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Novel porous flower-like NiO@graphene composites with superior microwave absorption properties dues to good impedance matching, the special porous flower-like structure, polarization effects and conductivity loss.

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Tiras de papel de filtro combinadas com eletrodos de carbono impresso (SPCE) foram usadas na montagem de um dispositivo microfluídico para detecção de Pb(II) and Cd(II) em soluções aquosas. O dispositivo microfluídico portátil (com detecção eletroquímica direta) foi testado na quantificação direta de analitos (Pb(II) e Cd(II)) em amostras aquosas contaminadas sem pré-tratamentos. O sinal voltamétrico de redissolução anódica de onda quadrada (SWASV) foi bastante intensificado e apresentou excelente desempenho analítico na detecção de Pb(II) e Cd(II) (de 0 a 100 ppb) com baixo limite de detecção (2,0 e 2,3 ppb, respectivamente). Os dispositivos eletroquímicos propostos também apresentaram boa seletividade e estabilidade para análises de amostras reais de refrigerante e água subterrânea com contaminação física. O dispositivo é simples, de baixo custo, fácil fabricação e portátel. Este dispositivo analítico tem a possibilidade de ser útil em aplicações do tipo point-of-care no monitoramento ambiental, na saúde pública e na segurança alimentar.Filter paper strips combined with screen-printed carbon electrodes (SPCE) were used in the assembly of a microfluidic device for detecting Pb(II) and Cd(II) in aqueous samples. The portable microfluidic device (with direct electrochemical detection) was tested for direct quantification of multiple analytes (Pb (II) and Cd(II)) in contaminated aqueous samples without pretreatment. Square wave anodic stripping voltammetric (SWASV) signal was greatly enhanced and displayed excellent analytical performance for Pb(II) and Cd(II) detection (from 0 to 100 ppb) with low limit of detection of 2.0 and 2.3 ppb, respectively. The proposed electrochemical devices also exhibited good selectivity and stability for analyses of real samples of gas dissolved salty soda water and ground water with physical contamination. The device is simple, low-cost, easy-to-fabricate and portable. This analytical device has the possibility of being useful for point-of-care applications in environmental monitoring, public health and food safety.Keywords: microfluidic devices, screen-printed carbon electrodes, filter paper strip, portable device IntroductionAnalytical instrumentations tend to be miniaturization and intellectualization for in situ applications.1-4 Therefore, it can be convenient for real-time and on-line monitoring in the fields of environmental monitoring, biomedical science, agriculture, military analysis and industrial process monitoring, etc. Paper represents a great and useful supporting material for developing sensing devices owing to its various unique advantages, such as inexpensive, easy-printed, biodegradable and the porous structure facilitates lateral-flow assays suitable for chromatographic separations and as good filter.5-8 Screen-printing technology can be easily applied to the mass production of inexpensive, reproducible and sensitive disposable electrodes. 9,10Paper-based micro-electrochemical device integrated screen-printed carbon electrodes (SPCE) can meet the requirements fo...

Fe ions doped SnO2/MWCNTs composites with 48.8% Fe ions doping content showed the maximum reflection loss was −44.54 dB at 15.44 GHz, and the maximum absorption bandwidth of reflection loss below −10 dB was 4.5 GHz in the Ku band.