Browsing by Author "Kumar, Amit"

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Characteristics of surge-type tributary glaciers, Karakoram
(Elsevier B.V., 2022-02-10T00:00:00) Bhambri, Rakesh; Hewitt, Kenneth; Haritashya, Umesh K.; Chand, Pritam; Kumar, Amit; Verma, Akshaya; Tiwari, Sameer Kumar; Rai, Santosh Kumar
The Karakoram has a large concentration of surge-type glaciers, including 69 tributary glaciers, compared to 152 surge-type main or trunk glaciers. The paper addresses the interactions between tributary and trunk glaciers using digital elevation models (DEMs), surface displacement, field and archival reports. In particular, it explores the behavior and impacts of 13 tributary glacier surges on three trunk glaciers, namely the Hispar, Braldu and Panmah. Observations include five surge tributaries of Panmah, five of Braldu, and three of Hispar. We observed ASTER DEMs can help in some cases to detect surge signature where automated surface displacement does not detect the surge. We also observed substantial differences in surge dimensions, timing and histories of the main trunk glacier and their tributaries. East Braldu III tributary surged between 2000 and 2003, whereas East Braldu IV surged from 2003 to 2006, but in these periods, no other tributary shows surge signature. Between 2013 and 2016, Braldu trunk Glacier surged along with four tributaries out of five except West Braldu I. Volumes and geometry of ice transferred from tributary to trunk glaciers are unique to each case, but the surging ice melted rapidly in about 2 to 4 years for some cases such as Little Skamri and Drenmang. The tributary ice modified all studied trunk glacier dynamics, morphology, distribution of debris and hypsography. The ice transferred from tributaries such as Little Skamri and Drenmang blocked the flow of trunk Nobande Sobonde Glacier from 2004 to 2006. Such ice transfer by surge tributaries to the main trunk glacier is referred here as surge-modified ice. It introduces indirect and post-surge effects and complicates or delay in tracking glacier responses to climate change. Also, mass balance in surge-type and surge-modified glaciers differ from systematic direct responses to climate in non-surge-type glaciers. Therefore, more research and monitoring are required to address the distinct responses of such glaciers and individual tributaries to better understand the heterogeneity of surging glaciers in Karakoram. � 2022 Elsevier B.V.
Chemical composition, in�vitro and in silico evaluation of essential oil from Eucalyptus tereticornis leaves for lung cancer
(Taylor and Francis Ltd., 2022-08-08T00:00:00) Anju; Kumar, Amit; Yadav, Poonam; Navik, Umashanker; Jaitak, Vikas
Chemical composition of the essential oil (EO) of Eucalyptus tereticornis leaves was studied by gas chromatography�mass spectrometry. Forty-five constituents were identified in the oil hydrodistilled from the sample collected from Ghudda Village, Bathinda (Pb), India of which eucalyptol (34.39%) and ledol (9.92%) were the major constituents. In vitro antioxidant and anticancer potential of EO was analysed by DPPH 2,2-diphenylpicrylhydrazyl (DPPH) and MTT assay. The percentage free radical scavenging activity was found to be 63.77%. The antiproliferative activity was analysed using MTT assay in adenocarcinomic human alveolar basal epithelial A549 cancer cell line and showed IC50 value of 47.14 �g/ml. In silico study of EO, constituents were performed using Maestro 12.9 against EGFR (PDB ID-2RGP). Five constituents from EO showed high dockscore as compared to standard Mobicertinib which indicated the effectiveness of oil constituents against lung cancer. � 2022 Informa UK Limited, trading as Taylor & Francis Group.
Efficacy of p-coumaric acid in chronic constriction injury induced neuropathic pain in rats
(Indian Drug Manufacturers' Association, 2021-12-14T00:00:00) Bharti, Akash; Kaur, Jaspreet; Kumar, Amit; Singh, Simranjit; Kumar, Deepak
The present research work has been designed to evaluate the effect of p-coumaric acid in chronic constriction injury (CCI) of sciatic nerve induced neuropathic pain in rats. In addition, biochemical tests such as thiobarbituric acid reactive substances (TBARS), reduced glutathione (GSH) and total protein were performed in sciatic nerve tissue sample. The neuropathic pain has been effi ciently and successfully induced in rat by the performance of CCI. The battery of behavioural test showed the development of neuropathic pain as an index of rising the paw and tail thermal and mechanical pain sensitivity. The treatment of p-coumaric acid at dose 50 and 100 mg kg-1, p.o. for 15 consecutive days have been shown to produce signifi cant ameliorative effect on CCI of sciatic nerve induced neuropathic pain sensitivity. In addition, CCI of sciatic nerve also induces the oxidative stress in nervous system by rising TBARS, decrease GSH and proteins levels in sciatic nerve tissue and these effects are reversed via administration of p-coumaric acid and statistically equivalent to standard drug. Hence, it may be concluded that, p-coumaric acid can be useful in the management of neuropathic pain symptoms. � 2021 Indian Drug Manufacturers' Association. All rights reserved.
Engagement of phytoestrogens in breast cancer suppression: Structural classification and mechanistic approach
(Elsevier Masson s.r.l., 2020-11-24T00:00:00) Tanwar, Ankur Kumar; Dhiman, Neha; Kumar, Amit; Jaitak, Vikas
Cancer is the world's devastating disease, and breast cancer is the most common reason for the death of women worldwide. Many synthetic drugs and medications are provided with their beneficial actions, but all of these have side effects and resistance problems. Natural remedies are coming forward to overcome the disadvantages of synthetic drugs. Among the natural categories, phytoestrogens having a structural similarity of mammalian oestradiol proves its benefit with various mechanisms not only in the treatment of breast cancer but even to prevent the occurrence of postmenopausal symptoms. Phytoestrogens are plant-derived compounds that were utilized in ancient medications and traditional knowledge for its sex hormone properties. Phytoestrogens exert pleiotropic effects on cellular signalling and show effects on estrogen-dependent diseases. However, because of activation/inhibition of steroid hormonal receptor ER-? or ER-?, these compounds induce or inhibit steroid hormonal (estrogen) action and, therefore, have the potential to disrupt hormone (estrogen) signalling pathway. In this review, we have discussed and summarize the effect of certain phytoestrogens and their possible mechanisms that can substantiate advantageous benefits for the treatment of post-menopausal symptoms as well as for breast cancer. � 2020 Elsevier Masson SAS
Enhanced Curie temperature and superior temperature stability by site selected doping in BCZT based lead-free ceramics
(Elsevier Ltd, 2022-01-31T00:00:00) Kumari, Sapna; Kumar, Amit; Kumar, Aman; Kumar, V.; Thakur, Vikas N.; Kumar, Ashok; Goyal, P.K.; Gaur, Anurag; Arya, Anil; Sharma, A.L.
In this work, Bi3+ doped Ba0.98-3x/2BixCa0.02Zr0.02Ti0.976Cu0.008O3 [0 ? x ? 0.03] lead free ceramics, to be employed for structural, dielectric and ferroelectric studies, have been synthesized via conventional solid state reaction method. Rietveld refinement of the X-ray diffraction (XRD) data evidences the existence of a pure perovskite phase with tetragonal symmetry for all ceramics. The Scanning Electron Microscopy (SEM) reveals that the grain size, which is 16.14 ?m for x = 0 reduced to 2.11 ?m for x = 0.03. Dielectric studies demonstrate excellent dielectric behavior with high Curie temperature (TC ?159 �C), high dielectric constant (?r ?834, ?max ? 3146), and a low dielectric loss (tan? ? 0.019), for an optimum value of x = 0.02. The analysis of temperature coefficient of the dielectric permittivity indicates the applicability of these materials in multilayer ceramic capacitors. Impedance studies, conducted to understand the underlying physical mechanisms, are found to be in good agreement with the results of structural and dielectric studies. Furthermore, the ferroelectric measurement confirms the ferroelectric nature for all samples with an energy storage efficiency (?) of ?42% for x = 0.02 composition. � 2022 Elsevier Ltd and Techna Group S.r.l.
Flavonoids as P-glycoprotein inhibitors for multidrug resistance in cancer: an in-silico approach
(Taylor and Francis Ltd., 2022-09-19T00:00:00) Kumar, Amit; Kalra, Sourav; Jangid, Kailash; Jaitak, Vikas
Cancer has become a leading cause of mortality due to non-communicable diseases after cardiovascular disease worldwide and is increasing day by day at a daunting pace. According to an estimate by 2040 there will be 28.4 million cancer cases. Occurrence of multidrug resistance has further worsened the scenario of available cancer treatment. Among different mechanisms of multidrug resistance efflux of xenobiotics by ABC transporter is of prime importance. P-glycoprotein (P-gp) is the major factor behind occurrence of multidrug resistance due to its wide distribution and invariably big binding cavity. Various generations of chemical inhibitors for P-gp have been designed and tested are not devoid of major side effects. Thus, in present study flavonoids a major class of natural compounds was virtually screened in order to find molecules which can be used as selective P-gp inhibitors to be used along with chemotherapeutics. After screening 4275 molecules from different classes of flavonoids i.e. flavan, flavanol, flavonone, flavone, anthocyanins, and isoflavone, through Glide docking top ten hit molecules were selected based on their binding affinity, binding energy calculation and pharmacokinetic properties. All the hit molecules were found to have docking score within the range of ?11.202 to ?9.699 kcal/mol showing very strong interaction with the amino acid residues of binding pocket. Whereas, dock score of standard P-gp inhibitor verapamil was ?4.984 kcal/mol. The ligand and protein complex were found to be quite stable while run through molecular dynamics simulations. Communicated by Ramaswamy H. Sarma. � 2022 Informa UK Limited, trading as Taylor & Francis Group.
Identification of 1,3,4-oxadiazoles as tubulin-targeted anticancer agents: a combined field-based 3D-QSAR, pharmacophore model-based virtual screening, molecular docking, molecular dynamics simulation, and density functional theory calculation approach
(Taylor and Francis Ltd., 2023-09-11T00:00:00) Das, Agnidipta; Sarangi, Manaswini; Jangid, Kailash; Kumar, Vijay; Kumar, Amit; Singh, Praval Pratap; Kaur, Kamalpreet; Kumar, Vinod; Chakraborty, Sudip; Jaitak, Vikas
Cancer is one of the most prominent causes of death worldwide and tubulin is a crucial protein of cytoskeleton that maintains essential cellular functions including cell division as well as cell signalling, that makes an attractive drug target for cancer drug development. 1,3,4-oxadiazoles disrupt microtubule causing G2-M phase cell cycle arrest and provide anti-proliferative effect. In this study, field-based 3D-QSAR models were developed using 62 bioactive anti-tubulin 1,3,4-oxadiazoles. The best model characterized by PLS factor 7 was rigorously validated using various statistical parameters. Generated 3D-QSAR model having high degree of confidence showed favourable and unfavourable contours around 1,3,4-oxadiazole core that assisted in defining proper spatial positioning of desired functional groups for better bioactivity. A five featured pharmacophore model (AAHHR_1) was developed using same ligand library and validated through enrichment analysis (BEDROC160.9 value = 0.59, Average EF 1% = 27.05, and AUC = 0.74). Total 30,212 derivatives of 1,3,4-oxadiazole obtained from PubChem database was prefiltered through validated pharmacophore model and docked in XP mode on binding cavity of tubulin protein (PDB code: 1SA0) which led into the identification of 11 HITs having docking scores between ?7.530 and ?9.719 kcal/mol while the reference compound Colchicine exerted docking score of ?7.046 kcal/mol. Following the analysis of MM-GBSA and ADME studies, HIT1 and HIT4 emerged as the two promising hits. To verify their thermodynamic stability at the target site, molecular dynamic simulations were carried out. Both HITs were further subjected to DFT analysis to determine their HOMO-LUMO energy gap for ensuring their biological feasibility. Finally, molecular docking based structural exploration for 1,3,4-oxadiazoles to set up a lead of Formula I for further advancements of tubulin polymerization inhibitors as anti-cancer agents. Communicated by Ramaswamy H. Sarma. � 2023 Informa UK Limited, trading as Taylor & Francis Group.
Identification of terpenoids as dihydropteroate synthase and dihydrofolate reductase inhibitors through structure-based virtual screening and molecular dynamic simulations
(Taylor and Francis Ltd., 2023-05-13T00:00:00) Saini, Abhishek; Kumar, Amit; Jangid, Kailash; Kumar, Vinod; Jaitak, Vikas
Bacterial infections are rising, and antimicrobial resistance (AMR) in bacteria has worsened the scenario, requiring extensive research to find alternative therapeutic agents. Terpenoids play an essential role in protecting plants from herbivores and pathogens. The present study was designed to focus on in silico evaluation of terpenoids for their affinity towards two necessary enzymes, i.e. DHFR and DHPS, which are involved in forming 5, 6, 7, 8-tetrahydrofolate, a key component in bacterial DNA synthesis proteins. Additionally, to account for activity against resistant bacteria, their affinity towards the L28R mutant of DHFR was also assessed in the study. The structure-based drug design approach was used to screen the compound library of terpenes for their interaction with active sites of DHFR and DHPS. Further, compounds were screened based on their dock score, pharmacokinetic properties, and binding affinities. A total of five compounds for each target protein were screened, having dock scores better than their respective standard drug molecules. CNP0169378 (?8.4 kcal/mol) and CNP0309455 (?6.5 kcal/mol) have been identified as molecules with a higher affinity toward the targets of DHFR and DHPS, respectively. At the same time, one molecule CNP0298407 (?5.8 kcal/mol for DHPS, ?7.6 kcal/mol for DHFR, ?6.1 kcal/mol for the L28R variant), has affinity for both proteins (6XG5 and 6XG4). All the molecules have good pharmacokinetic properties. We further validated the docking study by binding free energy calculations using the MM/GBSA approach and molecular dynamics simulations. Communicated by Ramaswamy H. Sarma. � 2023 Informa UK Limited, trading as Taylor & Francis Group.
Natural products as multidrug resistance modulators in cancer
(Elsevier, 2019) Kumar, Amit; Jaitak, Vikas
Cancer is a prominent cause of death globally. Currently, many drugs that are in clinical practice are having a high prevalence of side effect and multidrug resistance. Risk of tumors acquiring resistance to chemotherapy (multidrug resistance) remains a significant hurdle to the successful treatment of various types of cancer. Membrane-embedded drug transporters, generally overexpressed in cancer, are the leading cause among multiple mechanisms of multidrug resistance (MDR). P-glycoprotein (P-gp) also MDR1/ABCB1, multidrug resistance associated protein 1 (MRP1/ABCC1), MRP2 and breast cancer resistance protein (BCRP/ABCG2) are considered to be a prime factor for induction of MDR. To date, several chemical substances have been tested in a number of clinical trials for their MDR modulatory activity which are not having devoid of any side effects that necessitates to find newer and safer way to tackle the current problem of multidrug resistance in cancer. The present study systematically discusses the various classes of natural products i.e flavonoids, alkaloids, terpenoids, coumarins (from plants, marine, and microorganisms) as potential MDR modulators and/or as a source of promising lead compounds. Recently a bisbenzyl isoquinoline alkaloid namely tetrandrine, isolated from Chinese herb Stephania tetrandra (Han-Fang-Chi) is in clinical trials for its MDR reversal activity. © 2019 Elsevier Masson SAS
New pentacyclic triterpene from Potentilla atrosanguinea Lodd. as anticancer agent for breast cancer targeting estrogen receptor-?
(Taylor and Francis Ltd., 2021-10-04T00:00:00) Kumar, Amit; Gupta, Kunj Bihari; Dhiman, Monisha; Arora, Saroj; Jaitak, Vikas
One new (compound 3) along with two previously known ursane type triterpenoids (compounds 1 and 2) were purified by chromatographic techniques from ethyl acetate extract of aerial parts of Potentilla atrosanguniea and characterized by HRMS, 1 D and 2 D-NMR. Compounds 1 (ursolic acid), 2 (euscaphic acid) and 3 (3?,20?-dihydroxy 2-oxo-urs-12-en-28-oic acid) were tested for their antiproliferative activity along with standard bazedoxifene. Compounds 1 and 3 were found to be of higher activity (3.71 and 6.05 ?g/mL) as compared to compound 2 and bazedoxifene (IC50: 24.53 and 17.87 ?g/mL). Anti-estrogenic activity of three compounds on breast cancer (BC) were studied in vitro by accessing their antiproliferative activity and binding with estrogen receptor alpha (ER-?). All three compounds have effective binding affinity towards ER-? and decreased cell growth by downregulating the expression of mRNA and its translational protein as tested by semi-qRT-PCR and western blotting. In terms of effectiveness compounds 1 and 3 were found more active due to their antiproliferative, and antiestrogenic activity as compared to standard bazedoxifene. � 2021 Informa UK Limited, trading as Taylor & Francis Group.
New pentacyclic triterpene from Potentilla atrosanguinea Lodd. as anticancer agent for breast cancer targeting estrogen receptor-?
(Taylor and Francis Ltd., 2021-10-04T00:00:00) Kumar, Amit; Gupta, Kunj Bihari; Dhiman, Monisha; Arora, Saroj; Jaitak, Vikas
One new (compound 3) along with two previously known ursane type triterpenoids (compounds 1 and 2) were purified by chromatographic techniques from ethyl acetate extract of aerial parts of Potentilla atrosanguniea and characterized by HRMS, 1 D and 2 D-NMR. Compounds 1 (ursolic acid), 2 (euscaphic acid) and 3 (3?,20?-dihydroxy 2-oxo-urs-12-en-28-oic acid) were tested for their antiproliferative activity along with standard bazedoxifene. Compounds 1 and 3 were found to be of higher activity (3.71 and 6.05 ?g/mL) as compared to compound 2 and bazedoxifene (IC50: 24.53 and 17.87 ?g/mL). Anti-estrogenic activity of three compounds on breast cancer (BC) were studied in vitro by accessing their antiproliferative activity and binding with estrogen receptor alpha (ER-?). All three compounds have effective binding affinity towards ER-? and decreased cell growth by downregulating the expression of mRNA and its translational protein as tested by semi-qRT-PCR and western blotting. In terms of effectiveness compounds 1 and 3 were found more active due to their antiproliferative, and antiestrogenic activity as compared to standard bazedoxifene. � 2021 Informa UK Limited, trading as Taylor & Francis Group.
A note on "A fuzzy approach to transport optimization problem"
(Springer New York LLC, 2016) Sidhu, Sukhpreet Kaur; Kumar, Amit; Kaur, Amarpreet
Sudhagar and Ganesan (Optim Eng, 2012, doi:10.1007/s11081-012-9202-6) proposed an approach to find the fuzzy optimal solution of such fuzzy transportation problems in which all the parameters are represented by fuzzy numbers. In this note, it is pointed out that the authors have used some mathematical incorrect assumptions in their proposed method. ? 2015, Springer Science+Business Media New York.
Optimal way of selecting cities and conveyances for supplying coal in uncertain environment
(Springer India, 2014) Kumar, Amit; Kaur, Amarpreet
In this paper, the limitations and shortcomings of the existing methods for solving fuzzy solid transportation problem are pointed out and to overcome these shortcomings, a new method is proposed for solving fuzzy solid transportation problem. The advantages of the proposed method over the existing methods are discussed. To illustrate the proposed method, an existing fuzzy solid transportation problem is solved. Also, to show the application of the proposed method in real life problems an existing real life fuzzy solid transportation problem is solved by the proposed method. ? 2014 Indian Academy of Sciences.
Pharmacological and chemical potential of Cassia fistula L- a critical review
(Elsevier GmbH, 2020-10-19T00:00:00) Sharma, Akanksha; Kumar, Amit; Jaitak, Vikas
Cassia fistula L. (Fabaceae) is a plant species called �Aragvadha� which means �disease killer�. C. fistula consists of a large amount of medicinal properties. The plant has been used in Ayurvedic medicine since ancient periods, because it affects all three �Doshas� i.e. Vata, Pitah, and Kapha. In the last few years, the plant has been widely explored for its array of pharmacological uses which have also been experimentally proven. It contains many chemical components having important pharmacological properties. These constituents are reported to possess various biological activities such as antioxidant, antimicrobial, antidiabetic, antitumor and antimelasmic. This current article will be important to investigate Cassia fistula and explore it further for determination of new potential pharmacophores that could be responsible for its activities related to the central nervous system, heart, antitumor, antioxidant and inflammation. � 2020 Elsevier GmbH
Reassessing the Karakoram Through Historical Archives
(Springer International Publishing, 2022-11-11T00:00:00) Bhambri, Rakesh; Chand, Pritam; N�sser, Marcus; Kawishwar, Prashant; Kumar, Amit; Gupta, Anil K.; Verma, Akshaya; Tiwari, Sameer K.
The Karakoram region is an integral part of the Hindu Kush�Karakoram�Himalaya (HKH) mountain system and forms the great divide between the drainage of the Indus and Tarim basins. This region has a substantial geographical, historical, economical, cultural, and geopolitical importance owing to its location, rugged topography, distinct climate regime, and the presence of numerous glaciers. It acts as a water tower where its unique assemblage paved the way for developing ancient trade routes facilitating cultural exchange between Central Asia and the Indian subcontinent. It has attracted a large number of expeditions and scientific studies for more than 200 years, bringing significant advances in geographical knowledge. However, the spatial extent of the Karakoram in many studies particularly during the 2010s exhibits a large inconsistency. We, therefore, complied ?100 maps and vast literature to present the evolution of the geographical term �the Karakoram� and its spatial extent based on historical archives. We also provide a digital outline of the Karakoram region using GIS tools based on descriptive enumerations of the Royal Geographical Society (RGS) and the Survey of India (SoI) which we hope will provide new insight for a wide range of scientific disciplines, including geography, glaciology, geology, history, and cartography. � The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2022.
Reconnoitering the transformative journey of minocycline from an antibiotic to an antiepileptic drug
(Elsevier Inc., 2022-01-20T00:00:00) Singh, Tanveer; Thapliyal, Surabhi; Bhatia, Shiveena; Singh, Varinder; Singh, Manjinder; Singh, Hasandeep; Kumar, Amit; Mishra, Awanish
Minocycline, a second-generation tetracycline antibiotic is being widely tested in animals as well as clinical settings for the management of multiple neurological disorders. The drug has shown to exert protective action in a multitude of neurological disorders including spinal-cord injury, stroke, multiple sclerosis, amyotrophic lateral sclerosis, Huntington's disease, and Parkinson's disease. Being highly lipophilic, minocycline easily penetrates the blood brain barrier and is claimed to have excellent oral absorption (~100% bioavailability). Minocycline possesses anti-inflammatory, immunomodulatory, and anti-apoptotic properties, thereby supporting its use in treating neurological disorders. The article henceforth reviews all the recent advances in the transformation of this antibiotic into a potential antiepileptic/antiepileptogenic agent. The article also gives an account of all the clinical trials undertaken till now validating the antiepileptic potential of minocycline. Based on the reported studies, minocycline seems to be an important molecule for treating epilepsy. However, the practical therapeutic implementations of this molecule require extensive mechanism-based in-vitro (cell culture) and in-vivo (animal models) studies followed by its testing in randomized, placebo controlled and double-blind clinical trials in large population as well as in different form of epilepsies. � 2022
Role of sintering temperature in tailoring the electrical properties of 0.98KNNS�0.02BNZSH piezoelectric ceramics
(Springer, 2023-02-16T00:00:00) Kumar, Amit; Kumari, Sapna; Kumar, V.; Kumar, Ashok; Goyal, P.K.; Aggarwal, Sanjeev; Arya, Anil; Sharma, A.L.
Lead-free 0.98(K0.5Na0.5)(Nb0.96Sb0.04O3)�0.02(Bi0.5Na0.5)(Zr0.8Sn0.1Hf0.1)O3 (0.98KNNS�0.02BNZSH) perovskite ferroelectric ceramics have been designed and prepared through the traditional ceramic fabrication technique. To have an insight on the effects of sintering temperature (in the range from 1020 to 1110��C), the structural, microstructural, dielectric and ferro/piezoelectric properties of 0.98KNNS�0.02BNZSH ceramics are investigated systematically. The structural analysis has revealed a pure perovskite phase for sintering at different temperatures. The rhombohedral (R) and orthorhombic (O) phases coexist for sintering of 0.98KNNS�0.02BNZSH ceramic at 1080��C, while the rhombohedral phase dominates above 1080��C. The grains become more uniform and tightly packed when the sintering temperature is increased from 1020 to 1080��C. However, the grain size and the density have been revealed to be decreased for samples sintered above 1080��C. The conduction behavior of 0.98KNNS�0.02BNZSH ceramics has also been investigated using complex impedance spectroscopy. The optimum values of different dielectric and ferro/piezoelectric parameters for 0.98KNNS�0.02BNZSH ceramics sintered at 1080��C are obtained to be as the following: TC ~ 317��C, ?max ~ 7102, tan? ~ 0.10, ? ~ 4.49�g/cm3, d33 ~ 180 pC/N, and Pr ~ 16.7 �C/cm2. These findings show that crystallizability, density, and electrical properties are significantly influenced by the sintering temperature. � 2023, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.
Structural, dielectric and ferroelectric properties of Cu2+- and Cu2+/Bi3+-doped BCZT lead-free ceramics: a comparative study
(Springer, 2021-05-29T00:00:00) Kumari, Sapna; Kumar, Amit; Kumar, V.; Dubey, S.K.; Goyal, P.K.; Kumar, Suresh; Sharma, A.L.; Arya, Anil
Perovskite-type Ba0.98Ca0.02Zr0.02Ti0.98O3 (BCZT), Ba0.98Ca0.02Zr0.02Ti0.976Cu0.008O3 (BCZTC) and Ba0.9725Bi0.005Ca0.02Zr0.02Ti0.976Cu0.008O3 (BCZTCB) lead-free ceramics were synthesised via solid-state reaction method at a sintering temperature of 1380��C. Effects of CuO and Bi2O3/CuO doping on structural, microstructural, dielectric and ferroelectric properties were investigated systematically. X-ray diffraction technique confirmed the existence of pure perovskite phase with the tetragonal structure in pure and in the doped BCZT ceramics at room temperature. The dielectric analysis demonstrated two anomalies around 24��C and 126��C for BCZT, which were identified as orthorhombic to tetragonal (TO-T) and tetragonal to cubic (TC) phase transition temperature, respectively. The TO-T temperature shifted to below 16��C, while the TC increased to 132��C for the BCZTCB sample. The physical mechanisms of the conduction processes were investigated through impedance spectroscopy, and the values of resistance, conductivity and activation energies associated with the grain and grain boundaries were evaluated. The activation energy was determined to be higher for doped samples than for pure BCZT. Further, the dopant-dependent ferroelectric nature of the ceramic samples was evidenced by the analysis of characteristic hysteresis loop, and a value of remnant polarization (Pr = 4.59�?C/cm2) was obtained for the BCZTCB ceramic sample. Furthermore, the d33 value, which was 54 pC/N for pure BCZT, was determined to be 140 pC/N and 64 pC/N for BCZTC and BCZTCB, respectively. � 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.
Structure-based Virtual Screening and Molecular Dynamic Simulation Approach for the Identification of Terpenoids as Potential DPP-4 Inhibitors
(Bentham Science Publishers, 2023-05-16T00:00:00) Pulikkottil, Ajay Aravind; Kumar, Amit; Jangid, Kailash; Kumar, Vinod; Jaitak, Vikas
Background: Diabetes mellitus is a metabolic disorder where insulin secretion is compromised, leading to hyperglycemia. DPP-4 is a viable and safer target for type 2 diabetes mellitus. Computational tools have proven to be an asset in the process of drug discovery. Objective: In the present study, tools like structure-based virtual screening, MM/GBSA, and pharmacokinetic parameters were used to identify natural terpenoids as potential DPP-4 inhibitors for treating diabetes mellitus. Methods: Structure-based virtual screening, a cumulative mode of elimination technique, was adopted, identifying the top five potent hit compounds depending on the docking score and nonbonding interactions. Results: According to the docking data, the most important contributors to complex stability are hydrogen bonding, hydrophobic interactions, and Pi-Pi stacking interactions. The dock scores ranged from-6.492 to-5.484 kcal/mol, indicating robust ligand-protein interactions. The pharmacokinetic characteristics of top-scoring hits (CNP0309455, CNP0196061, CNP0122006, CNP0 221869, CNP0297378) were also computed in this study, confirming their safe administration in the human body. Also, based on the synthetic accessibility score, all top-scored hits are easily synthesizable. Compound CNP0309455 was quite stable during molecular dynamic simulation studies. Conclusion: Virtual database screening yielded new leads for developing DPP-4 inhibitors. As a result, the findings of this study can be used to design and develop natural terpenoids as DPP-4 inhibitors for the medication of diabetes mellitus. � 2024 Bentham Science Publishers.
Synthesis, phase confirmation and electrical properties of (1 ? x)KNNS?xBNZSH lead-free ceramics
(Springer, 2022-02-02T00:00:00) Kumar, Amit; Kumari, Sapna; Kumar, V.; Kumar, Prashant; Thakur, Vikas N.; Kumar, Ashok; Goyal, P.K.; Arya, Anil; Sharma, A.L.
In the present work, lead-free piezoelectric ceramics (Rx)(K0.5Na0.5)(Nb0.96Sb0.04O3)?x(Bi0.5Na0.5)(Zr0.8Sn0.1Hf0.1)O3 [abb. as (Rx)KNNS?xBNZSH, 0 ? x ? 0.04] were prepared via solid-state sintering technique. The thermal behavior of mixed powders has been investigated for x = 0, 0.02, and 0.04 using TGA-DSC analysis to estimate the calcination temperature. The structural, morphological, dielectric, ferroelectric and piezoelectric properties are analyzed through the appropriate characterization techniques. The X-ray diffraction (XRD) patterns demonstrate a pure perovskite phase structure for all the sintered samples. Further, the coexistence of rhombohedral to orthorhombic (R-O) phase is observed in ceramic sample with x = 0.02. The morphology of all the sintered samples exhibits an inhomogeneous, dense microstructure with the rectangular grain, while for x = 0.02, a relatively homogeneous distribution of grains is observed. BNZSH doping decreases the average grain size from 2.22 to 0.33�?m for x = 0 to x = 0.04, respectively. Owing to the presence of multiple-phase coexistence as well as the improved microstructure and enhanced dielectric properties (dielectric constant ?r = 1080, ?max = 5301; Curie temperature - TC ~ 317��C; dielectric loss - tan? ~ 6%) the ceramics with x = 0.02 has been found to have a large piezoelectric coefficient (d33) of ~180 pC/N, remnant polarization (Pr) ~ 16.7 �C/cm2 and coercive field (Ec) ~ 10.7�kV/cm. We believe it will expand the range of applications for KNN-based ceramics. � 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.