New insights in the electronic transport in reduced graphene oxide using Scanning Electrochemical Microscopy

International audienceGraphene and graphene analogues such as GO or reduced-GO (r-GO) are attracting increasing attention from the scientific community. These materials have outstanding properties, so that many potential applications in the fields of electronics, sensors, catalysis and energy storage are being considered. GO combines several advantages such as availability in large quantity, low cost and easy processability. However, contrary to graphene, GO is electronically insulating and has to be reduced into a conductive material, r-GO. In a recent work we introduced a new localized functionalization method of GO deposited on a silicon oxide surface based on its reduction at the local scale thanks to scanning electrochemical microscopy (SECM): the reducer is generated at the microelectrode, that is moved close to the substrate. The recovery of electronic conductivity upon reduction enables the selective electrochemical functionalization of patterns. In the present work, we introduce a new method to evaluate at a local scale the conductivity of r-GO layers with SECM. In addition we show how images of individual and interconnected flakes directly reveal the signature of the contact resistance between flakes in a non-contact and substrate-independent way. Quantitative evaluation of the parameters is achieved with the support of numerical simulations to interpret the experimental results. Overall, these works illustrates the high potential and versatility of SECM to investigate and functionalize 2D materials

New insights in the electronic transport in reduced graphene oxide using Scanning Electrochemical Microscopy

International audienceGraphene and graphene analogues such as GO or reduced-GO (r-GO) are attracting increasing attention from the scientific community. These materials have outstanding properties, so that many potential applications in the fields of electronics, sensors, catalysis and energy storage are being considered. GO combines several advantages such as availability in large quantity, low cost and easy processability. However, contrary to graphene, GO is electronically insulating and has to be reduced into a conductive material, r-GO. In a recent work we introduced a new localized functionalization method of GO deposited on a silicon oxide surface based on its reduction at the local scale thanks to scanning electrochemical microscopy (SECM): the reducer is generated at the microelectrode, that is moved close to the substrate. The recovery of electronic conductivity upon reduction enables the selective electrochemical functionalization of patterns. In the present work, we introduce a new method to evaluate at a local scale the conductivity of r-GO layers with SECM. In addition we show how images of individual and interconnected flakes directly reveal the signature of the contact resistance between flakes in a non-contact and substrate-independent way. Quantitative evaluation of the parameters is achieved with the support of numerical simulations to interpret the experimental results. Overall, these works illustrates the high potential and versatility of SECM to investigate and functionalize 2D materials

Consumo alcoólico entre universitários(as) da área da saúde da Universidade Federal do Rio Grande/RS: subsídios para enfermagem Consumo alcohólico entre universitarios(as) del área de la salud de la Universidade Federal do Rio Grande/RS: subsidios para enfermería Alcohol consumption among university students in the health area of Federal University of Rio Grande/RS: subsidy to the nursing

Objetivou-se conhecer os fatores associados e as consequências do uso de bebidas alcoólicas entre universitários da área de saúde da Universidade Federal do Rio Grande/RS. A amostra foi composta por 351 estudantes do primeiro e do penúltimo anos de cada curso. Aplicou-se um questionário sociodemográfico e o AUDIT na coleta de dados. Na análise utilizaram-se testes estatísticos. Verificou-se que 202 (57,5%) estudantes bebiam habitualmente; desses, 196 (97,0%) tinham familiares usuários(as) de álcool. Segundo o AUDIT os estudantes foram classificados em baixo risco, 147 (41,8%), e de uso problemático, 49 (14,0%). Como consequências detectaram-se apagões, coma alcoólico e acidentes automobilísticos. Constatou-se que 171(48,7%) estudantes não utilizaram preservativo nas últimas relações sexuais e 37 (10,5%) tiveram três a dez parceiros (as) nos últimos 12 meses. Evidenciou-se a necessidade de implementação de estratégias de cunho preventivo no âmbito universitário, para detectar precocemente o potencial para uso abusivo, bem como oportunidade de tratamento aos(às) que fazem uso problemático do álcool.<br>El objetivo fue conocer los factores asociados y las consecuencias del consumo de alcohol entre los estudiantes universitarios del área de la salud de la Universidade Federal do Rio Grande/RS. La muestra fue compuesta de la participación de 351 estudiantes del primer y penúltimo año de cada curso. Se ha aplicado un cuestionario socio-demográfico y el AUDIT en la recopilación de datos. En el análisis se utilizó pruebas estadísticas. Se ha encontrado que 202 (57,5%) estudiantes por lo general bebían, de eses, 196 (97,0%) tenían familiares usuarios(as) de alcohol. Según el AUDIT, la clasificación de 147 (41,8%) estudiantes fue de bajo riesgo y 49 (14,0%) de consumo problemático. Como consecuencias, fueron detectados los apagones, el coma alcohólico y los accidentes de tráfico. Se ha comprobado que 171 (48,7%) estudiantes no usaron un condón durante las últimas relaciones sexuales y 37 (10,5%) tuvieron entre tres y 10 parejas en los últimos 12 meses. Se ha evidenciado la necesidad de implementar estrategias de cuño preventivo en el ámbito universitario, para detectar de forma temprana el potencial de abuso, así como la oportunidad de tratamiento a los(las) que hacen uso problemático del alcohol.<br>It aimed to know the facts and consequences linked to alcoholic drinks among university students, in the health area at Federal University of Rio Grande/RS. The sample consisted of 351 students of the first and last year of each course. A sociodemografic questionnaire was applied and AUDIT was used in data collection. For the analyses, they were used statistical tests. It was verified that 202 (57, 5%) students would usually drink alcohol, from these, 196 (97, 0%) belonged to families where there were alcohol users. According to AUDIT, the students were sorted out in low risk 147 (41,8%) and problematic use 49 (14,0%). As consequences, were detected blackouts, alcoholic coma and car accidents. It was clear that 171 (48,7%) students did not use condom in their last sexual intercourses and 37 (10,5%) had from three to 10 sexual partners in the last 12 months. It urges the need to implement strategies of preventive nature in the university environment, so as to detect as early as possible the potential abusive use, as well as the opportunity for treatment to those who make problematic use of alcohol

Potentialities of LiTaO3 for Bulk Acoustic Wave Filters

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New Insights into the Electronic Transport of Reduced Graphene Oxide Using Scanning Electrochemical Microscopy

International audienceThe present work investigates the electronic conduction of reduced graphene oxide flakes and the coupling between flakes through a combined SECM (scanning electrochemical microscopy), AFM, and SEM analysis. Images of individual and interconnected flakes directly reveal the signature of the contact resistance between flakes in a noncontact and substrate-independent way. Quantitative evaluation of the parameters is achieved with the support of numerical simulations to interpret the experimental results. The interflakes contact resistance importantly impacts the transport of electrons, which can be anticipated as a key parameter in r-GO-based materials used in fuel cells, lithium batteries, supercapacitors, and organic electronic devices