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synthesis and enhanced photoluminescence properties of red emitting divalent ion(Ca^(2+))doped Eu:Y_(2)O_(3)nanophosphors for optoelectronic applications

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Journal of Rare Earths 2022年第8期40卷 1187-1198页

作者： Arpita Dwivedi Monika srivastava Ankur Dwivedi Amit srivastava Anurag Mishra s.k.srivastava Department of Physics Institute of ScienceBanaras Hindu University(BHU)Varanasi221005India school of Materials science and Technology Indian Institute of Technology(BHU)Varanasi221005India Department of Mining Engineering Indian Institute of Technology(BHU)Varanasi221005India Department of Physics TDPG College VBS Purvanchal UniversityJaunpur222001India

This work presents the synthesis of Y_(2)O_(3):Eu^(3+),χCa^(2+)(χ=0 mol%,1 mol%,3 mol%,5 mol%,7 mol%,9 mol%,11 mol%)nanophosphors with enhanced photoluminescence properties through a facile solution combustion method for optoelectronic,display,and lighting *** X-ray diffraction(XRD)patterns of the proposed nanophosphor reveal its structural properties and crystalline *** transmission electron microscope(TEM)results confirm the change in the shape of the particle and aggregation of particles after co-doping with Ca^(2+).Fourier transform infrared spectroscopy(FTIR)and Raman vibrations also confirm the presence of Y-O vibration and subsequently explain the crystalline nature,structural properties,and purity of the *** the synthesized nanophosphors samples emit intense red emission at 613 nm(~5D_(0)→~7 F_(2))under excitation with 235,394 and 466 nm wavelengths of Eu^(3+)*** photoluminescence(PL)emission spectra excited with 235 nm illustrate the highest emission peak with two other emission peaks excited with 466 and 394 nm that is 1.4 times higher than 466 nm and 1.9 times enhanced by 394 nm wavelength,*** emission intensity of Y_(2)O_(3):Eu^(3+),χCa^(2+)(5 mol%)is increased 8-fold as compared to Eu:Y_(2)O_(3).Doping with Ca^(2+)ions enhances the emission intensity of Eu:Y_(2)O_(3)nanopho sphors due to an increase in energy transfer in Ca^(2+)→Eu^(3+)through asymmetry in the crystal field and by introduction of radiative defect centers through oxygen vacancies in the yttria *** is also observed that the optical band gap and the lifetime of the~5D_(0)level of Eu^(3+)ions in Y_(2)O_(3):Eu^(3+),xCa^(2+)nanophosphor sample gets changed with a doping conce ntration of Ca^(2+)*** also reveals high thermal stability and quantum yield as estimating activation energy of 0.25 eV and 81%,***,CCT,and color purity values(>98%)show an improved red-emitting nanophosphor in the warm region of light,which m

关键词： Red emission Photoluminescence(PL) Y_(2)O_(3):Eu^(3+),xCa^(2+) Rare earths Nanophosphors LEDs

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A near infrared optical reflector using one-dimensional photonic crystal structure containing chalcogenide glasses

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Optoelectronics Letters 2010年第6期6卷 406-411页

作者： sanjeev k.srivastava s k Awasthi s k srivastava s.P.Ojha Department of Physics Amity Institute of Applied SciencesAmity University Department of Physics Jaypee Institute of Information TechnologyDeemed University Department of Physics Mahila Maha VidyalayBanaras Hindu University Department of Applied Physics Institute of TechnologyBanaras Hindu University

The reflectivity of one-dimensional chalcogenide photonic crystal(CGPC) structure with the first order reflection band in near infrared(NIR) region is theoretically ***-se and Ge-s chalcogenide glasses are used as high and low refractive index layers respectively,because these materials have zero absorption in NIR *** transfer matrix method(TMM) is employed to calculate the reflective spectra of the proposed *** theoretical results of reflective spectra of bulk chalcogenide materials with the composition of sb40se60 and Ge30s70 for 4,8,12 and 15 layers and thicknesses of 117 nm and 183 nm respectively,at normal incidence,are close agreement with the experimental ***,by increasing the number of layers of sb40se60 and Ge30s70,the reflection bands can be enhanced in the wider range of the NIR region for the polarization at different angles and thus the broadband omnidirectional reflector can be designed.

关键词：一维光子晶体晶体结构硫系玻璃近红外光反射镜红外区域反射光谱计算结果

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Effect of hydrogen plasma treatment on the growth and microstructures of multiwalled carbon nanotubes

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Nano-Micro Letters 2010年第1期2卷 42-48页

作者： s.k.srivastava V.D.Vankar V.kumar Department of Physics Indian Institute of Technology Delhi National Physical Laboratory Dr.K.S.Krishnan Marg

The effect of hydrogen plasma treatment of iron oxide films on the growth and microstructure of carbon nanotubes(CNTs)by microwave plasma enhanced chemical vapor deposition process has been *** plasma was characterized in-situ using optical emission *** of the films was examined by scanning electron *** analysis was carried out by high resolution transmission electron microscopy(HRTEM)equipped with energy dispersive X-ray spectroscopy(EDs)and micro-diffraction *** is found that oxide films without H_2 plasma pretreatment or treated for lesser time resulted in CNT films with high percentage of carbonaceous particles and with embedded particles/nanorods distributed discontinuously in the cavity of the *** embedded particles were found to be of iron carbide(Fe-C)as confirmed by HRTEM,EDs and micro-diffraction *** observations suggested that the iron oxide particles had poor catalytic action for CNT growth and in-situ reduction of oxide clusters to Fe by hydrogen plasma plays a key role in discontinuous filling of the nanotubes by the catalytic particles.

关键词： Carbon nanotubes Chemical vapor deposition Iron carbide MPECVD

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Fuzzy Logic Based Power Flow Control Analysis of Advanced Unified Power Flow Controller

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Journal of Energy and Power Engineering 2011年第3期5卷 252-259页

作者： s.k. srivastava s.N. singh Department of Electrical Engineering MMM Engineering College Gorakhpur-273010 India Department of Electrical Engineering Indian Institute of Technology Kanpur-208016 India

Due to rapidly development of high power semiconductor devices with fast control features have made possible to control the power flow more efficiently and effectively. The Flexible AC Transmission systems （FACTs） in this category introduces several innovative operating control devices. One of the recent devices is Advanced Unified Power Flow Controller （AUPFC） or multi-converter UPFC, which can control bus voltage and real and reactive power flows of more than one line or even a sub-network. This paper presents performance analysis of AUPFC based on d-q axis model theory. Based on the analysis, a new fuzzy logic rules based control algorithm has been developed in this paper which improves the system performance. The control rules are structured depending upon the relationship between series inserted voltages in multi-line and the desired changes of real and reactive power flows in the control network. The impacts of different controllers along with parameters of series connected transformers and transmission lines have been investigated through developed control block models in sIMULINk. The effectiveness of the proposed scheme is demonstrated by a case study.

关键词： FACTs AUPFC multi-converter UPFC fuzzy-PI controller sIMULINk FLC.

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ANN Based Performance Analysis of UPFC in Power Flow Control

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Journal of Energy and Power Engineering 2010年第8期4卷 40-47页

作者： s.k. srivastava s.N. singh Department of Electrical Engineering MMM Engineering College Gorakhpur 273010 India Department of Electrical Engineering Indian Institute of Technology Kanpur 208016 India

The Unified Power Flow Controller （UPFC） is one of the most versatile Flexible AC Transmission systems （FACTs） devices that has unique capability of independently controlling the real and reactive power flows, in addition to regulate the system bus voltage. This paper presents performance analysis of Unified Power Flow Controller based on two axis theory. Based on this analysis, a new Artificial Neural Network （ANN） based controller has been proposed to improve the system performance. The controller rules are structured depending upon the relationship between series inserted voltage and the desired changes in real/reactive power flow in the power system. The effects of different controllers along with parameters of series transformer and transmission line have been investigated through developed control block model in sIMULINk tool box of MATLAB. The effectiveness of the proposed scheme is demonstrated by case studies.

关键词： FACTs UPFC ANN neural controller sIMULINk.

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Impact of infectious density-induced additional screening and treatment saturation on COVID-19:Modeling and cost-effective optimal control

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Infectious Disease Modelling 2024年第2期9卷 569-600页

作者： sonu Lamba Tanuja Das Prashant k.srivastava Department of Mathematics Indian Institute of Technology Patna Bihta–801106PatnaBiharIndia Department of Mathematics and statistics University of New Brunswick FrederictonNBE3B 5A3Canada

This study introduces a novel sI2HR model,where“I2”denotes two infectious classes representing asymptomatic and symptomatic infections,aiming to investigate and analyze the cost-effective optimal control measures for managing *** model incorporates a novel concept of infectious density-induced additional screening(IDIAs)and accounts for treatment ***,the model considers the possibility of reinfection and the loss of immunity in individuals who have previously *** validate and calibrate the proposed model,real data from November–December 2022 in Hong kong are *** estimated parameters obtained from this calibration process are valuable for prediction purposes and facilitate further numerical *** analysis of the model reveals that delays in screening,treatment,and quarantine contribute to an increase in the basic reproduction number R0,indicating a tendency towards *** particular,from the elasticity of R0,we deduce that normalized sensitivity indices of baseline screening rate(θ),quarantine rates(γ,αs),and treatment rate(α)are negative,which shows that delaying any of these may cause huge surge in R0,ultimately increases the disease ***,by the contour plots,we note the two-parameter behavior of the infectives(both symptomatic and asymptomatic).Expanding upon the model analysis,an optimal control problem(OCP)is formulated,incorporating three control measures:precautionary interventions,boosted IDIAs,and boosted *** Pontryagin's maximum principle and the forward-backward sweep method are employed to solve the *** numerical simulations highlight that enhanced screening and treatment,coupled with preventive interventions,can effectively contribute to sustainable disease ***,the cost-effectiveness analysis(CEA)conducted in this study suggests that boosting IDIAs alone is the most economically efficient and cost-effective approach compared to other *** CEA resul

关键词： COVID-19 IDIAs Estimation Prediction Optimal control Cost-effectiveness analysis

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Flavonoid Myricetin as Potent Anticancer Agent: A Possibility towards Development of Potential Anticancer Nutraceuticals

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Chinese Journal of Integrative Medicine 2024年第1期30卷 75-84页

作者： Anchal Trivedi Adria Hasan Rumana Ahmad sahabjada siddiqui Aditi srivastava Aparna Misra snober s.Mir Department of Biochemistry Era's Lucknow Medical College&HospitalEra UniversityLucknow(226003)India Molecular Cell Biology Laboratory Integral Information and Research Centre-4(IIRC-4)Department of BioengineeringFaculty of EngineeringIntegral UniversityLucknow(226026)India Department of Biotechnology Era's Lucknow Medical College&HospitalEra UniversityLucknow(226003)India Department of Biosciences Faculty of ScienceIntegral UniversityLucknow(226026)India

Good nutrition plays a crucial role in maintaining a balanced lifestyle. The beneficial effects of nutrition have been found to counteract nutritional disturbances with the expanded use of nutraceuticals to treat and manage cardiovascular diseases, cancer, and other developmental defects over the last decade. Flavonoids are found abundantly in plant-derived foods such as fruits, vegetables, tea, cocoa, and wine. Fruits and vegetables contain phytochemicals like flavonoids, phenolics, alkaloids, saponins, and terpenoids. Flavonoids can act as anti-inflammatory, anti-allergic, anti-microbial(antibacterial, antifungal, and antiviral) antioxidant, anti-cancer, and anti-diarrheal agents. Flavonoids are also reported to upregulate apoptotic activity in several cancers such as hepatic, pancreatic, breast, esophageal, and colon. Myricetin is a flavonol which is naturally present in fruits and vegetables and has shown possible nutraceutical value. Myricetin has been portrayed as a potent nutraceutical that may protect against cancer. The focus of the present review is to present an updated account of studies demonstrating the anticancer potential of myricetin and the molecular mechanisms involved therein. A better understanding of the molecular mechanism(s) underlying its anticancer activity would eventually help in its development as a novel anticancer nutraceutical having minimal side effects.

关键词： myricetin flavonoids anticancer nutraceuticals Chinese medicine Ayurveda complementary and alternative medicine

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