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Up-conversion photoluminescence and thermoluminescence studies of Er3+ doped Y2O3 phosphors

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Optoelectronics Letters 2024年

作者： Dhaleshwari Fekar Prachi P.Nimje ravi shrivastava Siteshwari Chandrakar Department of Chemistry Shri Shankaracharya Professional University Department of Physics Shri Shankaracharya Professional University Department of Physics， Govt.VYT PG Autonomous College

This article reports the preparation of Yttrium Aluminate (Y2O3) doped with various concentrations of Er3+using high temperature synthesis method. Photoluminescence Emission spectra of the samples were recorded at an excitation of 980 nm laser source. Two prominent peaks centered at 484 and 574 nm were found and attributed the2P3/2→4I11/2and4S3/2→4I15/2respectively. The sample with 2.5 mol% of Er3+provided the optimum intensity in emission spectra. The sample with optimum PL emission was investigated for its Thermoluminescence glow curve exhibited Second order kinetics. The peak TL intensity was found around 236℃ i.e. towards high temperature which supports the fact of formation of deeper traps， therefore， the material taken may be regarded as a good candidate for LED applications.

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Judd-Ofelt analysis of Dy3+ doped Ca2MgSi2O7 phosphors resulting in white light emission

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Optoelectronics Letters 2024年

作者： ravi shrivastava Nandita M.Prassanno Prachi P.Nimje Siteshwari Chandrakar Shri Shankaracharya Professional University Government VYT PG Autonomous College

Di-Calcium Magnesium Silicate (Ca2MgSi2O7) doped with various concentrations （1.0， 2.0， 2.5 and 3.0 mol%） of Dysprosium （III） was prepared using a high-temperature technique named as solid state reaction method. The sample with 2.5 mol% of Dysprosium （III） underwent X-ray diffraction （XRD） characterization to confirm the proper phase formation in the sample. Observed XRD pattern matched significantly with Crystallographic Open Database （Card No. 96-210-6180） with a significantly high Figure of Merit （0.84）. Photoluminescence （PL） excitation and emission spectra were also recorded. PL excitation spectrum of Di-Calcium Magnesium Silicate doped with 2.5 mol% of Dysprosium （III） exhibited a most prominent peak at 395 nm， therefore， the emission spectra of the samples were monitored at 395 nm excitation. The emission spectra exhibited prominent peaks centred at 483 nm （Blue）， 577 nm （Yellow）， and 664 nm （Orange Red） due to the transitions4F9/2→6H15/2，4F9/2→6H13/2， and4F9/2→6H11/2respectively. The colour Chromaticity Diagram （CIE） of this emission spectra was found at （0.304， 0.340） which lies in the white light region. Keeping the objective to evaluate the emitted white light for its suitability in LED application， colour Rendering Index （CRI） and colour Correlated Temperature （CCT） were also calculated. Radiation life time was estimated using Judd-Ofelt analysis.

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TL Glow Curve Study, Kinetics, PL and XRD Analysis of Mn2+Doped CaAl2O4Phosphors

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Journal of Minerals and Materials Characterization and Engineering 2012年第11期11卷 1081-1084页

作者： Jagjeet Kaur Nemana Subramanyam Suryanarayana Beena Jaykumar Vikas Dubey ravi shrivastava Huma Nazli Baig Department of Physics Vishwanath Yadav Tamaskar Post Graduate Autonomous College Durg India

The present paper reports Thermoluminescence (TL) Glow curve of Mn2+ doped CaAl2O4 phosphor with different UV exposure time. The Glow peak shows general order kinetics and evaluation of kinetic parameters was done by peak shape method. Calculations of Trap Depth were done with Chen’s different methods and order of kinetics, activation energy and frequency factor are calculated. The recorded glow curve shifts towards higher temperature with increasing intensity as a function of UV exposure time until 30 minutes where it is seen that the peak shifts towards low temperature side and intensity also decreases. The peaks were found at 345?C, 356.83?C, 358?C and 356.73?C respectively using the heating rate 6.7?C/s. The PL (photoluminescence) excitation spectra show peaks at 248 nm and 362 nm whereas emission spectra shows peaks between 364 nm and 551 nm. Sample was characterized by XRD technique.

关键词： Phosphors Photoluminescence Thermoluminescence Kinetic Parameters Trap Depth

Optimizing bone marrow harvesting sites for enhanced mesenchymal stem cell yield and efficacy in knee osteoarthritis treatment

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World Journal of Methodology 2025年第2期15卷 92-107页

作者： Arulkumar Nallakumarasamy Sandeep shrivastava ravi Velamoor Rangarajan Naveen Jeyaraman Avinash Gandi Devadas Swaminathan Ramasubramanian Madhan Jeyaraman Department of Orthopaedics Datta Meghe Institute of Higher Education and ResearchWardha 442004MaharashtraIndia Department of Regenerative Medicine Mother Cell Regenerative CentreTiruchirappalli 620017Tamil NaduIndia Department of Orthopaedics Government Medical CollegeOmandurar Government EstateChennai 600002Tamil NaduIndia Department of Orthopaedics ACS Medical College and HospitalDr MGR Educational and Research InstituteChennai 600077Tamil NaduIndia

Knee osteoarthritis(OA)is a debilitating condition with limited long-term treatment *** therapeutic potential of mesenchymal stem cells(MSCs),particularly those derived from bone marrow aspirate concentrate,has garnered attention for cartilage repair in *** the iliac crest is the traditional site for bone marrow harvesting(BMH),associated morbidity has prompted the exploration of alternative sites such as the proximal tibia,distal femur,and proximal *** paper reviews the impact of different harvesting sites on mesenchymal stem cell(MSC)yield,viability,and regenerative potential,emphasizing their relevance in knee OA *** iliac crest consistently offers the highest MSC yield,but alternative sites within the surgical field of knee procedures offer comparable MSC characteristics with reduced *** integration of harvesting techniques into existing knee surgeries,such as total knee arthroplasty,provides a less invasive approach while maintaining thera-peutic ***,variability in MSC yield from these alternative sites underscores the need for further research to standardize techniques and optimize clinical *** directions include large-scale comparative studies,advanced characterization of MSCs,and the development of personalized harvesting ***,the findings suggest that optimizing the site of BMH can significantly influence the quality of MSC-based therapies for knee OA,enhancing their clinical utility and patient outcomes.

关键词： Knee Osteoarthritis Mesenchymal stem cells Bone marrow harvest Regenerative medicine

Understanding and controlling the variables for stromal vascular fraction therapy

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World Journal of Stem Cells 2024年第8期16卷 784-798页

作者： Naveen Jeyaraman Sandeep shrivastava VR ravi Arulkumar Nallakumarasamy Aditya Pundkar Madhan Jeyaraman Department of Orthopaedics Datta Meghe Institute of Higher Education and ResearchWardha 442004MaharashtraIndia Regenerative Medicine Mother Cell Regenerative CentreTiruchirappalli 620017Tamil NaduIndia Department of Orthopaedics Jawaharlal Nehru Medical CollegeDatta Meghe Institute of Higher Education and ResearchWardha 442004MaharashtraIndia Department of Orthopaedics ACS Medical College and HospitalDr MGR Educational and Research InstituteChennai 600077Tamil NaduIndia

In regenerative medicine,the isolation of mesenchymal stromal cells(MSCs)from the adipose tissue’s stromal vascular fraction(SVF)is a critical area of *** review meticulously examines the isolation process of MSCs,starting with the extraction of adipose *** choice of liposuction technique,anatomical site,and immediate processing are essential to maintain cell *** delve into the intricacies of enzymatic digestion,emphasizing the fine-tuning of enzyme concentrations to maximize cell yield while preventing *** review then outlines the filtration and centrifugation techniques necessary for isolating a purified SVF,alongside cell viability assessments like flow cytometry,which are vital for confirming the efficacy of the isolated *** discuss the advantages and drawbacks of using autologous vs allogeneic SVF sources,touching upon immunocompatibility and logistical considerations,as well as the variability inherent in donor-derived *** choices,the selection between hypo-dermic needles vs liposuction cannulas,and the role of adipose tissue lysers in achieving cellular dissociation are evaluated for their impact on SVF *** protocols are also analyzed for their part in ensuring the integrity of the *** necessity for standardized MSC isolation protocols is highlighted,promoting reproducibility and successful clinical *** encourage ongoing research to deepen the understanding of MSC biology and therapeutic action,aiming to further the field of regenerative *** review concludes with a call for rigorous research,interdisciplinary collaboration,and strict adherence to ethical and regulatory standards to safeguard patient safety and optimize treatment outcomes with MSCs.

关键词： Mesenchymal stromal cells Stromal vascular fraction Adipose tissue Autologous stromal vascular fraction Stromal vascular fraction isolation

Assessment of bone condition by acoustic emission technique: A review

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Journal of Biomedical Science and Engineering 2009年第3期2卷 144-154页

作者： Sharad shrivastava ravi Prakash Birla Institute of Technology and Science Pilani India.

The paper deals with the review of acoustic emission technique in biomedical field. The re-view is done with the aim to provide an overview of the use of AE technique in biomedical field, mainly concentrated on the AE behavior of bone under different loading conditions, its depend-ence on strain rate, in osteoporosis, monitoring the fracture healing process of bone. The over-all conclusion from the review was that almost all the studies in bone indicated that the initial AE occurs only in the plastic region and just prior to yield. That means the use of AE tech-nique for clinical application cannot be consid-ered as a safe technique, but the early occur-rence of AE events from callus promises the application of AE technique for monitoring the fracture healing process. The negligible effect of soft tissues on AE response of bone prom-ises AE to become a non-invasive method for assessment of bone condition.

关键词： Acoustic Emission Assessment Strain Rate Callus Fracture Healing Osteoporosi