http://depot.umc.edu.dz/handle/123456789/1 2026-11-01T19:11:02Z 2026-11-01T19:11:02Z Boukabache, Meriem Chibani, Salih http://depot.umc.edu.dz/handle/123456789/14866 2026-10-20T14:25:50Z 2025-01-09T00:00:00Z

Phytochemical study and biological activities of two species from the families verbenaceae and lauraceae. Boukabache, Meriem; Chibani, Salih Synthetic chemicals can have harmful effects on both humans and plants, leading to health issues like toxicity and pollution that disrupt ecosystems and damage plant growth; meanwhile essential oils offer safer, and natural alternatives. In this context, the objective of this research was to study the chemical composition, as well as the antioxidant, anti-enzymatic, and insecticidal activities, of essential oils from two medicinal plants, Laurus nobilis and Aloysia citrodora, along with their major compounds: 1,8-cineole, methyleugenol, citral, and limonene. The analysis of the chemical composition of the essential oils was carried out by gas chromatography-mass spectrometry (GC-MS). Six different in vitro tests, DPPH scavenging, ABTS cation radical, reducing power, β-carotene/linoleic acid bleaching, cupric reducing antioxidant capacity, and phenanthroline assay were performed to evaluate the antioxidant properties of Laurus nobilis, Aloysia citrodora essential oils, and their major compounds; furthermore, the antienzymatic activity was carried out against six enzymes: acetylcholinesterase, butyrylcholinesterase, tyrosinase, urease, α-glucosidase, and α-amylase. The insecticidal potential of essential oils, and their major compounds was assessed against three Aphid’s species: Aphis fabae, Rhopalosiphum maidis, and Myzus persicae. We employed three different methods: contact toxicity, fumigant toxicity, and field efficacy testing. The results of the chemical composition analysis showed that Laurus nobilis essential oil is primarily composed of 1,8-cineole (26.43%), methyleugenol (13.55%), α-Terpinyl Acetate (11.77%), and linalool (10.19 %). In contrast, the main constituents of Aloysia citrodora essential oil were found to be citral (13.80%), limonene (12.16%), Neral (10.67%), Bicyclogermacrene (10.03%), Isospathulenol (6.06%), caryophyllene oxide (6.82%) and p-cymene (4.5%). the results of antioxidant activity, demonstrated that L. nobilis essential oil, along with 1,8-cineole and methyleugenol, exhibited strong antioxidant properties across all test methods. In contrast, A. citrodora essential oil and its major compounds, citral and limonene, showed no antioxidant activity. The assessment of enzymatic inhibition revealed that the examined volatile plant extracts, and their primary constituents exhibited selective efficacy, demonstrating potent inhibitory effects on certain enzymes while remaining inert against others. The insecticidal activity data indicates that both essential oils, along with the major compounds, showed strong contact and fumigant toxicities, against A. fabae, R. maidis, and M. persicae. Field experiments showed that Laurus nobilis essential oil had significant control effects, at a concentration of 0.4 L/m² achieving 86.81%, 80.67%, and 78.23% mortality for A. fabae, R. maidis, and M. persicae, respectively. Similarly, Aloysia citrodora essential oil shows mortality of 90.33% in adults of M. persicae, followed by 86.67% in A. fabae, and 84.00 % in R. maidis. However, the toxicity varied based on insect species, concentration, and exposure duration. Both oils proved more potent than their individual compounds in all the biological activities tested. The results showed that these essential oils and their major compounds could serve as alternatives to chemical synthetic preservatives and pesticides.

2025-01-09T00:00:00Z Maou, Zakarya Bougherara, Ahmed http://depot.umc.edu.dz/handle/123456789/14865 2026-10-20T14:15:15Z 2024-11-18T00:00:00Z

Les Ziban : durabilité des effets des aménagements hydrauliques et atténuation des risques d’inondation et de sècheresse. Maou, Zakarya; Bougherara, Ahmed The Ziban, located in the extreme North-east of the Sahara in an arid climate (rainfall below 150 mm/year), benefit from the waters of the Septentrional Sahara Aquifer System (SASS) and surface run-off from the southern flank of the Saharan Atlas (Oued Labiod, Abdi, El-Hai, Larab and Oued Djedi). This situation provides them with significant and diversified water resources (groundwater and surface water), which have given rise to a number of Oases that have shown unrivalled agricultural dynamism in recent decades. Today, however, surface water only accounts for 7 % (82 Hm3 /year) of mobilized water resources. Nevertheless, their inflow has ensured the recharging of aquifers, particularly groundwater tables, which has supplied and continues to supply the city of Biskra with drinking water. Groundwater resources account for 98 % (1124, 24 Hm3/year) of mobilized water resources. Today, the rate of abstraction imposed by the expansion of developed areas (1040 ha/year) has led to a significant reduction in water levels and a deterioration in the quality of the resource. In this context, the impact of man’s action can aggravate the imbalance or mitigate the contradictions and promote the resilience of a rapidly developing region. In addition, the Foum El Gherza dam, 80 % silted up, no longer ensures flood control, hence the reappearance, after decades, of the risk of flooding in its downstream section (towns and agriculture). However, the impoundment of the fountain of the Gazelles and Bouzina dams (2000 and 2021) has dried up the Oueds El-Hai and Abdi, which were responsible for recharging the groundwater downstream. However, the planned underground dam (Ouled Djellal) remains the most suitable for hydro-morphological conditions and is perfectly suited to the harsh conditions of arid zones. To support the current pace of development, it has become inevitable to connect the Ziban to other regional sources. To this end, two water transfer projects have been adopted, a supply from the Albien at Touggourt and a drinking water supply from the Beni Haroun transfer system (Koudiet Medaouar dam). This strategy can only guarantee the resilience of the Ziban region.

2024-11-18T00:00:00Z Touil, Abderrahim Babaa, Fatima http://depot.umc.edu.dz/handle/123456789/14864 2026-10-20T10:50:58Z 2024-12-23T00:00:00Z

Diagnostic des defauts de roulements dans les machines electriques. Touil, Abderrahim; Babaa, Fatima The widespread use of asynchronous motors is primarily attributed to their superiority over other motor types. They are notably cost-effective when it comes to maintenance. As such, it is essential to implement robust protective measures against major faults and to establish an effective functional monitoring system incorporating efficient preventive maintenance strategies. Predictive maintenance, in particular, can significantly enhance the cost-effectiveness and reliability of installations. The machine’s behavior evolves under varying fault conditions, making accurate fault identification critical and requiring a detailed and thorough analysis of the motor. In this context, the objective of our work is to diagnose faults that affect the motor throughout its operational lifespan. This is achieved using a model based on the detailed calculation of all the machine’s inductances. Among the most common faults is bearing failure, which is a key focus for devising an optimal maintenance strategy. Therefore, it is crucial to identify specific fault signatures that enable the prediction of fault progression. By analyzing various signals, we aim to extract reliable indicators and signatures that can be used not only for accurate fault prediction but also in industrial applications. To validate our analytical developments, experimental validation is indispensable. This step serves to confirm the accuracy of the simulated results for the various faults studied. To achieve this, test benches were employed to corroborate the findings derived from analytical calculations. Ultimately, the results obtained are highly indicative, particularly for faults such as power supply imbalances and bearing failures, and show strong alignment with findings reported in the literature.

2024-12-23T00:00:00Z Nebti, Oudjdane Oulamara, Hayet http://depot.umc.edu.dz/handle/123456789/14863 2026-10-19T11:04:30Z 2024-12-11T00:00:00Z

Petit déjeuner et obésité chez l’adulte Nebti, Oudjdane; Oulamara, Hayet Introduction. In recent years, many studies have demonstrated an association between skipping breakfast and weight status, but the results of different studies are inconsistent. Therefore, the main objective of the present study was to examine the relationship between breakfast and weight status in adults. Method. A cross-sectional survey was conducted on a sample of 1000 adults (60.2% female) with an average age of 33.9 ± 10.1 years. Data were collected using a questionnaire focusing on health status, breakfast related eating habits (consumption, frequency, conviviality and environment), and physical activity. Daily food intake was assessed using a 24-hour recall repeated three times. Anthropometric measurements included weight and height. Breakfast intake was evaluated using two methods: one based on frequency (more than three times per week) and the other on the energy intake of breakfast (15% of daily energy intake). Results and discussion. Our population comprises 55% overweight, including obese subjects, 21.7% of whom are obese. Nearly three-quarters of the subjects regularly have breakfast, with 83.8% having it more than three times per week, and over half (51.6%) have an energy intake at breakfast exceeding 300 kcal (15% of the total energy intake). Normalweight consumers have a longer sleep duration. Breakfast is a meal consumed at home by the majority of the population in less than 10 minutes on average. More than half of the individuals have it alone, without any activity. It usually consists of dairy products, mainly pasteurized semi-skimmed milk and coffee, accompanied by a cereal product (bread or cake), cakes or pastries. Over three-quarters of the subjects add sugar to coffee and milk consumed. Over three-quarters of the subjects add sugar to coffee and milk consumed. Breakfast constitutes a significant source of carbohydrates, lipids (especially cholesterol, saturated fatty acids, and monounsaturated fatty acids), and calcium. No significant difference was found in the prevalence of overweight and obesity between breakfast consumers and skippers. Although no correlation was found between the energy intake at breakfast and BMI, normal-weight consumers consume more calories at breakfast. Our study shows that regular breakfast consumption is not associated with body weight.

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