Spontaneous formation of polylactide stereocomplex microspheres containing metal ions

Linear poly(l ‐lactides) (PLLAs ) and poly(d ‐lactides) (PDLAs ) with M _n in the range 2000 ? 4300 containing a different number and placement of carboxyl groups were obtained via cationic ring‐opening polymerization and post‐polymerization functionalization. PLA stereoisomers (PLLA ‐(COOH )_x and PDLA ‐(COOH )_x , where x = 1 ? 3) were used for the investigation of stereocomplexation in solution performed in the presence of metal cations such as Ca²⁺, Mg²⁺, Zn²⁺, Fe³⁺. Spherical microparticles with a diameter in the range 0.7 ? 3.0 µm were obtained in all cases which was confirmed on the basis of scanning electron microscopy (SEM ) analysis. The microsphere size and homogeneity were analyzed depending on the stereocomplexation conditions and the molecular weight as well as the number of carboxyl end groups in the PLLA and PDLA used for stereocomplexation. The PLA microspheres obtained were analyzed by Fourier transform IR spectroscopy, wide angle X‐ray spectroscopy and energy‐dispersive X‐ray spectroscopy methods which confirmed the presence of metal cations inside. The application of regular microspheres with metal ions as drug delivery systems is considered. © 2016 Society of Chemical Industry     

Polyhydroxyalkanoate‐based drug delivery systems

Microbial polyhydroxyalkanoates (PHAs) have been a subject of significant research interest in the past few decades. The recent development of novel functionalized PHAs has opened up new possibilities to combine the good biocompatibility of PHA‐based drug delivery systems to, for example, improve drug loading and release properties, targeting or imaging functionalities. This mini‐review presents some recent scientific developments in the preparation of functionalized PHAs, PHA–drug and PHA–protein conjugates, multifunctional PHA nanoparticles and micelles as well as biosynthetic PHA particles for drug delivery. These developments in combination with the generally excellent biocompatibility of PHA materials are expected to further expand the interest in PHA materials for drug delivery and other therapeutic applications. © 2016 Society of Chemical Industry     

The application of organophosphorus flame‐retardants in epoxy resin

The influence of two novel aryl phosphate mixtures on fire retardancy and the thermal stability of epoxy resin were studied. Combustion behavior, decomposition pathway, and thermal and thermo‐oxidative degradation of the epoxy resin were examined by using the limiting oxygen index, vertical burning test (UL‐94), cone calorimeter test, thermogravimetric analysis, and thermogravimetry coupled with Fourier‐transform infrared spectroscopy. The morphology of the residues from the degradation of flame‐retarded epoxy resins was investigated by using scanning electron microscopy. Data from the cone calorimeter test demonstrated that the total heat evolved, heat release rate, and peak heat release rate decreased significantly when the epoxy resin contained these retardants. Moreover, a 20 wt% of both phosphate mixtures in the epoxy resin allowed for a satisfactory oxygen index (30–33%) and for UL‐94 V2 to be achieved. The condensed‐phase and gas‐phase actions of these aryl phosphate flame‐retardants are proposed as the mode of flame‐retardancy in epoxy resins. J. VINYL ADDIT. TECHNOL., 23:142–151, 2017. © 2015 Society of Plastics Engineers     

Ozone Synthesis and Decomposition in Oxygen-Fed Pulsed DBD System: Effect of Ozone Concentration,Power Density,and Residence Time

The process of ozone production in pure oxygen was studied. It was shown how the ozone concentration changes along the discharge gap, both during its generation and decomposition processes. The effect of ozone inlet concentration, power, and gas residence time on ozone concentration was analyzed. It has been shown that concentrated ozone is easily decomposed at very low discharge powers, i.e., when the increase of the average gas temperature in the gap is negligibly small. It was hypothesized that the most intense decomposition takes place in the microdischarge channels, because the process of gas heating in the gap begins inside them.     

Nonstationary convective drying of raspberries,assisted by microwaves and ultrasound

This study was conducted to investigate the drying characteristics and quality of raspberries dried in non-stationary conditions. Seven drying programs were carried out, including convective (CV) drying as a reference. The non-stationary-hybrid programs were based on continuous CV drying with intermittent microwave and ultrasound assistance. The Midilli–Kucuk model was used successfully to describe the drying kinetics of raspberry fruits. The comparison between moisture ratio, drying rate, diffusion coefficient, energy consumption, and quality analysis, showed that non-stationary-hybrid drying improves process kinetics and results in less color change, higher anthocyanin retention, and better texture profile analysis characteristics with optimal energy usage than other methods. In addition, the physical and microstructural changes occurred during different drying processes were discussed.     

Physicochemical,Antioxidative, and Sensory Properties of Refined Rapeseed Oils

Physicochemical characteristics, antioxidant capacity (AC), and sensory quality of rapeseed oils available on the Polish market were analyzed and compared. The fatty acid composition (saturated fatty acids = 6.91–7.58%, monounsaturated fatty acids = 64.14–66.14%, and polyunsaturated fatty acids = 27.22–30.17%), color (T420 = 54.5–83.8%), amounts of free fatty acids (0.02–0.07%), primary (PV = 0.04–2.04 meq O₂ kg⁻¹) and secondary (AV = 1.02–3.21) oxidation products, phosphorus (0.38–1.62 mg kg⁻¹), chlorophyll (0.002–0.068 mg kg⁻¹), and polycyclic aromatic hydrocarbons (Σ4PAH = 0.00–2.50 μg kg⁻¹) in the commercial rapeseed oils meet the requirements of the European Food Regulation and Codex Alimentarius standards. Moreover, total phenolic content (TPC = 40.3–467.9 mg SA kg⁻¹) in the studied oils significantly differs from each other. However, the AC of rapeseed oils was analyzed using the novel iron oxide nanoparticle-based (IONP = 5552.1 − 18,510.2 μmol TE/100 g) method and the modified ferric reducing antioxidant power (FRAP = 55.7–280.3 μmol TE/100 g), cupric reducing AC (CUPRAC = 79.6–784.0 μmol TE/100 g), 2,2-diphenyl-1-picrylhydrazyl (DPPH = 185.7–516.7 μmol TE/100 g), and 2,2′-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS = 465.6–2142.6 μmol TE/100 g) assays. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were applied for discrimination of the refined rapeseed oils based on fatty acid composition, physicochemical parameters, AC, and sensory properties.     

Determination of Acoustical Parameters of Aqueous Solution of Kolliphors Binary Mixtures Using Density,Speed of Sound,Viscosity, and Surface Tension Measurements

Measurements of density, speed of sound, and surface tension as well as viscosity of aqueous Kolliphor® ELP (ELP) and Kolliphor® RH 40 (RH40) solutions as well as binary mixtures at different surfactant mole fractions were made at 293 K to investigate their aggregation behavior. The free volume, internal pressure, and molar cohesive energy were calculated and compared to the specific acoustic impedance and intermolecular free length to obtain qualitative information about the character of interactions between the surfactant molecules in the mixture through the water phase.     

Expected and unexpected plastic behavior at the micron scale: An in situ μLaue tensile study

The study of mechanical properties in micron- and submicron-sized metal crystals raises fundamental questions about the influence of size on different aspects of plasticity. In situ characterization of the microstructure evolution during loading is necessary to understand the physics underlying crystal deformation. In situ μLaue diffraction is able to provide unique statistical information on the evolution of type and density of stored dislocations. Here we show macroscopically expected and unexpected plastic behavior at low strains, observed during in situ μLaue tensile tests on micron-sized, single slip oriented Cu samples. Regardless of the initial behavior, a steady state is reached which qualifies a technical yield criterion at the micron scale.