Nitrogen-Doped Graphene Materials with High Electrical Conductivity Produced by Electrochemical Exfoliation of Graphite Foil.

Nitrogen-doped graphene-based materials are of utmost importance in sensing and energy conversion devices due to their unique physicochemical properties. However, the presence of defects such as pyrrolic nitrogen and oxygenated functional groups reduces their electrical conductivity. Herein, a two-step approach based on the electrochemical exfoliation of graphite foils in aqueous mixed electrolytes followed by thermal reduction at 900 °C is used to prepare high-quality few layers of N-doped graphene-based materials. The exfoliations were conducted in 0.1 M (NH4)2SO4 or H2SO4 and HNO3 (5 mM or 0.1 M) electrolytes mixtures and the HNO3 vol% varied. Chemical analysis demonstrated that the as-prepared graphene oxides contain nitro and amine groups. Thermal reduction is needed for substitutional N-doping. Nitrogen and oxygen surface concentrations vary between 0.23-0.96% and 3-8%, respectively. Exfoliation in (NH4)2SO4 and/or 5 mM HNO3 favors the formation of pyridinic-N (10-40% of the total N), whereas 1 M HNO3 favors the formation of graphitic-N (≈60%). The electrical conductivity ranges between 166-2705 Scm-1. Raman spectroscopy revealed a low density of defects (ID/IG ratio between 0.1 and 0.7) and that most samples are composed of mono-to-bilayer graphene-based materials (IG/I2D integrated intensities ratio). Structural and compositional stability of selected samples after storage in air for three months is demonstrated. These results confirm the high quality of the synthesized undoped and N-doped graphene-type materials.

Patient taking chemotherapy for a small cell lung cancer: not every cerebral nodule is a metastasis: the tree that hides the forest.

We report the case of a 53- year-old man in whom the diagnosis of small cell lung cancer (SCLC) was made by the biopsy of a mass of the right trapezius muscle. A tumor was revealed on flexible bronchoscopy which pathological study showed tuberculosis (TB). Chest computed tomography (CT) scan revealed findings related to the SCLC associated to micronodules and nodules compatible with pulmonary TB. Cerebral CT scan revealed a nodule of 4.5 mm in diameter presenting enhancement after contrast material injection thought to be a metastasis. The patient was administered antitubercular treatment. Fiveteen days later, the patient started chemoptherapy with etoposid and carboplatin. A control cerebral CT scan realized after the end of the chemotherapy (2 months and a half of antitubercular treatment) revealed numerous cortical and subcortical infracentimetric nodules with contrast enhancement with a tentorial and subtentorial location considered to be in relation with cerebral miliary TB. The nodule discovered on the first cerebral scan was therefore a posteriori considered to have been of tubercular origin. The PS of the patient rapidly worsened. He presented mental confusion and died in some days.

[Laser contribution in angle closure glaucoma]. / Apport du laser dans les glaucomes aigus par fermeture de l'angle.

BACKGROUND: A better understanding of angle-closure glaucoma mechanisms is necessary to indicate the appropriate treatment. AIM: the aim of our study is to discuss the laser indication in various type of angle-closure glaucoma. METHODS: The study investigate 25 eyes of 22 patients who had an angle-closure glaucoma. The mechanisms are an anterior chamber angle blockage in 19 eyes, a plateau iris structure in 4 eyes and a nanophthalmos in 2 eyes. RESULTS: Laser peripheral iridotomy is the most used technic; it was practised in 19 eyes. Argon laser iridoplasty was practised in 4 cases of plateau iris structure and in 2 patients who had a residual angle closure with a functional iridotomy. CONCLUSION: Laser is an effective alternative in the treatment of angle-closure glaucoma and can alleviate the need for high-risk filtering surgery.