Thermal Stability and Crystallization Behavior of Contaminated Recycled Polypropylene for Food Contact

Polypropylene is one of the most widely used polymers, especially in the food packaging industry, which causes negative environmental effects. Recycling is a good option to partially solve this environmental problem. Thus, the polymer was contaminated with a cocktail to simulate the conditions of disposal and recycling following FDA guidelines. The influence of contaminants on recycled PP was analyzed by quiescent and nonquiescent crystallization. It was found that the contaminants alter the crystallization flow since longer induction times were observed for all contaminated samples. Also, the thermal behavior was performed considering that the thermogravimetric (TGA) results indicated an increase in the stability with the presence of contaminants. Therefore, a deep investigation using the induced oxidation time (OIT) and induced oxidation temperature (OITD) was performed. The contaminants play an important role in the crystallization process, as well as, in the degradation of the samples. Furthermore, the use of TGA and DSC as complementary techniques is fundamental to analyze this influence.

Comparison of Aging Resistance and Antimicrobial Properties of Ethylene–Norbornene Copolymer and Poly(Lactic Acid) Impregnated with Phytochemicals Embodied in Thyme (Thymus vulgaris) and Clove (Syzygium aromaticum)

The effects of plant-based extracts on the solar aging and antimicrobial properties of impregnated ethylene–norbornene (EN) copolymer and poly(lactic acid) (PLA) were investigated. In this study, the impregnation yield of polyolefin, lacking in active centers capable of phytochemical bonding, and polyester, abundant in active sides, was measured. Moreover, two different extracts plentiful in phytochemicals—thyme (TE) and clove (CE)—were employed in the solvent-based impregnation process. The effect of thymol and eugenol, the two main compounds embodied in the extracts, was studied as well. Interestingly, oxidation induction times (OIT) for the impregnation of EN with thyme and clove extracts were established to be, respectively, 27.7 and 39.02 min, which are higher than for thymol (18.4 min) and eugenol (21.1 min). Therefore, an aging experiment, mimicking the full spectrum of sunlight, was carried out to investigate the resistance to common radiation of materials impregnated with antioxidative substances. As expected, the experiment revealed that the natural extracts increased the shelf-life of the polymer matrix by inhibiting the degradation processes. The aging resistance was assessed based on detected changes in the materials’ behavior and structure that were examined with Fourier-transform infrared spectroscopy, contact angle measurements, color quantification, tensile tests, and hardness investigation. Such broad results of solar aging regarding materials impregnated with thyme and clove extracts have not been reported to date. Moreover, CE was found to be the most effective modifying agent for enabling material with antimicrobial activity against Escherichia coli to be obtained.

Screening of Anaesthetics in Adult Zebrafish (Danio rerio) for the Induction of Euthanasia by Overdose

Zebrafish are often euthanized by overdose of anaesthesia. However, fish may have aversion towards some anaesthetics, and protocol efficacy varies between species. Using wild type adult Danio rerio, we assessed time to loss of opercular beat, righting, and startle reflexes during induction of anaesthetic overdose by either tricaine (0.5 g/L or 1 g/L), benzocaine (1 g/L), 2-phenoxyethanol (3 mL/L), clove oil (0.1%), isoeugenol (540 mg/L), lidocaine hydrochloride (1 g/L), or etomidate (50 mg/L). Initial screening demonstrated that benzocaine and buffered lidocaine hydrochloride achieved the fastest loss of reflexes. The rapid induction times were confirmed when retesting using larger batches of fish. The fastest induction was obtained with 1 g/L lidocaine hydrochloride buffered with 2 g/L NaHCO3, in which all adult zebrafish lost reflexes in less than 2 min. Next, we monitored signs of distress during benzocaine or buffered lidocaine hydrochloride overdose induction. The results indicated that buffered lidocaine hydrochloride caused significantly less aversive behaviors than benzocaine. Finally, we tested several buffers to refine the lidocaine hydrochloride immersion. The most efficient buffer for euthanasia induction using 1g/L lidocaine hydrochloride was 2 g/L NaHCO3 with 50 mL/L 96% ethanol, inducing immobility in less than 10 s and with only 2% of adult zebrafish displaying aversive behaviors during treatment.

Chemical and physical properties of fats produced by chemical interesterification of tallow with vegetable oils

This study aims at manufacturing structured lipids by chemical interesterification (CI) of beef tallow with corn, canola and safflower oils individually at various tallow blend ratios (60, 70, 80%) and catalyst concentrations (0.75, 0.875, 1%). Several physical and chemical properties of interesterified products were determined and data were analyzed using univariate and multivariate statistical techniques. Interesterified lipids were more spreadable and showed plastic behavior due to their lower consistency and solid fat contents. Decreases in melting points to a temperature range of 26.5-45.5 °C regardless of oil type were observed. Interesterified fats displayed mostly β’ and β’+β crystal forms. The CI of tallow did not result in the formation of significant amounts of trans-fatty acids. Samples interesterified with corn oil had lower free fatty acid contents (1.87-3.9%) and higher oxidation induction times (3.82-12.25h) than other lipids. Therefore, fats containing corn oil-tallow could be used in the baking industry due to their potentially good aeration properties and smooth texture.

Hydrate Phase Transition Kinetic Modeling for Nature and Industry–Where Are We and Where Do We Go?

Hydrate problems in industry have historically motivated modeling of hydrates and hydrate phase transition dynamics, and much knowledge has been gained during the last fifty years of research. The interest in natural gas hydrate as energy source is increasing rapidly. Parallel to this, there is also a high focus on fluxes of methane from the oceans. A limited portion of the fluxes of methane comes directly from natural gas hydrates but a much larger portion of the fluxes involves hydrate mounds as a dynamic seal that slows down leakage fluxes. In this work we review some of the historical trends in kinetic modeling of hydrate formation and discussion. We also discuss a possible future development over to classical thermodynamics and residual thermodynamics as a platform for all phases, including water phases. This opens up for consistent thermodynamics in which Gibbs free energy for all phases are comparable in terms of stability, and also consistent calculation of enthalpies and entropies. Examples are used to demonstrate various stability limits and how various routes to hydrate formation lead to different hydrates. A reworked Classical Nucleation Theory (CNT) is utilized to illustrate that nucleation of hydrate is, as expected from physics, a nano-scale process in time and space. Induction times, or time for onset of massive growth, on the other hand, are frequently delayed by hydrate film transport barriers that slow down contact between gas and liquid water. It is actually demonstrated that the reworked CNT model is able to predict experimental induction times.

Evaluation of Clove (Eugenia caryophyllata) and Tobacco (Nicotiana tabacum) powders for common carp Cyprinus carpio L. anesthesia

The anesthetic efficacy of two kinds of natural anesthetic Clove (Eugenia caryophyllatata) and Tobacco (Nicotiana tabacum) powders were evaluated on common carp (Cyprinus carpio L.) for handling and health management experiments. The concentrations of anesthetics were assessed by using two types of clove and tobacco anesthetics; each with three replicates for measuring induction times to anesthesia. Concentrations of 100, 200, 250, and 350 mg/l at the ratio 1:1 of the aqueous extract of both Clove (Eugenia caryophyllatata) and Tobacco (Nicotiana tabacum) to evaluate their effect on common carp anesthesia were used. The aqueous extract anesthetized fish partially in the high levels. No significant differences appeared on blood glucose, ALP, ALT and AST among different levels of the anesthesia concentrations used. As the anesthesia concentration increased, the Red blood cell (RBC) count and hemoglobin decreased.

FAST COMBUSTION MODES OF COMPOSITES “MOUND OF POROUS SILICON FRAGMENTS - SODIUM PERCHLORATE MONOHYDRATE” IN THE ATMOSPHERE

One of the criteria for the development of high-energy processes is the large specific surface area of the solid component of composites. Therefore, the maximum preservation of its nanostructured skeleton when separating the porous layer from the monocrystal substrate is relevant. Based on the analysis of the quality of the porous layer under various methods and modes of its formation, two methods were selected that provide simple and effective separation of the porous structure from the monocrystal. For composites based on mounds of porous silicon (pSi) fragments (MPSF), three series of experiments were carried out with fragments of porous layers of different age (formed within the previously established time limits before composites creation) with registration of combustion dynamics, temperatures and combustion spectra, as well as intensity of disturbances in the atmosphere forming during combustion of MPSF-composites. Four combustion modes of MPSF-composites were established: smoldering, frontal, aerosol, and frontal-aerosol. The ignition induction times were determined: from 1 to 50 ^s, pressure pulses in the atmosphere at a distance of 260 mm from the ignition site - up to 1.6 bar (with a mass of composites up to 0.4 g). Combustion velocities ofMPSF-composites and their dependences onthe coefficient of stoichiometry and humidity of sodium perchlorate monohydrate are established.

Unveiling the self-association and desolvation in crystal nucleation

As the first step in the crystallization process, nucleation has been studied by many researchers. In this work, phenacetin (PHEN) was selected as a model compound to investigate the relationship between the solvent and nucleation kinetics. Induction times at different supersaturation in six solvents were measured. FTIR and NMR spectroscopy were employed to explore the solvent–solute interactions and the self-association properties in solution. Density functional theory (DFT) was adopted to evaluate the strength of solute–solvent interactions and the molecular conformations in different solvents. Based on these spectroscopy data, molecular simulation and nucleation kinetic results, a comprehensive understanding of the relationship between molecular structure, crystal structure, solution chemistry and nucleation dynamics is discussed. Both the solute–solvent interaction strength and the supramolecular structure formed by the self-association of solute molecules affect the nucleation rate. The findings reported here shed new light on the molecular mechanism of nucleation in solution.