The use of chemicals is continuously growing both in total amount as well as in a number of different substances, among which organic chemicals play a major role. Owing to the growing public ...awareness on the need of protecting both ecosystems and human health from the risks related to chemical pollution, an increasing attention has been drowned to risk assessment and prioritization of organic pollutants. In this context, the aims of this study were (a) to perform an environmental risk assessment for 200 organic micropollutants including both regulated and emerging contaminants (pesticides, alkylphenols, pharmaceuticals, hormones, personal care products, perflourinated compounds and various industrial organic chemicals) monitored in four rivers located in the Mediterranean side of the Iberian Peninsula, namely, the Ebro, Llobregat, Júcar and Guadalquivir rivers; and (b) to prioritize them for each of the four river basins studied, taking into account their observed concentration levels together with their ecotoxicological potential. For this purpose, a prioritization approach has been developed and a resulting ranking index (RI) associated with each compound. Ranking index is based on the measured concentrations of the chemical in each river and its ecotoxicological potential (EC50 values for algae, Daphnia sp. and fish). Ten compounds were identified as most important for the studied rivers: pesticides chlorpyriphos, chlorfenvinphos, diazinon, dichlofenthion, prochloraz, ethion carbofuran and diuron and the industrial organic chemicals nonylphenol and octylphenol that result from the biodegration of polyethoxylated alkyphenol surfactants. Also, further research into chronic toxicity of emerging contaminants is advocated.
•Ranking index has been developed based on toxic units and detection frequency.•Two hundred micropollutants have been prioritized for Iberian rivers.•Pesticides and alkylphenols were identified as priority according to ranking index.•Emerging contaminants do not pose risk of acute effects in studied rivers.•Chronic toxicity research of emerging contaminants is proposed.
The relationship between processing, morphology, and properties of polymeric materials has been the subject of numerous studies of academic and industrial research. Finding an answer to this question ...might result in guidelines on how to design polymeric materials. Microfibrillar composites (MFCs) are an interesting class of polymer–polymer composites. The advantage of the MFC concept lies in developing in situ microfibrils by which a perfect homogeneous distribution of the reinforcement in the matrix can be achieved. Their potentially excellent mechanical properties are strongly dependent on the aspect ratio of the fibrils, which is developed through a three‐stage production process: melt blending, fibrillation, and isotropization. During melt blending, the polymers undergo different morphological changes, such as a breakup and coalescence of the droplets, which play a crucial role in defining the microstructure. During processing, various parameters may affect the morphology of the MFCs, which must be taken into account. Besides the processing parameters, the microstructure of the composite is dependent on the composition ratio of the blend and viscosity of the components, as well as the dispersion and distribution of the microfibrils. The objective here is to outline this importance and bring together an overview of the processing–structure–property relationship for MFCs.
Microfibrillar composites (MFCs) are considered as a promising group of environmentally friendly fiber composites, which might replace the commercial glass‐ and carbon‐fiber composites in the final applications. A comprehensive overview of the complex processing–structure–properties relationship for MFCs is presented. It is known that carefully developed microstructure is one of the most important requirements for achieving composites’ good mechanical properties.
The current state-of-the-art analysis techniques for petroleum fractions has progressed substantially during the past decade. This has helped to further improve the lumping procedures and modeling ...approaches of these complex systems. Recent advances in gas chromatography (GC), GC-field ionization mass spectrometry (GC-FIMS), and comprehensive gas chromatography (GC×GC) have made it possible to determine the compositions of fractions with up to 45 carbon atoms and in some cases up to C80. The combination of MS techniques with other selective detectors and reversed-phase column combinations has made it possible to quantify even traces of heteroatomic compounds in these complex hydrocarbon matrices. Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), in some cases combined with GC×GC for the lighter part, has pushed the characterization of larger macromolecules in particular asphaltenes. Matrix-assisted laser desorption/ionization (MALDI) is also used widely for this purpose but has the disadvantage that quantification is not obvious. The development of more detailed characterization techniques has not remained unnoticed in the petrochemical society and more recently in the petrochemical kinetic modeling society. More detailed characterization of petrochemical fractions has made the implementation of detailed kinetic models for simulation and optimization possible including more and more molecular detail. Additionally, advances in photoionization mass spectrometry (PI-MS) have allowed the detection of reactive intermediates and direct kinetic measurements in time-resolved experiments. It can only be expected that this trend will continue and that the application field will move from now primarily petrochemistry (from catalytic cracking, over hydrotreating, and hydrocracking to pyrolysis, combustion, and steam cracking) to larger-scale chemical recycling and biomass conversion processes.
Within this research the effect of injection molding temperature on polypropylene (PP)/poly(ethylene terephthalate) (PET) blends and microfibrillar composites was investigated. Injection molding ...blends (IMBs) and microfibrillar composites (MFCs) of PP/PET have been prepared in a weight ratio 70/30. The samples were processed at three different injection molding temperatures (
) (210, 230, 280 °C) and subjected to extensive characterization. The observations from the fracture surfaces of MFCs showed that PET fibers can be achieved by three step processing. The results indicated that
has a big influence on morphology of IMBs and MFCs. With increasing the
, distinctive variations in particle and fiber diameters were noticed. The differences in mechanical performances were obtained by flexural and impact tests. Establishing relationships between the processing parameters, properties, and morphology of composites is of key importance for the valorization of MFC polymers.
The treatment of infected wounds faces substantial challenges due to the high incidence and serious infection-related complications. Natural-based hydrogel dressings with favorable antibacterial ...properties and strong applicability are urgently needed. Herein, we developed a composite hydrogel by constructing multiple networks and loading ciprofloxacin for infected wound healing. The hydrogel was synthesized via a Schiff base reaction between carboxymethyl chitosan and oxidized sodium alginate, followed by the polymerization of the acrylamide monomer. The resultant hydrogel dressing possessed a good self-healing ability, considerable compression strength, and reliable compression fatigue resistance. In vitro assessment showed that the composite hydrogel effectively eliminated bacteria and exhibited an excellent biocompatibility. In a model of Staphylococcus aureus-infected full-thickness wounds, wound healing was significantly accelerated without scars through the composite hydrogel by reducing wound inflammation. Overall, this study opens up a new way for developing multifunctional hydrogel wound dressings to treat wound infections.
Three-dimensional (3D)-printed biodegradable polymer scaffolds are at the forefront of personalized constructs for bone tissue engineering. However, it remains challenging to create a biological ...microenvironment for bone growth. Herein, we developed a novel yet feasible approach to facilitate biomimetic mineralization via self-adaptive nanotopography, which overcomes difficulties in the surface biofunctionalization of 3D-printed polycaprolactone (PCL) scaffolds. The building blocks of self-adaptive nanotopography were PCL lamellae that formed on the 3D-printed PCL scaffold via surface-directed epitaxial crystallization and acted as a linker to nucleate and generate hydroxyapatite crystals. Accordingly, a uniform and robust mineralized layer was immobilized throughout the scaffolds, which strongly bound to the strands and had no effect on the mechanical properties of the scaffolds. In vitro cell culture experiments revealed that the resulting scaffold was biocompatible and enhanced the proliferation and osteogenic differentiation of mouse embryolous osteoblast cells. Furthermore, we demonstrated that the resulting scaffold showed a strong capability to accelerate in vivo bone regeneration using a rabbit bone defect model. This study provides valuable opportunities to enhance the application of 3D-printed scaffolds in bone repair, paving the way for translation to other orthopedic implants.
The main goal of this research is to study the development of crystalline morphology and compare it to various mechanical properties of microfibrillar composites (MFCs) based on polypropylene (PP) ...and poly(ethylene terephthalate) (PET), by adding a functional compatibilizer and a non-functional rubber in two different steps in the processing sequence. The MFCs were prepared at a weight ratio of 80/20 PP/PET by twin screw extrusion followed by cold drawing and injection moulding. The non-functionalized polyolefin-based elastomer (POE) and the functional compatibilizer (i.e., POE grafted with maleic anhydride (POE-
-MA)) were added in a fixed weight percentage at two stages: during extrusion or during injection moulding. The morphology observations showed differences in crystalline structure, and the PP spherulite size was reduced in all MFCs due to the presence of PET fibrils. Their relationship with the mechanical performances of the composite was studied by tensile and impact tests. Adding the functional compatibilizer during extrusions showed better mechanical properties compared to MFCs. Overall, a clear relationship was identified between processing, structure and properties.
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•Pyrolysis of virgin and LDPE and PP wastes was performed in a pilot setup.•GC × GC was applied to identify and quantify the composition of the pyrolysis oils.•Identification of ...optimal temperature and pressure for pyrolysis.•The formation of preferentially propylene oligomers during PP pyrolysis.•Plastic contaminations such as PVC and biomass intensify the coke formation.
Due to the complexity and diversity of polyolefinic plastic waste streams and the inherent non-selective nature of the pyrolysis chemistry, the chemical decomposition of plastic waste is still not fully understood. Accurate data of feedstock and products that also consider impurities is, in this context, quite scarce. Therefore this work focuses on the thermochemical recycling via pyrolysis of different virgin and contaminated waste-derived polyolefin feedstocks (i.e., low-density polyethylene (LDPE), polypropylene (PP) as main components), along with an investigation of the decomposition mechanisms based on the detailed composition of the pyrolysis oils. Crucial in this work is the detailed chemical analysis of the resulting pyrolysis oils by comprehensive two-dimensional gas chromatography (GC × GC) and ICP-OES, among others. Different feedstocks were pyrolyzed at a temperature range of 430–490 °C and at pressures between 0.1 and 2 bar in a continuous pilot-scale pyrolysis unit. At the lowest pressure, the pyrolysis oil yield of the studied polyolefins reached up to 95 wt%. The pyrolysis oil consists of primarily α-olefins (37–42 %) and n-paraffins (32–35 %) for LDPE pyrolysis, while isoolefins (mostly C9 and C15) and diolefins accounted for 84–91 % of the PP-based pyrolysis oils. The post-consumer waste feedstocks led to significantly less pyrolysis oil yields and more char formation compared to their virgin equivalents. It was found that plastic aging, polyvinyl chloride (PVC) (3 wt%), and metal contamination were the main causes of char formation during the pyrolysis of polyolefin waste (4.9 wt%).
Several mixed recycled plastics, namely, mixed bilayer polypropylene/poly (ethylene terephthalate) (PP/PET) film, mixed polyolefins (MPO) and talc-filled PP were selected for this study and used as ...matrices for the preparation of microfibrillar composites (MFCs) with PET as reinforcement fibres. MFCs with recycled matrices were successfully prepared by a three-step processing (extrusion—cold drawing—injection moulding), although significant difficulties in processing were observed. Contrary to previous results with virgin PP, no outstanding mechanical properties were achieved; they showed little or almost no improvement compared to the properties of unreinforced recycled plastics. SEM characterisation showed a high level of PET fibre coalescence present in the MFC made from recycled PP/PET film, while in the other MFCs, a large heterogeneity of the microstructure was identified. Despite these disappointing results, the MFC concept remains an interesting approach for the upcycling of mixed polymer waste. However, the current study shows that the approach requires further in-depth investigations which consider various factors such as viscosity, heterogeneity, the presence of different additives and levels of degradation.
Acinetobacter baumannii
is an emerging nosocomial pathogen resistant to a wide spectrum of antibiotics, with great potential to form a biofilm, which further aggravates treatment of infections caused ...by it. Therefore, searching for new potent agents that are efficient against
A. baumannii
seems to be a necessity. One of them, which has already been proven to possess a wide spectrum of biological activities, including antimicrobial effect, is cinnamon essential oil. Still, further increase of antibacterial efficacy and improvement of bioavailability of cinnamon oil is possible by emulsification process. The aim of this study was comparative analysis of cinnamon essential oil and its emulsion against biofilm forming
A. baumannii
clinical isolates. Furthermore, the investigation of toxicological aspects of possible applications of essential oil and emulsion was done as well. Gas chromatography–mass spectrometry of essential oil indicated
trans
-cinnamaldehyde as the most abundant component. The cinnamon emulsion was synthesized from cinnamon essential oil by combining modified low- and high- energy methods. Synthesized emulsion was characterized with Fourier-transform infrared spectroscopy and photon correlation spectroscopy. Both substances exhibited significant antibacterial (minimal inhibitory concentrations in the range 0.125–0.5 mg/ml) and antibiofilm effects (inhibitions of formation and reduction of pre-formed biofilm were 47–81 and 30–62%, respectively). Compared to essential oil, the efficacy of emulsion was even stronger considering the small share of pure oil (20%) in the emulsion. The result of biofilm eradication assay was confirmed by scanning electron microscopy. Even though the cytotoxicity was high especially for the emulsion, genotoxicity was not determined. In conclusion, strong antibacterial/antibiofilm effect against
A. baumannii
of the cinnamon essential oil and the fact that emulsification even potentiated the activity, seems to be of great significance. Observed cytotoxicity implicated that further analysis is needed in order to clearly determine active principles being responsible for obtained antibacterial/antibiofilm and cytotoxic properties.
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