Browsing by Author "Neeraj Mehta"

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3D nanocomposites of β-TCP-H3BO3-Cu with improved mechanical and biological performances for bone regeneration applications
(Nature Research, 2025) Sarvesh Kumar Avinashi; Rajat Kumar Mishra; n. Shweta; Saurabh Kumar; Amreen Shamsad; Shama Parveen; Surajita Sahu; Savita Kumari; Zaireen Fatima; Sachin Kumar Yadav; Monisha Banerjee; Monalisa Mishra; Neeraj Mehta; Chandkiram Gautam
Recently, 3-D porous architecture of the composites play a key role in cell proliferation, bone regeneration, and anticancer activities. The osteoinductive and osteoconductive properties of β-TCP allow for the complete repair of numerous bone defects. Herein, β-TCP was synthesized by wet chemical precipitation route, and their 3-D porous composites with H3BO3 and Cu nanoparticles were prepared by the solid-state reaction method with improved mechanical and biological performances. Several characterization techniques have been used to investigate the various characteristics of fabricated porous composites. SEM and TEM studies revealed the porous morphology and hexagonal sheets of the β-TCP for the composite THC8 (82TCP-10H3BO3-8Cu). Moreover, the mechanical study showed excellent compressive strength (188 MPa), a high Young’s modulus (2.84 GPa), and elevated fracture toughness (9.11 MPa.m1/2). An in vitro study by MTT assay on osteoblast (MG-63) cells demonstrated no or minimal cytotoxicity at the higher concentration, 100 µg/ml after 24 h and it was found a more pronounced result at 20 µg/ml on increasing the concentration of Cu nanoparticles after incubating 72 h. The THC12 composite showed the highest antibacterial potency exclusively against B. subtilis. S. pyogene, S. typhi and E. coli. at 10 mg/ml, indicating its potential effectiveness in inhibiting all of these pathogens. Genotoxicity and cytotoxicity tests were also performed on rearing Drosophila melanogaster, and these findings did not detect any trypan blue-positive staining, which further recommended that the existence of composites did not harm the larval gut. Therefore, the fabricated porous composites THC8 and THC12 are suitable for bone regrowth without harming the surrounding cells and protect against bacterial infections. © The Author(s) 2025.
A comprehensive iso-conversional analysis of recrystallization in Se78-xTe20Sn2Mx (x = 0, 2; M = In, Ge, Sb, and Pb) alloys
(Elsevier B.V., 2025) Kaushal Kumar Sarswat; A. Dahshan; Neeraj Mehta
The model-fitting non-isothermal methodologies provide valuable insights into the recrystallization, delineating the comprehensive activation energy involved. Investigating the kinetics parameter of recrystallization using their dependence on the conversion reveals meticulous aspects of the recrystallization that cannot be achieved using the non-isothermal model fitting methods. With this perspective in mind, our investigation delves into the iso-conversional analysis of the recrystallization in Se78-xTe20Sn2Mx (x = 0, 2; M = In, Ge, Sb, and Pb). In the present article, we have examined the dependence of iso-conversional activation energy Ec, recrystallization rate constant energy Kc, and order parameter n as a function of the temperature and the degree of conversion αc. Furthermore, we have observed the validity of the Meyer-Neldel compensation rule in the iso-conversional recrystallization. The effect of In, Ge, Sb, and Pb on the iso-conversional kinetic parameters (Ec, Kc, and n) has been analyzed by measuring their percentage change before and after the recrystallization. © 2024 Elsevier B.V.
A comprehensive study of radiation shielding parameters of chalcogens-rich quaternary alloys for nuclear waste management
(Elsevier B.V., 2024) Kaushal Sarswat; Shiv Kumar Pal; Z.Y. Khattari; A. Dahshan; Neeraj Mehta
The current study examines the impact of metal additives on the shielding characteristics of Se76Te20Sn2M2 (where M = Ge, In, Sb, and Pb). These glasses are useful as shielding materials against high-energy radiation, such as X-rays and ϒ-rays, because these glasses have better values of shielding parameters compared to other potential candidates in the race for nuclear safety applications. To this end, we have calculated various radiation-related protection parameters using an online application called Phy-X/PSD. Using this program, we have estimated a complete list of radiation shielding parameters. The impact of the fourth element M (M = Ge, In, Sb, and Pb) on these parameters is also discussed. The maximum mass attenuation coefficient (MAC) was recorded at a photon energy of 15 keV for the incorporation of lead. Half-value layer (HVL) values peaked at 6 MeV and it attained its maximum value for germanium. The highest and lowest values of the linear attenuation coefficients (LAC) were obtained for Se76Te20Sn2Pb2 and Se76Te20Sn2Ge2 alloys respectively. Notably, the Se76Te20Sn2Pb2 alloy exhibited the highest values of effective atomic number (Zeff), electron density (Neff), atomic cross-section (ACS), and electronic cross-section (ECS), indicating superior shielding performance. Conversely, energy absorption buildup factors (EABF) and exposure buildup factors (EBF) were highest for Se76Te20Sn2Ge2 alloy. Neutron attenuation was most effective in the Se76Te20Sn2In2 and Se76Te20Sn2Pb2 compositions. Overall, the incorporation of lead in the parent glass demonstrated superior shielding capability compared to the other compositions studied. © 2024 Elsevier B.V.
A thermodynamic approach to indium-enriched Se-Te-Sn alloy systems
(Elsevier B.V., 2025) Kaushal Kumar Sarswat; Neeraj Mehta
Differential scanning calorimetry (DSC) has been used to study phase transformations of glassy-ceramic sample Se78-xTe20Sn2Inx (x = 0, 2, 4, 6) alloys under nonisothermal conditions and determine various thermodynamic parameters. The effect of the Indium additive in Se–Te–Sn glasses has been observed through specific heat (ΔCp) measurements. The value of ΔCp is maximum and minimum for Se72Te20Sn2In6 and Se78Te20Sn2, i.e. 0.0249 and 0.006 kJ/kg֩C. These measurements have also been used to assess several thermodynamic quantities as a function of temperature, including the Gibbs free energy difference (ΔG), entropy difference (ΔS), and enthalpy difference (ΔH) between the undercooled melt and the corresponding equilibrium solid phases. The values of ΔSgc, ΔHgc, and ΔGgc are maximum for Se72Te20Sn2In6, i.e. 0.297, 12.3, and −3.3 J/g֩C respectively, and minimum for Se78Te20Sn2, i.e. 0.063, 3.6, and −0.28 J/g֩C respectively. The values of Cp after glass transition (Cpe) and below glass transition temperature (Cpg) have also been discovered to be strongly composition-dependent. We observed two new correlations: one reveals the linear variation in the logarithm of the change in specific heat (ΔCp) with the logarithm of the heating rate (i.e., log i), and the other shows the linear variation between the Δ(dα/dT) and the logarithm of the heating rate (i.e., log β). The S, G, Cp, and H curves obey the realistic physical relations that are thermodynamically consistent for a second-order phase transition, as defined by Ehrenfest. The Gibbs energy function, on the other hand, has an inflexion point at the transition temperature. © 2025 The Authors
An introduction to x-ray photoelectron spectroscopy
(Nova Science Publishers, Inc., 2023) Neeraj Mehta
X-ray photoelectron spectroscopy (XPS) is a quantitative technique for the measurement of the elemental composition of the exterior of a substance. The XPS technique also sheds light on the binding states of the elements of a specimen under observation. Since this technique has exceptional sensitivity to the valence states of elements, therefore, it plays the role of a probe to describe the structural modifications of the molecules and the chemical shift due to their interaction between them and the metal centers. XPS is now a conventional approach for the routine investigation of a large number of substances (e.g., inorganic/organic alloys and compounds, metallic/non-metallic substances, catalysts, non-crystalline solids, polymers, etc). This chapter covers the historical perspective of the XPS technique and its overview. The future aspects of X-ray photoelectron spectroscopy have also been discussed. © 2023 Nova Science Publishers, Inc. All rights reserved.
Analysis of high-energy radiation shielding features of SeTeSn glass after incorporation of bismuth
(Elsevier Ltd, 2024) Vishnu Saraswat; Z.Y. Khattari; Neeraj Mehta
The main goal of this study is to evaluate how well several quaternary Chalcogenide Glasses (ChGs) shield against extremely intense radiation, such as X-rays and gamma rays. The ChGs under investigation are part of the quaternary glass system SeTeSnBi. By using the Phy-X/PSD program, it was possible to determine some important safety factors. We were specifically able to compute the linear/mass attenuation coefficients thanks to this software. Interestingly, we discover that these values are higher than those of several traditional and commercially available glasses, suggesting better-shielding characteristics. In addition, we investigated numerous important shielding characteristics, such as the removal cross-section, mean free path, transmission factor, half-value layer, and radiation protection efficacy. Furthermore, estimates have been made for the mechanical properties, such as the bulk modulus, shear modulus, longitudinal modulus, and Poisson's ratio. Examining the effects of substituting Bismuth atoms for Selenium atoms on the shielding capabilities of the original SeTeSn glass was a crucial component of our study. These thorough examinations offer insightful information on the possible uses of these quaternary ChGs as cutting-edge radiation shielding materials. © 2024 Elsevier Ltd
Analysis of physicochemical properties in covalent network chalcogenide glasses (ChGs): critical review of theoretical modeling of chemical bond approach
(Springer Nature, 2019) Namrata Chandel; Neeraj Mehta
The Group 16 elements are frequently named as chalcogens (‘ore builders’). From the geographical point of view, they are known as chalcophiles which are the soft elements (keeping in mind the terminology of the hard/soft acids and bases concept). In the geographical sense, chalcophiles preferably form minerals with sulfur (S), selenium (Se) and tellurium (Te). However, oxygen (O) tends to bind preferably to lithophiles, which are hard elements such as the alkali metals, early transition metals, and silicon. The special position of oxygen amongst the chalcogen elements is its association with its very high electronegativity, which in turn correlates with its high ionization energy and the small atomic radius; which makes it difficult for oxygen to act as a central atom in electron-rich multicentre bonds. In the present script, we have reviewed the models for theoretical prediction of some significant physical parameters i.e. coordination number, constraints, density, molar volume, cohesive energy and heat of atomization etc. for the three generations of Se rich multi-component glasses are presented. The present theoretical study of the multi-component chalcogenide glasses reveals that there is a significant change in the structural environment of the three generations (binary, ternary and quaternary systems) due to rigidity percolation. © 2019, Springer Nature Switzerland AG.
Analysis of shielding effectiveness of quaternary SeTeSnSb glasses
(Elsevier Ltd, 2025) Shiv Kumar Pal; Z. Y. Khattari; A. Dahshan; Neeraj Mehta
In this endeavour, we have reported the effect of antimony as a chemical modifier in parent STS glassy systems in studying its radiation shielding capabilities. Using a renowned melt-quench method, we have synthesized a glassy Se78-xTe20Sn2Sbx (0 ≤ x ≤ 6) system. Compared to other prospective candidates in the race for nuclear safety applications, these glasses have greater shielding characteristics, making them effective as shielding materials against high-energy radiation, such as X-rays and ϒ-rays. To achieve this, we used an online program called Phy-X/PSD to compute radiation-related protection parameters. We have estimated an exhaustive list of radiation shielding parameters using this application. The impact of the antimony on these parameters is also discussed. © 2025 Elsevier Ltd
Applicability of Augis-Bennett relation for determination of activation energy of glass transition in some Se rich chalcogenide glasses
(Elsevier Editora Ltda, 2016) Shipra Saraswat; Neeraj Mehta; Surendra Dutt Sharma
The present work reports the results of non-isothermal DSC measurements on some Se-based ternary glasses for evaluation of activation of glass transition. The activation energy of glass transition (Eg) is determined using Augis-Bennett's relation, which is basically derived for amorphous to crystalline phase transition. Moynihan's relation which is derived on the concept of thermal relaxation and is basically used for glass transition is also used for determination of Eg values. We have observed that Eg values obtained from Augis-Bennett's relation are in admirable agreement with the Eg values which are obtained using Moynihan's relation. © 2015 Brazilian Metallurgical, Materials and Mining Association.
Applications of x-ray photoelectron spectroscopy in the field of art and archaeology
(Nova Science Publishers, Inc., 2023) Neeraj Mehta
For the inspection of materials belonging to the cultural heritage, X-ray photoelectron spectroscopy (XPS) is found very helpful in the arena of art and archaeology. The archaeological or artistic objects consisting of metallic substances generally possess the conducting behavior and therefore XPS is a prime technique for the inspection of their chemical compositions. Because of the capability of identifying the chemical state and excellent surface sensitivity, XPS has become the favourite choice amongst the researcher working on the analysis of cultural heritage substances that belong to art and archaeology. The principal aim of this chapter is to highlight the applications of XPS in the investigation of archeological and artistic substances. © 2023 Nova Science Publishers, Inc. All rights reserved.
Assessment of gamma and neutron shielding features of Se80-yTe20My (M = Fe, Co, Ni, Cu, y = 0 and 2) alloys for radiation safety applications
(2025) Nisha Kumari; Vishnu Saraswat; Shiv Kumar Pal; Ishu Sharma; Z. Y. Khattari; Neeraj Mehta
[No abstract available]
Beyond graphene basics: A holistic review of electronic structure, synthesis strategies, properties, and graphene-based electrode materials for supercapacitor applications
(Elsevier Ltd, 2025) Sachin Kumar Yadav; A. Sameer Ruban Kumar; Neeraj Mehta
This review presents a comprehensive analysis of graphene-based electrode materials for supercapacitor application, focusing on electronic structure, synthesis strategies, and key attributes. The remarkable 2D-structure of graphene, characterized by sp2 hybridized carbon atoms, confers exceptional electronic mobility (100000 cm2V−1s−1), large specific surface area (2600 m2g-1), and mechanical flexibility (2.4 ± 0.4 TPa), making it an ideal contender for next-generation energy storage devices. We have discussed various synthesis strategies, including CVD, mechanical exfoliation, and chemical reduction, emphasizing their impact on the electrochemical performance of graphene electrodes. The integration of graphene with other nanomaterials, such as metal oxides, TMDs, conducting polymers, and MXenes, is explored to enhance the specific capacitance, cycle stability, and energy density of supercapacitor electrode materials. This review also covers the tunable electronic properties of graphene, addressing charge transport, ion diffusion, and electrochemical performance, which are critical for efficient supercapacitor design. Graphene-based electrodes' flexibility and mechanical stability are examined, highlighting their role in wearable and portable electronic applications. Challenges such as large-scale production, electrode degradation, and cost-effectiveness are also discussed, offering potential solutions through innovative synthesis routes and composite material design. This review provides a holistic perspective on the current advancement of graphene-based electrode materials for supercapacitor applications. © 2025 Elsevier Ltd
Calorimetric studies of crystallisation kinetics of Se75Te15-xCd10Inx multi-component chalcogenide glasses using non-isothermal DSC
(2010) Sunil Kumar; Kedar Singh; Neeraj Mehta
The crystallisation kinetics of bulk Se75Te15-xCd10Inx (x = 0, 5, 10 and 15) multi-component chalcogenide glasses have been studied using differential scanning calorimetry with different heating rates (5, 10, 15 and 20 K/min) under non-isothermal conditions. Various kinetic parameters of crystallisation, such as the onset crystallisation temperature, peak crystallisation temperature, activation energy for crystallisation and order parameter have been determined. The composition dependence of these parameters is explained in terms of topological models based on constraint theory. © 2010 Taylor and Francis.
Calorimetric studies of crystallization for multi-component glasses of Se–Te–Sn–Ag (STSA) system using model-free and model-fitting non-isothermal methods
(Springer Netherlands, 2017) Ankita Srivastava; Namrata Chandel; Neeraj Mehta
Silver-containing chalcogenide glasses are well-known candidates for technical applications as well as for the fundamental studies. In the present report, we have studied the kinetics of glass/crystal phase transformation in novel synthesized glasses of STSA system. For this, purpose, differential scanning calorimetric technique has been employed at four different heating rates (5, 10, 15, 20 K min−1). This paper explores the thermal analysis of calorimetric data using both advanced iso-conversional methods for the determination of effective activation energy as a function of extent of crystallization and classical non-isothermal methods for the determination of over-all crystallization activation energy. Iso-conversional methods, such as Kissinger–Akahira–Sunose method and Flynn–Wall–Ozawa method, have been used to study the variation of activation energy of crystallization and other kinetic parameters with extent of crystallization. Non-isothermal methods (Kissinger method, Augis–Bennett method, and Matusita–Sakka method) have been used to determine over-all activation energy of crystallization and other significant parameter of thermally activated crystallization. We have also explained the composition dependence of various kinetic parameters. © 2016, Akadémiai Kiadó, Budapest, Hungary.
Calorimetric studies of crystallization in Se76Te20Sn2Ge2 glass under heating/cooling mode
(Institute of Physics, 2023) Shiv Kumar Pal; Dipti Sharma; Neeraj Mehta
In the liquid-solid phase transition analysis, it was observed that two phenomena namely crystallization and glass transition take place, whenever we cool a liquid or melt a solid. In the present endeavor, we have tried to analyze the comparative study of crystallization kinetics using comprehensive iso-conversional methods in both heating/cooling modes of quaternary Se76Te20Sn2Ge2 glassy material synthesized by a very simple and famous melt quenching technique. Differential Scanning Calorimetry (DSC) was employed for this analysis. The effect of heating, as well as cooling rates on the crystallization kinetics, was investigated. Various kinetic parameters like activation energy using the iso-conversional approach, the reaction rate constant, the Avrami index, Meyer-Neldel energy, etc have been calculated for both heating and cooling modes. © 2022 IOP Publishing Ltd.
Calorimetric studies of the glass transition phenomenon in glassy Se 75Te15-xCd10Inx alloys using the non-isothermal DSC technique
(2010) Sunil Kumar; Kedar Singh; Neeraj Mehta
Glass transition kinetics was studied in a glassy Se75Te 15-xCd10Inx (x = 0, 5, 10 and 15) system. Differential scanning calorimetric (DSC) runs were taken at four different heating rates (5, 10, 15 and 20 K min-1) for this purpose. The heating rate dependence of the glass transition temperature (Tg) was studied using different non-isothermal methods. The activation energy of glass transition (Eg) was evaluated using Kissinger's relation and the theory of Moynihan. The composition dependence of Tg and E g is also discussed. © 2010 The Royal Swedish Academy of Sciences.
Characterization of novel SeTeSn Chalcogenide Glassy Alloy (STS ChGA) as shielding material: Case study of its resistance against γ-ray irradiation for nuclear waste immobilization applications
(Elsevier Ltd, 2019) Ankita Srivastava; S.D. Sharma; Neeraj Mehta
Intense investigations are in progress globally towards the immobilization of radioactive and non-radioactive nuclear waste by their direct vitrification or by using novel glassy materials as an alternate shield. In fact, the entire technologies and economies of nuclear waste immobilization have been envisaged in the future on the basis of these approaches. Use of the glassy materials for shielding purpose is an important step towards realizing this vision. The radiation-induced effects of γ-ray irradiation (60Co source, 4 kGy, 8kGy and 12 kGy doses) have been examined in a novel STS ChGA. The physicochemical properties of present STS ChGA have been compared before and after γ-ray irradiation. Analysis of the different properties reveals the non-linear and non-monotonic behavior with increase in the dose of γ-ray irradiation but it suggests the possibilities of the application of this novel material for radiation shielding. In view of practical application in nuclear waste immobilization, the present finding reveals the possibilities for development of innovative ChGA based shielding system with stable and controlled parameters (like thermal stability, glass forming ability, crystallization rate, hardness etc). An attempt has been also made for understanding the mechanisms of radiation-induced effects in the present study. © 2019 Elsevier Ltd. All rights reserved.
Characterization techniques for the study of thermally activated phase transitions and determination of thermophysical/kinetic properties
(Elsevier, 2020) Neeraj Mehta
The techniques for the thermal analysis of heat exchangers and related thermally activated phase transitions are comprised of a set of techniques. Generally, a controlled temperature program is used to assess the quantitative information by measuring the physical or thermophysical properties of a thermally activated phenomenon corresponding to a substance under consideration. In this chapter, some significant and useful thermal analysis techniques, such as differential thermal analysis (DTA), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and transient plane source (TPS), are discussed. These techniques are extremely responsive to the study of diversified thermal properties of various kinds of advanced functional materials that are sensitive to heat exchange under different circumstances. In a thermal analytical technique, generally, we measure the temperature-dependent variation in change in the physical properties of a material that is subjected to a well-organized temperature program. © 2020 Elsevier Inc. All rights reserved.
Comparative insights into structural and optical properties of ZnO/Ag/ZnO and Ag/ZnO/Ag ternary layer thin films
(Royal Society of Chemistry, 2025) S.S Salah Fouad; Laila Ibrahim Soliman; Eszter Erdélyiné Erdélyiné Baradács; N. F. Osman; M. Nabil; Mohamed Essam Sayed; János J. Tomán; Neeraj Mehta; Zoltán Erdélyi
The impact of the Ag layer position in ZnO/Ag/ZnO and Ag/ZnO/Ag ternary thin films (thickness: 50 nm) was studied. ZnO was synthesized using atomic layer deposition, while Ag was deposited via direct current (DC) magnetron sputtering. Structural and optical properties were analyzed using GIXRD, SEM, and elemental mapping. Key parameters, including thickness, mass density, crystallite size, dislocation density, and surface roughness, were evaluated. Optical characterization revealed that shifting the Ag layer from the interlayer ZnO/Ag/ZnO to the top and bottom layer Ag/ZnO/Ag reduces the absorption edge from 3.146 to 3.063 eV and the direct optical band gap from 3.24 to 3.14 eV, increasing the Urbach energy from 0.34 to 0.40 eV. These outcomes reveal that the position of the Ag layer significantly affects both structural and optical properties, suggesting potential applications in solar cells, thin-film transistors, and gas sensors. This journal is © The Royal Society of Chemistry, 2025
Composition dependence of thermo-dynamical and thermo-mechanical properties in SeTeSnGe chalcogenide glasses (ChGs)
(EDP Sciences, 2020) Shiv Kumar Pal; Neeraj Mehta; John C. Macdonald; Dipti Sharma
In this endeavor, we have synthesized novel quaternary glassy Se78-xTe20Sn2Gex (0x6) alloys by the well-known rapid cooling of melt under quenching technique, to study the effect of Germanium on thermodynamic and thermo-mechanical properties. In particular, we employed Differential Scanning Calorimetry (DSC) technique for the investigation of thermodynamic parameters (e.g., specific heat Cp and enthalpy ΔH) in the glass-transition-region (GTR). Differential Scanning Calorimetry (DSC) experiment was run under non-isothermal conditions. The thermo-mechanical parameters i.e., micro-hardness, micro-void volume, the energy of creation of micro-void, elasticity, density, compactness, and molar volume are also calculated. It was observed that there is a large increment in Cp values in the GTR. Further analysis shows that the Cp values above the GTR (i.e., C=Cpe equilibrium specific heat) and below the GTR (i.e., Cp=Cpg glass specific heat) are vastly composition dependent. The increment in specific heat value after Ge incorporation is explained in terms of molar volume.. © 2020 EDP Sciences. All rights reserved.