Some physico-chemical and thermodynamic characteristics of maize starches hydrolyzed by glucoamylase.

Glucoamylolysis of maize starch at 55 °C has been studied by means of scanning electron microscopy (SEM), wide-angle X-ray diffraction spectroscopy (WAXD), and differential scanning calorimetry (DSC). It was found that hydrolysis is accompanied by changes in thermodynamic parameters of diluted aqueous dispersions of partially hydrolyzed starches. Such changes are ensured by two processes directly from hydrolysis and accompanying annealing. At relatively low degrees of hydrolysis (less than 30%), changes in thermodynamic parameters are mainly controlled by annealing. At the same time, at high degrees of hydrolysis (more than 40%), the main contribution to changes in thermodynamic parameters of partially hydrolyzed starch granules is due to the hydrolysis itself. It has been established that the main controlling parameter is the thickness of crystalline lamellae Lcrl, which, when annealed, increases, but tends to decrease at deeper glucoamylolisis. It has been established that the thickness Lcrl of crystalline lamellae, which increases with annealing, but shows a tendency to decrease with deeper glucoamylolysis is the most representative parameter of changes in maize starch after hydrolysis.

Electron paramagnetic resonance of the excited states of the three-spins-1/2 ZnTPP-3-NOPy complex.

EPR spectra of the excited quartet and doublet molecular states of (tetraphenylporphinato)zinc(II) covalently bounded to 3-(N-nitronyl-notroxide) pyridine stable radical are modeled in terms of the spin-Hamiltonian given by the sum of the contributions from the radical and triplet moieties, and the interaction between them. The later is represented by anisotropic point dipolar and isotropic exchange electron spin-spin interactions. It is shown that the high field (W-band) EPR spectra depend on energy separation between the electronic doublet (D) and quartet (Q) states. This dependence was utilized to estimate the upper limit of the intensity of exchange interaction between the radical and porphyrin moieties.

Crystal environment of impurity Nd3+ ion in yttrium and scandium orthosilicate crystals.

The ESEEM spectroscopy was used to determine positions of the 143Nd3+ impurity ions in Y2SiO5 single crystal. It is established that neodymium ions substitute yttrium ions in the Y2 positions with seven nearest oxygen ions. Crystal field parameters of 143Nd3+ impurity centers in isotopically pure Y228SiO5 and Sc228SiO5 single crystals were determined using data of CW EPR spectroscopy and the known energy level schemes.

Time resolved electron spin resonance of spin correlated micelle confined radical pairs: shape of the anti-phase structure.

A new approach to the theory of the EPR of spin correlated radical pairs (SCRP) is formulated. It is based on spectral exchange methods as applied to the two-site model and takes into account explicitly both the motion of one quantum (transverse magnetization) and two quantum coherences (polarizations) of SCRPs. This innovation allows for the interpretation of anti phase structure (APS) spectral shape asymmetry and for the transformation of the initially created ST0RPM polarization into the APS spectral pattern. The results of this method as applied to micellized spin correlated radical pairs have been compared with the exact numerical solution of the corresponding stochastic Liouville equation and is commented on.

Peculiar manifestation of the dipole-dipole interaction between non-Kramers paramagnetic centers as studied by tunable high-frequency EPR spectroscopy.

EPR spectral shape of non-Kramers paramagnetic centers (PCs) is theoretically analyzed under conditions of saturation. The analysis is performed in a model that includes the spectral diffusion process induced by a random modulation of the dipole-dipole interaction of the paramagnetic centers, by reorientations of magnetic moments. It is shown that around zero magnetic field, a 'hole' might appear in the EPR spectrum. We have also studied experimentally the saturation behavior of the EPR spectrum in Cr2+: Mg2SiO4. The experimental results are interpreted in the framework of the model considered. By comparing simulated and experimental spectra, the paramagnetic relaxation times and the characteristic rate of the spectral diffusion are estimated.