In recent months, universities around the world have been forced to cancel courses and close their doors due to the growing coronavirus epidemic. Following the government’s precautions, Algerian students were bound to quarantine regulations for their safety. Thus, they unexpectedly switched to online learning instead of face-to-face learning. Our objective of this exploratory study is to investigate the perceptions of Algerian university students regarding the abrupt transition to online learning amid the COVID-19 pandemic. To achieve this goal, an online survey with closed and open-ended questions was conducted among 380 students from the faculty of chemistry and hydrocarbons (FCH) at the University of BoumerdesAlgeria. The results showed that students have a negative perception of online learning. They are reluctant about this new digital pedagogy and prefer the traditional way of teaching to online teaching during the coronavirus pandemic.
Any plant with a vascular system has a specific endophytic microflora. The identification of bacteria is essential in plant pathology. Although identification methods are effective, they are costly and time consuming. The purpose of this work is to isolate and to identify the different bacteria from the internal tissues of Urtica dioica L. and to study their diversity. This last is based on the different parts of the plant (stems, leaves and roots) and the harvest regions (Dellys and Tlamcen). The identification of bacteria is done by biochemical tests and confirmed by MALDI-TOF MS. Seven genus and eleven species were isolated from the Great Nettle. They belong to the genera Bacillus, Escherichia, Pantoea, Enterobacter, Staphylococcus, Enterococcus and Paenibacillus. The majority of these bacteria were isolated from Tlemcen which makes this region the richest in endophytic bacteria compared to that harvested from Dellys. The results show also that the leaves are the most diversified in endophytic bacteria. Bacillus pumilus-ME is the common species of the three parts of the plant harvested in both regions. From this work, it emerges that the Great Nettle can be settled by various endophytic bacteria which are differently distributed within the same plant harvested in different regions.
This work aims for the phytochemical study and evaluation of the antioxidant activity of phenolic compounds and essential oils of medicinal plant Pistacia lentiscus L. quantitatively and qualitatively. Through the results obtained, it appears that the leaves and fruits are rich in substances with a high antioxidant power. The yield of the phenolic compounds obtained from 10g to powder of plant is for leaves 116.49 % and 61.34 % for fruit. For essential oils, it is 0.253 ± 0.131 % for 100 g of plant material. The chromatographic profile of the essential oil of Pistacia lentiscus L. shows that monoterpenes are the major compound (9.675 % of identified molecules). The strong antioxidant activity of extracts obtained only confirms the traditional use of this plant by the local population.
Introduction. The natural plant resources are products with high added value, used in various fields for the manufacture of a wide variety of products. Objective. The purpose of this study was the physicochemical and chromatographic characterization of Ziziphus jujuba seeds vegetable oil, and the evaluation of their antioxidant and anti-inflammatory activity. Material and methods. Seeds oil extraction was done by soxhlet. Fatty acid content was determined by gas chromatography (GPC). Organoleptic and physicochemical characteristics were determined, and antioxidant activity was evalua-ted by diphenyl-picryl-hydrazyl (DPPH) test and -carotene bleaching. Anti-inflam-matory activity was essayed using carrageenan-induced plantar edema model in mice. Results. Extracted seeds oil had an extraction yield of 3.4%. GPC characterization sho-wed the presence of 12 fatty acids with a predominance of oleic acid (47.02%), and linoleic acid (37.40%). Physicochemical parameters of Ziziphus jujuba seeds oil showed an acidity of 2.05%, a saponification value of 198.17 mg KOH/mL, and refractive index of 1.471±0.00. This oil expressed a significant antiradical activity for the DPPH test, and low for that of β-carotene. In vivo study of edema induction in mice showed that oil had a maximum effective effect in inhibiting oedema (55.89±0.03%), at the first hour, compared to Diclofenac (19.88±0.12%), at the same hour. Conclusion. These results highlight the fatty acids richness of Ziziphus jujuba seeds oil with antioxidant and anti-inflammatory effects. These properties make it possible to predict its use in biotech-nology and cosmetology. [Introduction. Les ressources naturelles végétales sont des produits à forte valeur ajoutée, utilisés dans divers domaines pour la fabrication d’une large variété de produits. Objectif. Le présent travail a pour but la caractérisation physico-chimique et chromatographique de l’huile végétale des graines de Ziziphus jujuba Mill., et l’évaluation de leur activité antioxydante et anti-inflammatoire. Matériel et méthodes. L’huile des graines extraite par soxhlet est caractérisée sur le plan organoleptique et physicochimique. La teneur en acides gras est déterminée par une analyse chromato-graphique en phase gazeuse (CPG). L’activité antioxydante est évaluée par le test diphe-nyl-picryl-hydrazyl (DPPH) et le test de blanchiment. L’activité anti-inflammatoire est déterminée à l’aide du modèle de l’œdème plantaire induit chez la souris par la carra-génine. Résultats. L’huile présente un rendement d’extraction de 3,14%. La caracté-risation par la CPG montre la présence de 12 acides gras avec une prédominance de l’acide oléique (47,02%) et l’acide linoléique (37,40%). Les paramètres physico-chimi-ques ont montré une acidité de 2,05%, un indice de saponification de 198,17mg KOH/mL, un indice de réfraction de 1,471±0,00. L’huile végétale testée exprime une activité anti-radicalaire importante pour le test de DPPH et forte pour celui de β-carotène. L’induction d’œdème chez les souris a montré un effet efficace maximal de l’huile dans l’inhibition de l’œdème à la première heure, par rapport au Diclofénac à la même heure. Conclusion. Les résultats de cette étude font ressortir la richesse de l’huile des graines de Ziziphus jujuba en acides gras dotés d’un effet antioxydant et anti-inflammatoire. Ces propriétés permettent de prévoir son utilisation en biotechnologie et en cosmétologie.]
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