Evaluation of charge density and the theory for calculating membrane potential for a nano-composite nylon-6,6 nickel phosphate membrane.

A new crystalline organic-inorganic nano-composite nylon-6,6 nickel phosphate membrane was synthesised subsequent to which (a) the physico-chemical characteristics of the membrane were evaluated employing FTIR, SEM, EDX, TEM, XRD and porosity measurements, and (b) membrane potential measurements were conducted employing different concentrations (0.0001 ≤c (M) ≤ 1) of KCl, NaCl and LiCl 1:1 electrolyte solutions. The Teorell, Meyer and Sievers (TMS) theoretical method was employed for evaluating the charge density of the synthesised membranes, and the observed data were utilised to calculate membrane potentials using the extended TMS theory. Charge density for 1:1 electrolyte solutions was found to decrease in the order KCl > NaCl > LiCl, which is in accordance with a decrease in the size of the cation. The synthesised membrane was found to be cation-selective with the measured membrane potentials found to be positive in all instances, decreasing in the order LiCl > NaCl > KCl, which is in accordance with an increase in the size of the cation for the chosen electrolytes. Observed potential data were used to calculate the transference numbers, mobilities, distribution coefficients, and charge effectiveness of ions and the theoretically calculated potential values were found to be in good agreement with the experimentally observed values.

[The reliability of prenatal echographic studies of neural tube defects; a prospective study]. / De betrouwbaarheid van antenatale echografische diagnostiek van neurale-buisdefecten; een prospectief onderzoek.

OBJECTIVE: To determine the accuracy of antenatal ultrasound investigation in the detection of neural tube defects. DESIGN: Prospective study. SETTING: University Hospital Utrecht. METHOD: Specific ultrasound investigation was carried out in 739 patients at risk for carrying a fetus with a neural tube defect. RESULTS: The sensitivity of ultrasound investigation was 91.7%, the specificity 99.8%, the positive predictive value 84.6% and the negative predictive value 99.9%. CONCLUSION: In our view expert ultrasonographic examination with appropriate counselling is an acceptable alternative for patients with a moderately increased risk of having a foetus with NTD and sufficiently accurate to replace invasive diagnostic procedures.