RESUMO
OBJECTIVES: The study investigated effects of electrode material, inter-electrode distance (IED), and conductive gel on electromyographic (EMG) activity recorded from the masseter muscle. MATERIALS AND METHODS: EMG was recorded unilaterally, as ten volunteers performed standardized oral tasks. Ag/AgCl and Ag coated with Au were the gel-based; Ag alloy coated with graphene, pure Ag coated with graphene and silver nanowire embedded electrodes were the gel-free materials tested. Ag/AgCl electrodes were tested at three different IEDs (i.e. 15 mm, 20 mm, 25 mm). An electrode relative performance index (ERPI) was defined and calculated for each of the standardized oral tasks that the volunteers performed. ERPI values obtained for the different oral tasks with different electrode materials and IEDs were compared using two-way repeated-measures ANOVA. RESULTS: ERPI values were not significantly influenced by IED. However, for the electrode materials statistically significant differences were found in ERPI values for all oral tasks. Of the gel-free electrode materials tested, pure silver electrodes coated with graphene had the highest ERPI values followed by Ag alloy electrodes coated with graphene and silver nanowire embedded electrodes. CONCLUSIONS: Within the limitations of the study, IED between 15 and 25 mm has a negligible effect on masseter muscle EMG. Graphene coated and silver nanowire embedded electrodes show promise as gel-free alternatives.
Assuntos
Eletromiografia/instrumentação , Eletromiografia/métodos , Músculo Masseter/fisiologia , Nanofios , Dispositivos Eletrônicos Vestíveis , Adulto , Força de Mordida , Eletrodos/normas , Feminino , Grafite/normas , Humanos , Masculino , Mastigação/fisiologia , Nanofios/normas , Prata/normas , Dispositivos Eletrônicos Vestíveis/normas , Adulto JovemRESUMO
We describe the construction of temperature-light gradient incubator with a novel material: a thermally-conductive graphite foam that is lightweight, chemically resistant, economically competitive with metal, and much cheaper to fabricate. We combined this material with a variable-intensity LED light array to construct a low-cost light-temperature gradient incubator, and demonstrate its use for studies of microbial growth, enrichment, and isolation.
Assuntos
Incubadoras/normas , Luz , Microbiologia/instrumentação , Temperatura , Eucariotos/crescimento & desenvolvimento , Eucariotos/fisiologia , Grafite/química , Grafite/economia , Grafite/normas , Incubadoras/economia , Microbiologia/economiaRESUMO
In this paper, we review the recent extraordinary progress in the development of a new quantum standard for resistance based on graphene. We discuss the unique properties of this material system relating to resistance metrology and discuss results of the recent highest-ever precision direct comparison of the Hall resistance between graphene and traditional GaAs. We mainly focus our review on graphene expitaxially grown on SiC, a system which so far resulted in the best results. We also briefly discuss progress in the two other graphene material systems, exfoliated graphene and chemical vapour deposition graphene, and make a critical comparison with SiC graphene. Finally, we discuss other possible applications of graphene in metrology.
Assuntos
Impedância Elétrica , Grafite/química , Grafite/normas , Modelos Químicos , Teoria Quântica , Simulação por Computador , Valores de ReferênciaRESUMO
Pencil lead is shown to be an effective matrix and calibrant in matrix-assisted laser desorption/ionisation (MALDI) mass spectrometry. Various groups of analytes, including peptides, polymers and actinide metals, can be readily ionised using MALDI when deposited onto a pencil lead matrix. The matrix is seen to have advantages in sample preparation relating to its hydrophobic properties and almost complete suppression of the matrix during analysis. Using pencil lead as a matrix is a quick and convenient method of qualitative analysis and has been shown to be quantitative for the isotope ratio analysis of actinide metals.