Pretreating Recycled Carbon Fiber Nonwoven with a Sizing Formulation to Improve the Performance of Thermoplastic Recycled Fiber-Reinforced Composites

Pyrolysis is already an established recycling method to recover the carbon fibers of end-of-life composites. However, the pyrolysis process removes the fiber sizing. Fiber sizing is a critical step in composite material production, influencing adhesion, protection and overall performance. In this study, recycled carbon nonwoven reinforcements made from pyrolyzed carbon fibers were pretreated to improve the mechanical properties of polyamide and polypropylene composites. The pretreatment involved applying specific coatings (sizings) on the nonwoven by spraying. Pretreated and non-pretreated composites were prepared by compression molding to investigate the impact of the fiber pretreatment on the tensile properties and interlaminar shear strength. The tests were performed in the 0° and 90° directions of the composite plate. The results revealed that pretreatment had little effect on the polyamide composites. However, significant improvements were obtained for the polypropylene composites, as an increase of more than 50% in tensile strength was achieved in the 0° direction and more than 35% in the 90° direction. In addition, the interlaminar shear strength increased from 11.9 MPa to 14.3 MPa in the 0° direction and from 14.9 MPa to 17.8 MPa in the 90° direction

Novel strategies for rapid trace element analysis of polyamide by graphite furnace atomic absorption spectrometry and inductively coupled plasma mass spectrometry : dissolution in an organic solvent versus direct solid sampling approaches

Titanium dioxide is added to polyamide since it efficiently scatters visible light and imparts whiteness, brightness and high opacity. TiO2, however, can degrade easily and to counteract this, it is coated with a layer of inorganic material, containing Al, Mn and Si. For quality control, it is important to develop fast and reliable methods for the determination of these elements. Due to the fact that acid digestion techniques are labor-intensive, time-consuming and bring about the risk of contamination, an alternative dissolution procedure has been developed using formic acid to dissolve polyamide. The solutions thus obtained were measured by means of graphite furnace atomic absorption spectrometry (GFAAS) and inductively coupled plasma mass spectrometry (ICPMS). For the latter technique, sample introduction was performed using a pneumatic nebulization system, containing a membrane desolvating unit to remove the organic solvent. This approach provided satisfactory results in terms of precision (6-10% RSD) and limits of detection (0.1-0.6 mu g g(-1), except for Si when using ICPMS). Addition of formic acid to the calibration standards was demonstrated to be required. To enhance the sensitivity, increase the sample throughput and reduce the risk of contamination and/or analyte losses, the direct solid sampling methods solid sampling GFAAS and electrothermal vaporization (ETV)-ICPMS were also evaluated. Both techniques provided accurate results using calibration versus aqueous standards, with RSD values of similar to 10%. Limits of detection were improved considerably compared to those attainable after dissolution. In contrast to GFAAS, ETV-ICPMS allows the simultaneous determination of all of the analytes

Mass discrimination in dynamic reaction cell (DRC)-ICP-mass spectrometry

The possibility of overcoming spectral interferences by means of selective ion-molecule chemistry in a dynamic reaction cell (DRC) leads to an extension of the application range of ICP-MS for isotopic analysis. In this work, the effect of various instrumental parameters and the matrix composition on the mass discrimination (defined as the deviation between the experimental result and the corresponding 'true' isotopic ratio) was systematically studied. It is demonstrated that various DRC parameters-collision gas flow rate, reaction gas flow rate and bandpass settings-affect the mass discrimination. This observation is probably to be attributed to in-cell fractionation effects, occurring as a result of collisional losses, space-charge effects and kinetic effects in the ion-molecule chemistry. As the isotopic standard and the sample are always measured under identical conditions, external correction for mass discrimination assures accurate results. Under all conditions tested, internal correction for mass discrimination on the other hand-a strategy often used in Sr isotopic analysis did not provide accurate results. Also the matrix composition is demonstrated to have a significant influence on the mass discrimination, especially when using condensation product ions for isotope ratio measurement. This disadvantage can be overcome by using a matrix-matched isotopic standard for external correction or by isolation of the target element from the concomitant matrix, or at least its separation from the dominant matrix components

White Paper: Bridging the gap between surveillance data and antimicrobial stewardship in the animal sector-practical guidance from the JPIAMR ARCH and COMBACTE-MAGNET EPI-Net networks

BACKGROUND: The JPIAMR ARCH and COMBACTE-MAGNET EPI-Net networks have joined efforts to formulate a set of target actions to link the surveillance of antimicrobial usage (AMU) and antimicrobial resistance (AMR) with antimicrobial stewardship (AMS) activities in four different settings. This White Paper focuses on the veterinary setting and embraces the One Health approach.METHODS: A review of the literature was carried out addressing research questions in three areas: AMS leadership and accountability; AMU surveillance and AMS; and AMR surveillance and AMS. Consensus on target actions was reached through a RAND-modified Delphi process involving over 40 experts in infectious diseases, clinical microbiology, AMS, veterinary medicine and public health, from 18 countries.RESULTS/DISCUSSION: Forty-six target actions were developed and qualified as essential or desirable. Essential actions included the setup of AMS teams in all veterinary settings, building government-supported AMS programmes and following specific requirements on the production, collection and communication of AMU and AMR data. Activities of AMS teams should be tailored to the local situation and capacities, and be linked to local or national surveillance systems and infection control programmes. Several research priorities were also identified, such as the need to develop more clinical breakpoints in veterinary medicine.CONCLUSIONS: This White Paper offers a practical tool to veterinary practitioners and policy makers to improve AMS in the One Health approach, thanks to surveillance data generated in the veterinary setting. This work may also be useful to medical doctors wishing to better understand the specificities of the veterinary setting and facilitate cross-sectoral collaborations