Green chemical method could be a promising route to achieve large scale synthesis of nanostructures for biomedical applications. Here, we describe a green chemical synthesis of silver nanoparticles (Ag NPs) on chitosan-based electrospun nanofibers using Eucalyptus leaf extract. A series of silver salt (AgNO 3 ) amounts were added to a certain composition of chitosan/polyethylene oxide aqueous acetic acid solution. The solutions were then electrospun to obtain nanofibrous mats and then, morphology and size of nanofibers were analyzed by scanning electron microscopy (SEM). Incubation of AgNO 3 -containing mats into Eucalyptus leaf extract led to the formation of Ag NP clusters with average diameter of 91 6 24 nm, depicted by SEM and transmission electron microscopy. Surface enhanced Raman spectroscopy also confirmed formation of Ag NPs on the nanofibers. The mats also showed antimicrobial activity against Escherichia coli and Staphylococcus aureus bacteria with bigger inhibition zone for extract-exposed mats against S. aureus.

The ventilation heat loss in a typical unimproved UK dwelling is approximately equal to the conduction loss; therefore draught-proofing measures should form part of any energy refurbishment package. This will improve the building's air permeability but risks incurring additional energy costs associated with the need to provide controlled ventilation to maintain indoor air quality. This paper aims to determine the point at which the air permeability of the building improves the energy performance by enough to justify the increase in energy associated with the installation of mechanical ventilation with heat recovery (MVHR). A 1930's style semi-detached house, representative of a large proportion of solid wall dwellings in the UK, has been improved by a package of measures including MVHR. The building air tightness plays a critical role in reducing the building energy consumption and CO 2 emissions.

A low cost colorimetric microfluidic paper-based analytical device (µPAD) for the determination of nitrite in real samples with improved precision has been fabricated and its performance has been evaluated. The µPAD was fabricated by laser cutting and patterning on the paper and the nitrite concentration measurement is based on the modified Griess assay. In this assay, tartaric acid was used as an antioxidant reagent to increase Griess reagent stability. A novel geometrical design was used to achieve better color gradient over µPAD detection zone for improving the precision of the measurements. The results of measurement indicate that the fabricated device could successfully detect and quantify the nitrite concentration in real samples with the limit of detection of 15 μM. The results are in good accordance with the results of spectrophotometry. The fabricated sensor has the potential to be applied for monitoring of the trace level of nitrite in drinking water and environmental applications.