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Today there is a strong interest in the scientific and industrial community concerning the use of biopolymers for electronic applications, mainly driven by low-cost and disposable applications. Adding to this interest, we must recognize the importance of the wireless auto sustained and low energy consumption electronics dream. This dream can be fulfilled by cellulose paper, the lightest and the cheapest known substrate material, as well as the Earth's major biopolymer and of tremendous global economic importance. The recent developments of oxide thin film transistors and in particular the production of paper transistors at room temperature had contributed, as a first step, for the development of disposable, low cost and flexible electronic devices. To fulfil the wireless demand, it is necessary to prove the concept of self powered devices. In the case of paper electronics, this implies demonstrating the idea of self regenerated thin film paper batteries and its integration with other electronic components. Here we demonstrate this possibility by actuating the gate of paper transistors by paper batteries. We found that when a sheet of cellulose paper is covered in both faces with thin layers of opposite electrochemical potential materials, a voltage appears between both electrodes - paper battery, which is also self-regenerated. The value of the potential depends upon the materials used for anode and cathode. An open circuit voltage of 0.5V and a short-circuit current density of 1μA/cm2 were obtained in the simplest structure produced (Cu/paper/Al). For actuating the gate of the paper transistor, seven paper batteries were integrated in the same substrate in series, supplying a voltage of 3.4V. This allows proper ON/OFF control of the paper transistor. Apart from that transparent conductive oxides can be also used as cathode/anode materials allowing so the production of thin film batteries with transparent electrodes compatible with flexible, invisible, self powered and wireless electronics. © 2011 SPIE.

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Summary: In this paper we consider the monoid $\mathcal {OR}_{n}$ of all full transformations on a chain with $n$ elements that preserve or reverse the orientation, as well as its submonoids $\mathcal {OD}_{n}$ of all order-preserving or order-reversing elements, $\mathcal {OP}_{n}$ of all orientation-preserving elements and $\mathcal {O}_{n}$ of all order-preserving elements. By making use of some well known presentations, we show that each of these four monoids is a quotient of a bilateral semidirect product of two of its remarkable submonoids.

A new approach is laid out to investigate two-photon atomic transitions. It is based on the application of the finite-basis solutions constructed from the Bernstein polynomial (B-polynomial) sets. We show that such an approach provides a very promising route for the relativistic second-order (and even higher-order) calculations since it allows for analytical evaluation of the involved matrices elements. In order to illustrate possible applications of the method and to verify its accuracy, detailed calculations are performed for the 2 s 1/2 ‚Üí 1 s 1/2 transition in neutral hydrogen and hydrogen-like ions, which are compared with the theoretical predictions based on the well-established B-spline basis-set approach.

A new approach is laid out to investigate two-photon atomic transitions. It is based on the application of the finite-basis solutions constructed from the Bernstein polynomial (B-polynomial) sets. We show that such an approach provides a very promising route for the relativistic second-order (and even higher-order) calculations since it allows for analytical evaluation of the involved matrices elements. In order to illustrate possible applications of the method and to verify its accuracy, detailed calculations are performed for the 2 s 1/2 ‚Üí 1 s 1/2 transition in neutral hydrogen and hydrogen-like ions, which are compared with the theoretical predictions based on the well-established B-spline basis-set approach.

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Indium doped, and undoped, zinc oxide films were deposited using aerosol assisted chemical vapour deposition (AACVD) at atmospheric pressure on glass substrates. Electrical measurements (I-V) showed a reduction in resistivity following the addition of indium, and XRD analysis revealed an associated switch to c-axis preferred crystal orientation. The ability of the films to oxidise organic material on their surface was analysed using stearic acid as the model contaminant under ultra-violet (UV, 365 nm) irradiation. The In-doped films displayed a greater rate of organic decomposition, which we attribute to the formation of a platelet surface structure having a larger surface area than the undoped films, on which the UV generated electrons and holes may react to form active photocatalytic species. In addition we suggest that the switch to c-axis crystal orientation may reduce the electron-hole pair recombination rate at the grain boundaries, due to an improvement in crystallinity and related reduction in carrier scattering losses, leading to an increase in photocatalytic organic decomposition rate. © 2011 Elsevier B.V. All rights reserved.

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A complementary metal oxide semiconductor (CMOS) device is described. The device is based on n-(In-Ga-Zn-O) and p-type (SnO x) active oxide semiconductors and uses a transparent conductive oxide (In-Zn-O) as gate electrode that sits on a flexible, recyclable paper substrate that is simultaneously the substrate and the dielectric. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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A DC-DC step-up micro power converter for solar energy harvesting applications is presented. The circuit is based on a switched-capacitor voltage tripler architecture with MOSFET capacitors, which results in an, area approximately eight times smaller than using MiM capacitors for the 0.131 mu m CMOS technology. In order to compensate for the loss of efficiency, due to the larger parasitic capacitances, a charge reutilization scheme is employed. The circuit is self-clocked, using a phase controller designed specifically to work with an amorphous silicon solar cell, in order to obtain the maximum available power from the cell. This will be done by tracking its maximum power point (MPPT) using the fractional open circuit voltage method. Electrical simulations of the circuit, together with an equivalent electrical model of an amorphous silicon solar cell, show that the circuit can deliver a power of 1132 mu W to the load, corresponding to a maximum efficiency of 66.81%.

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