ALBERT

Description: Due to its low water solubility and slow dissolution rate, genipin was micronized by an antisolvent precipitation process using ethanol as solvent and n -hexane as antisolvent. The effects of various experimental parameters on the mean particle size (MPS) of micronized genipin were investigated. By analysis of variance, only the concentration of the genipin solution has a significant effect on the MPS in genipin micronization. Under the optimum conditions, micronized genipin with an MPS of 1.8 μm was obtained. The micronized genipin was characterized by various methods, e.g., scanning electron microscopy and thermogravimetry. The analysis results indicated that the chemical structure of micronized genipin was not changed, but the crystallinity was reduced. The dissolution rate and solubility of the micronized genipin were 2.08 and 1.64 times that of the raw drug. In addition, the residual amounts of n -hexane and ethanol were less than the International Conference on Harmonization limit for solvents. Micronized genipin with a mean particle size of 1.8 μm was prepared by the antisolvent precipitation process. The chemical structure of micronized genipin remained unchanged, but the crystallinity was reduced. The dissolution rate and solubility of the micronized genipin were 2.08 and 1.64 times that of the raw drug, and the amounts of residual n -hexane and ethanol were lower than the International Conference on Harmonization limit for solvents.

Description: A novel chemical soft-sensor approach for the prediction of the melt index (MI) in the propylene polymerization industry is presented. The MI is considered as one of the important variables of quality that determine the product specifications. Thus, a reliable estimation of the MI is crucial in quality control. An accurate optimal predictive model of MI values with the relevance vector machine (RVM) is proposed, where the RVM is employed to build the MI prediction model; a modified particle swarm optimization (MPSO) algorithm is then introduced to optimize the parameter of the RVM, and the MPSO-RVM model is thereby developed. An online correcting strategy (OCS) is further carried out to update the modeling data and to revise the model's parameter self-adaptively whenever model mismatch happens. Based on the data from a real polypropylene production plant, a detailed comparison is carried out among the least squares support vector machine (LS-SVM), RVM, MPSO-RVM, and OCS-MPSO-RVM models. The research results reveal the prediction accuracy and validity of the proposed approach. A chemical soft-sensor approach for the prediction of the melt index (MI) in the propylene polymeriza-tion industry is presented. The relevance vector machine (RVM) is employed to build the MI prediction model. A modified particle swarm optimization algorithm is then introduced to optimize the parameter of the RVM and an online correcting strategy is carried out to update the modeling data.

Description: Using the PPMLR-MHD global simulation model, we examined the Kelvin-Helmholtz (K-H) instability at the low-latitude boundary layer (LLBL) under northward interplanetary magnetic field (IMF) conditions with various solar wind speeds (400, 600, and 800 km/s). The spatial distribution of the K-H wave power in the equatorial plane shows two distinct power populations, referring to the two modes of K-H surface waves. The spatial evolution of K-H instability at the boundary layer is classified into four phases: quasi-stable, exponential growth, linear growth, and nonlinear phases. The boundary layer is quasi-stable near the subsolar point region. The K-H instability starts at about 30° longitude, and grows exponentially with a spatial growth rate of 0.28∼0.87 RE−1 until ∼45° longitude where the vortices fully develop. At larger longitudes, the instability grows linearly, while the vortices grow in size. From ∼80° longitude to the distant magnetotail, the K-H instability develops nonlinearly and the vortices roll up. The wave frequency, wavelength, and phase speed are given at various spatial points. Model results show that the higher solar wind speed generates K-H waves with higher frequency under the northward IMF, and the wavelengths and the phase speeds increase with the increase of the longitude. Moreover, we made a comparison of the K-H wave periods on Earth's, Mercury's and Saturn's magnetopauses by a proposed prediction method.

Description: Slow shock formation and structure associated with magnetic reconnection are investigated in the presence of sub-Alfvénic shear flow using a compressible resistive MHD model. It is found for the first time that one or two pairs of the slow shocks are formed in the inflow region away from the reconnection separatrices within compressible resistive MHD. The distributions of the slow shocks depend largely on the plasma beta and the shear flow velocity that lead to the increase of magnetic reconnection rate. One pair of the slow shocks is formed for β = 0.2 and two pairs of the slow shocks are generated for β = 1.0 with the shear flow velocity in the range 0.6 VA to 0.9 VA. For high plasma beta (β = 5.0), there is no slow shock formed outside the reconnection separatrices. The results can be applied to interpret slow shock observations at the dayside magnetopause.

Description: The dielectric and ferroelectric characteristics of ( Sr x Ba 1− x ) Nb 2 O 6 unfilled tungsten bronze ceramics have been investigated together with the structure. The dielectric and ferroelectric characteristics of the present ceramics vary significantly with x , and the A1/A2-sites occupancy has been determined as the primary parameter governing this variation tendency. Ba ions tend to occupy A2-sites, Sr ions tend to occupy A1-sites, and one A1-site is empty. When the ratio of Sr / Ba is close to 1:4 (where four A2-sites are just occupied by Ba ions, and one A1-site is occupied by Sr ion while another A1-site is empty), the normal ferroelectric transition is observed with one anomaly in the tanδ– T curve ( x  = 0.25). When the ratio of Sr / Ba is far away from 1:4, the typical relaxor behavior is indicated together with three anomalies in the tanδ– T curve ( x  = 0.75). The incommensurate oxygen octahedral tilting and A-site random distribution are considered to be the structure origins for the relaxor ferroelectricity and low temperature dielectric relaxations.

Description: A novel chemical soft-sensor approach for the prediction of the melt index (MI) in the propylene polymerization industry is presented. The MI is considered as one of the important variables of quality that determine the product specifications. Thus, a reliable estimation of the MI is crucial in quality control. An accurate optimal predictive model of MI values with the relevance vector machine (RVM) is proposed, where the RVM is employed to build the MI prediction model; a modified particle swarm optimization (MPSO) algorithm is then introduced to optimize the parameter of the RVM, and the MPSO-RVM model is thereby developed. An online correcting strategy (OCS) is further carried out to update the modeling data and to revise the model's parameter self-adaptively whenever model mismatch happens. Based on the data from a real polypropylene production plant, a detailed comparison is carried out among the least squares support vector machine (LS-SVM), RVM, MPSO-RVM, and OCS-MPSO-RVM models. The research results reveal the prediction accuracy and validity of the proposed approach. A chemical soft-sensor approach for the prediction of the melt index (MI) in the propylene polymeriza-tion industry is presented. The relevance vector machine (RVM) is employed to build the MI prediction model. A modified particle swarm optimization algorithm is then introduced to optimize the parameter of the RVM and an online correcting strategy is carried out to update the modeling data.

Description: Polyelectrolyte-enhanced ultrafiltration was investigated for rhenium(VII) recovery from aqueous solutions by using polyquaternium-6 (PQ6) as a complexing agent. The effects of the operating parameters on the permeate flux ( J ) and the rhenium rejection coefficient ( R ) were studied. In the process of concentration, J declines slowly and R is about 1. The concentrated solution was used for the decomplexation. It takes 10 min to achieve the decomplexation equilibrium at a chloride ion concentration of 100 mg L –1 . The decomplexation percentage reaches 45.6 %. In the diafiltration process, rhenium is extracted effectively, and the purification of the regenerated PQ6 is satisfactory. The regenerated PQ6 was used to bind rhenium(VII). The binding capacity of the regenerated PQ6 is close to that of fresh PQ6. Polyelectrolyte-enhanced ultrafiltration was originally used to achieve the recovery of rhenium from aqueous solutions with the help of polyquaternium-6. The effects of various operating parameters on the permeate flux and the rhenium rejection coefficient were investigated. The integration of four experiments including concentration, decomplexation, diafiltration and reuse of the regenerated polymer was carried out.

Description: In order to understand the differences in the suspended sediment and total dissolved solid (TDS) yield patterns between the glacial and non-glacial catchments at the headwaters of Urumqi River, Northwestern China, water samples were collected from a glacier catchment and an empty cirque catchment within the region, during three melting seasons from 2006 to 2008. These samples were analyzed to estimate suspended sediment and TDS concentrations, fluxes and erosion rates in the two adjoining catchments. There were remarked differences in suspended sediment and TDS yield patterns between the two catchments. Suspended sediment concentrations were controlled mainly by the sediment source, whereas TDS concentrations were primarily related to the hydrologic interaction with soil minerals. Generally, the glacial catchment had much higher suspended sediment and TDS yields, together with higher denudation rates, than the non-glacial catchment. Overall, glacial catchment was mainly dominated by physical denudation process, whereas the non-glacial catchment was jointly influenced by physical and chemical denudation processes. The observed differences in material delivery patterns were mainly controlled by the runoff source and the glacial processes. The melting periods of glacier and snow were typically the most important time for the suspended sediment and TDS yields. Meanwhile, episodic precipitation events could generate disproportionately large yields. Subglacial hydrology dynamics, glaciers pluck and grind processes could affect erodibility, and the large quantities of dust stored on the glacier surface provided additional sources for suspended sediment transport in the glacial catchment. These mechanisms imply that, in response to climate change, the catchment behavior will be modified significantly in this region, in terms of material flux. This article is protected by copyright. All rights reserved.

Description: [1]  In this paper, the essential technique of Grad-Shafranov (GS) reconstruction is reformulated into an inverse boundary value problems (IBVPs) for Laplace's equation on a circle by introducing a Hilbert transform between the normal and tangent component of the boundary gradients. It is proved that the specified IBVPs have unique solution, given the known Dirichlet and Neumann conditions on certain arc. Even when the arc is reduced to only one point on the circle, it can be inferred logically that the unique solution still exists there on the remaining circle. New solution approach for the specified IBVP is suggested with the help of the introduced Hilbert transform. An iterated Tikhonov regularization scheme is applied to deal with the ill-posed linear operators appearing in the discretization of the new approach. Numerical experiments highlight the efficiency and robustness of the proposed method. According to linearity of the elliptic operator in GS equation, its solution can be divided into twoparts. One is solved from a semi-linear elliptic equation with an homogeneous Dirichlet boundary condition. The other is solved from the IBVP of Laplace's equation. It is concluded that there exists a unique solution for the so-called elliptic Cauchy problem for the essential technique of GS-reconstruction.