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PubMed2003

Nonionic organic solute sorption onto two organobentonites as a function of organic-carbon content.

Sorption of three nonionic organic solutes (benzene, trichloroethene, and 1,2-dichlorobenzene) to hexadecyltrimethylammonium bentonite (HDTMA bentonite) and benzyltriethylammonium bentonite (BTEA bentonite) was measured as a function of total organic-carbon content at quaternary ammonium cation loadings ranging from 30 to 100% of the clay's cation-exchange capacity. Sorption of all three solutes to HDTMA bentonite was linear and sorption of all three solutes by the HDTMA bentonite increased as the organic-carbon content of the clay increased. 1,2-Dichlorobenzene sorbed most strongly to HDTMA bentonite, followed by benzene and TCE. The stronger sorption of benzene to HDTMA bentonite compared to TCE was unexpected based on a partition mechanism of sorption and consideration of solute solubility. LogK(oc) values for all three solutes increased with organic-carbon content. This suggests that the increased organic-carbon content alone may not explain the observed increase in sorption capacity. Sorption of the three solutes to BTEA bentonite was nonlinear and solute sorption increased with decreasing organic-carbon content, with a peak in the magnitude of solute sorption occurring at an organic-carbon content corresponding to 50% of CEC. Below 50% of CEC, sorption of all three solutes to BTEA bentonite decreased with decreasing organic-carbon content. Surface area measurements indicate that the surface area of both organobentonites generally decreased with increasing organic-carbon content. Since nonionic organic solute sorption to BTEA bentonite occurs by adsorption, the reduced sorption is likely caused by the reduction in surface area corresponding to increased organic-cation loading.

Journal Article↗
PubMed2003

Decomposition of hydroxylamine/water solution with added iron ion.

Decomposition hazards of hydroxylamine (HA)/water solution with and without the addition of iron ion were studied in this paper. Tests were conducted to obtain information about decomposition hazards of HA/water solution following the United Nations recommendations on the transport of dangerous goods. When the heat accumulation storage test was conducted using HA50 wt.%/water solution without the addition of iron ion, the self-accelerating decomposition temperature (SADT) was 80 degrees C. Therefore, HA50 wt.%/water solution was not classified with self-reactive substances following the United Nations recommendations on the transport of dangerous goods. Decomposition hazards of HA50 wt.%/water solution with added iron ion were investigated. The concentration of iron ion in sample of HA50 wt.%/water solution without the addition of iron ion was below 1.0 ppm. The range of the concentration of iron ion in sample of HA50 wt.%/water solution with added iron ion was between 1.0 and 5.4 ppm. The thermal stability of HA50 wt.%/water solution decreased by the addition of iron ion in the heat accumulation storage test. HA50 wt.%/water solution with the addition of iron ion was classified with self-reactive substances following the United Nations recommendations on the transport of dangerous goods. The intensity of the thermal decomposition of HA50 wt.%/water solution increased by the addition of iron ion in the Koenen test.

Accidents↗
PubMed2000

QSRR prediction of chromatographic retention of ethynyl-substituted PAH from semiempirically computed solute descriptors.

Retention prediction of 12 ethynyl-substituted polycyclic aromatic hydrocarbons (PAH) and their six unsubstituted parent compounds has been elucidated by the application of quantitative structure-retention relationship (QSRR) analysis. Retention data of the PAH were obtained from reversed-phase high-pressure liquid chromatography (HPLC) utilizing an octadecylsilica stationary phase operated under linear-gradient elution (60:40 water/acetonitrile to pure acetonitrile in 40 min). Six solute descriptors (moment of inertia, total energy, polarizability, ionization potential, dipole moment, subpolarity), computed from the optimized semiempirical AM1, MNDO, and PM3 solute geometries, were examined. Results from one-parameter QSRR analysis showed that retention of solutes was best predicted with solute polarizability as the parameter, computed from the AM1-(r = 0.969), MNDO-(r = 0.970), or PM3 (r = 0.967)-optimized solute geometries. From two-parameter QSRR analysis involving a size-specific parameter accompanied by a polarity parameter, it was found that solute retention was best reproduced by using solute polarizability and subpolarity as the parameters calculated from the AM1-(r = 0.983), MNDO-(r = 0.983), or PM3 (r = 0.984)-optimized solute geometries. On the basis of the results from both one-parameter and two-parameter regression analysis, the two-parameter QSRR equation with polarizability and subpolarity as parameters was found to be the best relation in relating solute molecular structure to retention under the HPLC conditions investigated. The results obtained in this study are of significance to predicting the identify of unknown product components based solely on parameters derived from solute structure.

Alkynes↗
PubMed2005

Solutes probe hydration in specific association of cyclodextrin and adamantane.

Using microcalorimetry, we follow changes in the association free energy of beta-cyclodextrin (CD) with the hydrophobic part of adamantane carboxylate (AD) due to added salt or polar (net-neutral) solutes that are excluded from the molecular interacting surfaces. Changes in binding constants with solution osmotic pressure (water activity) translate into changes in the preferential hydration upon complex formation. We find that these changes correspond to a release of 15-25 solute-excluding waters upon CD/AD association. Reflecting the preferential interaction of solute with reactants versus products, we find that changes in hydration depend on the type of solute used. All solutes used here result in a large change in the enthalpy of the CD-AD binding reaction. In one class of solutes, the corresponding entropy change is much smaller, while in the other class, the entropy change almost fully compensates the solute-specific enthalpy. For many of the solutes, the number of waters released correlates well with their effect on air-water surface tensions. We corroborate these results using vapor pressure osmometry to probe individually the hydration of reactants and products of association, and we discuss the possible interactions and forces between cosolute and hydrophobic surfaces responsible for different kinds of solute exclusion.

Adamantane↗
PubMed2005

Simultaneous release of hydrophobic and cationic solutes from thin-film "plum-pudding" gels: a multifunctional platform for surface drug delivery?

The release of two compositionally different solutes from a composite gel composed of two different populations of microgel particles embedded in a single bulk gel matrix is described, showing the potential of the "plum-pudding gel" as a multifunctional platform for controlled surface release. One hydrophobic solute (pyrene) and one hydrophobic and charged solute (rhodamine 123) were chosen as the solutes to be released. Hydrophobic microgels composed of 50% N-isopropylacrylamide (NIPAM) and 50% N-tert-butylacrylamide (BAM) were loaded with pyrene, and anionic microgels composed of 30% acrylic acid (AAc), 20% NIPAM, and 50% BAM were loaded with rhodamine 123. The two solute-loaded microgel populations were incorporated into a single bulk gel network, from which the two solutes were released simultaneously and independently. Using this structural motif, solutes that are mutually incompatible can be incorporated into a single matrix with which they may also be incompatible. The electrostatically incorporated solute was released much more slowly than the hydrophobically attracted solute, indicating that the microgel composition can be tailored to the specific solute, and thus control its release rate. The choice of bulk matrix was also found to influence the release rate much more than expected, offering a further control element to the system.

Drug Delivery Systems↗
PubMed1997

Polar solute transport across the pigmented rabbit conjunctiva: size dependence and the influence of 8-bromo cyclic adenosine monophosphate.

PURPOSE: To characterize the conjunctival permeability to polar solutes ranging from 182 to 167,000 daltons in molecular weight (m.w.). METHODS: Solute transport across the excised pigmented rabbit conjunctiva with a baseline transepithelial electrical resistance (TEER) of 1,285 +/- 46 ohm.cm2 was evaluated in the modified Ussing chamber under open-circuit conditions. The model solutes were mannitol (m.w. 182), 6-carboxyfluorescein (m.w. 376), and fluorescein isothiocyanate-labeled dextrans (FD4, m.w. 4,400-FD150, m.w. 167,000). RESULTS: For a given solute, the apparent permeability coefficient (Papp) was independent of solute concentration and direction of transport. As expected, the Papp decreased with solute size, from 27.7 x 10(-8) cm/sec for mannitol to 0.31 x 10(-8) cm/sec for FD150. When the experimental temperature was lowered from 37 degrees C to 4 degrees C. Papp decreased by approximately 50% for FD4 through FD40 and by > 80% for both FD70 and FD150. Equivalent pore analysis, assuming restricted solute diffusion via cylindrical, water-filled pores across the isolated tissue, revealed a radius of 5.5 nm at a pore density of 1.9 x 10(8) pores per cm2. The addition of 1 mM 8-bromo cyclic adenosine monophosphate (8-BrcAMP), known to stimulate Cl- secretion and decrease TEER, to the mucosal side of the conjunctiva increased the transport of mannitol, FD4, and FD40 by 28%, while not affecting FD150 transport. CONCLUSIONS: Our findings suggest that polar solutes up to FD40 traverse the conjunctival epithelial barrier primarily by restricted diffusion through equivalent pores of 5.5 nm radius and that solute movement is affected by reduction of TEER. On the other hand, polar solutes of the FD70 or larger may cross the barrier primarily via non-diffusional pathways such as non-specific endocytosis.

Animals↗
PubMed1988

The role of protein and lipid domains in the uptake of solutes by human stratum corneum.

The uptake of a series of hydrocortisone esters varying in lipophilicity from water into untreated and delipidized human stratum corneum has been determined. The partition coefficients of solutes into fully hydrated stratum corneum are postulated to represent the separate contributions of three structurally distinct domains--the extractable lipids, protein, and the solvent domain. The solvent domain was assumed to have the properties of bulk water. The relative affinities of the protein and lipid domains of stratum corneum for solutes varying in structure were determined by comparing solute uptake in untreated and delipidized stratum corneum. Partitioning into the extracted lipids was also examined. Solute uptake into stratum corneum may be governed by the protein domain, the lipid domain, or a combination of the two, depending on solute lipophilicity. Due to differences in the selectivity of the two domains, a change in uptake mechanism occurs with increasing solute lipophilicity from protein-dominated uptake for hydrophilic solutes to lipid domain-dominated uptake for lipophilic solutes. The stratum corneum lipid content, which varies dramatically from individual to individual (3-46% in this study), is an important determinant of the affinity of the stratum corneum for highly lipophilic solutes but has no effect on the uptake of hydrophilic solutes.

Chromatography, Liquid↗
PubMed1991

Visceral peritoneum is not essential for solute transport during peritoneal dialysis.

The importance of visceral peritoneum in determining transperitoneal solute exchange was studied by determining the influence of evisceration on diffusive solute transport during peritoneal dialysis. Three series of experiments were performed in anesthetized New Zealand White rabbits. Series 1 studies compared solute transport rates from eviscerated rabbits (N = 5) with those from sham-operated controls (N = 5). Series 2 studies compared solute transport rates from eviscerated (N = 6) and sham-operated rabbits (N = 5) with application of circumferential abdominal compression to control intraperitoneal pressure and presumably maximize dialysate-peritoneum contact. Series 3 studies compared solute transport rates from sham-operated rabbits (N = 4) with and without applied circumferential abdominal compression. Transperitoneal solute exchange of creatinine and FITC-labeled neutral dextran (15 to 40 A) was equally assessed by both the dialysate to plasma concentration ratio at the end of the exchange and the diffusive permeability-area product of the peritoneum. Evisceration reduced creatinine (P less than 0.001) and dextran (15 to 30 A, P less than 0.05) transport to approximately one quarter that of controls in series 1 rabbits. When circumferential abdominal compression was applied in series 2 rabbits, however, evisceration had no effect on peritoneal solute transport rates. Moreover, circumferential abdominal compression per se had no effect on solute exchange in series 3 experiments. These findings demonstrate that the influence of evisceration on peritoneal solute transport depends on the experimental conditions. These observations further demonstrate that visceral peritoneum is not essential for solute transport during peritoneal dialysis.

Animals↗
PubMed2004

Tolerance of an enterally administered simulated amniotic fluid-like solution by neonates recovering from surgery for congenital bowel abnormalities.

OBJECTIVE: We report a single-centered, Phase I pilot trial, testing the enteral administration of an experimental amniotic fluid-like solution to 10 neonates who were otherwise "NPO" following surgery for congenital bowel abnormalities. The overall hypothesis was that the trophic effect of the solution on intestinal villi would facilitate advancement to full enteral feedings. The specific hypothesis tested in this pilot trial was that the solution would be tolerated. STUDY DESIGN: Ten neonates who were NPO following surgery for congenital bowel abnormalities, were studied before any "trophic" feedings were begun. Each received an experimental, sterile, isotonic, amniotic fluid-like solution at a dose of 20 ml/kg/day enterally. When milk feedings were begun they were mixed with the experimental solution. Increases in the volume of milk feedings occurred at the discretion of the neonatologist and surgeon, and the experimental solution was discontinued any time the neonatologist or surgeon felt it was not tolerated, or when 100 ml of milk feedings/kg/day was achieved. We quantified the amount and character of emesis, stools, and gastric residuals, measured abdominal girth and blood pressure, looked for skin rashes, and sought any signs of intolerance or adverse events. We recorded the days to achieve milk feedings of 20, 50, 100, and 120 ml/kg/day and length of hospital stay. RESULTS: The experimental solution was begun 4 to 32 days after surgery, invariably prior to the institution of "trophic" milk feedings. All subjects completed the doses with no evidence of intolerance. All achieved 100 ml/kg of milk feedings 14 days, or fewer, following institution of the experimental solution (mean 11.1 days, range, 3 to 14). All lived and were discharged home 20.2 days (range, 8 to 42) after the experimental solution was begun. CONCLUSIONS: In this pilot trial involving 10 neonates who had surgery for congenital bowel abnormalities, the enteral administration of a sterile, isotonic, amniotic fluid-like solution was tolerated.

Drug Combinations↗
PubMed2003

Differences in electrophysiological and contractile properties of mammalian cardiac tissues bathed in bicarbonate - and HEPES-buffered solutions.

AIM: The aim of this study was to compare the action potential configuration, contractility, intracellular Ca2+ and H+ concentrations in mammalian cardiac tissues bathed with Krebs and Tyrode solutions at 37 degrees C. RESULTS: In Langendorff-perfused guinea-pig hearts, loaded with the fluorescent Ca2+-indicator Fura-2, or H+-sensitive dye carboxy-SNARF, shifts from Krebs to Tyrode solution caused intra-cellular acidification, increased diastolic pressure and [Ca2+]i, decreased systolic pressure and [Ca2+]i, leading to a reduction in the amplitude of [Ca2+]i transients and pulse pressure. Contractility was also depressed in canine ventricular trabeculae when transferred from Krebs to Tyrode solution. Shifts from Krebs to Tyrode solution increased the duration of action potentials in multicellular cardiac preparations excised from canine and rabbit hearts but not in isolated cardiomyocytes. All these changes in action potential morphology, contractility, [Ca2+]i and [H+]i were readily reversible by addition of 26 mmol L(-1) bicarbonate to Tyrode solution. Effects of dofetilide and CsCl, both blockers of the delayed rectifier K current, on action potential duration were compared in Krebs and Tyrode solutions. Dofetilide lengthened rabbit ventricular action potentials in a significantly greater extent in Tyrode than in Krebs solution. Exposure of canine Purkinje fibres to CsCl evoked early after depolarizations within 40 min in all preparations incubated with Tyrode solution, but not in those bathed with Krebs solution. CONCLUSION: It is concluded that the marked differences in action potential morphology, [Ca2+]i, [H+]i and contractility observed between preparations bathed with Krebs and Tyrode solutions are more likely attributable to differences in the intracellular buffering capacities of the two media.

Action Potentials↗
PubMed2000

A linear regression model to predict the pH of neonatal parenteral nutrition solution.

INTRODUCTION: Providing the high calcium intake necessary for normal bone mineralization in rapidly growing very low birth weight infants is difficult because calcium and phosphorus solubility is limited in the range of parenteral nutrition pH. A major determinant of calcium and phosphorus solubility in vitro is solution pH. The objective of this study was to develop and assess the accuracy of a method to predict the final parenteral solution pH as a linear function of the individual parenteral component concentrations. METHODS: pH values were measured for 205 neonatal parenteral nutrition solutions prepared during a 5-week period. Concentrations of the 13 components used to synthesize parenteral nutrition were determined for each solution. Data from 135 samples were used to develop a linear regression coefficient model with pH as the dependent variable. From the regression model the pH was predicted for the remaining 70 samples using the seven significant solution component concentrations, and the predicted and measured solution pH values were compared. RESULTS: The mean measured parenteral nutrition pH for all solutions was 5.364 +/- 0.110 (mean +/- SD, range 5.03-5.73). The absolute mean pH difference between the predicted and measured value for the 70 test samples was 0.04 +/- 0.04. pH estimated with the model correlated highly with measured pH (r2 = 0.77). The seven components in the regression model accounted for 81% of the pH variance. CONCLUSION: The pH of neonatal parenteral nutrition solutions can be predicted accurately as a linear function of the solution concentrations of the following seven components: sodium acetate, sodium phosphate, potassium phosphate, potassium acetate, magnesium sulphate, amino acid solution and dextrose. The absolute mean difference between measured pH and predicted pH was 0.04. Applying this method to estimate pH with the interactive properties of computer-based ordering systems could enhance calcium and phosphorus administration to very low birth weight infants.

Calcification, Physiologic↗
PubMed2000

The use of electrolyzed solutions for the cleaning and disinfecting of dialyzers.

Recently, the use of electrolyzed solutions has attracted considerable interest in Japan. This study investigates the efficiency of electrolyzed solutions as disinfecting agents (DA) in the reuse of dialyzers and compares their efficiency to that of other disinfectants currently in use. The following 3 methods were employed. First, the rinsing time and rebound release of reused dialyzers were measured and compared after electrolyzed solutions, electrolyzed strong acid aqueous solution (ESAAS) and electrolyzed strong basic aqueous solution (ESBAS), made from reverse osmosis (RO) water (ESAAS, ESBAS; Generating apparatuses: Super Oxseed alpha 1000, Amano Corporation, Yokohama, Japan), 2% Dialox-cj (Teijin Gambro Medical, Tokyo, Japan), and 3.8% formalin were used as DAs. This involved performing dialysis with 2 types of dialyzers: a cellulose acetate membrane (CAM) dialyzer and a polysulfone membrane (PSM) dialyzer. The dialyzers were cleaned and disinfected using the different DA and left for 48 h. Next, after performing dialysis the dialyzer membranes were cleaned with a saline solution (0.9% NaCl) and RO water and then cleaned with the various DA. These membranes were observed using a scanning electron microscope (SEM) to check for the presence of physical and biological contaminants. Finally, in vitro tests were performed to determine the level of dialyzer clearance when PSM dialyzers were reused after having been cleaned and disinfected with the electrolyzed solutions. The rinsing time results for both the CAM and PSM dialyzers showed the electrolyzed solutions (ESBAS and ESAAS) as being undetectable within 10 min. With regard to the rebound release, for both the CAM and PSM dialyzers, the electrolyzed solutions were undetectable at all checking times between 30 and 240 min. Observation by SEM showed that cleaning with both ESAAS and ESBAS left the fewest contaminants, and cleaning with 2% Dialox-cj left the highest level of contaminants in the CAM dialyzers. With regard to experiments concerning use in vitro, no major changes in the dialyzer clearance were noticed after 6 uses. In every experiment, the previous investigations showed the electrolyzed solutions to be superior to 3. 8% formalin and 2% Dialox-cj DA for the reuse of dialyzers.

Acids↗
PubMed1985

Steroids and cardioplegia. An experimental evaluation of glucocorticoid supplementation to cardioplegic solutions in clinical use.

The influence of glucocorticoid supplementation to cardioplegic solutions is still open to debate. The isolated working rat heart model was used to test the efficacy of glucocorticoid (methylprednisolone sodium succinate (MPSS] supplementation to 2 clinical cardioplegic solutions. Hearts were subjected to either 80 minutes or 120 minutes of hypothermic (18.5 degrees C) global ischemia after single-dose administration (4 degrees C) of one of the cardioplegic solutions A ("Hamburg" solution) or B (simple potassium-based solution). Each cardioplegic solution was infused containing either MPSS in the clinically used concentration (250 mg/l or 500 mg/l for solution A and B, respectively) or without MPSS. The recovery of aortic flow, coronary flow, peak aortic pressure and heart rate was compared with preischemic control values. Creatine kinase (CK) release was measured in the early reperfusion period and the myocardial content of ATP was measured at 30 minutes of reperfusion. Solution B provided only a moderate protection against ischemic damage. Inclusion of MPSS 500 mg/l slightly improved the recovery of physiological indices, reduced CK leakage and increased myocardial ATP. Solution A provided a more effective protection against ischemia. The addition of MPSS in this situation did not affect the overall postischemic recovery. We suggest that the addition of MPSS may improve the protective properties of a cardioplegic solution when the ischemic injury is rather severe.

Adenosine Triphosphate↗
PubMed2005

Sub-Tg relaxations due to dipolar solutes in nonpolar glass-forming solvents.

It is well known that rigid dipolar solutes (in smaller quantity) dispersed in a nonpolar glassy matrix exhibit a sub-T(g) (or beta(s)) relaxation due to the solute often designated as Johari-Goldstein (JG) relaxation, which is intermolecular in nature. In this article, we report the results of our study of such a sub-T(g) process in a wide variety of dipolar solutes in different glassy systems using dielectric spectroscopy over a frequency range of 20-10(6) Hz down to a temperature of 77 K. The T(g) of these solutions are determined using differential scanning calorimetry. The solvents used in this study are o-terphenyl (OTP), isopropylbenzene (IPB), and methylcyclohexane. In the case of rigid molecular solutes, like mono-halogen benzenes, the activation energy (DeltaE(beta)) of the beta(s) process is found to increase with decreasing T(g) of the solvent, with a corresponding decrease in the magnitude of the beta(s) process. In the case of more symmetrical molecular solute, for example, tert-butylchloride, the change in DeltaE(beta) is not very appreciable. These results emphasize the importance of the size of the cage of the host matrix in the relaxation of the solute molecules. We have also studied the sub-T(g) relaxation(s) due to some flexible molecular solutes, viz., 1butylbromide, 1hexylbromide, 1butylacetate, and benzylacetate. These solutes in IPB matrix exhibit only one relaxation, whereas in OTP matrix they exhibit an additional sub-T(g) process, which may be identified with a JG type of relaxation. These observations lead us to the conclusion that the beta process observed in the glassy states of these pure solutes is predominantly intramolecular in nature.

Journal Article↗
PubMed2006

Molecular dynamics and interactions of aqueous and dichloromethane solutions of polyvinylpyrrolidone.

We have investigated the dynamics of polyvinylpyrrolidone solutions (PVP, M(w)=10 000) on time scales from 20 fs to 42 ps using femtosecond optically heterodyne-detected Raman-induced Kerr effect spectroscopy. To compare the dynamics of polymer solutions with those of the analogous monomer, we also characterized solutions of 1-ethyl-2-pyrrolidone (EP). Dynamics of both PVP and EP solutions have been characterized for sample concentrations of 6.4, 12.7, 24.5, 33.3, and 40.7 wt %. The longest time scale relaxations observed in the Kerr transients for these solutions occur on the picosecond time scale and are best fit to triexponential functions. The intermediate and slow relaxation time constants for PVP and EP solutions are concentration dependent. The time constants for the PVP solutions are not consistent with the predictions of hydrodynamic models, while the analogous time constants for the EP solutions do display hydrodynamic scaling. The predominant relaxation of the polymer is assigned to reorientations of the pyrrolidone side group or torsional motions of the constitutional repeat unit, with additional relaxation pathways including hydrogen bond reorganization in aqueous solution and segmental motion of multiple repeat units. The vibrational dynamics of PVP and EP solutions occur on the femtosecond time scale. These dynamics are analyzed with a focus on the additional degrees of freedom experienced by EP relative to PVP that result from the absence of the tether from the pyrrolidone group on the main chain backbone. The intermolecular Kerr spectra of PVP in H(2)O and CH(2)Cl(2) differ because H(2)O can donate a hydrogen bond to the carbonyl acceptor group on the pyrrolidone ring, while CH(2)Cl(2) cannot.

Journal Article↗
PubMed1987

Zinc absorption from glucose and amino acid dialysis solutions in children on continuous ambulatory peritoneal dialysis (CAPD).

Zinc deficiency in children with chronic renal failure may be due to inadequate intake or excessive losses. To determine the effect of dialysate solute type and concentration on the net absorption or loss of zinc from the peritoneal cavity, six CAPD patients ages 9-19 years were dialyzed with 1.3% and 2.3% amino acid-containing dialysis solutions and 2.5% and 4.25% glucose-containing solutions on four separate occasions. Zinc contamination of the initial effluent dialysis solutions was quite high (17.1 +/- 7.7 micrograms/dl) but did not differ between the four solutions. Significantly higher zinc retention was documented with the glucose-containing dialysis solutions compared to the amino acid-containing solutions (99.8 +/- 32.7 vs. 28.3 +/- 51.3 micrograms, 2.5% G vs 1.3% AA, p less than 0.01; 146.0 +/- 112.6 vs. 23.0 +/- 84.3, 4.25% G vs 2.3% AA, p less than .01). Although the mechanism is unclear, results of this study confirm in children that there is significant net absorption of zinc from glucose containing dialysis solutions at both high and low glucose concentrations. Thus, CAPD does not contribute to zinc depletion. Solute concentration did not affect net zinc absorption; thus it appears that movement of zinc across the peritoneum is dependent on solute type (amino acid or glucose) and independent of the osmolality.

Absorption↗
PubMed1971

Theoretical analysis of net tracer flux due to volume circulation in a membrane with pores of different sizes. Relation to solute drag model.

When osmotic pressure across an artificial membrane, produced by a permeable electrically neutral solute on one side of it, is balanced by an external pressure difference so that there is no net volume flow across the membrane, it has been found that there will be a net flux of a second electrically neutral tracer solute, present at equal concentrations on either side of the membrane, in the direction that the "osmotic" solute diffuses. This has been ascribed to solute-solute interaction or drag between the tracer and the osmotic solutes. An alternative model, presented here, considers the membrane to have pores of different sizes. Under general assumptions, this "heteroporous" model will account for both the direction of net tracer flux and the observed linear dependence of unidirectional tracer fluxes on the concentration of the osmotic solute. The expressions for the fluxes of solutes and solvent are mathematically identical under the two models. An inequality is derived which must be valid if the solute interaction model and/or the heteroporous model can account for the data. If the inequality does not hold, then the heteroporous model alone cannot explain the data. It was found that the inequality holds for most published observations except when dextran is the osmotic solute.

Cell Membrane Permeability↗
PubMed2003

Solbase: a databank of solutions for occupational hazards and risks.

Several attempts have been made to develop strategies for an effective control of workplace hazards. This paper will focus on the results of a European project called Solbase, which is a databank for solutions to occupational hazards and risks. The Safety Science Group of Delft University of Technology in collaboration with TNO Work and Organisation (formerly NIA-TNO) designed Solbase in a series of projects funded by the Dutch Ministry of Social Affairs and Employment and the European Commission. It consists of the design of and software for a databank with an intelligent navigation system allowing users two principal entry points, which correspond to two basic types of solutions. The first entry point is based on the production process, subdivided into the production principle and production function. This entry point provides the dissemination of solutions within and between branches of industry. The second entry point includes the hazard and its emission and transmission as an access point for more conventional occupational hygiene control measures. With the partners of the consortium, from Spain, Italy, Ireland, Germany, the UK and The Netherlands, 535 new and existing solutions throughout Europe and the world were gathered to test the software and the solutions during a field study. Despite the relatively small number of 'test solutions' used, 54% of the search actions in the field study resulted in a useful and suitable solution which the company could actually put into practice. The companies characterized the software as very user friendly. The reproducibility of the coding system for solutions, the classification tree, was satisfactory. Most coders chose the same keywords from the classification tree to describe a corresponding solution. Solbase is a good searching machine for workplace solutions. Especially, the classification of production processes is an inherent guarantee of an exchange of information across the borders of a specific company or branch of industry.

Databases, Factual↗