The Effect of Powder Blend on Drug Release Mechanisms of Hydrophobic Starch Stearate Matrix Tablets

Free hydroxyl groups of glucose monomer of starch substituted with steroyl group by chemical modification leads to the formation of starch stearate (SS). Modification changes the nature from hydrophilic to hydrophobic and thus used as controlled release excipient. In present study, SS was evaluated as release modifying polymer and MCC, Lactose, Dicalcium phosphate (DCP) and combinations of these were used to evaluate effect on drug release of Verapamil hydrochloride (VH) and Diclofenac sodium (DS). FT-IR studies of polymer with VH and DS have shown no significant drug:polymer interactions. Decrease in in-vitro drug dissolution was observed with increase in polymer concentration. Cumulative drug released for DS (hydrophobic) was more sustained than hydrophilic drug (VH). Drug release from formulations containing 30%w/w of SS after 8h was 81.61 (for VH) and 25.08% (for DS). DCP retarded drug release more when used alone. After 8h % drug release from formulations containing 30%w/w of SS was 49.86 (VH) and 24.19 (DS). The use of lactose alone increased the drug release and combination of DCP:Lactose in equal proportion with 15 %w/w SS sustained more i.e. 42.62% (VH) drug release at the end of 8h

Random matrix ensemble with random two-body interactions in presence of a mean-field for spin one boson systems

For $m$ number of bosons, carrying spin ($S$=1) degree of freedom, in $\Omega$ number of single particle orbitals, each triply degenerate, we introduce and analyze embedded Gaussian orthogonal ensemble of random matrices generated by random two-body interactions that are spin (S) scalar [BEGOE(2)-$S1$]. The embedding algebra is $U(3) \supset G \supset G1 \otimes SO(3)$ with SO(3) generating spin $S$. A method for constructing the ensembles in fixed-($m$, $S$) space has been developed. Numerical calculations show that the form of the fixed-($m$, $S$) density of states is close to Gaussian and level fluctuations follow GOE. Propagation formulas for the fixed-($m$, $S$) space energy centroids and spectral variances are derived for a general one plus two-body Hamiltonian preserving spin. In addition to these, we also introduce two different pairing symmetry algebras in the space defined by BEGOE(2)-$S1$ and the structure of ground states is studied for each paring symmetry.Comment: 22 pages, 6 figure

Thermalization in one- plus two-body ensembles for dense interacting boson systems

Employing one plus two-body random matrix ensembles for bosons, temperature and entropy are calculated, using different definitions, as a function of the two-body interaction strength \lambda for a system with 10 bosons (m=10) in five single particle levels (N=5). It is found that in a region \lambda \sim \lambda_t, different definitions give essentially same values for temperature and entropy, thus defining a thermalization region. Also, (m,N) dependence of \lambda_t has been derived. It is seen that \lambda_t is much larger than the \lambda values where level fluctuations change from Poisson to GOE and strength functions change from Breit-Wigner to Gaussian.Comment: 7 pages, 4 figure

Spectral Distribution Studies of fp shell nuclei with modified Kuo--Brown Interaction

The structure of nuclei in the lower half of fp shell is investigated by the spectral distribution method using the modified Kuo-Brown interaction. This interaction recently showed success in reproducing observed properties through detailed shell model studies. Spectral distribution studies avoid explicit diagonalization and hold promise for applications to astrophysics.Comment: Latex, 19 pages, 1 figure, to be published in Physical Review

Occupancy and structural changes in upper f-p shell nuclei

We use spectral distribution methods to calculate proton occupancies in ground states of nuclei in the range A=60-80, and show that these results indicate structural changes around N=40-44. Nuclear Structure Spectral distribution calculations of ground state proton occupation numbers in Zn, Ge, Se, and Kr nuclei

Onset of chaos in finite interacting Boson systems with F-spin

For m bosons, carrying spin (f = 1 2) degree of freedom, in Ω single particle levels which are doubly degenerate, one-plus two-body Embedded Gaussian Orthogonal random matrix Ensemble which conserves spin (F) [BEGOE(1 + 2)-F] is defined and spectral properties are examined. Using mean field defined by random single particle energies, for fixed-(m,F) BEGOE(1 + 2)-F, density of states being close to Gaussian, we analyze spectral fluctuation properties, like Nearest Neighbour Spacing Distribution (NNSD) and Dyson-Mehta (Δ3) statistic, as a function of λ- the two-body interaction strength. Numerical calculations are used to demonstrate that for very small value of λ, NNSD and Δ3 are found close to Poisson form and they move steadily to GOE form as λ increases. Moreover, spin dependence of the transition point λC is obtained. It is also verified using periodogram analysis that BEGOE(1 + 2)-F spectra shows 1/f–noise behaviour