Browsing by Author "Kumar, R"

Now showing 1 - 18 of 18
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    Advances in Optical Visual Information Security: A Comprehensive Review
    (2024-01) Sachin; Kumar, R; Sakshi; Yadav, R; Reddy, S; Yadav, A; Singh, P
    In the modern era, the secure transmission and storage of information are among the utmost priorities. Optical security protocols have demonstrated significant advantages over digital counterparts, i.e., a high speed, a complex degree of freedom, physical parameters as keys (i.e., phase, wavelength, polarization, quantum properties of photons, multiplexing, etc.) and multi-dimension processing capabilities. This paper provides a comprehensive overview of optical cryptosystems developed over the years. We have also analyzed the trend in the growth of optical image encryption methods since their inception in 1995 based on the data collected from various literature libraries such as Google Scholar, IEEE Library and Science Direct Database. The security algorithms developed in the literature are focused on two major aspects, i.e., symmetric and asymmetric cryptosystems. A summary of state-of-the-art works is described based on these two aspects. Current challenges and future perspectives of the field are also discussed.
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    Advances in Optical Visual Information Security: A Comprehensive Review
    (2024-01) Sachin; Kumar, R; Sakshi; Yadav, R; Yadav, AK
    In the modern era, the secure transmission and storage of information are among the utmost priorities. Optical security protocols have demonstrated significant advantages over digital counterparts, i.e., a high speed, a complex degree of freedom, physical parameters as keys (i.e., phase, wavelength, polarization, quantum properties of photons, multiplexing, etc.) and multi-dimension processing capabilities. This paper provides a comprehensive overview of optical cryptosystems developed over the years. We have also analyzed the trend in the growth of optical image encryption methods since their inception in 1995 based on the data collected from various literature libraries such as Google Scholar, IEEE Library and Science Direct Database. The security algorithms developed in the literature are focused on two major aspects, i.e., symmetric and asymmetric cryptosystems. A summary of state-of-the-art works is described based on these two aspects. Current challenges and future perspectives of the field are also discussed.
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    Antibacterial action of acriflavine hydrochloride for eradication of the gastric pathogen Helicobacter pylori
    (2020-10) Tehlan, A; Karmakar, B; Paul, S; Kumar, R; Kaur, I
    Helicobacter pylori, a type 1 carcinogen, accounts for numerous gastric cancer-related deaths worldwide. Repurposing existing drugs or developing new ones for a combinatorial approach against increasing antimicrobial resistance is the need of the hour. This study highlights the efficacy of acriflavine hydrochloride (ACF-HCl) in inhibiting the growth of H. pylori reference strain and antibiotic-resistant clinical isolates at low concentrations. ACF-HCl inhibits H. pylori growth at MIC value 10 times less than that in Escherichia coli, another Gram-negative bacteria. Furthermore, ACF-HCl demonstrates synergistic effect with clarithromycin, a commonly used antibiotic against H. pylori. ACF-HCl treatment also eradicates H. pylori infection in the mice model efficiently. Our in vitro data indicate that bacterial membrane is the prime target. The novel action of ACF-HCl against antibiotic-resistant clinical isolates, synergistic effect with the conventional antibiotic clarithromycin and eradication of H. pylori from infected mice highlight the potential of ACF-HCl as a promising therapeutic agent against H. pylori by itself as well as for combinatorial therapy.
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    Assessment and Mapping of Riverine Flood Susceptibility (RFS) in India through Coupled Multicriteria Decision Making Models and Geospatial Techniques
    (2023-11) Kumar, R; Kumar, M; Tiwari, A
    Abstract: Progressive environmental and climatic changes have significantly increased hydrometeo rological threats all over the globe. Floods have gained global significance owing to their devastating impact and their capacity to cause economic and human loss. Accurate flood forecasting and the identification of high-risk areas are essential for preventing flood impacts and implementing strategic measures to mitigate flood-related damages. In this study, an assessment of the susceptibility to riverine flooding in India was conducted utilizing Multicriteria Decision making (MCDM) and an extensive geospatial database was created through the integration of fourteen geomorphological, meteorological, hydroclimatic, and anthropogenic factors. The coupled methodology incorporates a Fuzzy Analytical Hierarchy Process (FAHP) model, which utilizes Triangular Fuzzy Numbers (TFN) to determine the Importance Weights (IWs) of various parameters and their subclasses based on the Saaty scale. Based on the determined IWs, this study identifies proximity to rivers, drainage density, and mean annual rainfall as the key factors that contribute significantly to the occurrence of riverine floods. Furthermore, as the Geographic Information System (GIS) was employed to create the Riverine Flood Susceptibility (RFS) map of India by overlaying the weighted factors, it was found that high, moderate, and low susceptibility zones across the country span of 15.33%, 26.30%, and 31.35% of the total area of the country, respectively. The regions with the highest susceptibility to flooding are primarily concentrated in the Brahmaputra, Ganga, and Indus River basins, which happen to encompass a significant portion of the country’s agricultural land (334,492 km2 ) potentially posing a risk to India’s food security. Approximately 28.13% of built-up area in India falls in the highly susceptible zones, including cities such as Bardhaman, Silchar, Kharagpur, Howrah, Kolkata, Patna, Munger, Bareilly, Allahabad, Varanasi, Lucknow, and Muzaffarpur, which are particularly susceptible to flooding. RFS is moderate in the Kutch-Saurashtra-Luni, Western Ghats, and Krishna basins. On the other hand, areas on the outskirts of the Ganga, Indus, and Brahmaputra basins, as well as the middle and outer portions of the peninsular basins, show a relatively low likelihood of riverine flooding. The RFS map created in this research, with an 80.2% validation accuracy assessed through AUROC analysis, will function as a valuable resource for Indian policymakers, urban planners, and emergency management agencies. It will aid them in prioritizing and executing efficient strategies to reduce flood risks effectively.
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    Cool green-emissive Y2Si2O7:Tb3+ nanophosphor: auto-combustion synthesis and structural and photoluminescence characteristics with good thermal stability for lighting applications†
    (2024-05) Kumar, P; Singh, D; Kadyan, S; Kumar, H; Kumar, R
    A cheap, versatile, sustainable and energy-efficient gel-combustion method was applied to develop a series of green-emitting down-converted Y2Si2O7:Tb3+ (YPS:Tb3+) nanophosphors. Employing XRD-based Rietveld refinement approach, the phase purity and crystallographic evaluation of the produced phosphor were conducted, revealing a triclinic crystal with P 1 space group. EDX and TEM analyses were performed on the synthesized samples to determine their elemental composition and morphological properties. Diffuse reflectance spectra yielded 5.61 eV and 5.79 eV optical energy band gaps for the host and the optimized (0.04 mole of Tb3+) sample, respectively. UV light has the ability to excite the nanocrystalline phosphor in an efficient manner, leading to significant luminosity qualities attributed to the radiative relaxation of 5 D4 / 7 FJ (J = 6, 5, 4, 3). The bi-exponential decay function was derived by the PL decay curves. With an activation energy of 0.2206 eV, the Y1.96Si2O7:0.04Tb3+ phosphor exhibits good thermal quenching capabilities. Improved photometric attributes including CIE coordinates, CCT and color purity confirmed the green glow, indicating a strong competitor for cool-green emission in lighting applications
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    A correlation between fractal growth, water contact angle, and SERS intensity of R6G on ion beam nanostructured ultra-thin gold (Au) films
    (2023-03) Jasrotia, P; Priya, B; Kumar, R; Bishnoi, P; Vij, A; Kumar, T
    Introduction: This study focuses on the detection of rhodamine-6G using surface-enhanced Raman scattering (SERS) on gold nanostructures (AuNS) of different sizes. Ion beam irradiation has been carried out to tune the size of AuNS and investigate the underlying mechanisms of sputtering and diffusion that govern their growth. Additionally, the study established a correlation between fractal growth parameters, water contact angle, and SERS detection of R6G. The results of this study offer new insights into the mechanisms of SERS detection on roughened metallic surfaces. Methods: Thermal evaporation was used to deposit an Au thin film on a glass substrate. Subsequent 10 keV Ar+ irradiation was done on Au thin film for fluences ranging from 3×1014 to 3×1016 ions/cm2 to tune the size of AuNS. Rutherford backscattering spectroscopy (RBS) was used to confirm that the decrease in Au concentration under ion beam sputtering was responsible for the tuning in size and structure of AuNS. Fractal dimension (Df) and interface width (w) were used as statistical parameters to control the wettable characteristics of the AuNS surfaces. Results and discussion: The researchers found that the growth of AuNS was governed by ion beam induced sputtering and diffusion mechanisms. They established a correlation between fractal growth parameters, water contact angle, and SERS detection of R6G. They found that a higher surface coverage area of Au NPs with lower fractal dimensions and water contact angles favoured the SERS detection of R6G. This study provides new insights into the mechanisms of SERS detection on roughened metallic surfaces. It is found that the growth of AuNS was governed by ion beam-induced sputtering and diffusion mechanisms, and established a correlation between fractal growth parameters, water contact angle, and SERS detection of R6G. The findings of this study may have applications in the development of more sensitive and efficient SERS-based chemical sensors.
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    Exploring the Influence of Temperature and Time on the Formation and Properties of 3D Flower-Like MoS2 Nanostructures Synthesized via Hydrothermal Method
    (2023-08) Kumari, R; Kumar, R
    In this study, a simple hydrothermal method was employed to synthesize 3D flower-like MoS2 nanostructures. The influence of different synthesis temperatures on the structural, electronic, optical and morphological properties of the MoS2 nanostructures was thoroughly investigated, and the optimal temperature was identified as 220 °C. Additionally, we conducted further optimization to determine the most suitable reaction time, which was found to be 24 h. The characterization of the synthesized MoS2 nanostructures, employing various techniques such as X-ray diffraction, Raman spectroscopy, Mott-Schottky analysis, UV–vis- NIR spectroscopy and field emission scanning electron microscopy, unveiled well-defined crystallinity, reduced thickness and uniform morphology, under the optimized conditions. Notably, as the temperature increased from 180 °C to 220 °C, the band gap of MoS2 nanostructures exhibited a notable increase from 1.72 to 2.35 eV. The Mott-Schottky analysis further confirmed our findings, revealing lower values of flat band potential and carrier concentration for the optimized temperature (220 °C), indicative of higher crystallinity with fewer defects. These comprehensive findings not only underscore the significant impact of temperature and time on the properties of MoS2 nanostructures but also hold promising implications for diverse applications, including sensing, energy storage, as well as photocatalysis for hydrogen evolution reactions and organic pollutant degradation
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    Genome sequencing of SARS-CoV-2 omicron variants in Delhi reveals alterations in immunogenic regions in spike glycoprotein
    (2023-10) Shikha, S; Jogi, M; Jha, R; Kumar, R; Sah, T; Kumar, A
    The SARS-CoV-2 omicron variants keep accumulating a large number of mutations in the spike (S) protein, which contributes to greater transmissibility and a rapid rise to dominance within populations. The identification of mutations and their affinity to the cellular angiotensin-converting enzyme-2 (ACE-2) receptor and immune evasion in the Delhi NCR region was under acknowledged. The study identifies some mutations (Y505 reversion, G339H, and R346T/N) in genomes from Delhi, India, and their probable implications for altering the immune response and binding affinity for ACE-2. The spike mutations have influenced the neutralizing activity of antibodies against the omicron variant, which shows partial immune escape. However, researchers are currently exploring various mitigation strategies to tackle the potential decline in efficacy or effectiveness against existing and future variants of SARS-CoV-2. These strategies include modifying vaccines to target specific variants, such as the omicron variant, developing multivalent vaccine formulations, and exploring alternative delivery methods. To address this, it is also necessary to understand the impact of these mutations from a different perspective, especially in terms of alterations in antigenic determinants. In this study, we have done whole genome sequencing (WGS) of SARS-CoV-2 in COVID-19 samples from Delhi, NCR, and analyzed the spike’s mutation with an emphasis on antigenic alterations. The impact of mutation in terms of epitope formation, loss/gain of efficiency, and interaction of epitopes with antibodies has been studied. Some of the mutations or variant genomes seem to be the progenitors of the upcoming variants in India. Our analyses suggested that weakening interactions with antibodies may lead to immune resistance in the circulating genomes.
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    Hybrid Approach of Cotton Disease Detection for Enhanced Crop Health and Yield
    (2024-07) Kumar, R; Kumar, A; Bhatia, K; Nisar, K; Chouhan, S; Maratha, P; Tiwari, A
    The well-being of cotton crops is of utmost importance for maintaining agricultural productivity, and the early detection of diseases plays a critical role in achieving this objective. This study introduces a comprehensive approach for creating a machine learning-based system capable of identifying diseases in cotton plants through the analysis of leaf images. The research encompasses stages such as acquiring the dataset, pre-processing the data, training the model, developing an ensemble model, evaluating the models, and analyzing the results. Several machine-learning models are trained and evaluated to determine how well they can classify cotton leaves as "Healthy" or "Diseased." These models include Random Forest, Support Vector Machine (SVM), Multi-Class SVM, and an Ensemble model. This investigation yields a practical and visually informative system for disease detection, which can contribute to disease prevention, thereby enhancing both crop yield and quality. This work underscores the significance of continuous improvement by periodically updating the models and explores the potential of advanced techniques such as deep learning.
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    Laplacian atom search optimization algorithm: development and application for harmonic estimator design
    (2024-04) Saxena, A; Shekhawat, S; Kumar, R; Mehta, A; Jangid, J
    Harmonics, are the major source of contaminations in fundamental voltage and current signals. For consumer satisfaction and for better equipment performance, these contaminations shall be identified and mitigated. Although, for accurate identification of harmonics, several methods have been proposed, yet metaheuristic based approaches have been used and in practice, since last two decades. The work reported here is based on a newly proposed optimization algorithm named as Atom Search Optimisation (ASO). In the first phase, a variant of ASO is proposed, based on Laplacian operator based position update mechanism named as Laplacian-ASO (L-ASO) for enhancing the performance of ASO and in the next phase, application of a newly developed L-ASO is carried out on harmonic estimator design problems. The improvisation of our proposed L-ASO is validated through con ducted analyses and results showcased in the discussion section.
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    Lycium shawii mediated green synthesis of silver nanoparticles, characterization and assessments of their phytochemical, antioxidant, antimicrobial properties
    (2023-12) Kaur, N; Kumar, R; Alhan, S; Sharma, H; Singh, N
    BACKGROUND: The shrub Lycium shawii belongs to the Solanaceae family, formerly used by ancestors to cure different illnesses. Dried leaves of Lycium shawii were used for extraction by maceration method in distilled water and methanol. Qualitative and quantitative estimation of phytochemicals were carried out in crude extracts. Plant-based silver nanoparticles have been praised over past decades as it is economical, environment-friendly, non-pathogenic, and undemanding. This study includes the synthesis of silver nanoparticles using crude leaf extract of Lycium shawii, their characterization, and exploited for different biological activities. FINDINGS: In phytochemical analysis, the total phenolic content in the methanolic extract was 11.11 mg Gallic acid/g, and the total flavonoid content was 7.76 mg Quercetin/g. The average size of aqueous-silver nanoparticles and methanolic-silver-nanoparticles was 64 nm and 79 nm, respectively. Crude extracts and nanoparticles showed remarkable antimicrobial potential against the gram-negative bacteria Salmonella enterica and fungi Rhizopus oryzae. The antioxidant potential of methanolic extract and MeOH-AgNPs manifests more significant activity than aqueous extract and Aq-AgNPs. Minimum inhibitory concentration was observed in a range of 1 mg/ml to 15 mg/ml against different microbes. The observed MIC clearly indicated that the syn thesized nanoparticles have strong antimicrobial potential. Hence can be used as a good source for the devel opment of new drugs against resistant microbes. CONCLUSION: In the era of increased antibiotic resistance, the Lycium shawii-mediated silver nanoparticle shows remarkable antimicrobial and significant antioxidant potential. These nanoparticles can be used alone or in combination with antibiotics to combat the effect of multidrug-resistant pathogens. Regarding the novelty, probably this is the first study highlighting the different biological activity of Lycium shawii-mediated silver nanoparticles.
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    Microbial World: Recent Developments in Health, Agriculture and Environmental Sciences
    (2021-03) Dhingra, G; Saxena, A; Nigam, A; Hira, P; Singhvi, N; Anand, S; Kaur, J; Kaur, J; Dua, A; Negi, N; Gupta, V; Sood, U; Kumar, R; Lal, S; Verma, H; Verma, M; Singh, P; Rawat, C; Tripathi, C; Talwar, C; Nagar, S; Mahato, N; Om Prakash; Singh, M; Kuhad, R.C.
    An Annual Conference Organized by Association of Microbiologists of India and Indian Network for Soil Contamination Research.
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    Realization of a green-emitting pyrosilicate structured Er3+-activated Y2Si2O7 phosphor: a systematic study of opto-electronic characteristics and thermal stability for lighting applications
    (2024-05) Kumar, P; Singh, D; Singh, S; Kumar, H; Kumar, R
    A series of green-emitting Y2−xSi2O7:xEr3+ phosphors (x = 1–7 mol%) have been successfully synthesized using a straightforward gel-combustion method facilitated by urea. X-ray diffraction analysis provided specific patterns for samples, confirming a consistent triclinic phase across erbium-doped structures compared to undoped structures. Studies using TEM and EDX were conducted to identify the surface related characteristics and chemical composition of the synthesized nanophosphor, respectively. The band gap was determined to be 5.55 eV and 5.80 eV for the host material and optimal sample, respectively. The primary peak of excitation, observed at 379 nm, represents the highly sensitive electric dipole transition from the 4 I15/2 state to the 4 G11/2 level, suggesting that the prepared phosphors could effectively absorb NUV light for activation. The PL profiles of Y2−xSi2O7:xEr3+ (x = 1–7 mol%) phosphors demonstrate characteristic emissions at 409 nm (2 H9/2 / 4 I15/2), 522 nm (2 H11/2 / 4 I15/2), 553 nm (4 S3/2 / 4 I15/2) and 662 nm (4 F9/2 / 4 I15/2). In accordance with Dexter's theory, luminescence quenching observed at a concentration of 4 mol% Er3+ is attributed to dipole-quadrupole interactions. The optimal sample demonstrates excellent thermal stability, indicated by its luminescence at different temperatures and activation energy of 0.2641 eV. Additionally, the CIE, color purity and CCT values of the fabricated nanomaterials make it ideal for use in lighting applications.
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    Rebound or Cage Escape? The Role of the Rebound Barrier for the Reactivity of Non-Heme High-Valent FeIV=O species
    (2023) Kumar, R; Ansari, A; Comba, P
    Owing to their high reactivity and selectivity, variations in the spin ground state and a range of possible pathways, high-valent FeIV=O species are popular models with potential bioinspired applications. An interesting example of a structure–reactivity pattern is the detailed study with five nonheme amine-pyridine pentadentate ligand FeIV=O species, including N4py: [(L1 )FeIV= O]2+ (1), bntpen: [(L2 )FeIV=O]2+ (2), py2tacn: [(L3 )FeIV=O]2+ (3), and two isomeric bispidine derivatives: [(L4 )FeIV=O]2+ (4) and [(L5 )FeIV=O]2+ (5). In this set, the order of increasing reactivity in the hydroxylation of cyclohexane differs from that with cyclohexadiene as substrate. A comprehensive DFT, ab initio CASSCF/NEVPT2 and DLPNO-CCSD(T) study is presented to untangle the observed patterns. These are well reproduced when both activation barriers for the C H abstraction and the OH rebound are taken into account. An MO, NBO and deformation energy analysis reveals the importance of π(pyr) ! π*xz(FeIII-OH) electron donation for weakening the FeIII-OH bond and thus reducing the rebound barrier. This requires that pyridine rings are oriented perpendicularly to the FeIII-OH bond and this is a subtle but crucial point in ligand design for non heme iron alkane hydroxylation.
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    Remediation of toluidine blue O dye from aqueous solution using surface functionalized magnetite nanoparticles
    (2024) Jangra, A; Kumar, R; Singh, D; Kumar, H; Kumar, J; Kumar, P; Kumar, S
    In the current study, tannic acid-functionalized iron oxide nanoparticles have been synthesized using a cost-effective co-pre cipitation method and subsequently characterized using various instrumentation techniques such as Fourier transform infrared spectroscopy, X-ray diffractometer, field emission scanning electron microscopy, and thermal gravimetric analysis. Further, these surface-modified magnetite nanoparticles have been used for the adsorption of toluidine dye from an aqueous solution. The adsorption process was accompanied using batch procedure, and influences of several factors such as adsorbent dose, contact time, pH, temperature, and initial concentration of adsorbate were inspected concurrently. The maximum adsorp tion capacity of tannic acid-functionalized magnetite nanoparticles was found to be 50.68 mg/g. The adsorption process was observed to follow the Temkin isotherm model, whereas the kinetic study was well described by pseudo-second order. The thermodynamic study revealed the adsorption process to be endothermic and spontaneous in nature with a high degree of freedom between adsorbent and adsorbate. Therefore, the study indicated that the tannic acid-functionalized magnetite nano particles have promising adsorption capability and can be used as an excellent adsorbent for the removal of toluidine blue O dye from the aqueous solution.
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    Visible-Light-Driven Photocatalytic Degradation of Tetracycline Using Heterostructure Cu2O−TiO2 Nanotubes, Kinetics, and Toxicity Evaluation of Degraded Products on Cell Lines
    (2022-09) Sharma, M; Mandal, M; Pandey, S; Kumar, R
    This study first reports on the tetracycline photodegradation with thesynthesizedheterostructuredtitaniumoxidenanotubescoupledwithcuprous oxide photocatalyst. The large surface area andmore active sites onTiO2 nanotubes with a reduced band gap (coupling of Cu2O) provide faster photodegradation of tetracycline under visible light conditions. Cytotoxicity experiments performed on theRAW264.7 (mousemacro phage) andTHP-1 (humanmono cytes)cell lines of tetracycline and the photodegradedproductsof tetracyclineaswellasquenchingexperiments werealsoperformed.Theeffectsof different parameters likepH, photocatalyst loadingconcentration, cuprousoxide concentration, and tetracycline load on the photodegradation rate were investigated.Withanenhancedsurfaceareaof nanotubes anda reducedband gap of 2.58 eV, 1.5 g/L concentration of 10%C-TAC showed the highest efficiencyofvisible-light-drivenphotodegradation(∼100%photodegradationrate in60min)of tetracyclineatpH5,7, and9.Thephotodegradationefficiencyisnotdepleteduptofiveconsecutivebatchcycles. Quenchingexperiments confirmed that superoxide radicals andhydroxyl radicals are themost involved reactive species in the photodegradationoftetracycline,whilevalancebandelectronsaretheleastinvolvedreactivespecies.Thecytotoxicitypercentageof tetracyclineanditsdegradedproductsonRAW264.7(−0.932)aswellasTHP-1(-0.931)showedanegativecorrelationwiththe degradationpercentagewith a p-value of 0.01. The toxicity-free effluent of photodegradation suggests the applicationof the synthesizedphotocatalyst inwastewater treatment.