Browsing by Author "Raj Kumar Mishra"

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A review on biomass-derived materials and their applications as corrosion inhibitors, catalysts, food and drug delivery agents
(Elsevier B.V., 2021) Manavi Yadav; Gaurav Goel; Fiona L. Hatton; Madhulika Bhagat; Surinder Kumar Mehta; Raj Kumar Mishra; N. Bhojak
Owing to the overconsumption of petroleum-based resources and growing demand for fossil-based fuels and chemicals, it has become imperative to adopt alternative resources that are renewable. With the availability of biomass, it is believed that this technology has the capability to valorize waste into wealth. Recently, efficient utilization of plant biomass, a chief renewable resource, has gained tremendous attention in research as it offers distinct social, economic, and sustainable benefits. The present review focuses on the various biomass from waste resources. Subsequently, the applications of these polymeric biomass composites are reviewed in catalysis, drug delivery, and food applications. Finally, corrosion studies along with DFT calculations and theoretical aspects have also been reviewed. Naturally occurring carbohydrate polymers found in lignocellulosic biomass are biopolymers have been used for various physical and chemical applications; as catalyst, coatings, drug delivery, corrosion inhibitors etc. This review reports these material applications of carbohydrate polymers. In this review we focus on new and emerging applications of polymers from lignocellulosic biomass. © 2021 The Authors
A Theoretical and Computational Study of Structure-Property Relationship in Five Binary Liquid Alloys
(John Wiley and Sons Inc, 2024) Arvind Singh; Raj Kumar Patel; Raj Kumar Mishra; R. Lalneihpuii
A theoretical model is proposed in this work for the evaluation of composition-dependent thermophysical properties such as the isothermal compressibility, velocity of sound and Debye temperature of liquid binary alloys. Using a square-well (SW) model potential function under mean spherical model approximation, the composition-dependent atomic-level structural functions of Al1-xCux, Ag1-xCux, Au1-xCux, Ag1-xAlx, and Au1-xAgx alloys have been determined and compared with available experimental data. An extensive computation was done to calculate the composition-dependent isothermal compressibility through the structure factor in the long wavelength limit (k→0), and then we employed this data to investigate the velocity of sound in the considered melts. This yields the fundamental maximum frequency with which the constituent particles are vibrating in the melts and is used to determine the composition-dependent Debye temperature, ΘD. The computed Debye temperature of considered melts using the Square-well potential function is found to be in satisfactory agreement with the available DFT and MD simulation results. © 2024 Wiley-VCH GmbH.
Bhatia-Thornton fluctuations, transport and ordering in partially ordered Al-Cu alloys
(Institute of Physics Publishing, 2019) R. Lalneihpuii; Ruchi Shrivastava; C. Lalnuntluanga; Raj Kumar Mishra
The Bhatia-Thornton (BT) correlation functions namely the number-number, concentration-concentration and number-concentration correlation functions in liquid binary melts are important parameters for understanding the complexities in binary liquids. In this paper, the microscopic BT correlation functions of liquid Al-Cu alloys are investigated using square well (SW) potential under mean spherical model approximation. These correlation functions are linearly related to the Ashcroft-Langreth type partial structure factors. Thermodynamically important microscopic function i.e. concentration-concentration correlation function in the long-wavelength limit, S CC(0) is analytically calculated, which is well-known in BT formalism and is often used to characterized the mixing behavior in binary melts. The Warren-Cowley chemical short range order parameters, as function of Cu concentration is also computed in the liquid Al-Cu alloys through structural studies in the long wavelength limit, which gives valuable information regarding ordering in melts. The compound forming behavior in Al-Cu alloys is evidenced by the results obtained for the value of S CC(0) and . Further, transport properties in binary mixture have been determined by using BT-correlation functions and its long wavelength limit values. Kinetic as well as thermodynamic factors were taken care in the computation of dynamic properties of alloys. © 2019 IOP Publishing Ltd and SISSA Medialab srl.
Correlation between structures and atomic transport properties of compound forming liquid Cu-In alloys
(Institute of Physics, 2023) C. Lalnuntluanga; R. Lalneihpuii; Zodinpuia Pachuau; Raj Kumar Mishra
The Lebowitz solution of the Percus-Yevick hard-sphere mixture is invoked with the square-well potential function to determine Ashcroft-Langreth type three partial correlation functions in binary Cu-In liquid alloys. These computed partial correlation functions have been employed to generate Bhatia-Thornton fluctuations in the considered melts. Using these structural parameters we investigate the temperature and composition-dependent diffusion coefficients of considered melts. The computed values of concentration-concentration fluctuations, S C C ( 0 ) in the long-wavelength limit, and the Warren-Cowley short-range order parameter, α ' show the formation of chemical compounds between unlike atoms in the In-rich region of Cu-In melts. We find a very good agreement between theoretically formulated and computed data of S C C ( 0 ) with the corresponding experimental values. Computed results of S C C ( 0 ) and α ' suggest that hetero coordination is favorable over homo coordination in the investigated melts. The validity of the Stokes-Einstein relation was observed over a wide range of temperatures and compositions in the investigated melts. Further, a new correlation between two body pair excess entropy and the Stoke-Einstein relation has been formulated for square-well binary liquid alloys. Surface tension and compressibility as a function of In composition have been computed through microscopic structural functions of the alloys. Computed S C C ( 0 ) , α ' , surface tension and ratio of mutual to intrinsic diffusion (D m /D id ) are found comparable to available simulated data. The computed values of shear viscosity are in good agreement with the experimental data. Calculated results suggest that the combination of hard sphere potential with square-well tail under mean spherical model approximation is one of the good method for determining the structures and transport coefficients of compound forming binary liquid alloys. © 2022 IOP Publishing Ltd.
Evaluation of activation energies and other properties from structural studies of liquid metals and their extension to liquid Ag-In alloy
(2005) R. Venkatesh; Raj Kumar Mishra
Using a hard sphere reference system with square well attractive tail the structure factors are computed for pure metals and then extended to Ag-In binary alloy. The agreement between the theoretical and experimental values is good. Further new equations have been derived for the temperature variation of diffusion coefficients and they are applied successfully to pure metals and extended to the binary Ag-In alloy. The applicability of these equations is verified by evaluating the activation energies and comparing them with literature values for these systems. The chemical short-range order parameter has been computed as a function of composition for Ag-In system through structural studies in the long wave limit, which gives valuable information regarding the nature of the liquid alloy at various compositions. © 2005 Published by Elsevier B.V.
Identification, characterization and expression profiles of Fusarium udum stress-responsive WRKY transcription factors in Cajanus cajan under the influence of NaCl stress and Pseudomonas fluorescens OKC
(Nature Publishing Group, 2019) Gagan Kumar; Raina Bajpai; Ankita Sarkar; Raj Kumar Mishra; Vijai Kumar Gupta; Harikesh B. Singh; Birinchi K. Sarma
The WRKY gene family has never been identified in pigeonpea (Cajanus cajan). Therefore, objective of the present study was to identify the WRKY gene family in pigeonpea and characterize the Fusarium udum stress-responsive WRKY genes under normal, NaCl-stressed and Pseudomonas fluorescens OKC (a plant growth-promoting bacterial strain) treated conditions. The aim was to characterize the Fusarium udum stress-responsive WRKY genes under some commonly occurring field conditions. We identified 97 genes in the WRKY family of pigeonpea, using computational prediction method. The gene family was then classified into three groups through phylogenetic analysis of the homologous genes from the representative plant species. Among the 97 identified WRKY genes 35 were further classified as pathogen stress responsive genes. Functional validation of the 35 WRKY genes was done through generating transcriptional profiles of the genes from root tissues of pigeonpea plants under the influence of P. fluorescens OKC after 24 h of stress application (biotic: Fusarium udum, abiotic: NaCl). The entire experiment was conducted in two pigeonpea cultivars Asha (resistant to F. udum) and Bahar (susceptible to F. udum) and the results were concluded on the basis of transcriptional regulation of the WRKY genes in both the pigeonpea cultivars. The results revealed that among the 35 tentatively identified biotic stress responsive CcWRKY genes, 26 were highly F. udum responsive, 17 were better NaCl responsive compared to F. udum and 11 were dual responsive to both F. udum and NaCl. Application of OKC was able to enhance transcript accumulation of the individual CcWRKY genes to both the stresses when applied individually but not in combined challenge of the two stresses. The results thus indicated that CcWRKY genes play a vital role in the defense signaling against F. udum and some of the F. udum responsive CcWRKYs (at least 11 in pigeonpea) are also responsive to abiotic stresses such as NaCl. Further, plant beneficial microbes such as P. fluorescens OKC also help pegionpea to defend itself against the two stresses (F. udum and NaCl) through enhanced expression of the stress responsive CcWRKY genes when the stresses are applied individually. © 2019, The Author(s).
Influence of atomic-scale structure on the transport, ordering, and thermodynamics of partially ordered Cu-In alloys
(Elsevier B.V., 2022) C. Lalnuntluanga; Ruchi Shrivastava; R. Lalneihpuii; Raj Kumar Mishra
We demonstrate the atomic-level structural properties of liquid Cu-In alloy as a function of In concentration using Square-Well (SW) model potential function under random phase approximation. It was found that the concentration-dependent structure factor S(k) and its Fourier transform, radial distribution function g(r) are in good agreement with the results obtained by the X-ray diffraction technique. Transport coefficients like diffusion coefficient and shear viscosity of liquid Cu-In alloys were estimated through computed structural functions and SW potential function. Interdiffusion coefficients in the melts were computed by solving the well-known Einstein's equation for Brownian particles with SW pair potential under linear trajectory principal. The composition-dependent shear viscosity is calculated using computed diffusion data in modified Stokes-Einstein (SE) relation. Specifically, we demonstrate a breakdown of SE relation at low In concentration in liquid Cu-In alloy. Using model calculations, we investigate the thermodynamic properties of alloy such as enthalpy of mixing, Gibbs free energy of mixing, and entropy of mixing. The concentration-concentration fluctuation at the zero momentum vector SCC(0)shows that there is a strong chemical bond between hetero-atoms in the Cu-rich region of liquid Cu-In alloys. It is worth mentioning here that the computed values of SCC(0), without using any adjusting or experimental parameter are in excellent agreement with experimental values measured by activity data. © 2021 Elsevier B.V.
On the role of structure-dynamic relationship in determining the excess entropy of mixing and chemical ordering in binary square-well liquid alloys
(Institute of Physics Publishing, 2018) R. Lalneihpuii; Ruchi Shrivastava; Raj Kumar Mishra
Using statistical mechanical model with square-well (SW) interatomic potential within the frame work of mean spherical approximation, we determine the composition dependent microscopic correlation functions, interdiffusion coefficients, surface tension and chemical ordering in Ag-Cu melts. Further Dzugutov universal scaling law of normalized diffusion is verified with SW potential in binary mixtures. We find that the excess entropy scaling law is valid for SW binary melts. The partial and total structure factors in the attractive and repulsive regions of the interacting potential are evaluated and then Fourier transformed to get partial and total radial distribution functions. A good agreement between theoretical and experimental values for total structure factor and the reduced radial distribution function are observed, which consolidates our model calculations. The well-known Bhatia-Thornton correlation functions are also computed for Ag-Cu melts. The concentration-concentration correlations in the long wavelength limit in liquid Ag-Cu alloys have been analytically derived through the long wavelength limit of partial correlation functions and apply it to demonstrate the chemical ordering and interdiffusion coefficients in binary liquid alloys. We also investigate the concentration dependent viscosity coefficients and surface tension using the computed diffusion data in these alloys. Our computed results for structure, transport and surface properties of liquid Ag-Cu alloys obtained with square-well interatomic interaction are fully consistent with their corresponding experimental values. © 2018 IOP Publishing Ltd.
Statistical mechanical studies of Al rich Al–Cu melts
(Elsevier B.V., 2020) Raj Kumar Mishra; R. Lalneihpuii; R. Venkatesh
We evaluate the microscopic correlation functions in Al1−xCux melts (x= 0.10, 0.17, 0.25, 0.33 and 0.40) in the attractive and repulsive region of the square well (SW) potential under the mean spherical model (MSM) principle. We derive the temperature and concentration dependent transport coefficients through the computed structural functions and verify the Dzugutov's scaling law in Al1−xCuxliquid alloys. The liquid Al-Cu alloys follow the Stokes–Einstein relation especially in Al-rich melts. The concentration–concentration fluctuations in the long-wavelength limit, i.e. SCC(0) and the Warren–Cowley short-range order parameters, α1 have been computed which explains the compound forming behavior in this melts. SCC(0) is also employed to determine the thermodynamic factor for calculating inter-diffusion coefficients from Darken's approach in liquid alloys. The temperature variation of diffusion coefficients are being applied for the computation of activation energy in liquid Al-Cu alloys by following Arrhenius equation. The theoretically evaluated activation energies of the alloys are in fair agreement with reported values. The composition dependent surface tension is determined and compared with the available experimental results which are in satisfactory agreement. Thus we establish a closer relationship between structure, transport and surface properties in Al1−xCuxmelts without using any adjusting parameters. © 2019
Structural, thermodynamic and other associated properties of partially ordered Ag-In alloy
(2003) R. Venkatesh; Raj Kumar Mishra; R.V. Gopala Rao
Extensive computations have been performed using the Lebowitz solution of hard sphere mixtures as a reference system, and perturbed the hard sphere direct correlation function, Co ij(r), with square well attractive tail. We used mean spherical model to compute the total and partial direct correlation functions in the attractive and repulsive regions of the interacting potential of Ag-In alloy at different compositions. The potential parameters were those obtained for pure metals. With these potential parameters (the partial and total) structure factors were evaluated, and then Fourier transformed to get the partial and total radial distribution functions. Further the well-known Bhatia-Thornton correlation Junctions namely the number-number, concentration-concentration, and number-concentration correlation functions have been computed. We also obtained total and partial coordination numbers from partial and total pair correlation functions respectively. With the help of these pair correlation functions we give the distances between atoms namely Ag-Ag, In-In and Ag-In at different compositions of In in Ag-In alloy. It is found that these distances practically remain constant and are independent of composition, which has been attributed to the formation of segregated clusters of atomic dimensions. Using Kirkwood-Buffs equation, compressibillities have been calculated as a function of composition. The temperature derivative of diffusion coefficient for pure constituents has been formulated and the computed results were compared with the available experimental values. With this model the diffusion coefficients and the friction coefficients of the constituents have been obtained through the use of Helfand's trajectory principle with a reasonable success in the alloy as well. It is found that these metals of the alloy tend to segregate. The ratio of diffusion coefficients of the metals in the alloy is almost a constant and is equal to 0.9. This shows that the alloy forms a regular solution in spite of their tendency to segregate. © 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Temperature effect on structural and transport coefficient of liquid copper under square-well interaction
(American Institute of Physics Inc., 2021) C. Lalnuntluanga; Raj Kumar Mishra
The knowledge of the structure and transfer properties of liquid metals and alloys helps physists, chemists and technologists in their applications for various useful purposes. The structure factor S(k) of liquid Cu was investigated in the temperature range from 1370K to 1873K, using square-well (SW) potential perturbation over hard sphere reference system. Computed S(k) and SW potential were applied to determine the self diffusion of liquid Cu within the available experimental temperature range by using well known Einstein's equation (kBT/ζ). Then the computed results were compared with available experimental results obtained by Quasielastic Neutron Scattering (QNS). Also, the viscosity coefficient, co-ordination number and the coefficient of thermal expansion were computed from the equation of states for square-well fluids within the temperature range for investigation of structure factor. © 2021 Author(s).
Theoretical and computational study on structure, dynamics, and configurational entropy correlation in gold-silicon liquid
(American Institute of Physics, 2025) Raj Kumar Patel; Arvind Kumar R. Singh; R. Lalneihpuii; Raj Kumar Mishra
The structure-property relationship of partially ordered systems poses a different type of open problem for both theoretical and experimental condensed matter researchers. Configurational entropy is an important thermodynamic property that characterizes the glass transition ability of binary liquid alloys. Recently, various experimental and computational approaches have been reported to investigate the configurational entropy in liquids; however, a well-established theoretical definition is still lacking. In this study, the configurational entropy of binary melts has been computed using their pair correlation functions. We determine three partial structure factors that govern the total structure factor S(k) in liquid AuySix alloys at different compositions and temperatures. Fourier inversion of partial and total structure factors gives partial pair correlation functions and radial distribution functions g(r) of AuySix melts, respectively. The computed values of S(k) and g(r) are in excellent agreement with available experimental results. The present model calculation of S(k) for eutectic AuySix melts (x = 19 at. % Si) shows better agreement with the experimental values than the molecular dynamics simulation data. Furthermore, we determine the friction coefficients experienced by constituent particles in the attractive and repulsive regions of the square-well (SW) potential function and employed in Einstein's equation to determine the self- and mutual diffusion coefficients as a function of composition and temperature. The diffusivity of Au and the mutual diffusion coefficient of the alloy are also in good agreement with experimental values compared to molecular dynamics data at its eutectic composition, which confirms the applicability of the SW model for such alloys. © 2025 Author(s).
Theoretical evaluation of structural and various associated properties of Al-Si melts
(2008) Raj Kumar Mishra; R. Venkatesh
Extensive theoretical and computational investigations have been performed using hard sphere mixture with square well attractive tail as a perturbation in binary Al-Si melts. Thus the partial and total radial distribution functions, structure factors and associated derived properties have been calculated and compared with the available experimental values. There is an excellent agreement between theoretical and experimental results. Further, well known Bhatia Thornton correlation functions and in specific the concentration-concentration correlation functions at various compositions of the alloy in the entire momentum space with special emphasis on the values at long wavelength limit have been computed, which are incorporated in the evaluation of the chemical short range order parameter to comprehend the compound formation tendencies in binary melts. The self and mutual diffusion coefficients have been calculated at different atomic percent of Si in Al-Si alloys. The activation energy of pure components is computed from the temperature derivatives of their diffusion coefficients by incorporating the temperature derivative of the correlation functions. © 2008 Elsevier B.V. All rights reserved.
Theoretical Investigation of Structure, Dynamics and Entropy Correlation in Liquid Fe–Al Alloys
(Springer, 2023) Raj Kumar Mishra; C. Lalnuntluanga; Sanjeev Kumar Mishra
Chemical ordering through two microscopic functions namely concentration-concentration fluctuation as k tends to zero, SCC(0 ) and the Warren-Cowley ordering parameter, α′ have been theoretically investigated in Fe–Al melts as function of Al concentration under pair wise square-well (SW) potential function. In view of ordering phenomena in melts, partial and total structure functions, g(r) and self and mutual diffusion coefficients have been theoretically formulated and computed at different compositions of Al in Fe–Al melts. Total structure factor obtained using SW potential function at four compositions of Al are in good agreement with X-ray data obtained by Roik et al. Excess entropy in melts has been determined using computed values of transport coefficients and Dzugutov scaling law. Stokes–Einstein (SE) relation is modified by substituting hydrodynamic radius by nearest neighbor distance in pair correlation function. Validity of the SE relation was examined by comparing theoretically obtained data of viscosity coefficients with experimental values and correlated with excess entropy of the melts obtained through two body approximation. Various physico-chemical properties of industrially important Fe–Al alloys have been reported to establish their correlation with microscopic structure functions. © 2022, The Minerals, Metals & Materials Society and ASM International.
Thermodynamics and mechanism of afatinib-EGFR binding through a QM/MM approach
(Royal Society of Chemistry, 2025) Anjali Kisku; Raghav Wahi; Raj Kumar Mishra
We compute the different thermodynamic interaction parameters between afatinib, a tyrosine kinase inhibitor, and the epidermal growth factor receptor (EGFR) protein found in the cell membrane of lung epidermal cells and primarily responsible for non-small cell lung cancer (NSCLC). We compare the interaction entropy component (−TΔS) of the binding energy obtained through normal mode or Nmode analysis (NMA), interaction entropy (IE), and C2 methods. We observe a much closer value of the binding free energy of the hydrated complex (−19.86 kcal mol−1) with the experimental value (about −13.00 kcal mol−1) compared to those obtained through newly developed IE and C2 methods (about −32.96 kcal mol−1 and −35.47 kcal mol−1, respectively). The present study with molecular mechanics/Poisson-Boltzmann surface area (MM/PBSA) shows the standard deviation of binding energies (σIE = 3.54 kcal mol−1) which is an indication of the convergence of binding entropy with a lower value of energy. Advancement in structural biology with appropriate simulation techniques is an essential feature to meet challenges in covalent drug discovery as such drugs have been used to treat various types of cancers. © 2025 RSC.