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Prabhakar A, Shah P, Gautham U, Natarajan V, Ramesh V, Chandrachoodan N, Tayur S. Optimization with photonic wave-based annealers. Philos Trans A Math Phys Eng Sci 2023; 381:20210409. [PMID: 36463927 DOI: 10.1098/rsta.2021.0409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Accepted: 08/14/2022] [Indexed: 06/17/2023]
Abstract
Many NP-hard combinatorial optimization (CO) problems can be cast as a quadratic unconstrained binary optimization model, which maps naturally to an Ising model. The final spin configuration in the Ising model can adiabatically arrive at a solution to a Hamiltonian, given a known set of interactions between spins. We enhance two photonic Ising machines (PIMs) and compare their performance against classical (Gurobi) and quantum (D-Wave) solvers. The temporal multiplexed coherent Ising machine (TMCIM) uses the bistable response of an electro-optic modulator to mimic the spin up and down states. We compare TMCIM performance on Max-cut problems. A spatial photonic Ising machine (SPIM) convolves the wavefront of a coherent laser beam with the pixel distribution of a spatial light modulator to adiabatically achieve a minimum energy configuration, and solve a number partitioning problem (NPP). Our computational results on Max-cut indicate that classical solvers are still a better choice, while our NPP results show that SPIM is better as the problem size increases. In both cases, connectivity in Ising hardware is crucial for performance. Our results also highlight the importance of better understanding which CO problems are most likely to benefit from which type of PIM. This article is part of the theme issue 'Quantum annealing and computation: challenges and perspectives'.
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Affiliation(s)
- A Prabhakar
- Indian Institute of Technology Madras, Chennai 600036, India
| | - P Shah
- Indian Institute of Technology Madras, Chennai 600036, India
| | - U Gautham
- Indian Institute of Technology Madras, Chennai 600036, India
| | - V Natarajan
- Indian Institute of Technology Madras, Chennai 600036, India
| | - V Ramesh
- Indian Institute of Technology Madras, Chennai 600036, India
| | | | - S Tayur
- Carnegie Mellon University, Pittsburgh, PA 15213, USA
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Santhana Marichamy V, Natarajan V. Efficient big data security analysis on HDFS based on combination of clustering and data perturbation algorithm using health care database. IFS 2022. [DOI: 10.3233/jifs-213024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
In this manuscript proposes an efficient big data security analysis on HDFS based on the combination of Improved Deep K-means Clustering (IDFKM) algorithm and Modified 3D rotation data perturbation algorithm using health care database. To compile a similar group of data, an Improved Deep K-means Clustering (IDFKM) Algorithm is used as partitioning the medical data. After clustering, Modified 3D rotation data perturbation technique is used to satisfy the privacy requirement of the client. Modified 3D rotation Data Perturbation technique perturbs each and every sensitive data of the cluster and all the key parameters values used for clustering have warehoused in the database file sector. The proposed approach is executed by Java program, its efficiency is assessed by Health care database. The metrics under the study of memory usage attains higher accuracy 34.765%, 23.44%, 52.74%, 18.74%, lower execution time 35.23%, 23.76%, 27.86%, 27.76%, higher Efficiency 26.85%, 38.97%, 28.97%, 35.65%. then the proposed method is compared with the existing methods such asSecurity Analysis of SDN Applications for Big Data with spoofing identity, Tampering with data, Repudiation threats, Information disclosure, Denial of service and Elevation of privileges (STRIDE), Big Data Analysis-based Secure Cluster Management for using Ant Colony Optimization (ACA) Optimized Control Plane in Software-Defined Networks, System Architecture for Secure Authentication and Data Sharing in Cloud Enabled Big Data Environment using LemperlZivMarkow Algorithm (LZMA) and Density-based Clustering of Applications with Noise (DBSCAN), Big Data Based Security Analytics using data based security analytics (BDSA) approach for Protecting Virtualized Infrastructures in Cloud Computing respectively.
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Affiliation(s)
- V. Santhana Marichamy
- Department of Computer Science and Engineering, SRM Valliammai Engineering College, SRM Nagar, Kattankulathur, Tamil Nadu, India
| | - V. Natarajan
- Department of Instrumentation Engineering, Madras Institute of Technology, Anna University, Chennai, India
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Chockalingam P, Natarajan V, Sekar T, Rajaram A, Yusuf MM, Gunasekaran S, Nayar PG, Chockalingam V. Effectiveness of a home-based cardiovascular disease prevention program during the COVID-19 pandemic. Eur Heart J 2022. [PMCID: PMC9383402 DOI: 10.1093/eurheartj/ehab849.156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Funding Acknowledgements Type of funding sources: None. Background Home-based cardiovascular disease (CVD) primary prevention (HBPP) and cardiac rehabilitation (HBCR) programs which occupied a small proportion of the overall Preventive Cardiology work in the past have become mainstream during the COVID-19 pandemic. Purpose This study aims to analyse the effectiveness of a home-based CVD prevention program implemented during the pandemic in India. Methods A retrospective study was conducted on pre-pandemic and pandemic enrolees. Health behaviour, CVD risk factors, physical and mental component score (PCS, MCS) from SF-12 questionnaire, body mass index (BMI), 6-minute walk distance (6MWD), and clinical and biochemical parameters were assessed. A multidisciplinary team consisting of Physician, Physiotherapist, Dietician and Counselling Psychologist provided the program using tele-health platforms. Results Of the 66 subjects (55 ± 13 years, 73% male), 17 (26%) enrolled pre-pandemic and 49 (74%) enrolled during-pandemic, 28 (42%) were HBPP and 38 (58%) were HBCR participants. Majority of the subjects (n = 51, 77%), with significantly more HBCR than HBPP participants, harboured 4 or more risk factors (p = 0.04). In the 60 (91%) program completers, BMI, 6MWD, PCS and MCS had improved significantly. SBP, DBP, LVEF, HbA1c, total cholesterol and LDL had improved significantly in affected subjects. Completely home-based participants (n = 44, 67%) who never had any in-person contact with the team during the program also showed significant improvement. No adverse events were reported. Conclusion Comprehensive home-based CVD prevention programs are effective in improving anthropometric, clinical, biochemical and psychosocial parameters, are a safe alternative to conventional programs and could potentially become the standard-of-care in the post-pandemic era.
Abstract Figure. Outcomes in program participants
Abstract Figure. Management of ACS in participants ![]()
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Affiliation(s)
| | | | - T Sekar
- Cardiac Wellness Institute, Chennai, India
| | | | - M M Yusuf
- Apollo Main Hospitals, Chennai, India
| | | | - P G Nayar
- Malar Fortis Hospital , Chennai, India
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Chockalingam P, Natarajan V, Sekar T. A survey-based comparison of cardiovascular health risk behaviours in Indian men and women during the pandemic. Eur Heart J 2022. [DOI: 10.1093/eurheartj/ehab849.147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
Funding Acknowledgements
Type of funding sources: None.
Background
Cardiovascular disease (CVD), the leading cause of mortality globally, is caused by a combination of behavioral, clinical and genetic risk factors. The rising prevalence of unhealthy diet, inadequate exercise, psychosocial factors and tobacco use in urban and rural populations of India has posed a major epidemiological and healthcare threat in the recent past.
Purpose
This study aims to understand the cardiovascular health risk behaviors in Indian men and women during the pandemic.
Methods
A survey-based study was conducted at different time points between April 2020 and August 2021. A pre-tested anonymized self-administered questionnaire was distributed online as a pre-program assessment of participants registering for the health awareness webinars conducted by our team. Demographic data and CVD risk behaviors pertaining to dietary consumption, exercise routine, sedentary behavior, psychosocial factors, sleep pattern, tobacco use and alcohol consumption were collected. Not meeting daily intake of whole grains and at least 4 portions of vegetables and fruits, non-performance of at least 150 minutes of brisk aerobic exercise per week, chronic stress and use of tobacco were considered risky behaviors, as per the international guidelines.
Results
Of the 573 subjects, 305 (53%) were women and 236 (41%) were 15-30 years old. Majority of subjects were not meeting their requirements pertaining to whole grains (76%) and fruits/vegetables (72%). Inadequate exercise (48%), chronic stress (31%) and tobacco use (5%) were noted. Significantly more women than men (p = 0.0001) were falling short in their exercise requirement. Significantly more men than women (p = 0.0001) were using tobacco products (Figure).
Conclusion
Cardiovascular risk behaviors are highly prevalent in Indian men and women during the pandemic calling for a coordinated effort to increase awareness and modify to a healthy behavior. Abstract Figure. Risk behaviors in study subjects Abstract Figure. Comparison of risk behaviors
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Affiliation(s)
| | | | - T Sekar
- Cardiac Wellness Institute, Chennai, India
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Senthilkumar K, Kanagathara N, Ragavendran V, Natarajan V, Marchewka M. Quantum chemical computational studies of 1,3-diammonium propylarsenate: a semi organic crystalline salt. INORG NANO-MET CHEM 2021. [DOI: 10.1080/24701556.2021.1963282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- K. Senthilkumar
- Department of Physics, Rajalakshmi Engineering College, Thandalam, Chennai, Tamil Nadu, India
| | - N. Kanagathara
- Department of Physics, Saveetha School of Engineering, Saveetha Institute of Medical and Technical Sciences, Thandalam, Chennai, Tamil Nadu, India
| | - V. Ragavendran
- Department of Physics, Sri Chandrasekharendra Saraswathi Viswa Mahavidyalaya, Enathur, Kanchipuram, Tamil Nadu, India
| | - V. Natarajan
- Department of Physics, Rajalakshmi Institute of Technology, Kuthambakkam, Chennai, Tamil Nadu, India
| | - M.K. Marchewka
- Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wrocław, Poland
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Taib A, Hammill C, Abraham A, Fakim B, Garstang P, Carney J, Natarajan V, Subar D. Provision of a local anaesthetic minor procedures service by surgical advanced clinical practitioners: 5-year study. BJS Open 2021; 5:6363073. [PMID: 34476465 PMCID: PMC8413366 DOI: 10.1093/bjsopen/zrab073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Accepted: 07/09/2021] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Surgical advanced clinical practitioners (SACPs) form part of the extended surgical workforce drawn from a variety of allied healthcare backgrounds. The primary aim of this study was to determine whether there was a financial benefit in having minor surgical procedures undertaken by dedicated SACPs compared with operating lists assigned to consultant surgeons. METHODS This was a retrospective cohort study including all patients who had minor 'lumps and bumps' procedures undertaken between April 2014 and August 2019 at East Lancashire Hospitals NHS Trust under local anaesthetic by the general surgery team. Clinical patient information, including lesion type, was collected along with operating room staffing levels and duration of operation. The cost of the procedure was calculated as operating time multiplied by cost of staff per minute according to local banding. RESULTS A total of 1399 patients had a lesion excised; 907 procedures were carried out by a doctor, and the rest independently by a SACP. The majority of lesions excised were lipomas and cysts. There was no difference in the median surgical time taken between SACPs and doctors (20 (i.q.r. 14-28) min). Minor procedures carried out on consultant surgeon lists cost 62.3 per cent (€25.33) more on average than those on SACP lists (median €65.96 versus 40.63 respectively; P < 0.001). CONCLUSION A dedicated and independent SACP 'lumps and bumps' list was financially beneficial. Operating times were similar to those of doctors. These lists safely free trainee and consultant surgeons to undertake more complex work.
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Affiliation(s)
- A Taib
- Department of General Surgery, East Lancashire Hospitals NHS Trusts, Blackburn, UK.,Blackburn Research Innovation Development Group in General Surgery (BRIDGES), Blackburn, UK
| | - C Hammill
- Department of General Surgery, East Lancashire Hospitals NHS Trusts, Blackburn, UK.,Blackburn Research Innovation Development Group in General Surgery (BRIDGES), Blackburn, UK
| | - A Abraham
- Department of General Surgery, East Lancashire Hospitals NHS Trusts, Blackburn, UK.,Blackburn Research Innovation Development Group in General Surgery (BRIDGES), Blackburn, UK
| | - B Fakim
- Department of General Surgery, East Lancashire Hospitals NHS Trusts, Blackburn, UK
| | - P Garstang
- Women's and Children's Division, Lancashire Teaching Hospitals NHS Foundation Trust, Preston, UK
| | - J Carney
- Department of General Surgery, East Lancashire Hospitals NHS Trusts, Blackburn, UK
| | - V Natarajan
- Department of General Surgery, East Lancashire Hospitals NHS Trusts, Blackburn, UK
| | - D Subar
- Department of General Surgery, East Lancashire Hospitals NHS Trusts, Blackburn, UK.,Blackburn Research Innovation Development Group in General Surgery (BRIDGES), Blackburn, UK
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Kanagathara N, Usha R, Natarajan V, Marchewka M. Molecular geometry, vibrational, NBO, HOMO–LUMO, first order hyper polarizability and electrostatic potential studies on anilinium hydrogen oxalate hemihydrate – an organic crystalline salt. INORG NANO-MET CHEM 2021. [DOI: 10.1080/24701556.2021.1891103] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- N. Kanagathara
- Department of Physics, Saveetha School of Engineering, SIMATS, Chennai, Tamil Nadu, India
| | - R. Usha
- Department of Physics, Saveetha School of Engineering, SIMATS, Chennai, Tamil Nadu, India
| | - V. Natarajan
- Department of Physics, Rajalakshmi Institute of Technology, Chennai, Tamil Nadu, India
| | - M.K. Marchewka
- Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Poland
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Senthilkumar K, Kanagathara N, Natarajan V, Ragavendran V, Srinivasan T, Marchewka M. Single crystal X-ray diffraction, spectral characterization, evaluation of electronic and chemical reactivity of tert-butylammonium N-acetylglycinate monohydrate – A DFT study. J Mol Struct 2020. [DOI: 10.1016/j.molstruc.2020.128764] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Natarajan V, Ramanathan P, Gopisetty G, Ramachandran B, Thangarajan R, Kesavan S. In silico and in vitro screening of small molecule Inhibitors against SYT-SSX1 fusion protein in synovial sarcoma. Comput Biol Chem 2018; 77:36-43. [PMID: 30219714 DOI: 10.1016/j.compbiolchem.2018.09.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 09/04/2018] [Accepted: 09/04/2018] [Indexed: 12/30/2022]
Abstract
Synovial sarcoma (SS) is characterized by a tumour specific chromosomal translocation t(X;18) (p11;q11) which results in the formation of SYT-SSX1 fusion protein. This fusion protein represents a clear therapeutic target and molecules specifically targeting SYT-SSX1 fusion protein are currently not available. In this study, SYT-SSX1 fusion protein sequence was retrieved from Uniprot and 3D structure was generated using I-TASSER modeling program. A structure based computational screening approach has been employed using Glide docking software to identify potential SYT-SSX1 small molecule inhibitors that bind to the junction region of the fusion protein. The obtained inhibitors were further filtered based on the docking score and ADME/T properties. Ten best fit compounds were chosen for in vitro studies. The anti-proliferative activities of these 10 compounds were screened in Yamato, ASKA (carries SYT-SSX1 fusion protein) and other sarcoma cell lines such as A673, 143B to understand the specificity of inhibition of the chosen compounds. The in vitro activity was compared against HEK293 cell lines. The compound 5-fluoro-3-(1-phenyl-1H-tetraazol-5-yl)-1H-indole (FPTI) was found to be selectively cytotoxic in synovial sarcoma cell lines (Yamato and ASKA) and this compound also showed insignificant anti proliferative activity on other cell lines. Further, target gene expression study confirmed that FPTI treatment down-regulated SYT-SSX1 and modulated its downstream target genes. Cell cycle analysis revealed the involvement of an apoptotic mechanism of cell death. Further experimental validations may elucidate the therapeutic potentials of FPTI against SYT-SSX1 fusion protein.
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Affiliation(s)
- Valliyammai Natarajan
- Dept of Molecular Oncology, Dr. S. Krishnamurthi Campus, Cancer Institute (WIA), Guindy, Chennai, 600036, India
| | - Priya Ramanathan
- Dept of Molecular Oncology, Dr. S. Krishnamurthi Campus, Cancer Institute (WIA), Guindy, Chennai, 600036, India
| | - Gopal Gopisetty
- Dept of Molecular Oncology, Dr. S. Krishnamurthi Campus, Cancer Institute (WIA), Guindy, Chennai, 600036, India
| | - Balaji Ramachandran
- Dept of Molecular Oncology, Dr. S. Krishnamurthi Campus, Cancer Institute (WIA), Guindy, Chennai, 600036, India
| | - Rajkumar Thangarajan
- Dept of Molecular Oncology, Dr. S. Krishnamurthi Campus, Cancer Institute (WIA), Guindy, Chennai, 600036, India
| | - Sabitha Kesavan
- Dept of Molecular Oncology, Dr. S. Krishnamurthi Campus, Cancer Institute (WIA), Guindy, Chennai, 600036, India.
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Grover S, Natarajan V, Rani S, Reddy S, Bhalla A, Avasthi A. Psychiatric morbidity among elderly presenting to emergency medical department: A study from tertiary hospital in North India. J Geriatr Ment Health 2018. [DOI: 10.4103/jgmh.jgmh_28_17] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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Natarajan V, Harris E, Casey C, Kidambi S. S16-2ROLE OF MATRIX RIGIDITY ON HEPATOCYTES AND LIVER SINUSOIDAL ENDOTHELIAL CELLS IN ALCOHOL INDUCED HEPATIC FIBROGENESIS. Alcohol Alcohol 2017. [DOI: 10.1093/alcalc/agx075.60] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Bormann C, Kanakasabapathy M, Thirumalaraju P, Yogesh V, Natarajan V, Demick J, Blanchard A, Petrozza J, Shafiee H. Smartphone-based optical system for sperm viability testing. Fertil Steril 2017. [DOI: 10.1016/j.fertnstert.2017.07.234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Kanakasabapathy M, Thirumalaraju P, Yogesh V, Natarajan V, Bormann C, Bhowmick P, Veiga C, Petrozza J, Shafiee H. Automated smartphone-based system for semen assessment through the hyaluronic binding assay. Fertil Steril 2017. [DOI: 10.1016/j.fertnstert.2017.07.233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Raghavendra Prasad B, Banerjee D, Singh J, Nagabhushana S, Kumar A, Kamath PU, Kathiravan S, Venkata S, Rajkumar N, Natarajan V, Juneja M, Somu P, Pant V, Shaji N, Sankarsubramanian K, Patra A, Venkateswaran R, Adoni AA, Narendra S, Haridas TR, Mathew SK, Mohan Krishna R, Amareswari K, Jaiswal B. Visible Emission Line Coronagraph on Aditya-L1. CURR SCI INDIA 2017. [DOI: 10.18520/cs/v113/i04/613-615] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Abstract
Bioethanol is a potential alternative fuel to fossil fuels. Bioethanol as a fuel has several economic and environmental benefits. Though bioethanol is produced using starch and sugarcane juice, these materials are in conflict with food availability. To avoid food-fuel conflict, the second-generation bioethanol production by utilizing nonfood lignocellulosic materials has been extensively investigated. However, due to the complexity of lignocellulose architecture, the process is complicated and not economically competitive. The cultivation of lignocellulosic energy crops indirectly affects the food supplies by extensive land use. Marine algae have attracted attention to replace the lignocellulosic feedstock for bioethanol production, since the algae grow fast, do not use land, avoid food-fuel conflict and have several varieties to suit the cultivation environment. The composition of algae is not as complex as lignocellulose due to the absence of lignin, which renders easy hydrolysis of polysaccharides to fermentable sugars. Marine organisms also produce cold-active enzymes for hydrolysis of starch, cellulose, and algal polysaccharides, which can be employed in bioethanol process. Marine microoorganisms are also capable of fermenting sugars under high salt environment. Therefore, marine biocatalysts are promising for development of efficient processes for bioethanol production.
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Affiliation(s)
- M R Swain
- Indian Institute of Technology Madras, Chennai, India
| | - V Natarajan
- Indian Institute of Technology Madras, Chennai, India
| | - C Krishnan
- Indian Institute of Technology Madras, Chennai, India.
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Nan L, Wei J, Zhao J, Jacko AM, Zhao Y, Natarajan V, Ma H. ID: 115: TRKA TRANSACTIVATION BY LYSOPHOSPHATIDIC ACID REGULATES LUNG EPITHELIAL CELL MIGRATION. J Investig Med 2016. [DOI: 10.1136/jim-2016-000120.113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BackgroundLysophosphatidic acid (LPA) is a bioactive lysophospholipid, which plays a crucial role in cell proliferation, migration, and differentiation. LPA exerts its biological effects mainly through cell-surface LPA receptors (LPA1-6), which belong to the G protein-coupled receptor (GPCR) family. Recent studies suggest that cross-talk between receptor tyrosine kinases (RTKs) and GPCRs modulates GPCR-mediated signaling. TrkA receptor is a RTK, which mediates nerve growth factor (NGF)-induced biological functions including cell migration in neuronal and non-neuronal tissues.Methods and ResultsHere, we show that LPA treatment of the murine lung epithelial cell line (MLE-12 cells) induced tyrosine phosphorylation of TrkA in both time- and dose-dependent manners. These effects were attenuated by downregulating the LPA1 receptor. Furthermore, LPA induces interaction between LPA1 and TrkA. Co-immunoprecipitation experiment reveals that c-terminus of LPA1 contains the binding site for TrkA. Further, we found that LPA1 and phosphorylated TrkA were co-localized in both the plasma membrane and cytoplasm. Pretreatment with a TrkA inhibitor attenuated LPA-induced phosphorylation of TrkA receptor and LPA1 internalization as well as lung epithelial cell migration.ConclusionThese studies reveal a molecular mechanism for the transactivation of TrkA by LPA, and suggest that the cross-talk between LPA1 and TrkA regulates LPA-induced receptor internalization and lung epithelial cell migration.This work was supported by the National Institutes of Health (R01HL091916 and R01HL112791 to Y.Z, R01GM115389 to J.Z.), American Heart Association 12SDG9050005 (J.Z.), American Lung Association Biomedical Research Grant RG350146 (J.Z.).
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Sysol JR, Chen J, Singla S, Natarajan V, Machado RF, Comhar S, Erzurum SC. ID: 123: ROLE OF MICRORNA-1 IN REGULATING PULMONARY VASCULAR REMODELING IN PULMONARY ARTERIAL HYPERTENSION. J Investig Med 2016. [DOI: 10.1136/jim-2016-000120.120] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
RationalePulmonary arterial hypertension (PAH) is a severe, progressive disease characterized by increased pulmonary arterial pressure and resistance due in part to uncontrolled vascular remodeling. The mechanisms contributing to vascular remodeling in PAH are poorly understood and involve rampant pulmonary artery smooth muscle cell (PASMC) proliferation. We recently demonstrated the important role of sphingosine kinase 1 (SphK1), a lipid kinase producing pro-proliferative sphingosine-1-phosphate (S1P), in the development of pulmonary vascular remodeling in PAH. However, the regulatory processes involved in upregulation of SphK1 in this disease are unknown.ObjectiveIn this study, we aimed to identify novel molecular mechanisms governing the regulation of SphK1 expression, with a focus on microRNA (miR). Using both in vitro studies in pulmonary artery smooth muscle cells (PASMCs) and an in vivo mouse model of experimental hypoxia-mediated pulmonary hypertension (HPH), we explored the role of miR in controlling SphK1 expression in the development of pulmonary vascular remodeling.Methods and ResultsIn silico analysis identified hsa-miR-1-3p (miR-1) as a candidate targeting SphK1. We demonstrate miR-1 is down-regulated by hypoxia in human PASMCs and in lung tissues of mice with HPH, coinciding with upregulation of SphK1 expression. PASMCs isolated from patients with PAH had significantly reduced expression of miR-1. Transfection of human PASMCs with miR-1 mimics significantly attenuated activity of a SphK1-3'-UTR luciferase reporter construct and SphK1 protein expression. miR-1 overexpression in human PASMCs also inhibited proliferation and migration under normoxic and hypoxic conditions, both important in pathogenic vascular remodeling in PAH. Finally, we demonstrated that intravenous administration of miR-1 mimics prevents the development of experimental HPH in mice and attenuates induction of SphK1 in PASMCs.ConclusionThese data demonstrate that miR-1 expression in reduced in PASMCs from PAH patients, is modulated by hypoxia, and regulates the expression of SphK1. Key phenotypic aspects of vascular remodeling are influenced by miR-1 and its overexpression can prevent the development of HPH in mice. These studies further our understanding of the mechanisms underlying pathogenic pulmonary vascular remodeling in PAH and could lead to novel therapeutic targets.Supported by grants NIH/NHLBI R01 HL127342 and R01 HL111656 to RFM, NIH/NHLBI P01 HL98050 and R01 HL127342 to VN, American Heart Association Predoctoral Fellowship (15PRE2190004) to JRS, and NIH/NLHBI NRSA F30 Fellowship (FHL128034A) to JRS.
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Suryadevara V, Royston T, Berdyshev E, Huang L, Natarajan V, Tager A. ID: 112: ROLE OF PHOSPHOLIPASE D IN IDIOPATHIC PULMONARY FIBROSIS. J Investig Med 2016. [DOI: 10.1136/jim-2016-000120.108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Idiopathic pulmonary fibrosis (IPF) is a deadly interstitial disease that leads to scarring and fibrosis of the lung tissue. In pulmonary fibrosis, there is injury and denudation of the alveolar epithelium, which further leads to activation of fibroblasts which differentiate into myofibroblasts. This includes several mechanisms including epithelial to mesenchymal transition (EMT). In this study, we investigated the role of phospholipase D (PLD) in IPF and also its underlying mechanism like EMT and fibroblast proliferation and differentiation. An in vivo murine model of bleomycin-induced pulmonary fibrosis (PF) and in vitro models of murine alveolar type-II epithelial cells (MLE-12) and human lung fibroblasts were used. C57BL/6 and genetically engineered PLD2−/− mice were intratracheally challenged with bleomycin (1.5 U/kg animal) for 14 days and markers of inflammation, EMT and fibrosis were determined. MLE-12 cells were treated with specific PLD1 or PLD2 inhibitors prior to bleomycin (10 mU/ml) challenge, and the role of PLD in EMT and apoptosis of alveolar epithelial cells was studied. Human lung fibroblasts were serum-starved (3h), pretreated with PLD1 or PLD2 inhibitors, and the effect of TGF-β (5 ng/ml) on differentiation of lung fibroblast to myofibroblast was determined. Intra-tracheal instillation of bleomycin in the mice for 14 days leads to the progression of fibrosis in the lung. The lung tissues of the bleomycin treated mice were found to have increased PLD2 protein expression, myofibroblast markers like α-SMA, fibronectin, mesenchymal markers like vimentin, inflammatory cytokines and collagen. Genetic deletion of PLD2 in mice attenuated bleomycin-induced lung inflammation and pulmonary fibrosis. In vitro, MLE-12 cells pretreated with either PLD1 or PLD2 inhibitor did not show a profound reduction either in apoptosis or the expression of transcription factors such as SNAIL, and other markers of EMT. However, MLE-12 cells pretreated with both PLD1 (250 nM) and PLD2 (500 nM) inhibitors were resistant to bleomycin-induced apoptosis, and exhibited reduced expression of SNAIL and mesenchymal markers. On the contrary, human lung fibroblasts pretreated with PLD1 and PLD2 inhibitors showed increased fibroblast to myofibroblast differentiation mediated by TGF-β. The present study suggests a role for PLD2 in bleomycin-induced PF. In vitro, inhibition of both PLD1 and PLD2 was necessary to attenuate bleomycin-induced EMT in epithelial cells and TGF-β mediated differentiation of fibroblasts to myofibroblasts. The in vivo and in vitro results identify the mechanism by which PLD regualtes PF and suggest PLD as a potential therapeutic target in pulmonary fibrosis. This work was supported by National Institutes of Health grant P01 HL98050 to VN.
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Huang L, Natarajan V. ID: 116: ADNIBISTRATION OF SPHINGOSINE KINASE 1 INHIBITOR POST-BLEOMYCIN CHALLENGE ATTENUATES BLEOMYCIN-INDUCED PULMONARY FIBROSIS IN MICE: ROLE OF YAP1. J Investig Med 2016. [DOI: 10.1136/jim-2016-000120.114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
RationaleWe have earlier reported that sphingosine kinase 1 (SphK1) is up-regulated in lung tissues from idiopathic pulmonary fibrosis (IPF) patients and SphK1/sphingosine-1-phosphate (S1P) signaling axis plays a key role in bleomycin- and radiation-induced pulmonary fibrosis in mice. Further, SphK1 mRNA levels in PBMCs from IPF patients directly and significantly correlated with pulmonary function outcomes and overall survival. In this study, we investigated the effect of administration of PF-543, a specific SphK1 inhibitor, 7 days post-bleomycin (BLM) challenge on the development of pulmonary fibrosis in mice.ObjectivesTo determine the efficacy of PF-543 in attenuating pulmonary fibrosis in mice post BLM challenge.MethodsSphK1 inhibitor PF-543 (5 mg/kg body weight, i.p.; twice a week) was administered to control and BLM (1.5 U/kg, intratracheal) challenged mice on day 7 post BLM challenge, and development of pulmonary fibrosis was determined on day 21 by Mason-Trichrome staining of lung tissues, total collagen, fibronectin and α-SMA protein levels in lung tissues. In vitro, the effect of PF-543 on TGF-β (5 ng/ml) induced Yap1 activation, and differentiation, contraction, and proliferation of human lung fibroblast were assessed.ResultsAdministration of PF-543 to BLM treated mice on day 7 post challenge, dramatically inhibited BLM-induced lung injury, and attenuated collagen deposition and expression of fibronectin, α-SMA and TGF-β in lung tissues on day 21 post-BLM challenge. In vitro, PF-543 inhibited TGF-β induced differentiation, contraction and proliferation of human lung fibroblasts, as well as blocked TGF-β induced expression and nuclear translocation of YAP, a transcriptional co-factor involved in pulmonary fibrosis. Additionally, siRNA knockdown of YAP1 inhibited TGF-β induced fibroblast differentiation.ConclusionThese studies demonstrate ability of SphK1 inhibitor, PF-543 to ameliorate BLM-induced pulmonary fibrosis in mice when administered on day 7 after BLM challenge. Also, PF-543 blocked YAP1 activation, a co-transcriptional factor involved in pulmonary fibrosis development. Thus, PF-543 may serve as a potential therapeutic drug in treating pulmonary fibrosis. This work was supported by P01 HL098050 (VN).
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Fu P, Usatyuk PV, Ebenezer DL, Natarajan V. ID: 111: THE S1P TRANSPORTER, SPNS2, MEDIATES HGF-INDUCED LAMELLIPODIA FORMATION AND MIGRATION OF HUMAN LUNG ENDOTHELIAL CELLS. J Investig Med 2016. [DOI: 10.1136/jim-2016-000120.109] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
RationaleWe have demonstrated earlier that HGF-induced lamellipodia formation in human lung microvascular endothelial cells (HLMVECs) was through c-Met receptor tyrosine kinase and PI3 kinase/Akt signal transduction. Here, we show that HGF-mediated lamellipodia formation is dependent on intracellular S1P generation mediated by sphingosine kinase 1 (SphK1), the S1P transporter, Spns2 and S1P1 in HLMVECs.MethodsHLMVECs were treated with HGF (20 ng/ml) for different time points. Lamellipodia were detected after HGF treatment by immunofluorescent staining of Spns2, cortactin and actin in lamellipodia, and lamellipodia were quantified by measuring cell periphery fluorescence intensity. Pearson's correlation coefficient was used to statistically quantify co-localization of proteins in lamellipodia. Endogenous SphK activity was blocked by SphK1 specific inhibitor PF-543, and expression of SphK1 in cells was down-regulated by siRNA. Cellular S1P levels were quantified by mass spectrometry.ResultsHGF stimulated phosphorylation of SphK1, and its localization to lamellipodia of HLMVECs. Down-regulation of SphK1, but not SphK2, with siRNA or inhibition of SphK1 with PF-543 (1–5 µM) attenuated HGF-induced lamellipodia formation in HLMVECs. The HGF-mediated phosphorylation of SphK1 and its localization in lamellipodia was dependent on PI3K/Akt and ERK1/2 signaling apthways. HGF increased S1P levels in HLMVECs, which was blocked by inhibition of SphK1 with PF-543. Further, HGF induced serine phosphorylation and translocation of Spns2, the S1P transporter, to lamellipodia, which was Akt dependent. The HGF-induced lamellipodia formation in HLMVECs was blocked by down-regulation of Spns2, suggesting extracellular action of S1P in lamellipodia formation. Down-regulation of S1P1, but not S1P2 or S1P3, with siRNA attenuated HGF-induced lamellipodia formation. Further, HGF stimulation enhanced association of Spns2 with S1P1 and blocking SphK1 activty with PF-543 attenuated the association between Spns2 and S1P1. Additionally, HGF-induced migration of HLMVECs was attenuated by down-regulation of Spns2.ConclusionThese results suggest that HGF/c-Met mediated lamellipodia formation and motility is dependent on intracellular generation of S1P via activation and localization of SphK1 to cell periphery and Spns2 mediated transport of S1P to outside for signaling via S1P1 in HLMVECs. This work was supported by NIH/HLBI P01 HL98050 to VN.
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Shaaya M, Fu P, Karginov A, Natarajan V. ID: 120: REGULATION OF ENDOTHELIAL BARRIER PERMEABILITY BY PHOSPHOLIPASE D2. J Investig Med 2016. [DOI: 10.1136/jim-2016-000120.118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Pulmonary edema is a hallmark of several diseases including acute respiratory distress syndrome (ARDS) and is characterized by the disruption of the pulmonary endothelial barrier at its early stage. Maintaining the integrity of the adherens junctions (AJs) by stabilizing VE-Cadherin (VEC) at the cell membrane after injury could potentially be important to minimize endothelial barrier disruption. Since Phospholipase D (PLD) and its catalytic product, phosphatidic acid (PA), has been shown to be critical in membrane trafficking and in recycling of a number of cell surface receptors, we hypothesized that PLD/PA pathway accelerates the rate of VEC recycling to the lamellipodia to reassemble the AJs. We demonstrate, by measuring the trans endothelial resistance of human lung microvascular endothelial cells (HLMVECs), that inhibiting PLD2-dependent PA production increases the endothelium permeability in response to thrombin. Furthermore, immunostaining shows that the uniform redistribution of VEC to the AJs post thrombin insult is compromised when PLD-dependent PA production is inhibited, and resulted in the appearance of eminent intercellular gaps. Also, PLD2 inhibition prevented the HLMVECs from fully spreading after thrombin stimulation while the protrusive activity remained unaffected, suggesting that PLD2 is not required by HLMVECs to send protrusions, but is critical for the adherence of the protrusions. LPS-induced lung injury was more severe in PLD2 knockout mice compared to WT in an in vivo ARDS model. These observations suggest that PLD/PA signaling plays an important role in resealing of endothelial gaps post LPS-induced lung injury and could potentially be therapeutically utilized to enhance post-injury endothelium recovery.
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Van Scoyk MM, Avasarala S, Winn RA, Bikkavilli R, Natarajan V, Kotha SR, Huang L. ID: 130: NOVEL ROLE FOR LYSOCARDIOLIPIN ACYLTRANSFERASE (LYCAT) IN NON-SMALL CELL LUNG CANCER. J Investig Med 2016. [DOI: 10.1136/jim-2016-000120.125] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Lung cancer is the leading cause of deaths in United States and non-small cell lung cancer (NSCLC) accounts for ∼85% of all lung cancers with a 5-year survival rate of approximately ∼16%. Therefore there is an immediate need to develop new strategies for early detection and more effective treatments options. Mitochondrial dysfunction including but not limited to defects in mitochondrial genomics and dynamics has long been implicated to play a role in human health and disease particularly in cancer initiation, progression and treatment options since it plays a pivotal role in cell death and survival. Lysocardiolipin acyltransferase (LYCAT), a Cardiolipin remodeling enzyme regulating the 18:2 linoleic acid pattern of mammalian mitochondrial cardiolipin, plays a crucial role in maintaining normal mitochondrial function and vascular development. LYCAT was shown to be up-regulated in cancers; however, the role of LYCAT in lung cancer is yet unclear. Probing the protein expression of LYCAT in lung cancer specimens, non-transformed bronchial epithelial cell lines and 5 lung cancer cell lines revealed increased LYCAT expression and activity in all the lung cancer samples and cell lines tested in comparison to the control lung tissues and non-transformed epithelial cell lines. To determine the role of LYCAT in lung cancer, NSCLC cell lines H2122 and H23 were transfected with either scrambled or LYCAT shRNA and differences in serum-induced cell proliferation, migration, clonogenecity and mitochondrial dynamics were determined. Our results demonstrated that down-regulation of LYCAT by shRNA significantly attenuated cell migration, proliferation, and invasion in NSCLC cell lines compared to control cell lines. Furthermore knockdown of LYCAT expression in NSCLC cell lines inhibited mitochondrial fragmentation and enhanced mitochondrial fusion. Taken together, these data demonstrate a strong association between increased LYCAT expression and cell proliferation, motility, invasion and mitochondrial dynamics in NSCLC cells. Thus, development of targeted therapies to reduce LYCAT expression in NSCLC should be beneficial. This work in part was supported by funds from the College of Medicine, UIC and NIH HL98050 to VN.
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Sharma S, Singh B, Thulasidas SK, Kulkarni MJ, Natarajan V, Manchanda VK. Evaluation of terrestrial plants extracts for uranium sorption and characterization of potent phytoconstituents. Int J Phytoremediation 2016; 18:10-15. [PMID: 25946322 DOI: 10.1080/15226514.2015.1045126] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Sorption capacity of four plants (Funaria hygrometrica, Musa acuminata, Brassica juncea and Helianthus annuus) extracts/fractions for uranium, a radionuclide was investigated by EDXRF and tracer studies. The maximum sorption capacity, i.e., 100% (complete sorption) was observed in case of Musa acuminata extract and fractions. Carbohydrate, proteins, phenolics and flavonoids contents in the active fraction (having maximum sorption capacity) were also determined. Further purification of the most active fraction provided three pure molecules, mannitol, sorbitol and oxo-linked potassium oxalate. The characterization of isolated molecules was achieved by using FTIR, NMR, GC-MS, MS-MS, and by single crystal-XRD analysis. Of three molecules, oxo-linked potassium oxalate was observed to have 100% sorption activity. Possible binding mechanism of active molecule with the uranyl cation has been purposed.
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Affiliation(s)
- Sunita Sharma
- a Natural Product Chemistry and Process Development Division, CSIR-Institute of Himalayan Bioresource Technology , Palampur , Himachal Pradesh , India
| | - Bikram Singh
- a Natural Product Chemistry and Process Development Division, CSIR-Institute of Himalayan Bioresource Technology , Palampur , Himachal Pradesh , India
| | - S K Thulasidas
- b Radiochemistry Division, Bhabha Atomic Research Centre , Mumbai , India
| | - Madhuri J Kulkarni
- b Radiochemistry Division, Bhabha Atomic Research Centre , Mumbai , India
| | - V Natarajan
- b Radiochemistry Division, Bhabha Atomic Research Centre , Mumbai , India
| | - Vijay K Manchanda
- b Radiochemistry Division, Bhabha Atomic Research Centre , Mumbai , India
- c Department of Energy Science, Sungkyunkwan University , Suwon , Korea
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Gupta SK, Rajeshwari B, Achary SN, Patwe SJ, Tyagi AK, Natarajan V, Kadam RM. Europium Luminescence as a Structural Probe: Structure-Dependent Changes in Eu3+-Substituted Th(C2O4)2·xH2O (x= 6, 2, and 0). Eur J Inorg Chem 2015. [DOI: 10.1002/ejic.201500623] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Natarajan V, Usharani S, Arivanandhan M, Anandan P, Hayakawa Y. Effect of solvents on the bulk growth of 4-aminobenzophenone single crystals: a potential material for blue and green lasers. Spectrochim Acta A Mol Biomol Spectrosc 2015; 145:329-332. [PMID: 25795606 DOI: 10.1016/j.saa.2015.03.051] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Revised: 12/23/2014] [Accepted: 03/02/2015] [Indexed: 06/04/2023]
Abstract
Although 4-aminobenzophenone (4-ABP) is the best derivative of benzophenone with 260 times higher second harmonic generation (SHG) efficiency than potassium dihydrogen phosphate (KDP), growth of high quality bulk crystal still remains a difficult task. In the present work, the effect of solvents on solubility and growth aspects of 4-ABP was investigated to grow inclusion free 4-ABP crystals. The growth processes were discussed based on solute-solvent interaction in two different growth media of ethyl acetate and ethanol. The growth rate and thereby solvent inclusions are relatively higher in ethyl acetate grown crystal than the crystal grown from ethanol. The structural, thermal and optical properties of 4-ABP crystals were studied. The enthalpy of 4-ABP melting process was estimated from differential thermal analysis. The optical transmission study shows that 4-ABP crystals grown from ethanol has high transparency compared to ethyl acetate grown sample due to solvent inclusion in the later crystal.
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Affiliation(s)
- V Natarajan
- Department of Physics, Dr. Sivanthi Aditanar College of Engineering, Tiruchendur 628215, India.
| | - S Usharani
- Department of Physics, Dr. Sivanthi Aditanar College of Engineering, Tiruchendur 628215, India
| | - M Arivanandhan
- Research Institute of Electronics, Shizuoka University, Johoku 3-5-1, Naka-Ku, Hamamatsu 432-8011, Japan
| | - P Anandan
- Department of Physics, Thiruvalluvar College of Engineering and Technology, Vandavasi 604505, India
| | - Y Hayakawa
- Research Institute of Electronics, Shizuoka University, Johoku 3-5-1, Naka-Ku, Hamamatsu 432-8011, Japan
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Sivakamasundari J, Kavitha G, Natarajan V, Ramakrishnan S. An Approach to Content Based Retinal Image Retrieval Using Papamarkos Multilevel Thresholding Method. J Med Imaging Hlth Inform 2015. [DOI: 10.1166/jmihi.2015.1419] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Raj SS, Gupta SK, Grover V, Muthe K, Natarajan V, Tyagi A. MgAl2O4 spinel: Synthesis, carbon incorporation and defect-induced luminescence. J Mol Struct 2015. [DOI: 10.1016/j.molstruc.2015.02.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Gupta SK, Dhobale A, Kumar M, Godbole S, Natarajan V. Oxidation state determination of uranium in various uranium oxides: Photoacoustic spectroscopy complimented by photoluminescence studies. J Mol Struct 2015. [DOI: 10.1016/j.molstruc.2014.12.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Kadam RM, Rajeswari B, Sengupta A, Achary SN, Kshirsagar RJ, Natarajan V. Structural characterization of titania by X-ray diffraction, photoacoustic, Raman spectroscopy and electron paramagnetic resonance spectroscopy. Spectrochim Acta A Mol Biomol Spectrosc 2015; 137:363-370. [PMID: 25233027 DOI: 10.1016/j.saa.2014.08.082] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Revised: 08/12/2014] [Accepted: 08/23/2014] [Indexed: 06/03/2023]
Abstract
A titania mineral (obtained from East coast, Orissa, India) was investigated by X-ray diffraction (XRD), photoacoustic spectroscopy (PAS), Raman and Electron Paramagnetic Resonance (EPR) studies. XRD studies indicated the presence of rutile (91%) and anatase (9%) phases in the mineral. Raman investigation supported this information. Both rutile and anatase phases have tetragonal structure (rutile: space group P4(2)/mnm, a=4.5946(1) Å, c=2.9597(1) Å, V=62.48(1) (Å)(3), Z=2; anatase: space group I4(1)/amd, 3.7848(2) Å, 9.5098(11) Å, V=136.22(2) (Å)(3), Z=4). The deconvoluted PAS spectrum showed nine peaks around 335, 370, 415,485, 555, 605, 659, 690,730 and 785 nm and according to the ligand field theory, these peaks were attributed to the presence of V(4+), Cr(3+), Mn(4+) and Fe(3+) species. EPR studies revealed the presence of transition metal ions V(4+)(d(1)), Cr(3+)(d(3)), Mn(4+)(d(3)) and Fe(3+)(d(5)) at Ti(4+) sites. The EPR spectra are characterized by very large crystal filed splitting (D term) and orthorhombic distortion term (E term) for multiple electron system (s>1) suggesting that the transition metal ions substitute the Ti(4+) in the lattice which is situated in distorted octahedral coordination of oxygen. The possible reasons for observation of unusually large D and E term in the EPR spectra of transition metal ions (S=3/2 and 5/2) are discussed.
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Affiliation(s)
- R M Kadam
- Radiochemistry Division, Bhabha Atomic Research Centre, Trombay 400 085, India.
| | - B Rajeswari
- Radiochemistry Division, Bhabha Atomic Research Centre, Trombay 400 085, India
| | - Arijit Sengupta
- Radiochemistry Division, Bhabha Atomic Research Centre, Trombay 400 085, India
| | - S N Achary
- Chemistry Division, Bhabha Atomic Research Centre, Trombay 400 085, India
| | - R J Kshirsagar
- High Pressure & Synchrotron Radiation Physics Division, Bhabha Atomic Research Centre, Trombay 400 085, India
| | - V Natarajan
- Radiochemistry Division, Bhabha Atomic Research Centre, Trombay 400 085, India
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Suman SK, Dubey KA, Mishra BB, Bhardwaj YK, Mondal RK, Seshadri M, Natarajan V, Varshney L. Synthesis of a flexible poly(chloroprene)/methyl red film dosimeter using an environment-benign shear compounding method. Appl Radiat Isot 2015; 98:60-5. [PMID: 25638574 DOI: 10.1016/j.apradiso.2015.01.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Revised: 01/20/2015] [Accepted: 01/20/2015] [Indexed: 11/25/2022]
Abstract
The paper reports synthesis of a new film dosimeter based on a solvent-free route. Methyl red (MR) dye was introduced into poly(chloroprene) (PC) in various concentrations. The films were intensely red with λmax ~515nm. The absorbance decreased linearly with absorbed radiation dose up to 30kGy without a significant change in λmax. Color coordinates of the films were also analyzed. Optical micrographs of the films showed no signs of inhomogeneous distribution of MR in the PC matrix, which was attributed to the polarity of PC. Radiation sensitivity, dose response linearity, effects of irradiation temperature and humidity, as well as the rate of fading, were also investigated.
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Affiliation(s)
- S K Suman
- Radiation Safety Systems Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
| | - K A Dubey
- Radiation Technology Development Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India.
| | - B B Mishra
- Food Technology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
| | - Y K Bhardwaj
- Radiation Technology Development Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
| | - R K Mondal
- Radiation Technology Development Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
| | - Murali Seshadri
- Radiation Safety Systems Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
| | - V Natarajan
- Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
| | - L Varshney
- Radiation Technology Development Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
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Pathak N, Gupta SK, Ghosh PS, Arya A, Natarajan V, Kadam RM. Probing local site environments and distribution of manganese in SrZrO3:Mn; PL and EPR spectroscopy complimented by DFT calculations. RSC Adv 2015. [DOI: 10.1039/c4ra15141k] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In order to understand the local environment, valence state and distribution of manganese; a combined experimental and theoretical approach based on PL, EPR and DFT is reported for Sr(1−x)Zr(1−y)Mn(x+y)O3, also explaining the origin of various defect related emissions.
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Affiliation(s)
- Nimai Pathak
- Radio Chemistry Division
- Bhabha Atomic Research Centre
- Mumbai-400085
- India
| | - Santosh K. Gupta
- Radio Chemistry Division
- Bhabha Atomic Research Centre
- Mumbai-400085
- India
| | - P. S. Ghosh
- Materials Science Division
- Bhabha Atomic Research Centre
- Mumbai-400085
- India
| | - A. Arya
- Materials Science Division
- Bhabha Atomic Research Centre
- Mumbai-400085
- India
| | - V. Natarajan
- Radio Chemistry Division
- Bhabha Atomic Research Centre
- Mumbai-400085
- India
| | - R. M. Kadam
- Radio Chemistry Division
- Bhabha Atomic Research Centre
- Mumbai-400085
- India
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Gupta SK, Ghosh PS, Sahu M, Bhattacharyya K, Tewari R, Natarajan V. Intense red emitting monoclinic LaPO4:Eu3+ nanoparticles: host–dopant energy transfer dynamics and photoluminescence properties. RSC Adv 2015. [DOI: 10.1039/c5ra09076h] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Visible host emission and dynamics of host–dopant energy transfer in LaPO4:Eu phosphor is investigated using PL and complimented by DFT.
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Affiliation(s)
- Santosh K. Gupta
- Radiochemistry Division
- Bhabha Atomic Research Centre
- Mumbai 400085
- India
| | - P. S. Ghosh
- Materials Science Division
- Bhabha Atomic Research Centre
- Mumbai 400085
- India
| | - M. Sahu
- Radioanalytical Chemistry Division
- Bhabha Atomic Research Centre
- Mumbai 400085
- India
| | - K. Bhattacharyya
- Chemistry Division
- Bhabha Atomic Research Centre
- Mumbai 400085
- India
| | - R. Tewari
- Materials Science Division
- Bhabha Atomic Research Centre
- Mumbai 400085
- India
| | - V. Natarajan
- Radiochemistry Division
- Bhabha Atomic Research Centre
- Mumbai 400085
- India
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Shukla R, Gupta SK, Grover V, Natarajan V, Tyagi AK. The role of reaction conditions in the polymorphic control of Eu3+ doped YInO3: structure and size sensitive luminescence. Dalton Trans 2015; 44:10628-35. [DOI: 10.1039/c4dt02717e] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Controlled synthetic conditions yielded YInO3:Eu3+ in both C-type and hexagonal modifications which exhibited a tremendous bearing of size and local structure on Eu3+ luminescence, all in a single compound.
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Affiliation(s)
- R. Shukla
- Chemistry Division
- Bhabha Atomic Research Centre
- Mumbai-400085
- India
| | - Santosh K. Gupta
- Radiochemistry Division
- Bhabha Atomic Research Centre
- Mumbai-400085
- India
| | - V. Grover
- Chemistry Division
- Bhabha Atomic Research Centre
- Mumbai-400085
- India
| | - V. Natarajan
- Radiochemistry Division
- Bhabha Atomic Research Centre
- Mumbai-400085
- India
| | - A. K. Tyagi
- Chemistry Division
- Bhabha Atomic Research Centre
- Mumbai-400085
- India
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Kumar CV, Natarajan V, Poonguzhali P. Secured patient information transmission using reversible watermarking and DNA encrytion for medical images. ACTA ACUST UNITED AC 2015. [DOI: 10.12988/ams.2015.53219] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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36
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Sivakamasundari J, Natarajan V. Design of Content Based Image Retrieval Scheme for Diabetic Retinopathy Images using Harmony Search Algorithm. Biomed Sci Instrum 2015; 51:273-280. [PMID: 25996728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Diabetic Retinopathy (DR) is a disorder that affects the structure of retinal blood vessels due to long-standing diabetes mellitus. Automated segmentation of blood vessel is vital for periodic screening and timely diagnosis. An attempt has been made to generate continuous retinal vasculature for the design of Content Based Image Retrieval (CBIR) application. The typical normal and abnormal retinal images are preprocessed to improve the vessel contrast. The blood vessels are segmented using evolutionary based Harmony Search Algorithm (HSA) combined with Otsu Multilevel Thresholding (MLT) method by best objective functions. The segmentation results are validated with corresponding ground truth images using binary similarity measures. The statistical, textural and structural features are obtained from the segmented images of normal and DR affected retina and are analyzed. CBIR in medical image retrieval applications are used to assist physicians in clinical decision-support techniques and research fields. A CBIR system is developed using HSA based Otsu MLT segmentation technique and the features obtained from the segmented images. Similarity matching is carried out between the features of query and database images using Euclidean Distance measure. Similar images are ranked and retrieved. The retrieval performance of CBIR system is evaluated in terms of precision and recall. The CBIR systems developed using HSA based Otsu MLT and conventional Otsu MLT methods are compared. The retrieval performance such as precision and recall are found to be 96% and 58% for CBIR system using HSA based Otsu MLT segmentation. This automated CBIR system could be recommended for use in computer assisted diagnosis for diabetic retinopathy screening.
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Gupta R, Gupta SK, Gamre JS, Lohithakshan KV, Natarajan V, Aggarwal SK. Understanding the Dynamics of Eu
3+
Ions in Room‐Temperature Ionic Liquids – Electrochemical and Time‐Resolved Fluorescence Spectroscopy Studies. Eur J Inorg Chem 2014. [DOI: 10.1002/ejic.201402713] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Ruma Gupta
- Fuel Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, India
| | - Santosh K. Gupta
- Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, India
| | - J. S. Gamre
- Fuel Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, India
| | - K. V. Lohithakshan
- Fuel Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, India
| | - V. Natarajan
- Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, India
| | - S. K. Aggarwal
- Fuel Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, India
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Sengupta A, Thulasidas SK, Natarajan V. Trace level determination of precious metals in aqueous medium, U, Th and Zr based nuclear materials by ICP-AES and EDXRF: a comparative study. J Radioanal Nucl Chem 2014. [DOI: 10.1007/s10967-014-3679-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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39
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40
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Gupta SK, Pathak N, Sahu M, Natarajan V. A Novel near white light emitting nanocrystalline Zn2P2O7:Sm3+ derived using citrate precursor route: Photoluminescence spectroscopy. ADV POWDER TECHNOL 2014. [DOI: 10.1016/j.apt.2014.03.023] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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41
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Gupta SK, Pathak N, Gupta R, Thulasidas S, Natarajan V. Probing the oxidation state and coordination geometry of uranium ion in SrZrO3 perovskite. J Mol Struct 2014. [DOI: 10.1016/j.molstruc.2014.04.016] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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42
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Gupta SK, Dhobale AR, Natarajan V, Godbole SV. Optical properties of ammonium uranyl fluoride characterized by photoluminescence and photoacoustic spectroscopy. Spectrochim Acta A Mol Biomol Spectrosc 2014; 117:204-209. [PMID: 23994675 DOI: 10.1016/j.saa.2013.07.104] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Revised: 07/23/2013] [Accepted: 07/31/2013] [Indexed: 06/02/2023]
Abstract
PL and PAS studies were performed on uranyl compounds viz. uranium oxalate, uranium fluoride and ammonium uranyl fluoride. PL and PAS spectrum of ammonium uranyl fluoride is being reported for the first time. Ammonium uranyl fluoride is blue shifted with respect to uranyl fluoride, as a result of ammonium bonding. The vibronic separations were determined in the excited state and the ground state using excitation/PA spectra and emission spectra respectively. Fluorescence decay data could be fitted only with biexponential decay in all of these compounds indicating the presence of two different environments in these compounds. Low temperature luminescence leads to enhancement in emission intensity and lifetime value. The temperature dependence studies of average fluorescence lifetimes of ammonium uranyl are described in this paper. Based on this studies activation energy value for ammonium uranyl fluoride at which (3)∏ and (1)Σ potential surfaces will cross is calculated.
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Affiliation(s)
- Santosh K Gupta
- Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, India.
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43
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Gupta SK, Ghosh PS, Pathak N, Arya A, Natarajan V. Understanding the local environment of Sm3+ in doped SrZrO3 and energy transfer mechanism using time-resolved luminescence: a combined theoretical and experimental approach. RSC Adv 2014. [DOI: 10.1039/c4ra04262j] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A combined experimental and theoretical study on the photoluminescence (PL) properties of strontium zirconate (SZ) and Sm3+ doped SZ nanostructures is presented in this work.
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Affiliation(s)
- Santosh K. Gupta
- Radiochemistry Division
- Bhabha Atomic Research Centre
- Mumbai-400085, India
| | - P. S. Ghosh
- Materials Science Division
- Bhabha Atomic Research Centre
- Mumbai-400085, India
| | - Nimai Pathak
- Radiochemistry Division
- Bhabha Atomic Research Centre
- Mumbai-400085, India
| | - A. Arya
- Materials Science Division
- Bhabha Atomic Research Centre
- Mumbai-400085, India
| | - V. Natarajan
- Radiochemistry Division
- Bhabha Atomic Research Centre
- Mumbai-400085, India
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Gupta SK, Ghosh PS, Arya A, Natarajan V. Origin of blue emission in ThO2 nanorods: exploring it as a host for photoluminescence of Eu3+, Tb3+ and Dy3+. RSC Adv 2014. [DOI: 10.1039/c4ra09681a] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Nanorods of ThO2 were synthesized in a reverse micelle technique using cetyl trimethyl ammonium bromide as a surfactant and characterized by X-ray diffraction and transmission electron microscopy.
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Affiliation(s)
- Santosh K. Gupta
- Radiochemistry Division
- Bhabha Atomic Research Centre
- Mumbai-400085, India
| | - P. S. Ghosh
- Materials Science Division
- Bhabha Atomic Research Centre
- Mumbai-400085, India
| | - A. Arya
- Materials Science Division
- Bhabha Atomic Research Centre
- Mumbai-400085, India
| | - V. Natarajan
- Radiochemistry Division
- Bhabha Atomic Research Centre
- Mumbai-400085, India
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Pathak N, Gupta SK, Sanyal K, Kumar M, Kadam RM, Natarajan V. Photoluminescence and EPR studies on Fe3+ doped ZnAl2O4: an evidence for local site swapping of Fe3+ and formation of inverse and normal phase. Dalton Trans 2014; 43:9313-23. [DOI: 10.1039/c4dt00741g] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Gupta SK, Mohapatra M, Godbole SV, Natarajan V. On the unusual photoluminescence of Eu3+ in α-Zn2P2O7: a time resolved emission spectrometric and Judd–Ofelt study. RSC Adv 2013. [DOI: 10.1039/c3ra43027h] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Srimathy B, Jayavel R, Ganesamoorthy S, Bhaumik I, Karnal AK, Natarajan V, Varadarajan E, Kumar J. Crystal growth of PZN-PT single crystals and critical issues for higher piezoelectric coefficient. Cryst Res Technol 2012. [DOI: 10.1002/crat.201100580] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Doraiswamy H, Natarajan V. Output-Sensitive Construction of Reeb Graphs. IEEE Trans Vis Comput Graph 2012; 18:146-159. [PMID: 21301023 DOI: 10.1109/tvcg.2011.37] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The Reeb graph of a scalar function represents the evolution of the topology of its level sets. This paper describes a near-optimal output-sensitive algorithm for computing the Reeb graph of scalar functions defined over manifolds or non-manifolds in any dimension. Key to the simplicity and efficiency of the algorithm is an alternate definition of the Reeb graph that considers equivalence classes of level sets instead of individual level sets. The algorithm works in two steps. The first step locates all critical points of the function in the domain. Critical points correspond to nodes in the Reeb graph. Arcs connecting the nodes are computed in the second step by a simple search procedure that works on a small subset of the domain that corresponds to a pair of critical points. The paper also describes a scheme for controlled simplification of the Reeb graph and two different graph layout schemes that help in the effective presentation of Reeb graphs for visual analysis of scalar fields. Finally, the Reeb graph is employed in four different applications-surface segmentation, spatially-aware transfer function design, visualization of interval volumes, and interactive exploration of time-varying data.
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Sivakamasundari J, Kavitha G, Natarajan V, Ramakrishnan S. Characterization of optic disc in human retinal images using tsallis entropy based method. Biomed Sci Instrum 2012; 48:524-531. [PMID: 22846328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The detection of the optic disc is an important step in the automated analysis of retinal images. A method to identify the optic disc in human retinal images using, non-extensive entropy, also called Tsallis entropy, is presented in this paper. The segmentation process is carried out on the retinal images using conventional Tsallis entropy, with and without morphological preprocessing. An optimum threshold value is found to separate optic disc from the blood vessels and other structures. The performance of the conventional Tsallis algorithm with and without preprocessing is compared and analyzed based on the different entropic index, visual quality, pixel distribution and the geometrical size of the optic disc. The conventional Tsallis entropy with morphological preprocessing is able to segment the optic disc. The detection efficiency is found to be high for the entropic index equal to 4 and also it is found that optic disc index is a useful parameter to differentiate normal from abnormal retinal images. The results are useful for detection of various retinal related diseases.
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Rajeswari B, Kadam RM, Dhawale BA, Babu Y, Natarajan V, Godbole SV. EPR evidence for the restricted mobility of NO2 in gamma irradiated thorium nitrate pentahydrate Th(NO3)4·5H2O. Spectrochim Acta A Mol Biomol Spectrosc 2011; 79:405-411. [PMID: 21524936 DOI: 10.1016/j.saa.2011.02.031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Revised: 02/01/2011] [Accepted: 02/16/2011] [Indexed: 05/30/2023]
Abstract
Electron paramagnetic resonance (EPR) studies were conducted on gamma irradiated polycrystalline sample of thorium nitrate pentahydrate, Th(NO(3))(4)·5H(2)O, in the temperature range of 100-300 K. The most prominent species with triplet hyperfine structure in the EPR spectrum was identified as NO(2). The EPR spectrum gave evidence for the stabilization of NO(2) in at least three different sites slightly differing in spin Hamiltonian parameters (Site(1): g(x)=2.0042, g(y)=1.9911, g(z)=2.0020, A(x)=54.20 G, A(y)=48.50 G and A(z)=65.25 G; Site(2): g(x)=2.0042, g(y)=1.9911, g(z)=2.0020, A(x)=54.20 G, A(y)=48.50 G and A(z)=67.85 G; Site(3): g(x)=2.0045, g(y)=1.9911, g(z)=2.0015, A(x)=54.20 G, A(y)=49.05 G and A(z)=72.45 G). The EPR spectra for Site(1) revealed molecular dynamics of NO(2) from a slow motion region to fast motion region as the sample temperature was varied from 100 to 300 K. This led to a change in EPR spectrum from orthorhombic to axial, indicating preferred rotation of NO(2) molecule about the O-O bond direction. However, the NO(2) molecule at Site(2) was found to be rigid throughout the entire temperature range. The differences in the mobility of NO(2) molecules occupying the two sites could be attributed to the fact that in one case NO(2) was bonded to thorium or water and in the other case it was weakly bound. The NO(2) bound to thorium through two oxygen atoms or bound to thorium on one side through one oxygen atom and hydrogen bonded to water on the other side remains rigid throughout the entire temperature range, while NO(2) situated at interstitial sites or adsorbed on the surface exhibits mobility with increase in temperature above 100K.
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Affiliation(s)
- B Rajeswari
- Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India
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