Influence of the Rancimat Apparatus Operating Parameters on Oxidative Stability Determination of Cold-Pressed Camelina and Hemp Seed Oil

The study investigates the impact of operating parameters such as temperature (90, 100, 110, 120 °C), airflow rate (10, 15, 20 L h⁻¹), and sample weight (3, 6, 9 g) on the oxidative stability of cold-pressed camelina and hemp seed oils using the Rancimat apparatus. Conducted analysis indicates a significant influence of temperature on oils' induction time. Moreover, higher airflows should be selected at high analysis temperatures. Based on the calculated parameters of the oxidation kinetics, it was shown that hemp oil has higher activation energy values than camelina oil. Response surface methodology (RSM) indicates that to minimize the determination time of camelina oil oxidation, the following analysis conditions should be selected: sample weight (SW) = 33.5 g, airflow (AF) = 20 L h⁻¹, and temperature (T) = 120 °C. However, for hemp oil, these parameters should be SW = 5.56 g, AF = 15 L h⁻¹, T = 120 °C. Sample mass does not significantly impact oils induction time, which depends mainly on the temperature and airflow. Practical applications: The conducted research shows that the parameters of the cold-pressed camelina and hemp oils oxidative stability have to be determined experimentally. The determined parameters for assessing the oxidative stability will reduce the analysis time and the possibility of interpolating the obtained result at different temperatures and analysis parameters.     

Spray-dried nanoparticle-loaded pectin microspheres for dexamethasone nasal delivery

Abstract

In this study, we present the development of an innovative dry powder dexamethasone (Dex) nasal delivery system comprising Dex-loaded lipid/alginate nanoparticles incorporated within pectin microspheres (Dex/NPs-loaded pectin microspheres; DNM). DNM microspheres were characterized by the mean diameter of 2.76?±?0.10?µm, zeta-potential of –36.2?±?1.1?mV, and drug loading of 3.3?±?0.3%. The morphology study revealed irregular microsphere surface forming external voids. In contact with simulated nasal fluid, DNM microspheres demonstrated desirable property of moderate swelling and ensured stronger mucoadhesion compared with conventional Dex-loaded pectin microspheres. The strategy of Dex incorporation within the lipid/alginate NPs resulted in prolonged Dex release in relation to Dex being directly entrapped within the conventional pectin microspheres. DNM microspheres showed excellent biocompatibility and rendered Dex permeation across the selected epithelial cell model similar to that of Dex solution. In conclusion, balanced biopharmaceutical properties of the proposed nasal Dex delivery system provides the potential for prolonged contact time with nasal mucosa, prolonged therapeutic effect, and improved patient compliance.     

The Temperature Uniformity During Air Drying of a Colloidal Liquid Droplet

ABSTRACT

The mathematical analysis for drying of individual droplets containing dissolved or suspended solids has been given significant importance due to the increasing popularity of the spray drying operation in the production of various chemicals, ceramics, drugs, food, and dairy powders as well as nanoparticles. The physical and biological qualities of the final products primarily depend on the history experienced by the droplet within the dryer. It is, therefore, desirable to ‘estimate’ the droplet's behavior and various characteristics such as moisture content and temperature profiles accurately. In the literature, several models have been presented to estimate moisture and temperature profiles inside a particle considering various assumptions. One common assumption is the uniform temperature distribution within the droplets being dried. The present article has presented an estimation procedure to evaluate the temperature distribution within a porous skim milk droplet to determine whether the uniform temperature distribution assumption is reasonable. Here, the surface-center temperature differences were estimated by considering the one-dimensional, unsteady-state heat conduction equation for a spherical droplet. Shrinkage of droplets was taken into consideration during modeling. A new concept of the Biot number has also been applied in the current article to assist in the determination of the rate-limiting process.     

Effect of immobilization of titanocene catalyst in aralkyl imidazolium chloroaluminate media on performance of biphasic ethylene polymerization and polyethylene properties

1-(2-Phenylethyl)-3-methylimidazolium and 1-benzyl-3-methylimidazolium chloroaluminates, [Ph-C₂mim][AlCl₄] and [Bzlmim][AlCl₄], were applied as media of the Cp₂TiCl₂ catalyst for biphasic ethylene polymerization. The studied aralkyl ionic liquids ensure greater stability of the catalyst at higher temperatures and more regular morphology of the produced polyethylene than analogous 1-n-alkyl-3-methylimidazolium chloroaluminates. The alkylaluminium compound participates in the termination reaction of the polymer chain. The catalyst is stable and enables recycling of the ionic liquid phase in the consecutive polymerization reactions. The [Ph-C₂mim][AlCl₄] ionic liquid and AlEt₂Cl alkylaluminium compound turned out to be the most suitable for the biphasic process. The influence of the kind of ionic liquid, alkylaluminium compound (AlEt₂Cl and AlEtCl₂), activator/catalyst molar ratio, reaction temperature, reaction time and catalyst recycling on the polymerization performance as well as polyethylene properties such as molecular weight (M _w ), polydispersity, melting temperature, crystallinity degree, bulk density and particle size is presented.     

The Uneven Rate of the Molecular Evolution of Gene Sequences of DNA-Dependent RNA Polymerase I of the Genus Lamium L

RNA polymerase type I (plastid-encoded polymerase, PEP) is one of the key chloroplast enzymes. However, the rpo genes that encode its subunits (rpoA, rpoB, rpoC1 and rpoC2) are relatively rapidly evolving sequences. The aim of this study was to investigate the rate of the molecular evolution of rpo genes and to evaluate them as phylogenetic markers on the example of the genus Lamium L. (Lamiaceae). The analyzed genes were shown to differ in the level of variation, rate of intragenic mutations, phylogenetic informativeness, and in the impact of these mutations on the properties of encoded peptides. Destabilizing effects of the positive pressure were observed in all genes examined coding for PEP enzyme. We have demonstrated the relationship between mutations fixed by positive selection and the separation of phylogenetic lines within the genus Lamium. The study showed also that the rpo genes were reliable phylogenetic markers, useful in the reconstruction of interconnections of species belonging to the same genus. Of the four tested genes, the most promising phylogenetic marker was rpoA gene, while the least useful gene appeared to be rpoC1.     

High temperature monoclinic-to-tetragonal phase transition in magnesium doped lanthanum ortho-niobate

Magnesium doped lanthanum ortho-niobate (La_0.98Mg_0.02NbO₄) was prepared by the molten salt synthesis method. X-ray diffraction and dilatometry methods were used to study high temperature behavior of the ceramic material. Special attention was paid to the phase transition between the monoclinic and tetragonal phases. The values of spontaneous strain on the basis of unit cell parameter, obtained by Rietveld refinement, have been calculated as well as Landau order parameter. The thermal expansion coefficient (TEC) of La_0.98Mg_0.02NbO₄ was determined to be 12×10^?6 1/K and 8×10^?6 1/K below and above 500 °C, respectively.     

Electromagnetic properties of aluminosilicate‐filled polymer composites of poly(vinyl alcohol)–poly(vinyl pyrrolidone)

Nanocomposites of aluminocilicate are of growing interest not only because they offer exceptional reinforcement at very low filler concentrations, but also because of their electromagnetic properties and natural origin. Aluminosilicate‐filled biodegradable composites of poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) (PVP) were prepared by a conventional solvent casting technique using glass plates as the casting surfaces. The aluminosilicate used in this study is a multicomponent natural clay material. Its average particle size is 23–24 nm. The dielectric and magnetic properties of composite materials of PVA‐PVP and aluminosilicate were investigated in wide frequency ranges from 1 MHz to 1 GHz. The complex permittivity spectra (ε* = ε′ – jε″) had a relaxation type frequency dispersion with an ill‐defined broad resonance line width of the dielectric losses (ε″). The magnetic properties of composites are very low and are independent of the filler concentration. The new nanobiocomposites are brick red in color and weakly ferromagnetic in nature. POLYM. COMPOS., 26:739–744, 2005. © 2005 Society of Plastics Engineers     

Synthesis and evaluation of liquid amine‐terminated polybutadiene rubber and its role in epoxy toughening

Epoxy resin is widely used for coatings, adhesives, castings, electrical insulation materials, and other applications. However, unsolved problems still remain in its applications. The main problem is low toughness: cured epoxy resin is rather brittle, with poor resistance to the propagation of cracks derived from the internal stress generated by shrinkage in the cooling process from cure temperature to room temperature. The objective of this study was to improve the flexibility and toughness of diglycidyl ether of bisphenol A based epoxy resin with a liquid rubber. For this purpose, amine‐terminated polybutadiene (ATPB) was synthesized. The product was characterized by Fourier transform infrared and NMR spectroscopy and elemental analysis. ATPB‐modified epoxy networks were made by curing with an ambient‐temperature curing agent, triethylene tetramine. We varied the epoxy/liquid rubber compositions to study the effect of toughener concentration on the impact and thermal properties. Higher mechanical properties were obtained for epoxy resins toughened with 1 phr ATPB. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2446–2453, 2005     

A Photoexcited Porphyrin System as a Biomimetic Catalyst for D-limonene Biotransformation

A photoexcited porphyrin system has been found to be an efficient catalyst for D-limonene biotransformation. The catalyst showed high selectivity in hydroxylation of D-limonene. The best catalyst for limonene biotransformation was 5,10,15,20-Tetraphenylporphyrin (H₂TPP), which gave the highest accumulation of carvone and an unknown product with a verbenone-like mass spectrum. The highest conversion yield of these products was favoured at 1:2 molar ratio of H₂TPP to limonene. Some factors affecting the biotransformation yield were also investigated. Maximal yield of carvone was obtained in the medium containing 90% of the substrate, within the period of 18–36 h. Mechanism involved in limonene biotransformation catalysed by H₂TPP is also discussed.