Some polishing experiments on copper in a hyperbolic cell

Some polishing experiments have been carried out on copper anodes in a hyperbolic cell designed by Gilmont and Walton, using orthophosphoric acid as the electrolyte. The results obtained have been compared to those obtained in similar experiments in a Hull cell. It has been found that very similar bands of different reflectivity and polishes are found to form in both the cells. These bands shift with time and a study of such displacements has been made. The results are briefly discussed.     

Analysis of a model for transport of charged particles in a random magnetic field

A model for the transport of charged particles in a random magnetic field is a Volterra integrodifferential equation with a long-range kernel. The integrodifferential equation is solved numerically with the method of Bellman, Kalaba, and Lockett (“Numerical Inversion of the Laplace Transform,” Elsevier, New York, 1966). The results are shown to be in excellent agreement with analytical asymptotic results.     

Influence of Sm<Superscript>3+</Superscript> ion in structural,morphological, and electrochemical properties of LiMn<Subscript>2</Subscript>O<Subscript>4</Subscript> synthesized by microwave calcination

LiSm_xMn_2–xO₄ samples were synthesized via co-precipitation technique. The structural properties of the synthesized materials were studied using X-ray diffraction analysis and it confirmed the cubic spinel structure for all the compounds. The lattice parameter of LiMn₂O₄ was observed to be 8.2347 Ǻ and it decreased with Sm³⁺ concentration, due to the shrinkage in cell volume aided by higher binding energy between Sm-O bond. The SEM micrographs were analyzed using Image processing software (Image-J) to ascertain the pore and grain properties. The microwave synthesis had been observed to control the bulk grain formation and had yielded lesser porous and nanoparticles. The particle size distributions obtained through photocross correlation laser diffraction analysis had shown that LiMn₂O₄ with 60 nm and Sm-doped compounds with ∼30 nm, respectively. The cyclic voltammetry studies had revealed the decrease in electrocatalytic behavior in the initial cycle for compounds doped with Sm³⁺ ion. The initial capacities of LiMn₂O₄, LiSm_0.05Mn_1.95O₄ and LiSm_0.10Mn_1.90O₄ substituted compounds were observed to be 134.87 mAhg⁻¹, 132.22 mAhg⁻¹ and 126.41 mAhg⁻¹, respectively. The cells were simulated using 1D model namely Dualfoil5.1 program. The simulated results coincide well with the measured results. The cycle life studies reveal 93% capacity retention of samarium-0.05-doped samples when compared with 78.4% of the LiMn₂O₄.     

Preparation of 4(3H)-quinazolinones from aryldiazonium salt,nitriles and 2-aminobenzoate via a cascade annulation

One-pot synthesis of 3-aryl-4(3H)-quinazolinones has been realized through a cascade annulation. Reaction of aryldiazonium salt with a nitrile provides in situ generation of a reactive nitrilium ion, which is attacked by the amino group of 2-aminobenzoate followed by cyclization to deliver the desired product. This strategy offers a convenient and easy access to a wide range of functionalized quinazolinone.     

Improved pulse schemes for separated local field spectroscopy for static and spinning samples

An improved pulse sequence for SLF experiments based on the magic sandwich (MS) scheme for homo-nuclear dipolar decoupling is proposed. The sequence incorporates a double MS, both on I and S spins and has been named as EXE-MS2. The proposed scheme which has a scaling factor of 1 is observed to be free from low intensity artifacts and provides better line-widths particularly for S spins labeled at multiple sites. The pulse sequence which has been applied on static oriented samples incorporates the EXE scheme where direct polarization of the S spin in the B(0) field is utilized in the place of polarization inversion and is observed to perform well without any loss of sensitivity while ensuring considerable reduction in rf power input into the sample. The EXE scheme has also been tested for solid samples under MAS.     

Experimental analysis of tamarind seed powder-based flash powder composition for eco-friendly firecrackers

Journal of Thermal Analysis and Calorimetry - In this work, considering the various practical concerns during storage, processing, handling and emission of flash powder used for making firecracker,...     

A self-assembled tetrapeptide that acts as a “turn-on” fluorescent sensor for Hg2+ ion

The tetrapeptide (Bz-$\mathrm{\Delta }$Phe(p-NPh₂)-l-DOPA(protected)-l-Phe-l-Phe-OMe was designed to incorporate seven phenyl rings so that it’s conformation, self-assembly and application in Hg²⁺ ions sensing could be studied. Peptide molecules adopted an overlapping β-turn of type III/III conformation in crystals. The peptide showed a highly selective turn-on response towards mercuric ion over other metal ions with a 10-fold enhancement in fluorescence intensity. This intensity change coupled with the selectivity of the peptide towards mercury allowed us to demonstrate simple colorimetric dip sensing of Hg²⁺ ions. The technique provides a highly selective and effective way to detect Hg²⁺ ions. The peptide also self-assembled into nanospheres with diameter ranges from 100 to 500?nm. Mercuric ion coordination enabled these peptide nanospheres to aggregate into well-defined nanoparticles. The enhanced fluorescence upon Hg²⁺ addition demonstrates that peptide scaffolds can be exploited in the development of different selective sensors.     

Crystal and molecular structure of 7-hydroxyflavone monohydrate, C14H10O3·H2O

The X-ray crystal structure of 7-hydroxyflavone monohydrate, C₁₄H₁₀O₃ · H₂O, is determined. The compound crystallizes in the monoclinic space group, P2₁/n with a = 3.801(3), b = 19.665(4), c = 16. 039(6), = 93.69(3)°, and = 0.68 mm^–1 for Z = 4. The phenyl ring of the flavone moiety is rotated 18.6(1)° out of the penzopyran plane, which is a typical value for flavones. In the crystal lattice, there are wide channels which are lined mainly by C–H groups. The water molecules enclosed in these channels are severely disordered.     

Synergy between Brønsted acid sites and Lewis acid sites

Synergy between Br?nsted acid sites and Lewis acid sites in mesoporous Al-Zr-TUD-1 was demonstrated to exist in Br?nsted acid catalysed reactions, but not in Lewis acid catalysed reactions.     

Control of porosity geometry in amino acid derived nanoporous materials

Substitution of the pillaring ligand in the homochiral open-framework [Ni(2)(L-asp)(2)(bipy)] by extended bipy-type ligands leads to a family of layer-structured, homochiral metal-organic frameworks. The 1D channel topology can be modified by the nature of the organic linker, with shape, cross-section and the chemical functionality tuneable. In addition, the volume of these channels can be increased by up to 36 % compared to the parent [Ni(2)(L-asp)(2)(bipy)]. The linker 1,4-dipyridylbenzene (3rbp) gives access to a new layered homochiral framework [Ni(2)(L-asp)(2)(3rbp)] with channels of a different shape. In specific cases, non-porous analogues with the linker also present as a guest can be activated to give porous materials after sublimation. Their CO(2) uptake shows an increase of up to 30 % with respect to the parent [Ni(2)(L-asp)(2)(bipy)] framework.