Bimodal behaviour of charge carriers in graphene induced by electric double layer.

A theoretical investigation is performed into the electronic properties of graphene in the presence of liquid as a function of the contact area ratio. It is shown that the electric double layer (EDL) formed at the interface of the graphene and the liquid causes an overlap of the conduction bands and valance bands and increases the density of state (DOS) at the Fermi energy (EF). In other words, a greater number of charge carriers are induced for transport and the graphene changes from a semiconductor to a semimetal. In addition, it is shown that the dependence of the DOS at EF on the contact area ratio has a bimodal distribution which responses to the experimental observation, a pinnacle curve. The maximum number of induced carriers is expected to occur at contact area ratios of 40% and 60%. In general, the present results indicate that modulating the EDL provides an effective means of tuning the electronic properties of graphene in the presence of liquid.

Aspartate Aminotransferase and Alanine Aminotransferase Detection on Paper-Based Analytical Devices with Inkjet Printer-Sprayed Reagents.

General biochemistry detection on paper-based microanalytical devices (PADs) uses pipette titration. However, such an approach is extremely time-consuming for large-scale detection processes. Furthermore, while automated methods are available for increasing the efficiency of large-scale PAD production, the related equipment is very expensive. Accordingly, this study proposes a low-cost method for PAD manufacture, in which the reagent is applied using a modified inkjet printer. The optimal reaction times for the detection of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) are shown to be 6 and 7 min, respectively, given AST and ALT concentrations in the range of 5.4 to 91.2 U/L (R² = 0.9932) and 5.38 to 86.1 U/L (R² = 0.9944). The experimental results obtained using the proposed PADs for the concentration detection of AST and ALT in real human blood serum samples are found to be in good agreement with those obtained using a traditional spectrophotometric detection method by National Cheng Kung University hospital.

Low-energy Landau level spectrum in ABC-stacked trilayer graphene.

The low-lying Landau level (LL) properties of ABC-stacked trilayer graphene are investigated by the tight-binding (TB) model. The LL spectra exhibit an asymmetric structure around the Fermi level and three finely split LLs close to the Fermi level. The LL wave functions are described by six magnetic TB Bloch functions associated with six sublattices. These Bloch functions possess oscillation modes and localization features. An effective quantum number, which is used to define a LL, is defined by the oscillation mode of the Bloch function with the largest amplitude. The LL energies in the low-field and high-field regions exhibit different features since the trigonal warping effect strongly dominates the LL properties in the low-field region. Furthermore, the LLs do not present a simple relation between the magnetic field strength (effective quantum number) and the LL energy. A detailed comparison of the calculation with all atomic interactions taken into account and that ignoring some interlayer interactions is offered. The dissimilarities between these two calculations demonstrate that interlayer interactions strongly affect the main features of LLs and should not be ignored. The dissimilarities could be further examined by experimental measurements.