Comparative Bioavailability of Diltiazem in Prolonged-Release Oral Preparations

This study was conducted to compare the bioavailability of two prolonged-release pharmaceutical forms containing 300 mg of diltiazem. The test formulation is a new design of tablets with a hydrophilic matrix, and the reference formulation is capsules containing prolonged liberation microgranules, in the same dose, that are commercially available in the pharmaceutical market. Diltiazem plasma concentrations were analyzed by high-performance liquid chromatography (HPLC), which involves solid-phase extraction for plasma sample preparation. Twelve healthy volunteers participated in the study, which had a single-dose, two-treatment, two-sequence-crossover, randomized design. The preparations were compared using pharmacokinetic parameters such as the area under the plasma concentration-time curve AUC_(0-36), peak plasma concentration C_max, and C_max/AUC_(0-36) ratio as a measure for the absorption rate. No statistically significant difference was observed for any of the parameters, and the 90% confidence intervals calculated for the ratio of the logarithmically transformed AUC_(0-36) and C_max/AUC_(0-36) values of both formulations were within the bioequivalence limit of 0.80-1.25. Moreover, an in vitro study of dissolution according to USP 23 was conducted, and the in vitro parameters were calculated.     

Enzymatic removal of free and conjugated sterols forming pitch deposits in environmentally sound bleaching of eucalypt paper pulp

Free and conjugated sterols are among the main compounds responsible for pitch deposition in the manufacture of wood chemical pulps, making difficult the implementation of totally chlorine free bleaching (TCF) and closure of bleach plant circuits. In this work, the suitability of oxidative enzymes in efficiently removing sterols from eucalypt pulps is revealed. The enzymatic treatment was applied as an additional stage of an industrial-type TCF sequence for bleaching eucalypt kraft pulp. The pulp obtained after oxygen delignification was treated with a high-redox potential and thermostable fungal laccase using 1-hydroxybenzotriazole as an enzyme mediator. This pulp was further submitted to chelation and peroxide stages and compared with a control TCF pulp obtained using chemical reagents. The composition of the lipophilic extractives in the pulps and the corresponding liquids after the different stages was analyzed by gas chromatography and gas chromatography--mass spectrometry. Free sitosterol and sitosterol esters and glucosides, the major lipophilic compounds in eucalypt pulps, were completely removed during the laccase-mediator treatment. Only some intermediate products from sitosterol oxidation remained after the laccase stage, as well as in the final pulp. Pulp brightness was also improved due to the simultaneous removal of lignin by the laccase-mediator treatment.     

Deposition and characterization of MgO/Si gate stacks grown by molecular beam epitaxy

In this article, the deposition and characterization of amorphous MgO films grown on Si (001) using molecular beam epitaxy is reported. In order to ensure amorphous films, low substrate temperatures (200 °C) and high oxygen pressures were used (up to 5 × 10^− 3 Pa). Both atomic and molecular oxygen species were used at different pressures. Films ranging in thickness from 3 nm till 30 nm were grown and characterized using structural and electrical methods.The dielectric constant deduced from this thickness series corresponds to 8.74 close to the bulk value of 9.8. The best equivalent oxide thickness value observed for this series - grown under high oxygen pressure - corresponds to 1.2 nm for a current density measured at V_FB − 1 V of 0.1 A/cm². The films grown with atomic oxygen display a lower capacitance and lower leakage compared to the films grown using molecular oxygen. This is due to the appearance of a thin SiO₂ interface layer which is also responsible for the high defect density observed in the capacitance-voltage measurements. Upon annealing both types of films in forming gas for 15 min at 450 °C, the capacitance decreases further while the leakage increases. This change is assigned to the appearance of the lower bandgap (6.6 eV), lower dielectric constant (6.6) phase of silicate, MgSiO₃. Furthermore a V_FB shift of − 0.6 V is observed and is related to the appearance of oxygen vacancies as Mg diffuses into the SiO₂ interface layer.     

Study of the incorporation of native and microencapsulated chia seed oil on pasta properties

The present work studied the effect of the incorporation of encapsulated chia seed oil on the cooking quality of dry pasta. Pasta morphology and oil distribution in the samples were studied. No significant variations were determined in cooking parameters as optimal cooking time, cooking loss and texture of cooked pasta with the incorporation of the encapsulated oil, but significant differences were determined in uncooked pasta texture and variables that describe water interaction, such as water absorption and swelling index. In addition, the incorporation of microencapsulated oil avoided oxidative deterioration, showing a protective effect and preventing the formation of hydroperoxide radicals in pasta preparation, storage and cooking procedures (compared with free oil-containing pasta), resulting in a safer product. Storage at modified atmosphere exerts an additional protective effect on oil, enhancing the effect of the microcapsules. Microencapsulation proved to be an effective technology that preserves oil quality in ω-3 rich pasta.     

Versatile Thermochromic Supramolecular Materials Based on Competing Charge Transfer Interactions

Stimuli‐responsive supramolecular materials are of paramount importance for a broad range of applications. It is essential to impart versatility, sustainability, and scalability into these materials. Herein the authors report the design and synthesis of a new class of thermochromic supramolecular materials, which can easily be processed from water via a reversible sol–gel transition. The supramolecular materials are composed of a bis‐bipyridinium acceptor, a π‐electron‐rich naphthalene derivative donor, and halogen counterions. Long helical nanofibers can be assembled in water, gelating at room temperature. Inked designs, thin films, and aerogels are solution‐processed to exhibit thermochromic behavior based on competing π → π* and n → π* charge transfer interactions. By using different π‐electron rich donors, and counterions, the authors demonstrate that both the color observed at room temperature and at high temperatures can be tailored. The results open up the door to develop novel amphiphile‐based thermochromes with water processability and a large tunable color palette.     

Volatile Profile Characterization of Extra Virgin Olive Oils from Argentina by HS-SPME/GC-MS and Multivariate Pattern Recognition Tools

The distinctive aroma of virgin olive oil is attributed to a large number of chemical compounds of different classes such as aldehydes, alcohols, esters, hydrocarbons, ketones, furans, and other volatile compounds that are not yet identified. The aim of the present study lies in the characterization of compound volatile profile of the most representative olive oil cultivars produced in Argentina. The methodology proposed was based on the development of headspace (HS)-SPME/GC-MS with the subsequent analysis of the chemical fingerprints using a discriminant analysis method and a principal component analysis data compression strategy to distinguish olive oils from different varietal origins. Carboxen/polydimethylsiloxane (75 μm) fiber was the most efficient to trap volatile compounds. Optimization of the SPME conditions was also carried out using multivariate methods. To avoid the influence of factors other than the cultivar, olive trees were cultivated under the same agronomic and pedoclimatic conditions; olive fruits were picked at the same stage of ripeness, and their oils were extracted with the same processing system. Volatile fractions from oils of the analyzed cultivars consisted of a complex mixture of more than 40 compounds. Both quantitative and qualitative differences were found among cultivars. The analytical data association with multivariate analysis constitutes a reliable analytical tool with potential ability to discriminate monovarietal extra virgin olive oil from Argentina.     

Gustatory Responsiveness to Six Bitter Tastants in Three Species of Nonhuman Primates

Gustatory responsiveness of six adult squirrel monkeys, four spider monkeys, and five pigtail macaques to six bitter tastants was assessed in two-bottle preference tests of brief duration (2 min). Animals were given the choice between a 30-mM sucrose solution and defined concentrations of a bitter tastant dissolved in a 30-mM sucrose solution. With this procedure, Saimiri sciureus, Ateles geoffroyi, and Macaca nemestrina were found to significantly discriminate concentrations as low as 0.2, 0.05, and 0.1 mM quinine hydrochloride; 1, 1, and 0.05 mM caffeine; 20, 5, and 1 mM naringin; 5, 2, and 1 mM salicin; 0.01, 0.001, and 0.02 mM sucrose octaacetate; and 0.05, 0.01, and 0.5 mM denatonium benzoate, from the alternative stimulus. With the exception of naringin in the pigtail macaques, all three species rejected all suprathreshold concentrations of all bitter tastants tested. The spider monkeys and the pigtail macaques displayed the lowest taste avoidance thresholds with three of the six tastants each; in contrast, the squirrel monkeys displayed the highest taste avoidance thresholds with four of the six tastants. The across-tastant patterns of taste avoidance thresholds were identical in spider monkeys and squirrel monkeys; both species displayed the following order of sensitivity: sucrose octaacetate > denatonium benzoate > quinine hydrochloride > caffeine > salicin > naringin. All three primate species were more sensitive to the two artificial tastants (sucrose octaacetate and denatonium benzoate) compared to the four naturally occurring tastants. However, the concentrations detected by all three primate species with the four naturally occurring tastants are well below those reported in plants or arthropods consumed by these species suggesting that they may use bitterness as a criterion for food selection.