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1

Oxfordian brachiopods from the Saïda and Frenda mountains (Tlemcenian Domain, north-western Algeria)

Halamski A. T., Cherif A.

Annales Societatis Geologorum Poloniae

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2017

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Vol. 87, No. 2

141--156

EN

Five brachiopod species are reported from two middle to upper Oxfordian (Late Jurassic) outcrops, situated in the Saïda and Frenda mountains (Tlemcenian Domain, north-western Algeria) and belonging to the heterochronous (Callovian to Oxfordian, locally to the Kimmeridgian) Argiles de Saïda Formation (Saïda Clay Formation). The upper Oxfordian (probably Dichotomoceras bifurcatus Zone) outcrop A yielded Dictyothyris kurri and Loboidothyridoidea indet. The middle Oxfordian (Liosphinctes plicatilis Zone, Cardioceras vertebrale Subzone) outcrop B yielded Monticlarella rollieri, Karadagithyris boullierae sp. n., and Zittelina sp.; this is the first report of the last-mentioned genus from Africa. Karadagithyris boullierae sp. n. is a link between previously known Bajocian to Bathonian (Callovian?) Karadagithyris s.s. and Tithonian to Lower Cretaceous species, formerly segregated as Svaljavithyris; the latter is considered herein as synonym of Karadagithyris. It is characterised by a plano-uniplicate anterior commissure and a suberect beak. The adult loop of Zittelina is confirmed as bilacunar (kingeniform) and not diploform (campagiform). The bulk of the assemblages comprises small and either smooth or finely ornamented species and thus represents a low-energy environment. The lack of modern revisions of the reported species in their type areas is the reason why only Dictyothyris kurri may be used as an index species for the middle to late Oxfordian.

2

Up-conversion fluorescence dynamics in Er3+/Yb3+ co-doped tellurite glasses

Cherif A., Kanoun A., Maaref H.

Optica Applicata

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2011

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Vol. 41, nr 1

235--245

EN

The infrared to visible conversion in zinc tellurite glasses (TZG), activated by Er3+ ions and sensitized by Yb3+ ions, has been investigated under 980 nm pulsed laser excitation. The up-conversion mechanism was studied by means of time-resolved luminescence spectroscopy. A model for the dynamics of frequency up-conversion in Er3+/Yb3+ co-doped TZG based on the rate equations was proposed. The dynamics of the up-converted emissions were studied to evaluate energy rates between Er3+ and the Yb3+ ions, and the rate excited state absorption (ESA) in Er3+ ions.

3

Red up-conversion dynamics in Er3+-doped TeO2-ZnO glasses

Cherif A., Kanoun A., Jaba N.

Optica Applicata

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2010

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Vol. 40, nr 1

109--118

EN

Red fluorescence has been obtained under 980 nm excitation in Er3+-doped TeO2-ZnO glasses. The dynamics of the red up-conversion is well explained with the proposed model. The energy transfer processes are predominant.