Research on Electrospinning Process of Pullulan Nanofibers

A kind of pullulan biopolymer nanofibers with diameter of 100～700nm were obtained using redistilled water as solvent through electrospinning technology in this paper. The effects of the spinning solution concentration, applied voltage, flow rate and capillary–screen distance on morphology and diameter distribution of pullulan nanofiber were studied by SEM. The results show that, different parameters had great influence on nanofibers’ morphology and diameter. The optimal parameters of pullulan nanofibers electrospinning were: 22wt.% spinning solution concentration, 31 kV voltage, 20 cm capillary–screen distance and 0.5ml/h flow rate.

STUDIES IN THE SUPPOSED GOITROGENOUS EFFECT OF TAP WATER IN HELSINKI

ABSTRACT The study reported here was performed in order to examine the tap water of Helsinki for its alleged goitrogenous effect. In a short-term, 24-hour experiment with rats, kept on an iodine-poor diet, we noticed no inhibition of the 4-hour 131I uptake, as compared with that of animals receiving physiological saline instead of tap water. Two similar groups of rats receiving 1 and 2 mg of mercazole in redistilled water showed a distinct blockage of the 4-hour uptake, which proved the effect of this substance. In a long-term experiment of 5 weeks' duration there was no detectable difference in the body weight, thyroid weight and the 4-hour 131I uptake when the rats receiving tap water or distilled water to which 0.45 per cent of sodium chloride was added were compared with each other. Replacement of tap water by a 10 mg per cent solution of mercazole in redistilled water enlarged the thyroid to double its normal weight and increased the 131I uptake to approximately five times that of the controls. Thus our experiments failed to demonstrate any goitrogenous effect in the tap water of Helsinki. Changes similar to those produced by a long-term administration of mercazole, i. e. an enlargement of the thyroid and an increased thyroidal iodine uptake, have been shown to be due to milk collected from goitrous areas. The observations here reported confirm the importance of milk in the genesis of the goitre endemia of Helsinki. Attention is further called to the fact that a thyroidal enlargement combined with an increased thyroidal iodine uptake cannot always be taken as a sign of iodine deficiency because similar changes may be produced by the administration of goitrogens.