Spectroscopic and docking studies of the binding of two stereoisomeric antioxidant catechins to serum albumins

The interactions of two stereoisomeric antioxidant flavonoids, catechin (C) and epicatechin (EC) with bovine serum albumin (BSA) and human serum albumin (HSA), have been investigated by steady state and time resolved fluorescence, phosphorescence, circular dichroism (CD), FTIR and protein–ligand docking studies. The steady-state fluorescence studies indicate a single binding site for both the ligands. FTIR spectra suggest that in both the albumins, C and EC stabilize the α-helix at the cost of a corresponding loss in the β-sheet structure. CD studies have been carried out using (±)C, and both the epimers (+)C and (?)C. The low temperature phosphorescence and protein–ligand [(+), (?) and (±) forms of C and EC] docking studies indicate that the ligands bind in the proximity of Trp 134 of BSA and Trp 214 of HSA, thereby changing their solvent accessible surface areas (ASA). Asn 158 and Glu 130 side chains are found to be within the hydrogen bonding distance from the phenolic –OH groups of C and EC in the case of BSA complex. C and EC are located within the binding pocket of sub-domain IIa of HSA.     

Synthesis and surface modified hard magnetic properties in Co0.5Pt0.5 nanocrystallites from a rheological liquid precursor

Small crystallites of a metastable phase Co_0.5Pt_0.5 are precipitated by heating a rheological liquid precursor of cobalt–hydrazine complex and platinum chloride H₂PtCl₆·xH₂O in polymer molecules of poly(vinylpyrrolidone) (PVP) in ethylene glycol. The hydrazine co-reduces nascent atoms from the Co²⁺ and Pt⁴⁺ that recombine and grow as Co_0.5Pt_0.5. The PVP molecules cap a growing Co_0.5Pt_0.5 as it achieves a critical size so that it stops growing further in given conditions. X-ray diffraction pattern of a recovered powder reveals a crystalline Co_0.5Pt_0.5 phase (average crystallite size D∼8 nm) of a well-known Fm3m-fcc crystal structure with the lattice parameter a=0.3916 nm (density ρ=14.09 g/cm³). A more ordered L1₀ phase (ρ=15.91 g/cm³) transforms (D≥25 nm) upon annealing the powder at temperature lesser than 700 °C (in vacuum). At room temperature, the virgin crystallites bear only a small saturation magnetization M_s=5.54 emu/g (D=8 nm) of a soft magnet and it hardly grows on bigger sizes (D≤31 nm) in a canted ferromagnetic structure. A rectangular hysteresis loop is markedly expanded on an optimally annealed L1₀ phase at 800 °C for 60 min, showing a surface modified coercivity H_c=7.781 kOe with remnant ratio M_r/M_s=0.5564, and M_s=39.75 emu/g. Crystallites self-assembled in an acicular shape tailor large H_c from ideal single domains and high magnetocrystalline anisotropy of a hard magnet L1₀ phase.     

Evidence of a core–shell structure in the antiferromagnetic La0.2Ce0.8CrO3 nanoparticles by neutron scattering

We report the evidence of a core?Cshell structure in the antiferromagnetic La_0.2Ce_0.8CrO₃ nanoparticles by using a combination of neutron diffraction, polarized neutron small angle scattering (SANSPOL), and dc magnetization techniques. The neutron diffraction study establishes that the present nanoparticles are antiferromagnetic in nature. The magnetic scattering in the SANSPOL study arises from the shell part of the nanoparticles due to the disordered surface spins. The analysis of the SANSPOL data shows that these nanoparticles have a mean core diameter of 12.3±1.1?nm, and a shell thickness of 2.8±0.4?nm, giving a core?Cshell structure with an antiferromagnetic core, and a shell with a net magnetic moment under an applied magnetic field.     

Pell-type equations and class number of the maximal real subfield of a cyclotomic field

We investigate the solvability of the Diophantine equation \(x^2-my^2=\pm p\) in integers for certain integer m and prime p. Then we apply these results to produce family of maximal real subfield of a cyclotomic field whose class number is strictly larger than 1.     

Evidence of protonation during the oxidation of some aryl alcohols by permanganate in perchloric acid medium and mechanism of the oxidation processes

The oxidation of benzyl alcohol and methoxy-, chloro-, and nitro- substituted benzyl alcohols by permanganate has been studied in aqueous and acetic acid medium in presence of perchloric acid. The reaction is first-order in [MnO₄^?] and [XC₆H₄CH₂OH], but the order is complex with respect to [H⁺]. Different thermodynamic parameters have been evaluated. The reaction occurs through the protonation of alcohol in a fast preequilibrium followed by a slow rate-determining oxidation step. A two-electron transfer oxidation step has been suggested for benzyl alcohol and chloro- and nitro- substituted alcohols, while the oxidation of methoxy compounds involves a one-electron transfer via a free-radical mechanism. © 1995 John Wiley & Sons, Inc.     

Über die dilatometrisch indizierten Titrationen

The change of the volume caused by adsorption of a fatty acid (e.g. acetic acid, propionic acid) on activated coal is continuously controlled by means of a dilatometrical titration. According to the adsorption isothermes the formation of a mono- and then a dimolecular adsorption layer can be shown. In high concentrated fatty acid a stronger covering of the surface of the adsorbent occurs. A quantitative calculating gives also—with the help of potentiometry—informations about the specific surface area, pore volume and pore radius of the activated coal used.     

Modified electronic charge density of some alkali fluoride crystals

The free ion wavefunctions of alkali fluorides have been modified by considering the effect of crystal lattice. It has been postulated that only the outermost electrons of the ions are affected and the neighbouring ions have been approximated as point charges. A Hartree-Fock-Slater scheme has been utilised to determine the wavefunction through a numerical procedure. The corresponding modified electronic charge densities of the ions indicate the extension of the positive ion radii and contraction of the negative ion radii in the crystal.     

Kinetics of oxidation of ethanol by potassium permanganate in perchloric acid medium

The oxidation of ethanol by permanganate has been found to obey the rate law v=k[MeCHO][MnO ₄ ^– ][H⁺]. The results are compared with those found for chromium (VI) oxidation of the same substrate.

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V=k[MeCHO][MnO ₄ ^– ][H⁺]. , (VI).

     

A multi-objective design optimization strategy as applied to pre-mixed pre-vaporized injection systems for low emission combustors

This paper presents a multi-objective optimization procedure as applied to the design of the injection system of a Lean Pre-mixed Pre-vaporized combustion chamber. The optimizer drives an Artificial Neural Network in a repeated analysis scheme in order to simultaneously reduce NO_X and CO pollutant emissions. The ANN is trained with a few three-dimensional high resolution reactive viscous flow simulations, carried out with a reliable and robust CFD code. Results, obtained in a four-dimensional state space, demonstrate the validity of the overall procedure with truly moderate computational costs.