluate the allelopathic action of sorghum fractions using hexane, dichloromethane, butanol, and ethyl acetate on the germination and initial growth of morning glory. The parameters analyzed were the percentage of germination, speed of germination, seedling length, and biomass weight (fresh and dry). The bioassays were performed in Petri dishes, kept in an incubation chamber for 7 days, at 25 °C, with a 12h photoperiod. The experimental design was completely randomized, with five replicates of each treatment. The data were evaluated by analysis of variance, and the averages between each treatment were compared using the Scott Knott test at a 5% significance level. The results indicated that the dichloromethane and ethyl acetate fractions showed bioherbicidal effects, promoting effective reductions on germination and initial growth of the morning glory. It was concluded that allelochemicals were probably extracted in these fractions. These secondary metabolites can reduce the use of agrochemicals and environmental impact, making agricultural production systems more sustainable.

Keywords: allelochemicals, secondary metabolism, sorgoleone, weeds

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Authors: Iniye Irene Wodi, Kennedy B. Gibson

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Students’ poor performance in mathematics in both internal and external examinations has been a source of concern to researchers in Nigeria. The cause of this has been attributed to both teachers and students. To this end, this study sought to find out students’ perceptions of teachers’ attributes as a cause of mathematics phobia among secondary school students in Bayelsa State Nigeria. The population of the study comprised of all students of senior secondary schools in Yenagoa metropolis. A sample of 120 students was drawn from this population using clustering and simple random sampling techniques. The instrument for data collection was a researcher constructed questionnaire titled Mathematics Phobia Questionnaire (MPQ). Data were analysed, and the results revealed that students perceived teachers’ attributes such as methods and styles of teaching, difficulty in communication, etc. as causes of mathematics phobia among students in senior secondary schools in Bayelsa State. Based on the result, it was therefore recommended that mathematics teachers should be retrained periodically in order to learn new and innovative ways of teaching mathematics to prevent its phobia among students.

Keywords: mathematics phobia, teacher attributes, teaching method, teaching style

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Authors: Sita Yiemkuntitavorn

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The purposes of this research were to: (1) Develop a distance training package on the teaching principles foundation english language in order to gain the teaching ability for secondary school english teachers in Bangkok and its vicinity (2) study the satisfaction of English teachers towards the quality of a distance training package. The samples for the efficiency testing consisted of 30 english teachers in Bangkok and its vicinity, obtained by purposive sampling. Research tools comprised (1) a distance learning package on the foundation of English writing for teachers. (2) The questionnaires asking the teachers on the quality of the distance training package, and (3) two parallel forms of an achievement test for pre-testing and post-testing. Statistics used were the E1/E2 index, mean and standard deviation. Research findings showed that, (1) the distance training package were efficient at 80.2/80.6 according to the set efficiency criterion of 80/80; (2) and the satisfaction of the teachers on the distance training package of the teaching principles of foundation english for secondary school english teachers in Bangkok and its vicinity was at “Satisfied” level.

Keywords: a distance training package, teaching principles of foundation english, secondary school, Bangkok and its vicinity

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Authors: Imen Abid, Rachel Calvet, Michel Baltas

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Flavonoids are secondary metabolites that belong to a polyphenolic class, present in fruits and vegetables, playing a significant role in biological systems. The structural variations of these flavonoids are associated with many biological and pharmacological activities (antioxidant, anti-inflammatory, anticancer, antibacterial, antifungal, antiviral, and antimalarial). Given their importance in plants and health-promoting roles in humans, significant efforts have been devoted towards their isolation of flavonoids and chemical elaboration (organic synthesis). But with the increasing public concern over environmental degradation and future resources, it is of great importance for chemists to come up with different approaches, less hazardous to human health and the environment. Being employed in large amounts, the solvents used in organic synthesis are high on the list of environmental pollutants. To overcome these problems, our approach is to develop unconventional processes involving solvent-free conditions. The application of mechanical forces to solvent-free or solvent-less reaction mixtures through the use of ball mills offers many advantages over traditional solvent-based strategies. It is one of the unconventional activation methods, which makes it possible to overcome the use of solvents, in the context of green chemistry and more respectful of the environment.

Keywords: organic synthesis, green chemistry, mecanochemistry, pharmaceutical molecules

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Authors: S. N. Al-Bahry, Y. M. Al-Wahaibi, S. J. Joshi, E. A. Elshafie, A. S. Al-Bimani

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Oman is one of the oil producing countries in the Arabian Peninsula and the Gulf region. About 30-40 % of oil produced from the Gulf is transported globally along the seacoast of Oman. Oil pollution from normal tanker operations, ballast water, illegal discharges and accidental spills are always serious threats to terrestrial and marine habitats. Due to Oman’s geographical location at arid region where the temperature ranges between high 40s and low 50s Celsius in summers with low annual rainfall, the main source of fresh water is desalinated sea and brackish water. Oil pollution, therefore, pose a major threat to drinking water. Biosurfactants are secondary metabolites produced by microorganisms in hydrophobic environments to release nutrients from solid surfaces, such as oil. In this study, indigenous oil degrading thermophilic spore forming bacteria were isolated from oil fields contaminated soil. The isolates were identified using MALDI-TOF biotyper and 16s RNA. Their growth conditions were optimized for the production of biosurfactant. Surface tension, interfacial tensions and microbial oil biodegradation capabilities were tested. Some thermophilic bacteria degraded either completely or partially heavy crude oil (API 10-15) within 48h suggesting their high potential in oil spill bioremediation and avoiding the commonly used physical and chemical methods which usually lead to other environmental pollution.

Keywords: bacteria, bioremediation, biosurfactant, crude-oil-pollution

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Authors: Christiana Fwenji Zumyil, Toma Maina Antip

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Environmental Science subject is currently not an independent subject taught in secondary schools in Nigeria like Biology, Agricultural Science, Chemistry, Geography and other subjects that students take final exams (West Africa Examination Council, WAEC, National Examination Council, NEC, National Board for Technical Education, NABTED)., on it but its elements/topics/contents are integrated into the curriculum of the subjects mentioned, and because of that, it becomes difficult to know what should be taught and how it should be taught. Currently, it is still difficult to implement student-centered strategies in the classroom. Through this study, we sought to diagnose the difficulties, advantages and perceptions that Environmental Teachers experience when conceiving and implementing Science-Technology-Society (STS) strategies in SS2 classes at the Secondary Education level. Four semi-structured interviews were conducted with Secondary School Environmental Teachers. Despite the difficulties found, the advantages, the motivation and the involvement of the students that this teaching perspective enables to lead the teacher to continue developing and implementing STS strategies in the classroom.

Keywords: environment, science, technology, society, science-technology-society, science education, secondary teaching

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Authors: S. Yakubu, E. A. Isah

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One of the objectives of the school discipline policy is to instill discipline among students. However, despite the availability of this policy in various secondary schools in Nigeria, there seem to be numerous cases of indiscipline among students, which has become a source of concern to all stakeholders in the education sector. In an attempt to proffer possible solutions to this unending challenge, the study investigated the influence of knowledge and attitude on compliance of secondary school students towards school discipline policy in Ibadan North Local Government Area of Oyo State, Nigeria. The descriptive survey research design was employed to collect the requisite data. The multi-stage sampling procedure was adopted to select 570 respondents as the sample for the study. The data collected were analyzed using statistical measures of Mean, Standard deviation and Pearson Product Moment Correlation. The findings of the study showed that knowledge and compliance of school discipline policy among secondary school students in Ibadan North Local Government Area of Oyo State were significantly related (r =0.330, p<0.05). The study also revealed a significant relationship between attitude and compliance of school discipline policy among secondary school students in Ibadan North Local Government Area of Oyo State (r = 0.593, p<0.05). Based on the findings, it was recommended that school rules and regulations should be emphasized and given more awareness for easy compliance. Also, students should be encouraged to portray a positive attitude towards their respective rules and regulations.

Keywords: knowledge, attitude, compliance, school discipline policy

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Authors: Javier Donoso-Bravo, Camila Cortés-Zambrano

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In this paper, we analyze socioterritorial inequalities in the region of Valparaiso (Chile) using secondary data to account for these inequalities drawing on economic, social, educational, and environmental dimensions regarding the thirty-six municipalities of the region. We looked over a wide-ranging set of secondary data from public sources regarding economic activities, poverty, employment, income, years of education, post-secondary education access, green areas, access to potable water, and others. We found sharp socioterritorial inequalities especially based on the economic performance in each territory. Analysis show, on the one hand, the existence of a dual and unorganized development model in some territories with a strong economic activity -especially in the areas of finance, real estate, mining, and vineyards- but, at the same time, with poor social indicators. On the other hand, most of the territories show a dispersed model with very little dynamic economic activities and very poor social development. Finally, we discuss how socioterritorial inequalities in the region of Valparaiso reflect the level of globalization of the economic activities carried on in every territory.

Keywords: socioterritorial inequalities, development model, Chile, secondary data, Region of Valparaiso

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Authors: Z. H. Shi, T. J. Dou, H. Zhang, H. X. Huang, N. Zeng

Abstract:

The contamination of significant quantities of soils and sediments with uranium and other actinide elements as a result of nuclear activity poses many environmental risks. The electrokinetic process is one of the most promising remediation techniques for sludge, sediment, and saturated or unsaturated soils contaminated with heavy metals and radionuclides. However, secondary waste is a major concern for soil contaminated with nuclides. To minimize the generation of secondary wastes, this study used the anion and cation exchange membranes to improve the performance of the experimental apparatus. Remediation experiments of uranium-contaminated soil were performed with different agents. The results show that using acetic acid and EDTA as chelating agents clearly enhances the migration ability of the uranium. The ion exchange membranes (IEMs) used in the experiments not only reduce secondary wastes, but also, keep the soil pH stable.

Keywords: electrokinetic remediation, ion exchange membranes, soil, uranium

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Authors: M. E. Ali Mohsin, Agus Arsad, Othman Y. Alothman

Abstract:

This study explains the influence of secondary filler on the dispersion of carbon nanotube (CNT) reinforced high density polyethylene (HDPE) nanocomposites (CNT/HDPE). In order to understand the mixed-fillers system, Montmorillonite (MMT) was added to CNT/HDPE nanocomposites. It was followed by investigating their effect on the thermal, mechanical and morphological properties of the aforesaid nanocomposite. Incorporation of 3 wt% each of MMT into CNT/HDPE nanocomposite resulted to the increased values for the tensile and flexural strength, as compared to the pure HDPE matrix. The thermal analysis result showed improved thermal stability of the formulated nanocomposites. Transmission electron microscopy (TEM) images revealed that larger aggregates of CNTs were disappeared upon addition of these two components leading to the enhancement of thermo-mechanical properties for such composites.

Keywords: secondary filler, montmorillonite, carbon nanotube, nanocomposite

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Authors: Egbo Anthonia Chinonyelum

Abstract:

This study was designed to identify the extent of the influence of vocational guidance services on career choice of secondary school students in Enugu State. The study was guided by two research questions and two null hypotheses tested at 0.05 level of significance. A sample of 1,054 respondents made of teachers, students and counsellors drawn from the 34 secondary schools from the six educational zones of Enugu State Nigeria was used for the study. The researcher administered the research instruments generated from the randomly selected senior secondary schools from the six educational zones in Enugu State. The data collected from the respondents were analyzed using mean statistics drawn from the responses of senior secondary school students, counsellor and teacher to the questionnaire item. Four point scale was used to measure the opinion of the respondents, such that after the statistical analysis, those items in the questionnaire that have the mean rate of 2.5 and is of great level of influence on the career choice of students. While questionnaire item with the mean below 2.5 were taken as having little extent of influence on career choice of students. The findings in this work showed that there was little extent on the influence of vocational guidance on career choice, choice of subjects and positive attitude of students towards vocational guidance. Based on the findings the researcher recommended that government and other relevant authorities should help by creating the awareness of vocational guidance programme in Schools.

Keywords: vocation, guidance, counselling, services, career, choice

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Authors: Teng-Chiu Lin, Pei-Jen Lee Shaner, Shin-Yu Lin

Abstract:

Both forest age and physical damages due to weather events such as tropical cyclones can influence forest characteristics and subsequently its capacity to sequester carbon. Detangling these influences is therefore a pressing issue under climate change. In this study, we compared the compositional and structural characteristics of three forests in Taiwan differing in age and severity of typhoon disturbances. We found that the two forests (one old-growth forest and one secondary forest) experiencing more severe typhoon disturbances had shorter stature, higher wood density, higher tree species diversity, and lower typhoon-induced tree mortality than the other secondary forest experiencing less severe typhoon disturbances. On the other hand, the old-growth forest had a larger amount of woody debris than the two secondary forests, suggesting a dominant role of forest age on woody debris accumulation. Of the three forests, only the two experiencing more severe typhoon disturbances formed new gaps following two 2015 typhoons, and between these two forests, the secondary forest gained more gaps than the old-growth forest. Consider that older forests generally have more gaps due to a higher background tree mortality, our findings suggest that the age effects on gap dynamics may be reversed by typhoon disturbances. This study demonstrated the effects of typhoons on forest characteristics, some of which could negate the age effects and rejuvenate older forests. If cyclone disturbances were to intensity under climate change, the capacity of older forests to sequester carbon may be reduced.

Keywords: typhoon, canpy gap, coarse woody debris, forest stature, forest age

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Authors: Daniel Motlhanka, Neo Kerebotswe

Abstract:

The strong and long history of use of medicinal plants in Botswana to address existing and emerging health threats provides undebatable evidence for their potential as innovative therapeutic tools. The prevalence of emerging health threats, such as COVID-19 and hard-to-treat non-communicable diseases, warrants the scientific community to revisit and exploit ethnopharmacology for its potential as a source of therapeutic tools. Many studies conducted on bioactivity-guided bioassays of ethnobotanical resources have proved a number of health beneficial properties of these plants, such as free radical scavenging, anti-inflammatory, antimicrobial and, most importantly, the capability of medicinal plants to alleviate oxidative stress. In this work, a number of medicinal plants used in Botswana traditional medicine were investigated for both their free radical scavenging capability and total phenolic contents using the Free Radical Scavenging Power (FRSP) and Folin Ciocalteau (FC) method. At 100 micrograms/ml all the studied plants expressed above 90% Scavenging power and expressed total phenolic contents between 5000- 8890 mg/L.GAE. These plants are promising tools for engineering active therapeutic tools against life-threatening diseases of oxidative stress origin.

Keywords: oxidative stress, non-communicable diseases, total phenolics, ethnobotanicals

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