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Advanced material composite of nanocarbons and metal-based materials provides a synergistic effect to obtain excellent electrochemical charge-storage performance and other properties. Herein, 3D porous carbon-metal oxynitride nanocomposites with tunable carbon/metal and oxygen/nitrogen ratio are synthesized uniquely by simultaneous ablation from two different targets by single-step pulsed laser deposition at room temperature. Co ablation of titanium and vanadium nitride targets together with graphite allowed us to synthesize carbon-metal oxynitride porous nanocomposite and exploit them as a binder-free thin film supercapacitor electrode in aqueous electrolyte. We show that the elemental composition ratio and hence the structural properties can be tuned by selecting target configuration and by manipulating the ablation position. We investigate how this tuning capability impacts their charge-storage performances. We anticipate the utilization of as-synthesized various composites in a single PLD production run as next-generation active materials for flexible energy storage and optoelectronic applications., Comment: 18 pages, 7 Figures, 1 table, 4 supplementary figures

In pulsed laser deposition, along conventional deposition on frontside of plasma-plume, target is getting coated on its surface too. For reproducibility, cleaning those residues is the most adopted approach. Herein, we investigate the target-side coated materials and employ them as a binder-free supercapacitor electrode. Ballistic aggregated target-side nanofoam is compact and contains higher sp2-carbon, higher nitrogen content with higher graphitic-N and lower oxygen content with lower COOH group than that of diffusive aggregated conventional nanofoams. They are highly hydrogenated graphite-like amorphous carbon and superhydrophilic. The symmetric microsupercapacitor delivers higher volumetric capacitance of 522 mF/cm3 at 100 mV/s and 104% retention after 10000 charge-discharge cycles over conventional nanofoam (215 mF/cm3 and 85% retention) with the areal capacitance of 134 {\mu}F/cm2 at 120 Hz and ultrafast frequency response. Utilizing those residue materials is of great importance towards sustainable development, zero-waste, and utilization of deposition techniques in full-phase, which is resource-efficient, energy competent and cost-effective., Comment: 22 pages, 5 figures in text, 9 figures in supplementary, 1 table

In a prior study, a novel deterministic compartmental model known as the SEIHRK model was introduced, shedding light on the pivotal role of test kits as an intervention strategy for mitigating epidemics. Particularly in heterogeneous networks, it was empirically demonstrated that strategically distributing a limited number of test kits among nodes with higher degrees substantially diminishes the outbreak size. The network's dynamics were explored under varying values of infection rate. In this research, we expand upon these findings to investigate the influence of migration on infection dynamics within distinct communities of the network. Notably, we observe that nodes equipped with test kits and those without tend to segregate into two separate clusters when coupling strength is low, but beyond a critical threshold coupling coefficient, they coalesce into a unified cluster. Building on this clustering phenomenon, we develop a reduced equation model and rigorously validate its accuracy through comprehensive simulations. We show that this property is observed in both complete and random graphs., Comment: 8 figures, 15 pages including citations

Iron oxide-based nanostructures receive significant attention as an efficient adsorbent for organic dyes removal. The removal properties have strong dependency on the stoichiometry, phases, reactive edges, defect states etc present in the iron-oxides nanostructures. Herein, iron oxide/carbon composite with well-defined heterophased grain boundaries is synthesized by simple precipitation method and followed by calcination. The local structure, spin dynamics and magnetic properties of heterophased iron oxides/carbon composite are thoroughly investigated to explore its cationic and anionic dye removal capability. To validate the effectivity of the presence of heterogeneous grain boundaries, iron oxide/carbon nanocomposite with homogeneous grain boundaries is also examined. It was found that the hetero-phased iron oxide/carbon showed removal capacity of 35.45 mg g-1 and 45.84 mg g-1 for cationic (Crystal Violet) and anionic (Congo Red) dyes, respectively as compared to that of as-synthesised imidazole-capped superparamagnetic {\alpha}-Fe2O3 (25.11 mg g-1 and 40.44 mg g-1, respectively) and homophased iron oxide/carbon nanocomposite (9.41 mg g-1 and 5.43 mg g-1, respectively). The plausible mechanism on the local structural evolution of the heterophase in the course of calcination and increase of the removal capacity is discussed. A detailed dye adsorption investigation is presented including the adsorption kinetic study. The pseudo-second order kinetic model is found to be an appropriate one and suggests that the chemisorption is dominant factor leading to adsorption of dyes. Whereas Weber-Morris model indicate the strong influence of boundary layers of nanocomposite on the adsorption process., Comment: 26 pages, 7 figures, 2 schemes, 4 tables

How higher-order interactions influence the dynamics of second order phase oscillators? We address this question using three coupled Kuramoto phase oscillators with inertia under both pairwise and higher order interactions, finding collective states, which are absent for pair-wise interactions. Chimera states appear in an expanded parameter region of the 3-node network by comparison to the network's response in the absence of the higher-order interactions. %That attempt enables us to understand the emergence of chimera states. This small network of three nodes is investigated for different sets of phase lags and over a range of negative to positive coupling strength of pairwise as well as higher order or group interactions. It demonstrates how important are the choices of the phase lag and the sign of the coupling for the emergent dynamics of the system., Comment: 7 pages, 5 figures

Manipulation of long-range order in two-dimensional (2D) van der Waals (vdW) magnetic materials (e.g., CrI$_3$, CrSiTe$_3$ etc.), exfoliated in few-atomic layer, can be achieved via application of electric field, mechanical-constraint, interface engineering, or even by chemical substitution/doping. Usually, active surface oxidation due to the exposure in the ambient condition and hydrolysis in the presence of water/moisture causes degradation in magnetic nanosheets which, in turn, affects the nanoelectronic/spintronic device performance. Counterintuitively, our current study reveals that exposure to the air at ambient atmosphere results in advent of a stable nonlayered secondary ferromagnetic phase in the form of Cr$_2$Te$_3$ (T$_{C2}$ ~ 160 K) in the parent vdW magnetic semiconductor Cr$_2$Ge$_2$Te$_6$ (T$_{C1}$ ~ 69 K). In addition, the magnetic anisotropy energy (MAE) enhances in the hybrid by an order from the weakly anisotropic pristine Cr$_2$Ge$_2$Te$_6$ crystal, increasing the stability of the FM ground state with time. Comparing with the freshly prepared Cr$_2$Ge$_2$Te$_6$, the coexistence of the two ferromagnetic phases in the time elapsed bulk crystal is confirmed through systematic investigation of crystal structure along with detailed dc/ac magnetic susceptibility, specific heat, and magnetotransport measurement. To capture the concurrence of the two ferromagnetic phases in a single material, Ginzburg-Landau theory with two independent order parameters (as magnetization) with a coupling term can be introduced. In contrast to rather common poor environmental stability of the vdW magnets, our results open possibilities of finding air-stable novel materials having multiple magnetic phases.

The role of topological heterogeneity in the origin of extreme events in a network is investigated here. The dynamics of the oscillators associated with the nodes are assumed to be identical and influenced by mean-field repulsive interactions. An interplay of topological heterogeneity and the repulsive interaction between the dynamical units of the network triggers extreme events in the nodes when each node succumbs to such events for discretely different ranges of repulsive coupling. A high degree node is vulnerable to weaker repulsive interactions, while a low degree node is susceptible to stronger interactions. As a result, the formation of extreme events changes position with increasing strength of repulsive interaction from high to low degree nodes. Extreme events at any node are identified with the appearance of occasional large-amplitude events (amplitude of the temporal dynamics) that are larger than a threshold height and rare in occurrence, which we confirm by estimating the probability distribution of all events. Extreme events appear at any oscillator near the boundary of transition from rotation to libration at a critical value of the repulsive coupling strength. To explore the phenomenon, a paradigmatic second-order phase model is used to represent the dynamics of the oscillator associated with each node. We make an annealed network approximation to reduce our original model and thereby confirm the dual role of the repulsive interaction and the degree of a node in the origin of extreme events in any oscillator., Comment: 10 pages, 5 figures, Accepted for publication in Chaos: An Interdisciplinary Journal of Nonlinear Science

Developing methods to analyse infection spread is an important step in the study of pandemic and containing them. The principal mode for geographical spreading of pandemics is the movement of population across regions. We are interested in identifying regions (cities, states, or countries) which are influential in aggressively spreading the disease to neighboring regions. We consider a meta-population network with SIR (Susceptible-Infected-Recovered) dynamics and develop graph signal-based metrics to identify influential regions. Specifically, a local variation and a temporal local variation metric is proposed. Simulations indicate usefulness of the local variation metrics over the global graph-based processing such as filtering., Comment: 5 pages, 4 figures, submitted to ICASSP 2023

Under mechanical abuse conditions, the failure of lithium-ion batteries occurs in various stages characterized by different force, temperature and voltage response which require it's in-situ measurements for analysis. Firstly, four sizes of commercially available lithium-iron phosphate batteries (LFPB) viz. 18650, 22650, 26650, and 32650 are subjected to quasi static lateral, longitudinal compression, and nail penetration tests. The failure, characterized by the voltage drop and temperature rise, at the onset of the first internal short-circuit (ISC), is identified by Aurdino-based voltage sensor module and temperature measurement module, respectively. The battery failure load and peak temperature at the onset of ISC are found to rely on the battery size strongly. The failure is observed to be delayed for small-sized 18650 batteries during lateral compression, unlike longitudinal compression and nail penetration test. At the onset of the short circuit, the temperature rise above the ambient value is different for different LFPBs. It is found to be maximum (64.4 degree C ) for LFPB 32650 under longitudinal compression and minimum (29.5 degree C) under lateral compression tests amongst the considered geometries. Further, LFPB 26650 exhibited a balanced thermal behavior during the considered abused condition. Such data can be sensed timely for effective thermal management and improved safety of lithium-ion batteries., Comment: 15 pages, 6 Figures, 2 table

We have investigated the effect of nitrogen (N2) as a carrier gas on the growth of vertical graphene nanosheets (VGN) by plasma enhanced chemical vapor deposition (PECVD). It is demonstrated that addition of nitrogen gas with a hydrocarbon precursor can enhance the nucleation and growth rate of graphitic base layer as well as vertical sheets. The gas also simultaneously acts as an etchant and a dopant element. The density of vertical sheets increases up to certain limit and start to decrease with further increase in N2 concentration. The synthesized VGN exhibit sheet resistance from 0.89 to 1.89 K{\Omega}/sq. and mobility from 8.05 to 20.14 cm2/V-s, depending on the morphology and type of carrier concentration. These results reveal that the surface morphology and electronic properties of VGN can be tuned by incorporation of nitrogen gas during the growth phase., Comment: 10 pages, 5 figures, 4 tables

Vertical Graphene Nano sheets (VGN) have become promising candidates for a wide range of applications due to their unique architecture and remarkable properties. However, utilization of VGN in potential applications relies on their structural and thermal stability in ambient conditions. The present study investigates the environmental aging effects and thermal stability of VGN. The effects of aging on VGN are investigated by Raman spectroscopy, X-ray Photoelectron spectroscopy and electrical measurements at regular intervals for a period of six months. Thermogravimetry was employed to examine the thermal stability of VGN and it is found that they are highly stable upto 575 C in ambient atmosphere. Detailed spectroscopic analysis substantiated the retention of structural quality and surface chemistry of VGN over the test period. These findings asserted the long-term structural as well as thermal stability of VGN up to 575 C and validate their potential utilization for the next-generation device applications., Comment: 10 pages, 6 Figures

Aqueous asymmetric electrochemical capacitor, with their high power density and superior cycle stability in comparison to conventional batteries, are presently considered as the most promising contender for energy storage. However, fabricating an electrode material and choosing a suitable aqueous electrolyte are vital in developing an electrochemical capacitor device with high charge storage capacity. Herein, we report a feasible method to synthesize MnO2/Vertical graphene nanosheets (VGN) and Fe2O3/VGN as positive and negative electrodes, respectively. The surface of VGN skeleton is independently decorated with MnO2 having sponge gourd-like morphology and Fe2O3 having nanorice like morphology. A schematic representation of the growth mechanism for metal oxide on VGN network is established. Both the electrode have shown around 250 times higher charge-storage capacity than the bare VGN (0.47 mF/cm2) with the specific capacitance of 118 (MnO2/VGN) and 151 mF/cm2 (Fe2O3/VGN). In addition to the double layer capacitance contribution, the porous interconnected vertical graphene architecture serves as a mechanical backbone for the metal oxide materials and provides multiple conducting channels for the electron transport. The fabricated asymmetric device exhibited a specific capacitance of 76 mF/cm2 and energy density of 71 microWh/cm2 with an excellent electrochemical stability up to 12000 cycles, over a potential window of 2.6 V. The commendable performance of asymmetric electrochemical capacitor device authenticated its potential utilization for next-generation portable energy storage device., Comment: 18 pages, 7 figures, 1 tables

Graphene is well known to grow as flat sheets aligned with the growth substrate. Oriented graphene structures typically normal to the substrate have recently gained major attention. Most often, normal orientation is achieved in plasma-assisted growth and is believed to be due to plasma induced in-built electric field, which is usually oriented normal to the substrate. This work focuses on the effect of in-built electric field on growth direction, morphology, interconnectedness, and physical properties of various configurations of graphene structures and reveals the unique dependence of these features on electric field orientation. It is shown that tilting of growth substrates from parallel to normal direction with respect to the direction of inbuilt plasma electric field leads to the morphological transitions from flat graphene structure, to oriented individual graphene sheets and then interconnected three-dimensional networks of oriented graphene sheets. The revealed transition of the growth orientation leads to change in wetting nature, types of defect in graphitic structures as well as affects their charge storage capacity when used as supercapacitor electrodes. This simple and versatile approach opens new opportunities for the production of potentially large batches of differently oriented and structured graphene sheets in one production run., Comment: 12 pages, 4 Figures

The plasma deposition wall coated composite of ZnO and {\alpha}-Fe2O3 (ZF-W) after exposure to ~ 2000 {\deg}C, mostly considered as waste-materials and cleaned out from the deposition unit, was subjected to anneal at 300, 500 and 1000 {\deg}C to manipulate the structural properties. An evolution of defect states along with the structural changes has been identified as annealing temperature was varied. As a consequence, an unstable state of ZnFe2O4 was found to be stabilized at 500 {\deg}C and migration of Zn from ZnO causes the phase transformation from the {\alpha}-Fe2O3 to ZnFe2O4. While implemented for methyl blue adsorption/degradation without the effect of any external sources, the degradation for ZF-W annealed at 300 {\deg}C, 500 {\deg}C and 1000 {\deg}C were 84%, 68% and 82%, respectively. Compared to annealed structures, pristine ZF-W delivered the highest methyl blue adsorption efficiency of 86%. The changes in adsorption/degradation properties have been correlated with the simultaneous evolution of defects and structural properties of ZF-W as annealed at different temperatures. The plausible mechanism on the interaction of methyl blue with the composites on the adsorption/degradation is proposed. These findings give a clear indication on the importance of defects presence in the mixed metal oxide composite to obtain high-performance degradation/adsorption properties for sustainable wastewater treatment., Comment: 20 pages, 6 Figures

As renewable energy is becoming a critical energy source to meet the global demand, electrochemical energy storage devices become indispensable for the efficient energy storage and reliable supply. The electrode material is the key factor determining the energy storage capacity and the power delivery of the devices. Carbon-based materials are emerging as a viable candidate for electrodes, yet their low energy densities impede the development of advanced energy storage materials. Nanoparticle decoration of the carbon structures is one of the most promising and easy-to-implement a strategy to enhance the charge-storage performance of carbon-based electrodes. Decoration by nanoparticles of metals, metal oxides, nitrides, carbides, phosphides, chalcogenides, and bimetallic components lead to significant enhancements in the structural and electronic properties, pore refinement, charge storage, and charge transfer kinetics of both pristine and doped carbon structures, thereby making their performance promising for next-generation energy storage devices. This review covers the state-of-art nanoparticle decorated nanocarbons for battery, supercapacitor, and metal-ion capacitor applications. A critical analysis of the elemental composition, structure, associated physico-chemical properties and performance relationships of nanoparticle-decorated nanocarbon electrodes is provided as well to inform the future development of the next generation of advanced energy storage materials, devices, and systems., Comment: 67 pages, 17 figures, 5 tables

Symmetries in a network connectivity regulate how the graph's functioning organizes into clustered states. Classical methods for tracing the symmetry group of a network require very high computational costs, and therefore they are of hard, or even impossible, execution for large sized graphs. We here unveil that there is a direct connection between the elements of the eigen-vector centrality and the clusters of a network. This gives a fresh framework for cluster analysis in undirected and connected graphs, whose computational cost is linear in $N$. We show that the cluster identification is in perfect agreement with symmetry based analyses, and it allows predicting the sequence of synchronized clusters which form before the eventual occurrence of global synchronization., Comment: 5 pages, 3 figures (Communicated to Physical Review Letters)