The Mn site in Mn-doped Ga-As nanowires: an EXAFS study

We present an EXAFS study of the Mn atomic environment in Mn-doped GaAs nanowires. Mn doping has been obtained either via the diffusion of the Mn used as seed for the nanowire growth or by providing Mn during the growth of Au-induced wires. As a general finding, we observe that Mn forms chemical bonds with As but is not incorporated in a substitutional site. In Mn-induced GaAs wires, Mn is mostly found bonded to As in a rather disordered environment and with a stretched bond length, reminiscent of that exhibited by MnAs phases. In Au-seeded nanowires, along with stretched Mn-As coordination we have found the presence of Mn in a Mn-Au intermetallic compound.Comment: This is an author-created, un-copyedited version of an article accepted for publication in Semiconductor Science and Technology. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The definitive publisher-authenticated version is available online at doi:10.1088/0268-1242/27/8/08500

Synthesis, characterization and photocatalytic performance of transition metal tungstates

Tungstates of divalent transition metals (MIIWO4, M = CoII, NiII, CuII, ZnII) were synthesized by reaction of transition metal nitrates with sodium tungstate. The precipitates were then calcined at 500 \ub0C. The materials were characterized by means of ICP-AES elemental analysis, UV\u2013Visible spectroscopy, X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and surface area analysis. The higher activity for the decolourization of Methylene Blue (MB) and Methyl Orange (MO) of ZnWO4 compared to that of the other investigated tungstates was correlated with its strong tendency of excitons self-trapping

Language disturbances in a group of participants suffering from Duchenne muscular dystrophy: a pilot study

Results from several studies suggest that the process of language acquisition may be altered in patients suffering from Duchenne Muscular Dystrophy (DMD). In this study, a group of eight male DMD participants (mean age: 16; SD 4.7) underwent an extensive neuropsychological and language assessment. Furthermore, they performed a discourse production task. Results evidenced mild mental retardation associated with a specific deficit in Verbal rather than Performance IQ. At the linguistic assessment, seven out of eight participants showed moderate to severe difficulties on oral language processing with particularly impaired morphosyntactic competence

Effects of thermal annealing on the structural properties of sputtered W-Si-N diffusion barriers

W-Si-N thin films were deposited via rf-magnetron sputtering from a W5Si3 target in Ar/N-2 reactive gas mixtures over a large range of compositions, obtained by varying the partial flow of nitrogen within the reaction chamber. The samples of each set were then thermally annealed in vacuum at different temperatures up to 980 degreesC. Film composition was determined by Rutherford backscattering spectrometry (RBS), surface film morphology by scanning electron microscopy (SEM), micro-structure by transmission electron microscopy (TEM), vibrational properties by FT-IR absorption and Raman scattering spectroscopy, and electrical resistivity by four-point probe measurements. Independently of the deposition conditions, all the as-deposited films have an amorphous structure, while their composition varies, showing an increase of Si/W ratio from 0.1 up to 0.55 when the nitrogen concentration in the films increases from 0 to 60 at%. Thermal treatments in vacuum induce an important loss of nitrogen in the nitrogen-rich samples, especially at temperatures higher than 600 degreesC. Samples with high nitrogen content preserve their amorphous structure even at the highest annealing temperature, despite the chemical bonding ordering observed by means of FTIR measurements. Raman spectroscopy of as-deposited films rich in nitrogen suggests the presence of an important amorphous silicon nitride component, but fails to detect any structural rearrangement either within the composite matrix of film or within silicon nitride component. Segregation of metallic tungsten was detected by TEM in the annealed sample with lowest nitrogen content (W58Si21N21). Finally, the resistivity of the films increases with the N content, while the loss of nitrogen accompanies the decrease of resistivity especially of samples with high nitrogen content

Focal cognitive impairment in mitochondrial encephalomyopathies: a neuropsychological and neuroimaging study.

Mitochondrial encephalomyopathies (ME) are a multisystemic group of diseases characterized by a wide range of biochemical and genetic mitochondrial defects with a variable mode of inheritance.We studied the neuropsychological profile, magnetic resonance imaging (MRI) and single photon emission computed tomography (SPECT) data in a group of ME patients in order to look for common or specific cognitive defects and a possible correlation with related brain areas. Three main cognitive areas were assessed: general intelligence, memory functions and visuo-perceptual skills. Our sample included 16 ME patients (nine males, seven females) aged 25\u201368 years (mean age 45.2, SD 13.0). No sign of mental deterioration was found in the group of elderly subjects. Despite subjects showing no global cognitive impairment they scored lower in nonverbal versus verbal tasks. Visuo-spatial skills and short-term memory were selectively impaired. There was no correlation between neuropsychological results and age, illness duration, age of onset, clinical phenotypes, genetic mitochondrial alterations and pharmacological therapy. The most frequent SPECT pattern observed was the hypoperfusion of temporal lobes, with a direct localization in the temporal cortex and with prevalent mesial involvement. The neuropsychological profile and SPECT imaging revealed similarities with focal defects