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PubMed1998

The effect of different rehydration drinks on post-exercise electrolyte excretion in trained athletes.

Eight well-trained cyclists were dehydrated (median [P25-P75 percentiles]) 3.21 [2.97-3.56]% of body mass by cycling in the heat (28 C). During the first 2 h of recovery, the subjects randomly ingested ad libitum either a caffeinated soft drink (CC), a low Na+ mineral water (MW), or an isotonic carbohydrate-electrolyte solution (CES). Fluid intake and urine loss amounted respectively to 2.77 [2.34-2.85] kg, 1.00 [0.82-1.20] kg for CC, 2.15 [1.86-2.79] kg, 0.96 [0.40-1.49] kg for MW, and 2.86 [2.15-3.58] kg, 1.10 [0.86- 1.50] kg for CES. Electrolyte retention was calculated from electrolyte intake with the drink and loss with the urine. Consumption of CC and MW which were low in electrolytes resulted in marked loss of Na+, K+, Cl-, Mg2+ and Ca2+. Consumption of CES resulted in Na+, Mg2+ and Ca2+ retention while K+ and Cl- loss were not influenced. The significantly lower Na+, Mg2+ and Ca2+ loss with CES compared to both CC and MW may be explained by its higher electrolyte content in CES, compared to CC and MW, which only had minor amounts of these electrolytes. Furthermore, it was shown that CC potentiated urinary Mg2+ and Ca2+ excretion. It is concluded that: 1) Post-exercise MW or CC ingestion results in a negative electrolyte balance, 2) Caffeine containing beverages potentiate Mg2+ and Ca2+ excretion; 3) Consumption of CES containing moderate amounts of Na+, Mg2+ and Ca2+ results in sufficient replacement to compensate for urinary losses.

Adult↗

PubMed2003

The influence of a 6.5% carbohydrate-electrolyte solution on performance of prolonged intermittent high-intensity running at 30 degrees C.

Nine male student games players consumed either flavoured water (0.1 g carbohydrate, Na+ 6 mmol x l(-1)), a solution containing 6.5% carbohydrate-electrolytes (6.5 g carbohydrate, Na+ 21 mmol x l(-1)) or a taste placebo (Na+ 2 mmol x l(-1)) during an intermittent shuttle test performed on three separate occasions at an ambient temperature of 30 degrees C (dry bulb). The test involved five 15-min sets of repeated cycles of walking and variable speed running, each separated by a 4-min rest (part A of the test), followed by 60 s run/60 s rest until exhaustion (part B of the test). The participants drank 6.5 ml x kg(-1) of fluid as a bolus just before exercise and thereafter 4.5 ml x kg(-1) during every exercise set and rest period (19 min). There was a trial order effect. The total distance completed by the participants was greater in trial 3 (8441 +/- 873 m) than in trial 1 (6839 +/- 512, P < 0.05). This represented a 19% improvement in exercise capacity. However, the trials were performed in a random counterbalanced order and the participants completed 8634 +/- 653 m, 7786 +/- 741 m and 7099 +/- 647 m in the flavoured water (FW), placebo (P) and carbohydrate-electrolyte (CE) trials, respectively (P = 0.08). Sprint performance was not different between the trials but was impaired over time (FW vs P vs CE: set 1, 2.41 +/- 0.02 vs 2.39 +/- 0.03 vs 2.39 +/- 0.03 s; end set, 2.46 +/- 0.03 vs 2.47 +/- 0.03 vs 2.47 +/- 0.02 s; main effect time, P < 0.01). The rate of rise in rectal temperature was greater in the carbohydrate-electrolyte trial (rise in rectal temperature/duration of trial, degrees C x h(-1); FW vs CE, P < 0.05; P vs CE, N.S.). Blood glucose concentrations were higher in the carbohydrate-electrolyte than in the other two trials (FW vs P vs CE:rest, 4.4 +/- 0.1 vs 4.3 +/- 0.1 vs 4.2 +/- 0.1 mmol x l(-1); end of exercise, 5.4 +/- 0.3 vs 6.4 +/- 0.6 vs 7.2 +/- 0.5 mmol x l(-1); main effect trial, P < 0.05; main effect time, P < 0.01). Plasma free fatty acid concentrations at the end of exercise were lower in the carbohydrate-electrolyte trial than in the other two trials (FW vs P vs CE: 0.57 +/- 0.08 vs 0.53 +/- 0.11 vs 0.29 +/- 0.04 mmol x l(-1); interaction, P < 0.01). The correlation between the rate of rise in rectal temperature (degrees C x h(-1)) and the distance completed was -0.91, -0.92 and -0.96 in the flavoured water, placebo and carbohydrate-electrolyte conditions, respectively (P < 0.01). Heart rate, blood pressure, plasma ammonia, blood lactate, plasma volume and rate of perceived exertion were not different between the three fluid trials. Although drinking the carbohydrate-electrolyte solution induced greater metabolic changes than the flavoured water and placebo solutions, it is unlikely that in these unacclimated males carbohydrate availability was a limiting factor in the performance of intermittent running in hot environmental conditions.

Adult↗

PubMedDate not supplied

Probing the dynamics of matrix hydration in the presence of electrolytes.

The aim of our work was to probe the mechanisms associated with induced matrix stiffening via textural analysis as a consequence of in situ electrolyte interactions within hydroxypropyl-methylcellulose (HPMC) and polyethylene oxide (PEO) matrices in relation to their role in controlling the release of highly soluble drugs such as diltiazem hydrochloride (>50% water soluble at 25 degrees C). The dynamics of HPMC and PEO matrix swelling during hydration in the presence of appropriate electrolytes intended to induce constant drug release rates from simple monolithic systems are influenced by continuously shifting peripheral matrix stiffening toward the matrix core in a manner dependent on electrolyte content and hydration time. Matrix erosion for HPMC and PEO controls (i.e., without electrolyte) follow linear dissolution kinetics (r2 > 0.97), while formulations with electrolyte characteristically undergo a square root of time decline in weight. The swelling potential of the electrolyte-containing matrices, influenced by the boundary infiltration process, reflected considerable suppression during the first 2 hr of exposure to medium, while subsequent events differed in both polymers. In view of these differences, simultaneous measurements in textural transitions and electrolyte conductivity showed that PEO has a higher affinity for water molecules than does HPMC.

Diltiazem↗

PubMed2005

Some interactions between gastrointestinal function and fluid and electrolyte homeostasis.

PURPOSE OF REVIEW: The gastrointestinal tract plays an important role in the maintenance of fluid and electrolyte balance, and its diseases cause disturbances in that balance. Conversely, fluid and electrolyte disorders may disturb gastrointestinal function. The purpose of this review is to highlight some recent literature describing these interactions against a background of fluid and electrolyte physiology in normal and disease states. RECENT FINDINGS: Gastrointestinal disease is the most common cause of fluid and electrolyte disturbance, and this can usually be corrected by the oral route, although parenteral replacement is sometimes required. The use of self-administered subcutaneous fluid and electrolyte administration at home is described. Reduced microcirculatory perfusion as a result of hypovolaemia or a rise in blood viscosity after packed cell transfusion may precipitate gut necrosis, particularly during enteral feeding. Positive salt and water balance postoperatively of as little as 3 l impairs gastrointestinal function and increases complications. Other states of salt and water retention may have similar effects, although further research is needed to define this. SUMMARY: The role of the gastrointestinal tract in controlling fluid and electrolyte balance is underestimated. Conversely, the effect of fluid and electrolyte imbalance on gastrointestinal function is apparent, but requires more research.

Fluid Therapy↗

PubMed2005

Electrolyte abnormalities at diagnosis of acute lymphocytic leukemia may be a clue for renal damage in long-term period.

The objective of this study was to determine the frequency of electrolyte perturbations and their relationship with leukemic status before and after chemotherapy in patients with acute lymphocytic leukemia. Blood biochemistry, liver and renal function tests, and renal sonograms were examined at diagnosis and during induction therapy in 334 patients. Renal and electrolyte disturbances were then studied in 116 patients between 3 and 110 months after cessation of the St. Jude chemotherapy treatment protocol. Glomerular filtration rate, electrolyte, protein, and beta-2-microglobulin levels were determined in fresh urine samples, and serum electrolyte levels were examined in blood samples. Renal sonographic examinations and scintigraphic examinations were performed with DMSA and MAG-3. Renal leukemic involvement was detected by sonographic examination in 32 patients who had also presented with hyperphosphatemia or hyperuricemia. Patients with electrolyte disorders at diagnosis were less likely to have tumor lysis syndrome during induction chemotherapy. This may be explained by correction of their electrolyte disorders at the time of diagnosis, which may protect them from tumor lysis syndrome. Hypocalcemia and hyponatremia at the time of diagnosis were found to be significant initial risk factors for renal scan abnormalities and microproteinuria, respectively, during the late therapy period (P < 0.05). Electrolyte abnormalities and renal changes were commonly observed before and after therapy for leukemia. Patients presenting with hypocalcemia and hyponatremia should be examined for microproteinuria and should undergo renal scanning during the late therapy period.

Adolescent↗

PubMed1994

A nonlinear finite element model of the electrode-electrolyte-skin system.

This study presents a two-dimensional finite element model of the electrode-electrolyte-skin system which takes into account the nonlinear behavior of the skin with respect to the amplitude of the voltage. The nonlinear modeling approach has practical value for studies related to transcutaneous stimulation (e.g. maximizing the dynamic range of sensory substitution systems, optimization of TENS, optimization of transcutaneous cardiac pacing, etc.). The model has three main regions: 1) the electrolyte; 2) the skin; and 3) the body. The model consists of 364 nodes, 690 elements and was generated on a MacIntosh II using a version of FEHT (Finite Element for Heat Transfer) adapted for electromagnetics. The electrodes are equipotential lines and the electrolyte is modeled as a pure resistive region with constant conductivity. Although the electrode-electrolyte interface can introduce nonlinearities, we did not take them into account because the skin displays a much higher impedance. The skin is modeled as a nonlinear material with the conductivity dependent on the applied voltage. To account for the mosaic structure of the skin, we used ten different nonlinear subregions of five different values of breakdown voltage. The region designated "body" models the effects of the resistance associated with the dermis and the tissues underneath the skin, and has a constant high conductivity. We studied the effects of two different electrolytes on the comfort of stimulation and found that there was less potential pain delivered when high-resistivity electrolytes were used. This was due to the larger nonuniformities in the current density distribution which appeared for low-resistivity electrolytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Electric Conductivity↗

PubMed2005

Enhancement of ionic conductivity of PEO based polymer electrolyte by the addition of nanosize ceramic powders.

The ionic conductivity of polyethylene oxide (PEO) based solid polymer electrolytes (SPEs) has been improved by the addition of nanosize ceramic powders (TiO2 and AL2O3). The PEO based solid polymer electrolytes were prepared by the solution-casting method. Electrochemical measurement shows that the 10 wt% TiO2 PEO-LiClO4 polymer electrolyte has the best ionic conductivity (about 10(-4) S cm(-1) at 40-60 degrees C). The lithium transference number of the 10 wt% TiO2 PEO-LiClO4 polymer electrolyte was measured to be 0.47, which is much higher than that of bare PEO polymer electrolyte. Ac impedance testing shows that the interface resistance of ceramic-added PEO polymer electrolyte is stable. Linear sweep voltammetry measurement shows that the PEO polymer electrolytes are electrochemically stable in the voltage range of 2.0-5.0 V versus a Li/Li+ reference electrode.

Aluminum Oxide↗

PubMed1996

Metabolic changes and nutrient repletion in lambs provided with electrolyte solutions before and after feed and water deprivation.

Providing feeder calves and lambs with electrolyte solutions before and(or) after a transport period could potentially reduce tissue shrink and speed repletion of nutrients and weight that are lost during transport. This trial was conducted to determine metabolic changes and nutrient repletion in lambs provided with electrolyte solutions before and after feed and water deprivation. Solutions were 1) deionized water, 2) ES1 (g/10 L: NaCl, 2.0; K carbonate, 2.8; Mg sulfate.7H2O, 2.0; equal mixture of amino acids [Lys, Thr, Phe, His, Trp, Met, Leu, Ile, and Val], .45; and phosphoric acid to pH 7.0), 3) ES2 (twice the concentrations as in ES1), and ES3 (g/10 L: NaCl 2.0; K carbonate, 8.0; Mg sulfate.7H2O, 4.0; amino acid mixture from ES1, .45; and phosphoric acid to pH 7.0). Eight Suffolk x Hampshire crossbred lambs (average BW 35 +/- 2 kg) were used in an 8 x 8 Latin square design with treatments arranged in a 2 x 4 factorial. Main treatments consisted of two deprivation electrolyte solutions (deionized water or ES1) and four realimentation electrolyte solutions (deionized water, ES1, ES2, and ES3). Lambs were limit-fed (600 g/d, as-fed basis) before and after a 3-d feed and water deprivation phase. Lambs provided the ES1 solution during the pre-deprivation phase had greater (P < .05) Na, Mg, Zn retention during the pre-deprivation phase, had greater (P < .05) Na and Mg losses during the 3-d deprivation phase, and greater (P < .05) cumulative Na, Cu, and Fe retentions than lambs given deionized water during the pre-deprivation phase. Compared to lambs provided water, lambs provided the ES1 solution during the realimentation phase had greater Na retention but similar K, Mg, and water retentions. However, when the concentration of electrolytes in the solution was doubled (i.e., ES2 solution), Na, K, and Mg retentions were increased (P < .05) compared with those of lambs provided deionized water or the ES1 solution. These results suggest that as the length or severity of the stress period increases, the concentration of electrolytes in the electrolyte solution may need to be increased to improve nutrient balance.

Absorption↗

PubMed2005

Effect of repeated oral administration of hypertonic electrolyte solution on equine gastric mucosa.

REASONS FOR PERFORMING STUDY: Electrolyte supplementation is common in horses during endurance competitions, but the effect on the gastric mucosa is unknown. HYPOTHESIS: Repeated oral administration of hypertonic electrolyte solution is associated with exacerbation of gastric ulcers in mature horses. METHODS: The study design was a randomised, blinded, crossover trial. Fourteen horses were divided randomly into equal groups and administered either 60 ml water (placebo) or 56.7 g commercial electrolyte supplement mixed with 60 ml water by dose syringe orally once an hour for 8 h. The minimum concentration of individual constituent electrolytes/28.35 g dry commercial product used was: sodium (5528 mg); chloride (11,886 mg); potassium (3657 mg); calcium (754 mg); and magnesium (153 mg). Gastric lesions were scored prior to and after oral treatments, and analysis of variance procedures were then performed. RESULTS: Administration of hypertonic electrolytes resulted in a significant increase in mean ulcer number (P = 0.0174) and severity (P = 0.0006) scores in the nonglandular stomach. Mean ulcer number score was 3.6 and mean ulcer severity score 2.7 after hypertonic electrolyte treatment. CONCLUSIONS: Oral hypertonic electrolyte administration to horses in this model was associated with exacerbation of gastric ulcers. POTENTIAL RELEVANCE: Our findings suggest that one schedule of electrolyte supplementation used commonly in endurance horses may be harmful to the gastric mucosa.

Administration, Oral↗

PubMed1987

Effects of dietary crude protein, electrolyte balance, and photoperiod on growth of broiler chickens.

Three experiments were conducted with broiler chicks to study the effects of dietary electrolyte balance, dietary crude protein level, and photoperiod on performance. Increasing the electrolyte balance (Na + K -Cl) from about 200 meq/kg to 350 meq/kg or more improved gain and feed consumption of chicks fed high protein (28.6%) diets but depressed gain and feed consumption of chicks fed low protein (14.3%) diets. Neither sex nor photoperiod affected to nature or magnitude of the crude protein X electrolyte balance interaction, although birds housed under 16L:8D had significantly higher concentrations of plasma ammonia than did those housed under 23L:1D. Chicks fed diets containing a high vs. a low electrolyte balance had significantly higher concentrations of plasma uric acid and significantly lower kidney asparaginase activities. Electrolyte effects on kidney asparaginase activity were not affected by diet crude protein content. Results indicate that the electrolyte balance that provides for optimum growth is dependent upon dietary crude protein concentration. Further, diet electrolyte effects on metabolic acid-base homeostasis are not related to their effects on growth.

Animals↗

PubMed1992

[Determination of electrolytes in serum and plasma].

In clinical chemistry two different quantities are determined for electrolytes: 1) Electrolyte concentration (total) in serum (S) e.g. S-sodium (mmol/l), S-calcium (mmol/l). 2) Electrolyte concentration (ionized) in serum water [S(W)] e.g. S(W)-sodium, ionized (mmol/kg), S(W)-calcium, ionized (mmol/kg) ad 1) For the determination of the electrolyte concentration in serum, various methods are used: Sodium, potassium: Flame atomic emission spectrometry, ion-selective electrodes after dilution of the sample, enzymatic methods; Chloride: Coulometry, absorption spectrometry after chemical reaction, enzymatic method; Calcium, magnesium: Flame atomic absorption spectrometry, flame atomic emission spectrometry (calcium), absorption spectrometry after chemical reaction, enzymatic method (magnesium). A safe and unambiguous medical interpretation of sodium and chloride ion concentration in serum is not possible without knowledge of the water concentration or of the lipid and protein concentration of the individual sample. The same holds true--even though for some other reasons--for calcium concentration in whole serum. The reference intervals of the pertinent ions are valid only for samples, which are "normal" with respect to the size of the electrolyte-free compartment and--depending on the method--the amount of complex-binding ions. ad 2) For the determination of the concentration of the "ionized" or "free" fraction of sodium, potassium, calcium, and magnesium in serum water (or the extracellular water phase of whole blood) the following method is only applicable: Ion selective electrode without dilution of the sample. A save medical interpretation of the ionized electrolyte concentration in serum water is possible without knowledge of the water concentration of the individual sample, because these quantities are independent from the size of the electrolyte-free compartment.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Chemical Analysis↗

PubMed1990

Incidence of acid-base and electrolyte disturbances in a general hospital: a study of 110 consecutive admissions.

To establish the overall frequency distribution and combination of acid-base and electrolyte disturbances as they occur in a general population requiring hospital care, we studied arterial blood gases and plasma electrolytes (sodium, potassium and chloride) in 110 consecutive patients (age = 68 +/- 8 SE; 64 M, 46 F) at the time of admission to a general medical ward. Disturbances were defined on the basis of the standard pH/pCO2 plot and the normal (mean +/- 2 SD) electrolyte range for our laboratory. Sixty-two patients (56%) showed a disturbance in acid base equilibrium: acidosis: respiratory 16, metabolic 6; alkalosis: respiratory 26, metabolic 10; in 4/62 the acid base disturbance was mixed. In 47 of the 62 patients, the acid base imbalance were associated with electrolyte derangements (low PNa+, 12; high PNa+, 1; low PK+, 10; high pK+, 7; increased anion gap, 17). Electrolyte disturbances with a normal acid base status were detected in only 2 patients. Of significance, in 7 of the 58 individuals considered to have a "pure" acid base disturbance on the basis of the pH/pCO2 plot (5 respiratory alkalosis; 1 respiratory acidosis; 1 metabolic alkalosis), a widened anion gap revealed that the acid-base change was mixed, i.e. there was a concomitant component of metabolic acidosis. Thus, the total number of mixed acid base equilibrium disorders were eleven. This study emphasizes the frequent incidence of acid base and electrolyte disorders, very often in combination, among unselected adult patients admitted to a general medical ward. In addition it reinforces that a high prevalence of hidden cases of mixed acid base disturbances can be recognized by concomitant analysis of acid base and electrolyte parameters, including anion gap calculation.

Acid-Base Imbalance↗

PubMed1981

Acid-base and electrolyte alterations associated with salivary loss in the pony.

Esophageal fistulas were made in 6 ponies to evaluate whole blood acid-base values and serum and salivary electrolyte alterations associated with salivary depletion. Acid-base and electrolyte values remained within normal ranges for 15 days in 3 control ponies fed a pelleted diet through nasogastric tubes. In 6 ponies with esophageal fistulas that were fed the same diet through esophagostomy tubes, hypochloremia and hyponatremia developed during the same period. Serum K concentrations were only marginally depleted, probably because of dietary replacement. Salivary depletion resulted in transient metabolic acidosis from bicarbonate lost in saliva followed by progressive metabolic alkalosis. The alkalosis probably resulted from renal compensation of electrolyte imbalances. Salivary electrolytes were in high concentrations, probably because of increased salivary flow rates. Initial saliva was rich in Na, Cl, and K, but progressive reduction in salivary Na and Cl concentrations occurred during the 5-day collection period. These electrolyte savings could be explained by dietary influences and hormonal control of electrolyte transport in salivary ducts. Therapy for correction of acid-base and electrolyte alterations was also discussed.

Acid-Base Imbalance↗

PubMed1981

Changing feeding trends as a cause of electrolyte depletion in infants with cystic fibrosis.

Between June 1979 and June 1980, 16 infants with cystic fibrosis (CF) were cared for at the James Whitcomb Riley Hospital for Children. Five of these children (average age 5.8 months) had a total of eight episodes of electrolyte depletion, with six episodes unassociated with high environmental temperature, fever, or significant gastrointestinal symptoms. Their primary symptoms were poor weight gain and anorexia. According to their dietary records, these five infants, at the time of their initial presentation, had an average electrolyte intake of 8 mEq of sodium, 12 mEq of potassium, and 10 mEq of chloride per day. All infants had been fed either standard infant formula or breast milk. Infant feeding surveys indicate that the estimated average sodium intake of 6-month-old infants has decreased from 45 mEq/day in 1965 to 15 mEq/day since 1977 when manufacturers stopped adding salt to baby foods. In addition, since 1971 the percentage of infants 6 months age receiving breast milk or standard infant formula rather than cow's milk, which is higher in sodium content, has increased from 33% to 72%. This decreased salt intake places the infant with CF at greater risk for electrolyte depletion than in the past. It is expected that a larger percentage of infants with CF will have electrolyte depletion as their initial symptom especially during periods of increased sweating or when electrolyte losses are experienced during gastrointestinal illnesses. CF should be suspected in any infant with electrolyte depletion, and infants known to have CF need daily salt supplementation. Serum electrolytes should be measured if the infant is experiencing weight loss or anorexia, particularly during periods of excessive salt losses.

Breast Feeding↗

PubMed2002

Adsorption of nonionic mixtures at the air-water interface: effects of temperature and electrolyte.

Specular neutron reflection has been used to investigate the effects of temperature and added electrolyte on the adsorption of nonionic surfactants and nonionic surfactant mixtures at the air-water interface. For the alkyl poly-oxyethylene oxide nonionic surfactants, C(n)EO(m), the adsorption at the air-water interface is independent of temperature for surfactants with shorter ethylene oxide groups, whereas there is an increasing tendency for increased adsorption with temperature for surfactants with longer ethylene oxide groups. The addition of "salting in" (sodium thiocyanate, NaSCN) and "salting out" (sodium chloride, NaCl, sodium sulphate, Na2SO4) electrolyte results in reduced and enhanced adsorption, respectively, for C12EO8, whereas both types of electrolyte result in enhanced adsorption for C12EO12. The addition of electrolyte does not substantially alter the temperature dependence of the adsorption of the pure monolayers. For the nonionic mixtures of C12EO3/C12EO8 increasing temperature results in a surface richer in the least surface-active component, C12EO8. For the same nonionic mixture, the addition of "salting in" and "salting out" electrolyte results in an reduced and increased adsorption, respectively. The addition of "salting in" electrolyte results in a surface more rich in C12EO3, whereas for the addition of both "salting in" and "salting out" electrolyte the surface composition is essentially unaltered.

Journal Article↗

PubMed2004

Effects of electrode density and electrolyte spreading in dense array electroencephalographic recording.

OBJECTIVE: High-density EEG recording offers increased spatial resolution but requires careful consideration of how the density of electrodes affects the potentials being measured. Power differences as a function of electrode density and electrolyte spreading were examined and a method for correcting these differences was tested. METHODS: Separate EEG recordings from 8 participants were made using a high-density electrode net, first with 6 of 128 electrodes active followed by recordings with all electrodes active. For a subset of 4 participants measurements were counterbalanced with recordings made in the reversed order by drying the hair after the high-density recordings and using a fresh dry electrode net of the same size for the low-density recordings. Mean power values over 6 resting eyes open/closed EEG recordings at the 6 active electrodes common to both recording conditions were compared. Evidence for possible electrolyte spreading or bridging between electrodes was acquired by computing Hjorth electrical distances. Spherical spline interpolation was tested for correcting power values at electrodes affected by electrolyte spreading for these participants and for a subset of participants from a larger previous study. RESULTS: For both the complete set and the counterbalanced subset, significant decreases in power at the 6 common electrodes for the high-density recordings were observed across the range of the standard EEG bands (1-44 Hz). The number of bridges or amount of electrolyte spreading towards the reference electrode as evidenced by small Hjorth electrical distances served as a predictor of this power decrease. Spherical spline interpolation increased the power values at electrodes affected by electrolyte spreading and by a significant amount for the larger number of participants in the second group. CONCLUSIONS: Understanding signal effects caused by closely spaced electrodes, detecting electrolyte spreading and correcting its effects are important considerations for high-density EEG recordings. A combination of scalp maps of power density and plots of small Hjorth electrical distances can be used to identify electrodes affected by electrolyte spreading. Interpolation using spherical splines offers a method for correcting the potentials measured at these electrodes.

Adult↗

PubMed2004

Electrophoretic mobility of a highly charged colloidal particle in a solution of general electrolytes.

For a highly charged particle in an electrolyte solution, counterions are condensed very near the particle surface. The electrochemical potential of counterions accumulated near the particle surface is thus not affected by the applied electric field, so that the condensed counterions do not contribute to the particle electrophoretic mobility. In the present paper we derive an expression for the electrophoretic mobility mu(infinity) of a highly charged spherical particle of radius a and zeta potential zeta in the limit of very high zeta in a solution of general electrolytes with large ka (where k is the Debye-Hückel parameter) on the basis of our previous theory for the case of symmetrical electrolytes (H. Ohshima, J. Colloid Interface Sci. 263 (2003) 337). It is shown that zeta can formally be expressed as the sum of two components: the co-ion component, zetaco-ion, and the counterion component, zetacounterion (where zeta = zetaco-ion + zetacounterion) and that the limiting electrophoretic mobility mu(infinity) is given by mu(infinity) = epsilonr epsilon0 zetaco-ion(infinity)/eta + 0(1/ka), where zetaco-ion(infinity) is the high zeta-limiting form of zetaco-ion, epsilonr and eta are, respectively, the relative permittivity and viscosity of the solution, and epsilon0 is the permittivity of a vacuum. That is, the particle behaves as if its zeta potential were zetaco-ion(infinity), independent of zeta. For the case of a positively charged particle in an aqueous electrolyte solution at 25 degrees C, the value of zetaco-ion(infinity) is 35.6 mV for 1-1 electrolytes, 46.0 mV for 2-1 electrolytes, and 12.2 mV for 1-2 electrolytes. It is also found that the magnitude of mu(infinity) increases as the valence of co-ions increases, whereas the magnitude of mu(infinity) decreases as the valence of counterions increases.

Journal Article↗

PubMed2006

Temperature and concentration effects on electrolyte transport across porous thin-film composite nanofiltration membranes: Pore transport mechanisms and energetics of permeation.

The influence of temperature and concentration on nanofilter charge density and electrolyte pore transport mechanisms is reported. Crossflow filtration experiments were performed to measure transport of several electrolytes (NaCl, NaNO3, NaClO4, CaCl2, MgCl2, and MgSO4) across two commercially available thin-film composite nanofiltration membranes in the range 5-41 degrees C. Experiments were also performed with selected salts in the range 1-50 meq/L to quantify concentration effects. Three different approaches, irreversible thermodynamics, extended Nernst-Planck formulation, and theory of rate processes, were employed to interpret retentions of these symmetric and asymmetric electrolytes at varying temperature and concentration. Increasing feed water temperature slightly increased electrolyte reflection coefficients and only weakly increased permeability compared with neutral solutes. Electromigration and convection tended to counteract each other at high fluxes explaining the weak temperature dependence of the reflection coefficient. Changes in membrane surface charge density with temperature were attributed to increased adsorption of electrolytes on the polymer constituting the active layer. Activation energy of permeation for charged solutes was primarily determined by the Donnan potential at the membrane-feed water interface. Electrolyte permeation was shown to be an enthalpy-driven process that resulted in small entropy changes. Increasing sorption capacity with temperature and low sorption energies indicated that co-ion sorption on polymeric membranes was an endothermic physicosorption process, which appears to determine temperature dependence of electrolyte permeation at increased feed concentrations.

Journal Article↗