Browsing by Author "Jayasree, R. S."

Now showing 1 - 6 of 6
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    Effect of 980-nm Diode Laser and 1064-nm Nd:YAG Laser on the Intervertebral Disc-In Vitro and in Vivo Studies
    (PHOTOMEDICINE AND LASER SURGERY, 2009)
    Objective: Our aim was to histologically evaluate the thermal changes in bovine intervertebral discs caused by 980-nm diode and 1064-nm Nd:YAG lasers. Further aims were to standardize the technique for in vivo animal research and to study its efficacy for clinical practice. Background: When conservative methods fail, surgery has so far been the only measure for severe back pain due to disc prolapse and herniation. Recently, the minimally invasive technique of laser disc decompression has become more popular because it has advantages over open surgery in properly selected cases. Methods: In vitro studies were done with Nd: YAG and diode lasers ( 1064 and 980 nm, respectively) on bovine intervertebral discs using a bare fiber tip or a focusing lens attached to a fiber tip. These studies were followed by in vivo studies in a canine model using a Nd: YAG laser with a bare fiber tip. Autopsies were done immediately and at 3, 6, 9, and 12mo after ablation and the histopathology of excised discs was evaluated. Results: Depending upon the depth of ablation and the intensity of charring and carbonization, a standardized energy density and pulse duration were identified. Conclusion: Nd: YAG laser with initial delivery of 40-W laser power and a reduced power of 10-15W thereafter, delivering a total energy density of 1500 2000J/cm(2) using a bare fiber tip, is recommended for clinical applications.
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    Enhanced luminescence observed in polyaniline-polymethylmethacrylate composites
    (JOURNAL OF ALLOYS AND COMPOUNDS, 2008)
    Polyaniline (PANI) is one of the highly pursued conducting polymers owing to its high electrical conductivity, interesting optical properties and excellent environmental stability. Recently, it is also being used extensively as hole-injecting electrodes in polymer LEDs. Inspite of its excellent electrical properties, the mechanical strength and processibility are not very attractive. It is reported that making composites of PANI with conventional polymers such as polymethylmethacrylate (PMMA), significantly improves the mechanical strength and processibility. Recently, we have observed that the DC electrical conductivity of HCl doped PANI can be further enhanced by making composites with PMMA. PMMA has been reported to have excellent optical properties such as very good transparency in the visible region and fairly good photoluminescence emission. This prompted us to carry out investigations on the optical properties of this composite, especially the photoluminescence characteristics. In the present work, we have synthesized PANI-PMMA composites using bulk polymerized PMMA. The FTIR spectrum reveals that PANI has been dispersed as an interpenetrating network in the PMMA matrix. The change in the photoluminescence (PL) behaviour of PANI-PMMA composites with different aniline to PMMA feed ratios has been investigated. It is observed that the photoluminescence intensity increases with increase in the PMMA content in the composite, possibly due to greater chances of exciton formation and subsequent radiative decay to the ground state. The PL spectrum of PMMA is also taken for comparison. The enhancement in the PL intensity of the composites with increase in the aniline to PMMA feed ratio is quite comparable with the enhancement in the DC electrical conductivity of these composites. (c) 2006 Elsevier B.V. All rights reserved.
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    Percutaneous laser disc decompression: Clinical experience at SCTIMST and long term follow up
    (NEUROLOGY INDIA, 2006)
    Background: Low backache (LBA) is now increasing in younger population due to misdirected spinal kinetics secondary to improper posture, heavy load lifting and motorbike driving. Hence minimally invasive procedures are increasingly sought after. Among these, PLDD is currently popular and in use. We present our long term follow-up in the use of Nd:YAG laser for PLDD. Aim: To herniation of lumbar discs & long term follow up results. Materials and Methods: Forty patients with contained lumbar disc herniation on MRI and who did not respond to 6 weeks conservative treatment were subjected to PLDD. L4-5 disc was treated in 31, L5-S1 in 12 and L1-2 and L3-4 in one each. Nd:YAG laser at 1064 nm was used for the procedure. Total laser energy of 1500-2000 Joules was delivered at the disc space depending upon the size. Results: There was immediate pain relief in 32/40 (80%). According to MacNab criteria good to fair response was seen in 37/40 (92%) and 3 patients (7.5%) responded poorly to this treatment. On follow up which ranged from 1 to 7 years, 34/40 (85%) had pain relief with no need for further treatment. Complications: Significant pain at local puncture site was experienced by 8 (20%), pain during lasing was experienced by one. One patient developed muscular spasm. Conclusion: Percutaneous laser disc decompression is a safe, relatively noninvasive and effective treatment modality for contained, nonsequestered, herniated lumbar disc disease in carefully selected patients.
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    Polyaniline doped with orthophosphoric acid - A material with prospects for optoelectronic applications
    (JOURNAL OF ALLOYS AND COMPOUNDS, 2008)
    Polyaniline (PANI) is one of the highly pursued conducting polymers in recent times owing to its excellent electrical and optical properties, better air stability and easy and cheap synthesis route. Doped PANI has been extensively investigated as a hole-injecting electrode in polymer light en-fitting diodes (LEDs). However, the work on doped PANI as emissive layers in polymer LEDs is quite scanty. Though there are reports on the photoluminescence characteristics of doped PANI, a detailed investigation on a comparative study of the photo luminescence in PANI doped with different dopants, which is the essence of our work, has not been carried out earlier. In the present work, we compare the photoluminescence (PL) emission intensity of PANI doped with hydrochloric acid (HCl), camphor sulphonic acid (CSA) and orthophosphoric acid, with a view to assessing the prospects of doped PANI as emissive layer in polymer LEDs. The PL emission peak is centered around 450 nm when excited at 365 nm. PANI doped with orthophosphoric acid exhibits the highest photoluminescent intensity followed by PANI doped with HCl and CSA. A comparison of the X.R.D spectra of the samples show that both HCl doped PANI and CSA doped PANI, do not show any significant crystalline nature whereas orthophosphoric acid doped PANI exhibits considerable crystallanity. The observed long-range order in orthophosphoric acid doped PANI could be a consequence of the more orderly arrangement of benzenoid and quinonoid units, resulting in enhanced PL emission intensity. (C) 2007 Elsevier B.V. All rights reserved.
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    Spectroscopic and thermal analysis of a submandibular sialolith of Wharton's duct resected using Nd : YAG laser
    (LASERS IN MEDICAL SCIENCE, 2008)
    A sialolith observed in the Wharton's duct of a male patient was resected using an Nd:YAG laser. This is the first report on the resection of sialolith using laser. The resected sample was analyzed for structural details using Fourier transform infrared (FTIR), FT-Raman, and fluorescence spectroscopic techniques. Other techniques like energy dispersive X-ray analysis, scanning electron microscopy, and thermal analysis were also used for the analysis of structural details. The major peaks of the vibrational spectra are observed to be due to the vibrations of the phosphate and hydroxyl groups of the inorganic part of the sample and the proteinaceous component of the organic part. The major elements in the sample are identified as calcium and phosphorous in the ratio 7:3. The fluorescence spectra recorded at excitation wavelengths 280, 325, and 410 nm showed emission maxima corresponding to the endogenous fluorescence of structural proteins and amino acids. The inorganic part of the sialolith remained stable even at temperatures up to 1,673 K. The spectroscopic studies indicated that the structure of the sialolith is similar to that of the dentine part of the human teeth. In situ disintegration of the sialolith involves very high temperature. High calcium and phosphorous content in the food may be attributed to one of the reasons for the formation of sialoliths.
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    Vibrational spectra of mono, di and trimethyl ammonium double sulphates of rare earths Pr, Nd, Ho and Eu
    (SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY, 2006)
    Infrared and Raman spectra of four rare earth (Ho, Eu, Nd and Pr) double sulphates have been recorded and analysed based on the vibrations of methyl ammonium cations, sulphate anions and water molecules. Formation of hydrogen bonds of the type N-H center dot center dot center dot O and O-H center dot center dot center dot O are identified in all the compounds. Bifurcated hydrogen bonds are present in the compounds with dimethyl ammonium cations. The sulphate anions are distorted and occupy a lower site symmetry in the compounds. The bands obtained for (CH3)(2)NH2 and SO42- ions indicate that the structural bonding of (CH3)(2)NH2Eu(SO4)(2)center dot H2O and (CH3)(2)NH2Ho(SO4)(2)center dot 4H(2)O is identical. Electronic transition bands of Eu3+ and Nd3+ observed in the Raman spectra of these two compounds have been identified and discussed. (c) 2005 Elsevier B.V. All rights reserved.