Browsing by Author "Brijesh Kumar"

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A flowchart for porosity and acoustic impedance mapping using seismic inversion with semi hybrid optimization combining simulated annealing and pattern search techniques
(Springer Science and Business Media B.V., 2024) Raghav Singh; S.P. Maurya; Brijesh Kumar; Nitin Verma; Alok Kumar Tiwari; Ravikant Tiwari; G. Hema; Ajay P. Singh
Porosity and acoustic impedance are important in the study of subsurface properties of rocks and soil. Porosity is influenced by the type of minerals, and fluids, and their distribution within the subsurface material. Acoustic impedance is a key parameter in seismic inversion because it governs the reflection and transmission of seismic waves at interfaces between different rock layers. Mapping porosity and acoustic impedance using seismic inversion poses several challenges such as low resolution, longer convergence times compared to other optimization techniques, and handling large datasets. To address these challenges, our current study has employed a semi-hybrid optimization approach by incorporating a pattern search (PS) method into the globally recognized simulated annealing (SA) technique. In our devised methodology, seismic data is meticulously inverted, trace by trace, initially utilizing the simulated annealing process and subsequently integrating the pattern search which further reduces computational Complexity. The output from SA serves as the foundation for the PS optimization, preventing it from getting trapped in local minima or maxima. To evaluate the algorithm, we initiated a systematic analysis using synthetic data. The hybrid optimization method performed well, yielding highly accurate inversion results with a remarkable high resolution and correlation between original and inverted impedance. We then applied this approach to actual seismic reflection data from the Blackfoot field in Alberta, Canada. Notably, the inversion identified a sand channel between 1055 and 1070 ms two-way travel time, characterized by low impedance and high porosity, suggesting the potential presence of hydrocarbon reservoirs. The level of performance demonstrated in this context may not be anticipated when utilizing SA or PS optimization alone. Hence, the newly devised semi-hybrid optimization approach emerges as a highly recommended solution, offering the potential to address the constraints of individual optimization methods and deliver thorough subsurface insights. © The Author(s), under exclusive licence to Springer Nature B.V. 2024.
A therapeutic approach to target mitochondrial dysfunction using molecular docking studies: Screening of natural drugs for oral carcinoma
(Wolters Kluwer Medknow Publications, 2018) Manish Singh; Manish Tripathi; Alok Singh; Chandra Azad; Indrajeet Gambhir; Brijesh Kumar; Suresh Purohit
Background: Mitochondrial dysfunction is the major cause of various types of cancer, leading to death worldwide. The present study investigated the in silico binding potential of natural flavonoids and essential oils with human cyclophilin D (CyPD) protein. CyPD protein is a major molecular marker for apoptosis and has been reported to be elevated in oral carcinoma. Methods: PubChem database was used to check the efficacy of different active phytoconstituents (kaempferol, quercetin, eugenol, oxyresveratrol, tanshinone 2a, catechin, epicatechin, cinnamaldehyde, and emodin). These compounds were used as ligands to check their potential as anticancer agents against the inner mitochondrial membrane protein, CyPD. Docking studies were performed with the help of Discovery Studio 2.5 and Autodock. Emodin was used as a reference inhibitor to compare the results. Results: The binding energy (B.E.) of the reference inhibitor (known/established drug) emodin was observed-28.9 kcal/mol while novel inhibitors (catechin, cinnamaldehyde, epicatechin, eugenol, kaempferol, oxyresveratrol, quercetin, and tanshinone 2a) exhibited a range from-51.51 to-5.89 kcal/mol. Quercetin, kaempferol, and epicatechin (B.E.:-51.51,-34.79, and-30.62 kcal/mol, respectively) showed strong affinity as compared to reference inhibitor (B.E.:-28.9 kcal/mol). Conclusion: Quercetin, kaempferol, and epicatechin can be used as lead inhibitors against targeting CyPD. © 2018 Pharmacognosy Magazine. Published by Wolters Kluwer.
A way to identify groundwater potential zones (GWPZS) in rocky Terrains (India)
(EM International, 2016) Brijesh Kumar; Virendra Kumar Chandola; Devendra Mohan; Kanhu Charan Patra
The objective of this study is to explore the way to find out sound groundwater potential zones in draught-prone rocky terrains. In the present paper, groundwater potential zones have been delineated using two aquifer parameters viz. transmissibility (T), storability (S) and GIS techniques. The transmissibility (T) and storability (S) values for different well location are being used to prepare two thematic raster layers viz. Isotransmissibility and Isostorability map using kriging interpolation method. Thereafter, these two maps have allocated an equal weight in weighted overlay technique of ArcGIS to get the weighted map. Thus, the obtained weighted map is groundwater potential zones map (GWPZs) and has six groundwater potential zones, viz., very good, good, moderate, poor, very poor and nil. The prepared thematic maps may prove very supportive to enhance planning and management of groundwater resources in these rocky terrains. Copyright © EM International.
Acetylsalicylic acid sensitized lasing luminescence of terbium complex in PVA: A case of energy avalanche via 1, 10-Phenanthroline
(Elsevier, 2017) Brijesh Kumar; Gagandeep Kaur; S.B. Rai
Ternary complexes of Terbium with acetylsalicylic acid (ASA) and 1, 10 Phenanthroline (Phen) were synthesized in PVA polymer film. The structural properties of the complex were evaluated using XRD and formation of complex was verified by FT-IR technique. The absorption, excitation and photoluminescence properties of the Tb3+ ion get improved when complexed with ASA and Phen ligands. Selective excitations of Tb3+, ASA and Phen revealed an efficient energy transfer enhancing green luminescence of Tb3+ ion on excitation with 355, 335 and 306 nm radiations respectively. The emission intensity arising from Tb(ASA)3Phen complex in PVA has been observed to be much more as compared to the one with Tb3+ ions only. The fluorescence decay time for Tb3+ (5D4 → 7F5 transition) is seen to increase from 557 μs in Tb3+ to 628 μs in presence of Tb(ASA)3Phen complex. The fluorescence decay time for Phen and ASA is seen to decrease from 4.43 ns to 1.64 ns and from 5.75 ns to 1.58 ns respectively in Tb(ASA)3Phen complex. This reflects an energy transfer from excited Phen to ASA and finally to Tb3+ is proposed as the cause of the above observations and thus an energy avalanche. The intense green luminescence on 266 nm excitation in Tb(ASA)3Phen complex in PVA with quantum yield of 0.32 shows a tendency towards lasing. © 2016 Elsevier B.V.
Acute and subacute toxicity study of ethanolic extract of Calotropis procera (Aiton) Dryand flower in Swiss albino mice
(Elsevier B.V., 2022) Ashutosh Kumar; Brijesh Kumar; Rajesh Kumar; Ajay Kumar; Manish Singh; Vinod Tiwari; Anshuman Trigunayat; Paramita Paul; Pratistha Singh
Background: Calotropis procera is a large shrub which consists many medicinal properties, used in treatment of snake bite, sinus fistula, rheumatism, mumps, burn injuries, inflammation and jaundice traditionally. All the parts of Calotropis procera were utilized in the treatment of diseases out of which leaves and roots were investigated for its toxicity profile that showed dose dependent toxicity. Toxicity profile of flowers of Calotropis procera was not investigated in the previous studies. The aim of this study was to explore the acute and subacute toxicity of ethanolic extract of Calotropis procera flowers for the safe use of traditional medicine. Method: In acute toxicity, a total of 20 female mice (Swiss albino), weighing between 23 and 32 g were randomly divided into four experimental groups: control, 300, 1000, and 2000 mg/kg groups with 5 mice each, and each received a single dose of extract at 300, 1000, or 2000 mg/kg, respectively. Animals were monitored for 14 days. In the subacute study, a total of 40 mice (23–32 g) were divided into 4 groups, each containing males and females. Group 1 (control group) received vehicle and groups 2, 3, and 4 received extract at doses of 300 mg/Kg, 1000 mg/Kg, 2000 mg/Kg of b.w., respectively, for 28 consecutive days. The study was conducted in compliance with the OECD guidelines 407 and 423. Results: Acute toxicity study showed no mortality at the dose of 2000 mg/Kg. In subacute toxicity study, statistical analysis of hematological and biochemical parameters showed no significant differences compared to control group except marked increase in segmented neutrophils. Histopathological studies revealed no significant structural differences among the treated groups and in comparison to control group. Conclusions: It was concluded that oral administration of doses of ethanolic extract of Calotropis procera flower, administered acutely, did not cause any mortality or notable changes at the dose of 2000 mg/Kg. Therefore, the approximate lethal dose (ALD) of in mice was higher than 2,000 mg/kg. In a 28-day subacute toxicity model, the extract did not cause any mortality, and no treatment-related changes were observed in body weight, organ weight, hematological and biochemical blood analysis, or histopathologic examinations at the extract dose of 2000 mg/Kg. These findings indicate that the no-observed-adverse-effect-level (NOAEL) of Calotropis procera flower ethanolic extract was greater than 2000 mg/kg/day. © 2022
Anomalous electrical properties of poly vinyl alcohol films with Tb3+ ions and copper nanoparticles in different solvents
(Royal Society of Chemistry, 2015) Brijesh Kumar; Gagandeep Kaur; Prabhakar Singh; S.B. Rai
Laser ablation was used to fabricate copper nanoparticles (NPs) in different solvents from sodium lauryl sulphate, acetone and ethanol by applying 1064 nm radiation from a Nd:YAG laser. The sizes and shapes of the colloidal Cu NPs were investigated by transmission electron microscopy (TEM). The electrical conductivities of Tb3+ in polymer films with Cu NPs were measured in the frequency range of 20 Hz to 1 MHz and the temperature range of 308-343 K. It was found that the electrical conductivity of Tb3+ was greater for larger Cu NPs with sizes ranging from 20-40 nm in ethanol as compared to Cu NPs with smaller dimensions formed in the other two solvents. It was concluded that using ethanol as the solvent enhanced the electrical conductivity of Tb3+ in the polymer film. The activation energy as well as the variation in the loss tangent with temperature also explains the enhanced electrical conductivity. This journal is © The Royal Society of Chemistry 2015.
Bacteriological Profile and Antibiogram of Ventilator Associated Pneumonia
(Springer, 2024) Shiva Manwatkar; Aditi Agarwal; Keerthy Reddy; Brijesh Kumar; Sucheta Barnawal; Anil Kumar Saroj; Sunil Kumar Rao
[No abstract available]
Bismuth functionalized PVA film: Field, plasmonic and pH effect on PVA originated broad photoluminescence
(Royal Society of Chemistry, 2016) Brijesh Kumar; Gagandeep Kaur; Rajesh Kumar Verma; A. Bahadur; S.B. Rai
Bismuth (Bi) NPs have been synthesized by Laser Ablation Synthesis in Solution (LASiS) at different pH in different aqueous solutions [viz. H2O (H), H2O + NaOH (HN), and H2O + HCl (HC)]. The NPs in aqueous solution have been characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and UV-Vis-NIR techniques. The NPs are spherical, core shell type and hollow spheres in H, HN and HC, respectively. The vibrational features have been studied using Raman technique and correlated with different states of NPs (neutral NPs, ionized NPs, hollow NPs, core shell type NPs and NPs complex, etc.). The NPs were later dispersed in polyvinyl alcohol (PVA). The electronic spectra of PVA molecules along with different types of Bi NPs films have been studied at different excitation wavelengths (λexci = 240 nm, 270 nm, 300 nm and 360 nm). The sequences of optical sensitization in increasing order are NPs, core shell type NPs, and hollow spherical NPs. The enhanced emission is discussed in terms of plasmonic and field effects and is verified by lifetime measurements. © 2016 The Royal Society of Chemistry.
Bismuth induced enhanced green emission from terbium ions and their complex in thin films
(Royal Society of Chemistry, 2014) Gagandeep Kaur; Brijesh Kumar; R.K. Verma; S.B. Rai
Bismuth nanoparticles (NPs) have been prepared by the pulsed laser ablation technique using the third harmonics of a Nd-YAG laser. UV-absorption and TEM micrographs show Bi NPs of spherical shape with the average particle size ranging from 15 to 20 nm. These NPs were dispersed with Tb3+ ions and their complex with salicylic acid (Sal) in polyvinyl alcohol to obtain thin films. The influence of Bi NPs on the emissive properties of Tb3+ ions and the [Tb(Sal)3(phen)] complex has been studied by luminescence spectroscopy using 266 nm and 355 nm as excitation wavelengths. The luminescence intensity of Tb3+ ions complexed with Sal in the thin polymer films increased significantly as compared to the Tb3+ ions in the presence of Bi NPs on excitation at 355 nm. However, terbium ions in the case of the [Tb(Sal)3(phen)] complex together with NPs show an intense and extended emission spectrum in the 375-700 nm range for transitions arising from 5D3 and 5D4 levels to different 7FJ levels on 266 nm excitation. The luminescence enhancement has also been supported by lifetime measurements. © 2014 the Partner Organisations.
Deciphering the landscape of triple negative breast cancer from microenvironment dynamics and molecular insights to biomarker analysis and therapeutic modalities
(John Wiley and Sons Inc, 2024) Harshita Tiwari; Swati Singh; Sonal Sharma; Priyamvada Gupta; Ashish Verma; Amrit Chattopadhaya; Brijesh Kumar; Sakshi Agarwal; Rajiv Kumar; Sanjeev Kumar Gupta; Vibhav Gautam
Triple negative breast cancer (TNBC) displays a notable challenge in clinical oncology due to its invasive nature which is attributed to the absence of progesterone receptor (PR), estrogen receptor (ER), and human epidermal growth factor receptor (HER-2). The heterogenous tumor microenvironment (TME) of TNBC is composed of diverse constituents that intricately interact to evade immune response and facilitate cancer progression and metastasis. Based on molecular gene expression, TNBC is classified into four molecular subtypes: basal-like (BL1 and BL2), luminal androgen receptor (LAR), immunomodulatory (IM), and mesenchymal. TNBC is an aggressive histological variant with adverse prognosis and poor therapeutic response. The lack of response in most of the TNBC patients could be attributed to the heterogeneity of the disease, highlighting the need for more effective treatments and reliable prognostic biomarkers. Targeting certain signaling pathways and their components has emerged as a promising therapeutic strategy for improving patient outcomes. In this review, we have summarized the interactions among various components of the dynamic TME in TNBC and discussed the classification of its molecular subtypes. Moreover, the purpose of this review is to compile and provide an overview of the most recent data about recently discovered novel TNBC biomarkers and targeted therapeutics that have proven successful in treating metastatic TNBC. The emergence of novel therapeutic strategies such as chemoimmunotherapy, chimeric antigen receptor (CAR)-T cells-based immunotherapy, phytometabolites-mediated natural therapy, photodynamic and photothermal approaches have made a significant positive impact and have paved the way for more effective interventions. © 2024 Wiley Periodicals LLC.
Deciphering the landscape of triple negative breast cancer from microenvironment dynamics and molecular insights to biomarker analysis and therapeutic modalities
(John Wiley and Sons Inc, 2025) Harshita Tiwari; Swati Singh; Sonal Sharma; Priyamvada K. Gupta; Ashish Verma; Amrit Chattopadhaya; Brijesh Kumar; Sakshi Agarwal; Rajiv Kumar; Sanjeev Kumar Gupta; Vibhav Gautam
Triple negative breast cancer (TNBC) displays a notable challenge in clinical oncology due to its invasive nature which is attributed to the absence of progesterone receptor (PR), estrogen receptor (ER), and human epidermal growth factor receptor (HER-2). The heterogenous tumor microenvironment (TME) of TNBC is composed of diverse constituents that intricately interact to evade immune response and facilitate cancer progression and metastasis. Based on molecular gene expression, TNBC is classified into four molecular subtypes: basal-like (BL1 and BL2), luminal androgen receptor (LAR), immunomodulatory (IM), and mesenchymal. TNBC is an aggressive histological variant with adverse prognosis and poor therapeutic response. The lack of response in most of the TNBC patients could be attributed to the heterogeneity of the disease, highlighting the need for more effective treatments and reliable prognostic biomarkers. Targeting certain signaling pathways and their components has emerged as a promising therapeutic strategy for improving patient outcomes. In this review, we have summarized the interactions among various components of the dynamic TME in TNBC and discussed the classification of its molecular subtypes. Moreover, the purpose of this review is to compile and provide an overview of the most recent data about recently discovered novel TNBC biomarkers and targeted therapeutics that have proven successful in treating metastatic TNBC. The emergence of novel therapeutic strategies such as chemoimmunotherapy, chimeric antigen receptor (CAR)-T cells-based immunotherapy, phytometabolites-mediated natural therapy, photodynamic and photothermal approaches have made a significant positive impact and have paved the way for more effective interventions. © 2024 Wiley Periodicals LLC.
Development of ultra performance liquid chromatography tandem mass spectrometry method for simultaneous identification and quantitation of potential osteogenic phytochemicals in butea monosperma
(Oxford University Press, 2018) Vikas Bajpai; Awantika Singh; Pratibha Singh; Khushbu Sharma; Bikarma Singh; Bhim Pratap Singh; Mahendra Sahai; Rakesh Maurya; Brijesh Kumar
An ultra performance liquid chromatography coupled with hybrid triple-quadrupole linear ion trap tandem mass spectrometry (UPLC-ESI-QqQLIT-MS-MS) method in multiple reaction monitoring mode was developed for identification and simultaneous determination of potential osteogenic compounds in ethanol extracts of different plant parts of Butea monosperma collected from different geographical regions. The chromatographic separation was carried out on an Acquity UPLC CSH C18 column (1.7 μm, 2.1 × 100 mm) with 0.1% (v/v) formic acid in water and methanol as mobile phase under gradient conditions in 8 min. The developed method was validated according to the guidelines of international conference on harmonization. The correlation coefficients of all the calibration curves were ≥0.9995 and recoveries ranged from 95.2 to 105.8% (RSD ≤ 1.95%). Relative standard deviations of intra-day, inter-day precisions and stability were ≤1.74, 1.84 and 2.8%, respectively. The quantitative results showed remarkable differences in the content of all potential osteogenic compounds in different parts of the plant as well as samples from different geographical regions. Quantitative variations studied from principal component analysis indicated tentative markers for B. monosperma cultivars which can discriminate sample of different geographical regions. © The Author(s) 2018. Published by Oxford University Press. All rights reserved.
Evaluating Elastic Parameters of a CO2 Plume Using Model-Based and Sparse Layer Reflectivity Inversion of Time-Lapse Seismic Data: A Case Study
(John Wiley and Sons Inc, 2025) Gopal Hema; Satya Prakash Maurya; Nitin Verma; Ravi Kant; Ajay Pratap Singh; Brijesh Kumar; Raghav S. Singh; Kumar Hemant Singh
The objective of this research is to estimate the elastic properties of the CO2 plume in the Sleipner field and perform a comparative analysis of model-based inversion (MBI) and sparse layer reflectivity (SLR) inversion techniques. MBI is relatively old method, whereas SLR is relatively new method for seismic inversion. Model-based seismic inversion is a well-established deterministic inversion technique that iteratively minimizes the misfit between observed and modelled seismic data. In contrast, SLR inversion is designed to identify and analyse the reflectivity of thin subsurface layers by emphasizing sparsity in the reflectivity sequence. This study utilizes a set of time-lapse seismic angle stack data from the Sleipner field, comprising a 1994 pre-injection baseline and a 1999 post-injection monitor survey, following the injection of 2.35 million tons of CO2. These angle stacks were used to generate P-wave and S-wave reflectivity using the two-term Fatti amplitude versus offset (AVO) equation, which was then further utilized in the inversion process to estimate the elastic parameters. Acoustic and shear impedance (SI) were derived using MBI and SLR to evaluate their strengths, limitations, computational efficiency and adaptability to geological changes. In the CO2-injected zone, acoustic impedance values were observed between 2000 and 2400 m/s g/cm3, whereas SI values ranged from 100 to 400 m/s g/cm3. Our findings suggest that overall, MBI produces sharper and more reliable imaging across the entire seismic section. For P-impedance, MBI yielded correlation values of 0.980 with an error of 0.137 in 1994 and 0.989 with an error of 0.141 in 1999 datasets, whereas SLR showed higher correlation at the well location 0.997 with an error of 0.073 in 1994 and 0.998 with an error of 0.061 in 1999. For S-impedance, MBI achieved correlation values of 0.860 with an error of 0.650 in 1994 and 0.974 with an error of 0.265 in 1999 datasets. In comparison, SLR produced a correlation of 0.995 with an error of 0.072 in 1994 and 0.951 with an error of 0.370 in 1999 datasets at the well location. However, similar to the P-impedance case, whereas SLR performed well at the well location, its application to the full seismic volume resulted in reduced performance, characterized by noisier results and longer processing time. A comparative evaluation of MBI and SLR indicates that MBI offers greater efficiency, simpler implementation and faster computational performance. As a result, the impedance outputs obtained from MBI were subsequently converted into density, P-wave velocity and S-wave velocity using empirical relationships derived from well log data. In the seismic volumes, a significant change in the reservoir's elastic properties was observed in the CO2-saturated zone, compared to the Utsira Formation, which serves as the reservoir into which CO2 has been injected. Density decreased from 1.75 to 1.35 g/cm3 (∼23%), P-wave velocity from 2000 to 1820 m/s (∼9%) and S-wave velocity from 1150 to 638 m/s (∼45%). These changes reflect the effects of CO2 replacing brine in the pore space, leading to a reduction in bulk density and stiffness and indicating overall reservoir softening due to gas injection. Integrating these inversion methods with multi-parameter elastic estimation enables effective CO2 plume monitoring and reservoir characterization, highlighting the role of seismic inversion in detecting fluid-induced changes and supporting improved monitoring strategies in carbon capture and storage (CCS) operations. © 2025 European Association of Geoscientists & Engineers.
Exploring the utility of nonlinear hybrid optimization algorithms in seismic inversion: A comparative analysis
(Elsevier Ltd, 2024) Ravi Kant; Brijesh Kumar; S.P. Maurya; Raghav Singh; Anoop Kumar Tiwari
The present study integrates various local and global optimization techniques together to estimate subsurface properties from post-stack seismic data and compare their efficacy qualitatively and quantitatively. Specifically, a local gradient-based optimization method, the quasi-newton method (QNM), is combined with global techniques such as simulated annealing (SA), genetic algorithms (GA), and particle swarm optimization (PSO). These are well-established methods in geophysics. The research compares three global optimization methods (SA, GA, and PSO), their hybrid variants, and QNM for estimating subsurface acoustic impedance. The goal is to assess the trade-offs between solution accuracy and convergence efficiency, offering insights into the strengths and weaknesses of each approach. The objective is to guide the selection of the most effective optimization technique for seismic inversion, balancing quality and computational performance. Both synthetic and real seismic datasets are used to validate the proposed methodology, demonstrating its robust performance across various geological scenarios. Comparative analyses with single global inversion approaches reveal that hybrid optimization methods offer greater accuracy and reliability, positioning them as versatile tools for subsurface characterization. The results indicate that while the hybrid PSO method does not provide significant improvements over single PSO, it extends the convergence time. On the other hand, SA and GA perform adequately, but their hybrid versions considerably enhance solution quality at the cost of longer convergence times. Among the methods, SA shows the fastest convergence to the global solution, followed by GA and PSO. Hybrid SA stands out, delivering superior resolution and faster convergence compared to hybrid PSO and GA. © 2024
FOREWORD
(Bentham Science Publishers, 2025) Brijesh Kumar
[No abstract available]
Highly aqueous soluble CaF2:Ce/Tb nanocrystals: effect of surface functionalization on structural, optical band gap, and photoluminescence properties
(Springer New York LLC, 2016) Anees A. Ansari; Abdul K. Parchur; Brijesh Kumar; S.B. Rai
Abstract: The design of nanostructured materials with highly stable water-dispersion and luminescence efficiency is an important concern in nanotechnology and nanomedicine. In this paper, we described the synthesis and distinct surface modification on the morphological structure and optical (optical absorption, band gap energy, excitation, emission, decay time, etc.) properties of highly crystalline water-dispersible CaF2:Ce/Tb nanocrystals (core-nanocrystals). The epitaxial growth of inert CaF2 and silica shell, respectively, on their surface forming as CaF2:Ce/Tb@CaF2 (core/shell) and CaF2:Ce/Tb@CaF2@SiO2 (core/shell/SiO2) nanoarchitecture. X-ray diffraction and transmission electron microscope image shows that the nanocrystals were in irregular spherical phase, highly crystalline (~20 nm) with narrow size distribution. The core/shell nanocrystals confirm that the surface coating is responsible in the change of symmetrical nanostructure, which was determined from the band gap energy and luminescent properties. It was found that an inert inorganic shell formation effectively enhances the luminescence efficiency and silica shell makes the nanocrystals highly water-dispersible. In addition, Ce3+/Tb3+-co-doped CaF2 nanocrystals show efficient energy transfer from Ce3+ to Tb3+ ion and strong green luminescence of Tb3+ ion at 541 nm(5D4→7F5). Luminescence decay curves of core and core/shell nanocrystals were fitted using mono and biexponential equations, and R2 regression coefficient criteria were used to discriminate the goodness of the fitted model. The lifetime values for the core/shell nanocrystals are higher than core-nanocrystals. Considering the high stable water-dispersion and intensive luminescence emission in the visible region, these luminescent core/shell nanocrystals could be potential candidates for luminescent bio-imaging, optical bio-probe, displays, staining, and multianalyte optical sensing. Graphical Abstract: A newly designed CaF2:Ce/Tb nanoparticles via metal complex decomposition rout shows high dispersibility in aqueous solvents with enhanced photoluminescence. The epitaxial growth of inert CaF2 shell and further amorphous silica, respectively, enhanced their optical and luminescence properties, which is highly usable for luminescent biolabeling, and optical bioprobe etc.[InlineMediaObject not available: see fulltext.] © 2016, Springer Science+Business Media New York.
Identification of the reservoir using seismic inversion based on particle swarm optimization method: A case study
(Springer, 2024) Ravi Kant; Brijesh Kumar; S.P. Maurya; Nitin Verma; Ajay P Singh; G. Hema; Raghav Singh; K.H. Singh; Piyush Sarkar
Accurate reservoir characterization is a crucial step for developing, managing, and optimizing hydrocarbon production. In this current study, we employ particle swarm optimization techniques (PSO) to perform an inversion of post-stack seismic data, extracting information about subsurface acoustic impedance and porosity. Conventional seismic inversion methods predominantly employ local optimization strategies, which often rely on the availability of initial models, particularly in unfamiliar geological settings. In contrast, our approach is based on global search principles, consistently striving to converge towards a global optimal solution, independent of the initial model. To validate the developed technique, we initially subjected it to synthetic data and a wedge model, followed by its application to real data from the Blackfoot field in Canada. The investigation reveals that the inverted results, both for the synthetic and real data, closely align with the observed data. Statistical analysis indicates a high correlation of 0.99 for the synthetic data. For the real data, the correlation remains strong at 0.89. Finally, the PSO-based inversion algorithm is applied across the entire seismic volume, successfully yielding high-resolution subsurface information. This inversion reveals impedance variations ranging from 6500 to 13000 m/s*g/cc, with porosity levels spanning 5–24%, within the Blackfoot region. As per the findings of the investigation, it is evident that the upper section of the subsurface mainly comprises non-solid rock materials. The examination of inverted sections has disclosed an atypical region characterized by low impedance (<9000 m/s*g/cc) and remarkably high porosity (>18%) within the time interval of 1040–1060 ms two-way travel time. This distinctive zone is corroborated by well-log analysis at the same depth and is categorized as a reservoir. © Indian Academy of Sciences 2024.
Investigation of optical properties and energy transfer in Eu(III) and Tb(III) based composite compound dispersed in polar, non-polar solvents and polymer matrix
(Institute of Physics Publishing, 2019) Praveen Kumar Shahi; Brijesh Kumar; Rajiv Prakash; Shyam Bahadur Rai
Acomposite compound (CC) has been developed by the physical mixing of two coordination compounds(1,10-Phenanthroline)tris[4,4,4-trifluoro-1-(2-thienyl)-1,3butanedionato]europium (III) [abbreviated as Eu(TTA)3Phen or ETP] and (1,10-Phenanthroline)tris[2-acetoxybenzoate] terbium(III) [abbreviated Tb(ASA)3Phen or TAP]. Strong photo-physical properties ofCChave been used for its study in different liquid medium and in PVA polymer matrix also. The studies of optical as well as structural properties of composite material have been carried out to observe the nature of interaction, energy transfer and migration of energies. The Fourier Transform Infrared (FTIR) spectra ofCCshow no new bond formation at atomic level and hence both ETP and TAP are entangled to each other by weak interacting forces. The photoluminescence (PL) emission of the Eu3+ ions enhance while of the Tb3+ ions decreases in the CC, indicating migration of energy from Tb3+ to Eu3+ ion. The effect of medium on the optical properties of this composite material has been investigated in detail. The excitation, emission as well as decay profiles of the composite material has been carried out in polar (ethanol), non-polar (Chloroform) as well as in polymer matrix {Poly-vinyl alcohol (PVA) matrix}. The reason behind the different shape and intensity in excitation and emission spectra of the composite material in different medium has been discussed. That concludes maximum fluorescence intensity in PVA matrix and least in polar solvents. In last stage, the plasmonic silver nanoparticles (AgNPs) have been introduced to further enhance the emission intensity in PVA matrix. © 2019 IOP Publishing Ltd.
Investigations of spherical Cu NPs in sodium lauryl sulphate with Tb3+ ions dispersed in PVA films
(Elsevier Ltd, 2016) Brijesh Kumar; Gagandeep Kaur; S.B. Rai
Cu nanoparticles (NPs) have been prepared in SDS solution using 1064 nm laser radiation at different fluence 37 J/cm2, 64 J/cm2 and 88 J/cm2 and structurally characterized. The TEM measurements reveal the presence of nanoparticles of spherical shape with different size. The size of the nanoparticles and their concentration increases with the increase of fluence.The effect of these Cu nanoparticles on the emissive properties of Tb3+ ion in polymer films has been studied. It is found that emission intensity of Tb3+ first increases and then deceases both with concentration of Cu NPs as well as with sizes. The PL intensity of Tb3+ ions is minimum for Cu NPs prepared with highest fluence. It has been explained in term of local field effect. This was also verified by life time measurements. These thin PVA films of copper nanoparticles displayed a highly temperature-dependent electrical conductivity with sensitivity at least comparable to commercial materials which suggest the use of these copper NPs embedded PVA films as novel, low-cost sensor materials. © 2015 Elsevier Ltd.
Investigations on electrical and magnetic properties of Fe2O3 nanoparticles dispersed in polymer film with terbium ion
(American Scientific Publishers, 2015) Brijesh Kumar; Gagandeep Kaur; R.K. Kotnala; S.B. Rai
Spherical Fe2O3 nanoparticles (NPs) with average particle size 30–70 nm have been prepared by laser ablation method in distilled water by applying 1064 nm laser line from Nd:YAG laser and were used for the fabrication of PVA films with and without Tb ion. The frequency and temperature dependent electrical conductivity of PVA polymer film have been measured in presence of Tb ions with Fe2O3 NPs for frequency range between 20 Hz to 1 MHz and temperature range 308–348 K. It has been found that electrical conductivity of the films is enhanced in presence of Fe2O3 NPs and Tb ion. Magnetization (M–H) loop revealed PVA as diamagnetic with very small magnetic moment −0.0015 emu/g converted to ferromagnetic in presence of Fe2O3 nanoparticles and paramagnetic in presence of Tb ion with saturation magnetization of 0.004 emu/g and 0.07 emu/g respectively. It maintains its paramagnetic character in presence of both Fe2O3 NPs and Tb ions with saturation magnetization 0.03 emu/g. © 2015 American Scientific Publishers. All rights reserved.