Anti‑algal activity of the 12‑5‑12 gemini surfactant results from its impact on the photosynthetic apparatus

A rapid amplification of algal population has a negative impact on the environment and the global economy. Thus, control of algal proliferation is an important issue and effective procedures which reduce algal blooms and control algal fouling are highly desired. Gemini surfactants are considered to have a low environmental impact, therefore they seem to be a promising group of detergents which could reduce algal blooms in water systems. Furthermore, due to their emulsifying properties they could replace algaecides added to antifouling paints and decrease algae adhesion to various surfaces. In this study the toxic effect of the 12-5-12 gemini surfactant was investigated on Chlorella cells and close attention was paid to a potential mechanism of its action. At the high cell density (10.05 × 107 cells/mL) a dose-dependent cell death was found and the IC50 value was reached at the concentration of 19.6 µmol/L after 72-h exposure to the surfactant. The decrease in chlorophyll autofluorescence shows that the photosynthetic apparatus seems to be the target of the tested compound. The presented studies indicate that gemini surfactants could effectively reduce algal blooms in water systems, and if added to paints, they could decrease algal growth on external building walls or other water immersed surfaces

Hand arm vibration, grip strength assessment and the prevalence of health disorders among stone crushing workers

This research was conducted to analyze the hand-arm vibration exposure levels in the workplace and the effects of vibrations on the health of stone crushing workers. The results suggested that the levels of vibration for rock drilling operators measured through two different types of systems were exceeding the Threshold Limit Values. Therefore a higher percentage of workers may be affected with hand-arm vibration syndrome. In addition the Hand Activity Level score was calculated with the support of a physician in order to analyze the occurrence of musculoskeletal disorders. Prolonged exposures to hand-arm vibration may also lead to loss of grip strength and proper functioning of hand. A digital hand dynamometer was used to calculate the grip strength of the workers using powered drill machine. A significant decrease of 5.86 kg of force in average grip strength of the workers was found before and after 1 h of drilling