Evaluation of adaptive low cost solar water pasteurization device for providing safe potable water in rural households.

This study was conducted to evaluate the effectiveness of a simplified, low cost, pasteurization device in inactivating the diarrheal pathogens present in pond/lake/river water in order to provide safe potable water to people living in the rural areas of low resource countries. In this process, water in polyethylene bags was exposed to sunshine, where UV radiation emissions and heat absorption from the sunshine occurs simultaneously, and maintaining the heating at <60 °C, and minimum UV radiation emissions of 996.2 W/m2 for approximately 30 minutes was found enough to inactivate diarrheal pathogens in water. The synergistic effect of heat, UV radiation emission and holding time causes the destruction of diarrheal pathogens. However, the performance of the device depends on the thickness of the insulation and the air gap between polyethylene bags. Regardless of sample sources, the highest population reduction of Escherichia coli observed in the bacterial challenge study was 6.8 ± 0.4 log CFU/ml. The physicochemical properties were found acceptable compared with USEPA potable water quality except turbidity, which is acceptable according to the BDS standard, and the shelf-life study results demonstrated that 6 months' storage of pasteurization device-treated water at room temperature is possible without compromising water quality. Therefore, this simplified pasteurization device could be useful in potable water-scarce areas of the world.

Noninvasive assessment of gastric acid secretion in man. Application of electrical impedance tomography (EIT).

Electrical impedance tomography (EIT) is a tubeless technique that generates tomographic images of gastric resistivity. We investigated the application of EIT to measure gastric acid secretion. Nineteen normal subjects underwent a standard intubation test. Basal acid output (BAO) and stimulated acid output (SAO) (millimoles per hour) were measured before and after pentagastrin, respectively. On a different day, EIT was performed before (basal) and after pentagastrin (stimulated). The changes in impedance over time were measured and the area under the curve (AUC) was calculated. Both the tests were repeated in 13 subjects after omeprazole treatment. As in the intubation test, there was the expected increase in AUC value after pentagastrin (basal vs stimulated; 1.2 +/- 2.8 vs 731 +/- 297, P < 0.0001). A significant fall in acid output and AUC following omeprazole pretreatment was observed (without vs with omeprazole; 20.5 +/- 5.7 vs 0.03 +/- 0.06, P < 0.0001 for intubation test and 731 +/- 297 vs 44 +/- 172, P < 0.0001 for EIT). There was a significant correlation between SAO and the delta AUC with (r = 0.65 P < 0.001) or without (r = 0.95, P < 0.001) omeprazole and in all the experiments (r = 0.87, P < 0.001). This study demonstrates the predictable change of gastric impedance and may be useful as a noninvasive test for measuring gastric acid secretion.