pinecone/core-2020-05-10-deduplication huggingface dataset:
A robust molecular catalyst generated in situ for photo- and electrochemical water oxidation

Water splitting is the key step towards artificial photosystems for solar energy conversion and storage in the form of chemical bonding. The oxidation of water is the bottle-neck of this process that hampers its practical utility; hence, efficient, robust, and easy to make catalytic systems based on cheap and earth-abundant materials are of exceptional importance. Herein, an in situ generated cobalt catalyst, [Co-II(TCA)(2)(H2O)(2)] (TCA=1-mesityl-1,2,3-1H-triazole-4-carboxylate), that efficiently conducts photochemical water oxidation under near-neutral conditions is presented. The catalyst showed high stability under photolytic conditions for more than 3 h of photoirradiation. During electrochemical water oxidation, the catalytic system assembled a catalyst film, which proved not to be cobalt oxide/hydroxide as normally expected, but instead, and for the first time, generated a molecular cobalt complex that incorporated the organic ligand bound to cobalt ions. The catalyst film exhibited a low overpotential for electrocatalytic water oxidation (360 mV) and high oxygen evolution peak current densities of 9 and 2.7 mA cm(-2) on glassy carbon and indium-doped tin oxide electrodes, respectively, at only 1.49 and 1.39 V ( versus a normal hydrogen electrode), respectively, under neutral conditions. This finding, exemplified on the in situ generated cobalt complex, might be applicable to other molecular systems and suggests that the formation of a catalytic film in electrochemical water oxidation experiments is not always an indication of catalyst decomposition and the formation of nanoparticles
Synthesis and characterisation of reduced graphene oxide/bismuth composite for electrodes in electrochemical Eenergy storage devices.

A reduced graphene oxide/bismuth (rGO/Bi) composite was synthesized for the first time using a polyol process at a low reaction temperature and with a short reaction time (60 °C and 3 hours, respectively). The as-prepared sample is structured with 20–50 nm diameter bismuth particles distributed on the rGO sheets. The rGO/Bi composite displays a combination of capacitive and battery-like charge storage, achieving a specific capacity value of 773 C g−1 at a current density of 0.2 A g−1 when charged to 1 V. The material not only has good power density but also shows moderate stability in cycling tests with current densities as high as 5 A g−1. The relatively high abundance and low price of bismuth make this rGO/Bi material a promising candidate for use in electrode materials in future energy storage devices
Carbon-Nanodot Solar Cells from Renewable Precursors

This is the peer reviewed version of the following article: Adam Marinovic, Lim S. Kiat, Steve Dunn, Maria-Magdalena Titirici, and Joe Briscoe, ???Carbon-Nanodot Solar Cells from Renewable Precursors???, Chemistry and Sustainability, Vol. 10 (5): 1004-1013, March 2017, which has been published in final form at https://doi.org/10.1002/cssc.201601741. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.It has recently been shown that waste biomass can be converted into a wide range of functional materials, including those with desirable optical and electronic properties, offering the opportunity to find new uses for these renewable resources. Photovoltaics is one area in which finding the combination of abundant, low-cost and non-toxic materials with the necessary functionality can be challenging. In this paper the performance of carbon nanodots derived from a wide range of biomaterials obtained from different biomass sources as sensitisers for TiO2-based nanostructured solar cells was compared; polysaccharides (chitosan and chitin), monosaccharide (d-glucose), amino acids (l-arginine and l-cysteine) and raw lobster shells were used to produce carbon nanodots through hydrothermal carbonisation. The highest solar power conversion efficiency (PCE) of 0.36 % was obtained by using l-arginine carbon nanodots as sensitisers, whereas lobster shells, as a model source of chitin from actual food waste, showed a PCE of 0.22 %. By comparing this wide range of materials, the performance of the solar cells was correlated with the materials characteristics by carefully investigating the structural and optical properties of each family of carbon nanodots, and it was shown that the combination of amine and carboxylic acid functionalisation is particularly beneficial for the solar-cell performance
An eco-friendly, tunable and scalable method for producing porous functional nanomaterials designed using molecular interactions

Despite significant improvements in the synthesis of templated silica materials, post-synthesis purification remains highly expensive and renders the materials industrially unviable. In this study we address this issue for porous bioinspired silica, developing a rapid room-temperature solution method for complete extraction of organic additives. Using elemental analysis and N2 and CO2 adsorption, we demonstrate the ability to both purify and controllably tailor the composition, porosity and surface chemistry of bioinspired silica in a single step. For the first time we have modelled the extraction using molecular dynamics, revealing the removal mechanism is dominated by surface-charge interactions. We extend this to other additive chemistry, leading to a wider applicability of the method to other materials. Finally we estimate the environmental benefits of our new method compared with previous purification techniques, demonstrating significant improvements in sustainability
Polybenzoxazine-derived N-doped carbon as matrix for powder-based electrocatalysts

In addition to catalytic activity, intrinsic stability, tight immobilization on a suitable electrode surface, and sufficient electronic conductivity are fundamental prerequisites for the long-term operation of particle- and especially powder-based electrocatalysts. We present a novel approach to concurrently address these challenges by using the unique properties of polybenzoxazine (pBO) polymers, namely near-zero shrinkage and high residual-char yield even after pyrolysis at high temperatures. Pyrolysis of a nanocubic prussian blue analogue precursor (Km Mnx [Co(CN)₆]y⋅nH₂O) embedded in a bisphenol A and aniline-based pBO led to the formation of a N-doped carbon matrix modified with MnxCoyOz nanocubes. The obtained electrocatalyst exhibits high efficiency toward the oxygen evolution reaction (OER) and more importantly a stable performance for at least 65 h
Micelle-assisted electrodeposition of mesoporous Fe-Pt smooth thin films onto various substrates and their electrocatalytic activity towards hydrogen evolution reaction

Mesoporous Fe-Pt thin films are obtained by micelle-assisted electrodeposition onto metallic substrates with dissimilar activity (namely, gold, copper, and aluminum seed layers evaporated on Si/Ti) under constant applied potential (E=-1.1 V vs. Ag/AgCl) and deposition time (600 s). The amphiphilic triblock copolymer Pluronic P-123 is used as a soft template to guide the formation of mesopores. The occurrence of pores (ca. 7 nm in diameter) with narrow size distribution, distributed evenly over the surface, is observed in all cases. Despite the applied conditions being the same, the roughness and the amount of Fe incorporated in the films are influenced by the nature of the substrate. In particular, ultra-smooth films containing a larger amount of Fe (21 wt %) are obtained when deposition takes place on the Au surface. X-ray diffraction analyses reveal that Pt and Fe are alloyed to a certain extent, although some iron oxides/hydroxides also unavoidably form. The resulting films have been tested as electrocatalysts in the hydrogen evolution reaction (HER) in alkaline media. The mesoporous Fe-rich Fe-Pt films on Au show excellent HER activity and cyclability
Effects of dynamic and non-dynamic element changes in RC and RL networks

The paper deals with the redesign of passive electric networks by changes of single dynamic and non-dynamic elements which may retain or affect the natural topology of the network. It also deals with the effect of such changes on the natural dynamics of the network, the natural frequencies. The impedance and admittance modeling for passive electrical networks is used which provides a structured, symmetric, integral-differential description, which in the special cases of RC and RL networks is reduced to matrix pencil descriptions. The transformations on the network are expressed as those preserving, or modifying the two natural topologies of the network, the impedance graph and the admittance graph topologies. For the special cases of RC and RL networks, we consider the problem of the effect of changes of a single dynamic or non-dynamic element on the natural frequencies. Using the Determinantal Assignment Framework, it is shown that the family of single parameter variation problems is reduced to equivalent Root Locus problems with the possibility of fixed modes. An explicit characterization of the fixed modes is given, and a number of interesting properties of the spectrum are derived such as the interlacing property of poles and zeros for the entire family of Root Locus problems
Output-capacitorless segmented low-dropout voltage regulator with controlled pass transistors

This article presents a low quiescent current output-capacitorless quasi-digital complementary metal-oxide-semiconductor (CMOS) low-dropout (LDO) voltage regulator with controlled pass transistors according to load demands. The pass transistor of the LDO is segmented into two smaller sizes based on a proposed segmentation criterion, which considers the maximum output voltage transient variations due to the load transient to different load current steps to find the suitable current boundary for segmentation. This criterion shows that low load conditions will cause more output variations and settling time if the pass transistor is used in its maximum size. Furthermore, this situation is the worst case for stability requirements of the LDO. Therefore, using one smaller transistor for low load currents and another one larger for higher currents, a proper trade-off between output variations, complexity, and power dissipation is achieved. The proposed LDO regulator has been designed and post-simulated in HSPICE in a 0.18¿µm CMOS process to supply a stable load current between 0 and 100¿mA with a 40¿pF on-chip output capacitor, while consuming 4.8¿µA quiescent current. The dropout voltage of the LDO is set to 200¿mV for 1.8¿V input voltage. The results reveal an improvement of approximately 53% and 25% on the output voltage variations and settling time, respectively.Peer ReviewedPostprint (author's final draft
Double-frequency buck converter as a candidate topology for integrated envelope elimination and restoration applications in power supply of RFPAs

This paper proposes the use of double-frequency (DF) buck converter architecture consisting of a merged structure of high and low frequency buck cells as a candidate topology for envelope elimination and restoration (EER) applications and integrated power supply of RF power amplifiers (RFPA) to obtain favorable tradeoffs in terms of efficiency, switching ripple, bandwidth, and tracking capability. It is shown that having two degrees of freedom in designing the DF buck helps to achieve high efficiency, low output ripples, and tracking capability with low ripples, simultaneously. A comparison analysis is done with regards to the mentioned performance indexes with the standard and three-level buck converters; in addition, the results are validated in HSPICE in BSIM3V3 0.35-µm CMOS process.Peer ReviewedPostprint (author's final draft
Window functions and sigmoidal behaviour of memristive systems

Summary: A common approach to model memristive systems is to include empirical window functions to describe edge effects and nonlinearities in the change of the memristance. We demonstrate that under quite general conditions, each window function can be associated with a sigmoidal curve relating the normalised time-dependent memristance to the time integral of the input. Conversely, this explicit relation allows us to derive window functions suitable for the mesoscopic modelling of memristive systems from a variety of well-known sigmoidals. Such sigmoidal curves are defined in terms of measured variables and can thus be extracted from input and output signals of a device and then transformed to its corresponding window. We also introduce a new generalised window function that allows the flexible modelling of asymmetric edge effects in a simple manner
MOS-only reduced-order ELIN cochlear channels: comparative performance evaluation

his paper introduces and applies practical area-reduction techniques on the analogue, externally linear-internally nonlinear, complementary metal-oxide semiconductor (CMOS) implementation of a cochlear channel. This channel is constructed on the basis of the biomimetic auditory filter called One-Zero Gammatone Filter, and it has been synthesised using ultra-low power Class-AB biquadratic filters, which employ MOS transistors that operate in their weak inversion regime. The realisation of linear capacitors with appropriately configured MOS transistors, the order reduction of the One-Zero Gammatone Filter transfer function and the employment of hyperbolic sine companding filters can lead to area reductions that range from 61.8% up to 91.9% of the original size. Comparative simulation results highlight the trade-offs between performance, linearity, noise and power consumption of the designs
Trajectory control of manipulator fed by power packets

The conventional power supply is based on a continuous flow of electricity. Electrically driven independent systems face the limitations of flexibility and efficiency of power management in a network consisting of power sources, converters, and loads. The power packet dispatching system, where electricity is transferred in a discretized form with information, is expected to remove the limitations. The system realizes a dynamic arrangement of power-line connection between power sources and loads. In this paper, we focus on its application to a manipulator. This is an example of electro-mechanical actuation in independent systems. We verify the trajectory control of the manipulator fed by power packets numerically and experimentally. The results indicate that power packets as a discretized transfer of electricity can be applied to the electro-mechanical actuation
Design and ARM-embedded implementation of a chaotic map-based multicast
  scheme for multiuser speech wireless communication

This paper proposes a chaotic map-based multicast scheme for multiuser speech
wireless communication and implements it in an ARM platform. The scheme
compresses the digital audio signal decoded by a sound card and then encrypts
it with a three-level chaotic encryption scheme. First, the position of every
bit of the compressed data is permuted randomly with a pseudo-random number
sequence (PRNS) generated by a 6-D chaotic map. Then, the obtained data are
further permuted in the level of byte with a PRNS generated by a 7-D chaotic
map. Finally, it is operated with a multiround chaotic stream cipher. The whole
system owns the following merits: the redundancy in the original audio file is
reduced effectively and the corresponding unicity distance is increased; the
balancing point between a high security level of the system and real-time
conduction speed is achieved well. In the ARM implementation, the framework of
communication of multicast-multiuser in a subnet and the Internet Group Manage
Protocol is adopted to obtain the function of communication between one client
and other ones. Comprehensive test results were provided to show the
feasibility and security performance of the whole system.Comment: 22 pages, 14 figures in International Journal of Circuit Theory and
  Applications, 201
Design of robust digitally controlled DC-DC converters in the presence of strong Interference

One of the main advantages of digital control is the ability to design more sophisticated control strategies to enable high performance dc-dc \ud
converters. One such example is a buck converter operating with a digital state-feedback controller. Previous works characterise the nonlinear dynamics of such systems under ideal operating conditions. However, in practical applications, these conditions cannot be guaranteed. The focus of this work is on the behaviour of such systems when they operate\ud
in the presence of strong interference signals. Previous works on the effect of noise have shown that intermittent operation is possible when the frequency of the noise signal is close to the switching frequency. Intermittent operation can be characterised by long periods of stable operation interspersed with periods of unstable or chaotic operation which greatly downgrade the efficiency and performance of the converter and reduce its lifetime as for example increase the current ripple or add extra AC components at its output. Typically, such behaviour is avoided by modifying the circuit parameters. However, little or no work exists on developing design guidelines in order to effect its elimination. This is the focus of this research, that is, by utilising Filippov’s theory on discontinuous differential equations, to set out a design procedure that can be applied to any dc-dc converter, to tune its controller in order to eliminate intermittent operation. As a case study, the digitally controlled buck converter with a state-feedback control law is selected
Introduction to Quantum Electromagnetic Circuits

The article is a short opinionated review of the quantum treatment of
electromagnetic circuits, with no pretension to exhaustiveness. This review,
which is an updated and modernized version of a previous set of Les Houches
School lecture notes, has 3 main parts. The first part describes how to
construct a Hamiltonian for a general circuit, which can include dissipative
elements. The second part describes the quantization of the circuit, with an
emphasis on the quantum treatment of dissipation. The final part focuses on the
Josephson non-linear element and the main linear building blocks from which
superconducting circuits are assembled. It also includes a brief review of the
main types of superconducting artificial atoms, elementary multi-level quantum
systems made from basic circuit elements.Comment: 59 pages, 14 figures. IJCTA - Special Issue on Quantum Circuit
New results on periodic symbolic sequences of second order digital filters with two’s complement arithmetic

In this article, the second order digital filter with two’s complement arithmetic in [1] is considered. Necessary conditions for the symbolic sequences to be periodic after a number of iterations are given when the filter parameters are at b=a+1 and b=-a+1. Furthermore, for some particular values of a, even when one of the eigenvalues is outside the unit circle, the system may behave as a linear system after a number of iterations and the state vector may toggle between two states or converge to a fixed point at the steady state. The necessary and sufficient conditions for these phenomena are given in this article
Chaotic behaviors of stable second-order digital filters with two’s complement arithmetic

In this paper, the behaviors of stable second-order digital filters with two’s complement arithmetic are investigated. It is found that even though the poles are inside the unit circle and the trajectory converges to a fixed point on the phase plane, that fixed point is not necessarily the origin. That fixed point is found and the set of initial conditions corresponding to such trajectories is determined. This set of initial conditions is a set of polygons inside the unit square, whereas it is an ellipse for the marginally stable case. Also, it is found that the occurrence of limit cycles and chaotic fractal pattern on the phase plane can be characterized by the periodic and aperiodic behaviors of the symbolic sequences, respectively. The fractal pattern is polygonal, whereas it is elliptical for the marginally stable case
Autonomous response of a third-order digital filter with two’s complement arithmetic realized in cascade form

In this letter, results on the autonomous response of a third-order digital filter with two’s complement arithmetic realized as a first-order subsystem cascaded by a second-order subsystem are reported. The behavior of the second-order subsystem depends on the pole location and the initial condition of the first-order subsystem, because the transient behavior is affected by the first-order subsystem and this transient response can be viewed as an excitation of the original initial state to another state. New results on the set of necessary and sufficient conditions relating the trajectory equations, the behaviors of the symbolic sequences, and the sets of the initial conditions are derived. The effects of the pole location and the initial condition of first-order subsystem on the overall system are discussed. Some interesting differences between the autonomous response of second-order subsystem and the response due to the exponentially decaying input are reported. Some simulation results are given to illustrate the analytical results
Non-linear coupled CNN models for multiscale image analysis

A CNN model of partial differential equations (PDEs) for image multiscale analysis is proposed. The model is based on a polynomial representation of the diffusivity function and defines a paradigm of polynomial CNNs,for approximating a large class of nonlinear isotropic and/or anisotropic PDEs. The global dynamics of spacediscrete polynomial CNN models is analyzed and compared with the dynamic behavior of the corresponding space-continuous PDE models. It is shown that in the isotropic case the two models are not topologically equivalent: in particular discrete CNN models allow one to obtain the output image without stopping the image evolution after a given time (scale). This property represents an advantage with respect to continuous PDE models and could simplify some image preprocessing algorithm
Digital implementation of the cellular sensor-computers

Two different kinds of cellular sensor-processor architectures are used nowadays in various\ud
applications. The first is the traditional sensor-processor architecture, where the sensor and the\ud
processor arrays are mapped into each other. The second is the foveal architecture, in which a\ud
small active fovea is navigating in a large sensor array. This second architecture is introduced\ud
and compared here. Both of these architectures can be implemented with analog and digital\ud
processor arrays. The efficiency of the different implementation types, depending on the used\ud
CMOS technology, is analyzed. It turned out, that the finer the technology is, the better to use\ud
digital implementation rather than analog
Multi-almost periodicity and invariant basins of general neural networks
  under almost periodic stimuli

In this paper, we investigate convergence dynamics of $2^N$ almost periodic
encoded patterns of general neural networks (GNNs) subjected to external almost
periodic stimuli, including almost periodic delays. Invariant regions are
established for the existence of $2^N$ almost periodic encoded patterns under
two classes of activation functions. By employing the property of
$\mathscr{M}$-cone and inequality technique, attracting basins are estimated
and some criteria are derived for the networks to converge exponentially toward
$2^N$ almost periodic encoded patterns. The obtained results are new, they
extend and generalize the corresponding results existing in previous
literature.Comment: 28 pages, 4 figure