Synthesis of biologically active cadmium (II) complex with tridentate N2O donor Schiff base: DFT study, binding mechanism of serum albumins (bovine, human) and fluorescent nanowires

The photophysical properties of luminescent tetra-coordinated cadmium (II) complex formulated as [Cd(L)Cl],HL = (1-[(3-methyl-pyridine-2-ylimino)-methyl]-naphthalen-2-ol) were synthesized and characterized by analytical and spectroscopic methods. The density function theory calculations are used to investigate the electronic structures of the ligand and its complex. The interactions of cadmium (II) complex towards bovine serum albumin (BSA) and human serum albumin (HSA) were investigated using absorption and fluorescence spectroscopic techniques at pH 7.4. The quenching constants, binding constants and number of binding sites were determined by fluorescence quenching method. The calculated thermodynamic parameters (ΔG, ΔH, and ΔS) confirmed that the binding reaction is mainly entropy-driven and hydrophobic forces played an important role in the reaction. Here, we proposed a new synthetic procedure for the preparation of BSA and HSA with cadmium complex nanowires. The scanning electron microscopy images show that BSA and HSA with cadmium complex product are wire-like in structure. The complex shows enhanced antibacterial activity compared with the free ligand and standard antibiotic chloramphenicol. Antioxidant studies showed that the complex has significant antioxidant activity against DPPH. The obtained IC50 value of the DPPH activity for complex (IC50 = 138 μg/ml) showed excellent scavenging property compared to standard ascorbic acid

A Flexible Discontinuous Modulation Scheme with Hybrid Capacitor Voltage Balancing Strategy for Three-Level NPC Traction Inverter

Multilevel inverters are now-a-days being applied in electric vehicles (EV). Considering the dynamic operating conditions of an EV propelled by an induction motor, this paper proposes a flexible discontinuous modulation strategy for three-level neutral-point-clamped (NPC) inverter that can shift modulation pattern seamlessly from sinusoidal pulsewidth modulation (SPWM) to discontinuous PWM (DPWM). The modulation scheme is generalized at each degree of discontinuity to ensure minimum switching losses for variable load power factors. Additionally, a hybrid voltage balancing strategy, which comprises two sets of compensating offset signals with complementary features, has been introduced to mitigate voltage deviation problem at neutral point of the inverter. The unique feature of the proposed hybrid balancing approach is that it generates uniform compensating neutral current regardless of the level of discontinuity. This results in identical and predictable voltage balancing dynamics for the entire modulation transition covering SPWM and DPWM. It has been shown that the proposed hybrid balancing strategy does not lose its unbalance compensation strength even during transition from one modulation pattern to another. The effectiveness of the proposed scheme for wide variations in operating conditions is studied through extensive simulation, and validated in experimentation using a prototype NPC inverter with induction motor loads

An Improved Adjustable Modulation Strategy for Three-Level NPC Inverters Considering Dynamic Loading Applications

Three-level neutral-point-clamped (NPC) inverters are being widely adopted in low-voltage low-power applications. For an intended application, the modulation strategy and the operating conditions are the two key factors that highly influence the major performance indices of the NPC inverter, such as efficiency, harmonic distortion, and voltage oscillations at neutral point (NP). Considering dynamic loading applications where the operating point varies significantly, this paper proposes an improved adjustable pulsewidth modulation (PWM) strategy for a three-level NPC inverter that can alter its modulation pattern to meet desired performance objectives for the full operation range. It has been shown that by varying two control parameters namely discontinuity control parameter and bias control parameter, the proposed modulation strategy changes its pattern between the most efficient generalized discontinuous PWM to NP oscillations-free partial dipolar PWM strategy. Additionally, to obtain a tradeoff between the performance parameters-efficiency, NP oscillations, and waveform quality-The proposed strategy has the ability to settle at the intermediate modulation patterns by transforming into a hybrid modulation signal. Furthermore, considering NP voltage unbalance mitigation as major technical challenge in adjustable modulation strategy, a voltage unbalance compensator that exhibits satisfactory balancing performance for the entire variations of modulation patterns and operating conditions has also been presented. The performance of the proposed modulation strategy in conjunction with voltage unbalance compensator has been evaluated in simulation by widely varying the speed and load of induction motor, and verified in experimentatio

An Improved Modulation Strategy for Fast Capacitor Voltage Balancing of Three-Level NPC Inverters

This paper presents an improved pulsewidth modulation strategy in conjunction with an optimal compensator for fast capacitor voltage balancing in three-level neutral-point-clamped (NPC) inverter. The voltage balancing compensator is designed in such a way that it produces optimal unbalance compensation coefficient according to the inherent limitations related to the variability range of modulating signals. It generates maximum compensating neutral current for the full modulation depth extending into overmodulation region and throughout the entire range of load power factor angles, and thus improves the unbalance compensation ability for all the operating conditions of the inverter. The optimal compensation offset signal corresponding to each operating point is determined from the boundary limit of the auxiliary modulating signals. Particle swarm optimization is applied for such purpose. The performance of the proposed optimal compensator for different combinations of modulation index and load power factors are evaluated through extensive simulation study using Matlab/Simulink and validated in experimentation using a threelevel NPC inverter prototype with induction motor load. Finally, the voltage balancing performances of the proposed compensator are compared with that available in literature to confirm the usefulness of the proposed concept