Preparation, characterization, and catalytic performance of Pd–Ni/AC bimetallic nano-catalysts

Palladium–nickel (Pd–Ni) bimetallic nano-catalysts supported on activated carbon (Pd–Ni/AC) have been successfully prepared by impregnation method enhanced with ultrasonic. The prepared Pd–Ni/AC catalysts were used for the catalytic hydrodechlorination reaction of bleached shellac and characterized by Fourier-transform infrared spectroscopy, nitrogen adsorption, X-ray diffraction, X-ray photoelectron spectroscopy, field-emission scanning electron microscope, and high-resolution transmission electron microscopy. The results show that Pd–Ni bimetallic structures in catalytic particles with the diameter of 4 and 14 nm were distributed uniformly on AC support, and the lattice fringe spacing in catalytic particles was measured as 0.213 nm which is lying in the region between monometallic Pd (111; 0.225 nm) and Ni (111; 0.203 nm), and that Pd1–Ni1/AC catalyst exhibits the best catalytic hydrodechlorination performance with the dechlorination efficiency of 92.58 wt% while it is used for the hydrodechlorination of bleached shellac, and the optimum catalytic performance is related to the synergistic electronic effect and bimetallic structure of the Pd1–Ni1/AC sample.

Phase Behavior of Doxycycline Hyclate-Incorporated Bleached Shellac In Situ Forming Gel/Microparticle after Solvent Movement

With regard to the periodontal pocket application of in situ forming systems, the understanding the phase behavior after solidification owing to solvent movement could verify the deformability of specimen and its capacity to reside in the artificial periodontal pocket. The aim of this research was to investigate the phase behavior by determining mechanical properties as hardness and elasticity/plasticity ratio with texture analyzer for matrices obtained from drug-free and doxycycline hyclate (DX)-incorporated bleached shellac (BS) in situ forming gel (isg) and –microparticle (ism) after solvent exchange. The solvents for dissolving BS were 2-pyrrolidone (PYR), N-methyl pyrrolidone (NMP) and dimethyl sulfoxide (DMSO). The matrix from isg was less rough and bulge than that of isg. The order of mechanical hardness of transformed system prepared with different solvents was presented as PYR > NMP > DMSO, influenced by phase separation rate and porosity. The systems prepared with NMP and DMSO were more likely plastic or able to adapt its geometry to dynamic changes while that prepared with PYR was elastic. DX-incorporated ism matrix was still governed by the oil in external phase; thus, its consequence was reasonably plastic instead. XRD pattern indicated that the solvent type had no effect on the crystallinity of remained BS after solvent movement. SEM topography revealed sponge-like structure of isg prepared with DMSO and NMP whereas that prepared with PYR exhibited only initiated diminutive pores. The size and density of pores increased by time of isg using different solvents as following DMSO > NMP > PYR, whereas ism matrices had less pore density. The level of porosity of each matrix reflected the mechanical strength that a higher porous structure collapsed easily but a dense matrix considerably resisted to a compression.

Fabrication of Enteric Release Tablet without Coating Process by Using Bleached Shellac

The purpose of this study was to design an enteric release tablet by a simple method of tableting and avoiding the coating process. Polymers which had a protection ability against acid were required for tablet formulation. Bleached shellac was selected as an excipient due to colorless property, a protection ability against acid in upper gastrointestinal tract and release ability in lower gastrointestinal tract. Bleached shellacs in salt and acid forms were dissolved in 12 ml of 95% ethanol and used as a binding agent to get a concentration of 5, 7.5, 10, 12.5, 15, 17.5 and 20 %w/w of total formulation. 60% lactose, 30% Avicel pH 102 and 10% paracetamol (model drug) were mixed and tablets were prepared by wet granulation method with the weight of 550 mg and hardness of 8-10 kg. The tablets were evaluated for their disintegration and drug release at pH 1.2 and 6.8 and kept at 40 °C, 75%RH for 6 months. The findings showed that the disintegration and amount of release were dependent on type and concentration of bleached shellac. Only the bleached shellac in salt form could protect the release of drug at pH 1.2 for 2 h and could release completely at pH 6.8 but not in acid form. After 6 months of storage, 15% bleached shellac in salt form could still protect against acid and complete release at pH 6.8 for 4 h. Although the bleached shellac showed protection ability against acid, it could not comply with the required criteria of enteric release tablet. Further study is hence required. However, the stability test of tablets prepared with bleached shellacs in salt form could show protection against acid and complete release at pH 6.8 after 6 months of storage. Bleached shellacs in salt form as a binding agent showed a good approach for the fabrication of enteric release tablets without coating process by using a proper concentration of bleached shellac. Therefore, the attempt to design an enteric tablet by a simple method and avoiding the coating process is achieved.