Salt uptake

Moderate soil salt concentration. These are external concentrations at which substantial osmotic adjustment in the plant is required, and could not be achieved with NaCl without compartmentation between cytoplasm and vacuole. Damage may still be attributable to excessive internal concentrations, but simply minimising salt uptake is not a sufficient answer. The concentration of osmotically active solutes within the cells has to be... 

Since the salt uptake process takes place at near neutral pH levels where the proton concentration is very low, the rate of salt adsorption by the resin system is extremely slow The rate-limiting step in thermally regenerable ion-exchange resins is the transfer of protons from the acidic to the basic sites. Rapid reaction rates in these resins have been achieved through the use of different methods. 

The rates of salt uptake by mixed-bed normal-bead resins, mixed-bed microtesins, and snake-cage resins are compared in Fig. 7. The rate for tire original mixed bed of normal-sized resins is the slowest. A slight but inadequate improvement occurs if a macroporous amine resin is used instead of a gel-type resin. Rapid rates have been achieved for the mixed-bed microresins of size 10-20 pm and the snake-cage resin of normal bead size comprising a linear poly(acryhc acid) within a macroporous amine... 

Fig. 7. Rates of salt uptake by weak electrolyte resin systems. (A) mixed bed of De-Addite G and Zeo-Karb 226 (300-1200 pm) (B) mixed bed of De-Acidite G and Z Karb 226 (10-20 pm) (C) mixed bed of Amberlite IRA-93 and Zeo-Karb 226 (300-1200 pm) (D) snake-cage resin from Amberlite IRA-93 and poly(acrylic acid) (300-1200 pm)...

F. 8. Rate of salt uptake from 0.02 N salt solution by thermally r nerable plum pudding resins containing the same De-Acidite G and Zeo-K.arb 226 plums, and 30% matrix by weight, as a function of the nature of matrix. Particle size 14-52 mesh, BSS, base resin to acid resin ratio 2 5. (1) ethyl cellulose (2) polysalt (3) crosslinked poly (vinyl alcohol) (4) normal De-Acidite G and Zeo-I b 226 mixed bed... 

Table 8. The influence of the amount and type of polysalt matrix on the rate of salt uptake by thermally regenerable plum pudding resins...

Hagenbuch, B., Meier, P.J. Sinusoidal (basolateral) bile salt uptake systems in hepatocytes. Semin. Liver Dis. 1996 16 129-136... 

Kirchner KA. Lithium asa marker for proximal tubular delivery during low salt uptake and diuretic infusion. Am J Physiol 1987 253 F188-F196. 

Oral 7-15% of ingested dose of HgCl2 absorbed from the GI tract absorption proportional to water solubility of mercuric salt uptake by neonates greater than adults... 

In the research department of a food company, the diffusion of salt into meat products is studied. Large pieces are immersed in concentrated brine (salt concentration cj), and the salt uptake per unit surface area is determined as a function of brining time (t).As expected, it is proportional to t. By means of Eq. (5.19), the effective diffusion coefficient D is estimated. For lean pork a value of 2.2 10-10 m2 s-1 results, for back fat (untrimmed bacon) only 10 11 m2 s 1. As a check it is determined in a separate experiment what the salt content is at a distance of 1 cm from the outside after 5 days of brining. By using Eq. (5.21), it is expected that in the lean pork c (expressed per kg water) will equal nearly 0.5ci, whereas it... 

Figure 9. Change in chloroplast size on addition of various substances. Halo-genides were added in 30 mM increments, which resulted in shrinkage. These additions were followed by valinomycin (val) at a concentration of 2 /xM, which resulted in expansion. Changes in chloroplast size at 20°C were monitored by changes in the apparent absorbance of the chloroplast suspension at 535 nm (43). Note different slopes of the absorbance decrease seen on addition of valinomycin, which increases the K+ permeability of the chloroplast envelope. As in the presence of the antibiotic, K+ diffusion is not limiting the rate of salt uptake, different slopes indicate different anion fluxes. For experimental conditions see Ref. 91.

Different small intestinal sites of absorption for different micellar constituents have also been an argument for uptake of monomers instead of micelles. Whereas the major part of the lipolytic products are absorbed in the proximal part of jejunum, the site of bile salt uptake has been said to be the distal ileum. Recent investigations of the quantitative role of different parts of the small intestine for bile salt absorption suggest that the role of the distal ileum has been overestimated. Sklan et al. [73] found that about 50% of bile salts of endogenous origin were absorbed in the proximal half of the rat small intestine in vivo. A similar investigation was performed by McCUntock and Shiau [74], who injected a bolus dose of bile salts into the jejunum of rats with a bile fistula. They found that 60% of taurocholate was absorbed before the bolus reached distal ileum. 

Cholestasis is a condition characterized by impaired flow of bile, due to physical obstruction of the biliary tree or decreased bile secretion by the liver. Cholestasis produces alterations of enzyme activity in the liver (cytochrome P450) as well as altered transporter expression, with associated effects on drug clearance. As discussed previously, cholestasis can occur through inhibition of the canalicular membrane transporter, BSEP. In response to cholestasis, however, the liver has adaptive mechanisms to minimize cellular accumulation of toxic bile salts. These include upregulation of MRP3 to increase sinusoidal efflux, and downregulation of Na -taurocholate cotransporting polypeptide (NTCP), which mediates bile salt uptake from the blood to the liver. 

The experiments reported here were formulated with the intention of uncovering, in as much detail as possible, the environment existing within a cellulosic fiber in contact with an ionic aqueous phase. Measurements were made at room temperature ( 25°C) and at 90°C. The salt used most extensively was NaaS04 and measurements were made on the uptake of both cation and anion as a function of the concentration of the bath at 25°C and 90°C and as a function of pH at 25°C. In addition, the uptake of the direct dye, Chrysophenine G, and the effect of the dye on the salt uptake were studied at 90°C. It was also necessary to perform some measurements relating to the stability of the fibers. Finally, some measurements were made on the uptake of the Br ion from NaBr solutions. 

Thus it is quite certain that, over the range of concentrations and dye/salt ratios used, the presence of dye lowers the salt uptake as compared with the value when no dye is present. It is probable that the amount of salt taken up at a given concentration of salt in the bath decreases as the dye/salt ratio increases. However, for the most part, the dilferences between the curves for the various dye/salt ratios fall within the precision of the experimental results. 

The research effort in perfecting a resin system capable of efficient performance in a thermally regenerate ion-exchange process can be divided into two distinct phases 2U 229>- (i) selection of mixtures of weakly basic and weakly acidic resins as suitable systems and extensive study of the relationship between the chemical structure, basicity, acidity, and thermal stability of ion-exchange resins of the weak electrolyte type, and (ii) efforts put forth to increase the rate of salt uptake and capacity of thermally regenerable systems. 

The effects of acid waters on fish physiology are similar to those caused by aluminium. For example, fish exposed to acid waters suffer a reduction in blood salts, which could be attributed to an impairment of salt uptake in the gills, and increased sodium use from the brown trout. The salt balance of freshwater fish is maintained by active, energy consuming exchange of ions across the gill membrane and excretion in the urine. Therefore in fish in waters of pH levels between 4.0 and 4.3, particular physiological effects are known to appear in respiration, metabolism and cell volume, and in some cases death can occur. 

Yield measurements could therefore be summarized by the facts that the best salt uptake was gained by salt injection and that salt addition was most effective in wild post rigor mortis cod muscle. Drip measurements also showed that superchilling had a positive effect on the yield, in correlation to slower spoilage mechanisms than in the chilled samples. Salt injections also showed some positive effect on the drip loss, especially in the pre rigor fish. 

Salt measurements on the samples showed that the samples had a salt content between 0.3 and 0.4%. When salt was added by salt injection the salt content of the wild post rigor group increased to 0.6% NaCl, but no significant change was found in the salt content for salt injected farmed or wild pre rigor samples. This indicated that only the wild post rigor muscle had an effective salt uptake in the study. 

According to Table 2 it could be seen that the storage temperature (chilled or superchilled) did not have a major effect on the relaxation times measured. Longer relaxation times were on the other hand obtained in the wild cod samples than in the farmed cod samples, especially in the post rigor samples regardless of processing method in correlation to the water content of the samples. Salting also increased the relaxation times in the wild cod but had no or little effect on the farmed cod. This is in correlation to the less salt uptake observed in the farmed cod. 

The study showed that a significant diffo ence can be found between the muscle structure and characteristics of wild and farmed cod and that choosing the time of processing (pre or post rigor mortis) was of great importance. The farmed cod did not show a similar salt uptake as the traditional wild post rigor mortis processed cod. This showes even further that wild cod can not be entirely replaced by farmed cod in the processing of various products. 

Salt uptake rate in muscle foods depends on many technological parameters, one of them being the availability of the water in a muscle which is a fimction of the quality of the raw material. Another important parameter is availability and local concentration of the sodium ions at the interface with the muscle, a MRI can be used to visualize variations in the sodium distribution of similar raw materials salted or processed by different methods, and thus serve as a tool for the process optimization. 

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