ABSTRACT
The rational synthesis of nanographenes and carbon nanoribbons directly on nonmetallic surfaces has been an elusive goal for a long time. We report that activation of the carbon (C)-fluorine (F) bond is a reliable and versatile tool enabling intramolecular aryl-aryl coupling directly on metal oxide surfaces. A challenging multistep transformation enabled by C-F bond activation led to a dominolike coupling that yielded tailored nanographenes directly on the rutile titania surface. Because of efficient regioselective zipping, we obtained the target nanographenes from flexible precursors. Fluorine positions in the precursor structure unambiguously dictated the running of the "zipping program," resulting in the rolling up of oligophenylene chains. The high efficiency of the hydrogen fluoride zipping makes our approach attractive for the rational synthesis of nanographenes and nanoribbons directly on insulating and semiconducting surfaces.
ABSTRACT
The self-assembling of 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) molecules deposited on an InSb(001) c(8 × 2) surface at sub-monolayer quantities has been investigated at low temperature (77 K) using scanning tunnelling microscopy. Sub-molecular resolution was obtained on PTCDA molecules. The results reveal that individual PTCDA molecules are arranged on the substrate in chains parallel to the [110] crystallographic direction, correlated with characteristic features of the low temperature InSb(001) c(8 × 2) surface electronic structure. A structural model for PTCDA molecules adsorbed on InSb is proposed.
ABSTRACT
We have used scanning tunnelling microscopy (STM) at 77 K to investigate 3,4,9,10-perylene-tetracarboxylic dianhydride (PTCDA) molecules adsorbed on an ultrathin (1-2 monolayer (ML)) film of KBr grown on a c(8 × 2)InSb(001) substrate. The molecules are stabilized both at the KBr steps and on the terraces. On the 1 ML film the PTCDA molecules appear predominantly as single entities, whereas on the 2 ML film formation of molecular clusters is preferred. Differences in the adsorption configurations indicate that the interaction between the molecules and the surface differs significantly for the cases of 1 and 2 ML films. We present images of the molecules obtained with sub-molecular resolution for both filled and empty state sampling modes. We argue that the highest occupied molecular orbital (the lowest unoccupied molecular orbital) is responsible for intramolecular contrast in filled (empty) state images of the molecules, even though they are deformed due to strong interaction with the substrate.
ABSTRACT
Two adult cases of centronuclear myopathy are described in a family from French Guyana. One of them, aged 23, has a slight weakness despite hypertrophic muscles. A typical picture of centronuclear myopathy was seen on muscle biopsy with atrophy of type I fibers and hypertrophy of II A fibers. His uncle, aged 53, had a progressive weakness of the lower limbs for the last 25 years, with also a pattern of centronuclear myopathy, but with more dystrophic features and atrophy of both type I and II A fibers. The mode of inheritance is dominant. These two cases are compared with the previously published reports. The pathogenesis of centronuclear myopathy is discussed.
Subject(s)
Muscular Diseases/genetics , Adult , Cell Nucleus/pathology , Fatigue/etiology , Humans , Leg , Male , Microscopy, Electron , Middle Aged , Muscular Diseases/pathology , Myofibrils/pathology , PedigreeABSTRACT
Paget's disease of the skull is the main cause of basilar artery syndromes in the adult. They may cause various neurological symptoms, including signs of ischemia of the spinal cord or medulla, or involvement of the cranial nerves and brain stem and, also, distant symptoms due to hydrocephalus, with various mental disorders including transient, recurrent, coma. The authors discuss 30 cases found in the world literature and 6 unreported personal cases, study the clinical symptoms of these cases of basilar artery compression due to Paget's disease, and the methods of neuro-radiological investigation, and emphasize the interest, in severe forms, of early surgical decompression before the stage of severe neurological complications. Regular supervision of patients with Pagets disease is thus essential to detect at an early stage, decompensation of basilar artery insufficiency in Paget's disease. In late forms, calcitonin may be indicated.
