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Chandrasekhar S, Raghu MS, Yogesh Kumar K, Alharethy F, Prashanth MK, Jeon BH. Theoretical and experimental investigation of novel quinazoline derivatives: synthesis, photophysical, reactive properties, molecular docking and selective HSA biointeraction. J Biomol Struct Dyn 2023:1-16. [PMID: 37477248 DOI: 10.1080/07391102.2023.2237590] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/22/2023]
Abstract
Two new quinazoline derivatives (2a and 2b) were successfully synthesized in this work using the condensation technique in excellent yields. Using spectroscopic techniques and elemental analyses, the compounds were completely characterized. Density functional theory (DFT) computations have been used to examine the title compound's reactive characteristics. Chemical reactivity was predicted using local reactive descriptors and molecule electrostatic potential. Additionally, Time dependent DFT (TD-DFT) simulations were used to examine the impact of solvents on the photophysical characteristics. The affinity of compounds 2a and 2b for human serum albumin (HSA) was further explored using several electronic spectroscopies. Through static mechanisms, both compounds reduce the intrinsic fluorescence of HSA. It is determined that the HSA-2b complex's binding constant is significantly greater than the HSA-2a complex. The fluorescence spectrum measurements proved that the HSA underwent structural changes after interaction with these compounds. It was demonstrated by site marker competitive displacement studies that compounds 2a and 2b preferred to bind to site I in HSA subdomain IIA. Additionally, synchronised fluorescence spectra were utilized to analyze how HSA's conformation changed after interacting with various substances. The molecular docking investigations of these compounds with the three critical HSA binding sites, comprising subdomains IIA, IIIA, and IB, further confirmed the experimental findings. The significant contact between the investigated compounds and HSA was supported by the docking simulations.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- S Chandrasekhar
- Department of Physics, B N M Institute of Technology, Bengaluru, India
| | - M S Raghu
- Department of Chemistry, New Horizon College of Engineering, Bengaluru, India
| | - K Yogesh Kumar
- Department of Chemistry, Faculty of Engineering and Technology, Jain University, Ramanagara, India
| | - Fahd Alharethy
- Department of Chemistry, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - M K Prashanth
- Department of Chemistry, B N M Institute of Technology, Bengaluru, India
| | - Byong-Hun Jeon
- Department of Earth Resources and Environmental Engineering, Hanyang University, Seoul, Republic of Korea
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Veena K, Chandrasekhar S, Raghu M, Yogesh Kumar K, Pradeep Kumar C, Alswieleh AM, Anusuya Devi V, Prashanth M, Jeon BH. Facile green synthesis of samarium sesquioxide nanoparticle as a quencher for biologically active imidazole analogues: Computational and experimental insights. J Mol Struct 2022. [DOI: 10.1016/j.molstruc.2022.133235] [Citation(s) in RCA: 1] [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: 12/23/2022]
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Kemparajegowda, Swarup HA, Chandrasekhar S, Jayanna B, Kumara K, Lokanath N, Thimmaiah SB, Mantelingu K. Sulfuric acid-mediated synthesis of 2,5-disubstituted 1,3,4-thiadiazole via intramolecular cyclization reaction from dithioesters: An approach to crystal structure prediction, DFT studies and Hirshfeld surface analysis. J Mol Struct 2022. [DOI: 10.1016/j.molstruc.2021.131970] [Citation(s) in RCA: 1] [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: 12/19/2022]
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Chandrasekhar S, Pandey VL, Sahoo S. Land use and cropping decisions of agricultural households in India. Food Secur 2022. [DOI: 10.1007/s12571-021-01250-z] [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: 11/28/2022]
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Ketas TJ, Chaturbhuj D, Portillo VMC, Francomano E, Golden E, Chandrasekhar S, Debnath G, Díaz-Tapia R, Yasmeen A, Kramer KD, Munawar T, Leconet W, Zhao Z, Brouwer PJ, Cushing MM, Sanders RW, Cupo A, Klasse PJ, Formenti SC, Moore JP. Antibody Responses to SARS-CoV-2 mRNA Vaccines Are Detectable in Saliva. Pathog Immun 2021; 6:116-134. [PMID: 34136730 PMCID: PMC8201795 DOI: 10.20411/pai.v6i1.441] [Citation(s) in RCA: 90] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 05/13/2021] [Indexed: 12/14/2022] Open
Abstract
The approved Pfizer and Moderna mRNA vaccines are well known to induce serum antibody responses to the SARS-CoV-2 Spike (S)-protein. However, their abilities to elicit mucosal immune responses have not been reported. Saliva antibodies represent mucosal responses that may be relevant to how mRNA vaccines prevent oral and nasal SARS-CoV-2 transmission. Here, we describe the outcome of a cross-sectional study on a healthcare worker cohort (WELCOME-NYPH), in which we assessed whether IgM, IgG, and IgA antibodies to the S-protein and its receptor-binding domain (RBD) were present in serum and saliva samples. Anti-S-protein IgG was detected in 14/31 and 66/66 of saliva samples from uninfected participants after vaccine doses-1 and -2, respectively. IgA antibodies to the S-protein were present in 40/66 saliva samples after dose 2. Anti-S-protein IgG was present in every serum sample from recipients of 2 vaccine doses. Vaccine-induced antibodies against the RBD were also frequently present in saliva and sera. These findings may help our understanding of whether and how vaccines may impede SARS-CoV-2 transmission, including to oral cavity target cells.
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Affiliation(s)
- Thomas J. Ketas
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, New York
- TJK and DC made equal contributions to this paper
| | - Devidas Chaturbhuj
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, New York
- TJK and DC made equal contributions to this paper
| | | | - Erik Francomano
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, New York
| | - Encouse Golden
- Department of Radiation Oncology, Weill Cornell Medicine, New York, New York
| | | | - Gargi Debnath
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, New York
| | - Randy Díaz-Tapia
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, New York
| | - Anila Yasmeen
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, New York
| | - Kyle D. Kramer
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, New York
| | - Tarek Munawar
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, New York
| | - Wilhelm Leconet
- Department of Urology, Weill Cornell Medicine, New York, New York
| | - Zhen Zhao
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, New York
| | - Philip J.M. Brouwer
- Department of Medical Microbiology and Infection Prevention, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam Infection & Immunity Institute, Amsterdam, the Netherlands
| | - Melissa M. Cushing
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, New York
| | - Rogier W. Sanders
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, New York
- Department of Medical Microbiology and Infection Prevention, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam Infection & Immunity Institute, Amsterdam, the Netherlands
| | - Albert Cupo
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, New York
| | - Per Johan Klasse
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, New York
| | | | - John P. Moore
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, New York
- Current address: Antibody Research & Technology, Genmab Inc
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Ketas TJ, Chaturbhuj D, Cruz-Portillo VM, Francomano E, Golden E, Chandrasekhar S, Debnath G, Diaz-Tapia R, Yasmeen A, Leconet W, Zhao Z, Brouwer PJ, Cushing MM, Sanders RW, Cupo A, Klasse PJ, Formenti SC, Moore JP. Antibody responses to SARS-CoV-2 mRNA vaccines are detectable in saliva. bioRxiv 2021:2021.03.11.434841. [PMID: 33758842 PMCID: PMC7987001 DOI: 10.1101/2021.03.11.434841] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Vaccines are critical for curtailing the COVID-19 pandemic (1, 2). In the USA, two highly protective mRNA vaccines are available: BNT162b2 from Pfizer/BioNTech and mRNA-1273 from Moderna (3, 4). These vaccines induce antibodies to the SARS-CoV-2 S-protein, including neutralizing antibodies (NAbs) predominantly directed against the Receptor Binding Domain (RBD) (1-4). Serum NAbs are induced at modest levels within ~1 week of the first dose, but their titers are strongly boosted by a second dose at 3 (BNT162b2) or 4 weeks (mRNA-1273) (3, 4). SARS-CoV-2 is most commonly transmitted nasally or orally and infects cells in the mucosae of the respiratory and to some extent also the gastrointestinal tract (5). Although serum NAbs may be a correlate of protection against COVID-19, mucosal antibodies might directly prevent or limit virus acquisition by the nasal, oral and conjunctival routes (5). Whether the mRNA vaccines induce mucosal immunity has not been studied. Here, we report that antibodies to the S-protein and its RBD are present in saliva samples from mRNA-vaccinated healthcare workers (HCW). Within 1-2 weeks after their second dose, 37/37 and 8/8 recipients of the Pfizer and Moderna vaccines, respectively, had S-protein IgG antibodies in their saliva, while IgA was detected in a substantial proportion. These observations may be relevant to vaccine-mediated protection from SARS-CoV-2 infection and disease.
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Affiliation(s)
- Thomas J. Ketas
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY 10065
| | - Devidas Chaturbhuj
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY 10065
| | | | - Erik Francomano
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY 10065
| | - Encouse Golden
- Department of Radiation Oncology, Weill Cornell Medicine, New York, NY 10065
| | | | - Gargi Debnath
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY 10065
| | - Randy Diaz-Tapia
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY 10065
| | - Anila Yasmeen
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY 10065
| | - Wilhem Leconet
- Department of Urology, Weill Cornell Medicine, New York, NY 10065
| | - Zhen Zhao
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY 10065
| | - Philip J.M. Brouwer
- Department of Medical Microbiology and Infection Prevention, Amsterdam University Medical Centers, Location AMC, University of Amsterdam, Amsterdam Infection & Immunity Institute, 1105 AZ Amsterdam, the Netherlands
| | - Melissa M. Cushing
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY 10065
| | - Rogier W. Sanders
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY 10065
- Department of Medical Microbiology and Infection Prevention, Amsterdam University Medical Centers, Location AMC, University of Amsterdam, Amsterdam Infection & Immunity Institute, 1105 AZ Amsterdam, the Netherlands
| | - Albert Cupo
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY 10065
| | - P. J. Klasse
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY 10065
| | - Silvia C. Formenti
- Department of Radiation Oncology, Weill Cornell Medicine, New York, NY 10065
- Department of Medicine, Weill Cornell Medicine, New York, NY 10065
| | - John P. Moore
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY 10065
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Pradeep Kumar CB, Prathibha BS, Prasad KNN, Raghu MS, Prashanth MK, Jayanna BK, Alharthi FA, Chandrasekhar S, Revanasiddappa HD, Yogesh Kumar K. Click synthesis of 1,2,3-triazole based imidazoles: Antitubercular evaluation, molecular docking and HSA binding studies. Bioorg Med Chem Lett 2021; 36:127810. [PMID: 33482292 DOI: 10.1016/j.bmcl.2021.127810] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [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: 11/20/2020] [Revised: 01/06/2021] [Accepted: 01/15/2021] [Indexed: 01/27/2023]
Abstract
Using Cu(I)-catalyzed cycloaddition of alkyne and azide reaction (CuAAC), a series of novel 1,2,3-triazole based imidazole derivatives (3a-e) have been synthesized. The synthesized molecules were characterized by spectroscopic techniques such as 1H NMR, 13C NMR, mass and elemental analysis. Antitubercular activity (anti-TB) against Mycobacterium tuberculosis H37Rv (Mtb) and cytotoxic activity against the mammalian Vero cell line was screened for the synthesized compounds. The compounds 3d and 3e displayed potent in vitro antitubercular activity and may serve as a lead for further optimization. Besides, the experimental findings were in line with the results of molecular docking. Also, the synthesized compounds have also been analyzed for ADME properties and the experimental finding facilitates the development of new and more potent anti-TB agents in this series in the future. Using fluorescence and UV-vis absorption spectroscopy, the binding interaction of compounds (3d and 3e) with human serum albumin (HSA) was investigated. The results showed that, as a result of HSA-compound complex, the fluorescence quenching of HSA by test compounds was a static quenching process. According to Forster's theory, energy transfer efficiency is calculated.
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Affiliation(s)
- C B Pradeep Kumar
- Department of Chemistry, Malnad College of Engineering, Hassan 573 202, India
| | - B S Prathibha
- Department of Chemistry, B N M Institute of Technology, Bengaluru 560 070, India
| | - K N N Prasad
- Department of Physics, B N M Institute of Technology, Bengaluru 560 070, India
| | - M S Raghu
- Department of Chemistry, New Horizon College of Engineering, Bengaluru 560 103, India
| | - M K Prashanth
- Department of Chemistry, B N M Institute of Technology, Bengaluru 560 070, India.
| | - B K Jayanna
- Department of Chemistry, B N M Institute of Technology, Bengaluru 560 070, India
| | - Fahad A Alharthi
- Department of Chemistry, College of Science, King Saud University, Riyadh 11451, Saudi Arabia
| | - S Chandrasekhar
- Department of Physics, B N M Institute of Technology, Bengaluru 560 070, India
| | - H D Revanasiddappa
- Department of Studies in Chemistry, University of Mysore, Manasagangotri, Mysore 570 006, India
| | - K Yogesh Kumar
- Department of Chemistry, School of Engineering and Technology, Jain University, Ramanagara 562 112, India
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Kumar CBP, Raghu MS, Prasad KNN, Chandrasekhar S, Jayanna BK, Alharthi FA, Prashanth MK, Kumar KY. Investigation of biological activity of 2,3-disubstituted quinazolin-4(1H)-ones against Mycobacterium tuberculosis and DNA via docking, spectroscopy and DFT studies. NEW J CHEM 2021. [DOI: 10.1039/d0nj03800h] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Docking studies, structural data of DNA binding and molecular dynamics simulations of substituted quinazolin-4(1H)-ones.
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Affiliation(s)
| | - M. S. Raghu
- Department of Chemistry
- New Horizon College of Engineering
- Bengaluru 560 103
- India
| | - K. N. N. Prasad
- Department of Physics
- B N M Institute of Technology
- Bengaluru-560 070
- India
| | - S. Chandrasekhar
- Department of Physics
- B N M Institute of Technology
- Bengaluru-560 070
- India
| | - B. K. Jayanna
- Department of Chemistry
- B N M Institute of Technology
- Bengaluru-560 070
- India
| | - Fahad A. Alharthi
- Department of Chemistry
- College of Science
- King Saud University
- Riyadh
- Saudi Arabia
| | - M. K. Prashanth
- Department of Chemistry
- B N M Institute of Technology
- Bengaluru-560 070
- India
| | - K. Yogesh Kumar
- Department of Chemistry
- School of Engineering and Technology
- Jain University
- Ramanagara
- India
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Bhatt V, Chandrasekhar S, Sharma A. Regional Patterns and Determinants of Commuting Between Rural and Urban India. Indian J Labour Econ 2020; 63:1041-1063. [PMID: 33078050 PMCID: PMC7556613 DOI: 10.1007/s41027-020-00276-9] [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] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Despite an increase in the number of workers commuting between rural and urban areas, much of the literature on worker mobility continues to be migration centric. This paper establishes the importance of rural-urban commuting in India. As per estimates from Periodic Labour Force Survey 2018-2019, an estimated 18.8 million individuals living in rural are working in urban India and the share of earnings from urban in total non-farm rural earnings is 19.3%. Among all rural workers, 7.3% are rural-urban commuters while only 2.1% of urban workers are urban-rural commuters. We document large variations at the sub-national level. Our results from a multinomial model to understand the factors associated with commuting highlight the importance of lagged regional unemployment rate. A high rural unemployment rate acts as a push factor, and a low urban unemployment rate acts as a pull factor for rural-urban commuting. The urbanness of occupations in a region is also an important correlate of commuting. The paper concludes by highlighting the need to prioritize questions in India's labour force survey that would help understand the nature of labour mobility and strength of rural-urban linkages.
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Affiliation(s)
- Vasavi Bhatt
- Indira Gandhi Institute of Development Research, Gen A K VaidyaMarg, Goregaon (East), Mumbai, 400065 India
| | - S. Chandrasekhar
- Indira Gandhi Institute of Development Research, Gen A K VaidyaMarg, Goregaon (East), Mumbai, 400065 India
| | - Ajay Sharma
- Indian Institute of Management, Indore, India
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Rampalli S, Dundi TM, Chandrasekhar S, Raju VRK, Chandramohan VP. Numerical Evaluation of Liquid Mixing in a Serpentine Square Convergent-divergent Passive Micromixer. Chemical Product and Process Modeling 2020. [DOI: 10.1515/cppm-2019-0071] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [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
AbstractMicromixers are crucial components to carry out chemical, biomedical and bio-chemical analyses on µTAS (micro total analysis system) or Lab-on-chips. Simple planar type passive mixers are always most desirable over three dimensional or complex geometries of passive mixers or active mixers as they are less expensive, easy to fabricate, and easy to integrate into complex miniaturized systems. However, at very low Reynolds numbers (0 to 100), due to the inherent laminar nature of the microfluidic flows, mixing remains challenging in passive mixers. Previous studies reported that serpentine square-wave micromixer is one of the simple and effective passive device for micromixing. In the present study, to further enhance the mixing efficiency of the device, horizontal straight portions of serpentine square wave mixer are replaced with convergent-divergent passages and the mixing performance of both mixers are evaluated in the Re range of 0 to 100. It is observed in the low Re (0 to 10), mixing in the square wave mixer with convergent-divergent portions (SQW-CD mixer) is governed completely by pure diffusion as in the case of square wave mixer with straight horizontal portions (SQW mixer). However, at high Re (Re > 10), the presence of convergent-divergent portions in the SQW-CD mixer considerably intensify the stretching and folding of samples in the mixing channel. Additionally, the extra recess available at the bends of SQW-CD mixer creates recirculation zones in the mixer. Therefore, a significant improvement in the mixing performance is achieved at high Re (Re > 10) for SQW-CD mixer as compared to conventional SQW mixer. This would allow shorter mixing lengths for SQW-CD mixer as compared to Sq wave mixer. However, with increase in Re, the rise in pressure drop is considerably high for SQW-CD mixer as compared to SQW mixer.
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Affiliation(s)
- Shasidhar Rampalli
- Mechanical Engineering Department, National Institute of Technology Warangal, Warangal, Telangana 506004, India
| | - T. Manoj Dundi
- Mechanical Engineering Department, National Institute of Technology Warangal, Warangal, Telangana 506004, India
| | - S. Chandrasekhar
- Mechanical Engineering Department, National Institute of Technology Warangal, Warangal, Telangana 506004, India
| | - V. R. K. Raju
- Mechanical Engineering Department, National Institute of Technology Warangal, Warangal, Telangana 506004, India
| | - V. P. Chandramohan
- Mechanical Engineering Department, National Institute of Technology Warangal, Warangal, Telangana 506004, India
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Affiliation(s)
- Lahu N. Chavan
- Department of Organic Synthesis and Process Chemistry; CSIR-Indian Institute of Chemical Technology; 500007 Hyderabad India
- Academy of Scientific and Innovative Research (AcSIR); 201 002 Uttar Pradesh Ghaziabad India
| | - Prathama S. Mainkar
- Department of Organic Synthesis and Process Chemistry; CSIR-Indian Institute of Chemical Technology; 500007 Hyderabad India
- Academy of Scientific and Innovative Research (AcSIR); 201 002 Uttar Pradesh Ghaziabad India
| | - S. Chandrasekhar
- Department of Organic Synthesis and Process Chemistry; CSIR-Indian Institute of Chemical Technology; 500007 Hyderabad India
- Academy of Scientific and Innovative Research (AcSIR); 201 002 Uttar Pradesh Ghaziabad India
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Chandrasekhar S, Sahoo S. Land-holding, participation in agriculture and short-term migration in rural India. Asian Population Studies 2019. [DOI: 10.1080/17441730.2019.1600324] [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: 10/26/2022]
Affiliation(s)
| | - Soham Sahoo
- Centre for Public Policy, Indian Institute of Management, Bangalore, India
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Chandrasekhar S, Aguayo VM, Krishna V, Nair R. Household food insecurity and children's dietary diversity and nutrition in India. Evidence from the comprehensive nutrition survey in Maharashtra. Matern Child Nutr 2018; 13 Suppl 2. [PMID: 29032621 DOI: 10.1111/mcn.12447] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 01/30/2017] [Accepted: 02/08/2017] [Indexed: 11/27/2022]
Abstract
We analyse data from the 2012 Comprehensive Nutrition Survey in the State of Maharashtra, India, which surveyed 2,630 households. This is a unique dataset because in addition to nutritional status of mothers and children, it has information on diets of women and children and household food security. This rich dataset allows us to address three issues: whether household food security predicts higher diet diversity in children aged 6-23 months; whether household food security predicts lower risk of undernutrition; and whether the lower risk of undernutrition in children who live in food secure households is mediated by improved diet diversity for children. We find that children from moderately food insecure and severely food insecure households are more likely to have lower diet diversity scores. We find that the odds of a child being severely stunted, severely underweight, or severely wasted are higher in severely food insecure households. After controlling for children's diet diversity, and other child, maternal and household characteristics, we find that household food security is no longer statistically associated with stunting, wasting, or underweight. However, diet diversity of children is statistically significantly associated with whether a child is stunted or underweight. Our results although not causal provide evidence for understanding the extent to which household food insecurity affects children's diet diversity and how both these factors affect nutrition outcomes in children. Our analysis informs Government of Maharashtra's and India's National Nutrition Mission in their efforts for formulating appropriate policies and programmes to address child undernutrition.
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Affiliation(s)
- S Chandrasekhar
- Indira Gandhi Institute of Development Research, General A K Vaidya Marg, Goregaon (E), Mumbai, 400065, India
| | | | - Vandana Krishna
- Indian Administrative Service, Government of Maharashtra, Mumbai, India
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Chandrasekhar S, Laxminarayana G, Chakrapani Y. Novel Hybrid Segmentation Techniques for Cardiac Image Processing in Remote Health Care Monitoring Systems. j med imaging hlth inform 2017. [DOI: 10.1166/jmihi.2017.2202] [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: 11/23/2022]
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Hu H, Jopson RM, Gnauck AH, Randel S, Chandrasekhar S. Fiber nonlinearity mitigation of WDM-PDM QPSK/16-QAM signals using fiber-optic parametric amplifiers based multiple optical phase conjugations. Opt Express 2017; 25:1618-1628. [PMID: 29519016 DOI: 10.1364/oe.25.001618] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
We demonstrate fiber nonlinearity mitigation by using multiple optical phase conjugations (OPCs) in the WDM transmission systems of both 8 × 32-Gbaud PDM QPSK channels and 8 × 32-Gbaud PDM 16-QAM channels, showing improved performance over a single mid-span OPC and no OPC in terms of nonlinear threshold and a best achievable Q2 factor after transmission. In addition, after an even number of OPCs, the signal wavelength can be preserved after transmission. The performance of multiple OPCs for fiber nonlinearity mitigation was evaluated independently for WDM PDM QPSK signals and WDM PDM 16-QAM signals. The technique of multiple OPCs is proved to be transparent to modulation formats and effective for different transmission links. In the WDM PDM QPSK transmission system over 3600 km, by using multiple OPCs the nonlinear threshold (i.e. optimal signal launched power) was increased by ~5 dB compared to the case of no OPC and increased by ~2 dB compared to the case of mid-span OPC. In the WDM PDM 16-QAM transmission system over 912 km, by using the multiple OPCs the nonlinear threshold was increased by ~7 dB compared to the case of no OPC and increased by ~1 dB compared to the case of mid-span OPC. The improvements in the best achievable Q2 factors were more modest, ranging from 0.2 dB to 1.1 dB for the results presented.
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Formenti SC, Golden EB, Goldberg JD, Li X, Taff J, Fenton-Kerimian MB, Chandrasekhar S, Demaria S, Novik Y. Results of a phase I-II study of adjuvant concurrent carboplatin and accelerated radiotherapy for triple negative breast cancer. Oncoimmunology 2016; 6:e1274479. [PMID: 28405497 DOI: 10.1080/2162402x.2016.1274479] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 12/12/2016] [Accepted: 12/14/2016] [Indexed: 12/31/2022] Open
Abstract
Purpose: To determine feasibility and explore the clinical efficacy of concurrent radiotherapy and carboplatin as adjuvant treatment of triple negative breast cancer (TNBC). Patients and Methods: Women with Stage I-II TNBC were treated after surgery in a phase I-II prospective trial [NCT01289353]. Weekly carboplatin (AUC = 2.0) was delivered for 6 weeks. Concurrent radiotherapy was delivered in the prone position during weeks 2-4, for a total dose of 40.5 Gy in 15 fractions to the breast, and 46.5 Gy in 17 fractions to the tumor bed. Adverse events (AE) were assessed weekly during treatment, once at 45-60 d, and every 6 mo thereafter, using the Common Terminology Criteria for AE (CTCAE) v3.0. Results: A total of 39 patients accrued and 36 received treatment. Eight patients (22%, exact 95% CI: 10%, 39%) developed grade 2 or greater acute radiation dermatitis. Overall, grade 2 AE were seen in nine and grade 3 in two patients. Twenty-three patients (64%) received additional adjuvant chemotherapy. With a median follow-up of 48 mo, 34/36 (94%) are alive and disease free. One patient died of pulmonary failure with possible but unproven breast cancer recurrence, and one patient died of pelvic malignancy. One patient recurred locally and is alive and disease free after surgical management. Brisk lymphocytic infiltrate was present pre-treatment in 39% of 18 patients with evaluable tumor. Conclusions: Adjuvant concurrent carboplatin and prone accelerated radiotherapy is a well-tolerated and promising treatment of early stage TNBC. The observed 3% compares favorably with the expected 30% recurrence rate within 1-4 y from treatment, warranting further studies.
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Affiliation(s)
- Silvia C Formenti
- Department of Radiation Oncology, Weill Cornell Medicine , New York, NY, USA
| | - Encouse B Golden
- Department of Radiation Oncology, Weill Cornell Medicine , New York, NY, USA
| | - Judith D Goldberg
- Departments of Population Health and Environmental Medicine, New York University School of Medicine , New York, NY, USA
| | - Xiaochun Li
- Departments of Population Health and Environmental Medicine, New York University School of Medicine , New York, NY, USA
| | - Jessica Taff
- Department of Medicine, New York University School of Medicine , New York, NY, USA
| | | | | | - Sandra Demaria
- Department of Radiation Oncology, Weill Cornell Medicine , New York, NY, USA
| | - Yelena Novik
- Department of Medicine, New York University School of Medicine , New York, NY, USA
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Rajagopalan S, Suresh M, Clark SL, Serratos B, Chandrasekhar S. Airway management for cesarean delivery performed under general anesthesia. Int J Obstet Anesth 2016; 29:64-69. [PMID: 27884665 DOI: 10.1016/j.ijoa.2016.10.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2016] [Revised: 09/29/2016] [Accepted: 10/20/2016] [Indexed: 11/19/2022]
Abstract
BACKGROUND With the increasing popularity of neuraxial anesthesia, there has been a decline in the use of general anesthesia for cesarean delivery. We sought to examine the incidence, outcome and characteristics associated with a failed airway in patients undergoing cesarean delivery under general anesthesia. METHODS A retrospective review of airway management in women undergoing cesarean delivery under general anesthesia over an eight-year period from 2006-2013 at an academic medical center was conducted. RESULTS During the study period, 10 077 cesarean deliveries were performed. Neuraxial anesthesia was used in 9382 (93%) women while general anesthesia was used in 695 (7%). Emergent cesarean delivery was the most common indication for general anesthesia. Failed intubation was encountered in only three (0.4%) women, who were successfully managed with a laryngeal mask airway. The overall incidence of failed intubation was 1 in 232 (95% CI 1:83 to 1:666) and general anesthesia was continued in all cases. There were no adverse maternal or fetal outcomes directly related to failed intubation. CONCLUSION Advances in adjunct airway equipment, availability of an experienced anesthesiologist and simulation-based teaching of failed airway management in obstetrics may have contributed to our improved maternal outcomes in patients undergoing cesarean delivery under general anesthesia.
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Affiliation(s)
- S Rajagopalan
- Department of Anesthesiology, Baylor College of Medicine, Houston, TX, USA.
| | - M Suresh
- Department of Anesthesiology, Baylor College of Medicine, Houston, TX, USA
| | - S L Clark
- Department of Obstetrics and Gynecology, Maternal Fetal Medicine, Baylor College of Medicine, Houston, TX, USA
| | - B Serratos
- Department of Anesthesiology, Baylor College of Medicine, Houston, TX, USA
| | - S Chandrasekhar
- Department of Anesthesiology, Baylor College of Medicine, Houston, TX, USA
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Dong P, Chen X, Kim K, Chandrasekhar S, Chen YK, Sinsky JH. 128-Gb/s 100-km transmission with direct detection using silicon photonic Stokes vector receiver and I/Q modulator. Opt Express 2016; 24:14208-14214. [PMID: 27410578 DOI: 10.1364/oe.24.014208] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Recently, there is increasing interest in utilizing Stokes vector receiver, which is a direct-detection technique with the capability to digitally track the polarization changes in fibers and decode information in multiple dimensions. Here, we report a monolithically integrated silicon photonic Stokes vector receiver, which consists of one polarization beam splitter, two polarization rotators, one 90-degree optical hybrid, and six germanium photodetectors. Paired with a silicon in-phase/quadrature modulator incorporating a power-tunable carrier in the orthogonal polarization, transmission at 128-Gb/s over 100-km fiber is achieved with direct detection.
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Chandrasekhar S, Harvey AK, Yu XP, Chambers MG, Oskins JL, Lin C, Seng TW, Thibodeaux SJ, Norman BH, Hughes NE, Schiffler MA, Fisher MJ. Identification and Characterization of Novel Microsomal Prostaglandin E Synthase-1 Inhibitors for Analgesia. ACTA ACUST UNITED AC 2016; 356:635-44. [DOI: 10.1124/jpet.115.228932] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 01/05/2016] [Indexed: 01/30/2023]
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Marom DM, Dunayevsky J, Sinefeld D, Blau M, Ryf R, Fontaine NK, Montoliu M, Randel S, Liu C, Ercan B, Esmaeelpour M, Chandrasekhar S, Gnauck AH, Leon-Saval SG, Bland-Hawthorn J, Salazar-Gil JR, Sun Y, Grüner-Nielsen L, Lingle R. Wavelength-selective switch with direct few mode fiber integration. Opt Express 2015; 23:5723-5737. [PMID: 25836802 DOI: 10.1364/oe.23.005723] [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] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The first realization of a wavelength-selective switch (WSS) with direct integration of few mode fibers (FMF) is fully described. The free-space optics FMF-WSS dynamically steers spectral information-bearing beams containing three spatial modes from an input port to one of nine output ports using a phase spatial light modulator. Sources of mode dependent losses (MDL) are identified, analytically analyzed and experimentally confirmed on account of different modal sensitivities to fiber coupling in imperfect imaging and at spectral channel edges due to mode clipping. These performance impacting effects can be reduced by adhering to provided design guidelines, which scale in support of higher spatial mode counts. The effect on data transmission of cascaded passband filtering and MDL build-up is experimentally investigated in detail.
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Rajagopalan S, Nwazota N, Chandrasekhar S. Outcomes in pregnant women with acute aortic dissections: a review of the literature from 2003 to 2013. Int J Obstet Anesth 2014; 23:348-56. [PMID: 25223644 DOI: 10.1016/j.ijoa.2014.05.001] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 04/07/2014] [Accepted: 05/05/2014] [Indexed: 12/24/2022]
Abstract
BACKGROUND Acute aortic dissection in pregnant women is a rare but potentially life-threatening event. Our aim was to evaluate maternal and fetal outcomes of acute aortic dissection during pregnancy. METHODS We conducted a review of literature of the PubMed database to identify publications related to pregnant women with acute aortic dissections during the period 2003-2013: 59 articles were included in the study. RESULTS A total of 75 patients were included in the analyses. Stanford type A dissections were the most common form, accounting for 77% of all cases. The majority (78%) occurred in the third trimester and immediate postpartum period. Inherited connective tissue disorders were causative in 49% of patients. Maternal mortality was not statistical different between type A and type B dissections (21% vs. 23%), but fetal outcomes were worse in type B dissections (35% vs. 10.3%; P<0.05). Fetal mortality in type A dissections was dependent on the timing of aortic repair, with antepartum aortic repair associated with a higher mortality (36%). CONCLUSION Despite advances in diagnostic and surgical techniques, maternal and fetal mortalities in pregnant patients with aortic dissection remain high. Patients undergoing combined cesarean section with aortic repair had favorable fetal outcomes.
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Affiliation(s)
- S Rajagopalan
- Department of Anesthesiology, Baylor College of Medicine, Houston, TX, USA.
| | - N Nwazota
- Department of Anesthesiology, Baylor College of Medicine, Houston, TX, USA
| | - S Chandrasekhar
- Department of Anesthesiology, Baylor College of Medicine, Houston, TX, USA
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Pal R, Mukherjee S, Chandrasekhar S, Guru Row TN. Exploring Cyclopentadienone Antiaromaticity: Charge Density Studies of Various Tetracyclones. J Phys Chem A 2014; 118:3479-89. [DOI: 10.1021/jp5010924] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Rumpa Pal
- Solid State and Structural
Chemistry Unit and ‡Organic Chemistry, Indian Institute of Science, Bangalore-560012, India
| | - Somnath Mukherjee
- Solid State and Structural
Chemistry Unit and ‡Organic Chemistry, Indian Institute of Science, Bangalore-560012, India
| | - S. Chandrasekhar
- Solid State and Structural
Chemistry Unit and ‡Organic Chemistry, Indian Institute of Science, Bangalore-560012, India
| | - T. N. Guru Row
- Solid State and Structural
Chemistry Unit and ‡Organic Chemistry, Indian Institute of Science, Bangalore-560012, India
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Liu X, Hu H, Chandrasekhar S, Jopson RM, Gnauck AH, Dinu M, Xie C, Winzer PJ. Generation of 1.024-Tb/s Nyquist-WDM phase-conjugated twin vector waves by a polarization-insensitive optical parametric amplifier for fiber-nonlinearity-tolerant transmission. Opt Express 2014; 22:6478-6485. [PMID: 24663996 DOI: 10.1364/oe.22.006478] [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: 06/03/2023]
Abstract
We experimentally demonstrate the generation of 1.024-Tb/s Nyquist-WDM phase-conjugated vector twin waves (PCTWs), consisting of eight 128-Gb/s polarization-division-multiplexed QPSK signals and their idlers, by a broadband polarization-insensitive fiber optic parametric amplifier. This novel all-optical signal processing approach to generate WDM-PCTWs enables a 2-fold reduction in the needed optical transmitters as compared to the conventional approach where each idler is generated by a dedicated transmitter. Digital coherent superposition of the twin waves at the receiver enables more than doubled reach in a dispersion-managed transmission link. We further study the impact of polarization-mode dispersion on the performance gain brought by the phase-conjugated twin waves, showing a gain of ~3.8 dB in signal quality factors.
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Xia C, Liu X, Chandrasekhar S, Fontaine NK, Zhu L, Li G. Multi-channel nonlinearity compensation of PDM-QPSK signals in dispersion-managed transmission using dispersion-folded digital backward propagation. Opt Express 2014; 22:5859-5866. [PMID: 24663923 DOI: 10.1364/oe.22.005859] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We demonstrate nonlinearity compensation of 37.5-GHz-spaced 128-Gb/s PDM-QPSK signals using dispersion-folded digital-backward-propagation and a spectrally-sliced receiver that simultaneously receives three WDM signals, showing mitigation of intra-channel and inter-channel nonlinear effects in a 2560-km dispersion-managed TWRS-fiber link. Intra-channel and adjacent inter-channel nonlinear compensation gains when WDM channels are fully populated in the C-band are estimated based on the GN-model.
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Liu X, Chandrasekhar S, Gnauck AH, Winzer PJ, Randel S, Corteselli S, Chraplyvy AR, Tkach RW, Zhu B, Taunay TF, Fishteyn M. Digital coherent superposition for performance improvement of spatially multiplexed coherent optical OFDM superchannels. Opt Express 2012; 20:B595-B600. [PMID: 23262907 DOI: 10.1364/oe.20.00b595] [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] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We demonstrate the use of digital coherent superposition to improve the performance of space-division-multiplexed (SDM) 676-Gb/s OFDM-16QAM superchannels, achieving ~4 dB improvement in OSNR by using two SDM copies and 1075-km (14 x 76.8 km) transmission over a seven-core-fiber with an effective aggregate spectral efficiency of 23.7 b/s/Hz. We further show that the performance improvement from the coherent superposition is retained in the nonlinear transmission regime through coordinated scrambling of signal constellations at the transmitter and appropriate unscrambling at the receiver, by using a series of simple scrambling functions.
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Affiliation(s)
- Xiang Liu
- Bell Labs, Alcatel-Lucent, 791 Holmdel-Keyport Road, Holmdel, New Jersey 07733, USA.
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Karunakaran JV, Kumar SS, Kumar M, Chandrasekhar S, Namitha D. The effects of various irrigating solutions on intra-radicular dentinal surface: An SEM analysis. J Pharm Bioallied Sci 2012; 4:S125-30. [PMID: 23066232 PMCID: PMC3467874 DOI: 10.4103/0975-7406.100209] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Revised: 01/02/2012] [Accepted: 01/26/2012] [Indexed: 11/06/2022] Open
Abstract
Aim: The action of irrigant solutions on intra- radicular dentinal surface were evaluated in an in vitro setting using a scanning electron microscope (SEM) and it was observed that sodium hypochlorite and MTAD produced the cleanest surface and that none of the irrigants were able to produce an ideal preparation of the dentinal surface when used individually. The primary objective of endodontic therapy is to achieve a clean, optimal environment in root canals to avoid unsuccessful treatment outcomes. The complexities of the root canal system necessitate the use of irrigating solutions which act on radicular dentin surface, modifying it. The action of irrigants can be beneficial, and yet at the same time, as they modify the surface structure of dentin, they can have an adverse impact on the properties of dentin. The present study was undertaken to assess the effect of various irrigants on the dentinal surface using an SEM. Materials and Methods: Forty-five roots were randomly divided into nine groups (n=5) and prepared by sectioning at the level of cemento-enamel junction (CEJ) and 10 mm from the CEJ and split longitudinally. The dentin surface was prepared and the cemental surfaces were coated with double layer of varnish. The irrigants tested were normal saline, de-ionized water, 17% ethylenediaminetetraacetic acid (EDTA), 5% sodium hypochlorite (NaOCl), 5% NaOCl with ultrasonic agitation, 3% hydrogen peroxide, 2% chlorhexidine (CHX), MTAD, and MTAD with ultrasonic agitation. The prepared samples were placed in the irrigant solution for 3 min, subsequently dehydrated, sputter coated, and observed under SEM. The images were subsequently analyzed for dentinal surface changes. Results: 17% EDTA and MTAD produced the cleanest dentinal surface. Ultrasonic agitation enhanced the effect of irrigants. 5% NaOCl and 3% hydrogen peroxide were efficient at removal of organic debris, but were unable to remove the smear layer. De-ionized water, normal saline, and 2% chlorhexidine were not effective at removing the debris or the smear layer. Conclusion: None of the irrigants individually were able to achieve conditions of an ideal dentinal surface preparation.
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Affiliation(s)
- J V Karunakaran
- Department of Conservative Dentistry, JKKN Dental College, Komarapalayam, Tamil Nadu, India
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Liu X, Chandrasekhar S, Winzer PJ, Chraplyvy AR, Tkach RW, Zhu B, Taunay TF, Fishteyn M, DiGiovanni DJ. Scrambled coherent superposition for enhanced optical fiber communication in the nonlinear transmission regime. Opt Express 2012; 20:19088-19095. [PMID: 23038549 DOI: 10.1364/oe.20.019088] [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] [Indexed: 06/01/2023]
Abstract
Coherent superposition of light waves has long been used in various fields of science, and recent advances in digital coherent detection and space-division multiplexing have enabled the coherent superposition of information-carrying optical signals to achieve better communication fidelity on amplified-spontaneous-noise limited communication links. However, fiber nonlinearity introduces highly correlated distortions on identical signals and diminishes the benefit of coherent superposition in nonlinear transmission regime. Here we experimentally demonstrate that through coordinated scrambling of signal constellations at the transmitter, together with appropriate unscrambling at the receiver, the full benefit of coherent superposition is retained in the nonlinear transmission regime of a space-diversity fiber link based on an innovatively engineered multi-core fiber. This scrambled coherent superposition may provide the flexibility of trading communication capacity for performance in future optical fiber networks, and may open new possibilities in high-performance and secure optical communications.
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Affiliation(s)
- Xiang Liu
- Bell Labs, Alcatel-Lucent, Holmdel, New Jersey 07733, USA.
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Chandrasekhar S, Mukhopadhyay A. MULTIPLE DIMENSIONS OF URBAN WELL-BEING. Asian Population Studies 2012. [DOI: 10.1080/17441730.2012.684537] [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: 10/28/2022]
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Chandrasekhar S. On the presumed kinetic consequences of pre-equilibrium. Implications for the Michaelis-Menten equation. Russ J Phys Chem 2012. [DOI: 10.1134/s0036024412040061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Rajiah K, Kumar A, Chandrasekhar S. Antibiotics surveillance: a survey on the susceptibility of microorganisms to antibiotics in respiratory tract infections. Eur J Hosp Pharm 2012. [DOI: 10.1136/ejhpharm-2012-000074.26] [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: 11/03/2022] Open
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Kang I, Liu X, Chandrasekhar S, Rasras M, Jung H, Cappuzzo M, Gomez LT, Chen YF, Buhl L, Cabot S, Jaques J. Energy-efficient 0.26-Tb/s coherent-optical OFDM transmission using photonic-integrated all-optical discrete Fourier transform. Opt Express 2012; 20:896-904. [PMID: 22274436 DOI: 10.1364/oe.20.000896] [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] [Indexed: 05/31/2023]
Abstract
We propose a novel energy-efficient coherent-optical OFDM transmission scheme based on hybrid optical-electronic signal processing. We demonstrate transmission of a 0.26-Tb/s OFDM superchannel, consisting of 13 x 20-Gb/s polarization-multiplexed QPSK subcarrier channels, over 400-km standard single-mode fiber (SSMF) with BER less than 6.3x10(-4) using all-optical Fourier transform processing and electronic 7-tap blind digital equalization per subchannel. We further explore long-haul transmission over up to 960 km SSMF and show that the electronic signal processing is capable of compensating chromatic dispersion up to 16,000 ps/nm using only 15 taps per subchannel, even in the presence of strong inter-carrier interference.
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Affiliation(s)
- I Kang
- Bell Laboratories, Alcatel-Lucent, Holmdel, New Jersey 07733, USA.
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Chandrasekhar S, Gnauck AH, Liu X, Winzer PJ, Pan Y, Burrows EC, Taunay TF, Zhu B, Fishteyn M, Yan MF, Fini JM, Monberg EM, Dimarcello FV. WDM/SDM transmission of 10 x 128-Gb/s PDM-QPSK over 2688-km 7-core fiber with a per-fiber net aggregate spectral-efficiency distance product of 40,320 km·b/s/Hz. Opt Express 2012; 20:706-711. [PMID: 22274415 DOI: 10.1364/oe.20.000706] [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] [Indexed: 05/31/2023]
Abstract
We demonstrate 2688-km multi-span transmission using wavelength-division multiplexing (WDM) of ten 50-GHz spaced 128-Gb/s PDM-QPSK signals, space-division multiplexed (SDM) in a low-crosstalk 76.8-km seven-core fiber, achieving a record net aggregate per-fiber-spectral-efficiency-distance product of 40,320 km·b/s/Hz. The demonstration was enabled by a novel core-to-core signal rotation scheme implemented in a 7-fold, synchronized recirculating loop apparatus.
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Liu X, Chandrasekhar S, Chen X, Winzer PJ, Pan Y, Taunay TF, Zhu B, Fishteyn M, Yan MF, Fini JM, Monberg EM, Dimarcello FV. 1.12-Tb/s 32-QAM-OFDM superchannel with 8.6-b/s/Hz intrachannel spectral efficiency and space-division multiplexed transmission with 60-b/s/Hz aggregate spectral efficiency. Opt Express 2011; 19:B958-B964. [PMID: 22274125 DOI: 10.1364/oe.19.00b958] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We demonstrate the generation of a 1.12-Tb/s superchannel based on coherent optical orthogonal frequency-division multiplexing with polarization-division multiplexed 32-QAM subcarriers, achieving a net intrachannel-spectral-efficiency (ISE) of 8.6 b/s/Hz. Using space-division multiplexing (SDM), we transmit this superchannel over a 76.8-km low-crosstalk multi-core-fiber (MCF) with a record aggregate ISE of 60 b/s/Hz per fiber. We also discuss the impact of core-to-core crosstalk on transmission performance, as well as future perspectives of MCF-based SDM transmission.
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Affiliation(s)
- Xiang Liu
- Bell Labs, Alcatel-Lucent, 791 Holmdel-Keyport Road, Holmdel, NJ 07733, USA.
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Liu X, Chandrasekhar S, Wood TH, Tkach RW, Winzer PJ, Burrows EC, Chraplyvy AR. M-ary pulse-position modulation and frequency-shift keying with additional polarization/phase modulation for high-sensitivity optical transmission. Opt Express 2011; 19:B868-B881. [PMID: 22274115 DOI: 10.1364/oe.19.00b868] [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] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We present a new class of optical modulation formats based on the combination of m-ary pulse-position modulation (m-PPM) or m-ary frequency-shift keying (FSK) with additional polarization and/or phase modulation, which is applied on the information carrying pulses in the case of m-PPM or on the information carrying frequency carriers in the case of m-FSK. We describe the principle and implementation of this class of optical modulation formats, and formulate their theoretical receiver sensitivities in optically pre-amplified receivers. Pilot-assisted frequency-domain equalization, similar to that used in coherent optical orthogonal frequency-division multiplexing (CO-OFDM), is used for reliable channel estimation and compensation. CO-OFDM also allows m-FSK to be implemented with high spectral efficiency. As a particular format in this class, m-PPM in combination with polarization-division-multiplexed quadrature phase-shift keying (PDM-QPSK), termed as PQ-mPPM, offers superior receiver sensitivity in optically pre-amplified receivers at bit error ratios (BERs) around the thresholds of common forward-error correction codes. Record receiver sensitivities of 3.5 photons per bit (ppb) at BER = 10(-3) and 2.7 ppb at BER = 1.5 × 10(-2) are experimentally demonstrated at 2.5 Gb/s and 6.23 Gb/s using PQ-16PPM and PQ-4PPM, respectively. We further demonstrate the transmission of a 6.23-Gb/s PQ-4PPM signal over a 370-km unrepeatered ultra-large-area-fiber span with 71.7-dB total loss budget.
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Affiliation(s)
- Xiang Liu
- Bell Labs, Alcatel-Lucent, 791 Holmdel-Keyport Road, Holmdel, NJ 07733, USA.
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Youn CJ, Liu X, Chandrasekhar S, Kwon YH, Kim JH, Choe JS, Kim DJ, Choi KS, Nam ES. Channel estimation and synchronization for polarization-division multiplexed CO-OFDM using subcarrier/polarization interleaved training symbols. Opt Express 2011; 19:16174-16181. [PMID: 21934980 DOI: 10.1364/oe.19.016174] [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] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We propose and demonstrate the use of subcarrier/polarization-interleaved training symbols for channel estimation and synchronization in polarization-division multiplexed (PDM) coherent optical orthogonal frequency-division multiplexed (CO-OFDM) transmission. The principle, the computational efficiency, and the frequency-offset tolerance of the proposed method are described. We show that the use of subcarrier/polarization interleaving doubles the tolerance to the frequency offset between the transmit laser and the receiver's optical local oscillator as compared to conventional schemes. Using this method, we demonstrate 43-Gb/s PDM CO-OFDM transmission with 16-QAM subcarrier modulation over 5,200-km of ultra-large-area fiber.
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Affiliation(s)
- Chun Ju Youn
- Photonic/Wireless Convergence Component Department, Electronics and Telecommunications Research Institute 138 Gajeongno, Yuseong-gu, Daejeon, 305-700, Korea.
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Zhu B, Taunay TF, Fishteyn M, Liu X, Chandrasekhar S, Yan MF, Fini JM, Monberg EM, Dimarcello FV. 112-Tb/s space-division multiplexed DWDM transmission with 14-b/s/Hz aggregate spectral efficiency over a 76.8-km seven-core fiber. Opt Express 2011; 19:16665-16671. [PMID: 21935028 DOI: 10.1364/oe.19.016665] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We describe a new multicore fiber (MCF) having seven single-mode cores arranged in a hexagonal array, exhibiting low crosstalk among the cores and low loss across the C and L bands. We experimentally demonstrate a record transmission capacity of 112 Tb/s over a 76.8-km MCF using space-division multiplexing and dense wavelength-division multiplexing (DWDM). Each core carries 160 107-Gb/s polarization-division multiplexed quadrature phase-shift keying (PDM-QPSK) channels on a 50-GHz grid in the C and L bands, resulting in an aggregate spectral efficiency of 14 b/s/Hz. We further investigate the impact of the inter-core crosstalk on a 107-Gb/s PDM-QPSK signal after transmitting through the center core of the MCF when all the 6 outer cores carry same-wavelength 107-Gb/s signals with equal powers, and discuss the system implications of core-to-core crosstalk on ultra-long-haul transmission.
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Affiliation(s)
- B Zhu
- OFS Labs, 19 Schoolhouse Rd, Somerset NJ, 08873, USA.
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Kang I, Rasras M, Liu X, Chandrasekhar S, Cappuzzo M, Gomez LT, Chen YF, Buhl L, Cabot S, Jaques J. All-optical OFDM transmission of 7 x 5-Gb/s data over 84-km standard single-mode fiber without dispersion compensation and time gating using a photonic-integrated optical DFT device. Opt Express 2011; 19:9111-9117. [PMID: 21643165 DOI: 10.1364/oe.19.009111] [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] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We implement dispersion-tolerant and time-gating-free all-optical OFDM transmission using a photonic-integrated discrete Fourier transform (DFT) device. We show that 35-Gb/s OFDM data having near-unity spectral efficiency can be transmitted all-optically with 1-dB dispersion margin of ~1000 ps/nm. The passive-optical DFT circuit is implemented using multi-mode interference (MMI) couplers on a high index-contrast silica integrated-optic platform. We also propose a photonic DFT circuit based on an NxN MMI device capable of simultaneous channelization of OFDM signals into N subcarriers.
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Affiliation(s)
- I Kang
- Bell Laboratories, Alcatel-Lucent, 791 Holmdel-Keyport Road, Holmdel, New Jersey 07733, USA.
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Raju B, Ramesh M, Srinivas R, Chandrasekhar S, Kiranmai N, Sarma VUM. Differentiation of positional isomers of hybrid peptides containing repeats of β-nucleoside derived amino acid (β-Nda-) and L-amino acids by positive and negative ion electrospray ionization tandem mass spectrometry (ESI-MSn). J Am Soc Mass Spectrom 2011; 22:703-717. [PMID: 21472609 DOI: 10.1007/s13361-010-0070-z] [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] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2010] [Revised: 11/19/2010] [Accepted: 12/26/2010] [Indexed: 05/30/2023]
Abstract
A new class of positional isomeric pairs of -Boc protected oligopeptides comprised of alternating nucleoside derived β-amino acid (β-Nda-) and L-amino acid residues (alanine, valine, and phenylalanine) have been differentiated by both positive and negative ion electrospray ionization ion-trap tandem mass spectrometry (ESI-MS(n)). The protonated dipeptide positional isomers with β-Nda- at the N-terminus lose CH(3)OH, NH(3), and C(2)H(4)O(2), whereas these processes are absent for the peptides with L-amino acids at the N-terminus. Instead, the presence of L-amino acids at the N-terminus results in characteristic retro-Mannich reaction involving elimination of imine. A good correlation has been observed between the conformational structure of the peptides and the abundance of y(n)(+) and b(n)(+) ions in MS(n) spectra. In the case of tetrapeptide isomers that are reported to form helical structures in solution phase, no y(n)(+) and b(n)(+) ions are observed when the corresponding amide -NH- participates in the helical structures. In contrast, significant y(n)(+) and b(n)(+) ions are formed when the amide -NH- is not involved in the H-bonding. In the case of tetra- and hexapeptides, it is observed that abundant b(n)(+) ions are formed, presumably with stable oxazolone structures when the C-terminus of the b(n)(+) ions possessed L-amino acid and the β-Nda- at the C-terminus appears to prevent the cyclization process leading to the absence of corresponding b(n)(+) ions.
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Affiliation(s)
- B Raju
- National Center for Mass Spectrometry, Indian Institute of Chemical Technology, Hyderabad, 500607 India
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Chandrasekhar S, Prakash SJ, Shyamsunder T, Ramachandar T. Tantalum (V) Chloride Catalyzed Ring Opening of Aziridines with Aromatic Amines. SYNTHETIC COMMUN 2011. [DOI: 10.1081/scc-200034759] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- S. Chandrasekhar
- a Indian Institute of Chemical Technology , Hyderabad, 500 007, India
| | - S. Jaya Prakash
- a Indian Institute of Chemical Technology , Hyderabad, 500 007, India
| | - T. Shyamsunder
- a Indian Institute of Chemical Technology , Hyderabad, 500 007, India
| | - T. Ramachandar
- a Indian Institute of Chemical Technology , Hyderabad, 500 007, India
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Swearingen CA, Chambers MG, Lin C, Marimuthu J, Rito CJ, Carter QL, Dotzlaf J, Liu C, Chandrasekhar S, Duffin KL, Mitchell PG, Durham TB, Wiley MR, Thirunavukkarasu K. A short-term pharmacodynamic model for monitoring aggrecanase activity: injection of monosodium iodoacetate (MIA) in rats and assessment of aggrecan neoepitope release in synovial fluid using novel ELISAs. Osteoarthritis Cartilage 2010; 18:1159-66. [PMID: 20633676 DOI: 10.1016/j.joca.2010.02.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2009] [Revised: 01/27/2010] [Accepted: 02/06/2010] [Indexed: 02/02/2023]
Abstract
OBJECTIVE To develop a short-term in vivo model in rats, with an enzyme-linked immunosorbent assay (ELISA) readout for specific aggrecanase-cleaved aggrecan fragments, to facilitate testing of aggrecanase inhibitors. METHODS Monosodium iodoacetate (MIA), a metabolic inhibitor, was injected into the right knee joint of male Lewis rats and the release of aggrecanase-cleaved fragments of aggrecan containing the NITEGE or ARGN neoepitope was measured in the synovial fluid at 7 days post MIA injection using novel ELISAs. The ELISAs utilize a commercial antibody directed against the hyaluronic-acid binding region (HABR) of aggrecan, in combination with either an alpha-NITEGE antibody (NITEGE ELISA) or an alpha-ARGS/BC3 antibody (ARGS ELISA), to detect aggrecanase-cleavage of aggrecan within the interglobular domain (IGD). Aggrecan fragments present in in vitro digests, in cytokine-treated cartilage explant culture supernatants and in rat synovial fluid lavage samples were detected and quantified using the two ELISAs. Small molecule inhibitors of aggrecanase activity were dosed orally on days 3-7 to determine their ability to inhibit MIA-induced generation of the NITEGE and ARGN neoepitopes measured in the rat synovial fluid. RESULTS The NITEGE assay was shown to specifically detect the N-terminal fragment of aggrecan comprising the G1 domain and the NITEGE neoepitope sequence. This assay can readily measure aggrecanase-cleaved bovine, human and rat aggrecan without the need for deglycosylation. The ARGS assay specifically detects C-terminal fragments of aggrecan comprising the ARGS/ARGN neoepitope and the G2 domain. Keratan sulfate (KS) residues of aggrecan interfere with this ELISA, and hence this assay works well with native rat articular cartilage aggrecan (that lacks KS residues) and with deglycosylated bovine and human aggrecan. Injection of MIA into the rat knee joints resulted in a time-dependent increase in the release of aggrecanase-cleaved aggrecan fragments into the synovial fluid and treatment with an aggrecanase inhibitor resulted in a dose-dependent inhibition of the generation of these neoepitopes. CONCLUSIONS We have established a short-term in vivo model in rats that involves measurement of synovial fluid biomarkers that are dependent on aggrecanase activity in the joint. The short duration of the model combined with the mechanistic biomarker readout makes it very useful for the initial in vivo screening of aggrecanase inhibitors prior to testing them in time and resource-intensive disease models of osteoarthritis (OA).
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Affiliation(s)
- C A Swearingen
- Musculoskeletal Research, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285, USA
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Chandrasekhar S, Kiranmai N. Asymmetric total synthesis of (+)-cardiobutanolide via an iterative asymmetric dihydroxylation in PEG. Tetrahedron Lett 2010. [DOI: 10.1016/j.tetlet.2010.05.122] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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