Search Results

The purpose of our investigation was to evaluate the acute toxicity of chromium tanning and liming-deliming waste waters before and after chemical treatment. The invertebrate Daphnia pulex was used for toxicity test. The toxicity due to these industrial waste waters was revealed by the equations of the regression lines. The results of the toxicity test showed that the waste waters from chromium tanning and from dehairing presented higher toxicity, with respective 24-h IC50 values of 0.15 and 3.36. This toxicity could be explained by higher levels of chromium, sulphides and organic matter in these waste waters.After processing by chemical precipitation, 24-h IC50 values increased from 0.15 to 26.6 and from 3.4 to 11.1 respectively for the chromium tanning and the de-hairing waste waters. Consequently, these processed effluents can be classified as low toxic wastes. This diminution of the toxicity is linked to a reduction of suspended matter (95 %), COD (55 %), Cr (90 %) and sulphides (50 %). Hence, this treatment presents at least two advantages. The first is environmental, as just mentioned; the second is economic, since chromium can be recycled for reuse in leather tanning. The results suggest that the recovered chromium is similar to commercial tanning chromium. In fact, a techno-economical analysis showed that proposed treatment project can be economically beneficial (3112,50 $ per 1000 tons per year).

Keywords: Tannerie, chrome, toxicité, traitement chimique, réutilisation, analyse financière, test Daphnie, Tannery, chromium, toxicity, chemical treatment, reuse, financial analysis, test daphnia

The Sahela reservoir, located in Taounate at 90 km from Fès, lying at an altitude of 325 m, was built to provide drinking water for the population of Taounate and to contribute to irrigate neighbouring farming perimeters.In order to assess the impact of metazoan zooplankton on phytoplankton and protozoan ciliates in the Sahela reservoir under semi-arid climate, we conducted experiments during the period from July to December 1999 at the deepest point in the lake (15 m).Sampling and measurements were carried out in diffusion chambers submerged in situ over a period of 7 h without (control chambers) and with (experimental chambers) zooplankton. During these experiments, counts were conducted on phytoplankton and ciliates to determine the abundance and the mortality of these organisms due to zooplankton in each diffusion chambers at t=0 and t=7 h incubation. The metazooplankton were counted and dry weight of each taxa was calculated.In summer the highest zooplankton biomass (150 µg·L-1) mainly composed of cyclopoid Tropocyclops prasinus, caused mortality of the small-sized ciliates, such as Halteria grandinella (0.10 h-1). In Autumn, the zooplankton biomass (75 µg·l-1), dominated by Daphnia longispina, induced a higher mortality for phytoplankton (0.10 h-1) than for ciliates (0.05 h-1). In Winter, the zooplankton biomass (100 µg·L-1), also represented by Daphnia longispina, had a low impact on ciliate mortality (< 0.02 h-1).The study showed that a heavy predation by the metazoan zooplankton was exerted on small-sized phytoplankton and ciliates and clearly demonstrated the relationships between protozoans and metazoan zooplankton to transfering the matter and energy in aquatic food webs.

Keywords: Réservoir, zooplancton, phytoplancton, ciliés, Reservoir, zooplankton, phytoplankton, ciliates

Any human activity generates noise. It is considered as a risk factor for people's health. The present review of literature has assessed the impact of noise on mental health; it is summarized into four points: objective, methods, results and conclusion. Objective: The main objective of this study is to expose the actual knowledge state of noise effects on mental health after overview and critical analysis of literature to identify the acquired and shortcomings, to reflect on research direction in terms of noise pollution in the future. Methods: The literature review was conducted based on: research of keys words in articles published, research of the number of quotations of articles in Journal Citation Reports (JCR), published in web of science, research of impact factor of journals. One hundred articles were selected, after analyzing contents, items were classified into: fundamental studies (25%), experimental studies (50%), and epidemiological studies (25%). Results: The fundamental studies have verified the hypothesis according to which noise generates stress. Researchers have dosed hormones of stress in plasma, urine and saliva in individuals exposed to noise of different decibels. The results found were unanimous: The rates of stress hormones found, were significantly high in three liquids. This means that noise causes stress. For experimental studies, researchers have experienced the role of noise on memory, attention and performance. Human subjects were exposed to different decibels to assess level of disruption to their memory, attention, and performance. The results revealed that noise disturbs memory, distracts attention and decreases performance. Experimental studies are the most abundant and constitute 50% of the current literature review.The epidemiological studies have evaluated the intellectual performance of students in schools located in noisy environments and residents in areas surrounding airports, railways and highways. Results have revealed that students in schools located in noisy environments have presented cognitive impairment. Conclusion: This review of literature on noise effects on mental health lead to the following conclusion. It seems to exist a consensus in fundamental and experimental studies on the detrimental effect of noise but results from epidemiological are not convincing and require further studies.

Keywords: stress, bruit, mémoire, attention, performance, déficits cognitifs, memory, attention, performance, cognition impairment, stress and noise

School is not part of the domain of social work. The same questions, however, traverse the school space, a social space par excellence, and the institutions that come under this domain. Hence the question of considering the religious, which resurfaced twenty years ago with the first polemics on the so-called “Islamic” headscarf being worn at school, challenging a secularity that until then seemed unshakeable.In 2002, the “Debray Report” put forward the need to reinforce the study of the religious as an aspect of culture. “The idea is not to put ‘God back into the classroom', but to understand that religious traditions and the future of human cultures are carried on the same boat” (Debray, 2002 : 5 – our translation) and to combat the ignorance that gives rise to irrationality and fanaticism.The school rightly relegates individuals' personal convictions to the private sphere. In the name of this separation of private and public spheres, it overlooks the existence of these convictions held by its students, abandoning the latter to their spiritual quest and search for identity and refusing to see the consequences of this conception of poorly-understood secularity.In fact, French secularity is not incompatible with considering the religious in school. On the contrary, it provides the ideal framework for understanding that religion is only a particular variation of a shared phenomenon that traverses – and structures – all human societies, for learning to relativize and not demonize the other's religion or non-religion, and for gaining access, beyond worship per se, to texts and representations in the figurative, symbolic sense.Today, however, teachers are not sufficiently trained and all too often approach religious facts in the form of a catalogue, without establishing the links between them that are indispensable for any students, whatever their cultural, family or personal references, to understand not only the history of humanity, but also that of our contemporary societies.

Lymantria dispar (Lepidoptera, Lymantriidae) is one of the most destructive insect pests in Algerian cork oak forests. The identification of areas infested between 1968 and 2013 by this insect indicates three main peaks of culminations in 1977, 1987 and 1996 during which 13,445, 28,157 and 20,793 ha of forests were defoliated, respectively. Eastern coastal forests seem to be the most vulnerable. For the first time in Algeria, we conducted a test on first larval instars with two commercial products based on Bacillus thuringiensis Berliner var. kurstaki (Btk) serotype 3a-3b at a concentration of 16,000 International Units per milligram (IU/mg) in three infested areas in order to determine the optimal conditions for using bio-insecticides in cork oak forests. Surveys conducted 20 d after helicopter spraying showed that mortality from the first to the third instars reached at least 90% in the areas treated. Rearing caterpillars and pupae that survived the treatment revealed a delayed mortality of 16.0 to 38.8% in the treated areas. Pupal mortality was mainly due to Hymenoptera, Diptera and pathogenic microorganisms.

Keywords: Bacillus thuringiensis, défoliation, ennemis naturels, infestation, Lymantria dispar, Quercus suber, Bacillus thuringiensis, defoliation, infestation, Lymantria dispar, natural enemies, Quercus suber

The historiography gives to France a central role, often even disproportionate to the growth of Québec's international relations in the years 1960. The objective of this study is not to question the importance of the relation France-Quebec, but simply to bring the look elsewhere, especially to the countries of the third world in the context of the first attempts to institutionalize the Francophonie. Our focus is to explore the relationship of Quebec politicians in these countries to discover the ins and outs of the conceptions of African Other. If diplomatic exchanges between Quebec, Canada and French-speaking Africa were detailed, the racial issue remains invisible.

In the background of the world of documentation in Africa, the author stresses the need for objectives, planification, autonomous recruiting, personnel training, and services of quality. He suggests some guidelines: bibliographic control, interlibrary cooperation, training of personnel, and the use of computers.

This article talks about a new cultural and intellectual phenomenon witnessed lately in the Arab world. We call it here “new humanist Arab movement” in view of its resemblance with what happened in Europe during the Renaissance and what happened in the Islamic world during the Golden Age. We believe this movement can be divided into 3 branches: Secular, reformist and anti-religious.

Keywords: progressisme arabe, humanisme arabe contemporain, révolution intellectuelle dans le monde arabe, irréligion arabe, réforme de la religion dans le monde arabe, Arab progressive movement, contemporary Arab progressives, cultural revolution in the Arab world, secularization in the Arab world, religious reform in the Arab world