Chitosan as a growth stimulator in orchid tissue culture

The effect of shrimp and fungal chitosan on the growth and development of orchid plant meristemic tissue in culture was investigated in liquid and on solid medium. The growth of meristem explants into protocorm-like bodies in liquid medium was accelerated up to 15 times in the presence of chitosan oligomer, the optimal concentration being 15 ppm. The 1 kDa shrimp oligomer was slightly more effective compared to 10 kDa shrimp chitosan and four times more active compared to high molecular weight 100 kDa shrimp chitosan. The 10 kDa fungal chitosan was more effective compared with 1 kDa oligomer. The development of orchid protocorm into differentiated orchid tissue with primary shoots and roots was studied on solid agar medium. The optimal effect, the generation of 5–7 plantlets in 12 weeks was observed in the presence of 20 ppm using either 10 kDa fungal or 1 kDa oligomer shrimp chitosan. The data are consistent with preliminary results from field experiments and confirm unequivocally that a minor amount of chitosan has a profound effect on the growth and development of orchid plant tissue.     

New insulating particleboards prepared from mixture of solid wastes from tissue paper manufacturing and corn peel

New composite boards with low-thermal conductivity produced from a mixture of solid wastes from tissue paper manufacturing (solid waste TPM) and corn peel have been developed. The effects of solid waste TPM/corn peel ratio on the properties of the boards were investigated and the possibility of using recycled polystyrene packaging foam as a laminating agent to improve the quality of the boards was also evaluated. Our results show that the density of the particleboards decrease with increasing the amount of corn peel added in the mixture, leading to a decrease in thermal conductivity of the final product. In contrary, larger amount of solid waste TPM added in the mixture produced stronger boards. The lamination of recycled polystyrene on the surface of particleboards improves the mechanical properties and reduces the thickness swelling of the boards. The best improvement in mechanical properties and swelling resistance could be achieved when 15% polystyrene (w/v) was coated on the surface of the boards.     

Effects of oral contraceptive use on body mass index and blood pressure among female villagers in north-east Thailand

The use of contraceptives has become prevalent among females in Thailand in the past 20 years, and oral contraceptive use has been suggested to trigger changes in fat intake, energy expenditure, fat metabolism and blood pressure. Based on field investigations of 391 married women aged 20 years or over in Yasothon Province, North-east Thailand, this study aims to elucidate the effects of oral contraceptive use on body mass index (BMI: kg/m2) and blood pressure, taking into account reproductive histories and socioeconomic conditions. The proportion of obese (BMI > or = 25) subjects was high in the age groups 30-39, 40-49 and 50-59, accounting for, respectively, 39.4%, 51.1% and 48.5% of these populations. The proportion of women with hypertension (90/140 mmHg) was 23.7%, 18.5% and 26.2% in the 40-49, 50-59 and 60-69 age groups. Current contraceptive practices in the studied population included sterilization by operation, oral contraception and injection. These methods accounted for 43.0%, 12.8% and 8.2% of the population, respectively. Sociodemographic factors such as reproductive history, years of education and household income were not significantly related to BMI or to blood pressure (ANOVA with age adjustment). In contrast, oral contraceptive users had significantly higher BMIs and diastolic blood pressures (p<0.01, ANOVA with age adjustment). Multiple regression analysis also revealed that oral contraceptive use was a weak but significant contributing factor to both high BMI and blood pressure when sociodemographic factors were taken into account and controlled for statistically. It can thus be concluded that the use of contraceptive pills, which contain oestrogen and progestin and are provided free of charge to Thai women, tend to increase BMI and to elevate blood pressure.     

Continuously Distributed Glass Transition of Maca (Lepidium meyenii Walpers) Powder and Impact on Caking Properties

Food Biophysics - Water sorption isotherm, glass transition temperature (Tg), and caking properties of maca (Lepidium meyenii Walpers) powder were investigated. A broad endothermic shift reflecting...