Showing papers by "Indian Institute of Technology Bhubaneswar published in 2015"

Recent developments in 2D layered inorganic nanomaterials for sensing

Abstract: Two dimensional layered inorganic nanomaterials (2D-LINs) have recently attracted huge interest because of their unique thickness dependent physical and chemical properties and potential technological applications. The properties of these layered materials can be tuned via both physical and chemical processes. Some 2D layered inorganic nanomaterials like MoS2, WS2 and SnS2 have been recently developed and employed in various applications, including new sensors because of their layer-dependent electrical properties. This article presents a comprehensive overview of recent developments in the application of 2D layered inorganic nanomaterials as sensors. Some of the salient features of 2D materials for different sensing applications are discussed, including gas sensing, electrochemical sensing, SERS and biosensing, SERS sensing and photodetection. The working principles of the sensors are also discussed together with examples.

Western Disturbances: A review

Abstract: Cyclonic storms associated with the midlatitude Subtropical Westerly Jet (SWJ), referred to as Western Disturbances (WDs), play a critical role in the meteorology of the Indian subcontinent. WDs embedded in the southward propagating SWJ produce extreme precipitation over northern India and are further enhanced over the Himalayas due to orographic land-atmosphere interactions. During December, January, and February, WD snowfall is the dominant precipitation input to establish and sustain regional snowpack, replenishing regional water resources. Spring melt is the major source of runoff to northern Indian rivers and can be linked to important hydrologic processes from aquifer recharge to flashfloods. Understanding the dynamical structure, evolution-decay, and interaction of WDs with the Himalayas is therefore necessary to improve knowledge which has wide ranging socioeconomic implications beyond short-term disaster response including cold season agricultural activities, management of water resources, and development of vulnerability-adaptive measures. In addition, WD wintertime precipitation provides critical mass input to existing glaciers and modulates the albedo characteristics of the Himalayas and Tibetan Plateau, affecting large-scale circulation and the onset of the succeeding Indian Summer Monsoon. Assessing the impacts of climate variability and change on the Indian subcontinent requires fundamental understanding of the dynamics of WDs. In particular, projected changes in the structure of the SWJ will influence evolution-decay processes of the WDs and impact Himalayan regional water availability. This review synthesizes past research on WDs with a perspective to provide a comprehensive assessment of the state of knowledge to assist both researchers and policymakers, and context for future research.

Abrupt changes in Indian summer monsoon strength during 33,800 to 5500 years B.P.

Abstract: Speleothem proxy records from northeastern (NE) India reflect seasonal changes in Indian summer monsoon strength as well as moisture source and transport paths. We have analyzed a new speleothem record from Mawmluh Cave, Meghalaya, India, in order to better understand these processes. The data show a strong wet phase 33,500–32,500 years B.P. followed by a weak/dry phase from 26,000 to 23,500 years B.P. and a very weak phase from 17,000 to 15,000 years B.P. The record suggests abrupt increase in strength during the Bolling-Allerod and early Holocene periods and pronounced weakening during the Heinrich and Younger Dryas cold events. We infer that these changes in monsoon strength are driven by changes in temperature gradients which drive changes in winds and moisture transport into northeast India.

On the Performance of Graphene-Based D-Shaped Photonic Crystal Fibre Biosensor Using Surface Plasmon Resonance

Abstract: We propose a D-shaped photonic crystal fibre-based surface plasmon resonance sensor considering graphene on silver for sensing of refractive index of analyte and thickness of biolayer. The different structural and material parameters associated with sensor have been optimised. Graphene not only helps in adsorption of biomolecules due to π-π stacking interaction but at the same time prevents oxidation of metal-like silver. Numerical simulation shows that amplitude sensitivity of the proposed structure for chemical analytes is 216 RIU−1 (refractive index unit) with a resolution of 4.6 × 10−5 RIU while the wavelength sensitivity of the proposed sensor is found to be as high as 3700 nm RIU−1 with resolution of 2.7 × 10−5 RIU. Further, the proposed sensor can also be used for the detection of biolayer thickness in both amplitude and wavelength interrogations. An amplitude sensitivity of 0.26 nm−1 with resolution of 39 pm and wavelength sensitivity of 2 nm nm−1 with resolution of 50 pm is achievable for the determination of biolayer thickness. The proposed structure is easy to use as there is no need of filling of voids, and the analytes can be placed easily on the flat surface of photonic crystal fibre (PCF).

Detection and Classification of Power Quality Disturbances Using Sparse Signal Decomposition on Hybrid Dictionaries

Abstract: Several methods have been proposed for detection and classification of power quality (PQ) disturbances using wavelet, Hilbert transform, Gabor transform, Gabor-Wigner transform, S transform, and Hilbert-Haung transform. This paper presents a new method for detection and classification of single and combined PQ disturbances using a sparse signal decomposition (SSD) on overcomplete hybrid dictionary (OHD) matrix. The method first decomposes a PQ signal into detail and approximation signals using the proposed SSD technique with an OHD matrix containing impulse and sinusoidal elementary waveforms. The output detail signal adequately captures morphological features of transients (impulsive and oscillatory) and waveform distortions (harmonics and notching). Whereas the approximation signal contains PQ features of fundamental, flicker, dc-offset, and short- and long-duration variations (sags, swells, and interruptions). Thus, the required PQ features are extracted from the detail and approximation signals. Then, a hierarchical decision-tree algorithm is used for classification of single and combined PQ disturbances. The proposed method is tested using both synthetic and microgrid simulated PQ disturbances. Results demonstrate the accuracy and robustness of the method in detection and classification of single and combined PQ disturbances under noiseless and noisy conditions. The method can be easily expanded for compressed sensing based PQ monitoring networks.

Analysis of critical success factors of humanitarian supply chain: An application of Interpretive Structural Modeling

Abstract: With increasing frequency and intensity of disasters and large number of people being affected by them, the subject needs more attention and a planned approach. And in order to reduce the adverse impact of disasters and to improve the disaster relief practices, academicians and practitioners are emphasizing on a number of diverse factors of humanitarian supply chain by segmenting them into different clusters. This research is intended to address the critical success factors (CSFs) of humanitarian supply chain which emerges during disaster preparedness and immediate response phase. Through a review of literature and expert consultation, 12 critical success factors leading to responsive humanitarian supply chains have been identified. In this paper, the authors have used Interpretive Structural Modeling (ISM) approach to interpret the interdependency among the selected CSFs. In addition, MICMAC (Matrice d'Impacts Croises Multiplication Appliquee a un Classement (cross-impact matrix multiplication applied to classification)) analysis is also used to illustrate the relative driving and dependence power among the selected factors. This paper argues that, Government policies and Organizational structure is the most dominating factor which has the highest driving power and the minimum dependence power as it drive others factors and forms the base of interpretive structure model. The outcome of this research presents the insight of humanitarian supply chain practices and discussion from both a researcher and managerial perspective is also summarized.

Electrodeposition of spinel MnCo₂O₄ nanosheets for supercapacitor applications.

Abstract: Herein, we report a facile, low-cost and one-step electrodeposition approach for the synthesis MnCo2O4 (MCO) nanosheet arrays on indium doped tin oxide (ITO) coated glass substrates. The crystalline phase and morphology of the materials are studied by x-ray diffraction, energy dispersive x-ray analysis and field-emission scanning electron microscopy. The supercapacitor performance of the MCO nanosheets are studied in a three-electrode configuration in 2 M KOH electrolyte. The as-prepared binder-free electrode shows a high specific capacitance of 290 F g−1 at 1 mV s−1 with excellent cyclic stability even after 1000 charge/discharge cycles. The obtained energy density and power density of the MCO nanosheets are 10.04 Wh kg−1 and 5.2 kW kg−1 respectively. The superior electrochemical performances are mainly attributed to its nanosheet like structure which provides a large reaction surface area, and fast ion and electron transfer rate.

On the electric field enhancement and performance of SPR gas sensor based on graphene for visible and near infrared

Abstract: We propose a high performance surface plasmon resonance (SPR) affinity gas sensor based on graphene on Ag in visible and near infrared. Proposed sensor configuration has been optimized for maximum surface plasmon field at the sensing layer interface. The field intensity enhancement factor at sensing layer interface is found to be higher than that of silicon over layer on Ag thereby increasing the imaging sensitivity by 340%, 120% and 82% and detection accuracy by 440%, 150% and 100% as compared to Si on Ag configuration at λ = 653 nm, λ = 850 nm and λ = 1000 nm respectively. The performance of the sensor is found to be high over a broad refractive index range (1.0000–1.0008) of gaseous analyte with sensor resolution of 8 × 10−5 RIU and 2 × 10−5 RIU at λ = 653 nm and λ = 1000 nm respectively. We believe the proposed SPR based gas sensor configuration will open a new route for efficient gas sensing by riding on the advantage of graphene and latest nanofabrication techniques.

Graphene-Based Conducting Metal Oxide Coated D-Shaped Optical Fiber SPR Sensor

Abstract: We report a graphene-based indium tin oxide coated surface plasmon resonance sensor built on a D-shaped optical fiber for near infrared. Different parameters of the proposed sensor have been optimized to obtain a maximal phase matching between the core guided mode and the plasmon mode using finite element method. Wavelength sensitivity of the proposed structure is as high as 5700 nm/RIU with a maximum resolution of $1.754 \times 10^{-5}$ RIU. The proposed sensor can also be used for bio layer thickness monitoring with a maximum resolution of 62.5 pm in wavelength interrogation.

Synthesis, X-ray structure and in vitro cytotoxicity studies of Cu(I/II) complexes of thiosemicarbazone: special emphasis on their interactions with DNA.

Abstract: 4-(p-X-phenyl)thiosemicarbazone of napthaldehyde {where X = Cl (HL1) and X = Br (HL2)}, thiosemicarbazone of quinoline-2-carbaldehyde (HL3) and 4-(p-fluorophenyl)thiosemicarbazone of salicylaldehyde (H2L4) and their copper(I) {[Cu(HL1)(PPh3)2Br]·CH3CN (1) and [Cu(HL2)(PPh3)2Cl]·DMSO (2)} and copper(II) {[(Cu2L32Cl)2(μ-Cl)2]·2H2O (3) and [Cu(L4)(Py)] (4)} complexes are reported herein. The synthesized ligands and their copper complexes were successfully characterized by elemental analysis, cyclic voltammetry, NMR, ESI-MS, IR and UV-Vis spectroscopy. Molecular structures of all the Cu(I) and Cu(II) complexes have been determined by X-ray crystallography. All the complexes (1–4) were tested for their ability to exhibit DNA-binding and -cleavage activity. The complexes effectively interact with CT-DNA possibly by groove binding mode, with binding constants ranging from 104 to 105 M−1. Among the complexes, 3 shows the highest chemical (60%) as well as photo-induced (80%) DNA cleavage activity against pUC19 DNA. Finally, the in vitro antiproliferative activity of all the complexes was assayed against the HeLa cell line. Some of the complexes have proved to be as active as the clinical referred drugs, and the greater potency of 3 may be correlated with its aqueous solubility and the presence of the quinonoidal group in the thiosemicarbazone ligand coordinated to the metal.

High Performance Non‐enzymatic Glucose Sensor Based on One‐Step Electrodeposited Nickel Sulfide

Abstract: Nanostructured NiS thin film was prepared by a one-step electrodeposition method and the structural, morphological characteristics of the as-prepared films were analyzed by X-ray diffractometry (XRD), field emission scanning electron microscopy (FESEM) and energy dispersive X-ray analysis (EDAX). The electrocatalytic activity of NiS thin film towards glucose oxidation was investigated by fabricating a non-enzymatic glucose sensor and the sensor performance was studied by cyclic voltammetry (CV) and amperometry. The fabricated sensor showed excellent sensitivity and low detection limit with values of 7.43 μA μM(-1) cm(-2) and 0.32 μM, respectively, and a response time of <8 s.

Nano-displacement sensor based on photonic crystal fiber modal interferometer

Abstract: A stable nano-displacement sensor based on large mode area photonic crystal fiber (PCF) modal interferometer is presented. The compact setup requires simple splicing of a small piece of PCF with a single mode fiber (SMF). The excitation and recombination of modes is carried out in a single splice. The use of a reflecting target creates an extra cavity that discretizes the interference pattern of the mode interferometer, boosting the displacement resolution to nanometer level. The proposed modal interferometric based displacement sensor is highly stable and shows sensitivity of 32 pm/nm.

Electrodeposited spinel NiCo2O4 nanosheet arrays for glucose sensing application

Abstract: We report the growth of NiCo2O4 nanosheet arrays on a conducting substrate by a simple and highly reproducible electrodeposition method. Non-enzymatic glucose sensing properties of the as-prepared nanosheets are studied. NiCo2O4 nanosheets show a linear response with respect to the change in glucose concentration varying from 5 to 65 μM and exhibit a sensitivity value of 6.69 μA μM−1 cm−2 with a LOD value of 0.38 μM. It is proposed that nanosheets are advantageous for glucose sensing applications because of their large surface area with enormous active edges and superior electrochemical properties providing efficient transport pathways for both electrons and ions.

Oxidative and membrane stress-mediated antibacterial activity of WS2 and rGO-WS2 nanosheets

Abstract: Graphene-based materials have strong cytotoxic attributes against bacteria due to their unique physicochemical properties. We examined the antibacterial activities of nanosheets of the graphene analogue tungsten disulphide (WS2) and a composite of reduced graphene oxide-tungsten disulphide (rGO-WS2), comparing them with reduced graphene oxide (rGO) by a time and concentration dependent viability assay and growth curve studies against four bacterial strains: Gram negative Escherichia coli (E. coli) and Salmonella typhimurium (S. typhimurium), and Gram positive Bacillus subtilis (B. subtilis) and Staphylococcus epidermidis (S. epidermidis). The nanosheets of the rGO-WS2 composite caused a more significant retardation in bacterial growth and inhibitory effect on the tested bacterial strains than WS2, followed by rGO. The tested E. coli and B. subtilis strains were more susceptible than the other strains. A mechanistic study revealed that rGO and WS2 did not produce the superoxide anion (O2˙−) or reactive oxygen species (ROS), but the nanocomposite of rGO-WS2 did produce both. However, all these materials did oxidize glutathione, which serves as a redox state mediator in bacteria. We conclude that the antimicrobial mechanism is due to the combined effect of initial cell deposition on the rGO-WS2 materials, the membrane stress due to direct contact with the nanosheets, and the produced superoxide anion-independent oxidation mechanisms. The beneficial aspects of the physicochemical properties of rGO-WS2, such as its size and conductivity, can be precisely customized to reduce its health and environmental risk factors.

Improved Prediction of Bay of Bengal Tropical Cyclones through Assimilation of Doppler Weather Radar Observations

Abstract: The impact on tropical cyclone (TC) prediction from assimilating Doppler weather radar (DWR) observations obtained from the TC inner core and environment over the Bay of Bengal (BoB) is studied. A set of three operationally relevant numerical experiments were conducted for 24 forecast cases involving 5 unique severe/very severe BoB cyclones: Sidr (2007), Aila (2009), Laila (2010), Jal (2010), and Thane (2011). The first experiment (CNTL) used the NCEP FNL analyses for model initial and boundary conditions. In the second experiment [Global Telecommunication System (GTS)], the GTS observations were assimilated into the model initial condition while the third experiment (DWR) used DWR with GTS observations. Assimilation of the TC environment from DWR improved track prediction by 32%–53% for the 12–72-h forecast over the CNTL run and by 5%–25% over GTS and was consistently skillful. More gains were seen in intensity, track, and structure by assimilating inner-core DWR observations as they provided mor...

Supercapacitors based on patronite–reduced graphene oxide hybrids: experimental and theoretical insights

Abstract: Here we report the hydrothermal synthesis and detailed study on supercapacitor applications of a patronite hybrid, VS4/reduced graphene oxide, which showed an enhanced specific capacitance of ∼877 F g−1 at a current density of 0.5 A g−1. In comparison to bare vanadium sulfide and reduced graphene oxide, the hybrid showed ∼6 times and ∼5 times higher value of specific capacitance, respectively. The obtained energy density (117 W h kg−1) and power density (20.65 kW kg−1) are comparable to those of other reported transition metal sulfides and their graphene hybrids. Theoretical calculations using density functional theory confirm an enhanced quantum capacitance of VS4/graphene composite systems, owing primarily to the shifting of the graphene Dirac cone relative to the band gap of VS4. The results infer that the hybrid has the potential to be used as a high performance supercapacitor electrode.

Atomically thin layers of B-N-C-O with tunable composition.

Abstract: In recent times, atomically thin alloys of boron, nitrogen, and carbon have generated significant excitement as a composition-tunable two-dimensional (2D) material that demonstrates rich physics as well as application potentials. The possibility of tunably incorporating oxygen, a group VI element, into the honeycomb sp 2 -type 2D-BNC lattice is an intriguing idea from both fundamental and applied perspectives. We present the first report on an atomically thin quaternary alloy of boron, nitrogen, carbon, and oxygen (2D-BNCO). Our experiments suggest, and density functional theory (DFT) calculations corroborate, stable configurations of a honeycomb 2D-BNCO lattice. We observe micrometer-scale 2D-BNCO domains within a graphene-rich 2D-BNC matrix, and are able to control the area coverage and relative composition of these domains by varying the oxygen content in the growth setup. Macroscopic samples comprising 2D-BNCO domains in a graphene-rich 2D-BNC matrix show graphene-like gate-modulated electronic transport with mobility exceeding 500 cm 2 V −1 s −1 , and Arrhenius-like activated temperature dependence. Spin-polarized DFT calculations for nanoscale 2D-BNCO patches predict magnetic ground states originating from the B atoms closest to the O atoms and sizable (0.6 eV E g

Strain engineering the work function in monolayer metal dichalcogenides.

Abstract: We use first-principles density functional theory to investigate the effect of both tensile and compressive strain on the work functions of various metal dichalcogenide monolayers. We find that for all six species considered, including MoS2, WS2, SnS2, VS2, MoSe2 and MoTe2, that compressive strain of up to 10% decreases the work function continuously by as much as 1.0 eV. Large enough tensile strain is also found to decrease the work function, although in some cases we observe an increase in the work function for intermediate values of tensile strain. This work function modulation is attributed to a weakening of the chalcogenide-metal bonds and an increase in total energy of each system as a function of strain. Values of strain which bring the metal atoms closer together lead to an increase in electrostatic potential energy, which in turn results in an increase in the vacuum potential level. The net effect on the work function can be explained in terms of the balance between the increases in the vacuum potential levels and Fermi energy.

A porous trimetallic Au@Pd@Ru nanoparticle system: synthesis, characterisation and efficient dye degradation and removal

Abstract: A facile room temperature one-pot synthesis of trimetallic porous Au@Pd@Ru nanoparticles (Au@Pd@RuNPs) has been developed. The trimetallic nanoparticles have been prepared by the successive sacrificial oxidation of cobalt nanoparticles (CoNPs). The average particle size of Au@Pd@RuNPs is 110 nm. The porous nature and the presence of Au, Pd and Ru have been confirmed via TEM, FE-SEM and EDS analyses. The trimetallic nanoparticles have shown excellent catalytic activity towards the reduction of p-nitrophenol and efficient degradation of various azo dyes. This has been further extended towards the removal of colour from waste water via the catalytic degradation of azo dyes. Moreover, the produced amine can be eliminated from the waste water via its sorption on an industrial solid waste dolochar.

Graphene oxide encapsulated gold nanoparticle based stable fibre optic sucrose sensor

Abstract: Optical fibre based localized surface plasmon resonance (LSPR) sensor using graphene oxide (GO) encapsulated Au nanoparticles has been reported for sucrose sensing. Au-nanoparticles (AuNPs) are encapsulated with GO in fixed ratio to prevent the AuNPs from aggregation as agglomeration of AuNPs broadens the absorbance spectra by more than 25%. The TEM results support the formation of 2 nm thickness of GO around Au nanoparticle of approximate size of 30 nm thereby making the sensor stable. The GO encapsulated AuNPs was immobilized on the core of processed and functionalized optical fibre for sucrose sensing. We found that the peak absorbance changes with sucrose refractive index and the sensitivity of 2.288 ΔA/RIU has been obtained i.e. the peak absorbance changes by 75.78% with 0.0395 change in refractive index of sucrose. Our experimental results are in good agreement with theory.

Enhanced field emission of plasma treated multilayer graphene

Abstract: Electron emission properties of multilayer graphene (MLG) prepared by a facile exfoliation technique have been studied. Effect of CO2 Ar, N2, plasma treatment was studied using Raman spectroscopy and investigated for field emission based application. The CO2 plasma treated multilayer graphene shows an enhanced field emission behavior with a low turn on field of 0.18 V/μm and high emission current density of 1.89 mA/cm2 at an applied field of 0.35 V/μm. Further the plasma treated MLG exhibits excellent current stability at a lower and higher emission current value.

Pt-nanoparticle functionalized carbon nano-onions for ultra-high energy supercapacitors and enhanced field emission behaviour

Abstract: In the present work, we have investigated the charge storage capacitive response and field emission behaviour of platinum (Pt) nanoparticles decorated on carbon nano onions (CNOs) and compared them with those of pristine carbon nano onions. The specific capacitance observed for Pt–CNOs is 342.5 F g−1, about six times higher than that of pristine CNOs, at a scan rate of 100 mV s−1. The decoration with Pt nanoparticles, without any binder or polymer separator on the CNO, leading to enhanced supercapacitance is due to easy accessibility of Na2SO4 electrolyte in the active material. The Density Functional Theory (DFT) calculations of these systems reveal enhancement in the Density of States (DOS) near the Fermi energy (EF) on account of platinum decoration on the CNOs. Furthermore, the field emission current density of ∼0.63 mA cm−2 has been achieved from the Pt-CNOs emitter at an applied electric field of ∼4.5 V μm−1 and from the pristine CNOs sample current density of ∼0.4 mA cm−2 has been achieved at an applied electric field of ∼6.6 V μm−1. The observed enhanced field emission behavior has been attributed to the improved electrical conductivity and increased emitting sites of the Pt–CNO emitter. The field emission current stability of the Pt–CNO emitter over a longer duration is found to be good. The observed results imply multifunctional potential of Pt–CNOs, as supercapacitor material in various next generation hybrid energy storage devices, and field emitters for next generation vacuum nano/microelectronic devices.

Effective utilization of a sponge iron industry by-product for phosphate removal from aqueous solution: A statistical and kinetic modelling approach

Abstract: Dolochar, a solid waste generated from sponge iron industry during the process of direct reduction of iron by rotary kiln, is explored as an adsorbent for phosphate removal in this study. The depiction of the adsorption process was done by X-ray diffraction (XRD), Fourier transferred infra-red spectroscopy (FTIR), and Energy dispersive spectroscopy (EDS) analysis. The appearance of phosphorous peak in EDS spectra of spent dolochar confirmed phosphate adsorption. Application of response surface methodology (RSM) and analysis of variance (ANOVA) for modelling and optimization of phosphate removal in batch study and breakthrough time in column study, suggested quadratic models for both the responses. Experimental validation of the optimization process resulted in 98.13% phosphate removal and 24.67 h breakthrough time. Pseudo second order kinetic and Langmuir isotherm illustrated best fit to the experimental data with R2 = 0.98 and R2 = 0.99, respectively. The values of separation factor (1 > RL > 0), Freundlich exponent (n > 1) and thermodynamic parameters (ΔG°, −3442.6 kJ/mol and ΔH°, 6627 kJ/mol) specified favourable spontaneous and endothermic adsorption process. The adsorbent displayed 80% of the original adsorption capacity in the 3rd cycle of reuse. The results of this study support the utility of dolochar as a low cost and highly efficient adsorbent for phosphate removal from aqueous solution.

A Great Escape from the Bay of Bengal ''Super Sapphire-Phailin'' Tropical Cyclone: A Case of Improved Weather Forecast and Societal Response for Disaster Mitigation

Abstract: The very severe cyclonic storm (VSCS) “Phailin (2013)” was the strongest cyclone that hit the eastern coast of the India Odisha state since the supercyclone of 1999. But the same story of casualties was not repeated as that of 1999 where approximately 10 000 fatalities were reported. In the case of Phailin, a record 1 million people were evacuated across 18 000 villages in both the Odisha and Andhra Pradesh states to coastal shelters following the improved operational forecast guidance that benefited from highly skillful and accurate numerical model guidance for the movement, intensity, rainfall, and storm surge. Thus, the property damage and death toll were minimized through the proactive involvement of three-tier disaster management agencies at central, state, and district levels.

Field emission properties of spinel ZnCo2O4 microflowers

Abstract: ZnCo2O4 microflowers were synthesized by a simple low temperature hydrothermal route. A single three-dimensional microflower consists of hundreds of self-assembled petals, with a thickness of several nanometers. These microflowers have exceptionally thin edges with a few petal layers. The ZnCo2O4 microflowers appeared to be stable and good field emitters.