1,720,975 research outputs found
Kinetic study of the polycondensation of acetone to produce isophorone adopting alumina and magnesia as catalysts
No full textKinetic study of the effect of catalyst in the polycondensation of lactic acid to produce low molecular weight polymers
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AI-based Quantification of Volatile Organic Compounds in Gas Mixtures Exploiting Temperature Modulation of MOS Sensor Array
No full textThe analysis of biological fluids, particularly exhaled breath (EB), offers a promising noninvasive approach for early disease diagnosis by detecting volatile organic compounds (VOCs). Traditional techniques like gas chromatography-mass spectrometry (GC-MS), while sensitive, are limited by high costs and complexity. This study explores the application of temperature modulation (TM) to enhance the performance of metal oxide semiconductor (MOS) sensors in identifying and quantifying VOCs in complex mixtures. Using a custom-built electronic nose (eNose) system equipped with four MOS gas sensors and a square-triangular TM pattern, mixtures of three VOCs, namely acetone, isopropanol, and toluene, were analyzed across three concentration ranges. Sensible parameters extracted from each sensor response were used to discriminate VOCs and concentrations by random forest (RF) classifier achieving an accuracy of 91%, precision of 91%, recall of 89%, and F1 -score of 89% in classifying the mixtures. Feature re-mapping coupled with a CatBoost classifier leveraging individual VOC analysis reduced the experimental burden and achieved an 84% classification accuracy. These findings demonstrate that TM combined with artificial intelligence (AI) can address key challenges in complex gas mixture analysis, advancing the potential of portable eNose systems for clinical diagnostics
Emissions of hazardous compounds during PVC manufacturing processes
No full textRaw plastic materials used in the plastic manufacturing industries are pellets, powder or sheet mixtures constituted by the main polymer together with several additives (e.g., plasticizers, stabilizers, antioxidants, pigments). The manufacturing processes themselves depend on both the polymer characteristics and the artifact characteristics. During the plastic manufacturing, toxic products can enter the working environment due to the plastic heating. A complete environmental analysis looking for all the pollutants that can be foreseen is usually carried out to define if the workers' risk level is acceptable or not. Therefore, a simple and cheap screening procedure has been developed and validated by comparison with environmental analysis carried out in two PVC manufacturing industries. Such a procedure can give information on which toxic products are expected to enter the working environment as well as on the relative amount of such products, and it can be used to screen which situations deserve a deeper environmental analysis. For this reason, a preliminary study aimed to evaluate the release of toxic compounds in manufactures of extruded cables has been carried out. Main aim of the work was to identify and quantify the possible emissions released by several PVC-based materials once they undergo heating treatments; typical operating conditions that are used during cable production have been reproduced in a laboratory-scale apparatus and different analytical techniques have been applied in order to detect the emissions. In particular, the attention has been focused on the determination of volatile organic compounds (VOCs) and aldehydes. During the experiments, plastic samples were rapidly exposed to an hot environment, kept in isothermal condition, at different temperatures depending on the type of material and the duration of the reference industrial activity
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