Suspensions Of Salts Research Articles

Understanding the Behavior of Sodium Polyacrylate in Suspensions of Silica and Monovalent Salts.

This study investigated the interaction of monovalent cations with different sizes on quartz surfaces and the rheological impact that this causes in concentrated suspensions when subjected to the action of a rheological modifier, in this case, sodium polyacrylate (NaPA). Yield stress was determined using a rheometer with a vane-in-cup configuration to establish the relationship between shear stress and strain. Experiments were carried out in LiCl, NaCl, KCl, and CsCl solutions. The results show that the yield stress increases following the order Li < Na < K < Cs in the absence of PAA. However, the addition of NaPA significantly reduced the yield stress in all cases. This reduction was more noticeable in the LiCl and NaCl solutions than in the KCl and CsCl solutions, suggesting a more pronounced effect of PA in maker salts. We conducted molecular dynamics simulations to understand how PA interacts with dissolved salts on the quartz surface. Our results showed that Li had the highest adsorption, followed by Na, K, and Cs. As the salt concentration increased, so did the adsorption. We validated these simulation results with rheological experiments, which helped us understand the observed differences. The molecular interactions indicate that, in the lithium system, cationic bridges and the synergy between hydrogen bridges and hydrophobic bridges predominate mainly. This tendency decreases as the type of cation is changed due to the decrease in the electrical density of the cation in the following order: Li < Na < K < Cs. This reduces bridging with the quartz surface and, therefore, directly impacts the system's rheological properties.

One Pot Synthesis of Dithiolane Dendron Functionalized Gold Nanoparticles

AbstractThe theranostic properties of gold nanoparticles (GNPs) depend on their size and shape but also on their challenging coating. Indeed, the GNPs coating step is not easy to perform and often affects their colloidal stability and aggregation state. We investigated the one‐pot synthesis of GNPs with a size higher than 10 nm and coated with dendrons by testing different synthesis processes. With the Brust‐Schriffin method, the very fast reduction of HAuCl4 affects the growth step. The decrease of the reduction kinetics by tuning the reaction temperature and the NaBH4 injection speed led to spherical GNPs with a size ∼30 nm. The seed mediated method conducted always to the presence of very small nuclei beside bigger GNPs despite a Ostwald ripening treatment. Finally, the modification of the gold precursor by tuning the pH of gold salt suspensions was shown very promising to better control the nucleation and growth steps and obtain dendronized GNPs in a one‐pot step (ratio 100 : 1 and pH=2.3).

Formation of metallic silver and copper in non-aqueous media by ultrasonic radiation

Concentrated suspensions of silver and copper salts in silicone oil were heated to 200 °C and irradiated with ultrasonic energy for different time durations. Characterization of the products was done using X-ray powder diffraction. In most cases, metallic Ag or Cu were obtained, together with their oxide forms Ag2O and Cu2O. The salts, used as precursors, do not dissolve in silicone oil but rather form a heterogeneous system, and we assume that local heating, caused by the acoustic cavitation, enhanced their thermal decomposition and the formation of metallic particles. It was found that the presence of silver particles enhances the formation of metallic copper. This phenomenon was observed in the experiment with the acetate salts mixture.

Wet Chemical Approach for Vanadium Doped Maghemite (Fe2-xVxO3) Nanocrystals

Background: Nanomaterials are widely synthesized by wet chemical routes. Magnetic nanoparticles with size ranging from 2 to 20 nm are of significant importance, resulting in a unique magnetic property of the nanoparticles. Maghemite nanostructures with partially disordered (Fe3+)[Fe5/3⁏1/3]O4 structures, undergo cation-insertion reactions without resorting to a drastic change in the material composition. Tailoring the superparamagnetic properties of nanoparticles by doping with transition metals, such as vanadium could be advantageous, as it would provide control over properties that are important for biological applications, such as magnetization dependent changes in temperature, relaxivity, and hysteresis. Method: We describe the obtention of vanadium doped maghemite (Fe2-xVxO3) from colloidal suspensions of vanadium and iron salts, using a precipitation–annealing method. A single step simpler synthesis scheme has been proposed in this work, with annealing temperature (350 °C), for a short period of time (~ 15 minutes), in order to achieve smaller in size but developed nanocrystals. Results: Superparamagnetic vanadium doped maghemite with particles (~8 nm) size has been synthesized. For the first time, vanadium up to 5 mol% has been doped on maghemite nanocrystals and characterized successfully for the presence of stable V3+. These results open a new era of vanadium applications in industrial Nanosciences; possessing superparamagnetic properties. Conclusion: A wet chemical route to direct the synthesis of vanadium doped γ- Fe2O3 nanocrystals, has been studied. The doping controls the crystallite size by occupying the vacant octahedral spaces available in the cubic system (space group P4332) maghemite crystals. High surface area magnetic particles, with an average size of ~8 nm were obtained. Keywords: Characterization, synthesis, vanadium doped maghemite.

Green synthesis of nano zinc oxide and evaluation of its impact on germination and metabolic activity of Solanum lycopersicum

In the present study, zinc oxide nanoparticles (ZnO NPs) were rapidly synthesized at room temperature by treating zinc acetate dihydrate with the flower extract of Elaeagnus angustifolia (Russian olive). The formation of ZnO NPs was primarily confirmed by UV–visible absorption spectrum in the range of 250–700nm. XRD analysis and DLS particle size analyzer revealed the size of ZnO NPs. The FTIR spectrum revealed the presence of phytochemicals in the flower extract mediated ZnO NPs. Moreover, the morphology of the ZnO NPs was determined using SEM. Seeds of Solanum lycopersicum (tomato) were separately treated with different concentrations of synthesized ZnO NPs and zinc sulphate (ZnSO4) salt suspensions (common zinc supplement). The effect of these treatments on seed germination, seedling vigor, chlorophyll, protein and sugar contents as well as on the activities of lipid peroxidation and antioxidant enzyme were studied. Leaves of plants treated with 6.1mM concentration of ZnO NPs recorded maximum reflectance while it was minimum in plants treated with 1.2mM concentration of NPs. The effect of synthesized ZnO NPs on seedling vigor, pigment, protein and sugar content was found affirmative at lower concentrations contrary to control and ZnSO4 salt. The inhibitory effect at higher concentration of NPs indicated importance in the precise application of NPs, in Zn deficient system, where plant response varies with concentration. To the best of our knowledge this is the first report on Elaeagnus angustifolia mediated synthesis of ZnO NPs and their effects on germination and physiological activity of tomato.

Structure, Ion Transport, and Rheology of Nanoparticle Salts

Above a critical surface chemistry-dependent particle loading associated with nanoscale interparticle spacing, ligand–ligand interactions—both electrostatic and steric—come into play and govern the structure and dynamics of charged oligomer-functionalized nanoparticle suspensions. We report in particular on the structure, ion transport, and rheology of suspensions of nanoparticle salts created by cofunctionalization of silica particles with tethered sulfonate salts and oligomers. Dispersion of the hairy ionic particles into medium and high dielectric constant liquids yields electrolytes with unique structure and transport properties. We find that electrostatic repulsion imparted by ion dissociation can be tuned to control the dispersion state and rheology through counterion size (i.e., Li+, Na+, and K+) and dielectric properties of the dispersing medium. Analysis of small-angle X-ray scattering (SAXS) structure factors and the mechanical modulus shows that when the interparticle spacing approaches nanomet...

Triboluminescence of crystals and suspensions of inorganic salts of lanthanides

It is found that the triboluminescence spectra of crystalline hydrates of inorganic salts of Ln3+ (Ce3+, Pr3+, Gd3+, Eu3+, Tb3+, and Dy3+) during mechanical trituration and ultrasonic treatment (22 kHz) of crystal suspensions in perfluorodecalin (in the sonotriboluminescence) exhibit gaseous and solid-state components. The first component contains emission lines of N2 in an electric discharge. The spectrum of the second component coincides with the photoluminescence spectrum of the crystals, including ions that cannot be excited due to the absorption of emission from N2: Ce3+, Pr3+, and Gd3+. Among the different salts of Ln3+, the highest intensity of luminescence is observed in sulfates; the highest yields of tribo- and sonotriboluminescence are characteristic of the Ce3+ salts. The triboluminescence of Ln3+ nitrates is not registered. Possible mechanisms of excitation of the Ln3+ ions are discussed. The main source of the solid-state component of the triboluminescence of Ln3+ salts is assumed to be the electroluminescence typical of crystalline phosphors. It is shown that, along with lines of N2, the spectrum of the triboluminescence observed in the atmosphere of He, Ar, and O2 contains lines of these gases.

Diflunisal salts of bupivacaine, lidocaine and morphine: Use of the common ion effect for prolonging the release of bupivacaine from mixed salt suspensions in an in vitro dialysis model

The present work describes the characterization of diflunisal salts of the analgesic agents bupivacaine, lidocaine, and morphine including their solubility behaviour and release characteristics from solutions and selected salt suspensions in vitro using the rotating dialysis cell model. The solubility of the 1:1 salts at pH 7.4 differed by a factor of 9 with the bupivacaine and lidocaine salts representing the poorest and most soluble salt (0.73 and 6.6 mM, respectively). Common ion effects were observed for the diflunisal salts of bupivacaine and morphine when various concentrations of the lidocaine-diflunisal salt were present in aqueous buffer (pH 7.4). The most pronounced salting-out effect was observed for the poorest soluble salt. From Setschenow type plots apparent salting-out constants of 265 M −1 (bupivacaine) and 54.7 M −1 (morphine) were calculated. After instillation of mixed salt suspensions comprising the diflunisal salts of bupivacaine and lidocaine into the donor cell of the release model, lidocaine appeared rapidly in the acceptor phase. After clearance of lidocaine from the donor cell, equal and constant fluxes of bupivacaine and diflunisal were observed. The residence times of bupivacaine within the donor compartment was prolonged with increasing lidocaine-diflunisal salt load in the mixed suspensions whereas the slopes of the linear part of the bupivacaine release profiles were affected to a minor extent only. The obtained data indicate that local multimodal analgesia, characterized by rapid onset and extended duration of action, can be achieved upon injection of mixed suspensions of salts differing with respect to aqueous solubility comprising a common ion into a small body compartment (such as the joint cavity).

Sedimentation of binary mixtures of like- and oppositely charged colloids: the primitivemodel or effective pair potentials?

We study the sedimentation equilibrium of low salt suspensions of binary mixtures ofcharged colloids, both by Monte Carlo simulations of an effective colloids-only system andby Poisson–Boltzmann theory of a colloid–ion mixture. We show that the theoreticallypredicted lifting and layering effect, which involves the entropy of the screening ions and aspontaneous macroscopic electric field (Zwanikken and van Roij 2005 Europhys. Lett. 71480), can also be understood on the basis of an effective colloid-only system withpairwise screened-Coulomb interactions. We consider, by theory and by simulation,both repelling like-charged colloids and attracting oppositely charged colloids,and we find a re-entrant lifting and layering phenomenon when the charge ratioof the colloids varies from large positive through zero to large negative values.

Interaction between dams and powder avalanches: determination of simple friction laws for shallow water avalanche models

One of the goals of the European project CADZIE was the determination of simple friction laws for shallow water avalanche models in order to describe the interaction between defense structures and powder as well as dense avalanches. In this paper, we will focus on powder avalanches. We carried out physical model experiments in a water tank, in which the powder snow was simulated by a “heavy” salt solution. Respecting both the densimetric Froude number and the density ratio to meet the laws of similarity required a prohibitively large tank. Practically, a distortion of the density ratio must be accepted. A ratio of 1.2 can be achieved in the water tank with salt suspensions, whereas powder avalanches attain ratios of the order of 10. Quasi-two and three-dimensional experiments with several configurations of dams were conducted in the water tank and the internal velocity of the flow was measured using Doppler ultrasonic velocimetry. Numerical simulations of such experiments were done using a turbulent “heavy gas” model: two mass balances, one for mixture and one for the salt solution are considered, but only one momentum balance for the entire mixture implying that both water and salt solution are assumed to move with the same velocity. The obtained results were compared with measurements obtained in the water tank and the effect of density ratio was numerically studied. As it was shown that the entrainment of air is modified by the density ratio, friction coefficients were determined for different density ratio (2.5 and 10) and for different values of dam's height (from 0.2 to 0.6 H 0, where H 0 is the height of the reference avalanche). The practical use of such coefficient tables is shown.

Polarography in solution of some problems in organic chemistry: recent applications

Applications of chromatographic and atomic absorption methods are compared with those of electroanalytical techniques. The limitations of electroanalytical procedures and their advantages, such as speed, sensitivity and speciation are discussed. Among applications of polarography and voltammetry to a solution of basic problems, attention has been paid to the possibility to distinguish the degree of conjugation (e.g. of compounds containing the grouping CNNC), to a contribution to understanding of solution chemistry of mitomycin C and to processes involved in the reduction of cephalosporins. Among practical applications, the possibility to analyze suspensions, which can be carried out without separation offers advantages. Examples are interactions in suspensions of bile salts in the presence of metal (II) ions, adsorptions of various pesticides and other toxic materials on lignin and the possibility to follow alkaline cleavage of lignin in buffers pH 8–12 at 25 °C. Most of these studies would not be possible to carry out using other techniques.

Soil acidity in 1970 and 1989 in a coniferous forest in southwest Finland

Forest soil pH in southwest Finland was measured with identical sampling and analysing methods in 1970 and 1989. The acidity of the organic humus layer increased significantly as pH values measured on water and on salt suspensions decreased between the two sampling dates. For the mineral soil layers, no unambiguous trend was found. pH values measured on salt suspension tended to be unchanged or lower, while pH on water suspension in some soil layers were even higher in 1989 than in 1970. Key words: pH, repeated sampling

Levels of total cyanide and NaCl in surface waters adjacent to road salt storage facilities

Concentrations of Na, Cl and total cyanide (simple+complex forms of cyanide) in surface waters adjacent to uncovered, outdoor sand-salt storage facilities were monitored for the calendar year 1988. Runoff of deicing salt from these unprotected sand-salt piles resulted in Cl concentrations up to 13 500 mg liter −1 in surrounding surface waters indicating substantial leaching of road salt from sand-salt storage lots. The use of sodium hexacyanoferrate (II) as an anti-caking agent in road salt resulted in up to 200 μg liter −1 total cyanide (CN) in surface waters adjacent to sand-salt piles. Concentrations of Na and Cl were highest during the summer months whereas the concentrations of total CN were highest during the autumn months. The observed concentrations of total CN were less than the calculated maximum concentrations based on total CN content of pure road salt indicating that sodium hexacyanoferrate(II) was being adsorbed during overland flow onto soils and/or sediments of the wetlands. A laboratory adsorption study using five soils and a road salt solution showed that the soils adsorbed from 25 to 83% of the sodium hexacyanoferrate(II) present in the soil-road salt suspensions. The percentage of sodium hexacyanoferrate(II) adsorbed on soils increased with decreasing soil pH.

Soluble Fluid-Loss Additives Can Reduce Well Productivities and Prevent Complete Gravel Placement

Summary Fluid-loss additives are frequently used in completion fluids and pills to reduce fluid costs and formation damage, but many of these additives create more damage than they prevent. Common recommendations are to use fluid-loss additives that will be dissolved by the produced fluids, acid, or water so that they may be readily removed after a job. Typical additives are oil-soluble resins, calcium carbonate particles, and salt suspensions. It is particularly important that soluble additives be used for wells that are to be gravel packed because the gravel will trap insoluble solids in the well. Evidence indicates, however, that even these soluble products remain in perforation tunnels and impair productivities of wells. Examples of wells indicating this effect during post-gravel-pack acid treatments are discussed. The theory of why this occurs and calculations of pressure drops through perforations filled with fluid-loss additives are presented. It has also been found that excess fluid-loss additives prevent complete coverage of a zone with gravel, because of either inadequate leakoff to the formation or partial plugging of the screen. Therefore, it is imperative that these additives be removed by acid, water, or solvents preceding the gravel slurry; however, if their removal causes loss of circulation, the results may be equally bad. The most practical solution to this problem is to use a combination of gravel and viscous fluids as a diverting system for the fluids that will remove the additives without creating additional formation damage. When this system is used just ahead of a gravel slurry, it not only helps remove the fluid-loss additives, but also helps prevent excessive fluid losses and partially prepacks the formation with gravel.

Binding of calcium and lead ions to carboxystarch prepared by action of nitrogen dioxide on native starch and its 2,3-dialdehyde derivatives

The binding of calcium and lead ions to carboxy derivatives of starch prepared by allowing nitrogen dioxide to act on native maize starch (procedure A) and on starch 2,3-dialdehyde derivatives of degrees of oxidation DO(d.a.) ≥ 0.94 (procedure B) was studied. The carboxy group content of the samples in the H+ form was 4.6 - 12.1 mmol g-1. The effect of alkaline medium on the stability of the carboxy derivatives and on their ability to bind and exchange cations was examined. The Ca2+ → 2K+ exchange was evaluated in terms of the decrease in the electrostatic free enthalpy Δ(Gel/N)KCa, determined by alkalimetric potentiometric titrations, and the binding of Pb2+ ions was evaluated in terms of the activity of the Pb2+ counter-ions determined in suspensions of Pb salts of the carboxy derivatives by means of an ion specific electrode. The IR and CD spectra revealed that the carboxystarch preparations obtained by procedure A contained, in addition to free carboxy groups, a considerable amount of carbonyl groups. During the conversion of the latter groups to the former, even in a weakly alkaline medium, the carboxy derivatives undergo an appreciable degradation and lose, to a great extent, their ability to bind and exchange cations. Procedure B, on the other hand, leads to highly selective starch and amylose carboxy derivatives, exhibiting a small amount of carbonyl groups and featuring a relative stability towards alkaline medium; their binding capacity is as high as 12 milliequivalents of cations per g of sample.

PH-Solubility Profiles of Organic Bases and Their Hydrochloride Salts.

Knowledge of comparative solubility profiles of a base and its hydrochloride salt is important in selecting one form over the other for dosage form design. The studies with two model bases, namely, tiaramide and papaverine, showed that, except during phase transition from a base to a salt or vice versa, the pH-solubility profiles are identical whether a base or a salt are used. The solubilities were determined by equilibration after addition of hydrochloric acid or sodium hydroxide solutions to suspensions of bases and salts. With the addition of hydrochloric acid solution, the pH values of the suspensions of tiaramide and papaverine dropped to 5.0 ± 0.1 and 4.0 ± 0.1, respectively, and then remained constant until supersaturated solutions were formed. After nucleation of supersaturated solutions with the addition of hydrochloride salt or the reduction of temperature, the precipitation of hydrochloride salt occurred. The solubilities of salts decreased at low pH due to common ion effect. The K(o) sp values, however, did not remain constant and the solubility profiles showed positive deviations from the theoretical ones. These may be due to a possible self-association and the resultant difference between the solubilities and activities of the compounds in solutions. The reported differences between the solubilities of bases and their respective hydrochloride salts at a particular pH and the lack of common ion effects on the solubilities and dissolution rates of bases are explained.

Pulmonary toxicity of beryllium in albino rat.

Arsenic compounds, if chronically exposed to human beings, significantly increase incidences of epidermoid carcinomas of the skin and lung. Nickel has been considered to be an important metallic carcinogen. Regarding beryllium, different opinions are held so far as its carcinogenic nature is concerned. While it is reported that there is an equivocal increase in the incidences of respiratory cancers in patients with chronic pulmonary berylliosis, investigation shows no increase in the incidence of respiratory cancer. Among experimental animals, intravenous injections of suspensions of beryllium salts to rabbits have been shown to induce osteogenic sarcomas. This abstract deals with the histopathological and enzymological study of lungs of albino rats after prolonged beryllium treatment.

Aluminum Organic Matter in Acid Soils: Buffering and Solution Aluminum Activity

AbstractThe variation of solution Al3+ activity with pH, the effect of suspending salt solution cation on Al3+ activity, and the buffering intensity were determined for salt solution suspensions of three soil samples and an Al substituted peat that contained one equivalent of Al3+ for each equivalent of carboxyl groups. The soil samples used were a surface and a subsurface horizon of an Inceptisol from New York and a surface horizon of an Oxisol from Brazil. The soils were equilibrated for periods of up to 35 days in 0.02N solutions of the chlorides of K+, Na+, Ca2+, Mg2+, Cu2+ and La3+ with the addition of acid or base. In the pH range 3.9 to 4.9, plots of pH vs. pAl were linear with ΔpAl/ΔpH&lt;2.5, significantly different from the value of 3 predicted by Al(OH)3 solubility. At a given pH, Al3+ activity was a function of the solution cation. The Al substituted peat in 0.02N CaCl2 gave a pH vs. pAl plot very similar to that of the surface horizon of the Inceptisol. Also, the addition of partially rotted leaf humus to the Inceptisol subsoil caused a reduction of Al3+ activity at any given pH even after 35 days of equilibration.It was concluded that hydrolysis of organically bound Al is a major source of buffering in the pH range of 4 to 5 for dilute salt suspensions of acid soils and that exchange of Al ions from organic matter exchange sites controls the relationship between pH and Al3+ activity in acid soils that have a low amount of permanent charge CEC relative to the quantity of organic matter.

Lateral flow in beech and birch as revealed by the electron microscope

Sapwood of beech and birch was impregnated with aqueous salt solutions and suspensions of carbon particles and india ink under a low initial pressure; the pathways marked by the impregnating substances were examined by the electron microscope. The micrographs revealed dark deposits in cell lumina, pit membranes, and other parts of the cell wall. The size of voids occupied by dark deposits ranged from infinitely small to 700 A in vessels and rays, and from infinitely small to 1,300 A in fibers. It was concluded that the penetration path of impregnating substances from one cell to the next was through the minute intermicrofibrillar openings in the communicating pit membranes and in the rest of the cell walls. Carbon particles, suspended in plastic monomer, were not observed either in pit membranes or in the rest of the cell wall; they probably represent a nonpolar substance.

Photoselection and aggregation in purple membrane of Halobacterium halobium

Preparations of the purple membrane of Halobacterium halobium suspended in dilute buffer and basal salt have been examined by circular dichroism spectroscopy and correlation analysis of scattered laser light. Dark adapted samples suspended in basal salt show photoselection when examined by circular dichroism. This was confirmed by irradiation with plane polarized light. Light-adapted samples or dark-adapted samples suspended in dilute buffer did not show this phenomenon. The reaction responsible for photoselection was shown to be the light induced cis-trans isomerization of bacteriorhodopsin. The stability of the induced anisotropy was due to aggregation in the basal salt suspensions which occurred despite little or no visual indication. This aggregation was confirmed by correlation analysis of scattered laser light.