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Rajput S, Kaushik V, Babu P, Pandey SK, Kumar M. All optical modulation in vertically coupled indium tin oxide ring resonator employing epsilon near zero state. Sci Rep 2023; 13:18379. [PMID: 37884529 PMCID: PMC10603087 DOI: 10.1038/s41598-023-44438-3] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 10/08/2023] [Indexed: 10/28/2023] Open
Abstract
We present an innovative approach to achieve all-optical modulation within an ITO-based vertically coupled ring resonator. This method leverages the material's enhanced nonlinear response in the near-infrared wavelengths, particularly within the epsilon-near-zero (ENZ) state. To enhance the interaction between light and the material while minimizing scattering losses, our approach employs an ITO-based vertically connected ring resonator. The vertical arrangement eliminates the need for etching fine gaps to separate the ring and bus waveguide. The novel waveguide design addresses the necessity of high sensitivity, non-linear effects and compact size opening the possibilities for all-optical signal processing. This unique resonator structure effectively facilitates the coupling of a high-intensity pump wavelength into the ITO-based micro-ring resonator. Consequently, this optical pumping induces electron heating within the ITO material, leading to a significant increase in its nonlinear optical properties. This, in turn, results in a noteworthy alteration of ITO's refractive index, specifically in the unity order, thereby modifying the complex effective index of the optical beam propagating at 1550 nm. Our experimental findings demonstrate an impressive extinction ratio of 18 dB for a 30 µm long device, which highlights the efficiency of our approach in achieving all-optical modulation through the optical pumping of an ITO-based vertically coupled ring resonator. The proposed all-optical modulator has outperformed as compared to conventional waveguide-based modulators in terms of extinction ratio and footprint. This novel technique holds immense potential for advancing high-speed data communication systems in the future. As the demand for advanced processing capabilities, such as artificial intelligence, continues to grow, all-optical modulation emerges as a groundbreaking technology poised to revolutionize the next generation of computing and communication systems.
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Affiliation(s)
- Swati Rajput
- Department of Electrical Engineering, Indian Institute of Technology (IIT) Jodhpur, Jodhpur, India.
| | - Vishal Kaushik
- School of Electrical Engineering, Tel Aviv University, Tel Aviv, Israel
| | - Prem Babu
- Department of Electrical Engineering, Indian Institute of Technology (IIT) Indore, Indore, India
| | - Suresh K Pandey
- Department of Electrical Engineering, Indian Institute of Technology (IIT) Indore, Indore, India
| | - Mukesh Kumar
- Department of Electrical Engineering, Indian Institute of Technology (IIT) Indore, Indore, India
- Center of Advanced Electronics, Indian Institute of Technology (IIT) Indore, Indore, India
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Bakthavatchalam Y, Vasudevan K, Babu P, Munusamy E, Veeraraghavan B. High-risk ST772-MRSA lineage in South Asia: potential for global dissemination. Int J Infect Dis 2020. [DOI: 10.1016/j.ijid.2020.09.868] [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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Nakkeeran K, Saravanan K, Babu P, John R. Evaluation of bone regeneration in periapical osseous defects with and without platelet rich plasma, combined calcium sulfate and autologous bone graft – A comparative study. Journal of Stomatology, Oral and Maxillofacial Surgery 2019; 120:196-202. [DOI: 10.1016/j.jormas.2018.11.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 11/12/2018] [Accepted: 11/19/2018] [Indexed: 11/30/2022]
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Affiliation(s)
- P. D. Bidinger
- Institute for Rural Health Studies, Hyderabad, Andhra Pradesh, India
| | - B. Nag
- Institute for Rural Health Studies, Hyderabad, Andhra Pradesh, India
| | - P. Babu
- Institute for Rural Health Studies, Hyderabad, Andhra Pradesh, India
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Batra U, Jain P, Babu P, Sharma M. 26P Incidence of T790M mutations after progression on first Line EGFR TKIS in advanced NSCLC: Real time data from a tertiary cancer institute in North India. J Thorac Oncol 2018. [DOI: 10.1016/s1556-0864(18)30306-x] [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: 11/16/2022]
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Bakthavatchalam YD, Kumar DT, Tayubi IA, Shankar BA, Babu P, Munusamy E, Thukkaram B, Ravi R, Doss CGP, Veeraraghavan B. In vitro efficacy and in silico analysis of cefixime-ofloxacin combination for Salmonella Typhi from bloodstream infection. J Appl Microbiol 2018. [PMID: 28650129 DOI: 10.1111/jam.13522] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIMS Recently, the cefixime-ofloxacin combination is approved by Drug Controller General of India to treat typhoid fever. We sought to evaluate the antimicrobial activity of cefixime-ofloxacin combination against Salmonella Typhi. METHODS AND RESULTS A total of 283 nonduplicate S. Typhi isolates collected during 2012-2014 were included in this study. Minimum inhibitory concentration (MIC) of cefixime and ofloxacin was determined by using broth microdilution method. Combinational testing was performed by using checkerboard assay. In checkerboard assay, synergistic activity was seen in 11% of isolates, while the majority of the isolate showed indifference and none of them showed antagonism. An in silico strategy, an alternative to the animal model, was carried out to understand drug interaction and toxicity. Molecular docking results elucidated that cefixime and ofloxacin are capable of inhibiting the cell wall synthesis and DNA replication, respectively. Computational ADMET analysis showed no toxicity and no drug-drug interaction between cefixime and ofloxacin. CONCLUSION Cefixime-ofloxacin combination could be effective against moderately susceptible fluoroquinolone S. Typhi but not fluoroquinolone-resistant isolates. SIGNIFICANCE AND IMPACT OF THE STUDY Cefixime-ofloxacin combination with no drug-drug interaction and nontoxic predicted through computational analysis did not show antagonism against S. Typhi in in vitro. Although this study showed no adverse effects with the cefixime-ofloxacin combination, further studies on pharmacokinetic and pharmacodynamic (PK-PD) parameters of cefixime and ofloxacin combination are warranted.
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Affiliation(s)
- Y D Bakthavatchalam
- Department of Clinical Microbiology, Christian Medical College, Vellore, Tamil Nadu, India
| | - D T Kumar
- Department of Integrative Biology, School of Biosciences and Technology, VIT University, Vellore, Tamil Nadu, India
| | - I A Tayubi
- Faculty of Computing and Information Technology, King Abdulaziz University, Rabigh, Saudi Arabia
| | - B A Shankar
- Department of Clinical Microbiology, Christian Medical College, Vellore, Tamil Nadu, India
| | - P Babu
- Department of Clinical Microbiology, Christian Medical College, Vellore, Tamil Nadu, India
| | - E Munusamy
- Department of Clinical Microbiology, Christian Medical College, Vellore, Tamil Nadu, India
| | - B Thukkaram
- Department of Clinical Microbiology, Christian Medical College, Vellore, Tamil Nadu, India
| | - R Ravi
- Department of Clinical Microbiology, Christian Medical College, Vellore, Tamil Nadu, India
| | - C G P Doss
- Department of Integrative Biology, School of Biosciences and Technology, VIT University, Vellore, Tamil Nadu, India
| | - B Veeraraghavan
- Department of Clinical Microbiology, Christian Medical College, Vellore, Tamil Nadu, India
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Varghese BK, Babu P, Roy T. Microsurgical free muscle flaps for reconstruction of post-traumatic complex tissue defects of foot. Med J Armed Forces India 2016; 72:131-9. [PMID: 27257323 DOI: 10.1016/j.mjafi.2016.02.004] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 02/18/2016] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Crush injuries of the foot often result in complex tissue loss with exposed bones and tendons. These three-dimensional defects ideally require flexible well-perfused flaps to fill the space, afford resistance to infections, and to provide supple, durable weight- and pressure-bearing surfaces. Free muscle flaps with split thickness skin graft cover have been found to have several advantages in covering three-dimensional defects with exposed tendons and bones. METHODS All patients with post-traumatic composite tissue defects of the foot exposing bones and tendons, who presented to a tertiary care center during a 40-month period, were reconstructed with free muscle flaps as the first option. Gracilis muscle flap was used for eight patients and latissimus dorsi muscle for two patients. Decision regarding the choice of muscle was based on the size of the defect. The patients were followed up for 1 year and observed for return to activity, ability to wear footwear, requirement of secondary procedures, and any other complications. RESULTS Ten patients presented with composite post-traumatic tissue defects in the foot. All were male, with age ranging from 25 to 76 years. The defects ranged from 25 cm(2) to 225 cm(2). Free muscle transfer was successful in nine patients. Even though four required secondary flap contouring, all patients had normal weight-bearing ambulation and returned to their normal activities at 1-year follow-up. CONCLUSION Free muscle flaps merit consideration as primary reconstructive option for post-traumatic composite tissue defects of foot.
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Affiliation(s)
- B K Varghese
- Associate Professor, Dept of Surgery, Armed Forces Medical College, Pune 411040, India
| | - P Babu
- Senior Advisor (Surgery & Reconstructive Surgery), Command Hospital (Air Force), Bengaluru, India
| | - T Roy
- DMS (E&S), Air HQ, RK Puram (Med Directorate), New Delhi, India
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Shankar C, Anandan S, Babu P, Munusamy E, Veeraraghavan B. Correlation of carbapenem resistance and hypermucoviscosity in K.pneumoniae isolated from blood culture at a tertiary hospital in South India. Int J Infect Dis 2016. [DOI: 10.1016/j.ijid.2016.02.291] [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: 10/22/2022] Open
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Babu P, Rajamani V. Evolutionary Algorithm Based Optimized Histogram Modification for Contrast Enhancement of Mammogram Images. j med imaging hlth inform 2016. [DOI: 10.1166/jmihi.2016.1693] [Citation(s) in RCA: 3] [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: 11/23/2022]
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Pulipati S, Koushik O, Babu P. Phytochemical Analysis and Antibacterial Efficacy of Mentha piperita (L) Ethanolic Leaf Extract against Clinical Isolates of Uropathogens. ACTA ACUST UNITED AC 2016. [DOI: 10.9734/bmrj/2016/24031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Babu P, Martín I, Venkata Krishnaiah K, Seo HJ, Venkatramu V, Jayasankar C, Lavín V. Photon avalanche upconversion in Ho3+–Yb3+ co-doped transparent oxyfluoride glass–ceramics. Chem Phys Lett 2014. [DOI: 10.1016/j.cplett.2014.03.048] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Mohan V, Jayaraman T, Babu P, Dorny P, Vercruysse J, Rajshekhar V. Prevalence and risk factors for Taenia solium taeniasis in Kaniyambadi block, Tamil Nadu, South India. Indian J Public Health 2014; 58:202-3. [DOI: 10.4103/0019-557x.138638] [Citation(s) in RCA: 5] [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: 11/04/2022] Open
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Neelakandan K, Babu P, Nair S. Emerging roles for modulation of microRNA signatures in cancer chemoprevention. Curr Cancer Drug Targets 2012; 12:716-40. [PMID: 22515522 DOI: 10.2174/156800912801784875] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Revised: 02/16/2012] [Accepted: 03/23/2012] [Indexed: 11/22/2022]
Abstract
miRNAs are small endogenous non-coding RNAs, approximately 21-nucleotides in length, which are shown to regulate an array of cellular processes such as differentiation, cell cycle, cell proliferation, apoptosis, and angiogenesis which are important in cancer. miRNAs can function as both tumor promoters (oncomiRs) or tumor suppressors by their ability to target numerous biomolecules that are important in carcinogenesis. Aberrant expression of miRNAs is correlated with the development and progression of tumors, and the reversal of their expression has been shown to modulate the cancer phenotype suggesting the potential of miRNAs as targets for anti-cancer drugs. Several chemopreventive phytochemicals like epigallocatechin-3-gallate, curcumin, isoflavones, indole-3-carbinol, resveratrol, and isothiocyanate have been shown to modulate the expression of numerous miRNAs in cancer cells that lead to either abrogation of tumor growth or sensitization of cancer cells to chemotherapeutic agents. This review focuses on the putative role(s) of miRNAs in different aspects of tumorigenesis and at various stages of early drug discovery that makes them a promising class of drug targets for chemopreventive intervention in cancer. We summarize the current progress in the development of strategies for miRNA-based anti-cancer therapies. We also explore the modulation of miRNAs by various cancer chemopreventive agents and the role of miRNAs in drug metabolism. We will discuss the role of miRNAs in cancer stem cells and epithelial-to-mesenchymal transition; and talk about how modulation of miRNA expression relates to altered glycosylation patterns in cancer cells. In addition, we consider the role of altered miRNA expression in carcinogenesis induced by various agents including genotoxic and epigenetic carcinogens. Finally, we will end with a discussion on the potential involvement of miRNAs in the development of cancer chemoresistance. Taken together, a better understanding of the complex role(s) of miRNAs in cancer may help in designing better strategies for biomarker discovery or drug targeting of miRNAs and/or their putative protein targets.
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Affiliation(s)
- K Neelakandan
- Cancer Discovery Biology Laboratory, Division of Molecular Medicine, Amrita Centre for Nanosciences and Molecular Medicine; Amrita Institute of Medical Sciences and Research Centre, Amrita School of Pharmacy, Amrita Vishwa Vidyapeetham University, Kerala, India
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Venkatramu V, Luis SFL, Lozano-Gorrín AD, Jyothi L, Babu P, Rodríguez-Mendoza UR, Jayasankar CK, Muñoz-Santiuste JE, Lavín V. Structural and luminescence properties of Ho(3+)/Yb(3+)-doped Lu3Ga5O12 nano-garnets for phosphor applications. J Nanosci Nanotechnol 2012; 12:4495-4501. [PMID: 22905491 DOI: 10.1166/jnn.2012.6179] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [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
Lu3Ga5O12 nano-garnet powders doped with Ho(3+)/Yb(3+) ions have been prepared using a citrate sol-gel technique. The structural and morphological properties have been investigated by X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy. The materials are found to exist in single phase of cubic garnet structure with an average particle size of around 45 nm. The Ho(3+)/Yb(3+)-doped Lu3Ga5O12 nano-garnet powders give rise to an intense green and weak red emission of Ho3+ ions under 457.5 nm direct excitation. Moreover, when the Yb3+ ions are excited at 950 nm a very bright green luminescence of the Ho3+ ions is observed by the naked eyes even for such low laser power as 10 mW and the intensity of the red emission have been increased compared to that found under direct excitation of the Ho3+ ions. The power dependency and dynamics of the infrared-to-visible upconverted luminescence confirm the existence of different two-photon energy transfer processes. All these results have been compared with those obtained for other garnets doped with similar lanthanide ions which suggest that the Lu3Ga5O12 nano-garnets are potential materials for light emitting devices.
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Affiliation(s)
- V Venkatramu
- Department of Physics, Yogi Vemana University, Kadapa 516 003, India
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Babu P, Jang KH, Rao CS, Shi L, Jayasankar CK, Lavín V, Seo HJ. White light generation in Dy(3+)-doped oxyfluoride glass and transparent glass-ceramics containing CaF2 nanocrystals. Opt Express 2011; 19:1836-1841. [PMID: 21368998 DOI: 10.1364/oe.19.001836] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The radiative emission properties of the Dy3+ ions in an oxyfluoride glass and glass-ceramics have been studied for the generation of white light. The x-ray diffraction pattern of the glass-ceramics shows the formation of CaF2 fluorite-type nanocrystals in the glass matrix after a suitable thermal treatment of the precursor glass, whereas time-resolved optical measurements show the incorporation of the Dy3+ ions in the CaF2 nanocrystals. Intense white light has been observed when the samples are excited with 451 nm laser light. From the visible emission spectra, yellow to blue intensity ratios and the chromaticity color coordinates have been determined. All the color coordinates are found to lie in the white light region of the chromaticity color diagram.
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Affiliation(s)
- P Babu
- Department of Physics, Pukyong National University, Busan 608-737, South Korea
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Venkatramu V, Babu P, Martín IR, Lavín V, Muñoz-Santiuste JE, Tröster T, Sievers W, Wortmann G, Jayasankar CK. Role of the local structure and the energy trap centers in the quenching of luminescence of the Tb3+ ions in fluoroborate glasses: A high pressure study. J Chem Phys 2010; 132:114505. [DOI: 10.1063/1.3352631] [Citation(s) in RCA: 9] [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: 11/14/2022] Open
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Babu J, Kumar S, Babu P, Prasad JH, Ghoshal UC. Frequency of lactose malabsorption among healthy southern and northern Indian populations by genetic analysis and lactose hydrogen breath and tolerance tests. Am J Clin Nutr 2010; 91:140-6. [PMID: 19889824 DOI: 10.3945/ajcn.2009.27946] [Citation(s) in RCA: 54] [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: 11/14/2022] Open
Abstract
BACKGROUND Lactose malabsorption (LM), the inability to break down lactose into glucose and galactose, is due to a deficiency in the small intestinal lactase phlorizin hydrolase enzyme. Ethnic and geographic variations of LM are known. OBJECTIVE The aim of this study was to compare the frequency of LM in healthy southern and northern Indian populations. DESIGN A total of 153 healthy volunteers (76 from southern and 77 from northern India) were evaluated for LM by using a lactose tolerance test (LTT), a lactose hydrogen breath test (lactose HBT), and polymerase chain reaction-restriction fragment length polymorphism to identify the lactase gene C/T-13910 polymorphism (confirmed by sequencing). RESULTS Volunteers from southern and northern India were comparable in age and sex. The LTT result was abnormal in 88.2% of southern Indians and in 66.2% of northern Indians (P = 0.001). The lactose HBT result was abnormal in 78.9% of southern Indians and in 57.1% of northern Indians (P = 0.003). The CC genotype was present in 86.8% and 67.5% (P = 0.002), the CT genotype was present in 13.2% and 26.0% (P = 0.036), and the TT genotype was present in 0% and 6.5% (P = 0.03) of southern and northern Indians, respectively. The frequency of symptoms after the lactose load (47.4% compared with 15.6%; P < 0.001) and peak concentrations of breath hydrogen (88.5 +/- 71.9 compared with 55.4 +/- 61.9 ppm; P = 0.003), both of which might indicate the degree of lactase deficiency, were higher in southern than in northern Indians. CONCLUSION The frequency and degree of LM is higher in southern than in northern Indian healthy populations because of genetic differences in these populations.
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Affiliation(s)
- Janaki Babu
- Department of Gastroenterology, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, India
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Praveena R, Venkatramu V, Babu P, Jayasankar CK, Tröster T, Sievers W, Wortmann G. Luminescence properties of Sm(3+)-doped P(2)O(5)-PbO-Nb(2)O(5) glass under high pressure. J Phys Condens Matter 2009; 21:035108. [PMID: 21817267 DOI: 10.1088/0953-8984/21/3/035108] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [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
Samarium doped lead phosphate glass modified with niobium having a composition (in mol%) of 55P(2)O(5)+39.5PbO+5Nb(2)O(5)+0.5Sm(2)O(3) has been prepared by the conventional melt quenching technique. The emission spectra and the decay curves for the (4)G(5/2) level of Sm(3+) ions have been measured as a function of pressure up to 23.6 GPa at room temperature. A discontinuity in the observed shifts and crystal-field splittings as a function of pressure around 9-10 GPa suggests that a phase transition is taking place in the glass matrix. The [Formula: see text], (6)H(7/2) and (6)H(9/2) transitions are shifted towards the lower energy side with magnitudes of -7.1, -7.6 and -5.5 cm(-1) GPa(-1) up to 8.9 GPa (phase 1) and -5.6, -4.9 and -4.4 cm(-1) GPa(-1) beyond 10.3 GPa (phase 2), respectively. A much stronger increase in the splitting of the [Formula: see text] and [Formula: see text] Stark levels with pressure is observed in phase 1 than in phase 2. The lifetime of the (4)G(5/2) level decreases from 2.29 ms (0 GPa) to 0.64 ms (23.6 GPa) with pressure. The decay curves of the (4)G(5/2) level exhibit non-exponential behavior for all the pressures and were fitted by the generalized Yokota-Tanimoto model to probe the nature of the energy transfer process. The best fits with S = 6 indicate that the energy transfer between donor and acceptor is of dipole-dipole type. The crystal-field splitting experienced by the Sm(3+) ions in the title glass are found to be larger than those found in borate, K-Ba-Al phosphate and tellurite glasses.
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Affiliation(s)
- R Praveena
- Department of Physics, Sri Venkateswara University, Tirupati-517 502, India
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Babu P, Seo HJ, Jang KH, Upendra Kumar K, Jayasankar C. 1.55μm emission and upconversion properties of Er3+-doped oxyflurotellurite glasses. Chem Phys Lett 2007. [DOI: 10.1016/j.cplett.2007.07.073] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [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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Kumar KU, Prathyusha VA, Babu P, Jayasankar CK, Joshi AS, Speghini A, Bettinelli M. Fluorescence properties of Nd3+-doped tellurite glasses. Spectrochim Acta A Mol Biomol Spectrosc 2007; 67:702-8. [PMID: 17027327 DOI: 10.1016/j.saa.2006.08.027] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2006] [Revised: 08/17/2006] [Accepted: 08/20/2006] [Indexed: 05/12/2023]
Abstract
The compositional and concentration dependence of luminescence of the (4)F(3/2)-->(4)I(J) (J=13/2, 11/2 and 9/2) transitions in four Nd(3+)-doped tellurite based glasses has been studied. The free-ion energy levels obtained for 60TeO(2)+39ZnO(2)+1.0Nd(2)O(3) (TZN10) glass have been analysed using the free-ion Hamiltonian model and compared with similar results obtained for Nd(3+):glass systems. The absorption spectrum of TZN10 glass has been analysed using the Judd-Ofelt theory. Relatively longer decay rates have been obtained for Nd(3+)-doped phosphotellurite glasses. The emission characteristics of the (4)F(3/2)-->(4)I(11/2) transition, of the Nd(3+):TZN10 glass, are found to be comparable to those obtained for Nd(3+):phosphate laser glasses. The non-exponential shape of the emission decay curves for the (4)F(3/2)-->(4)I(11/2) transition is attributed to the presence of energy transfer processes between the Nd(3+) ions.
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Affiliation(s)
- K Upendra Kumar
- Department of Physics, Sri Venkateswara University, Tirupati 517 502, India
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Surendra Babu S, Babu P, Jayasankar CK, Joshi AS, Speghini A, Bettinelli M. Luminescence and optical absorption properties of Nd(3+) ions in K-Mg-Al phosphate and fluorophosphate glasses. J Phys Condens Matter 2006; 18:3975-3991. [PMID: 21690752 DOI: 10.1088/0953-8984/18/16/007] [Citation(s) in RCA: 5] [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: 05/30/2023]
Abstract
Absorption and emission properties and fluorescence lifetimes for the [Formula: see text] transition of Nd(3+) ions embedded in P(2)O(5)-K(2)O-MgO-Al(2)O(3) (PKMA)-based glasses modified with AlF(3) and BaF(2) are reported at room temperature. The observed energy levels of Nd(3+) ions in these glasses have been analysed through a semi-empirical free-ion Hamiltonian model. The spin-orbit interaction and net electrostatic interaction experienced by the Nd(3+) ions follow the trend as PKMA>PKMA+AlF(3)> PKMA+BaF(2) glasses. Judd-Ofelt analysis has been carried out on the absorption spectra of 1.0 mol% Nd(3+)-doped glasses to predict the radiative properties for the fluorescent levels of the Nd(3+) ion. Branching ratios and stimulated emission cross-sections show that the [Formula: see text] transition of the glasses under investigation has the potential for laser applications. The Inokuti-Hirayama model has been applied to investigate the non-radiative relaxation of the Nd(3+) ion emitting state, (4)F(3/2). Based on the decay curve analysis, concentration quenching of the (4)F(3/2) emission has been attributed to a cross-relaxation process between the Nd(3+) ions.
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Affiliation(s)
- S Surendra Babu
- Department of Physics, Sri Venkateswara University, Tirupati-517 502, India
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Surendra Babu S, Babu P, Jayasankar CK, Tröster T, Sievers W, Wortmann G. Photoluminescence from the (5)D(0) level of Eu(3+) ions in a phosphate glass under pressure. J Phys Condens Matter 2006; 18:1927-1938. [PMID: 21697566 DOI: 10.1088/0953-8984/18/6/009] [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
The pressure dependence of the luminescence from [Formula: see text] transitions of Eu(3+) ions in 58.5P(2)O(5)-9Al(2)O(3)-14.5BaO-17K(2)O-1Eu(2)O(3) glass has been investigated up to 38.3 GPa at room temperature. The relative luminescence intensity ratio of [Formula: see text] to [Formula: see text] transitions of the Eu(3+) ions is found to decrease with increasing pressure, indicating a lowering of the asymmetry around the Eu(3+) ions with pressure. The [Formula: see text] transitions exhibit pressure-induced red shifts of different magnitude, which suggests a decrease in Slater parameters (F(k)) and in the spin-orbit coupling parameters (ζ) for the Eu(3+) ions. Stark components of the (7)F(1) level have been used to evaluate the crystal-field (CF) parameters B(20) and B(22), which are in turn used to estimate the CF strength experienced by the Eu(3+) ions in the glass. The observed increase in the CF strength parameter is found to have an almost cubic dependence on pressure. Luminescence decay curves for the [Formula: see text] transition are found to be single exponential over the entire pressure range studied. The lifetime did not change under pressure up to 5 GPa, although a significant change in the CF strength is noticed in this pressure range. The reduction of lifetime observed at pressures above 5 GPa could be partially due to an increase of pressure-induced defect centres. Such a process can then explain the hysteresis observed in the variation of lifetime and crystal-field strength on the release of pressure.
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Affiliation(s)
- S Surendra Babu
- Department of Physics, Sri Venkateswara University, Tirupati-517 502, India
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Venkatramu V, Babu P, Jayasankar CK. Fluorescence properties of Eu3+ ions doped borate and fluoroborate glasses containing lithium, zinc and lead. Spectrochim Acta A Mol Biomol Spectrosc 2006; 63:276-81. [PMID: 15979397 DOI: 10.1016/j.saa.2005.05.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2005] [Accepted: 05/10/2005] [Indexed: 05/03/2023]
Abstract
The influence of glass composition on the fluorescence properties of Eu3+ ions doped borate and fluoroborate glasses modified with Li+, Zn2+ and Pb2+ cations have been investigated. The magnitude of splittings of 7F1 levels are analyzed using crystal-field (CF) analysis. The relative intensities of 5D0 --> 7F2 to 5D0 --> 7F1 transitions, crystal-field strength parameters and decay times of the 5D0 level have been determined and are found to be lower for Pb based glasses than those of Zn/Li based glasses. The lifetimes of 5D0 level are found to increase when borate glasses are modified with pure fluorides than with oxides and oxyfluorides. The fluorescence decay of 5D0 level fits perfect single exponential in the Eu3+:glass systems studied which indicates the absence of energy transfer between Eu3+ ions in these glasses.
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Affiliation(s)
- V Venkatramu
- Department of Physics, Sri Venkateswara University, Tirupati 517502, India
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Abstract
A new class of alkyl-chain-appended pyrene derivatives 4-14 were synthesized and evaluated for their gelation abilities. Depending on the nature of the linking group, these compounds gelated a number of organic solvents, either in the presence or in the absence of the acceptor molecule 2,4,7-trinitrofluorenone (TNF). Compounds with ester, ether, or alkyl linkages gelated a number of hydroxylic and hydrocarbon solvents by means of a charge-transfer interaction with TNF, while compounds with amide, urethane and urea linkers formed gels on their own in a variety of solvents by means of pi-pi stacking and hydrogen-bonding interactions. The Xray crystal structure of urethane (S)-12 showed hydrogen-bonding and stacking features, as suggested by the model. The gels obtained were investigated by spectroscopic and electron microscopic techniques which provided structural insights.
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Affiliation(s)
- P Babu
- Department of Organic Chemistry, Indian Institute of Science, Bangalore 560 012, India
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Lavı́n V, Babu P, Jayasankar CK, Martı́n IR, Rodrı́guez VD. On the local structure of Eu3+ ions in oxyfluoride glasses. Comparison with fluoride and oxide glasses. J Chem Phys 2001. [DOI: 10.1063/1.1420731] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Bindu PC, Babu P. Surfactant-induced lipid peroxidation in a tropical euryhaline teleost Oreochromis mossambicus (Tilapia) adapted to fresh water. Indian J Exp Biol 2001; 39:1118-22. [PMID: 11906104] [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] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
Exposure to anionic (sodium dodecyl sulfate, SDS), cationic (cetyl trimethyl ammonium bromide CTAB) and non ionic (Triton X-100) surfactants at a sub lethal concentration of 1 ppm resulted in severe oxidative stress in the hepatic, renal and cardiac tissues of fresh water adapted Oreochromis mossambicus. Hepatic catalase showed significant increase (P<0.001) in all the surfactant exposed fish, but the renal enzyme was significantly increased only in CTAB dosed fish (P<0.001) and the cardiac enzyme showed significant increase in Triton (P<0.05) and CTAB dosed fish (P<0.001). SOD levels were significantly increased (P<0.001) in hepatic, renal and cardiac tissues of all the surfactant-treated fish. Glutathione reductase also was significantly increased (P<0.001) in the hepatic and renal tissues of surfactant dosed fish except cardiac tissues of CTAB exposed animals. Glutathione levels in the tissues studied were significantly higher in the surfactant treated animals (P<0.001) whereas malondialdehyde levels were significantly elevated only in the hepatic tissues of animals exposed to Triton (P<0.001). The surfactants based on their charge, antioxidant profile and in vivo metabolism may be arranged in the order of decreasing toxicity as CTAB > Triton > SDS. Thus it may be inferred from the present study that the antioxidant defenses and the in vivo metabolism of the surfactants are key factors in deciding the surfactant toxicity.
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Affiliation(s)
- P C Bindu
- Department of Marine Biology, Microbiology & Biochemistry, School of Marine Sciences, Cochin University of Science & Technology, Kochi
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Krishnamurthy B, Jagdish S, Pai D, Babu P. Transection of common bile duct following blunt injury to abdomen. Indian J Gastroenterol 1997; 16:109-10. [PMID: 9248186] [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] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Isolated complete transection of the common bile duct due to blunt abdominal trauma is rare. We report such a case following an assault.
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Affiliation(s)
- B Krishnamurthy
- Department of Surgery, Jawaharlal Institute of Postgraduate Medical Education and Researoh, Pondicherry
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Abstract
We have studied the influence of some mutations in the bithorax complex on the observed synapsis dependent phenotype of the genotypes Cbx1Ubx1/+ and bx3 4e/Ubx1. The effect of these mutations is similar to that introduced by disruption of pairing or by the za mutation. Among the bx mutations, we find that bx8 behaves differently from most other bx mutations in its influence on the synapsis dependent phenotype. This observation induced us to map the position of bx8 with respect to other bx mutations; we find that it maps between bx3 4e and bx3. We show how some of the observations reported here can be fitted into a model of activation of the bithorax complex proposed by one of us.
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Affiliation(s)
- P Babu
- Molecular Biology Unit, Tata Institute of Fundamental Research, Bombay, India
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Abstract
Mutants in the gene flu-2 of the free-living nematode Caenorhabditis elegans are characterised by an altered autofluorescence of the intestine cells, from the light blue of wild-type to a dull green colour. The properties of flu-2 mutants have been investigated. L-kynureninase activity has been detected in wild-type C. elegans. The flu-2 mutants have markedly reduced kynureninase activity, as predicted earlier from chromatographic analysis of tryptophan catabolites of wild-type and mutant worms. Associated with this enzymatic block, all flu-2 mutants have enhanced sensitivity to ethyl methane sulfonate (EMS) and gamma-rays.
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Abstract
Genetic mosaics can be generated by x-irradiation in the simple nematode Caenorhabditis elegans. A mutation in the gene flu-3 alters the characteristic autofluorescence of intestinal cells under ultraviolet light and can be used as a cell- and tissue-specific marker. Embryos heterozygous for flu-3 give rise to adults with patches of these altered intestinal cells. The previously established intestinal cell lineage in Caenorhabditis elegans and the distribution and sizes of the fluorescent patches are consistent with a somatic segregation of the flu-3 allele.
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Abstract
The relation of intestinal autofluorescence to tryptophan catabolism in the free-living nematode Caenorhabditis elegans has been investigated. L-Kynurenine hydroxylase (EC 1.14.13.9) activity has been detected in normal (wild-type) individuals. Mutants in the gene flu-1 which are characterized by an altered autofluorescence of the intestine cells, i.e., more intense than wild type and bluish purple instead of light blue have also been examined. They show a markedly reduced activity of kynurenine hydroxylase. The finding supports the previously proposed model for altered fluorescence based on chromatographic identification of tryptophan catabolites present.
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Abstract
The properties of the mutation wingless discovered by Sharma are discussed. It appears that this mutation interferes with a step leading to normal wing-notum compartmentation of the wing disk. From the study of mutational mosaics in the wingless locus we conclude that mutations in this gene can be autonomous in mosaics.
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