In this research, a new, green and eco-friendly method for the synthesis of spirooxindole derivatives was presented. The reaction was performed at room temperature in the presence of catalytic amounts (4 mol.%) of CuO nanoparticles and products were obtained in high to excellent yields. Low-cost high-efficiency reusable catalyst, short reaction times at room temperature, high to excellent yield and easy purification of products are the main advantages to this protocol. The pronounced advantages of catalyst are expected to create a new pathway for the synthesis of spirooxindoles.ARTICLE HISTORY

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This study details the process of coating theophylline with ethylcellulose using the coacervation technique of microencapsulation. Microencapsulation of theophylline not only renders it sustained-release, but also decreases its gastric irritation and masks the bitter taste (Lin and Yang 1987). The non-solvent addition method was chosen through a literature survey to ascertain various phases of the coacervate (Robinson 1989, Nixon and Wong 1990). A three-phase diagram was used to determine the optimum quantity of each component required. Steps were then carried out to optimize the production. Drug release rates of the prepared microcapsules were determined over 12-h cycles using the U.S.P. dissolution apparatus and the results obtained were compared with those of Knoll's (Germany) sustained-release theophylline capsules. Significant control over the rate of drug released from the developed dosage form was achieved during the experiment time (12 h). It is concluded that the method employed in this study could be effectively used in the preparation of sustained-release theophylline microcapsules capable of releasing their drug content for an extended period of time. Kinetic studies suggested that both the prepared microcapsules and Knoll's product followed Higuchi's model for drug release. Particle size and release data analysis from five consecutive batches prepared in the laboratory indicated suitable reproducibility of the coacervation process.

Introduction. This study aimed to investigate the effects of 3 orthodontic bracket adhesives and 3 resin removal methods on enamel discoloration. Methods. Ninety metal orthodontic brackets were bonded to 90 intact human premolars, using 3 adhesives (total etch composite (Transbond), self-etch composite (OptiBond), and light-curedresin-modified glass ionomer cement (RMGI, Fuji); n = 3 × 30). Each “bracket bonding” group (n = 30) was randomly divided into three subgroups of 10 specimens each, each with a different method of remnant resin removal (using only tungsten carbide burs; using tungsten carbide burs plus Sof-Lex polisher discs; using tungsten carbide burs and Stainbuster burs; n = 3 × 30). After bracket debonding and coffee staining (at 37°C for one week), the color change parameters (Δa, Δb, ΔL, and ΔE) were measured and then analyzed statistically (α = 0.05). Results. All 9 mean ΔE values were significantly greater than 3.7 and 1.0 ( P values ≤0.002, t-test). The effects of composites and resin removal methods on the ΔE parameter (and their interaction) were significant ( P values ≤0.008, two-way ANOVA). There were significant pairwise comparisons between total etch (Transbond) and each of the other composites ( P values ≤0.008, Tukey). Nonetheless, the difference between self-etch (OptiBond) and RMGI (Fuji) was not significant ( P = 0.967 ). There were significant pairwise comparisons between the ΔE parameter of group “Bur + Stainbuster” and ΔE of each of the other methods (both P values ≤0.017). Conclusions. All 9 pairs of adhesives and resin removal techniques will cause quite visible discolorations. Still, self-etch composites or RMGI might be recommended over total etch composites. Moreover, using Stainbuster burs together with tungsten carbide burs is recommended to reduce discoloration. However, the coloration caused by each composite type can change drastically given the following adhesive removal technique used.