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41.
Di-bariummagnesium silicate phosphors doped with europiumand dysprosium were prepared under a weak reducing atmosphere. X-ray diffraction pattern of the sample was also done that confirmed the proper preparation of the phosphor. Scanning electron microscope (SEM) images confirmed that the sample has regular surface and uniform grain size distribution. Comparative studies of phosphorescence decay of Ba2MgSi2O7:Eu2+, Dy3+ phosphors with different concentration of Dy3+ were done. The phosphor with 0.5/1.5 mol% of Eu/Dy, exhibited optimum green color afterglow properties. This emission is expected to arise due to transition of Eu2+ ions from any of the sublevels of 4f65d1 configuration to 8S7/2 level of the 4f7 configuration. For a suitable trap depth, the trap concentration is expected to be proportional to the concentration of Dy3+. These traps are responsible for holding the charge career for a reasonable time, subsequently for increasing the time of afterglow. Hence, optimum Dy3+ concentration produces the longer afterglow duration with higher intensity of luminescence signals. Trap depth were also calculated using thermoluminescence glow curve which was indicative of formation of traps suitable for long afterglow. 相似文献
42.
Arjun K. Mishra Nidhi Singh Pragati Agnihotri Shikha Mishra Saurabh P. Singh Bala K. Kolli Kwang Poo Chang Amogh A. Sahasrabuddhe M. I. Siddiqi J. Venkatesh Pratap 《Journal of computer-aided molecular design》2017,31(6):547-562
Nucleoside diphosphate kinases (NDKs) are ubiquitous enzymes that catalyze the transfer of the γ-phosphate moiety from an NTP donor to an NDP acceptor, crucial for maintaining the cellular level of nucleoside triphosphates (NTPs). The inability of trypanosomatids to synthesize purines de novo and their dependence on the salvage pathway makes NDK an attractive target to develop drugs for the diseases they cause. Here we report the discovery of novel inhibitors for Leishmania NDK based on the structural and functional characterization of purified recombinant NDK from Leishmania amazonensis. Recombinant LaNDK possesses auto-phosphorylation, phosphotransferase and kinase activities with Histidine 117 playing an essential role. LaNDK crystals were grown by hanging drop vapour diffusion method in a solution containing 18% PEG-MME 500, 100 mM Bis-Tris propane pH 6.0 and 50 mM MgCl2. It belongs to the hexagonal space group P6322 with unit cell parameters a?=?b?=?115.18, c?=?62.18 Å and α?=?β?=?90°, γ?=?120°. The structure solved by molecular replacement methods was refined to crystallographic R-factor and Rfree values of 22.54 and 26.52%, respectively. Molecular docking and dynamics simulation-based virtual screening identified putative binding compounds. Protein inhibition studies of selected hits identified five inhibitors effective at micromolar concentrations. One of the compounds showed ~45% inhibition of Leishmania promastigotes proliferation. Analysis of inhibitor-NDK complexes reveals the mode of their binding, facilitating design of new compounds for optimization of activities as drugs against leishmaniasis. 相似文献
43.
44.
Lamotrigine (LTG) is an antiepileptic drug used for the prevention of convulsions. Except several known side effects, hepatic
dysfunction is also reported. Hepatotoxic side effects occur due to the dichlorophenyl moiety which develops an abnormally
low level of glutathione. Depletion of glutathione causes oxidative stress and hepatic cell damage. The goal of the present
study was to test the action and side effects of the three compounds synthesised and compared to LTG. Three amide prodrugs
of LTG were synthesised by its reaction with N-acetylamino acids, viz, glycine, glutamic acid, and methionine. Purified synthesised prodrugs were subjected to thin layer
chromatography, melting point, solubility and partition coefficients determination and characterised by UV, FTIR, 1H and 13C NMR spectroscopy. The synthesised prodrugs were subjected to in vitro hydrolysis and to anticonvulsant and hepatotoxic activity
studies. Significant reduction in hepatotoxicity and comparable anticonvulsant activities were obtained in all synthesised
prodrugs as compared to LTG. 相似文献
45.
Falconi M Oteri F Di Palma F Pandey S Battistoni A Desideri A 《Journal of computer-aided molecular design》2011,25(2):181-194
Comparative homology modelling techniques have been used to model the protein ZnuA from Salmonella enterica serovar Typhimurium using the 3D structure of the homologous protein from Escherichia coli. These two-domain proteins bind one Zn2+ atom, with high affinity, in the inter-domain cleft and possess a histidine-rich loop in the N-terminal domain. Alternative
structures of the ZnuA histidine-rich loop, never resolved by the X-ray diffraction method, have been modelled. A model of
the apo form, one with the histidine-rich loop deleted and two alternative structures with a second zinc ion bound to the
histidine-rich loop, have been generated. In all the modelled proteins, investigated through molecular dynamics simulation,
the histidine-rich loop is highly mobile and its fluctuations are correlated to the ligand stability observed in the zinc
sites. Based on the plasticity of the histidine-rich loop and its significant effects on protein mobility a possible role
in the capture and/or transfer of the zinc ions has been suggested. 相似文献
46.
Singh SK Tibrewal NK Rajaraman G 《Dalton transactions (Cambridge, England : 2003)》2011,40(41):10897-10906
Theoretical calculations using density functional methods have been performed on two dinuclear {Ni(II)-Gd(III)} and two trinuclear {Ni(II)-Gd(III)-Ni(II)} complexes having two and three μ-OR (R = alkyl or aromatic groups) bridging groups. The different magnetic behaviour, having moderately strong ferromagnetic coupling for complexes having two μ-OR groups and weak ferromagnetic coupling for complexes having three μ-OR groups, observed experimentally is very well reproduced by the calculations. Additionally, computation of overlap integrals MO and NBO analysis reveals a clear increase in antiferromagnetic contribution to the net exchange for three μ-OR bridged {Ni-Gd} dimers and also provides several important clues regarding the mechanism of magnetic coupling. Besides, MO and NBO analysis discloses the role of the empty 5d orbitals of the Gd(III) ion on the mechanism of magnetic coupling. Magneto-structural correlations for Ni-O-Gd bond angles, Ni-O and Gd-O bond distances, and the Ni-O-Gd-O dihedral angle have been developed and compared with the published experimental {Ni-Gd} structures and their J values indicate that the Ni-O-Gd bond angles play a prominent role in these types of complexes. The computation has then been extended to two trinuclear {Ni(II)-Gd(III)-Ni(II)} complexes and here both the {Ni-Gd} and the {Ni-Ni} interactions have been computed. Our calculations reveal that, for both structures studied, the two {NiGd} interactions are ferromagnetic and are similar in strength. The {Ni-Ni} interaction is antiferromagnetic in nature and our study reveals that its inclusion in fitting the magnetic data is necessary to obtain a reliable set of spin Hamiltonian parameters. Extensive magneto-structural correlations have been developed for the trinuclear complexes and the observed J trend for the trinuclear complex is similar to that of the dinuclear {Ni-Gd} complex. In addition to the structural parameters discussed above, for trinuclear complexes the twist angle between the two Ni-O-Gd planes is also an important parameter which influences the J values. 相似文献
47.
A validated spectrophotometric method has been developed for the determination of uranyl ion in soil samples. The method is based on the complexation reaction between uranyl ion and rifampicin in methanol‐water medium at room temperature. The method is followed spectrophotometrically by measuring the absorbance at 375 nm. Under the optimized experimental conditions, Beer's law is obeyed in the concentration range of 1.35–20.25 μg mL‐1 with apparent molar absorptivity and Sandell's sensitivity of 8.0 × 103 L mol‐1cm‐1 and 0.042 μg/cm2/0.001 absorbance unit, respectively. The interference of a large number of anions and cations has been investigated and the optimized conditions developed have been utilized for the determination of uranium(VI) in soil samples. The three sigma detection limit (n = 9) for uranyl ion was found to be 0.20 μg mL‐1. The proposed method was successfully applied to the determination of uranyl ion in soil samples. 相似文献
48.
The Ramanujan Journal - Let $$\lambda _f (n)$$ denote the normalized n-th Fourier coefficient of a holomorphic Hecke eigencuspform or a Hecke–Maass cusp form for the full modular group. In... 相似文献
49.
50.
Alok Kumar Rastogi A. K. Tiwari R. P. Shrivastava 《International Journal of Infrared and Millimeter Waves》1993,14(7):1445-1453
The dielectric optical wave guide is finding growing attention at millimeter wave frequencies. However the dielectric optical waveguide radiates at bends and thus transmission loss increases. These radiations are in the outword direction of bends. This output radiation at output bends arises due to change in phase velocities of the propagating wave at the centre of the dielectric guide and the phase velocity at the outer surface of the dielectric guide. A unique methiod is suggested to avoid these radiation losses.Experimental results are also shown at microwave frequencies. 相似文献