9 results on '"Jayasankar, J."'
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2. Efficiency of CuCr 2 O 4 /Titanium dioxide nanoparticles composite for organic dye removal in aqueous solutions.
- Author
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Sivaranjani SK, Durairaj K, Jayalakshmi G, Sumathi J, Balasubramanian B, Chelliapan S, Kamyab H, Hashim H, and Kavitha D
- Subjects
- Titanium chemistry, Spectroscopy, Fourier Transform Infrared, Light, Water, Coloring Agents chemistry, Catalysis, Nanocomposites chemistry, Nanoparticles
- Abstract
Semiconductor metal oxide with TiO
2 nanoparticles removes hazardous compounds from environmental samples. TiO2 nanoparticles have shown potential as an efficient photocatalyst by being employed as a nano-catalyst for the breakdown of organic contaminants in wastewater samples. To separate substances from contaminated samples, combined UV and visible light irradiation has been used. Sol-gel synthesis was used to produce a copper chromite-titanium nanocomposite, which was then evaluated using analytical methods, such as XRD, BET, DRS-UV, and FT-IR. Using visible light, the photocatalytic activity of a nanocomposite made of CuCr2 O4 and TiO2 was investigated for its role in the breakdown of malachite green. The effects of several parameters, including pH change, anions presence, contact time, catalyst amount, concentration variation, and the kinetics of photocatalytic degradation were investigated. The magnitude of transition energy calculated using UV-DRS spectra was found to be 3.1 eV for CuCr2 O4 - TiO2 nanocomposite. Maximum degradation was observed at pH 7.0. The surface area and pore volume of the co-doped samples of Cr2 O4 - TiO2 obtained from BET were found to be 6.1213 m2 /g and 0.045063 cm3 /g respectively. The average particle size of the catalyst of the nano-catalysts calculated from XRD was found to be 8 nm for TiO2 and 66 nm for TiO2 -CuCrO4 . The peaks obtained in FTIR between the range of 900-500 cm-1 were due to the presence of an aromatic compound. The binding mechanism of a dye molecule to the surface of CuCr2 O4 -TiO2 nanocomposite was analysed using quantum chemical calculations with the self-consistent reaction field technique employing integral equation formalism for the polarized continuum method and the UFF atomic radii set., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)- Published
- 2023
- Full Text
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3. The protective role of sulforaphane and Homer1a in retinal ischemia-reperfusion injury: Unraveling the neuroprotective interplay.
- Author
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Saadh MJ, Castillo-Acobo RY, Baher H, Narayanan J, Palacios Garay JP, Yamaguchi MNV, Arias-Gonzáles JL, Cotrina-Aliaga JC, Akram SV, Lakshmaiya N, Amin AH, Mohany M, Al-Rejaie SS, Ahsan M, Bahrami A, and Akhavan-Sigari R
- Subjects
- Mice, Animals, Nestin pharmacology, Mice, Inbred C57BL, Apoptosis, Evoked Potentials, Visual, Reperfusion Injury drug therapy, Reperfusion Injury prevention & control, Reperfusion Injury metabolism
- Abstract
Aims: Retinal ischemia/reperfusion (I/R) injury is a common pathological basis for various ophthalmic diseases. This study aimed to investigate the potential of sulforaphane (SFN) and Homer1a in regulating cell apoptosis induced by retinal I/R injury and to explore the underlying regulatory mechanism between them., Materials and Methods: In in vivo experiments, C57BL/6J mice and Homer1
flox/- /Homer1a+/- /Nestin-Cre+/- mice were used to construct retinal I/R injury models. In vitro experiments utilized the oxygen-glucose deprivation-reperfusion (OGD/R) injury model with primary retinal ganglion cells (RGCs). The effects of Homer1a and SFN on cell apoptosis were observed through pathological analyses, flow cytometry, and visual electrophysiological assessments., Key Findings: We discovered that after OGD/R injury, apoptosis of RGCs and intracellular Ca2+ activity significantly increased. However, these changes were reversed upon the addition of SFN, and similar observations were reproduced in in vivo studies. Furthermore, both in vivo and in vitro studies confirmed the upregulation of Homer1a after I/R, which could be further enhanced by the administration of SFN. Moreover, upregulation of Homer1a resulted in a reduction in cell apoptosis and pro-apoptotic proteins, while downregulation of Homer1a had the opposite effect. Flash visual evoked potential, oscillatory potentials, and escape latency measurements in mice supported these findings. Furthermore, the addition of SFN strengthened the neuroprotective effects in the OGD/R + H+ group but weakened them in Homer1flox/- /Homer1a+/- /Nestin-Cre+/- mice., Significance: These results indicate that Homer1a plays a significant role in the therapeutic potential of sulforaphane for retinal I/R injury, thereby providing a theoretical basis for clinical treatment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Inc.)- Published
- 2023
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4. Spectroscopic assessment of Dy 3+ ions in lead fluorosilicate glass as a prospective material for solid state yellow laser.
- Author
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Manasa P and C K J
- Abstract
Lead fluorosilicate (SKNPfLfDy) glasses doped with various Dy
3+ ion concentrations employed via melt-quenching method have been prepared and studied their thermal, optical and spectral properties for the spreading out of yellow laser applications. The emission spectra have prominent emission at 575 nm (4 F9/2 →6 H13/2 ) transition. The stimulated emission cross-section (5.14 × 10-21 cm2 ) and branching ratio (62%) for the4 F9/2 →6 H13/2 transition were found to be relatively high. Lifetime is decreased from 1192 μs to 34 μs with increase in concentration due to concentration quenching as well cross-relaxation among the Dy3+ ions. The quantum efficiency found to be 69%. The optical gain, figure of merit, yellow/blue (Y/B) intensity ratio and gain bandwidth for 1.0 mol% Dy3+ :SKNPfLf glass is found to be 27.55 × 10-25 cm2 s, 19.01 × 10-25 cm2 s, 3.96 and 63.32 × 10-28 cm3 , respectively. The obtained results revealed that the SKNPfLfDy glasses possibly useful for yellow laser applications., (Copyright © 2019. Published by Elsevier B.V.)- Published
- 2019
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5. Optical spectroscopy, 1.06μm emission properties of Nd 3+ -doped phosphate based glasses.
- Author
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Sk Nayab R, T S, A MB, L RM, and C K J
- Abstract
Neodymium doped phosphate based glasses with composition of (P
2 O5 +K2 O+Al2 O3 +CaF2 ) were prepared. The samples were analysed through differential thermal analysis (DTA), Fourier transform infrared (FTIR), absorption, emission and decay measurements. Judd-Ofelt parameters (Ωλ ) have been determined from the spectral intensities of absorption bands in order to calculate the radiative parameters like radiative transition probabilities (AR ), radiative lifetime (τR ) and branching ratios (βR ) for the4 F3/2 →4 I11/2 laser transition of Nd3+ ion. The effective emission bandwidths (Δλeff ), experimental branching ratios (βexp ) and stimulated emission cross-sections (σe ) have been determined from the emission spectrum. The decay curves of the4 F3/2 level exhibited almost single exponential nature for all the Nd3+ ion concentrations., (Copyright © 2017 Elsevier B.V. All rights reserved.)- Published
- 2017
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6. Structural and luminescent properties of KY(1-x)DyxBO3 phosphors.
- Author
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G S, L RM, Ch B, and C K J
- Abstract
Yttrium borate phosphors (KY(1-x)DyxBO3) doped with Dy(3+) ions were synthesized by the solid-state reaction method. The structural and morphological characteristics were studied by XRD, FTIR and SEM measurements. Luminescent properties of different concentrations of KY(1-x)DyxBO3 phosphors were investigated from the excitation, emission and decay analyses. The emission spectra exhibited characteristic blue (460-500nm) and yellow (555-610nm) bands of Dy(3+) ions which combines to give white light. The evaluated color co-ordinates (x, y) were found to lie within the white light region of CIE chromaticity diagram. All the decay curves of Dy(3+) ions exhibited non-exponential nature and the experimental lifetimes for the (4)F9/2 excited level were found to decrease from 0.87, 0.47, 0.35, 0.26 and 0.13ms with the increase of Dy(3+) ion concentrations from 0.05, 0.1, 0.15, 0.2 and 0.3mol%, respectively. In order to understand the energy transfer mechanism, the decay curves were fitted to Inokutti-Hirayama model and found that the energy transfer is of dipole-dipole type. From the results of these investigations, it is concluded that the KY(1-x)DyxBO3 phosphors are more useful for white light emitting diodes., (Copyright © 2016 Elsevier B.V. All rights reserved.)
- Published
- 2017
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7. Crystal structure of echicetin from Echis carinatus (Indian saw-scaled viper) at 2.4A resolution.
- Author
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Jasti J, Paramasivam M, Srinivasan A, and Singh TP
- Subjects
- Base Sequence, Binding Sites, Carrier Proteins, Conserved Sequence, Crystallography, X-Ray, Dimerization, Models, Molecular, Molecular Sequence Data, Protein Conformation, Protein Subunits chemistry, Proteins isolation & purification, Proteins chemistry, Viper Venoms chemistry
- Abstract
Echicetin is a heterodimeric protein from the venom of the Indian saw-scaled viper, Echis carinatus. It binds to platelet glycoprotein Ib (GPIb) and thus inhibits platelet aggregation. It has two subunits, alpha and beta, consisting of 131 and 123 amino acid residues, respectively. The two chains are linked with a disulphide bond. The level of amino acid sequence homology between two subunits is 50%. The protein was purified from the venom of E.carinatus and crystallized using ammonium sulphate as a precipitant. The crystal structure has been determined at 2.4A resolution and refined to an R-factor of 0.187. Overall dimensions of the heterodimer are approximately 80Ax35Ax35A. The backbone folds of the two subunits are similar. The central portions of the polypeptide chains of alpha and beta-subunits move into each other to form a tight dimeric association. The remaining portions of the chains of both subunits fold in a manner similar to those observed in the carbohydrate-binding domains of C-type lectins. In echicetin, the Ca(2+)-binding sites are not present, despite being topologically equivalent to other similar Ca(2+)-binding proteins of the superfamily. The residues Ser41, Glu43 and Glu47 in the calcium-binding proteins of the related family are conserved but the residues Glu126/120 are replaced by lysine at the corresponding sites in the alpha and beta-subunits.
- Published
- 2004
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8. Crystal structure of a proteolytically generated functional monoferric C-lobe of bovine lactoferrin at 1.9A resolution.
- Author
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Sharma S, Jasti J, Kumar J, Mohanty AK, and Singh TP
- Subjects
- Animals, Binding Sites, Cattle, Crystallography, X-Ray, Cysteine chemistry, Cystine chemistry, Electrons, Hydrogen chemistry, Hydrogen Bonding, Hydrogen-Ion Concentration, Ions, Iron, Models, Molecular, Protein Conformation, Protein Folding, Protein Structure, Tertiary, Lactoferrin chemistry
- Abstract
This is the first crystal structure of a proteolytically generated functional C-lobe of lactoferrin. The purified samples of iron-saturated C-lobe were crystallized in 0.1 M Mes buffer (pH 6.5) containing 25% (v/v) polyethyleneglycol monomethyl ether 550 M and 0.1 M zinc sulphate heptahydrate. The X-ray intensity data were collected with 300 mm imaging plate scanner mounted on a rotating anode generator. The structure was determined by the molecular replacement method using the coordinates of the C-terminal half of bovine lactoferrin as a search model and refined to an R-factor of 0.193 for all data to 1.9A resolution. The final model comprises 2593 protein atoms (residues 342-676 and 681-685), 124 carbohydrate atoms (from ten monosaccharide units, in three glycan chains), one Fe(3+), one CO(3)(2-), two Zn(2+) and 230 water molecules. The overall folding of the C-lobe is essentially the same as that of C-terminal half of bovine lactoferrin but differs slightly in conformations of some of the loops and reveals a number of new interactions. There are 20 Cys residues in the C-lobe forming ten disulphide links. Out of these, one involving Cys481-Cys675 provides an inter-domain link at 2.01A while another Cys405-Cys684 is formed between the main C-lobe 342-676 and the hydrolyzed pentapeptide 681-685 fragment. Six inter-domain hydrogen bonds have been observed in the structure whereas only four were reported in the structure of intact lactoferrin, although domain orientations have been found similar in the two structures. The good quality of electron density has also revealed all the ten oligosaccharide units in the structure. The observation of two metal ions at sites other than the iron-binding cleft is another novel feature of the present structure. These zinc ions stabilize the crystal packing. This structure is also notable for extensive inter-molecular hydrogen bonding in the crystals. Therefore, the present structure appears to be one of the best packed crystal structures among the proteins of the transferrin superfamily.
- Published
- 2003
- Full Text
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9. First structural evidence of a specific inhibition of phospholipase A2 by alpha-tocopherol (vitamin E) and its implications in inflammation: crystal structure of the complex formed between phospholipase A2 and alpha-tocopherol at 1.8 A resolution.
- Author
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Chandra V, Jasti J, Kaur P, Betzel Ch, Srinivasan A, and Singh TP
- Subjects
- Animals, Colubridae, Crystallography, X-Ray, Dimerization, Dose-Response Relationship, Drug, Electrons, Hydrogen Bonding, Kinetics, Light, Models, Molecular, Phospholipases A2, Protein Binding, Scattering, Radiation, Inflammation metabolism, Phospholipases A antagonists & inhibitors, Phospholipases A chemistry, alpha-Tocopherol chemistry, alpha-Tocopherol pharmacology
- Abstract
This is the first structural evidence of alpha-tocopherol (alpha-TP) as a possible candidate against inflammation, as it inhibits phospholipase A2 specifically and effectively. The crystal structure of the complex formed between Vipera russelli phospholipase A2 and alpha-tocopherol has been determined and refined to a resolution of 1.8 A. The structure contains two molecules, A and B, of phospholipase A2 in the asymmetric unit, together with one alpha-tocopherol molecule, which is bound specifically to one of them. The phospholipase A2 molecules interact extensively with each other in the crystalline state. The two molecules were found in a stable association in the solution state as well, thus indicating their inherent tendency to remain together as a structural unit, leading to significant functional implications. In the crystal structure, the most important difference between the conformations of two molecules as a result of their association pertains to the orientation of Trp31. It may be noted that Trp31 is located at the mouth of the hydrophobic channel that forms the binding domain of the enzyme. The values of torsion angles (phi, psi, chi(1) and chi(2)) for both the backbone as well as for the side-chain of Trp31 in molecules A and B are -94 degrees, -30 degrees, -66 degrees, 116 degrees and -128 degrees, 170 degrees, -63 degrees, -81 degrees, respectively. The conformation of Trp31 in molecule A is suitable for binding, while that in B hinders the passage of the ligand to the binding site. Consequently, alpha-tocopherol is able to bind to molecule A only, while the binding site of molecule B contains three water molecules. In the complex, the aromatic moiety of alpha-tocopherol is placed in the large space at the active site of the enzyme, while the long hydrophobic channel in the enzyme is filled by hydrocarbon chain of alpha-tocopherol. The critical interactions between the enzyme and alpha-tocopherol are generated between the hydroxyl group of the six-membered ring of alpha-tocopherol and His48 N(delta1) and Asp49 O(delta1) as characteristic hydrogen bonds. The remaining part of alpha-tocopherol interacts extensively with the residues of the hydrophobic channel of the enzyme, giving rise to a number of hydrophobic interactions, resulting in the formation of a stable complex.
- Published
- 2002
- Full Text
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