Salting-out assisted liquid–liquid extraction with dansyl chloride for the determination of biogenic amines in food

Biogenic amines (BAs) are compounds present in foodstuff of animal origin that not only can be harmful to the consumer but can also serve as indicators of the product's edibility status. However, BAs’ analysis is rather complicated. Derivatisation methods have been employed to make their analysis less challenging. Salting-out assisted liquid–liquid extraction (SALLE) was herein applied to decrease time that the derivatising agent dansyl chloride (DNS-Cl) requires to be effective. DNS-Cl derivates were separated and analysed by high-performance liquid chromatography with UV and fluorescence detection (HPLC-UV/FD). It was by this way possible to analyse methylamine, dimethylamine, ethylamine, β-phenylethylamine, isopentylamine, putrescine, cadaverine, histamine, tyramine, spermidine and spermine in a straightforward manner in several fish-based and meat-based samples, obtaining results in the order of magnitude of about a few mg per kg. All calibrations curves had r² higher than 0.99, and limits of detection ranged from 0.0075 to 1.6 mg L⁻¹.     

Characterization of expanded polystyrene and its composites by supercritical carbon dioxide foaming approach

Journal of Porous Materials - Supercritical carbon dioxide (scCO2) has been used as a physical blowing agent to produce polymer expanded materials. Firstly, a statistic study was performed to...     

Correction to: Corrosion of Metallic and Structural Elements Exposed to Acid Mine Drainage (AMD)

Mine Water and the Environment -     

Health risk assessment of volatile organic compounds at daycare facilities

Children are particularly vulnerable to many classes of the volatile organic compounds (VOCs) detected in indoor environments. The negative health impacts associated with chronic and acute exposures of the VOCs might lead to health issues such as genetic damage, cancer, and disorder of nervous systems. In this study, 40 VOCs including aldehydes and ketones, aliphatic hydrocarbons, esters, aromatic hydrocarbons, cyclic terpenes, alcohols, and glycol ethers were identified and qualified in different locations at the University of Missouri (MU) Child Development Laboratory (CDL) in Columbia, Missouri. Our results suggested that the concentrations of the VOCs varied significantly among classrooms, hallways, and playground. The VOCs emitted from personal care and cleaning products had the highest indoor levels (2-ethylhexanol-1, 3-carene, homomenthyl salicylate with mean concentration of 5.15 µg/m³, 1.57 µg/m³, and 1.47 µg/m³, respectively). A cancer risk assessment was conducted, and none of the 95th percentile dose estimates exceeded the age-specific no significant risk levels (NSRL) in all classrooms. Dimensionless toxicity index scores were calculated for all VOCs using a novel web-based framework called Toxicological Prioritization Index (ToxPi), which integrates multiple sources of toxicity data. According to the method, homomenthyl salicylate, benzothiazole, 2-ethylhexyl salicylate, hexadecane, and tridecane exhibited diverse toxicity profiles and ranked as the five most toxic indoor VOCs. The findings of this study provide critical information for policy makers and early education professionals to mitigate the potentially negative health impacts of indoor VOCs in the childcare facilities.     

Ascorbic Acid Supplementation Improves Skeletal Muscle Growth in Pacu (Piaractus mesopotamicus) Juveniles: In Vivo and In Vitro Studies

In fish, fasting leads to loss of muscle mass. This condition triggers oxidative stress, and therefore, antioxidants can be an alternative to muscle recovery. We investigated the effects of antioxidant ascorbic acid (AA) on the morphology, antioxidant enzyme activity, and gene expression in the skeletal muscle of pacu (Piaractus mesopotamicus) following fasting, using in vitro and in vivo strategies. Isolated muscle cells of the pacu were subjected to 72 h of nutrient restriction, followed by 24 h of incubation with nutrients or nutrients and AA (200 µM). Fish were fasted for 15 days, followed by 6 h and 15 and 30 days of refeeding with 100, 200, and 400 mg/kg of AA supplementation. AA addition increased cell diameter and the expression of anabolic and cell proliferation genes in vitro. In vivo, 400 mg/kg of AA increased anabolic and proliferative genes expression at 6 h of refeeding, the fiber diameter and the expression of genes related to cell proliferation at 15 days, and the expression of catabolic and oxidative metabolism genes at 30 days. Catalase activity remained low in the higher supplementation group. In conclusion, AA directly affected the isolated muscle cells, and the higher AA supplementation positively influenced muscle growth after fasting.     

Biodegradable PLA based nanocomposites for packaging applications: The effects of organo-modified bentonite concentration

The effects of concentration and surface modification of two Brazilian bentonite clays on nanocomposites' properties based on polylactic acid – (PLA) were investigated. The samples were prepared by the extrusion/injection method to obtain biodegradable packaging plastics. The raw materials and their bionanocomposites were characterized by various techniques. Natural clay samples presented a size of around 2 μm while the modified ones' size was 5–6 μm, probably due to the presence of cetyltrimethylammonium bromide in the interlayer space. The particle size and the contact angle increased with the treatment and the clay's density decreased. The organoclays were homogeneously dispersed in PLA, which can be associated with the interactions between PLA chains' carbonyl groups and the organoclays. The bionanocomposites present modified clay particles axis aligned to the flow direction of the extruder/injector. Chocolate organoclay acts as a nucleating agent to PLA crystal growth, increasing the sample's crystallinity, while Bofe organoclay interferes with the amorphous chain's mobility and diminishes the sample's crystallization. The addition of both organoclays to PLA diminished the sample's elongation at break and strength, although the organoclays increased the sample's Young modulus, even though Bofe organoclay is more active in PLA amorphous phase and Chocolate organoclay on the crystalline one.     

Hybrid‐permeability model evaluation through concepts of tortuosity and resistance rate: Properties of manufactured hybrid laminate

The mechanical properties of composite structures depend on the preform impregnation and a successful impregnation can be achieved using the permeability relation in the case of an infusion process. The objective of this study is to develop an analytical model to predict the permeability K of carbon and glass fabrics through hybrid laminate using different stacking sequence, applying an average‐permeability model. Preforms permeabilities were evaluated through tortuosity and void‐volume fraction. The model allows the analysis of different stacking sequence combinations (interleaved and in block), measuring the contribution of each material type. As a result, hybrid average‐permeability model was validated through experimental permeability tests, dimensionless permeability, and tortuosity results, besides enabling predictions of the flow front behavior with <10% of deviation. Carbon fiber preforms exhibited higher flow resistance, which is explained via tortuosity concept. A combination of carbon/glass preforms presented an increased permeability, which means a synergy that provides higher value of K. In addition, the use of hybrid preforms, especially Hybrid 2 stacking sequence, reduce the injection time and void formation, ensuring composite impregnation quality. POLYM. ENG. SCI., 59:1215–1222 2019. © 2019 Society of Plastics Engineers