Two-dimensional van der Waals (2D vdWs) materials are a class of new materials that can provide important resources for future electronics and materials sciences due to their unique physical properties. Among 2D vdWs materials, black phosphorus (BP) has exhibited significant potential for use in electronic and optoelectronic applications because of its allotropic properties, high mobility, and direct and narrow band gap. Here, we demonstrate a few-layered BP-based nonvolatile memory transistor with a poly(vinylidenefluoride-trifluoroethylene) (P(VDF-TrFE)) ferroelectric top gate insulator. Experiments showed that our BP-based ferroelectric transistors operate satisfactorily at room temperature in ambient air and exhibit a clear memory window. Unlike conventional ambipolar BP transistors, our ferroelectric transistors showed only p-type characteristics due to the carbon-fluorine (C-F) dipole effect of the P(VDF-TrFE) layer, as well as the highest linear mobility value of 1159 cm(2) V(-1) s(-1) with a 10(3) on/off current ratio. For more advanced memory applications beyond unit memory devices, we implemented two memory inverter circuits, a resistive-load inverter circuit and a complementary inverter circuit, combined with an n-type molybdenum disulfide (MoS2) nanosheet. Our memory inverter circuits displayed a clear memory window of 15 V and memory output voltage efficiency of 95%.

Scalable and simple methods for selective extraction of pure, semiconducting (s) single-walled carbon nanotubes (SWNTs) is of profound importance for electronic and photovoltaic applications. We report a new, one-step procedure to obtain respective large-diameter s- and metallic (m)-SWNT enrichment purity in excess of 99% and 78%, respectively, via interaction between the aromatic dispersing agent and SWNTs. The approach utilizes N-dodecyl isoalloxazine (FC12) as a surfactant in conjunction with sonication and benchtop centrifugation methods. After centrifugation, the supernatant is enriched in s-SWNTs with less carbonaceous impurities, whereas precipitate is enhanced in m-SWNTs. In addition, the use of an increased centrifugal force enhances both the purity and population of larger diameter s-SWNTs. Photoinduced energy transfer from FC12 to SWNTs is facilitated by respective electronic level alignment. Owing to its peculiar photoreduction capability, FC12 can be employed to precipitate SWNTs upon UV irradiation and observe absorption of higher optical transitions of SWNTs. A thin-film transistor prepared from a dispersion of enriched s-SWNTs was fabricated to verify electrical performance of the sorted sample and was observed to display p-type conductance with an average on/off ratio over 10(6) and an average mobility over 10 cm(2)/V·s.

Using surface type air atmospheric pressure plasma, we investigated the amount of ozone and other reactive species generation with variations of the surface temperature of an electrode through an optical emission spectrum and a tube type gas detector. Reduced version of global model (GM) was employed to complement these experimental observations. The results of the model matched well with the experimental data. The amount of ozone generated from the surface type air plasma device was dramatically reduced with increasing temperature. Atomic oxygen (O) and nitric oxide (NO) radicals, which are important agents for biomedical applications, proportionally increased with increasing temperature. We also elucidated the dominant reaction related to the generation or loss of these radicals based on temperature variation through our GM.

Two-dimensional molybdenum disulfide (MoS 2) has substantial potential as a semiconducting material for devices. However, it is commonly prepared by mechanical exfoliation, which limits flake size to only a few micrometers, which is not sufficient for processes such as photolithography and circuit patterning. Chemical vapor deposition (CVD) has thus become a mainstream fabrication technique to achieve large-area MoS 2. However, reports of conventional photolithographic patterning of large-area 2D MoS 2-based devices with high mobilities and low switching voltages are rare. Here we fabricate CVD-grown large-area MoS 2 fieldeffect transistors (FETs) by photolithography and demonstrate their potential as switching and driving FETs for pixels in analog organic light-emitting diode (OLED) displays. We spin-coat an ultrathin hydrophobic polystyrene layer on an Al 2 O 3 dielectric, so that the uniformity of threshold voltage (V th) of the FETs might be improved. Our MoS 2 FETs show a high linear mobility of approximately 10 cm 2 V −1 s −1 , due to a large grain size around 60 μm, and a high ON/OFF current ratio of 10 8. Dynamic switching of blue and green OLED pixels is shown at~5 V, demonstrating their application potential.

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The effects of pentoxifylline (PTX), a drug commonly used for vascular disorders in humans, on the pO2 in SCK tumors of A/J mice and FSa-II tumors of C3Heb/FeJ mice as well as on the radioresponse of SCK tumors were investigated. When the host mice were injected intraperitoneally (ip) with 5 mg/kg PTX, the tumor pO2 increased slowly, peaked 20-50 min postinjection, and returned to its original level in 70-90 min. The magnitude of the increase in tumor pO2 varied markedly depending on the site and tumors. The magnitude of the changes in tumor pO2 after an ip injection of 25 or 50 mg/kg PTX was similar to that caused by 5 mg/kg PTX, but the pO2 tended to remain elevated longer with the higher dose of PTX. When the A/J mice bearing SCK tumors in the legs were injected ip with 50 mg/kg PTX and the tumors were X-irradiated 20 min later, the radiation-induced growth delay of the tumors was greater than that caused by X irradiation alone. The present study demonstrated that PTX is potentially useful for increasing the pO2 and the radioresponse of human tumors.

Two-dimensional (2D) semiconductors, such as transition metal dichalcogenides (TMDs) and black phosphorus, are the most promising channel materials for future electronics because of their unique electrical properties. Even though a number of 2D-materials-based logic devices have been demonstrated to date, most of them are a combination of more than two unit devices. If logic devices can be realized in a single channel, it would be advantageous for higher integration and functionality. In this study we report high-performance van der Waals heterostructure (vdW) ReS 2 transistors with graphene electrodes on atomically flat hBN, and demonstrate a NAND gate comprising a single ReS 2 transistor with split gates. Highly sensitive electrostatic doping of ReS 2 enables fabrication of gate-tunable NAND logic gates, which cannot be achieved in bulk semiconductor materials because of the absence of gate tunability. The vdW heterostructure NAND gate comprising a single transistor paves a novel way to realize “all-2D” circuitry for flexible and transparent electronic applications.

The formation of secondary energetic electrons induced by an abnormal electron-heating mode in pulsed microwave-frequency atmospheric microplasmas was investigated using particle-in-cell simulation. We found that additional high electron heating only occurs during the first period of the ignition phase after the start of a second pulse at sub-millimeter dimensions. During this period, the electrons are unable to follow the abruptly retreating sheath through diffusion alone. Thus, a selfconsistent electric field is induced to drive the electrons toward the electrode. These behaviors result in an abnormal electron-heating mode that produces high-energy electrons at the electrode with energies greater than 50 eV. V C 2014 AIP Publishing LLC. [http://dx.