Role of cellulose ether polymers on ibuprofen release from matrix tablets

Cellulose derivatives are the most frequently used polymers in formulations of pharmaceutical products for controlled drug delivery. The main aim of the present work was to evaluate the effect of different cellulose substitutions on the release rate of ibuprofen (IBP) from hydrophilic matrix tablets. Thus, the release mechanism of IBP with methylcellulose (MC25), hydroxypropylcellulose (HPC), and hydroxypropylmethylcellulose (HPMC K15M or K100M) was studied. In addition, the influence of the diluents lactose monohydrate (LAC) and β-cyclodextrin (β-CD) was evaluated. Distinct test formulations were prepared containing: 57.14% of IBP, 20.00% of polymer, 20.29% of diluent, 1.71% of talc lubricants, and 0.86% of magnesium stearate as lubricants. Although non-negligible drug-excipient interactions were detected from DSC studies, these were found not to constitute an incompatibility effect. Tablets were examined for their drug content, weight uniformity, hardness, thickness, tensile strength, friability, porosity, swelling, and dissolution performance. Polymers MC25 and HPC were found to be unsuitable for the preparation of this kind of solid dosage form, while HPMC K15M and K100M showed to be advantageous. Dissolution parameters such as the area under the dissolution curve (AUC), the dissolution efficiency (DE_{20 h}), dissolution time (t 50%), and mean dissolution time (MDT) were calculated for all the formulations, and the highest MDT values were obtained with HPMC indicating that a higher value of MDT signifies a higher drug retarding ability of the polymer and vice-versa. The analysis of the drug release data was performed in the light of distinct kinetic mathematical models—Kosmeyer-Peppas, Higuchi, zero-, and first-order. The release process was also found to be slightly influenced by the kind of diluent used.     

Mixed isogeometric analysis of strongly coupled diffusion in porous materials

In this paper, we develop a mixed isogeometric analysis approach based on subdivision stabilization to study strongly coupled diffusion in solids in both small and large deformation ranges. Coupling the fluid pressure and the solid deformation, the mixed formulation suffers from numerical instabilities in the incompressible and the nearly incompressible limit due to the violation of the inf‐sup condition. We investigate this issue using subdivision‐stabilized nonuniform rational B‐spline (NURBS) elements, as well as different families of mixed isogeometric analysis techniques, and assess their stability through a numerical inf‐sup test. Furthermore, the validity of the inf‐sup stability test in poromechanics is supported by a mathematical proof concerning the corresponding stability estimate. Finally, two numerical examples involving a rigid strip foundation on saturated soil and a swelling hydrogel structure are presented to validate the stability and to demonstrate the robustness of the proposed approach.     

Guidelines for the Integration of Autonomous UAS into the Global ATM

The growing social and economic interest in new unmanned aircraft systems (UASs) applications demands that UASs operate beyond the segregated airspace they are currently able to fly. However, UAS operations in non-segregated airspace should be regulated by aeronautical authorities before UASs can share airspace with manned aircraft. It has been a challenge for regulatory authorities to define these regulations because they do not understand the topic well. In addition, there is no consensus in the academic community regarding UAS concepts, such as taxonomy and features. This study proposes guidelines that could support UAS regulations for the future integration of autonomous UASs into the Global Air Traffic Management System (GATM). These guidelines are based on three viewpoints: the aircraft, the piloting autonomous system (PAS) and the integration of autonomous UASs into non-segregated airspace. We recommend that the UAS concept should be based on genuine aeronautical precepts, which would be directly applied, without terminology or conceptual adaptations, for the integration of these aircraft into airspace according to the GATM paradigm.     

Polystyrene nanoparticles as surfactant carriers for enhanced oil recovery

It is well known that oil recovery processes can be increased by surfactant solution injections in the reservoir. However, the high adsorption of this type of compounds on the reservoirs rocks surface is one of the factors that have been preventing the Enhanced Oil Recovery (EOR) development and the economicity of the process. This work presents the synthesis of cross‐linked polystyrene nanoparticles (PSNP) and their evaluation as surfactant carriers, able to percolate through the reservoirs pores and to deliver it at the water/oil interface. The nanoparticles were synthesized by emulsion polymerization of styrene and divinylbenzene in the presence of nonylphenol ethoxylate‐10 (NF‐10EO) or sodium dodecyl sulphate. Photon Correlation Spectroscopy and Interfacial Tension results gave support to the initial supposition that the nanoparticles would swell when in contact with the oil phase, releasing the surfactant at the interface. The nanoparticles obtained with NF‐10EO were able to reduce the water/oil interfacial tension to values that were similar to the ones obtained with the aqueous solution of NF‐10EO. The results suggest that the PSNP have a great potential to be used as surfactant carriers in EOR. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43789.     

Cationic starch derivatives as reactive shale inhibitors for water‐based drilling fluids

One of the major problems associated with the use of water‐based drilling fluids is the interaction of water with specific rock formations, such as shales, and the consequent swelling of reactive clays that may be present in that type of rock. Several types of clays reactivity inhibitors have been used by the oil industry, and the most effective ones are the cationic polyelectrolytes, such as the poly(diallyldimethylammonium chloride) (PDADMAC). However, this polyelectrolyte is very toxic. In this work, a series of cationic starch derivatives with different cationic degrees were synthesized with the objective of evaluating their potential as environmentally correct shale reactivity inhibitors. The results showed that the synthesized derivatives presented a good capacity of adsorption on bentonite and an efficient inhibition of the shale reactivity. The derivative with an intermediate cationic degree presented the best performance. In the tests with the formulated fluids this derivative provided an intact cuttings recovery of 84.8% and a total recovery of 92.3%. These values are very close to those found for the PDADMAC additive, therefore indicating that this cationic starch derivative presents a good potential as inhibitor of the shale reactivity. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46621.     

Effect of Chitosan-Coated Alginate Microspheres on the Permeability of Caco-2 Cell Monolayers

ABSTRACT

Alginate microspheres were prepared by emulsification/internal gelation and coated with chitosan. The ability of chitosan-coated alginate microspheres to increase the paracellular transport across Caco-2 cell monolayers was evaluated in comparison to uncoated microspheres and chitosan solutions. Transport studies were performed by using a permeability marker, Lucifer Yellow (LY), and by measuring the transepithelial electric resistance (TEER) variations. Furthermore, the occurrence of cytotoxic effects was assessed by evaluating neutral red uptake in viable cells and lactate dehydrogenase (LDH) release from damaged cells. A 3-fold increase on LY permeability was obtained for coated microspheres when compared to chitosan solutions. TEER variations were in agreement with permeability results. Chitosan solutions exhibited a dose-dependent toxicity, but coated microspheres did not decrease the viability of cells. Chitosan-coated alginate microspheres have potential to be used as carriers of poorly absorbable hydrophilic drugs to the intestinal epithelia and possibly increase their oral bioavailability.     

Monitoring of thread quality when tapping nodular cast iron with TiN-coated HSS cutting taps

Tapping is a widely employed but complex manufacturing process in which a multi-toothed tool, known as a tap, cuts a mating thread when driven into a hole. In this paper, the experiments, statistical analysis and the on-line implementation of a new thread quality monitoring system are presented for a tapping process in high-speed conditions. A multivariate statistical process control chart, for each tap, is presented based on the principal components of the torque directly measured from spindle motor drive. The on-line implementation of the multivariate chart provides tap wear warnings and alarms before the process starts producing unacceptable screw threads. The system is cost-effective since the tapping process can be run automatically without any operator intervention, does not require intrusive sensors, does not result in false negatives (defects) and provides an acceptable number of false positives.     

Impact of plant extracts upon human health: A review

Abstract

With the increase in evidences directly linking diet and health, several foodstuffs, such as phenolic rich fruits and vegetables, have emerged as possessing potential health benefits. Plants, given their fiber and phenolic content (and their intrinsic biological potential), have long been considered as contributing to health promotion. Therefore, the present work aimed to review the existing evidences regarding the various potential benefits of plant extracts’ and plant extract-based products’ consumption, with emphasis on in vivo works and epidemiological studies whenever available. Overall, the information available supports that, while there are indications of the potential benefits of plant extracts’ consumption, further human-based studies are still needed to establish a true cause-effect.     

Health promoting properties of blueberries: a review

Abstract

With the strengthening of the link between diet and health, several foodstuffs have emerged as possessing potential health benefits such as phenolic rich fruits and vegetables. Blueberries, along with other berries, given their flavonoid and antioxidant content have long since been considered as a particularly interesting health promoting fruit. Therefore, the present work aimed to compile the existing evidences regarding the various potential benefits of blueberry and blueberry based products consumption, giving particular relevance to in vivo works and epidemiological studies whenever available. Overall, the results demonstrate that, while the evidences that support a beneficial role of blueberry and blueberry extracts consumption, further human based studies are still needed.     

Purification of β‐Galactosidase by Ion Exchange Chromatography: Elution Optimization Using an Experimental Design

β‐Galactosidase is an enzyme industrially used to hydrolyze milk lactose, generating dairy products destined for people intolerant to this sugar. Its importance is due to its galactosiltransferase activity. The effects of elution pH and salt gradient volume were evaluated for purification of β‐galactosidase by ion exchange chromatography using an experimental design and response surface techniques. The best conditions for purification of β‐galactosidase were pH 5.5 with an elution volume of 62.8 mL, obtaining a yield of 85.5 % and a 12‐fold increase in the purification factor in a one‐step chromatography process. Purification of β‐galactosidase by application of a single stage of ion exchange and evaluation of the important process parameters using an experimental design provided good results in the recovery and purification factor that could subsequently be scaled up.