Organic Salt Solutions Research Articles

Swelling of the collagen-keratocytematrix of the bovine corneal stroma ex vivo in various solutions and its relationship to tissue thickness

Aim: The mammalian corneal stroma, like some other connective tissues, can absorb fluid, swell and become oedematous. Since studies on the corneal stroma have been carried out with different types of preparations and solutions, inter-study comparisons are very difficult. A study was thus undertaken on a standardised preparation to assess the relative magnitude of this swelling and its relationship to thickness of the preparations. Methods: From selected recent post-morterm eyes of adult cattle, stroma preparations were cut from the central part of the cornea. These preparations were immersed in various solutions of known pH and osmolality, and the time-dependent changes in wet mass were assessed over 9 h at 37°C. The relative rates and magnitude of the swelling of the tissue were then compared. Results: A reference value for stromal swelling was obtained by incubation in a 35 mMbicarbonate-buffered mixed salts solution equilibrated with 5% CO 2-air (pH 7.60) where a 3.39-fold increase in wet mass and a 4.58-fold increase in thickness was realised in 9h, at an initial rate of 76±3%/h. The swelling was essentially the same in an organic buffer-mixed salt solution (pH 7.5) but progressively greater in phosphate-buffered saline (pH 7.5), a range of phosphate buffers (10–67 mM, pH 7.5), NaCl solutions (0.025–1%) and with gross swelling observed in water (where a 15.9-fold increase in wet mass occurred along with a 25-fold increase in thickness, at an initial rate of 643±62%/h). Overall, the wet mass changes were strongly related to thickness ( P< 0.001). Conclusions: The results confirm that the selection of solution(s) for studies on corneal stromal swelling is critical. The swelling (oedema) is lower in a physiologically-relevant solution (similar to the aqueous humour of the eye). This indicates that the swelling tendency of the corneal stroma has been overestimated in the past, and that a similar discrepancy may also exist for studies on other connective tissues ex vivo when non-physiological experimental solutions are used.

Application of Organic and Inorganic Salts to Field-Grown Potato Tubers Can Suppress Silver Scurf During Potato Storage.

Silver scurf, caused by Helminthosporium solani, is an economically important postharvest disease of potato tubers. Organic and inorganic salts were evaluated for their ability to suppress silver scurf lesion development and sporulation of H. solani on potato tubers. Tubers were treated immediately after harvest with 0.2-M solutions of potassium sorbate, calcium propionate, sodium bicarbonate, sodium carbonate, ammonium bicarbonate, or water. Tween 20 was added as a surfactant to most treatments. Potassium sorbate (0.1 M), acidified potassium sorbate and calcium propionate treatments (0.2 M), and calcium chloride treatments (0.136 M) were included in additional experiments. Tubers were stored under commercial storage conditions for 4 to 6 months prior to disease evaluation. The extent of disease suppression varied among experiments; however, some treatments consistently reduced disease. Lesion formation on the tuber surface was reduced by 26 to 60% using potassium sorbate (in three of four experiments) compared to water-treated or untreated tubers. Sporulation was suppressed by 0.2 M potassium sorbate (78 to 99% reduction) in all four experiments. Sodium carbonate reduced lesion formation in two experiments and sporulation in three of four experiments. Other treatments inconsistently suppressed lesion formation or sporulation, or did not reduce disease. Addition of Tween or acidification of organic salt solutions did not improve silver scurf suppression in most cases. Potassium sorbate has very low mammalian toxicity and great potential as an innocuous and inexpensive postharvest fungicide for suppression of silver scurf during potato storage.

Sorption of Benzene, Toluene, Ethylbenzene, and Xylene (BTEX) Compounds by Hectorite Clays Exchanged with Aromatic Organic Cations

AbstractAdsorptive-type organoclays, where hydrocarbons adsorb directly to the siloxane surfaces, were studied to find new organic cations and to determine the parameters that produce effective sorbents. Organoclays were prepared from hectorite by cation exchange with small, aromatic organic cation salt solutions. Trimefhylphenylammonium (TMPA) chloride was obtained and iodide salts of commercially-unavailable aromatic cations were synthesized and used to prepare organoclays. An aqueous mixture of benzene, toluene, ethylbenzene, and xylenes (BTEX) consistent with the composition of unleaded gasoline was used in sorption isotherms to compare the sorptive properties of the organoclays. Only the TMPA, methylphenylpyridinium (MPPyr), and trimethylammonium indan (Indan) organoclays were effective BTEX sorbents. Organoclays prepared from methylpyridinium (MPyr), trimethylammonium biphenyl (Biphenyl), and trimethylammonium fluorene (Fluorene) were poor sorbents. The MPPyr and TMPA organoclays preferentially sorbed ethylbenzene, whereas the Indan organoclay preferentially sorbed benzene and toluene. Langmuir-type sorption isotherms for the TMPA, MPPyr, and Indan organoclays implied surface adsorption, whereas linear isotherms suggested that partitioning was the sorptive mechanism for the MPyr, Biphenyl, and Fluorene organoclays. Water hydrating the small MPyr cation and the larger bulk of the Biphenyl and Fluorene cations may have blocked BTEX access to the interlayer siloxane surfaces. Although the rather bulky MPPyr and Indan cations produced effective organoclays, compact size and low hydration are organic cation properties that typically yield effective adsorptive-type organoclays.

Evidences for the presence of aluminium perrhenate at the surface of Re 2O 7/Al 2O 3 metathesis catalysts

The nature of the rhenium species present in the Re 2O 7/Al 2O 3 metathesis catalysts was investigated by chemical extraction and leaching using various organic salt solutions and water. By means of organic salt solutions, rhenium is extracted as perrhenate salts, and by means of water, rhenium and aluminium are extracted together with a (Re/Al) molar ratio of 3. This result is a first indication for the presence of Al(ReO 4) 3 (or a decomposition product of Al(ReO 4) 3) in Re 2O 7/Al 2O 3 catalysts. Furthermore, using IR spectroscopy, we pointed out a ≈1320 cm −1 band characteristic of ammonia coordinated on aluminium perrhenate which corroborates our results. We showed that aluminium perrhenate mixed with silica is active in the metathesis reaction.

Passivation kinetics of surface films formed on a graphite electrode in organic lithium salt solution as a function of salt anion type

The passivation kinetics of a graphite electrode have been investigated as functions of applied potential and salt anion type by using cyclic voltammetry and current transient experiments supplemented with ac-impedance spectroscopy. The cyclic voltammogram and current transient were obtained after abrading the graphite bulk electrode subjected to various negative potentials with respect to the open circuit potential of about 3.0 V (Li|Li+) in 1 M LiAsF6, LiPF6 and LiN(SO2CF3)2+ ethylene carbonate (EC) + diethyl carbo (DEC) solutions. The current transients illustrated the passivation kinetics which can be split into two steps of prepassivation and passivation. The LiAsF6 salt gave a reduced reduction current in the second cycle of the voltammogram, the steeper slope of the current transient and the lowered ratios of Rporous to Rcompact and of Ccompact to Cporous obtained from the measured impedance spectra as compared to LiPF6 and LiN(SO2CF3)2 salts. The three factors are characterized by the improved passivity of the surface film formed in LiAsF6 + EC + DEC solution. The passivity of the surface film on the graphite electrode has been discussed in terms of the reactivity of the salt anion towards reduction at the electrode.

Effect of removal of free oxides on changes in dispersibility and charge characteristics of soils

Abstract Changes in dispersibility and charge characteristics of two soils with different colloidal properties were investigated after various extracting treatments of free oxides. The soil samples were taken from the upland field in a reclaimed area (highly dispersive) and from the B horizon of an adjacent forest area (physically stable), both of which derived from the same parent material. Special attention was paid to selective extraction of Al and Fe oxides. After the extraction of free oxides by conventional methods such as DCB or oxalate treatment, dispersibility of the soils which always became too high made it difficult to relate the amounts of removed oxides with the changes in dispersibility. Thus, extractions by milder treatments were designed in order to remove varying amounts of free oxides using several organic salt solutions. Among the treatments, citrate and oxalate extracted more Al oxides, followed by tartrate. Dithionite, acetate, and NaCl extracted only trace amounts of Al oxides. This...

Relationship between solution shear viscosity and density at the saturation point

Properties of supersaturated solutions such as the density, viscosity, and solute diffusivity are dependent on the solute concentration. The diffusion-boundary-layer equations are derived and solved for the natural convection case with the viscosity and density dependent on the solute concentration. The solution obtained demonstrates that, at the vicinity of the saturation concentration cs, there is a non-trivial dependence of the solution viscosity η on its density ρ:η(cs) = η(ρs)αρ12s, where ρs = ρ(cs). This result has been verified in experiments with aqueous solutions of inorganic and organic salts.

Hydrothermal single crystal growth of calcite in ammonium acetate solution

Calcite single crystals were successfully grown in newly discovered ammonium acetate solution, an organic salt solution, under mild hydrothermal conditions below 250°C at saturated vapor pressure. The growth rate increased with the increase in growth temperature, temperature difference, and concentration of ammonium acetate solution. Even in a dilute ammonium acetate solution of 0.07M with a pH of 7.0, the seed crystal grew at a growth rate of 57 μm/day at 235°C with a temperature difference of 15°C. The grown crystal under these conditions was optically transparent and not contaminated with the mineralizer. Ammonium acetate solution has a large difference as a mineralizer for crystal growth of calcite from other inorganic salt solutions; In ammonium acetate solution, new planes, the f and a planes, developed on the seed crystal bound by the r planes.

Concentration dependence of solution shear viscosity and solute mass diffusivity in crystal growth from solutions.

The physical properties of a supersaturated binary solution such as its density \ensuremath{\rho}, shear viscosity \ensuremath{\eta}, and solute mass diffusivity D are dependent on the solute concentration c: \ensuremath{\rho}=\ensuremath{\rho}(c), \ensuremath{\eta}=\ensuremath{\eta}(c), and D=D(c). The diffusion boundary layer equations related to crystal growth from solution are derived for the case of natural convection with a solution density, a shear viscosity, and a solute diffusivity that are all dependent on solute concentration. The solution of these equations has demonstrated the following. (a) At the vicinity of the saturation concentration ${\mathit{c}}_{\mathit{s}}$ the solution shear viscosity \ensuremath{\eta} depends on \ensuremath{\rho} as ${\mathrm{\ensuremath{\eta}}}_{\mathit{s}}$=\ensuremath{\eta}(${\mathrm{\ensuremath{\rho}}}_{\mathit{s}}$)\ensuremath{\propto}${\mathrm{\ensuremath{\rho}}}^{1/2}$(${\mathit{c}}_{\mathit{s}}$). This theoretically derived result has been verified in experiments with several aqueous solutions of inorganic and organic salts. (b) The maximum solute mass transfer towards the growing crystal surface can be achieved for values of c where the ratio of d ln[D(c)/dc] to ln[\ensuremath{\eta}(c)/dc] is a maximum.

Halochromism and solvatochromism of a π* probe in binary solvent mixtures

Dipolarity polarizability values, π*, of 17 binary solvent mixtures of variable composition have been measured with the recently introduced probe 1. The values obtained are in good agreement with reported parameters derived previously for a few solvent mixtures, employing 4-nitroaniline and N,N-diethylnitroaniline as probes. Preferential solvation of dye 1 by the more polar component was observed for most binary mixtures. Exceptions to this behaviour were some alcoholic solvent mixtures, where 1 was preferentially solvated by the less polar alcohol. This departure from the generally observed trend was ascribed to the hydrophobic character of the bisthienyl dye. The halochromic behaviour of 1 in organic salt solutions was also investigated and rationalized in terms of dye–salt association.

Solubility and crystal growth of calcite in organic salt solutions under hydrothermal conditions

Solubility and crystal growth of calcite in organic salt solutions under hydrothermal conditions

ChemInform Abstract: Synthesis of Cuprates LnBa2Cu3O7‐x from Aqueous Solutions of Organic Amine Salts.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Achievement of renaturation of subtilisin BPN' by a novel procedure using organic salts and a digestible mutant of Streptomyces subtilisin inhibitor

The pro-sequences of proteases have been considered to be required for the refolding of denatured proteases. However, here we report achievement of almost complete restoration of enzymatic activity of subtilisin BPN' in the absence of its pro-sequence. The presence of 2 M potassium acetate in the folding medium enhanced the refolding efficiency of guanidine hydrochloride (GdnHCl)-denatured subtilisin BPN' by up to 28%, and other organic salts were also found to be useful, suggesting that general contribution of the bulky hydrophobic moieties of the salts to the formation of a favorable environment required for folding. This finding will provide new insights into the folding mechanisms not only of proteases but also of various other proteins. Almost complete restoration of enzymatic activity of denatured subtilisin in the organic salt solution was accomplished by further addition of mutated Streptomyces subtilisin inhibitor (SSI), which had been converted to a digestible temporary inhibitor by removal of the disulfide bridge near the reactive site.

The molecular mechanism for destabilization of foams by organic ions

AbstractThe effect of tetraalkylammonium ions on the destabilization of foam has been studied by measuring the half‐life of foam (τ1/2), area/molecule at the air/water interface, surface viscosity and critical micelle concentration (CMC) of sodium dodecyl sulfate (SDS). The area/molecule of SDS in organic salt solutions, calculated from the Gibbs isotherm, increases as the size of organic ion increases, and surface viscosity of the film decreases with the size of organic ions. The interaction of tetraalkylammonium ions with SDS decreases the CMC of the solution, and hence the concentration of SDS monomers decreases. The CMC of SDS decreases with the increase in the size and concentration of organic ions. The decrease in the CMC, increase in the area/molecule of SDS at the air/water interface and the decrease in surface viscosity by tetraalkylammonium ions all work to decrease the foam stability. The results indicate that the change in intermolecular distance between surfactant molecules in the adsorbed film by organic ions can significantly influence the surface viscosity and foam stability. The foam destabilizing efficiency of tetra‐alkylammonium ions was superior or equivalent to that of tributyl phosphate and 2‐ethyl hexanol, which are used in many antifoaming formulations.

Ultralow oil‐water IFTs using neutralized oxidized hydrocarbons as surfactants

Surfactants that may be suitable for application in enhanced oil recovery have been produced from C22 and C26 paraffinic and naphthenic petroleum fractions by a two‐step process. The hydrocarbon feed stocks were first oxidized in the vapor‐phase, followed by neutralization of the oxidized products with aqueous alkali. As a result, dilute solutions of organic acid salts were produced that achieved ultralow (&lt;10−2 dyne/cm) interfacial tensions against a synthetic oil. Surfactant solutions that exhibited the lowest interfacial tensions (IFTs) were prepared from neutralizations that used low concentrations of sodium hydroxide rather than sodium silicate, sodium tripolyphosphate, or sodium carbonate. Neutralizations that used sodium silicate or sodium carbonate resulted in surfactant solutions having IFT profiles that were less sensitive to the electrolyte concentration. When sodium hydroxide was combined with either sodium silicate or sodium tripolyphosphate in the neutralizations, solutions having intermediate IFT properties were produced. The amount of alkali used in the neutralizations was observed to affect the IFT properties of the resultant surfactant solution. The electrolyte concentration at which the minimum IFT occurred was inversely related to the pH of the surfactant solution. For surfactant solutions of common pH prepared from different concentrations of oxidized product, the minimum IFTs all occurred at the same concentration of electrolyte. Surfactant solutions remained interfacially active even in the presence of significant concentrations of calcium chloride. One pore volume of a solution containing only about 1% of active surfactant recovered 42.0% of the residual oil in a tertiary core‐flood experiment.

Inhibition of transport system b 0,+ in blastocysts by inorganic and organic cations yields insight into the structure of its amino acid receptor site

The most conspicuous, Na +-independent amino acid transport process in preimplantation mouse blastocysts was provisionally designated system b 0,+ because it accepts some cationic and zwitterionic amino acids about equally well as substrates. Although system b 0,+ is not Na +-stimulated, it has not been determined if it is inhibited by Na +, or if its activity is affected by most other ions. Therefore, we measured uptake of amino acids by blastocysts in isotonic solutions of different ionic and nonionic osmolites. Na +-independent l-leucine uptake was unaffected by the ion concentration, but l-lysine transport was several-fold faster in isotonic solutions of non-electrolytes than in similar solutions of inorganic and organic salts or zwitterions. The K m value for ‘Na +-independent’ l-lysine transport was about 10-fold higher in isotonic salt solutions than in solutions of nonionic osmolites, whereas the K m value for l-leucine transport was about the same in either type of solution. Therefore, inorganic and organic cations and the cationic portions of zwitterions appear to compete with cationic but not zwitterionic amino acids for system b 0,+ receptor sites. The cation, harmaline, was a particularly strong competitive inhibitor of ‘Na +-independent’ l-lysine uptake by system b 0,+, even in isotonic salt solutions, whereas it inhibited l-leucine uptake noncompetitively. Moreover, harmaline appeared to compete with inorganic cations for the lysine receptor sites of system b 0,+. Harmaline also has been found by other investigators to competitively inhibit l-lysine uptake by the Na +-independent system asc 1 in horse erythrocytes, whereas it noncompetitively inhibits alanine uptake by the same system. Similarly, harmaline noncompetitively inhibits l-alanine uptake by the Na +-dependent system ASC in human erythrocytes, but it appears to compete for binding with l-alanine's cosubstrate, Na +. In addition, others have found that the positively-charged side chains of cationic amino acids seem to take the place of Na + needed near side chains in order for zwitterionic amino acids to be transported by systems ASC and y +. We conclude that system b 0,+ may be similar to systems asc 1, ASC and y +, and that each of these systems may be a variant of the same ancestral transport process. We speculate that since it appears to accept a broader scope of substrates and to interact with a wider variety of cations than do systems asc 1, ASC or y +, system b 0,+ may more closely resemble the proposed ancestral transport process than any of the other contemporary systems.

Kinetics and mechanism of the processes of preparing fibre-forming polymers based on acrylonitrile. Review

The published data and the authors' results of the study of the kinetic features and mechanism of the reactions of formation of polymers and spinning solutions based on acrylonitrile are systematized. The dependences of the main kinetic parameters of homo- and copolymerization of acrylonitrile in organic and aqueous salt solutions on the concentration of initiator, monomer and solvent, temperature and acidity of the medium are reviewed and analysed. The kinetic patterns associated with the influence of the structure of the solvent on the elementary reactions of radical- chain homo- and copolymerization of acrylonitrile are noted and the quantitative characteristics of these recactions presented.

Degradation of exogenous MBP by myelin Ca 2+-activated neutral protease and effect of extraction of myelin on enzyme activity

Time-course of degradation of exogenous myelin basic protein (MBP) by myelin calcium-activated neutral protease (CANP) and the effect of different treatments with organic solvents and salt solutions on CANP activity were studied. Activity was estimated from the supernatants of incubation mixtures as primary amino groups released during proteolysis by a spectrophotometric method or from the protein patterns on SDS gels. Analysis of the time-course of bovine 18.3 K MBP proteolysis revealed a defined sequence of degradation, at least twelve peptides being observed. Bovine and mouse myelin CANPs degraded both bovine 18.3 K MBP and mouse 14.0 K MBP in a similar manner. On SDS gels the banding patterns of degradation of these proteins revealed differences as well as similarities. Delipidation of myelin with acetone did not affect on myelin CANP activity. Removal of lipid with ether:ethanol (3:2) slightly reduced activity, and after chloroform:methanol (2:1) extraction the residue had no CANP activity. The activity could not be established in the chloroform-methanol supernatant either. These findings together with extraction experiments with buffered salt solutions suggest that the enzyme molecule is tightly bound in the membrane interior and may require certain myelin lipids for activity. Analysis of the time-course experiment suggests that MBP in the membrane-bound form acts as a substrate for CANP, and soluble degradation products are released from the membrane.

Setschenow coefficients for caffeine, theophylline and theobromine in aqueous electrolyte solutions

Setschenow coefficient measurements have been made on methylated xanthines (caffeine, theophylline and theobromine) in several inorganic and organic aqueous salt solutions at 298 K. In general, the order of salting effect is similar for the three solutes and can be rationalized as a consequence of structural salt–water interactions. Scaled particle theory and the Cross and McTigue equation have been employed to compare theoretical and experimental salting constants.

Mild interaction of proteins with butyl and hydroxyl groups on the surface of polymer gels TSK HW-65 and butyl toyopearl 650-M

Interaction of bovine serum albumin (SBA) with butyl and hydroxyl groups on adsorben gel surfaces was investigated bu using TSK HW-65 adn Butyl Toyopearl 650-M gels. It was found that BSA was adsorbed on the gel not only from highly concentrated ammonium sulphate but also form dilute perchloric acid, trichloroacetic acid, etc. Some eluent modifier, such as organic solvents (30% aqueous methanol or acetonitrile), salt solutions (0.18–0.2 M phosphate) and hydrogen-bond breaking reagents (3–7 M urea, 10 M ethylene glycol, 0.1% triethylamine) were found to be effective in facilitating the elution of trapped BSA from the gel. The conformational change of BSA in these solutions was slight except for urea, and it was reversibly recovered after removal of the modifier from the aqueous solutions, except for the hydrogen-bond breaking reagents.