Ferromagnetic core coil hysteresis modeling using fractional derivatives

Nonlinear Dynamics - The modeling of a ferromagnetic core coil magnetic hysteresis has been considered. The measurement basis consisted of waveforms that have been recorded for various levels of...     

Beyond Oxides: Nitride as a Ligand in a Neutral IrIXNO3 Molecule Bearing a Transition Metal at High Oxidation State

Theoretical calculations utilizing relativistic ZORA Hamiltonian point to the conceivable existence of an IrNO₃ molecule in C_3v geometry. This minimum is shown to correspond to genuine nonavalent iridium nitride trioxide, which is a neutral analogue of cationic [IrO₄]⁺ species detected recently. Despite the presence of nitride anion, the molecule is protected by substantial barriers exceeding 200 kJ mol⁻¹ against transformations leading, for example, to global minimum (O=)₂Ir−NO, which contains metal at a lower formal oxidation state.     

The influence of Lewis acid catalyst on the kinetic and molecular mechanism of nitrous acid elimination from 5-nitro-3-phenyl-4,5-dihydroisoxazole: DFT computational study

Chemistry of Heterocyclic Compounds - The molecular mechanism of nitrous acid elimination from 5-nitro-3-phenyl-4,5-dihydroisoxazole systems has been explored using DFT computational study. It was...     

Being uncertain in thin layer chromatography—Some thoughts about latent details in the retention estimation

This paper deals with some important (but often neglected) details about the uncertainty of retention measurement in thin layer chromatography, the propagation of uncertainty during computing simple and more complex values from the retention data, ending in influence of the retention uncertainty onto the regression estimates during extrapolation and lipophilicity estimation. Theoretical considerations are tested on data from previous study. It can be concluded that when TLC spots are broad and the retention uncertainty exceeds about 0.02 of R_F value, the uncertainty should be taken into the account in further computations.     

Tetrahydrophthalic esters of prednisolone

The two biologically active isomers of prednisolone tetrahydrophthalate have been studied by X-ray diffraction methods. The compounds crystallize in the orthorhombic system in the space groupP2₁2₁2₁, with similar lattice parameters. The isomers differ both in configuration [(1′S),(6′R) isomerA and (1′R),(6′S) isomerB] and conformation of the thetetrahydrophthalic part of the molecules. Cell parameters of isomerA:a=9.595(2),b=14.465(2),c=18.988(3) Å andB:a=9.114(2),b=14.283(6),c=20.398(5) Å. The O(3) carbonyl oxygen atom interactsvia hydrogen bonds with three neighboring molecules accepting hydrogen bonds from two hydroxyl groups and one carboxylic group. Additional short intermolecular C?H…O type contacts occur in the structure of theB isomer, which has a somewhat larger unit cell and significantly higher melting point.