NaCl is a major component of the extracellular fluid. The kidney plays critical roles in the maintenance of the homeostasis of the body fluid. The regulation of NaC1 balance is accomplished by glomerular filtration followed by tubular reabsorption of NaCl. The evolution of vertebrates from fishes to mammals were accomplished by adjustment of animals to changes in external environments from sea to terrestrial. The development of diluting nephron segments made it possible for fishes to adapt from seawater to fresh water. Such segments were succeeded to reptiles and amphibians. The development of renal medulla in the avian kidney made it possible for birds to adapt to the terrestrial environment by producing concentrated urine, which is established by the countercurrent multiplication system utilizing active NaC1 transport in Henle's loop. In mammals, urine concentrating ability was much advanced due to additional contribution of urea in the countercurrent system of the renal medulla. The evolutional changes of the renal medulla from birds to mammals can be traced through the ontogeny of the mammalian kidney, where avian type nephron was observed during the fetal period.
Based on tight relationship between salt and hypertension, characteristic features of salt-sensitive hypertension will be reviewed. As blood pressure becomes elevated more sensitively to salt intake, glomerular capillary pressure is more elevated and night-time reduction in blood pressure is more diminished, resulting in glomerular hypertension and nondipper type of circadian blood pressure rhythm. In this way, organ damage including stroke is enhanced in saltsensitive hypertension. Salt intake restriction, on the other hand, is expected to reduce cardiovascular events, especially in salt sensitive hypertension.
First, definition of the word (mineral) and grouping of minerals were introduced. Next, the data showing how sodium restriction caused metabolic changes in minerals stored in the bone (Na, Ca, Mg) were presented. Then, results of human mineral balance studies done in The National Institute of Nutrition (Tokyo) were shown. With these data, interrelations between minerals (Na, K, Ca, Mg, P) and estimated average requirements (EARs) were proposed.
Sodium ion in salt (NaCl) excite taste cells in the taste buds by penetrating a specific ion channel called ENaC. The neural information is sent to the brain via the taste nerves and is processed to elicit salty taste. Animals prefer salt solutions at the isotonic concentration (0.15mol/l) and reject at the hypertonic concentrations. Females like salty taste more than males do. Under the salt appetite condition, animals show high sensitivity to weak salt solutions and low sensitivity to strong ones to facilitate ingestion of Sodium ion by changing the hedonic value. Brain mechanisms of palatability are described in terms of brain substances: palatability is enhanced by benzodiazepine derivatives and β-endorphin, the motivation to ingest is performed by dopamine and the ingestive behavior is executed by orexin.
Effects of various factors such as coexistence of basic ion, five basic taste and gelling agent, on the salt taste intensity of sodium chloride are summarized. The salt taste intensity was significantly lowered when NaCl was substituted with more than 20% KCl, or more than 10% MgCl2. However, there was no significant difference on the preference for the 20% KCl or10% MgCl2 substituted NaCl solutions. Addition of small amount of salt enhanced the sweet taste. When salt is tasted for the second time, after tasting concentrated sugar solution, the salt taste intensity became stronger. Salt taste intensity/NaCl concentration in the solid food was expressed as the taste efficiency ratio. The salty taste efficiency ratio of the tested foods was generally lower than the actual amount of salt, which means that we take more salt than we feel when we eat the foods. The relationship between the salty taste efficiency ratio and physical property of foods, and the methods to determine the salty taste efficiency are also discussed.
A novel flow injection system is presented for monitoring sodium ion in brine based on a catalytic decomposition of a chelate-type chromoionophore with highly concentrated sodium ions. Bis (1, 4, 7, 10, 13-pentaoxa-16-aza-cyclooctadecane-N-carbodithioato) cobalt (II)(Co-A18CC) was newly synthesized and examined as a chelate-type chromoionophore. The catalytic decomposition of Co-A18CC was highly specific for sodium ion. Various analytical parameters of the reverse-mode FIA for monitoring sodium ion were investigated, and optimal conditions and a manifold configuration were established. A linear calibration was obtained for sodium ion in the range of 0-5 mol dm-3 (Relation coefficient: 0.996). Minor components of brine, such as magnesium, bromide, sulfate and carbonate, did not interfere with the decomposition reaction. Artificial brine samples were examined for the purpose of applying the FIA method to the monitoring of the brine process, resulting in a satisfactory performance for within-a-day monitoring.
A cool water jet is discharged horizontally into a water vessel with thermal stratification, in order to examine the effect of thermal stratification on the behavior of cool jet diffusion. The discharged cool jet sinks gradually by a negative buoyancy near the discharging nozzle. The cool jet is warmed by the effect of thermal stratification and then its negative buoyancy is weakened. It is found that the flow of the cool jet behaves as an overshoot due to inertia and then its flow direction turns upwards. The rebounded flow raises the equivalent density depth. The flow streams horizontally and keeps its depth clearly by the effect of thermal stratification. It is clarified that thermal stratification affects the behavior of a cool jet. Large eddy simulations(LES)using a non-isotropic Dynamic Smagorinsky model is performed and its numerical result is compared with the experimental results. The numerical result corresponds to experimental ones accurately in terms of velocities and the depth of the jet axis. It is confirmed that this model is available for simulation of the behavior of a cool jet into thermal stratification.
The use of an alternating-current (AC) electric field is investigated as a method for promoting the concentration of seawater. The effects are investigated based on the rate of weight loss of seawater in an AC electric field of 3.6kV/m, and at temperatures of 10, 25 and 50°C.Increasing the temperature results in an increase in the evaporation rates by 1.5-5.2times the untreated rate in the first hour, while increasing the initial concentration of seawater reduces the evaporation rate. Results obtained at a field strength 3.6kV/cm under ambient conditions of 25°C and 50% relative humidity are comparable and in some cases better than those at 50°C, suggesting that the application of an intense AC electric field may be an attractive alternative to conventional thermal processing.
A silnple and rapid method is presented for the determination of boron at ppb to sub-ppm levels in sodium chloride, in which in-line preconcentration/separation is directly coupled with spectrofluorimetric detection in a flow injection system. Boron in the buffered sample solution at pH 10 was adsorbed on a small Sephadex G-25 gel column and desorbed with a small volume of 0.10mol/l HCl, which allowed effective preconcentration/separation of boron from a large excesss of NaCl matrix and other coexisting elements. Boron was detected by measuring the fluorescence intensity due to its complex formation with chromotropic acid (1,8-dihidroxy-3, 6-naphthalenedisulphonic acid). Various parameters affecting analytical sensitivity and precision were investigated, and optimal conditions and manifold configurations were established. A linear calibration using a 5 m sample loop was obtained for boron in the range of 0-15 ppb. The relative standard deviation was 1.8% for 5.0 ppb boron solution and the estimated limit of detection was ca.0.2 ppb. The limit of detemlination defined as five times the limit of detection is ca.6 ppb in sodium chloride when 3mol/l sodium chloride solution is applied for analysis. The present FIA system is rapid and simple and can be readily applied to determine boron at sub-ppm to several tens of ppb levels in various salt samples. Only 9 min is required for analytical measurement after sample injection and no complicated manual operation is involved.