Optimizing PMMA solutions to suppress contamination in the transfer of CVD graphene for batch production.

Mass production and commercial adoption of graphene-based devices are held back by a few crucial technical challenges related to quality control. In the case of graphene produced by chemical vapor deposition, the transfer process represents a delicate step that can compromise device performance and reliability, thus hindering industrial production. In this context, the impact of poly(methyl methacrylate) (PMMA), the most common support material for transferring graphene from the Cu substrate to any target surface, can be decisive in obtaining reproducible sample batches. Although effective in mechanically supporting graphene during the transfer, PMMA solutions needs to be efficiently designed, deposited, and post-treated to serve their purpose while minimizing potential contaminations. Here, we prepared and tested PMMA solutions with different average molecular weight (AMW) and weight concentration in anisole, to be deposited by spin coating. Optical microscopy and Raman spectroscopy showed that the amount of PMMA residues on transferred graphene is proportional to the AMW and concentration in the solvent. At the same time, the mechanical strength of the PMMA layer is proportional to the AMW. These tests served to design an optimized PMMA solution made of a mixture of 550,000 (550k) and 15,000 (15k) AMW PMMA in anisole at 3% concentration. In this design, PMMA-550k provided suitable mechanical strength against breakage during the transfer cycles, while PMMA-15k promoted depolymerization, which allowed for a complete removal of PMMA residues without the need for any post-treatment. An XPS analysis confirmed the cleanness of the optimized process. We validated the impact of the optimized PMMA solution on the mass fabrication of arrays of electrolyte-gated graphene field-effect transistors operating as biosensors. On average, the transistor channel resistance decreased from 1860 to 690 Ω when using the optimized PMMA. Even more importantly, the vast majority of these resistance values are distributed within a narrow range (only ca. 300 Ω wide), in evident contrast with the scattered values obtained in non-optimized devices (about 30% of which showed values above 1 MΩ). These results prove that the optimized PMMA solution unlock the production of reproducible electronic devices at the batch scale, which is the key to industrial production.

[Schizophrenia: What Non-Psychiatrist Physicians Need to Know]. / Esquizofrenia: O Que o Médico Não Psiquiatra Precisa de Saber.

Schizophrenia is a disabling and severe mental illness that affects all social classes and racial and ethnic groups, spreading across every part of the world. It's more frequent in males and it usually manifests itself in late adolescence or early adulthood and its early detection by all clinicians is important so that there is a proper referral to specialized psychiatric care. This article intends to update the knowledge regarding the diagnosis, treatment and prognosis of schizophrenia, with an emphasis on the warning signs for a timely referral to psychiatric evaluation. We conducted a literature search across through articles available in databases of scientific articles but also in scientific and technical books specialized in the field of schizophrenia. The clinical presentation of this illness is heterogeneous and complex, with a typical evolution based on several episodes of acute decompensation requiring hospitalization. The diagnosis of schizophrenia relies on some key symptoms, and the various international diagnostic criteria vary in relation to the temporal window with productive symptomatology required to establish a diagnosis. The prognosis is variable, not always deteriorating and is all the better when the treatment is started as early as possible. Treatment requires a multidisciplinary approach and is based primarily on antipsychotic drugs. This medication although very effective for the typical symptoms of this illness, entails some adverse effects with medical consequences that are important in the clinical practice of all doctors of other specialties.

A esquizofrenia é uma doença mental grave e incapacitante que afeta todas as classes sociais e raças, em todas as partes do mundo sendo mais frequente no sexo masculino. Manifesta-se habitualmente na parte final da adolescência ou início da vida adulta e é importante a sua deteção precoce por todos os clínicos para correto encaminhamento para consulta especializada de psiquiatria. Pretende-se com este artigo atualizar conhecimentos em relação ao diagnóstico, tratamento e prognóstico da esquizofrenia e enfatizando os sinais de alerta para uma referenciação atempada a consulta de psiquiatria. Foi efetuada uma pesquisa bibliográfica através de artigos disponíveis em bases de dados de artigos científicos e também em livros científicos e técnicos especializados na área da esquizofrenia. A apresentação clínica desta doença é heterogénea e complexa, com uma evolução típica normalmente pautada por vários episódios de descompensação aguda com necessidade de internamento. O diagnóstico de esquizofrenia assenta em alguns sintomas-chave, sendo que os vários critérios de diagnóstico internacionais variam entre eles relativamente à janela temporal com sintomatologia produtiva necessária para efetuar um diagnóstico. O prognóstico é muito variável, nem sempre cursa de forma deteriorante e é tanto melhor quando mais precoce for o início do tratamento. O tratamento exige uma abordagem multidisciplinar e assenta primariamente em fármacos antipsicóticos. Esta medicação apesar de muito eficaz para a sintomatologia típica da doença acarreta efeitos adversos cujas consequências médicas são importantes na prática clínica de todos os médicos de outras especialidades.

Formal Thought Disorders-Historical Roots.

In this article the authors intend to review in an intelligible and comprehensive way the historical roots of Formal Thought Disorders. Early descriptions of thought disorders date back to the XIX century with Esquirol, but it was in the first half of the XX century that several authors introduced the main features of the actual concept of Formal Thought Disorders. Emil Kraepelin described akataphasia (inability to find the appropriate expression for a thought) in patients with dementia praecox (a term that some years later was replaced by schizophrenia). Bleuler and Kretschmer also identified in schizophrenic patients a generalized "loosening of associations" and Carl Schneider described several Formal Thought Disorders such as derailment, fusion, omission, suspension and driveling. At the end of the XX century Nancy Andreasen studied the classical descriptions regarding Formal Thought Disorders, reclassified them and also introduced a scale to assess them. Although the specificity of these symptoms in schizophrenia and psychosis has been a source of controversy among the different authors, the importance given to their presence in these mental disorders is universal. We defend that it is crucial that these historical and conceptual elements are grasped in order to assess Formal Thought Disorders for clinical and research purposes.