Null water

Mason, P. E., S. Ansell, and G. W. Neilson, Neutron diffraction studies of electrolytes in null water a direct determination of the first hydration zone of ions/. Phys. Condens. Matter, 2006.18 8437-8447. 

In this article, we present a brief outline of the methods used and introduce the structural properties which can be calculated directly from the experimental data. Several examples have been selected to demonstrate the power of these methods, with reference to studies of monatomic ions such as Ni + and Cl (Figs. 1-3). We also mention an extension to the NDIS method that applies to aqueous solutions of null water and enables one to determine the nearest neighbour coordination of strong cations for cations which do not possess isotopes suitable for the NDIS method. ... 

Once the limits of the NDIS methods had been established, the structures around many other cations and anions were eventually obtained, and today there exists a substantial body of information of the structure of many cations. Most recently this information has been augmented with the developed technique of working with salts in solutions of null water — a mixture of 63.7% H2O and 36.3% D2O which from a neutron scattering viewpoint contains no information on correlations between hydrogen and all other atoms in the system. Experiments on such solutions have... 

Specific Conductance. The specific conductance depends on the total concentration of the dissolved ioni2ed substances, ie, the ionic strength of a water sample. It is an expression of the abiUty of the water to conduct an electric current. Freshly distilled water has a conductance of 0.5—2 ]lS/cm, whereas that of potable water generally is 50—1500 ]lS/cm. The conductivity of a water sample is measured by means of an a-c Wheatstone-bridge circuit with a null indicator and a conductance cell. Each cell has an associated constant which, when multiphed by the conductance, yields the specific conductance. 

The lesl is carried out by the apparatus illustrated in Figure 11.9. Waier is used and adjusted so that the discharge is. 3 10 5 null of water per minute. 

As a result, the electromotive force (EMF) of the cell is zero In the presence of fluoride ions, cerium(IV) forms a complex with fluoride ions that lowers the cerium(IV)-cerium(IIl) redox potential The inner half-cell is smaller, and so only 5 mL of cerium(IV)-cenum (III) solution is added To the external half-cell, 50 mL of the solution is added, but the EMF of the cell is still zero When 10 mL of the unknown fluonde solution is added to the inner half-cell, 100 mL of distilled water IS added to the external half-cell The solution in the external half-cell is mixed thoroughly by turning on the stirrer, and 0 5 M sodium fluonde solution is added from the microburet until the null point is reached The quantity of known fluonde m the titrant will be 10 times the quantity of the unknown fluoride sample, and so the microburet readings must be corrected prior to actual calculations... 

Han and Suhai126 reported the DFT(Yct), DFT(S/LYP), DFT(SVWN), DFT(B3LYP), and DFT(BLYP) calculations on N-methylacatemide-water complex. The N-methyla-catemide molecule may be considered one of the simplest models of the main chain of proteins. Conformational equilibria of clusters of N-methylacatemide and from one to three water molecules were studied using the DFT(B88/null), DFT(Ya), DFT(S/LYP), DFT(SVWN), DFT(B3LYP), and DFT(BLYP) calculations. The DFT(B3LYP) results compared most favorably with the ones steming from the MP2 calculations. 

The effect of turbulence in the fluid stream has been studied by Richardson and Meikle(25) who suspended a particle on a thread at the centre of a vertical pipe up which water was passed under conditions of turbulent flow. The upper end of the thread was attached to a lever fixed on a coil free to rotate in the field of an electromagnet. By passing a current through the coil it was possible to bring the level back to a null position. After calibration, the current required could be related to the force acting on the sphere. 

Cho and co-workers reported that the amplitude of the sugar proton peak following water suppression with a T null sequence correlated well with the... 

Fig. 1 Polyuria and impaired urinary concentrating function in aquaporin (AQP) null mice, a Location of AQPs in kidney tubules, b Daily urine output of mice of indicated genotype given free access to food and water, c Urine osmolality before and after a 36-h water deprivation in mice of indicated genotype. Data from Ma et al. (1997, 1998, 2000b)...

Fig. 3 Aquaporin deletion reduces osmotic water permeability in lung, but does not impair active fluid absorption, a AQP expression in epithelia and endothelia in nasopharyngeal cavity, upper and lower airways, and alveoli, b Osmotically driven water transport across the airspace/capillary barrier in perfused lungs from wildtype and indicated AQP null mice. Note the remarkable slowing of osmotic equilibration in mice lacking AQPl or AQP5. c Alveolar fluid clearance measured from the increased concentration of a volume marker 15 min after instillation of isosmolar fluid at 37°C. Where indicated, fluid absorption was inhibited by amiloride or stimulated by isoproterenol. From Bat et al. (1999) and Ma et al. (2000a)...

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