Purpose: the aim of this work was to investigate the influence of hydroxypropyl methylcellulose (HPMC) on the phase transformation and release profile of carbamazepinenicotinamide (CBZ-NIC) cocrystal in solution and in sustained release matrix tablets.Methods: The polymorphic transitions of the CBZ-NIC cocrystal and its crystalline properties were examined by differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD), Raman spectroscopy, and scanning electron microscopy (SEM).Results: The apparent CBZ solubility and dissolution rate of CBZ-NIC cocrystal were constant in different concentrations of HPMC solutions. In a lower percentage of HPMC in the matrix tablets, the CBZ release profile of the CBZ-NIC cocrystal was nonlinear and declined over time. With an increased HPMC content in the tablets, the CBZ-NIC cocrystal formulation showed a significantly higher CBZ release rate in comparison with the other two formulations of CBZ III and the physical mixture.Conclusions: Because of a significantly improved dissolution rate of the CBZ-NIC cocrystal, the rate of CBZ enteringinto solution is significantly faster than the rate of formation of the CBZ-HPMC soluble complex in solution, leading to a higher supersaturation level of CBZ and subsequently precipitation of CBZ dihydrate.
Hydrogen (H 2 ) fuel production from hazardous contaminants is not only of economic importance but also of significance for the environment and health. Hydrogen production is exemplified in this work by using bismuth sulfide (Bi 2 S 3 ) sandwiched in between zinc sulfide (ZnS) and zinc oxide (ZnO) as dual-heterojunction photoelectrode to photoelectrochemically extract H 2 from sulfide-and sulfite-containing wastewater, which is emitted in enormous quantities from the petrochemical industries. The H 2 evolution rate over the ZnS/Bi 2 S 3 /ZnO photoelectrode under solar illumination amounts to 112.8 μmol cm −2 h −1 , of which the photocurrent density in the meantime reaches 10.7 mA cm −2 , by far exceeding those reported for additional Bi 2 S 3 -based counterparts in the literature. Such superior performance is ascribed on one hand to the broadband sunlight-harvesting ability of Bi 2 S 3 that gives rise to respectable photoexcited electron−hole pairs. These photogenerated charge carriers are subsequently rectified by the built-in electric field at the ZnS/Bi 2 S 3 and Bi 2 S 3 /ZnO heterojunctions to flow in the opposite directions to well circumvent the recombination losses and, most importantly, in turn contribute substantially to the H 2 evolution reaction.
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