Nanoscale tunable reduction of graphene oxide for graphene electronics

International audienceGraphene is now recognized as the most likely carbon-based successor material for CMOS electronics. Recently, interest in graphene oxide (GO) has risen for producing large-scale flexible conductors and for its potential to open an electronic gap in graphene structures. We report on a means to tune the topographical and electrical properties of graphene-based materials with nanoscopic resolution by local thermal reduction of GO with a nano-size tip. The reduced GO nanostructures show an increase in conductivity up to four orders of magnitude as compared to pristine GO. No sign of tip wear or sample tearing was observed. Variably conductive nanoribbons with dimensions down to 12 nm have been produced in oxidized epitaxial graphene films in a single step that is clean, rapid and reliable

Supramolecular interactions in clusters of polar and polarizable molecules

We present a model for molecular materials made up of polar and polarizable molecular units. A simple two state model is adopted for each molecular site and only classical intermolecular interactions are accounted for, neglecting any intermolecular overlap. The complex and interesting physics driven by interactions among polar and polarizable molecules becomes fairly transparent in the adopted model. Collective effects are recognized in the large variation of the molecular polarity with supramolecular interactions, and cooperative behavior shows up with the appearance, in attractive lattices, of discontinuous charge crossovers. The mean-field approximation proves fairly accurate in the description of the gs properties of MM, including static linear and non-linear optical susceptibilities, apart from the region in the close proximity of the discontinuous charge crossover. Sizeable deviations from the excitonic description are recognized both in the excitation spectrum and in linear and non-linear optical responses. New and interesting phenomena are recognized near the discontinuous charge crossover for non-centrosymmetric clusters, where the primary photoexcitation event corresponds to a multielectron transfer.Comment: 14 pages, including 11 figure

Efficient light emission from inorganic and organic semiconductor hybrid structures by energy level tuning

The fundamental limits of inorganic semiconductors for light emitting applications, such as holographic displays, biomedical imaging and ultrafast data processing and communication, might be overcome by hybridization with their organic counterparts, which feature enhanced frequency response and colour range. Innovative hybrid inorganic/organic structures exploit efficient electrical injection and high excitation density of inorganic semiconductors and subsequent energy transfer to the organic semiconductor, provided that the radiative emission yield is high. An inherent obstacle to that end is the unfavourable energy level offset at hybrid inorganic/organic structures, which rather facilitates charge transfer that quenches light emission. Here, we introduce a technologically relevant method to optimize the hybrid structure's energy levels, here comprising ZnO and a tailored ladder-type oligophenylene. The ZnO work function is substantially lowered with an organometallic donor monolayer, aligning the frontier levels of the inorganic and organic semiconductors. This increases the hybrid structure's radiative emission yield sevenfold, validating the relevance of our approach

Topological doping and the stability of stripe phases

We analyze the properties of a general Ginzburg-Landau free energy with competing order parameters, long-range interactions, and global constraints (e.g., a fixed value of a total ``charge'') to address the physics of stripe phases in underdoped high-Tc and related materials. For a local free energy limited to quadratic terms of the gradient expansion, only uniform or phase-separated configurations are thermodynamically stable. ``Stripe'' or other non-uniform phases can be stabilized by long-range forces, but can only have non-topological (in-phase) domain walls where the components of the antiferromagnetic order parameter never change sign, and the periods of charge and spin density waves coincide. The antiphase domain walls observed experimentally require physics on an intermediate lengthscale, and they are absent from a model that involves only long-distance physics. Dense stripe phases can be stable even in the absence of long-range forces, but domain walls always attract at large distances, i.e., there is a ubiquitous tendency to phase separation at small doping. The implications for the phase diagram of underdoped cuprates are discussed.Comment: 18 two-column pages, 2 figures, revtex+eps

Report on ISCTM consensus meeting on clinical assessment of response to treatment of cognitive impairment in schizophrenia

Funding for this manuscript was provided by the International Society for CNS Clinical Trials and Methodology.Dr Keefe currently or in the past 3 years has received investigator-initiated research funding support from the Department of Veteran's Affair, Feinstein Institute for Medical Research, GlaxoSmithKline, National Institute of Mental Health, Novartis, Psychogenics, Research Foundation for Mental Hygiene, Inc., and the Singapore National Medical Research Council. He currently or in the past 3 years has received honoraria, served as a consultant, or advisory board member for Abbvie, Akebia, Amgen, Asubio, AviNeuro/ChemRar, BiolineRx, Biogen Idec, Biomarin, Boehringer-Ingelheim, Eli Lilly, EnVivo/FORUM, GW Pharmaceuticals, Janssen, Lundbeck, Merck, Minerva Neurosciences, Inc., Mitsubishi, Novartis, NY State Office of Mental Health, Otsuka, Pfizer, Reviva, Roche, Sanofi/Aventis, Shire, Sunovion, Takeda, Targacept, and the University of Texas South West Medical Center. Dr Keefe receives royalties from the BACS testing battery, the MATRICS battery (BACS Symbol Coding), and the Virtual Reality Functional Capacity Assessment Tool. He is also a shareholder in NeuroCog Trials, Inc. and Sengenix. Dr Haig is a full-time employee of Abbvie. Dr Marder has received consulting fees from Abbvie, Genentech, Roche, Lundbeck, Pfizer, Otsuka, Takeda, and Boeringer Ingelheim. He has received research support from Amgen, Sunovion, and Synchroneuron. Dr Harvey has received consulting fees from Abbvie, Boehringer Ingelheim, Forest Labs, Forum Pharma, Genentech, Otsuka America, Roche Pharma, Sunovion Pharma, and Takeda Pharma during the past year. He also received contract research support from Genentech. Dr Dunayevich for the past 3 years has been a full-time employee and stockholder of Amgen. Dr Medalia in the past 3 years has received research funding support from Sunovion. Dr Medalia has also currently or in the past 3 years received honoraria or served as consultant for Dainippon Sumitomo Pharma Co., Ltd., Otsuka, and Takeda Pharmaceuticals U.S.A., Inc. Dr Davidson has received research grant support and/or travel support and/or speaker fees and/or consultancy fees from Lundbeck, Eli Lilly, Servier, Abbott, Minerva and holds stocks in CTR and BiolineRx. Dr Lombardo is a full-time employee of FORUM Pharmaceuticals. Dr Bowie reports receiving grant support from Pfizer. He has also been a consultant for Lundbeck, Otsuka, Abbvie, and Takeda. Dr Buchanan reports: Advisory Board: Abbvie, Amgen, EnVivo, Roche; Consultant: Abbvie, Amgen, Bristol Myers Squibb, EnVivo, Omeros; DSMB member: Pfizer. Dr Bugarski -Kirola is a full-time employee of Hoffmann-La Roche Ltd. Dr Carpenter in the past 2 years has been a consultant to Roche/Genetech. Dr Dago in the last 3 years has received honoraria from Lundbeck, Forest Pharmaceuticals, Otsuka, Pam Labs, and Astra Zeneca for lectures given in promotion of their psychotropic medications. Dr Durand in the past year has been a consultant and received honoraria from Teva Pharmaceuticals. Dr Gold receives royalty payments from the BACS. He also has served as a consultant for Amgen, Hoffman LaRoche, and Lundbeck. Dr Hooker has served as a consultant and is currently a Co-Investigator on an NIH SBIR grant with PositScience Corporation. Dr Loebel is an employee of Sunovion Pharmaceuticals. Dr McGurk reports receiving consulting fees from Abbvie and EnVivo Pharmaceuticals. Dr Pinkham in the past year has received consulting fees from Otsuka America Pharmaceutical, Inc.The following authors have declared that there are no conflicts of interest in relation to the subject of this study: Drs Csernansky, Frese, Goff, Kopelowic, Opler, and Stern. (International Society for CNS Clinical Trials and Methodology; Department of Veteran's Affair; Feinstein Institute for Medical Research; GlaxoSmithKline; National Institute of Mental Health; Novartis; Psychogenics; Research Foundation for Mental Hygiene, Inc.; Singapore National Medical Research Council; Abbvie; Genentech; Roche; Lundbeck; Pfizer; Otsuka; Takeda; Boeringer Ingelheim; Amgen; Sunovion; Synchroneuron; Boehringer Ingelheim; Forest Labs; Forum Pharma; Otsuka America; Roche Pharma; Sunovion Pharma; Takeda Pharma; Eli Lilly; Servier; Abbott; Minerva; BACS; EnVivo Pharmaceuticals; Otsuka America Pharmaceutical, Inc.)Published versio

Contributions of common genetic variants to risk of schizophrenia among individuals of African and Latino ancestry

Schizophrenia is a common, chronic and debilitating neuropsychiatric syndrome affecting tens of millions of individuals worldwide. While rare genetic variants play a role in the etiology of schizophrenia, most of the currently explained liability is within common variation, suggesting that variation predating the human diaspora out of Africa harbors a large fraction of the common variant attributable heritability. However, common variant association studies in schizophrenia have concentrated mainly on cohorts of European descent. We describe genome-wide association studies of 6152 cases and 3918 controls of admixed African ancestry, and of 1234 cases and 3090 controls of Latino ancestry, representing the largest such study in these populations to date. Combining results from the samples with African ancestry with summary statistics from the Psychiatric Genomics Consortium (PGC) study of schizophrenia yielded seven newly genome-wide significant loci, and we identified an additional eight loci by incorporating the results from samples with Latino ancestry. Leveraging population differences in patterns of linkage disequilibrium, we achieve improved fine-mapping resolution at 22 previously reported and 4 newly significant loci. Polygenic risk score profiling revealed improved prediction based on trans-ancestry meta-analysis results for admixed African (Nagelkerke’s R2 = 0.032; liability R2 = 0.017; P < 10−52), Latino (Nagelkerke’s R2 = 0.089; liability R2 = 0.021; P < 10−58), and European individuals (Nagelkerke’s R2 = 0.089; liability R2 = 0.037; P < 10−113), further highlighting the advantages of incorporating data from diverse human populations