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Open access

Ehsan GOodarzi, Javad Farhoudi and Naser Shokri

Flow Characteristics of Rectangular Broad-Crested Weirs with Sloped Upstream Face

The hydraulc characteristics of flow over rectangular broad-crested weirs with varying upstream slopes were experimentally studied. A series of laboratory experiments was performed to investigate the effects of changing upstream slopes from 90° to 75°, 60°, 45°, 30°, 22.5°, 15°, and 10° on the flow surface pattern, discharge coefficient values, approach velocity profile and flow separation zone. In addition, a new mathematical relationship for water surface profile and a new correction factor to estimate discharge coefficient over weirs with various upstream slopes were introduced. The results showed decreasing upstream slopes from 90° to 10° leading to increasing discharge coefficient values and dissipation of the separation zone.

Open access

Mir-Ali Molaei, Karim Osouli-Bostanabad, Khosro Adibkia, Javad Shokri, Solmaz Asnaashari and Yousef Javadzadeh

Abstract

The study was conducted to enhance the dissolution rate of ketoconazole (KCZ) (a poorly water-soluble drug) using the liquisolid technique. Microcrystalline cellulose, colloidal silica, PEG400 and polyvinyl pyrrolidone (PVP) were employed as a carrier, coating substance, nonvolatile solvent and additive in the KCZ liquisolid compact formulation, respectively. The drug-to-PEG400 and carrier-to-coating ratio variations, PVP concentration and aging effects on the in vitro release behavior were assessed. Differential scanning calorimetry (DSC) and X-ray powder diffraction (XRD) data revealed no alterations in the crystalline form of the drug and the KCZ-excipient interactions within the process. The load factor and the drug release rate were significantly enhanced compared to directly compressed tablets in the presence of the additive. Increasing the PEG400-to-drug ratio in liquid medications enhanced the dissolution rate remarkably. The dissolution profile and hardness of liquisolid compacts were not significantly altered by keeping the tablets at 40 °C and relative humidity of 75 % for 6 months. With the proposed modification of the liquisolid process, it is possible to obtain flowable, compactible liquisolid powders of high-dose poorly-water soluble drugs with an enhanced dissolution rate.