Polystyrene, despite its high flammability, is widely used as a thermal insulation material for buildings, for food packaging, in electrical and automotive industries, etc. A number of modification routes have been explored to improve the fire retardance and boost the thermal stability of commercially important styrene-based polymeric products. The earlier strategies mostly involved the use of halogenated fire retardants. Nowadays, these compounds are considered to be persistent pollutants that are hazardous to public and environmental health. Many well-known halogen-based fire retardants, regardless of their chemical structures and modes of action, have been withdrawn from built environments in the European Union, USA, and Canada. This had triggered a growing research interest in, and an industrial demand for, halogen-free alternatives, which not only will reduce the flammability but also address toxicity and bioaccumulation issues. Among the possible options, phosphorus-containing compounds have received greater attention due to their excellent fire-retarding efficiencies and environmentally friendly attributes. Numerous reports were also published on reactive and additive modifications of polystyrene in different forms, particularly in the last decade; hence, the current article aims to provide a critical review of these publications. The authors mainly intend to focus on the chemistries of phosphorous compounds, with the P atom being in different chemical environments, used either as reactive, or additive, fire retardants in styrene-based materials. The chemical pathways and possible mechanisms behind the fire retardance are discussed in this review.
The present work focuses on the development of functional polyurethane hybrids through the incorporation of surface modified TiO 2 nanoparticles. For improving the nanoparticle dispersion and increasing possible interactions between nano-particles and polyurethane matrix, the surface of the nano-particles was modified with 1,3,5-triazine core silane coupling agent. The surface modification of nanoparticles was confirmed by FESEM, FT-IR and Raman spectroscopic techniques. The functionalized nanoparticles were then inscribed in 0, 1 and 2 weight percentages into polyurethane matrix. The as prepared composite coatings were investigated for various anti-microbial, thermo-mechanical and anticorrosive properties. The tensile strength of polyurethane was improved by 300 % upon addition of 2 wt% of modified TiO 2 nanoparticles as compared to neat polyurethane. Fog test and electrochemical polarization studies suggest that the corrosion resistance increases with increase of the modified TiO 2 content in the coating formulation. The composite coatings also have good resistance towards various bacterial and fungal stains as compared to the pure polyurethanes. The coatings substantially gain hydrophilic nature symbiotically with TiO 2 content suggesting its potential application as self-cleanable material.
Tomato (Lycopersicon esculentum L.) is one of the most widely grown crops in the world. This crop is easily prone to various diseases. One such disease is late blight, caused by the fungus Phytophthora infestans. The first symptoms of late blight on tomato leaves are irregularly shaped, water soaked lesions, which are typically found on the younger leaves of the plant canopy. During humid conditions, white cottony growth may be visible on the underside of affected leaves. As the disease progresses, lesions enlarge causing leaves to brown, shrivel and perish. Hence in the present paper, a novel computer vision system has been proposed for detection and analysis of late blight disease. The proposed system implements thresholding algorithm to classify the leaf as diseased or healthy. Later it uses K-means clustering algorithm for analyzing late blight disease. The experiment was carried out on leaves of tomato collected from various plantations. The accuracy, sensitivity and specificity of the developed system in analyzing the late blight disease are 84%, 85% and 80% respectively.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.