Developments in miniaturized microscopes have enabled visualization of brain activities and structural dynamics in animals engaging in self-determined behaviors. However, it remains a challenge to resolve activity at single dendritic spines in freely behaving animals. Here, we report the design and application of a fast high-resolution, miniaturized two-photon microscope (FHIRM-TPM) that accomplishes this goal. With a headpiece weighing 2.15 g and a hollow-core photonic crystal fiber delivering 920-nm femtosecond laser pulses, the FHIRM-TPM is capable of imaging commonly used biosensors (GFP and GCaMP6) at high spatiotemporal resolution (0.64 μm laterally and 3.35 μm axially, 40 Hz at 256 × 256 pixels for raster scanning and 10,000 Hz for free-line scanning). We demonstrate the microscope's robustness with hour-long recordings of neuronal activities at the level of spines in mice experiencing vigorous body movements.

Graphene oxide (GO) flakes have been deposited to bridge the gap between two epitaxial graphene electrodes to produce all-graphene devices. Electrical measurements indicate the presence of Schottky barriers (SB) at the graphene/graphene oxide junctions, as a consequence of the band-gap in GO. The barrier height is found to be about 0.7 eV, and is reduced after annealing at 180• C, implying that the gap can be tuned by changing the degree of oxidation. A lower limit of the GO mobility was found to be 850 cm 2 /Vs, rivaling silicon. In situ local oxidation of patterned epitaxial graphene has been achieved. PACS numbers: 73.61.Ph, 73.40.Sx Inspired by the exceptional properties of carbon nanotubes, epitaxial graphene based electronics was conceived as a possible new platform for post-CMOS electronics. In contrast to carbon nanotubes, graphene layers can be patterned to produce interconnected all-carbon structures, thereby overcoming a wide variety of problems facing nanotube-based electronics. Our earlier work focused primarily on producing and characterizing device quality epitaxial graphene (EG) on silicon carbide [1,2,3,4,5]. Here we demonstrate the production and properties of the epitaxial-graphene/graphene-oxide Schottky barrier. We also successfully chemically patterned epitaxial graphene to produce seamless graphene oxide to graphene junctions, thereby dramatically enhancing epitaxial graphene electronics.We recently showed that EG can be reliably patterned over large areas to produce hundreds of functioning high mobility field effect transistors (FET) over the entire surface of a 3×4 mm chip using high k dielectrics [6]. Next steps involve patterning and tailoring the properties of EG. Conventional semiconductor devices rely on a significant band gap; graphene, by contrast, is a semimetal, which severely limits the switching potential of graphene FETs (currently the maximum off-to-on resistance ratio for EG is about 35). The high mobility of EG (up to 25,000 cm 2 /Vs) offsets this deficiency for certain specialized applications. Clearly, the versatility of graphene electronics is greatly increased by converting graphene into a semiconductor. One way to achieve this is by nanopatterning. It was predicted that the electronic structure of a nanoscopic graphene ribbon should mimic that of a carbon nanotube [7,8] and semiconducting nanopatterned graphene ribbons on exfoliated graphene flakes have been demonstrated [9,10].A far more convenient scheme is to chemically convert graphene to a semiconductor. In this Letter we demonstrate the properties of (semiconducting) graphene oxide (GO), integrated into patterned EG structures. GO, first described in 1859 [11], consists of graphene layers whose surfaces are oxidized without disrupting the hexagonal graphene topology. Impressive demonstrations of deposited single layer GO [12] spurred research into alternative methods to produce a single graphene layer, by reducing deposited GO back to graphene [13,14]. In contrast, here we are interested in the semiconductin...

We synthesized g-C3N4/nano-InVO4 heterojunction-type photocatalyts by in situ growth of InVO4 nanoparticles onto the surface of g-C3N4 sheets via a hydrothermal process. The results of SEM and TEM showed that the obtained InVO4 nanoparticles 20 nm in size dispersed uniformly on the surface of g-C3N4 sheets, which revealed that g-C3N4 sheets was probably a promising support for in situ growth of nanosize materials. The achieved intimate interface promoted the charge transfer and inhibited the recombination rate of photogenerated electron-hole pairs, which significantly improved the photocatalytic activity. A possible growth process of g-C3N4/nano-InVO4 nanocomposites was proposed based on different mass fraction of g-C3N4 content. The obtained g-C3N4/nano-InVO4 nanocomposites could achieve effective separation of charge-hole pairs and stronger reducing power, which caused enhanced H2 evolution from water-splitting compared with bare g-C3N4 sheets and g-C3N4/micro-InVO4 composites, respectively. As a result, the g-C3N4/nano-InVO4 nanocomposite with a mass ratio of 80:20 possessed the maximum photocatalytic activity for hydrogen production under visible-light irradiation.

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