4 research outputs found
Optimisation des propriétés physico-chimiques et photocatalytiques des couches minces à base d’oxyde
No full textDans ce travail, des films minces de ZnO non dopé et dopé au Ba ont été déposés sur des substrats en verre par une méthode simple et économique d'adsorption et de réaction successive des couches ioniques (SILAR). Ces films ont été étudiés à l'aide de diverses techniques. Afin d'optimiser la
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qualité de nos films, nous avons étudié l'influence des concentrations de dopant, du nombre de cycles de dépôt et de la température de recuit sur les propriétés structurales, morphologiques, optiques et photocatalytiques des films. Tous les échantillons ont montré une nature polycristalline avec une phase hexagonale de type wurtzite. Les spectres de diffraction des rayons X ont montré que la cristallisation des films de ZnO dopés à 5 % en masse de Ba était meilleure que celle des échantillons non dopés, avec une orientation préférentielle le long du plan (100). Les images SEM ont révélé que les films étaient bien adhérents et uniformes. Les spectres UV-Vis ont montré que la transmittance des films augmentait avec l'augmentation de la concentration en Ba, démontrant ainsi une meilleure transparence optique. Les films de ZnO dopés à 5 % en Ba ont présenté la meilleure efficacité photocatalytique, atteignant une dégradation de 95,78 % de MB sous irradiation solaire pendant 5 heures. Cet échantillon a montré une stabilité et une réutilisabilité exceptionnelles, conservant ses performances sur cinq cycles.
D'autre part, les films de ZnO dopés à 5 % en Ba, déposés avec différents nombres de cycles, ont montré qu'une augmentation du nombre de cycles de dépôt conduisait à une meilleure cristallinité aux cycles plus élevés. En conséquence, l'efficacité photocatalytique a augmenté pour atteindre 93,51 % après 15 cycles.
De plus, les résultats ont montré que le processus de recuit à 450°C améliore la cristallinité, les propriétés optiques et l'efficacité photocatalytique des films de ZnO dopés au Ba, atteignant une dégradation de 96,17 % de MB, qui a progressivement diminué à 94,89 % après cinq cycles successifs
The class of c-almost periodic functions defined on vertical strips in the complex plane
No full textIn this paper, we develop the notion of c-almost periodicity for functions defined on vertical strips in the complex plane. As a generalization of Bohr’s concept of almost periodicity, we study the main properties of this class of functions which was recently introduced for the case of one real variable. In fact, we extend some important results of this theory which were already demonstrated for some particular cases. In particular, given a non-null complex number c, we prove that the family of vertical translates of a prefixed c-almost periodic function defined in a vertical strip U is relatively compact on any vertical substrip of U, which leads to proving that every c-almost periodic function is also almost periodic and, in fact, cm-almost periodic for each integer number m.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. The first author was supported by 076 Bis/PG/Espagne/2020-2021 (Ministère de l’Enseignement Supérieur et de la Recherche Scientifique). The second and corresponding author was supported by PGC2018-097960-B-C22 (MCIU/AEI/ERDF, UE)
The Study of Dielectric Properties of Some Ionic Liquids Based on Imidazolium by Dielectric Spectroscopy and Data Mining
No full textAbstractIonic liquids (ILs) are liquid salts of differentiating to all molten salts with temperature below 100° C (arbitrarily set with reference to the boiling point of water), but a large number of them are liquids at room temperature. The properties of ionic liquids such as their wide field of electro activity, their high conductivity, and high thermal stability have made them new prime candidates in searching for a new energy systems (photovoltaic cell, battery, solar concentrator ...). The present work objective is to study the physicochemical properties of some ionic liquids based on imidazolium ([BMIM]+ [BF4]-, [BMIM]+[PF6]-, [HMIM]+ [Br] -,[BMIM]+ [Br]−) and more particularly the dielectric properties. We performed measurements by dielectric spectroscopy to see the influence of the size of the anion and the length of the alkyl chain of the cation on the conductivity of ionic liquids at different temperatures. We made also theoretical study by using data mining techniques such as the analytical method principal components (PCA), that help us to study the relationships between variables (σ RT (S / m), Tg (K) lnσ∞ (S / m), B, T0 (K), m) and their relation with ionic liquids structure
Military Regimes, Political Power and Human Rights Violations in Postcolonial Algeria
No full textFollowing Algeria’s bloody war of independence, a new, revolutionary military establishment gradually formed out of several largely independent revolutionary units, stationed mostly on Algeria’s borders. It soon expanded with the addition of revolutionary fighters from within Algeria, and from French-trained forces, many of whom had fought against the revolutionary forces during the Revolution, and had deserted late in the war from the French military to join the new Algerian military. A particularly powerful group of officers emerged from the latter group, the “French Officers,” who apparently engaged in a long-term and ultimately successful bid for national political power.
This thesis, which is concerned with the politics behind the massive human rights violations in Algeria, particularly the periods immediately after Independence, and between 1991 and 2002, the “Algerian Civil War,” seeks to explore a central question: why did the Algerian military turn against its own people? While not denying the role of other groups (e.g., religious groups, ethnic groups) in the violence, the central focus of this thesis is on the distinctive and effective structure and role of the military, which was apparently the dominant political power in Algeria after Independence, and particularly on the role of the French Officers, who appear to have manipulated the presidency through coups d’état and assassinations, in their struggle to achieve political hegemony in Algeria by the 1990s. Central to this was the role played after Independence by Houari Boumédiène in establishing political and military organisations that were particularly susceptible to the growing influence of the French Officers.
Central topical foci of the thesis include examinations of the possible effects (on the central question, listed above) of: professionalization of the military; civil-military relations; historical influences; ethnic and religious influences; political parties and party formation; corruption and economic opportunism; international relations and continuing French influence; and the unique role of the French Officers in the national politics of Algeria.
Methodologies used in this study included the analysis of elite (non-random) interviews, based upon a questionnaire approved by the Faculty of Arts and Social Sciences Research Ethics Committee, which the author conducted in Europe and via “Skype” with nearly two dozen prominent Algerian expatriates, for the most part in exile, including former civilian leaders and military officers. Historical analysis was also a central part of the methodology, as well as discourse analysis applied to significant memoirs and newspaper accounts.
The thesis concludes that the immediate self-interests of the French Officers had a determinate effect on politics in Algeria, and particularly on the way in which the military turned against its own people after 1991. The continuing support that the French Officers apparently received from France, while not unexpected, is surprising in its extent and continuity, particularly after acts of terrorism thought to be linked to the Algerian government occurred in France. An unexpected finding of this research is the significance of corruption and economic opportunism in the Algerian military regime’s long-term strategy
