Work-rest pattern, alertness and performance assessment among naval personnel deployed at sea: A cross sectional study.

BACKGROUND: The combat naval vessels require continuous operational preparedness for guarding the vast coastline. Sailors onboard these ships are at risk for sleep deprivation. Sailors may be vulnerable to chronic fatigue; and decreased performance, vigilance, and cognitive functioning owing to sleep debt, which may affect safety during tactical operations and while transportation of ships. In this study we assessed the work-rest pattern and level of alertness during sailing and non sailing days. METHODS: Thirty-two male participants maintained a 24-h sleep and activity log for 5 days. Furthermore, qualitative gross motor activity was recorded using an actiwatch during these 5 days. Participants also completed four test sessions of personal digital assistant (PDA) based psychomotor vigilance task (PVT) test: pre-sleep, post-sleep, pre-work, and post-work. A comparison of data was performed using the Wilcoxon signed-rank test. RESULTS: Sailors received approximately 1 h less of rest while sailing. There was a significant difference in bedtime, wake-up time, total sleep time, sleep onset latency (SOL), wake up after sleep onset (WASO), and the number of awakenings during the non-sailing and the sailing days. PVT data showed significantly higher reaction times during the sailing days on pre-work and post-sleep sessions. CONCLUSION: Our study shows that although the sailors are not getting sufficient restorative sleep while sailing as compared to non-sailing days, this is not affecting their cognitive functioning while working.

Biosorption of arsenic (III) from aqueous solution by living cells of Bacillus cereus.

In this work, removal of arsenic (III) from aqueous solution by living cells (Bacillus cereus), biosorption mechanism, and characterization studies have been reported. B. cereus cell surface was characterized using SEM-EDX and FTIR. Dependence of biosorption on pH of the solution, biosorbent dose, initial arsenic (III) concentration, contact time, and temperature had been studied to achieve optimum condition. The maximum biosorption capacity of living cells of B. cereus for arsenic (III) was found to be 32.42 mg/g at pH 7.5, at optimum conditions of contact time of 30 min, biomass dosage of 6 g/L, and temperature of 30 ± 2 °C. Biosorption data of arsenic (III) are fitted to linearly transformed Langmuir isotherm with R (2) (correlation coefficient) >0.99. The pseudo-second-order model description of the kinetics of arsenic (III) is successfully applied to predict the rate constant of biosorption. Thermodynamic parameters reveal the endothermic, spontaneous, and feasible nature of sorption process of arsenic (III) onto B. cereus biomass. The arsenic (III) ions are desorbed from B. cereus using both 1 M HCl and 1 M HNO(3).