NUMERICAL MODEL FOR WAX DEPOSITION IN OIL WELLS

A liquid-solid compositional model that uses an equation of state has been developed to predict the phenomenon of wax deposition in model oil wells. Numerical solutions to the conservation equations for Newtonian-to-non-Newtonian flow regimes show temperature, radial mass flux and wax deposition profiles as a function of time and position in the pipe, using realistic pressure and temperature profiles of a model well. Such rheologic regime changes are dictated by thermodynamic arguments.     

Preface for buccal drug delivery theme issue

During the past years, buccal drug delivery has attracted the attention of researchers looking for alternative delivery routes of administration. As an alternative to oral drug delivery, the buccal mucosal route avoids the passage through the acidic gastric environment, intestinal and bacterial enzymatic activity, absorption issues associated with the intestinal epithelium (e.g. P-glycoprotein efflux), and the first pass metabolism of the liver. Therefore, the buccal route could be a good delivery route for macromolecules and other drugs not compatible with the gastrointestinal tract environment. This “Buccal Drug Delivery” special edition of Drug Development and Industrial Pharmacy aims to bring together a range of different aspects relevant to the growing field of buccal drug delivery. The special edition includes thorough reviews of the literature, as well as original research articles touching on most prominent features related to buccal drug delivery systems, such as the move toward the use of nanotechnology in different ways to facilitate buccal drug delivery with the potential to prompt future product developments.     

Phytochemical Composition and in Vitro Analysis of Nopal (O. Ficus-Indica) Cladodes at Different Stages of Maturity

This study aimed to determine the phytochemical profile and nutraceutical properties of nopal cladodes (Opuntia ficus-indica) at different stages of maturity. Medium-age cladodes showed the highest total saponins, phytosterols, and indigestible fiber, as well as the highest in vitro antioxidant capacity and digestive enzymes inhibitory activity. Furthermore, these cladodes presented the highest content of p-hydroxybenzoic acid, p-coumaric acid, rutin, narcissin, nicotiflorin, β-sitosterol, and sitosteryl-3-β-glucopyranoside, as well as several amino acids, organic acids, and fatty acids. Whereas young cladodes contained the highest concentration of condensed and hydrolyzable tannins. These results demonstrated that maturity affects the nutritional and nutraceutical properties of nopal cladodes.     

Prandtl–Tomlinson-Type Models for Coupled Molecular Sliding Friction: Chain-Length Dependence of Friction of Self-assembled Monolayers

Tribology Letters - Most asteroids with a diameter larger than $$\sim 300 \ {\mathrm{m}}$$ are rubble piles, i.e., consisting of more than one solid object. All asteroids are rotating but almost...     

Preparation and Properties of Physically Modified Banana Starch Prepared by Alcoholic‐Alkaline Treatment

Granular cold‐water‐soluble (GCWS) starches were prepared from banana starch treating it with 40 and 60% aqueous ethanol at two controlled temperatures (25 and 35 °C). GCWS starches prepared at 25 °C and with 40 and 60% aqueous ethanol had the lowest cold‐water solubility, that prepared with 40% aqueous ethanol at 35 °C and stored at room temperature showed low tendency to retrogradation, as assessed by transmittance. Solubility and swelling profiles were similar for GCWS starches and the freeze‐thaw stability of GCWS starches was increased as compared with native starch. The apparent viscosity of GCWS banana starches was higher than that of its native starch counterpart.     

Structural Properties of Starches Dissolved by Microwave Heating

Starches from various botanical sources, presenting different amylose-amylopectin levels, were solubilized with microwave heating and analyzed by high-performance size exclusion chromatography coupled online with multi-angle laser light scattering and refractive index detectors. The molar mass and gyration radius distributions were obtained. Analysis of the particle scattering factors (angular dependence of the scattered light) showed small differences in the internal structure of the samples solubilized during 35, 50 and 70 s. However, the slight differences in the internal structure of samples studied were revealed using Kratky plot. Structure degradation was found when heating of the sample in the microwave oven increased. Structural properties influence the functionality of starches in food products.