Search

The purpose of this investigation was to improve the solubility and oral bioavailability of daidzein via preparing nanosuspensions (NS) with steric stabilizers, electrostatic stabilizers, or a combination of both. Based on particle size and zeta potential, daidzein NS stabilized by HP-β-CD, soy lecithin, HP-β-CD + soy lecithin, TPGS, TPGS + SBE-β-CD, SDS, or HPMC E5 + SDS were generated and characterized by scanning electron microscopy, powder X-ray diffraction, and Fourier transform-infrared spectroscopy. In addition, the stability, cytotoxicity, solubility, dissolution, and pharmacokinetics of NS were evaluated. The resulting daidzein NS were physically stable and biocompatible and presented as regular shapes with homogenous particle sizes of 360–600 nm and decreased crystallinity. Due to the increased solubility and dissolution rate, the oral bioavailability of daidzein NS in rats was 1.63–2.19 times greater than that of crude daidzein. In particular, among the investigated seven daidzein NS formulations, daidzein NS prepared with the costabilizers HPMC E5 + SDS is an optimal formulation for increased daidzein bioavailability. The present study proposes that the combined usage of steric and electrostatic stabilizers is a promising strategy for improving the bioavailability of water-insoluble flavonoid compounds by an NS approach.

Crushed gangue, an inhomogeneous and discontinuous medium, is accompanied with the absorption and dissipation of energy under compression. In order to study the compressive deformation and energy dissipation of gangue in the loading process under conditions of different particle sizes, loading rates, and first-time stress loads, a SANS testing machine and steel cylinder were used to conduct experiments in this paper. The following conclusions were drawn from the investigation: 1) The gangue underwent three separate stages of compressive deformation, which included rapid, slow, and stable; 2) The energy density of the gangue increased nonlinearly as the strain increased, and the dissipated energy accounted for 10%, 20%, and 70% of the total energy, respectively, of the three compressive deformation stages; 3) Particle size and loading rate had significant effects on the deformation and energy dissipation of the gangue. The smaller the particle size or loading rate were, the more energy was required to produce the same level of deformation; 4) When the second stress load was smaller than the first-time stress load, the strain of the gangue increased approximately linearly. When the second stress load was greater, the strain of the gangue showed a logarithmic increase with the stress. Furthermore, under a greater first-time stress load, the gangue presented smaller strain under secondary compression, showed more resistance to deformation, and consumed more energy to produce the same deformation.

The mass ratio is defined to describe the quantity ratio of solid materials backfilled into the stope and raw coal mined out when using solid backfill coal mining technology (SBCMT), and it is a direct control index guaranteeing the backfilling effect in this technology. Design of the backfill body’s compression ratio (BBCR) relies on goal of backfilling coal mining and corresponding equations, while BBCR is strictly controlled by mass ratio. Based on the mechanism that backfilling body controls the movement of overlying strata, the paper establishes the relation equation of mass ratio and BBCR. As for solid material directly affect the design value of mass ratio in SBCMT, tamping arm’s tamping force is the base of implementing index control on mass ratio and backfilling process is the approach of implementing index control on mass ratio, further study on functional relationships between mass ratio and key parameters of backfilling process shows that, with fixed solid backfill material and tamping force, more times of tamping, smaller natural repose angle and higher pile height contribute to a bigger mass ratio. On this basis, this paper establishes the method and design flow of mass ratio and proposes engineering control measures at last. The actual measurement of mass ratio at backfill working face in Zhaizhen Coal Mine shows that, when the solid backfill material is selected as gangues and tamping force is designed as 2 MPa, then the number of tamping times is 5–8, tamping angle is 5°–35°, natural repose angle is 35° and the pile height is 1.8–2.2 m, the mass ratio is controlled to the average value of 1.25, which is higher than designed value of 1.15; furthermore, a bigger mass ratio contributes to better BBCR control and backfilling effect.

A local and parallel algorithm based on the multilevel discretization is proposed in this paper to solve the eigenvalue problem by the finite element method. With this new scheme, solving the eigenvalue problem in the finest grid is transferred to solutions of the eigenvalue problems on the coarsest mesh and a series of solutions of boundary value problems by using the local and parallel algorithm. The computational work in each processor can reach the optimal order. Therefore, this type of multilevel local and parallel method improves the overall efficiency of solving the eigenvalue problem. Some numerical experiments are presented to validate the efficiency of the new method., Comment: 21 pages, 9 figures

The local a priori estimate for the finite element approximation is essential for underlying the local and parallel technique. It is well known that the constant coefficients in the inequality is independent of the mesh size. But it is not so clear whether the constant depends on the scale of the local subdomains. The aim of this note is to derive a new local a priori estimate on the general scale domains. We also show that the dependence of the constant appearing in the local a priori estimate on the scale of the subdomains., Comment: 11 pages, 0 figures