Study of the peak effect phenomenon in single crystals of 2H-NbSe2

The weakly pinned single crystals of the hexagonal 2H-NbSe₂ compound have emerged as prototypes for determining and characterizing the phase boundaries of the possible order-disorder transformations in the vortex matter. We present here a status report based on the ac and dc magnetization measurements of the peak effect phenomenon in three crystals of 2H-NbSe₂, in which the critical current densities vary over two orders of magnitude. We sketch the generic vortex phase diagram of a weakly pinned superconductor, which also utilizes theoretical proposals. We also establish the connection between the metastability effects and pinning.     

Amberlite IR-120 catalysed efficient synthesis of glycosyl enamines and their application

β-Keto esters and acetyl acetone on condensation with glycosylated amino esters in the presence of IR-120 resin resulted in high yields of glycosyl enamino esters or ketones. The latter on cyclisation with NaH in toluene at reflux gave 6-glycosyl-5,6-dihydro-1H-pyridin-4-ones in fair to good yields.     

Facile Synthesis of Pyrazolo[3,4‐d]pyrimidines and Pyrimido[4,5‐d]pyrimidin‐4‐one Derivatives

Pyrazolopyrimidine and pyrimidopyrimidine derivatives have shown a wide range of biological activities such as acting as A₁ adenosine receptors, kinase insert domain receptor (KDR), Rous sarcoma oncogene (Src), epidermal growth factor receptor (EGFR), antiproliferative, dihydrofolate reductase (DHFR), antimicrobial, antifungal, and lipid peroxidation. Because of this wide range of activities, we have synthesized pyrazolo[3,4‐d]pyrimidines and pyrimido[4,5‐d]pyrimidin‐4‐one derivatives.     

Non-isothermal degradation kinetics of PLA-functionalized gum (fG) biocomposite with dicumyl peroxide (DCP)

Journal of Thermal Analysis and Calorimetry - In the present investigation, gene expression programming (GEP) is used to predict thermal conductivity of nanofluids consisting of $$\hbox {Al}_2\hbox...     

Densitometric HPTLC Analysis of Juglone,Quercetin, Myricetin,Rutin, Caffeic Acid,and Gallic Acid in Juglans regia L.

JPC – Journal of Planar Chromatography – Modern TLC - Asensitive, selective, and precise high-performance thin-layer chromatography (HPTLC) method was developed for simultaneous...     

Synthesis,Spectral Studies and Bio‐activity of Some Ligand Bridged Polymeric Transition Metal Complexes of Acetone p‐Amino Acetophenone Isonicotinoyl Hydrazone

Ligand bridged polymeric complexes of the type [M(apainh)(H₂O)X] where, M=Mn(II), Co(II), Ni(II), Cu(II), and Zn(II); X=Cl₂ or SO₄; apainh=acetone p‐amino acetophenone isonicotinoyl hydrazone have been synthesized and characterized. The complexes are stable solids, insoluble in common organic solvents and are non‐electrolytes. Magnetic moments and electronic spectral studies suggest a spin‐free octahedral geometry for all Mn(II), Co(II), Ni(II), and Cu(II) complexes. IR spectra show tridentate nature of the ligand bonding through two >C?N and a >C?O groups. X‐ray powder diffraction parameters for some of the complexes correspond to orthorhombic and tetragonal crystal lattices. Thermal studies (TGA and DTA) of [Mn(apainh)(H₂O)SO₄] complex show multi‐step decomposition pattern of both an endothermic and exothermic nature. ESR data of Cu(II) chloride complex in solid state show an axial spectra, whereas, Cu(II) sulfate complex is isotropic in nature. The complexes show a significant antifungal activity against a number of pathogenic fungal species and antibacterial activity against Pseudomonas sp. and Clostridium sp. The metal complexes are more active than the ligand.     

Emergence of the sub‐THz central peak at phase transitions in artificial BaTiO3/(Ba,Sr)TiO3 superlattices

A prominent central peak in the sub‐THz frequency range was observed in the Raman spectra of BaTiO₃/(Ba,Sr)TiO₃ (BT/BST) superlattice grown on (001)MgO substrate. Both soft and central mode show an anomaly around 200 K and 280 K, which can be correlated with orthorhombic to monoclinic phase transition of BST and BT, respectively. The observed temperature dependence of the central mode enabled us to explain rather broad temperature dependence of the dielectric permittivity previously observed in BT/BST superlattices. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Resolution,absolute configuration and antifilarial activity of coumarinyl amino alcohols

The resolution of racemic coumarinyl amino alcohols 5–10 was achieved by using the inexpensive and readily accessible chiral resolving agent N-carbethoxy-l-proline (S)-11. Direct esterification of rac-5–10 with (S)-11 furnished diastereomeric esters, which were easily separated by column chromatography. The obtained diastereomers yielded the desired enantiopure coumarinyl amino alcohols (S)-(+)-5–10 and (R)-(?)-5–10 in good yields with high enantiomeric excess on saponification. The absolute configurations were determined by X-ray crystal analysis and/or by comparison of the specific rotations. Furthermore, in in vitro antifilarial motility inhibition assays, enantiopure coumarins (S)-(+)-9, (R)-(?)-9 and (S)-(+)-10, (R)-(?)-10 were found to be less efficient in affecting the viability of macrofilariae of Brugia malayi than their racemic forms 9 and 10, respectively, indicating the synergistic effect of the enantiomers in evoking antifilarial action.     

Investigations of sol–gel-derived highly (100)-oriented Ba0.5Sr0.5TiO3 : MgO composite thin films for phase-shifter applications

Sol–gel deposition of highly oriented Ba_0.5Sr_0.5TiO₃:MgO composite thin films has shown desirable dielectric constant reduction and higher figure of merit for phase-shifter applications. In this multilayer configuration, MgO distributed homogeneously through the Ba_0.5Sr_0.5TiO₃ (BST50) matrix, and it helped in tailoring the dielectric constant and reducing the loss tangent significantly. In the present study, the high-frequency dielectric behavior of the films has been evaluated by fabricating an eight-element coupled microstrip phase shifter and measuring the degree of phase shift and insertion loss as a function of applied voltage at room temperature. An increase in phase-shifter figure of merit (degree of phase shift per dB insertion loss) from 28°/dB for pure BST50 to 71°/dB for a BST50:MgO film (at 14 GHz and 333 kV/cm) has been observed. PACS 77.55.+f; 81.20.Fw; 73.40.-c; 85.50.-n