Theoretical study of the effects of modifying the structures of organic dyes based on N,N-alkylamine on their efficiencies as DSSC sensitizers.

In this work, we carried out a theoretical study in which DFT and TD-DFT calculations of a series of six new organic dyes that incorporate N,N-alkylamine as an electron donor and a cyanoacrylic acid group as an electron acceptor and anchoring group were performed. In each dye, the donor and the acceptor were bridged by six different π-conjugated spacers consisting of an auxiliary donor group (3,4-ethylenedioxythiophene, EDOT) or an auxiliary acceptor group (benzothiadiazole, BTZ or diketopyrrolopyrrole, DPP) that was linked to either thiophene or phenyl. EHOMO, ELUMO, Egap, λmax, Eex, the open-circuit photovoltage (Voc), the light-harvesting efficiency (LHE), and the free injection energy (ΔGinject) were calculated for all of the dyes to compare their photovoltaic performance. The effects of the incorporation of an additional acceptor group (DPP or BTZ) or an additional donor group (EDOT) into the π-bridge on the geometry, electronic structure, and photovoltaic performance of each designed dye were explored. The study shows that modifying the dye skeleton can greatly improve the performance of the dye and increase its power conversion efficiency. It also reveals that all of the studied dyes are promising candidates for an effective DSSC sensitizer, especially those that include the acceptor group DPP in the π-bridge.

[Rotary C1-C2 dislocation: a case report]. / La luxation rotatoire C1-C2 : à propos d'une observation.

The atloid-axoid rotatory slipped disc is a rare pathology with still uncertain etiology. Many situations can be factors of this disease. We report a case in a child who was admitted to the hospital for a stiff neck that had been evolving for 1 month. The clinical examination found an irreducible angular deformity of the neck and multiple cervical adenopathies. The ORL examination was normal, the biological tests showed no disorders, and the X-ray examinations were also normal. Unexpected admission features were also disconcerting. The child suddenly presented a stiff neck on waking 2 days after a traditional circumcision at home, which might have been traumatizing. The mother also reported fever a few days before, attributed to rhinopharyngitis. Before his referral to the Rabat Children's Hospital, the child had received an anti-inflammatory treatment without any improvement. He had also been considered to have an opisthotonos on admission and was treated for suspected tetanus. Finally, the rotatory dislocation of C1-C2 was suggested, and a cervico-occipital junction scanner with three-dimensional reconstructions confirmed the diagnosis. The child was treated with cranial traction with good progression. This case opens the discussion of this rare disease, often unrecognized, which requires a multidisciplinary approach.