Vacuum Infiltration of Polyamines Increases Firmness of Strawberry Slices Under Various Storage Conditions

Strawberry slices were vacuum infiltrated with polyamines and changes in firmness during storage were determined. Spermine and spermidine at 10 mM or 100 mM significantly increased firmness, whereas pu-trescine was not as effective at increasing firmness of slices stored at 1°C. The firming effect of the polyamines was similar to that of calcium chloride, and may have been due to their ability to bind to cell walls and membranes. In ripe receptacles of various cultivars which differed in firmness, putrescine (12–38 nmol/g fresh weight) and spermidine (19–33 nmoI/g fresh weight) were the predominant polyamines, while only low levels of spermine (<10 nmol/g fresh weight) were present. There was no discernible relationship between endogenous polyamine levels and fresh fruit firmness for the cultivars studied.     

Azides Part II — Mechanism of Fixation of Sulphonazido Dyes on Polyester Fibre*

Thermofixation of the reactive disperse azo dye, 2-hydroxy-5-methyl-4′-sulphonazidoazobenzene (I) containing a sulphonazido group, with polyester fibre leads to chemical bonding of the generated sulphonylnitrene with the fibre substrate. The nitrene interacts with the benzene ring of the polyester substrate through the formation of a sulphonamido link as well as through insertion followed by ring expansion of the adduct to yield the relevant N-sulphonyl-azepine. The mechanism is confirmed by means of a suitable model experiment of interaction of I with dimethyl terephthalate.     

Azides Part I - Reactive Dyes Containing the Azido Group for Synthetic-polymer Fibres*

Dyes containing sulphonylazido, carbonylazido, arylazido and azidoacetamido groups have been synthesized. These dyes react chemically with synthetic-polymer fibres, such as polyester, nylon and cellulose acetate. Their dyeing and fastness properties are discussed.     

Combustion synthesis of graphene and ultracapacitor performance

Graphene sheets are synthesized by a simple method starting from graphitic oxide as a precursor. Reaction of graphitic oxide at 250 °C with a combustion mixture of urea and ammonium nitrate results in the formation of thin graphene sheets. Graphene formation is characterized by XRD, TGA, XPS and TEM. Graphene materials synthesized by this method are investigated as an ultracapacitor material. Specific capacitance values of about 70 F/g are obtained at a current density of 100 mA/g by using KOH as an electrolyte.