Zinc increases flame retardancy of PVC
PVC is used in a myriad of roles from electrical equipment to packaging and protective clothing. It is usually relatively non-flammable but plasticisers are commonly added to increase its flexibility although this also increases its flammability. To counter this, aluminium hydroxide is added, but this can lead to processing problems and deterioration in mechanical and electrical properties.

Scientist at the University of Hebei, China, have now developed PVC with improved flame-retardant properties. They found that the addition of a small amount of zinc oxide reacted synergistically with the aluminium hydroxide, increasing its flame-retardant properties and decreasing the amount of aluminium hydroxide required.

Thermal behavior and flame retardancy of flexible poly(vinyl chloride) treated with Al(OH)3 and ZnO, Hongqiang Qu, Weihong Wu, Yunhong Jiao, Jianzhong Xu, Polymer International, DOI: 10.1002/pi.1870 (Available on EarlyView)

Multiple factors cause insecticide resistance
Researchers working in the US and China have discovered the mechanisms that confer insecticide resistance on mosquitoes.

The group found that resistance to pyrethroid insecticides could be conferred by multiple routes. These included a mutation in a sodium channel and three different classes of enzyme were also implicated in conferring resistance.

The mosquito Culex quinquefasciatus is found throughout the wet tropics and is a carrier of West Nile virus and Saint Louis encephalitis virus and is now resistant to many insecticides.

They hope that increased understanding of how mosquitoes protect themselves will lead to the development of new strategies to tackle the pest.

Resistance in the mosquito, Culex quinquefasciatus, and possible mechanisms for resistance, Qiang Xu, Huqi Liu, Lee Zhang, Nannan Liu, Pest Management Science, DOI: 10.1002/ps.1090 (Available on EarlyView)

Avoiding allergens
Allergens are a serious problem for a substantial portion of the population, causing potentially life-threatening conditions such as anaphylactic shock and asthma.

A research group working in India and the UK have developed a biosensor that they hope will help allergen-sensitive individuals. The biosensor uses an enzyme which degrades a specific protein-based allergen creating amino acids. These are then degraded to hydrogen peroxide by another enzyme which can be detected to give an approximate idea of the level of allergens present. The researchers think that this could help people avoid highly allergenic environments.

Screen-printed biosensor for allergens, P Sarkar, D Ghosh, D Bhattacharya, R Kataky, SJ Setford, SF White, APF Turner, Journal of Chemical Technology and Biotechnology, DOI: 10.1002/jctb.1340 (Available on EarlyView)

Natural mash is best
Researchers at the Institu del Frío-CSIC in Spain have examined the quality of frozen, freshly made and commercially-produced mashed potato. Fresh mash was made from Kennebec potatoes with commercial mash produced from potato flakes. The mash was then frozen for one day, three months or 12 months.

The quality of commercially produced mash deteriorated substantially as a result of freezing due to starch clumping. The naturally-produced mash fared much better with a lower decrease in quality. The taste was unaffected by the length of storage.

Effect of freezing/thawing conditions and long-term frozen storage on the quality of mashed potatoes, M Dolores Álvarez, Cristina Fernández, Wenceslao Canet, Journal of the Science of Food and Agriculture, DOI: 10.1002/jsfa.2264 (Available on EarlyView)