Improvement of cyclability of silicon-containing carbon nanofiber anodes for lithium-ion batteries by employing succinic anhydride as an electrolyte additive

Si/C composite nanofibers were prepared by electrospinning and carbonization using polyacrylonitrile as the spinning medium and carbon precursor. The effect of electrolyte additive succinic anhydride (SA) on the electrochemical performance of Si/C composite nanofiber anodes was investigated. Results show that after 50 cycles, the discharge capacity of Si/C composite nanofiber anode with the SA-added electrolyte is 34 % higher than that with additive-free electrolyte. At 150th cycle, the capacity retention of Si/C composite nanofiber anode with SA-added electrolyte is 82 % under 70 % state-of-charge. It is demonstrated that adding additive SA in the electrolyte is an effective and economic way to improve the cyclability of high-capacity Si/C composite nanofibers for next-generation high-energy lithium-ion batteries.     

Nanophosphor aluminum oxide: Luminescence response of a potential dosimetric material

This work reports on the investigation of the radiation dosimetry properties of Al₂O₃ nanopowders. Samples were produced by solution combustion synthesis using three different organic fuels to check for the effect of synthesis conditions on the properties of interest. Luminescence characteristics were studied by thermoluminescence and optically stimulated luminescence (OSL) techniques. We found that samples produced using urea have characteristics similar to bulk Al₂O₃:C and may be suitable for personal dosimetry, while samples produced using glycine and hexamethylenetetramine (HMT) may be more suitable for applications where fast OSL decay is advantageous. While these results are promising and warrant further investigation, much has to be done to overcome the greatly decreased luminescence intensity of the nanomaterials as compared to bulk Al₂O₃:C.     

Response to “The Mössbauer rotor experiment and the general theory of relativity” by C. Corda

We show that a new attempt by Corda (2016), just like his previous attempt (Corda, 2015) that we had answered before (A.L. Kholmetskii et al., 2015), to reinterpret Mössbauer experiments in a rotating system as a “new, strong and independent proof of the correctness of Einstein’s vision of gravity” is erroneous. In addition, we demonstrate that Corda’s criticism of Yarman–Arik–Kholmetskii gravitation theory (in short YARK), is based on the application of ill-posed logic; thus rendering his claims against YARK as unfounded.     

Structural and electronic properties of zincblende phase of Tl x Ga1−x As y P1−y quaternary alloys: First-principles study

Using the first-principles band-structure method, we have calculated the structural and electronic properties of zincblende TlAs, TlP, GaAs and GaP compounds and their new semiconductor Tl _x Ga_1?x As _y P_1?y quaternary alloys. Structural properties of these semiconductors are obtained with the Perdew and Wang local-density approximation. The lattice constants of Tl _x Ga_1?x As, Tl _x Ga_1?x P ternary and Tl _x Ga_1?x As _y P_1?y quaternary alloys were composed by Vegard’s law. Our investigation on the effect of the doping (Thallium and Arsenic) on lattice constants and band gap shows a non-linear dependence for Tl _x Ga_1?x As _y P_1?y quaternary alloys. The band gap of Tl _x Ga_1?x As _y P_1?y , E _g (x, y) concerned by the compositions x and y. To our awareness, there is no theoretical survey on Tl _x Ga_1?x As _y P_1?y quaternary alloys and needs experimental verification.     

Trajectory tracking control of parallel robots in the presence of joint drive flexibility

Trajectory tracking control of parallel manipulators is aimed in the presence of flexibility at the joint drives. Joint structural damping is also considered in the dynamic model. The system is first converted into an open-tree structure by disconnecting a sufficient number of unactuated joints. The closed loops are then expressed by constraint equations. It is shown that, in a parallel robot with flexible joint drives, the acceleration level inverse dynamics equations are singular because the control torques do not have an instantaneous effect on the end-effector accelerations due to the elastic media. Eliminating the Lagrange multipliers and the intermediate variables, a fourth-order input–output relation is obtained between the actuator torques and the end-effector position variables. The proposed control law decouples and linearizes the system and achieves asymptotic stability by feedback of positions and velocities of the actuated joints and rotors. As a case study, a three degree of freedom, two legged planar parallel manipulator is simulated to illustrate the performance of the method. The end-effector desired trajectory is chosen such that the kinematic and drive singular positions are avoided.     

Physical Limitations on Fundamental Efficiency of SET-Based Brownian Circuits

Brownian circuits are based on a novel computing approach that exploits quantum fluctuations to increase the efficiency of information processing in nanoelectronic paradigms. This emerging architecture is based on Brownian cellular automata, where signals propagate randomly, driven by local transition rules, and can be made to be computationally universal. The design aims to efficiently and reliably perform primitive logic operations in the presence of noise and fluctuations; therefore, a Single Electron Transistor (SET) device is proposed to be the most appropriate technology-base to realize these circuits, as it supports the representation of signals that are token-based and subject to fluctuations due to the underlying tunneling mechanism of electric charge. In this paper, we study the physical limitations on the energy efficiency of the Single-Electron Transistor (SET)-based Brownian circuit elements proposed by Peper et al. using SIMON 2.0 simulations. We also present a novel two-bit sort circuit designed using Brownian circuit primitives, and illustrate how circuit parameters and temperature affect the fundamental energy-efficiency limitations of SET-based realizations. The fundamental lower bounds are obtained using a physical-information-theoretic approach under idealized conditions and are compared against SIMON 2.0 simulations. Our results illustrate the advantages of Brownian circuits and the physical limitations imposed on their SET-realizations.     

Stalling chromophore synthesis of the fluorescent protein Venus reveals the molecular basis of the final oxidation step

Fluorescent proteins (FPs) have revolutionised the life sciences, but the mechanism of chromophore maturation is still not fully understood. Here we show that incorporation of a photo-responsive non-canonical amino acid within the chromophore stalls maturation of Venus, a yellow FP, at an intermediate stage; a crystal structure indicates the presence of O₂ located above a dehydrated enolate form of the imidazolone ring, close to the strictly conserved Gly67 that occupies a twisted conformation. His148 adopts an “open” conformation so forming a channel that allows O₂ access to the immature chromophore. Absorbance spectroscopy supported by QM/MM simulations suggests that the first oxidation step involves formation of a hydroperoxyl intermediate in conjunction with dehydrogenation of the methylene bridge. A fully conjugated mature chromophore is formed through release of H₂O₂, both in vitro and in vivo. The possibility of interrupting and photochemically restarting chromophore maturation and the mechanistic insights open up new approaches for engineering optically controlled fluorescent proteins.

Fluorescent proteins (FPs) have revolutionised the life sciences, but the chromophore maturation mechanism is still not fully understood. Here we photochemically trap maturation at a crucial stage and structurally characterise the intermediate.