In situ kinetics study of the formation of organic nanoparticles by fluorescence lifetime imaging microscopy (FLIM) along a microfluidic device

In this study, a three-dimensional hydrodynamic focusing microfluidic method is presented that allows full control of the nano-precipitation process of adamantyl mesityl BODIPY (4,4-difluoro-3,5-di-(adamantyl)-8-mesityl-4-bora-3a,4a-diaza-s-indacene) (Adambodipy). The precipitation is achieved by combining a central Adambodipy organic flow with a mixture of water and a cationic surfactant, creating a non-solvent precipitation method. The flow and mixing were simulated using COMSOL Multiphysics^® 3.4. A good agreement between theory and experiment was obtained for the flow velocity, concentration fields and the subsequent precipitation kinetics. Fluorescence lifetime imaging was used to visualize the precipitation domains following the changes in fluorescence lifetime. The lifetime decreases from 6.1 ns for the molecules down to 0.9 ns for nanoparticles. A principal components analysis of the successive fluorescence decay curves showed that the process could be adequately modeled using three components, which can be attributed to monomers (single molecule), clusters (nuclei) and nanoparticles.     

Coexistence of Superconductivity and Antiferromagnetism in Heavy-Fermion Intermetallic Compound CeRhIn5

An interference of heavy-fermion superconductivity (SC) and antiferromagnetism (AFM) has been studied in the framework of the periodic Anderson model with the superexchange interaction between localized electrons. It has been shown that pressure-induced energy change of the localized states leads to modifying antiferromagnetic and superconducting order parameters. Conditions have been found for the coexistence of SC and AFM in the model. Theoretical results of the pressure effects on the ground state character of the heavy-fermion systems are in good agreement with experimental data for a rare-earth intermetallic compound CeRhIn₅. The divergence of the effective electron mass produced by suppressing the long-range antiferromagnetic order has also been analyzed in the same framework.     

Modeling the recovery patterns from solid phase extraction purification of secoisolariciresinol diglucoside,p-coumaric acid glucoside,and ferulic acid glucoside from microwave-assisted flaxseed extracts

Flaxseed extracts obtained by microwave-assisted extraction (MAE) were cleaned of leftover salts from hydrolysis by solid phase extraction (SPE). The SPE set up was affordable, non-automated and vacuum-driven. The recovery patterns of secoisolariciresinol diglucoside (SDG), p-coumaric acid glucoside (PCouAG), and ferulic acid glucoside (FerAG) were modeled in two stages using regression procedures (p < 0.05). At stage one, the recovery patterns were predicted as a function of SPE eluent concentration in ethanol (10–50%). At stage two, the accuracy of the predictions was increased by enlarging the SPE eluent regressor's range (0–100% ethanol in water) and arranging the solvent system into three practical elution groups. The groups 1, 2 and 3 reflected the major loss, the major recovery and the minor loss of SDG, respectively. Second degree polynomial regression models were fitted for accurately predicting the recoveries of compounds. Microwave-assisted extracts obtained from 0.6 and 1.5 g defatted flaxseed meal were purified; the total SDG recoveries from the SPE funnel were 97.8 and 99.8%; and the SDG amounts obtained were 8.54 and 20 mg, respectively. The HPLC analysis of eluates pooled into practical groups allows for significant reductions in HPLC analysis time and solvent consumption which could have a positive impact on future purification studies. The results of this study allow for designing simplified, efficient and economical pilot scale studies for the purification of SDG from flaxseed extracts.     

Polyunsaturated Fatty Acid Concentrates of Carp Oil: Chemical Hydrolysis and Urea Complexation

The aims of this study were to compare three treatments in the chemical hydrolysis reaction of bleached oil from carp (Cyprinus carpio) heads and to obtain polyunsaturated fatty acid concentrates by urea complexation. The three treatments were carried out with different oil:ethanol molar ratios. In the treatment with a 1:39 molar ratio, a higher yield of free fatty acids was found. These fatty acids were submitted to urea complexation (−10 °C for 20 h, and urea–fatty acid ratio of 4.5–1). There was a 31.4% increase in monounsaturated and polyunsaturated fatty acids (MUFA and PUFA) content and a 75% decrease in saturated fatty acids (SAF) content. An increase of 85.4% in the EPA + DHA content was found. The non-urea complexing fraction can be considered a rich source of MUFA and PUFA with a total amount of 88.9%.     

Brewer’s spent grain as a functional ingredient for breadsticks

Brewer’s spent grain (BSG) was evaluated for its potential as a functional baking ingredient. Scanning electron microscopy (SEM) was used to examine the microstructure of BSG and wheat flours. Baked snacks (breadsticks) were prepared using 15%, 25% and 35% BSG and evaluated for their baking quality and fibre and protein content (over a period of 3 months). The addition of BSG altered the baking characteristics of the breadsticks by affecting their structure and texture. The snacks appeared to lack in cellular structure and crispiness. However, they had quite a stable shelf‐life, as changes in texture, moisture and a_w progressed at a low rate. Addition of 25% and 35% BSG significantly increased the protein content of the snacks, and addition of 15% BSG more than doubled the content of dietary fibre in the samples.     

Modeling the reliability of a group membership protocol for dual-scheduled time division multiple access networks

We present reliability models for a group membership protocol designed for TDMA networks such as FlexRay, a protocol that is likely to become the de facto standard for next generation automotive networks. The models are based on discrete-time Markov chains and consider a comprehensive set of fault scenarios. Furthermore, they are parametric allowing for a sensitivity analysis. The results, obtained by a numeric solution of the models using the PRISM model-checker, show that they are computationally practical for realistic configurations and that the GMP can achieve reliability levels in the range required for safety critical applications.     

Synthesis of mechanisms using evolution of associated dissipative systems

The paper deals with the new approach of the kinematical synthesis based on the reformulation of the synthesis computations as a time evolution of the nonlinear dynamical dissipative system. The synthesis/optimization objective functions are constructed based on the network of mechanism positions within the desired workspace. All synthesized parameters of the mechanism are in the associated dynamical system introduced as time-varying and generally different in the different positions. The important points and/or important lines are equipped with the fictitious masses and/or moments of inertia, the differences of parameters generates the correction forces, and the gradual dissipation of the kinetic energy is ensured by dampers connected between the inertial frame and the masses (sky-hook concept). The correction forces couple the auxiliary dynamical subsystems created in different positions. The nonzero correction forces are generated as long as the values of the corresponding parameters across the positions differ. The synthesis process is realized as the time evolution of such a system. The main advantage of the method for solving mechanisms?? synthesis is that it uses the unassembled configurations of the mechanisms by evolution of the time varying parameters. The mechanism search thus smoothly goes through the space of system parameters without inefficient penalization of the unassembled configurations. This space provides possible valuable solution of the more robust kinematical synthesis of the mechanisms. The applications for the different types of synthesis tasks and optimization of different objective functions like the optimization of the mechanism transmission or the multi-objective optimization of dexterity measure and the built-up space are straightforward, as described within the presented examples. The efficiency of the method can be improved using several re-activations of the evolution process.     

Determination of Fexofenadine in Tablets by Capillary Electrophoresis in Free Solution and in Solution with Cyclodextrins as Analyte Carriers

ABSTRACT

Capillary electrophoresis (CE) methods for the determination of fexofenadine (FEX) in commercial pharmaceuticals were developed. It was demonstrated that FEX could be effectively analyzed in free solution cationic CE at low pH. Another analytical approach studied was based on cyclodextrin (CD) modified CE where highly charged CD derivatives served as analyte carriers. In this way, the separation range was spread to physiological pH region and a CE analysis of FEX, present actually in its zwitterionic form, could be accomplished. Several parameters affecting the separations were studied, including the type and concentration of carrier ion, counterion, analyte carrier, and pH of the buffer. The methods based on the free solution CE and CD-modified CE were compared each other, validated, and applied for the determination of FEX in tablets.