The fate of Si and Fe while nuclear glass alters with steel and clay

The French concept developed to dispose high-level radioactive waste in geological repository relies on glassy waste forms, isolated from the claystone host rock by steel containers. Understanding interactions between glass and surrounding materials is key for assessing the performance of a such system. Here, isotopically tagged SON68 glass, steel and claystone were studied through an integrated mockup conducted at 50 °C for 2.5 years. Post-mortem analyses were performed from nanometric to millimetric scales using TEM, STXM, ToF-SIMS and SEM techniques. The glass alteration layer consisted of a crystallized Fe-rich smectite mineral, close to nontronite, supporting a dissolution/reprecipitation controlling mechanism for glass alteration. The mean glass dissolution rate ranged between 1.6 × 10−2 g m−2 d−1 to 3.0 × 10−2 g m−2 d−1, a value only 3–5 times lower than the initial dissolution rate. Thermodynamic calculations highlighted a competition between nontronite and protective gel, explaining why in the present conditions the formation of a protective layer is prevented.

Solid Dispersions as a Technological Strategy to Improve the Bio-Performance of Antiparasitic Drugs with Limited Solubility

Albendazole (ABZ) and benznidazole (BZL) are drugs with low solubility used in parasitic infections treatment. In this research, solid dispersion (SD) technology was used to enhance ABZ and BZL performance by increasing their dissolution rate and solubility. SDs were prepared by the fusion method, employing Poloxamer 407 (P407) as carrier to disperse 32 of BZL or 50% w/w of ABZ. Furthermore, physical mixtures (PM) of P407 and either ABZ or BZL were also prepared, and then SDs and PMs were characterized. Dissolution tests of SDs, PMs and commercial formulations (CF) of ABZ and BZL were carried out and dissolution profiles were analyzed with the lumped mathematical model, which allowed parameters of pharmaceutical relevance to be obtained. The results indicated that ABZ SD presented an initial dissolution rate (IDR) 21-fold and 11-fold faster than PM and CF, respectively, while the IDR of BZL SD was 2.5-fold and 4.5-fold faster than PM and CF, respectively. For BZL formulations, the time required to reach 80% dissolution of the drug (t80%) was 4 (SD), 46 (PM), and 239 min (CF), while the dissolution efficiency (DE) at 30 min was 85 (DS), 71 (MF) and 65% (FC). For ABZ formulations, t80% was 2 (SD), value not reached (PM) and 40 min (CF), while the DE at 30 min was 85 (SD), 36 (MF) and 65% (CF). The SDs developed notably increased the dissolution rate, in consonance with the values obtained from the pharmaceutical parameters, which could lead to faster absorption and, consequently, increase the bioavailability of these drugs.

Control of Drug Dissolution Rate from Film Dosage Forms Containing Valsartan

Film dosage forms (FDs) containing valsartan (VST), a popular antihypertensive drug, were prepared using a casting method with sodium alginate and other polysaccharides as the film base. Drug dissolution profiles of the FDs were investigated in limited medium. The FDs were 170–200 μm thick and were easy to handle. All FDs immediately swelled and disintegrated in the medium. About 23% of the VST incorporated into the FD prepared with 1.5% sodium alginate dissolved at 5 min. The initial dissolution rate of VST increased upon the addition of chitosan to the film base; this effect was not observed in the case of chitin. On the other hand, the rate apparently decreased upon modification with alginic acid. In addition, the solubility of VST in the dissolution medium was changed by the addition of chitosan or alginic acid. FDs prepared with polysaccharides are useful for simplifying the administration of drugs to patients, and the drug dissolution rate from FDs can be controlled by modification.

Role of Particle Size in Tea Infusion Process

Two different types of CTC (Crush, Tear and Curl) teas were used for infusion kinetics study. Infusion kinetics for these and their ground and sieved fractions were studied over a 15-min period at 60°C and 80°C. Samples were analyzed using UV-Vis spectroscopy. Results of infusion have been interpreted in terms of gallic acid equivalence (GAE). Fractions with smaller particle size show faster infusion. First-order rate constants for largest and smallest fractions were 0.257–0.685 min−1, respectively, at 60°C. A quasi-steady-state model was developed, which determines initial dissolution rate, diffusion rate from actual infusion rate and hence rate controlling step. At 80°C, the infusion rate of the 0.33 mm granules was found to be 98% of the dissolution rate as compared to 68% in case of 1.99 mm granules. The diffusivity values were found to be 2.23×10−10 m2/s and 4.34×10−10 m2/s at 60°C and 80°C, respectively.

Improved Water-Solubility of Phytosterol by Hydroxypropyl-β-Cyclodextrin

Phytosterol has been shown to lower the serum cholesterol concentrations, but its low solubility in water restricts its application. In this study, hydroxypropyl-β-cyclodextrin was used to improve the water-solubility of phytosterol. Phase solubility study pointed out the formation of 1:1 inclusion complexes between phytosterol and hydroxypropyl-β-cyclodextrin. The initial dissolution rate was remarkedly improved in the first two minutes. The suitable solvent and temperature for complex formation was n-butanol and 40°C.