Two-Dimensional Siloxene–Graphene Heterostructure-Based High-Performance Supercapacitor for Capturing Regenerative Braking Energy in Electric Vehicles

The development of high-performance electrodes that increase the energy density of supercapacitors (SCs) (without compromising their power density) and have a wide temperature tolerance is crucial for the application of SCs in electric vehicles. Recent research has focused on the preparation of multicomponent materials to form electrodes with enhanced electrochemical properties. Herein, a siloxene–graphene (rGO) heterostructure electrode-based symmetric SC (SSC) is designed that delivers a high energy density (55.79 Wh kg⁻¹) and maximum power density of 15 000 W kg⁻¹. The fabricated siloxene–rGO SSC can operate over a wide temperature range from –15 to 80 °C, which makes them suitable for applications in automobiles. This study shows the practical applicability of siloxene–rGO SSC to drive an electric car as well as to capture the braking energy in a regenerative brake-electric vehicle prototype. This work opens new directions for evaluating the use of siloxene–rGO SSC as suitable energy devices in electric vehicles.     

Modeling and simulation of three phase multilevel inverter for grid connected photovoltaic systems

This paper presents a control for a three phase five-level neutral clamped inverter (NPC) for grid connected PV system. The maximum power point tracking (MPPT) is capable of extracting maximum power from the PV array connected to each DC link voltage level. The MPPT algorithm is solved by fuzzy logic controller. The fuzzy MPPT is integrated with the inverter so that a DC–DC converter is not needed and the output shows accurate and fast response. A digital PI current control algorithm is used to remain the current injected into the grid sinusoidal and to achieve high dynamic performance with low total harmonic distortion (THD). The validity of the system is verified through MATLAB/Simulink and the results are compared with three phase three-level grid connected NPC inverter in terms of THD.     

Structural Stability,Electronic Structure and Mechanical Properties of Li–N–H System

Ab initio calculations are performed to investigate the ground state properties, structural phase transition,electronic structure and mechanical properties of lithium nitride(Li3N), lithium imide(Li2NH) and lithium amide(LiNH2).The computed ground state properties like equilibrium lattice constant, cell volume, valence electron density, cohesive energy, bulk modulus and its derivatives are in good agreement with available experimental data. The structural phase transitions from a-P6/mmm to b-P63/mmc phase at a pressure of 17.5 GPa in Li3N and cubic(Fm3m) to hexagonal(P63/mmc) phase at a pressure of 102 GPa in lithium imide(Li2NH) are observed. A new high pressure hexagonal(P63/mmc)phase is predicted for Li2NH. Electronic structure reveals that Li3N and LiNH2 are semiconductors, whereas Li2 NH is an insulator. The calculated elastic constants indicate that these materials are mechanically stable at ambient condition.     

Electrochemical ways of tapping solar energy: an appraisal

In recent years, solar cell technology has advanced significantly and is nearing commercial viability. Practical solar cells that are capable of converting the solar radiation directly into electricity are now available. It is, however, imperative to couple them with appropriate power storage systems. This article is a brief review of the current status of electrochemical power systems such as storage batteries and fuel-electrolysis cell hybrids which could be successfully utilized to this end. Communication No. 218.     

Growth of delamination cracks due to bending in a [905/05/905] laminate

A study of the growth of delamination due to bending in a [90₅/0₅/90₅] graphite/epoxy laminate is presented. A plane strain finite element analysis is used to determine the strain energy release rate during delamination in a three-point-bend specimen. A closed form expression for energy release rate is obtained from classical lamination theory and Timoshenko beam theory and is compared with the finite element analysis result. These results combined with the experimentally determined critical load, P_crit, are used to calculate the critical strain energy release rate, G_C. The critical energy release rate is also determined experimentally by the compliance method.     

Hepatocyte‐Specific Delivery of siRNAs Conjugated to Novel Non‐nucleosidic Trivalent N‐Acetylgalactosamine Elicits Robust Gene Silencing in Vivo

We recently demonstrated that siRNAs conjugated to triantennary N‐acetylgalactosamine (GalNAc) induce robust RNAi‐mediated gene silencing in the liver, owing to uptake mediated by the asialoglycoprotein receptor (ASGPR). Novel monovalent GalNAc units, based on a non‐nucleosidic linker, were developed to yield simplified trivalent GalNAc‐conjugated oligonucleotides under solid‐phase synthesis conditions. Synthesis of oligonucleotide conjugates using monovalent GalNAc building blocks required fewer synthetic steps compared to the previously optimized triantennary GalNAc construct. The redesigned trivalent GalNAc ligand maintained optimal valency, spatial orientation, and distance between the sugar moieties for proper recognition by ASGPR. siRNA conjugates were synthesized by sequential covalent attachment of the trivalent GalNAc to the 3′‐end of the sense strand and resulted in a conjugate with in vitro and in vivo potency similar to that of the parent trivalent GalNAc conjugate design.     

High-performance platinized carbon electrodes for oxygen reduction in power sources with alkaline electrolytes

A high-performance, oxygen-reducing electrode, made from physically and chemically tailored coconut-shell charcoal substrate catalysed with 7 wt.% platinum, is reported. The electrode can be loaded with current densities of 2000 – 5200 A/m², with negligible deterioration, for periods of up to 1200 h. Extensive electron spectroscopic studies have been conducted to characterise the electroactive species present on the surface of the electrodes during service.     

Oxygen-reducing porous carbon electrode for electrochemical power sources with alkaline electrolytes

The performance of electrodes made from coconut-shell charcoal in alkaline fuel cells and metal/air batteries is reported. The electrode can be loaded     

Influence of the Fuel Used in the Microwave Synthesis of Cr2O3

The synthesis and physico-chemical characterization of chromium oxide (Cr₂O₃) is reported. Samples were prepared by a novel microwave technique using two different fuels, i.e., tetraformaltrisazzine (TFTA) and urea. The physical characterization of the synthesized chromium oxides was achieved using XRD, IR, Raman, BET surface area and pore size distribution (PSD) techniques. The XRD and IR and Raman spectroscopy studies reveal that crystalline Cr₂O₃ is the only phase formed. The XRD, surface area and particle size analysis reveal that the samples prepared using TFTA as the fuel possess a larger surface area, smaller crystalline size, smaller particle size and larger pore diameter. Both samples were calcined at 600°C for 6 h so that they could be used for the catalytic oxidation of LPG. Catalytic runs on the Cr₂O₃ samples revealed that the two samples possess different activity and selectivity. The Cr₂O₃ sample prepared by using TFTA as the fuel gave rise to more dehydrogenation and cracking compared to the sample prepared by using urea as the fuel, which gave more combustion products.