Lithium Ion Battery Materials as Tunable, Redox Non-Innocent Catalyst Supports

The development of general strategies for the electronic tuning of a catalyst’s active site is an ongoing challenge in heterogeneous catalysis. To this end, herein we describe the application of Li-ion battery cathode and anode materials as redox non-innocent catalyst supports that can be continuously modulated as a function of lithium intercalation. A zero-valent nickel complex was oxidatively grafted onto the surface of lithium manganese oxide (LixMn2O4) to yield isolated Ni(II) occupying the vacant interstitial octahedral site in the Li diffusion channel on the surface and subsurface of the spinel structure (Ni/LixMn2O4). The activity of Ni/LixMn2O4 for olefin hydrogenation, as a representative probe reaction, was found to increase monotonically as a function of support reductive lithiation. Simulation of Ni/LixMn2O4 reveals the dramatic impact of surface redox states on the viability of the homolytic oxidative addition mechanism for H2 activation. Catalyst control through support lithiation was extended to an organotantalum complex on LixTiO2, demonstrating the generality of this phenomenon.

Floating Memristor and Inverse Memristor Emulators with Electronic Tuning

The work reports two different configurations to emulate the floating memristor and inverse memristor behavior. The presented circuits are based on a modified concept of active element VDTA (Voltage Differencing Transconductance Amplifier) termed as MVDTA. The reported floating memristor employs only a single MVDTA and single grounded capacitance. On the other end, the floating emulation circuit of inverse memristor emulator is based on two MVDTAs and single grounded capacitance. The behavior of the realized element for both the configurations can be tuned electronically through biasing voltage. Also, there is no employment of any commercial IC or external circuitry for multiplication of analogue voltages which is generally required to implement memristive elements. Along with the circuit implementations, mathematical properties of ideal memristor and inverse memristor considering both symmetric as well as nonsymmetric models are discussed. All the emulation circuits are verified by executing simulations using CMOS 0.18[Formula: see text]um process technique under PSPICE environment. The reported circuits are also realized using commercially available IC LM13700 and results are presented.

Voltage Differencing Current Conveyor Based Voltage-Mode and Current-Mode Universal Biquad Filters with Electronic Tuning Facility

The objective of this study is to present four new universal biquad filters, two voltage-mode multi-input-single-output (MISO), and two current-mode single-input-multi-output (SIMO). The filters employ one voltage differencing current conveyor (VDCC) as an active element and two capacitors along with two resistors as passive elements. All the five filter responses, i.e., high-pass, low-pass, band-pass, band-stop, and all-pass responses, are obtained from the same circuit topology. Moreover, the pole frequency and quality factor are independently tunable. Additionally, they do not require any double/inverted input signals for response realization. Furthermore, they enjoy low active and passive sensitivities. Various regular analyses support the design ideas. The functionality of the presented filters are tested by PSPICE simulations using TSMC 0.18 µm technology parameters with ± 0.9 V supply voltage. The circuits are also justified experimentally by creating the VDCC block using commercially available OPA860 ICs. The experimental and simulation results agree well with the theoretically predicted results.