Expanding applications for microelectronics in large-area sensor arrays, disposable sensor tapes, timeϪtemperature smart labels, radio frequency identification tags, and roll-up displays 1Ϫ4 motivate efforts to integrate electronics onto flexible plastic, paper, or metal substrates. A principal strategy for achieving flexible electronics is to employ graphic arts methods such as flexographic or ink-jet printing to pattern metallic, semiconducting, and insulating inks onto foils and paper. 5Ϫ10 Liquid phase printing offers the potential for high-throughput roll-toroll or sheet-to-sheet processing of electronics on large-area substrates, facilitating applications where large areas are necessary (e.g., displays) and also potentially translating into low production cost. Yet the challenge for printed electronics is to achieve high-performance circuits. The inherently low carrier mobilities of many printable organic or nanoparticle-based semiconductors lead to reduced transistor switching frequencies and high circuit supply voltages. Alternative strategies in which silicon chips are bonded to flexible substrates (by transfer printing or pick-andplace methods) are also attractive because they benefit from the superior electronic properties of silicon and the very advanced state of silicon microelectronics technology.11 In a competitive environment, the success of liquid phase printed electronics depends on substantial performance improvements, in particular, the development of faster, lower power printed circuits. Figure 1a displays a summary of reported signal delay times versus supply voltages for ring oscillator circuits based on organic semiconductors and carbon nanotube (CNT) arrays. It is evident that for nonprinted organic ring oscillators (open blue symbols) signal delays of 1Ϫ10 s have been achieved but only for supply voltages of 10Ϫ100 V, 12Ϫ24 while for supply voltages in the range of 4Ϫ10 V, the delay is above 10 s for the fastest circuits, with most displaying Ͼ1 ms switching times.25Ϫ28 Reports of printed ring oscillators are less common (solid green symbols in Figure 1a), and these circuits have generally required tens of volts to achieve switching times on the order of 1 ms.29Ϫ32 Such large voltages are not practical for many potential applications of flexible electronics where power will be supplied by thin-film batteries or radio frequency fields. Very recently, unipolar, p-type electrolyte-gated ring oscillator circuits have been demonstrated that indeed operate at very low

Single doses of resveratrol have previously been shown to increase cerebral blood flow (CBF) with no clear effect on cognitive function or mood in healthy adults. Chronic resveratrol consumption may increase the poor bioavailability of resveratrol or otherwise potentiate its psychological effects. In this randomised, double-blind, placebo-controlled, parallel-groups study, a total of sixty adults aged between 18 and 30 years received either placebo or resveratrol for 28 d. On the 1st and 28th day of treatment, the performance of cognitively demanding tasks (serial subtractions, rapid visual information processing and 3-Back) (n 41 complete data sets) was assessed, alongside blood pressure (n 26) and acute (near-IR spectroscopy (NIRS)) and chronic (transcranial Doppler) measures of CBF (n 46). Subjective mood, sleep quality and health questionnaires were completed at weekly intervals (n 53/54). The results showed that the cognitive effects of resveratrol on day 1 were restricted to more accurate but slower serial subtraction task performance. The only cognitive finding on day 28 was a beneficial effect of resveratrol on the accuracy of the 3-Back task before treatment consumption. Subjective ratings of 'fatigue' were significantly lower across the entire 28 d in the resveratrol condition. Resveratrol also resulted in modulation of CBF parameters on day 1, as assessed by NIRS, and significantly increased diastolic blood pressure on day 28. Levels of resveratrol metabolites were significantly higher both before and after the day's treatment on day 28, in comparison with day 1. These results confirm the acute CBF effects of resveratrol and the lack of interpretable cognitive effects.

We study one-dimensional systems with random diagonal disorder but off-diagonal short-range correlations imposed by structural constrains. We find that these correlations generate effective conduction channels for finite systems. At a certain golden correlation condition for the hopping amplitudes, we find an extended state for an infinite system. Our model has important implications to charge transport in DNA molecules, and a possible set of experiments in semiconductor superlattices is proposed to verify our most interesting theoretical predictions.

Tearing mode instability is one of the most important dynamic processes in space and laboratory plasmas. Hall effects, resulted from the decoupling of electron and ion motions, could cause the fast development and perturbation structure rotation of the tearing mode and become non-negligible. A high accuracy nonlinear MHD code (CLT) is developed to study Hall effects on the dynamic evolution of tearing modes with Tokamak geometries. It is found that the diamagnetic rotation of the mode structure is self-consistently contained in the Hall MHD model. The self-consistently generated rotation largely alters the dynamic behaviors of the double tearing mode.

No abstract

This study reports a simple, rapid, low-cost, robust, and multiplexed barcoded paper-based assay (BPA) compatible with mobile devices. An inkjet printer and an XYZ dispensing platform were used to realize mass-manufacturing of barcoded paper-based analytical devices (BPADs) with high precision and efficiency. We designed a new group of barcodes and developed an application (APP) for the reading of the new code. The new barcodes possess a 16 times higher coding capacity than the standard Codabar code in our experiment on drug residue detection. The BPA system allows applications in the assays of blood-transmitted infections, drug residues in milk and multiplex nucleic acids. The whole detection process and the readout of the results can be completed within 10 minutes. The limit of detection for enrofloxacin (ENR) (8 ng mL) satisfies the requirements of drug residue monitoring. Its high rapidity, simplicity, efficiency and selectivity make the BPA system extremely suitable to be applied in rapid and on-site detection.

The combination of self-assembly (bottom up) and nano-imprint lithography (top down) is an efficient and effective way to record information at the nanoscale by writing. The use of an electron beam for writing is quite a promising strategy; however, the 'paper' on which to save the information is not yet fully realized. Herein, graphene was selected as the thinnest paper for recording information at the nanoscale. In a transmission electron microscope, in situ high precision writing and drawing were achieved on graphene nanosheets by manipulating electrons with a 1 nm probe (probe current ~2 × 10(-9) A m(-2)) in scanning transmission electron microscopy (STEM) mode. Under electron probe irradiation, the carbon atom tends to displace within a crystalline specimen, and dangling bonds are formed from the original sp(2) bonding after local carbon atoms have been kicked off. The absorbed random foreign amorphous carbon assembles along the line of the scanning direction induced by secondary electrons and is immobilized near the edge. With the ultralow secondary electron yield of the graphene, additional foreign atoms determining the accuracy of the pattern have been greatly reduced near the targeting region. Therefore, the electron probe in STEM mode serves as invisible ink for nanoscale writing and drawing. These results not only shed new light on the application of graphene by the interaction of different forms of carbon, but also illuminate the interaction of different carbon forms through electron beams.

Intense AC electric fields on semiconductor structures have been studied in photon-assisted tunneling experiments with magnetic field applied either parallel (B ) or perpendicular (B ⊥ ) to the interfaces. We examine here the electron dynamics in a double quantum well when intense AC electric fields F , and tilted magnetic fields are applied simultaneously. The problem is treated non-perturbatively by a time-dependent Hamiltonian in the effective mass approximation, and using a Floquet-Fourier formalism. For B = 0, the quasi-energy spectra show two types of crossings: those related to different Landau levels, and those associated to dynamic localization (DL), where the electron is confined to one of the wells, despite the non-negligible tunneling between wells. B couples parallel and in-plane motions producing anti-crossings in the spectrum. However, since our approach is non-perturbative, we are able to explore the entire frequency range. For high frequencies ω, we reproduce the well known results of perfect DL given by zeroes of a Bessel function. We find also that the system exhibits DL at the same values of the field F , even as B = 0, suggesting a hidden dynamical symmetry in the system which we identify with different parity operations. Symmetries under general parity operations explain many of the features in the spectra, and their overall behavior under magnetic field. The return times for the electron at various values of field exhibit interesting and complex behavior which is also studied in detail. We find that smaller ω shifts the DL points to lower eF d/ ω ratios, and more importantly, yields poorer (less effective) localization by the field, while other states change also physical character. We analyze the explicit time evolution of the system, monitoring the elapsed time to return to a given well for each Landau level, and find non-monotonic behavior for decreasing frequencies.