Computing Eigen value equation and modal dispersion characteristics of an elliptical Bragg waveguide

Using the method of separation of variables in the elliptical coordinate system, a recursive formula for the electromagnetic fields in a new type of Bragg waveguide having elliptical core cross section with multilayered cladding is derived. The eigen equation is written in the form of Mathieu and the modified Mathieu functions and a dispersion relation is obtained for various modes supported by the proposed Bragg waveguide. The cutoff frequencies for several lower order even-odd modes have been calculated and their propagation characteristics are plotted. The results show that the dispersion curves are discontinuous and modes can exist only in particular wavelength bands. The effects of elliptical eccentricity on the mode cutoff values and mode transmission are addressed. Finally, the modal birefringence in the said waveguide is also estimated.     

50 MeV Li3+ ion irradiation effect on structural, electrical, and dielectric properties of PVA-based nanocomposite polymer electrolytes

Nanocomposite polymer electrolyte thin films of polyvinyl alcohol (PVA)-orthophosphoric acid (H₃PO₄)-Al₂O₃ have been prepared by solution cast technique. Films are irradiated with 50 MeV Li³⁺ ions having four different fluences viz. 5?×?10¹⁰, 1?×?10¹¹, 5?×?10¹¹, and 1?×?10¹² ions/cm². The effect of irradiation on polymeric samples has been studied and characterized. X-ray diffraction spectra reveal that percent degree of crystallinity of samples decrease with ion fluences. Glass transition and melting temperatures have been also decreased as observed in differential scanning calorimetry. A possible complexation/interaction has been shown by Fourier transform infrared spectroscopy. Temperature-dependent ionic conductivity shows an Arrhenius behavior before and after glass transition temperature. It is observed that ionic conductivity increases with ion fluences and after a critical fluence, it starts to decrease. Maximum ionic conductivity of ～2.3?×?10^?5 S/cm owing to minimum activation energy of ～0.012 eV has been observed for irradiated electrolyte sample at fluence of 5?×?10¹¹ ions/cm². The dielectric constant and dielectric loss also increase with ion fluences while they decrease with frequency. Transference number of ions shows that the samples are of purely ionic in nature before and after ion irradiation.     

Design,Synthesis, and Biological and In Silico Study of Fluorine‐Containing Quinoline Hybrid Thiosemicarbazide Analogues

A novel series of fluorine‐containing quinoline hybrid thiosemicarbazide analogues ( 8a–8l ) were synthesized and tested for their biological activities. The antibacterial results demonstrated that compounds 8d and 8l [minimal inhibitory concentration (MIC) 62.5 μg/mL] were shown to have higher biological activity than ampicillin against Escherichia coli. Compound 8b (MIC 25 μg/mL) was shown to have the highest activity than was ampicillin against Staphylococcus aureus. The antifungal results demonstrated that compound 8j (MIC 100 μg/mL) has shown good activity. Most of the targeted compounds have shown potent antimalarial activity. Compounds 8d (0.19 μg/mL), 8g (0.30 μg/mL), 8h (0.36 μg/mL), 8k (0.10 μg/mL), 8l (0.28 μg/mL), 8k (0.10 μg/mL), and 8l (0.28 μg/mL) have notable activity than does the reference drug quinine. Compounds 8d (0.27 μg/mL), 8g (0.30 μg/mL), and 8k (0.17 μg/mL) have shown excellent activity against chloroquine‐resistant strain. The MTT assay performed on peripheral blood lymphocyte cultures showed a high percentage of lymphocyte viability [ 8d (99.64), 8g (99.46), 8h (98.83), and 8k (99.51)] at a maximum dose (10 μg/mL), depicting no cytotoxicity of these compounds on human lymphocytes in vitro. A molecular docking study was performed on Pf‐DHFR‐TS inhibitor. A molecular dynamics study has shown compound 8g to have better affinity with protein. ADME‐Tox and pharmacophore study of synthesized compounds suggested prediction of active site.     

Modal analysis of a super-elliptical Bragg waveguide with a small number of periodic cladding layers based on a very simple analytical technology

Using a simple matrix method and replacing the boundary condition by a matrix equation, the characteristic equation of an unconventional Bragg waveguide, namely a super-elliptical Bragg waveguide, has been obtained analytically. Computed results are shown in the form of dispersion curves and are compared with the dispersion curves of a standard step index fiber and a standard Bragg fiber having circular core [V. Singh, B. Prasad, S.P. Ojha. Analysis of the modal characteristics of a Bragg fiber with a small number of claddings using a very simple analytical approach, Microw. Opt. Technol. Lett. 46 (2005) 271-275 [1]]. It is seen that the correspondence between the cutoff values for the standard step index fiber and the new super-elliptical Bragg fiber is quite close for the lowest mode under the weak guidance condition.     

Growth,structure and optical characterization of Al‐doped ZnO nanoparticle thin films

Al‐doped ZnO nanoparticle thin films were prepared on glass substrate at the optimum temperature of (410±10) °C by spray pyrolysis technique using zinc nitrate as a precursor solution and aluminium chloride as a dopant. The dopant concentration (Al/Zn at%) was varied from 0 to 2 at%. Structural analysis of the films shows that all the films are of polycrystalline zinc oxide in nature, possessing hexagonal wurtzite structure. The films exhibit variation in peak intensities corresponding to (100), (002) and (101) reflection planes on Al‐doping. The crystallite size calculated by Scherrer formula has been found to be in the range of 35‐65 nm. The optical absorption study shows that the optical band gap in the Al‐doped films varies in the range of 3.11 – 3.22 eV. The width of localized states in the band gap estimated by the Urbach tail analysis has been found to be minimum in case of the 1 at% Al‐doped zinc oxide thin film. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis, characterization and chelating properties of poly [azo-(6-hydroxy-1,3-phenylene)]

Poly [azo(6-hydroxy-1,3-phenylene)] (PAHP) was prepared by alcoholic alkaline reduction of 2,4-dinitro phenol (DNP). The polymers prepared at various time intervals were characterized by elemental analyses, IR spectra and thermogravimetric analysis. The number average molecular weight was determined by non-aqueous titration. Viscometric study in DMF of all the three polymers were carried out and indicates polyelectrolyte behaviour. Viscometric study in DMF-water (85:15)(v/v) containing 1%KBr shows normal behaviour. Polymeric metal chelates of Cu²⁺, Ni²⁺, Co²⁺, Zn²⁺, Mn²⁺ and Cr²⁺ with PAHP polymer were prepared and characterized.     

Synthesis and characterization of coordination polymers of a carboxylato cyclophane with metal [Zn(II) and Cd(II)]-2,2′-bipyridines

N,N′,N′′,N′′′-Tetrakis(3-carboxy-propionyl)-1,6,20,25-tetraaza-[6.1.6.1] paracyclophane, H₄cp has been complexed with metal (Zn(II) and Cd(II)) 2,2′-bipyridyls. The resulting complexes of the composition [{Zn(2,2′-bpy)}₂(cp)]_n·4H₂O 1 and [{Cd(2,2′-bpy)}₂(cp)]_n·5H₂O 2 (2,2′-bpy = 2,2′-bipyridine) have been characterized using spectroscopic (IR, solid state UV–Vis), elemental analysis and single-crystal X-ray diffraction measurements. In these complexes the cyclophane coordinates in different modes, and in complex 2, Cd(II) is hepta-coordinated. However, under harsh reaction conditions (using excess nitric acid and a longer reaction time) debranching of the cyclophane is observed in the reaction of Zn(2,2′-bpy)(NO₃)₂ with H₄cp, and a complex of the composition [Zn(2,2′-bpy)(Suc)]_n3 (suc = succinate) is isolated. Using non-covalent interactions, complexes 1 and 2 provide 3D supramolecular structures, whereas an infinite 1D chain structure is observed for complex 3. The thermal and photoluminescence properties of the complexes have also been studied.     

Repurposing the antibacterial drugs for inhibition of SARS-CoV2-PLpro using molecular docking,MD simulation and binding energy calculation

Molecular Diversity - Papain-like protease (nsp-3; non-structural protein) of novel corona virus is an ideal target for developing drugs as it plays multiple important functions for viral growth...     

Zinc triflate: a highly efficient reusable catalyst in the synthesis of functionalized quinolines via Friedlander annulation

An environmentally friendly and highly efficient procedure for the preparation of quinolines and fused polycyclic quinolines has been developed by a simple Friedlander annulation reaction of 2-aminoaryl ketone with carbonyl compounds in presence of zinc triflate under microwave irradiation and solvent-free conditions. The reaction also proceeds effectively when In(OTf)₃ was used in lieu of Zn(OTf)₂ as the catalyst. The catalyst can be recovered after the reaction and reused efficiently in subsequent runs.     

Structural characterization and cytotoxicity studies of ruthenium(II)–dmso–chloro complexes of chalcone and flavone derivatives

A synthetic precursor cis-[Ru^IICl₂(dmso)₄] is complexed separately with 3-(4-benzyloxyphenyl)-1-(2-hydroxylphenyl)-prop-2-en-1-one (L¹H) and 2-(4-benzyloxyphenyl)-3hydroxy-chromen-4-one (L²H). The resulting complexes are assigned the composition fac-[RuCl(S-dmso)₃(L¹)] 1 and fac-[RuCl(S-dmso)₃(L²)] 2 using elemental analyses, FAB mass data and spectroscopic (IR, ¹H NMR, UV–Vis, emission) spectral properties. The X-ray diffraction analysis shows that complexes self-associate through non-covalent interactions and provide 1D and 2D supramolecular structures. These complexes are assayed for their cytotoxicity studies on Dalton Lymphoma cell lines.