Статті в журналах: "Acid solutions"

1

Pasenko, O., A. Mandryka, Ye Khrupchyk, and V. Vereshchak. "Stable solutions of orthosilicic acid." Voprosy Khimii i Khimicheskoi Tekhnologii, no. 4 (July 2022): 56–60. http://dx.doi.org/10.32434/0321-4095-2022-143-4-56-60.

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Soluble silicon plays a significant role in living organisms. Orthosilicic acid is the only bioavailable form of silicon. Sodium silicate solutions with various silicate moduli and different types of acids were used in our work to investigate the effect of silicate modulus and types of acids on the stability of the solutions of orthosilicic acid. It was determined that both the silicate modulus and the type of acid have a certain impact on the stability of orthosilicic acid solution. The effect of sulfuric, hydrochloric, orthophosphoric and methanesulfonic acid on the stability of orthosilicic acid solutions was studied depending on the silicate modulus of sodium silicate. It was shown that in the following series of anions SO42–, Cl–, CH3SO3–, PO43–, the stability of orthosilicic acid solutions increases. In the following series of alkaline modulus 3.02, 2.72, 2.06, 1.96, the stability increases too. The use of orthophosphoric acid and liquid glass with a silicate modulus of 1.96 allowed obtaining a solution, which is stable for at least 40 days.

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2

Serheyev, Valentyn, Yuriy Kos, and Yuriy Van-Chin-Syan. "Thermodynamic Properties of Solutions of Ethacrylic Acid in Acetonitrile and Acetic Acid." Chemistry & Chemical Technology 9, no. 2 (May 15, 2015): 131–35. http://dx.doi.org/10.23939/chcht09.02.131.

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3

Park, Min Sun, Olof Heimbürger, Jonas Bergström, Jacek Waniewski, Andrzej Werynski, and Bengt Lindholm. "Peritoneal Transport during Dialysis with Amino Acid-Based Solutions." Peritoneal Dialysis International: Journal of the International Society for Peritoneal Dialysis 13, no. 4 (October 1993): 280–88. http://dx.doi.org/10.1177/089686089301300404.

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Objective To evaluate the potential clinical role of amino acids as an osmotic agent. Design The peritoneal transport of fluid, amino acids, and other solutes was investigated during a 6–hour single-cycle peritoneal dialysis with PDA 1% versus 1.36% glucose (n=6) or PDA 2.7% versus 3.86% glucose solution (n=9). Patients Fifteen stable nondiabetic continuous ambulatory peritoneal dialysis (CAPD) patients. Results The fractional absorption of the osmotic agents at 6 hours was higher with PDA 2.7% versus glucose 3.86% (p<0.005). The diffusive mass transport coefficient, KeD’ calculated for a period of dialysate isovolemia was higher with PDA 2.7% versus PDA 1% for essential, nonessential (p<0.005), and total (p<0.05) amino acids. The intraperitoneal volume-over-time curves and KqD values for urea, creatinine, glucose, albumin, β2microglobulin, and total protein did not differ between the amino acid solutions and the corresponding glucose solutions. KeD for urea was significantly higher during the dwell with PDA 2.7% versus PDA 1% (p<0.05). Plasma amino acid concentrations increased substantially during the first 1– 2 hours and then decreased gradually. Valine and methionine rose to 792% and 1119% of baseline values, respectively. Conclusions We conclude that the peritoneal transport of fluid and investigated solutes, except amino acids, was not different with the amino acid solutions compared with the corresponding equimolar glucose solutions. However, ultrafiltration tended to be lower with amino acid solutions. Furthermore, the fractional absorption of amino acids and KeD values for amino acids was higher with PDA 2.7% versus PDA 1 %, suggesting an effect of the hypertonic amino acid solution on the peritoneal membrane transport properties. Also, the hypertonic PDA2.7% solution yielded nonphysiologically high plasma levels of several amino acids. We therefore consider this solution not to be safe enough for long term clinical use.”

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4

Serheyev, Valentin, Yuri Kos, and Yuri Van-Chin-Syan. "Thermodynamic Properties of Solutions of the Acrylic Acid in 1,2-Dichloroethane and Acetic Acid." Chemistry & Chemical Technology 5, no. 2 (June 15, 2011): 123–27. http://dx.doi.org/10.23939/chcht05.02.123.

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5

Cheon, Eunjin, and Richard Mattes. "Fatty Acids Taste Intensity Ratings Before and After Sour Taste Adaptation." Current Developments in Nutrition 4, Supplement_2 (May 29, 2020): 742. http://dx.doi.org/10.1093/cdn/nzaa052_011.

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Abstract Objectives Recent research indicates that the taste quality of fatty acids, called ‘Oleogustus’, differs from the traditionally accepted five basic tastes. However, the actual quality of the sensation has not been characterized. One question is whether there is a sour component because very short-chain fatty acids, like acetic acid, the sour tastant in vinegar, is structurally a fatty acid. The present study investigated the quality sensation of fatty acids of graded chain length. Methods Sensory stimuli were acetic acid, butyric acid, hexanoic acid, octanoic acid, decanoic acid, lauric acid, oleic acid, and linoleic acid emulsions and palmitic acid, stearic acid powder. The intensity of the samples before and after expectorating was measured. Next, participants repeatedly sipped, held for 5 seconds, and expectorated a sour solution (0.09% w/w) and rated the intensity on a gLMS until the intensity was lower than “weak”. After adaption to the sour solution, the intensity of the sample was measured before and after expectorating. Participants recorded the quality of each sample. Results The intensity of acetic acid was significantly lower after adaptation (P < 0.04) that before adaptation and a similar trend was noted for butyric acid. The other fatty acids were not affected by adaptation. The intensities of all liquid samples except the octanoic acid solution showed a significant difference between before and after expectorating the samples. The intensities of acetic, butyric and hexanoic acids were lower after expectorating the samples than the intensities before expectorating the samples (P < 0.05) while the intensities of decanoic acid, lauric acid, oleic acid, and linoleic acid (P < 0.05) were lower after expectorating. There was no significant difference in intensity of the palmitic acid solution and the intensity of the stearic acid solution between before and after expectorating. Conclusions The results showed that fatty acids with chain lengths great than 4 have a unique taste other than the sourness. In addition, short-chain fatty acid solutions had higher intensity before expectorating the solutions while the medium- and long-chain fatty acid solutions had higher intensity after expectorating solutions, indicating that there is a different persistence time for fatty acid directly related to chain-length. Funding Sources This study has no sponsors.

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6

Tran, Anh T., Jay Tomlin, Phuoc H. Lam, Brittany L. Stinger, Alexandra D. Miller, Dustin J. Walczyk, Omar Cruz, Timothy D. Vaden, and Lei Yu. "Conductivity, Viscosity, Spectroscopic Properties of Organic Sulfonic Acid solutions in Ionic Liquids." ChemEngineering 3, no. 4 (October 1, 2019): 81. http://dx.doi.org/10.3390/chemengineering3040081.

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Sulfonic acids in ionic liquids (ILs) are used as catalysts, electrolytes, and solutions for metal extraction. The sulfonic acid ionization states and the solution acid/base properties are critical for these applications. Methane sulfonic acid (MSA) and camphor sulfonic acid (CSA) are dissolved in several IL solutions with and without bis(trifluoromethanesulfonyl)imine (HTFSI). The solutions demonstrated higher conductivities and lower viscosities. Through calorimetry and temperature-dependent conductivity analysis, we found that adding MSA to the IL solution may change both the ion migration activation energy and the number of “free” charge carriers. However, no significant acid ionization or proton transfer was observed in the IL solutions. Raman and IR spectroscopy with computational simulations suggest that the HTFSI forms dimers in the solutions with an N-H-N “bridged” structure, while MSA does not perturb this hydrogen ion solvation structure in the IL solutions. CSA has a lower solubility in the ILs and reduced the IL solution conductivity. However, in IL solutions containing 0.4 M or higher concentration of HTFSI, CSA addition increased the conductivity at low CSA concentrations and reduced it at high concentrations, which may indicate a synergistic effect.

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7

Boichenko, Alexander, Vadim Markov, Hoan Kong, Anna Matveeva, and Lidia Loginova. "Re-evaluated data of dissociation constants of alendronic, pamidronic and olpadronic acids." Open Chemistry 7, no. 1 (March 1, 2009): 8–13. http://dx.doi.org/10.2478/s11532-008-0099-z.

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AbstractThe dissociation constants of (4-amino-1-hydroxybutylidene)bisphosphonic (alendronic) acid, (3-(dimethylamino)-1-hydroxypropylidene)bisphosphonic (olpadronic) acid and (3-amino-1-hydroxypropylidene)bisphosphonic (pamidronic) acid were obtained in aqueous solutions (0.10 M KCl) and micellar solutions of cetylpyridinium chloride (0.10 M CPC) at 25.0°C. With the exception of the third dissociation constant of alendronic acid, the dissociation constants of alendronic, olpadronic and pamidronic acids in aqueous solutions matched literature data. The possibility of sodium alendronate determination by acid-base titration by NaOH solution was theoretically grounded on the basis of re-evaluated data of alendronic acid dissociation constants.

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8

Pilipenko, Alexei, Antonina Maizelis, Hanna Pancheva, and Yulia Zhelavska. "Electrochemical Oxidation of VT6 Titanium Alloy in Oxalic Acid Solutions." Chemistry and Chemical Technology 14, no. 2 (June 15, 2020): 221–26. http://dx.doi.org/10.23939/chcht14.02.221.

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9

Bessarab, O. V., T. F. Platonova, and I. V. Protunkevitch. "Modeling of the corrosion process in the interaction of tinplate with vegetable canned food." Proceedings of the Voronezh State University of Engineering Technologies 81, no. 1 (July 18, 2019): 149–59. http://dx.doi.org/10.20914/2310-1202-2019-1-149-159.

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When choosing metal packaging for canned vegetables, it is advisable to take into account their corrosivity, because the inner surface corrosion is one of the factors affecting product quality during storage. To rationalize the corrosion tests of metal packaging materials, it is advisable to replace food with model media – organic acids solutions. The aim of this work was to study the corrosion kinetics of electrolytic tinplate in model media–aqueous solutions of oxalic (mass fraction 0.25–1.00%) and citric (mass fraction 0.25–1.50%) acids, as well as their compositions. The uniform corrosion rate was measured by the linear polarization resistance method, pitting corrosion–zero resistance amperometry method. The tests were carried out using the “Expert-004” corrosion-meter, according to a two-electrode scheme. For oxalic acid solutions with a mass fraction of 0.25% and 0.50% and for all citric acid solutions, the process is characterized as uniform corrosion – the pitting corrosion rates average steady values are 7–11 times less than the corresponding uniform corrosion rates values (1.52–3.93 µm/year and 17.42–26.56 µm/year, respectively). The most aggressive with respect to tinplate are oxalic acid solutions with a mass fraction of 0.25 and 0.50% and citric acid solutions with a mass fraction of 0.25 and 0.50%. On this basis, two-component solutions of the following composition were chosen: 0.25% citric acid + 0.25% oxalic acid; 0.25% citric acid + 0.50% oxalic acid; 0.50% citric acid + 0.25% oxalic acid; 0.50% citric acid + 0.50% oxalic acid. For these solutions, the process is characterized as uniform corrosion — the pitting corrosion rates average steady values are 7–10 times less than the corresponding the uniform corrosion rates values (2.04–3.85 ?m/year and 19.56–26.93 ?m/year, respectively). For two-component solutions, an additive effect is observed–the uniform and pitting corrosion rates average experimental steady values correspond to the calculated additive values. By mathematical processing of experimental data, it was found that the uniform corrosion steady rate maximum value the corresponds to a two-component solution containing 0.40% citric acid and 0.30% oxalic acid. This is confirmed by experimental data–the uniform corrosion rate average steady value for this solution is 28.18 ?m/year. According to the research results it was found that as a model corrosive medium that simulates canned vegetables, it is advisable to use a solution containing 0.40% citric acid and 0.30% oxalic acid, because it is the most aggressive.

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10

Bulstrode, C. J. K., A. W. Goode, and P. J. Scott. "A prospective controlled trial of topical irrigation in the treatment of delayed cutaneous healing in human leg ulcers." Clinical Science 75, no. 6 (December 1, 1988): 637–40. http://dx.doi.org/10.1042/cs0750637.

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1. Topical irrigation with normal saline is known to produce rapid healing in chronic leg ulcers. This study was designed to determine if the rate of healing could be improved by the addition of topical nutrition to the irrigating solution. 2. Forty-eight patients with chronic leg ulcers were admitted to hospital for a minimum of 6 weeks bed-rest. During this time the ulcers were continuously irrigated by one of four test solutions. The solutions were: normal saline; a dilute amino acid solution isotonic with the normal saline; a hyperosmolar saline solution; a hyperosmolar amino acid solution. There were 12 ulcers in each group. 3. The amino acid solutions produced significantly faster healing than the saline solutions (P < 0.01). Concentration had no significant effect on healing (P > 0.15). 4. The application of amino acids does appear to enhance healing in this model of delayed wound healing. This effect does not depend only on the osmolarity of the solution used.

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11

Poznyak, Alexander, Andrei Pligovka, Ulyana Turavets, and Małgorzata Norek. "On-Aluminum and Barrier Anodic Oxide: Meeting the Challenges of Chemical Dissolution Rate in Various Acids and Solutions." Coatings 10, no. 9 (September 10, 2020): 875. http://dx.doi.org/10.3390/coatings10090875.

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The chemical dissolution—in 0.1 M solutions of phosphoric, malonic, citric, sulfosalicylic, and tartaric acids and 0.6 M solutions of sulfuric, oxalic, malonic, phosphoric, tartaric, and citric acids—of aluminum (Al) and its barrier anodic oxide, with thicknesses of 240 and 350 nm, produced during the anodization of Al deposited on a sitall substrate and Al foil, respectively, in a 1% citric acid aqueous solution, was investigated. Signs of chemical dissolution for 0.1 M phosphoric acid solution and 0.6 M concentrations of all the listed solutions were found. It was shown that the dissolution rate and the nature of its change depend on the acid nature, the state of the sample surface, and the classification of the electrolytes according to their degrees of aggressiveness with respect to aluminum.

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12

Johannessen, Jan N. "Stability of Domoic Acid in Saline Dosing Solutions." Journal of AOAC INTERNATIONAL 83, no. 2 (March 1, 2000): 411–12. http://dx.doi.org/10.1093/jaoac/83.2.411.

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Abstract Studies designed to assess the effects of repeated low doses of domoic acid require an assessment of its stability in solution under the conditions used for in vivo studies. The stability of 1 mg/mL solutions of domoic acid in saline, with or without ascorbic acid, was determined for 15 weeks. Solutions were refrigerated, but warmed to room temperature for several hours each working day to simulate conditions of actual use. The solutions of domoic acid showed no evidence of decomposition as evidenced by stability of UV absorbance spectrum, concentration of domoic acid as determined by a liquid chromatographic method, and the chromatographic elution pattern. The addition of ascorbate to the domoic acid/saline solution did not alter the stability, but was deemed unnecessary because of the firm stability of the domoic acid/saline solution.

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13

Varga, Z., G. Kiss, and H. C. Hansson. "Modelling the cloud condensation nucleus activity of organic acids." Atmospheric Chemistry and Physics Discussions 7, no. 2 (April 19, 2007): 5341–64. http://dx.doi.org/10.5194/acpd-7-5341-2007.

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Abstract. In this study vapour pressure osmometry was used to determine water activity in solutions of organic acids. The surface tension of the solutions was also monitored in parallel and then Köhler curves were calculated for nine organic acids (oxalic, malonic, succinic, glutaric, adipic acid, maleic acid, malic acid, citric acid and pinonic acid). Surface tension depression is negligible for most of the organic acids in dilute (≤1 w/w%) solutions. Therefore, these compounds affect the supersaturation only in the beginning phase of droplet formation but not necessarily at the critical size. An exception is cis-pinonic acid which remarkably depress surface tension also in dilute (0.1 w/w%) solution and hence at the critical point. The surface tension of organic acid solutions is influenced by the solubility of the compound, the length of the carbon chain and also by the polar functional groups present in the molecule. Similarly to surface tension solubility plays an important role also in water activity: compounds with higher solubility (e.g. malonic, maleic, and glutaric acid) reduce water activity significantly in the early phase of droplet formation while less soluble acids (e.g. succinic and adipic acid) are saturated in small droplets and the solution starts diluting only in bigger droplets. As a consequence, compounds with lower solubility have a minor effect on water activity in the early phase of droplet formation. To deduce the total effect Köhler curves were calculated and critical supersaturations were determined for the organic acids using measured surface tension and water activity. It was found that critical supersaturation grew with growing carbon number. Oxalic acid had the lowest critical supersaturation in the size range studied and it was comparable to the activation of ammonium sulfate. The Sc values obtained in this study were compared to data from CCNC measurements. In most cases good agreement was found.

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14

Jones, Michael, Roberto Kalil, Peter Blake, Leo Martis, and Dimitrios G. Oreopoulos. "Modification of An Amino Acid Solution for Peritoneal Dialysis to Reduce Risk of Acidemia." Peritoneal Dialysis International: Journal of the International Society for Peritoneal Dialysis 17, no. 1 (January 1997): 66–71. http://dx.doi.org/10.1177/089686089701700114.

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Objective Some patients develop a mild acidemia during treatment with amino acid-based peritoneal dialysis solutions due to hydrogen ion produced by metabolism of lysine, arginine, and methionine. In this study we modified the formulation of such a solution by reducing these amino acids and adding anionic amino acids so as to provide minimal net acid production. Design A modified formula (MF) was compared to a conventional formula (CF) of the solution in a randomized crossover study in 12 stable continuous ambulatory peritoneal dialysis patients. Patients were given each solution for 14 days without a wash-out period. Each patient replaced one or two dextrose dialysis exchanges with amino acid solution, depending upon oral protein intake and body weight. Total intake (oral protein plus amino acids absorbed) was equivalent to 1.1 -1.3 g protein/kg body weight/day.Plasma bicarbonate and urea were assessed at the beginning and end of each 14-day period. Results In the group as a whole, without regard to the order in which the solutions were given, patients had a decrease in serum bicarbonate with CF and an increase in bicarbonate when they received MF. Similar trends were observed regardless of the order in which the solutions were administered. Serum urea did not differ between the two solutions. Conclusion The results suggest that patients are less prone to develop acidemia when receiving MF as opposed to CF. Further studies will be necessary to determine the long-term effects and the relative nutritional benefits of the two solutions.

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15

Sadeghi, Rahmat. "Modification of the NRTL and Wilson models for the representation of phase equilibrium behavior of aqueous amino acid – electrolyte solutions." Canadian Journal of Chemistry 86, no. 12 (December 1, 2008): 1126–37. http://dx.doi.org/10.1139/v08-166.

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The extended NRTL and Wilson local composition models for amino acid solutions have been modified for the representation of the phase equilibrium behavior of aqueous amino acid – electrolyte solutions by considering cells with random composition for the reference Gibbs energies or enthalpies of local composition cells with a central amino acid molecule and also with a central ion. These new local composition models, which have a molecular thermodynamic framework, have been used to model the vapor–liquid and solid–liquid equilibrium behavior of amino acids and small peptides in aqueous solutions as functions of temperature, ionic strength, and amino acid compositions. The utility of the models is demonstrated with a successful representation of the activity coefficients and the solubility of several amino acids in different aqueous solutions.Key words: amino acid, NRTL, Wilson, activity coefficient, solubility, aqueous solution.

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16

Alguacil, F. J. "Extraction of As (V) from sulphuric acid solutions by Cyanex 925." Revista de Metalurgia 34, Extra (May 30, 1998): 385–89. http://dx.doi.org/10.3989/revmetalm.1998.v34.iextra.777.

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17

Smith, James N., and Michael R. Evans. "Humic Acid Promotion of Root Development on Euphorbia pulcherrima Cuttings." HortScience 32, no. 3 (June 1997): 477A—477. http://dx.doi.org/10.21273/hortsci.32.3.477a.

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Vegetative 6-cm Euphorbia pulcherrima `Freedom' cuttings were placed in black 200-ml bottles containing humic acid solutions, nutrient solutions, or deionized water. Humic acid solutions were prepared using Enersol SC (American Colloid, Arlington Heights, Ill.). Concentrations of 500, 750, and 1000 mg/L humic acid were compared to solutions containing mineral element concentrations equivalent to those contained in humic acid solutions. After 4 weeks, 88%, 75%, and 88% of cuttings had rooted in the 500, 750, and 1000 mg/L humic acid solutions, respectively. Cuttings placed in nutrient controls or deionized water failed to form roots after 4 weeks. Average root fresh mass was 175, 80, and 72 mg for cuttings placed in 500, 750, and 1000 mg/L humic acid solution, respectively. Average number of roots formed per cutting ranged from 21 in the 500-mg/L solution to 6 in the 1000-mg/L solution. Average lengths ranged from 26 mm in the 500-mg/L to 12 in the 1000-mg/L solution. As humic acid concentration increased, average root fresh mass, average number of roots, and the length of the longest root significantly decreased.

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18

Sadyrbaeva, Tatiana. "Electrodeposition of Cobalt and Lead in the Hybrid Liquid Membrane - Electrodialysis-Electrolysis Process." Key Engineering Materials 721 (December 2016): 399–403. http://dx.doi.org/10.4028/www.scientific.net/kem.721.399.

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A novel method for Co (II) and Pb (II) recovery from acidic solutions is presented. The extraction of Co (II) and Pb (II) ions using the bulk liquid membranes during a galvanostatic electrodialysis process accompanied by cathodic electrodeposition of the metals was studied. Solutions of di (2-ethylhexyl) phosphoric acid (D2EHPA) with admixtures of tri-n-octylamine (TOA) in 1,2-dichloroethane were used as the liquid membranes. Effects of current density, Co (II) and Pb (II) concentrations in the feed solution, sulfuric or nitric acid concentration in the feed solution, D2EHPA and TOA concentration in the liquid membrane, of the type and concentration of acid in the cathodic solution were studied, and optimal conditions were determined. It is demonstrated that a practically complete (98-99%) removal of Co (II) and Pb (II) from the feed solutions containing 0.01 mol∙L-1 CoSO4 or 0.01 mol∙L-1 Pb (NO3)2 is achieved during 1.0 − 4.0 h of electrodialysis. A possibility of effective transfer of Pb (II) into dilute solutions of perchloric and nitric acids was demonstrated. The liquid membranes ensure the recovery of Co (II) ions into dilute solutions of perchloric, sulphuric, hydrochloric and nitric acids. Adherent, compact cobalt and lead electrodeposits with a fine-grained structure were obtained in the studied systems.

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Soto-Herranz, María, Mercedes Sánchez-Báscones, Juan Manuel Antolín-Rodríguez, and Pablo Martín-Ramos. "Evaluation of Different Capture Solutions for Ammonia Recovery in Suspended Gas Permeable Membrane Systems." Membranes 12, no. 6 (May 31, 2022): 572. http://dx.doi.org/10.3390/membranes12060572.

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Gas permeable membranes (GPM) are a promising technology for the capture and recovery of ammonia (NH3). The work presented herein assessed the impact of the capture solution and temperature on NH3 recovery for suspended GPM systems, evaluating at a laboratory scale the performance of eight different trapping solutions (water and sulfuric, phosphoric, nitric, carbonic, carbonic, acetic, citric, and maleic acids) at 25 and 2 °C. At 25 °C, the highest NH3 capture efficiency was achieved using strong acids (87% and 77% for sulfuric and nitric acid, respectively), followed by citric and phosphoric acid (65%) and water (62%). However, a remarkable improvement was observed for phosphoric acid (+15%), citric acid (+16%), maleic acid (+22%), and water (+12%) when the capture solution was at 2 °C. The economic analysis showed that water would be the cheapest option at any working temperature, with costs of 2.13 and 2.52 €/g N (vs. 3.33 and 3.43 €/g N for sulfuric acid) in the winter and summer scenarios, respectively. As for phosphoric and citric acid, they could be promising NH3 trapping solutions in the winter months, with associated costs of 3.20 and 3.96 €/g N, respectively. Based on capture performance and economic and environmental considerations, the reported findings support that water, phosphoric acid, and citric acid can be viable alternatives to the strong acids commonly used as NH3 adsorbents in these systems.

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20

Ha, Dong-Myeong, and Sungjin Lee. "Experimental Determination of Closed Cup Flash Point of Binary Flammable Solutions, 2-Propanol+Propionic acid and n-Hexanol+Formic Acid Solutions." Journal of the Korean Institute of Gas 19, no. 3 (June 28, 2015): 18–24. http://dx.doi.org/10.7842/kigas.2015.19.3.18.

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21

Eliseeva, Tatiana, and Anastasiia Kharina. "Desalination of Neutral Amino Acid Solutions in an Electromembrane System." Membranes 12, no. 7 (June 28, 2022): 665. http://dx.doi.org/10.3390/membranes12070665.

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This article’s main focus is to highlight significant aspects of amino acid solution demineralization. The main part of the amino acid production method requires the provision of downstream treatment solutions for the process of desalination. Electrodialysis (ED) and electrodeionization (EDI) are prospective technologies for such treatment. The article presents a brief review of the first studies and current research on electromembrane desalination of amino acid solutions as well as the analysis of some electrochemical features for the mineral salt–amino acid system (model solution) in an ED process based on the experimental results. The influence of various factors on the desalination of neutral amino acid-containing solutions and on target product losses in this process is estimated. The behavior of aliphatic (alanine) and aromatic (phenylalanine) amino acids in the electromembrane system is considered in mixed solutions with inorganic electrolytes. The influence of various mineral cations (Na+, K+ and NH4+) and anions (NO3−, SO42−, Cl−) on the features of the transport and current–voltage characteristics of ion-exchange membranes in the electrodialysis of phenylalanine- and alanine-containing solutions is considered. A comparative analysis of the desalination parameters of AA solutions in electrodialysis with the following pairs of heterogeneous MA-41/MK-40, MA-40/MK-40 and homogeneous AMT/CMT membranes is carried out. The minimum amount of amino acid loss along with rather high values of the degree of desalination are revealed in electrodialysis with polypropylene spacers in comparison with EDI, ED with a copolymer of styrene and divinylbenzene as spacer, as well as ED with a smooth deionization channel. At the same time, EDI is the most promising method to reach the highest desalination degree in the considered range of mineral salt content.

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Robert, L., J. Mourgues, Arlette Pamar-Robert, D. Achour, and J. Molinier. "Adsorption of tartaric acid and malic by active carbons." OENO One 29, no. 1 (March 31, 1995): 49. http://dx.doi.org/10.20870/oeno-one.1995.29.1.1719.

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<p style="text-align: justify;">Adsorption of tartaric acid and malic acid by active carbons bas been tested with six samples of carbons. At acid pH ; the adsorbed amounts of tartaric acid and of malic acid are practically the same. For a solution concentration of 20 g/l, adsorbed amounts from 0.008 to 0.29 gramme for one gramme of carbon have been found, variation which may be due to various states of carbon surface oxidation. Increasing the pH of the solutions shows a dramatic decrease of adsorbed amounts, this decrease being more rapid for tartaric acid than for malic acid. At neutral pH, the adsoiption becomes negligible. With acidic solutions containing the two acids altogether, acid malic is more adsorbed than tartaric acid.</p>

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Guo, Hou-Fei, Hsiu-Li Lin, and T. Leon Yu. "DILUTE SOLUTION PROPERTIES OF CHITOSAN IN PROPIONIC ACID AQUEOUS SOLUTIONS." Journal of Macromolecular Science, Part A 39, no. 8 (July 31, 2002): 837–52. http://dx.doi.org/10.1081/ma-120005804.

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24

Münchow, Eliseu A., Ana Cláudia A. Ferreira, Raissa M. M. Machado, Tatiana S. Ramos, Sinval A. Rodrigues-Junior, and Cesar H. Zanchi. "Effect of Acidic Solutions on the Surface Degradation of a Micro-Hybrid Composite Resin." Brazilian Dental Journal 25, no. 4 (2014): 321–26. http://dx.doi.org/10.1590/0103-6440201300058.

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Composite resins may undergo wear by the action of chemical substances (e.g., saliva, alcohol, bacterial acids) of the oral environment, which may affect the material's structure and surface properties. This study evaluated the effect of acidic substances on the surface properties of a micro-hybrid composite resin (Filtek Z-250). Eighty specimens were prepared, and baseline hardness and surface roughness (KMN0 and Ra0, respectively) were measured. The specimens were subjected to sorption (SO) and solubility (SL) tests according to ISO 4049:2009, but using different storage solutions: deionized water; 75/25 vol% ethanol/water solution; lactic acid; propionic acid; and acetic acid. The acids were used in two concentrations: PA and 0.02 N. pH was measured for all solutions and final hardness (KMN1) and surface roughness (Ra1) were measured. Data were analyzed with paired t-tests and one-way ANOVA and Tukey's test (a=5%). All solutions decreased hardness and increased the Ra values, except for the specimens stored in water and 0.02 N lactic acid, which maintained the hardness. All solutions produced similar SO and SL phenomena, except for the 0.02 N lactic acid, which caused lower solubility than the other solutions. Ethanol showed the highest pH (6.6) and the 0.02 N lactic acid the lowest one (2.5). The solutions affected negatively the surface properties of the composite resin; in addition, an acidic pH did not seem to be a significant factor that intensifies the surface degradation phenomena.

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25

Saad-Hossne, Rogério, René Gamberini Prado, and William Saad Hossne. "Effects of acetylsalicylic acid and acetic acid solutions in VX2 carcinoma cells: In vitro analysis." Acta Cirurgica Brasileira 21, no. 3 (June 2006): 151–54. http://dx.doi.org/10.1590/s0102-86502006000300006.

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Анотація:

PURPOSE: To analyze, in vitro, the effects of acetylsalicylic acid (aspirin) and acetic acid solutions on VX2 carcinoma cells in suspension and to examine the correlation between these effects and neoplastic cell death. METHODS: The VX2 tumor cells (10(7) cells/ml) were incubated in solutions containing differing concentrations (2.5% and 5%) of either acetylsalicylic acid or acetic acid, or in saline solution (controls). Every five minutes, cell viability was tested (using the trypan blue test) and analyzed under light microscopy. RESULTS: Tumor cell viability (in %) decreased progressively and, by 30 minutes, neoplastic cell death had occurred in all solutions. CONCLUSION: Based on this experimental model and the methodology employed, we conclude that these solutions cause neoplastic cell death in vitro.

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26

Brawley, Vince, Jatinder Bhatia, and Warren B. Karp. "Hydrogen Peroxide Generation in a Model Paediatric Parenteral Amino Acid Solution." Clinical Science 85, no. 6 (December 1, 1993): 709–12. http://dx.doi.org/10.1042/cs0850709.

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Анотація:

1. Parenteral amino acid solutions undergo photo-oxidation, which may be an important factor in total parenteral nutrition-associated hepatic dysfunction. Light-exposed parenteral solutions containing amino acids, in addition to vitamins and trace minerals, generate free radicals, which, in turn, may contribute to this type of injury. This study examined the characteristics of H2O2 production in a parenteral amino acid solution modelled on a commercially available paediatric parenteral amino acid solution. 2. The solution was exposed to light in the presence of riboflavin-5′-monophosphate (riboflavin), and peroxide formation in the presence and absence of catalase (H2O2 formation) was assayed using potassium iodide/molybdate. 3. Peak H2O2 production occurred at a light intensity of 8 μW cm−2 nm−1 in the 425–475 nm waveband and was linear to 2 h of light exposure. H2O2 production reached 500 μmol/l at 24 h. 4. H2O2 was directly related to a riboflavin concentration of up to 20 μmol/l and was maximal at 30 μmol/l. 5. H2O2 production was greatest in the amino acid/riboflavin solution at a pH of between 5 and 6. 6. Under the conditions of light exposure intensity, light exposure time, riboflavin concentration and pH found during the administration of parenteral nutrition in neonatal intensive care units, net H2O2 production occurs in solutions modelled on a paediatric parenteral amino acid preparation.

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27

Horkay, Ferenc, Peter J. Basser, David J. Londono, Anne-Marie Hecht, and Erik Geissler. "Ions in hyaluronic acid solutions." Journal of Chemical Physics 131, no. 18 (November 14, 2009): 184902. http://dx.doi.org/10.1063/1.3262308.

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28

Logan, Norman. "Chemistry in nitric acid solutions." Pure and Applied Chemistry 58, no. 8 (January 1, 1986): 1147–52. http://dx.doi.org/10.1351/pac198658081147.

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29

Kreuz, John A. "Hydrolyses of polyamic-acid solutions." Journal of Polymer Science Part A: Polymer Chemistry 28, no. 13 (December 1990): 3787–93. http://dx.doi.org/10.1002/pola.1990.080281321.

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30

Petrukhina, Vera A., Pavel I. Fedorov, Tatiana A. Kirillova, Ludmila Yu Tcareva, Ekterina V. Andreeva, and Nikolay I. Koltsov. "Study of the effect of temperature on the electrical conductivity of aqueous solutions of amino acids." Butlerov Communications 57, no. 1 (January 31, 2019): 91–94. http://dx.doi.org/10.37952/roi-jbc-01/19-57-1-91.

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Анотація:

It is well-known fact that water is a universal solvent due to its physicochemical properties and dielectric constant. Therefore, the majority of substances with a crystalline structure and the structure close to it are well soluble in water due to the dissociation of molecules into ions. Amino acids are organic ampholytes – substances capable of being in ionic forms in water. The quantitative and qualitative composition of ampholytes depends on the structure and composition of amino acids and pH of solution. The interaction of amino acid ions in solution with hydrogen ions and hydroxyl leads to the formation of complex cations and anions. The presence of amino and carboxyl groups in amino acid molecules contributes to the formation of inter-ion positively and negatively charged complexes which leads to the decrease in their mobility and electrical conductivity of solutions. It is observed with increasing concentration of amino acid solutions. The conductivity of amino acid solutions is also influenced by temperature which has a non-linear relationship. We have proposed the approach based on studying the effect of temperature on the equivalent electrical conductivity at infinite dilution λ∞ and describing the experimental data λ∞(Т) by the exponential Arrhenius equation. This article studies the possibility of describing the experimental data λ∞(Т) for aqueous solutions of a number of amino acids by this equation. It is shown that the Arrhenius equation with the found activation energy values adequately describes the dependences of limiting equivalent conductivity on temperature for aqueous solutions of valine, leucine, isoleucine, threonine, lysine, methionine, phenylalanine, L-aspartic and D-aspartic acids, histidine, arginine.

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31

Liu, Jun Xia, Bing Zhi Dong, Yun Ge Sheng, and Ji Ping Wang. "Identifying Membrane Foulants in Chemical Cleaning Solutions." Advanced Materials Research 726-731 (August 2013): 1872–78. http://dx.doi.org/10.4028/www.scientific.net/amr.726-731.1872.

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The main objective of this study was to investigate foulants in chemical cleaning solutions of membrane (CCSM). Sodium hydroxide (NaOH), sodium hypochlorite (NaOCl), hydrochloric acid (HCl) were used as chemical agents respectively. Hydrophobicity, molecular weight distribution and metal ions of foulants in CCSM were analyzed as the major characters for membrane fouling. Results reveal that alkali cleaning can remove both hydrophobic and hydrophilic fractions of natural organic matters (NOM), and acid cleaning mainly removes hydrophilic organic matters. Medium molecular weight of very hydrophobic acids (1-10 kDa) and different molecular weight of neutral hydrophilic acids (100-1000 Da & >300kDa) in NOM can lead to membrane irreversible fouling. Acid cleaning is relatively effective for the reduction of inorganic foulants. The main metal ions in acid cleaning solutions are K ,Ca, Al and Mn, which are responsible for membrane inorganic fouling.

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32

Djokić, Stojan. "Synthesis and Antimicrobial Activity of Silver Citrate Complexes." Bioinorganic Chemistry and Applications 2008 (2008): 1–7. http://dx.doi.org/10.1155/2008/436458.

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Анотація:

Formation of silver citrate/citric acid complexed solutions was investigated. Although, silver citrate is minimally soluble in water, it can successfully be dissolved in citric acid solutions. The maximum concentration of Ag(I) in solution is estimated at 23 to 25 g/L if the concentration of citric acid is at least 4 mol/L or higher. The dissolution of silver citrate in citric acid solutions was attributed to the formation of silver citrate complexes of a general formula[Ag3(C6H5O7)n+1]3n−. The silver citrate/citric acid solutions, containing more than about 13 g/LAg+ion, have exhibited a decrease in Ag(I) concentration in solution over time, due to crystallization. The crystallization product was attributed to the formation of[Ag3C6H5O7]x⋅nH2O. Importantly, the diluted silver citrate/citric acid complexed solutions have exhibited very strong bacteriostatic and bactericidal activities.

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33

Turek, Piotr, Tomasz Bajda, and Maciej Manecki. "Dissolution of mimetite Pb5(AsO4)3Cl in malic acid solutions." Mineralogia 45, no. 1-2 (June 1, 2015): 3–12. http://dx.doi.org/10.2478/mipo-2014-0001.

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Abstract Mimetite Pb5(AsO4)3Cl is the most insoluble lead arsenate mineral and could be used in remediation techniques to reduce As(V) mobility in soils. However, low-molecular-weight organic acids such as malic acid increase its solubility. The effect of malic acid on the dissolution of mimetite strongly depends on the pH of the equilibrium solution. At low pH, mimetite is decomposed mostly by the mechanism of protonation. With increasing pH, the solubility of mimetite decreases and a greater influence in its dissolution is ascribed to complexation of Pb(II) by organic ligands. During dissolution experiments, the amount of arsenic released to solution was > 26% higher in organic solutions than in inorganic solutions, and the amount of lead was > 8% greater. The solubility product of mimetite (KSP) was calculated in order to quantify the thermodynamic stability of the investigated mineral. The value obtained, i.e., -24.52 ± 0.49 fluctuates between the values of -21.69 ± 1.05 and -27.87 ± 0.42 reported in the literature.

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34

Li, Yonggang, Yinghui Wei, and Shengqiang Yang. "De-alloying Behavior of Mg–Al alloy in Sulphuric Acid and Acetic Acid Aqueous Solutions." Materials 12, no. 13 (June 26, 2019): 2046. http://dx.doi.org/10.3390/ma12132046.

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Анотація:

The fabricated Mg–Al alloy consists of α-Mg phase and Mg–Mg17Al12 eutectic phase. The corrosion behavior of cast Mg–Al alloy in sulphuric acid (H2SO4) and acetic acid (HAc) aqueous solutions was investigated. The Mg–Al alloy shows general corrosion in H2SO4 solution, and the α-Mg dendrites revealed a slightly faster corrosion rate than that of the eutectics. In HAc solution, the alloy shows an obvious selective corrosion characteristic, with the α-Mg dendrites being corroded preferentially. Grain orientation plays an important role in corrosion behavior of the alloy in the HAc solutions.

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35

Burlakova, V. E., and E. G. Drogan. "Effect of organic acid concentration in lubricant on tribological characteristics of friction couple." Vestnik of Don State Technical University 19, no. 1 (April 1, 2019): 24–30. http://dx.doi.org/10.23947/1992-5980-2019-19-1-24-30.

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Introduction.The possibility of using monocarboxylic acids as a lubricant composition additive, and the effect of their concentration in lubricant on the evolution of the friction factor of a brass-steel couple, as well as the morphology of the film surface under friction is considered. The work objective is to study the effect of the concentration of carboxylic acids in the lubricant composition on the evolution of the friction factor of copper – steel alloy.Materials and Methods.Tribological studies of a brass-steel friction couple in aqueous solutions of monocarboxylic acids with the concentrations of 0.025; 0.05; 0.1; 0.2; 0.5 mol/l are carried out. Using scanning electron microscopy, we have studied the morphology of the servovite film surface that is formed on a steel disk after frictional interaction of a brasssteel couple in aqueous solutions of acids with the concentration of 0.1 mol/l.Research Results.Tribological characteristics of the brasssteel tribocoupling in aqueous solutions of carboxylic acids of various concentrations are studied. The optimum acid concentration in the lubricant composition is specified. Herewith, a selective transfer and a wearless friction regime are implemented under friction of the brass 59–steel 40X couple. A decrease in the friction ratio to 0.009 and 0.007 is found out under friction in aqueous solutions of valeric and caproic acids, respectively. The formation of an anti-friction film on the steel surface is identified through the scanning electron microscopy. It is established that the film formed in an aqueous solution of caproic acid has a denser structure in comparison with the film formed under friction in aqueous solutions of butyric and caproic acids.Discussion and Conclusions.Thus, the tribological studies of a brass-steel friction couple in aqueous acid solutions show that the optimum molar acid concentration in the lubricant composition is 0.1 mol/l. At this acid concentration, the values of the friction factor characteristic of the wearless mode are attained.

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36

Chashchin, I. S., M. S. Rubina, N. A. Arkharova, and M. A. Pigaleva. "Microstructure and Mechanical Strength Properties of Chitosan Sponges Obtained from Polymer Solutions in Carbonic Acid." Polymer Science, Series A 63, no. 6 (November 2021): 749–56. http://dx.doi.org/10.1134/s0965545x21060018.

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Abstract Polymer sponges based on chitosan are first obtained from chitosan solutions in carbonic acid and gels based on these solutions crosslinked by a noncytotoxic agent of natural origin, genipin. A comparative analysis of the structure and mechanical strength properties of sponges prepared from chitosan solutions in carbonic and acetic acids is carried out. It is shown that the addition of genipin in an amount of ~2 wt % to a chitosan solution in carbonic acid leads to a decrease in the average pore size by ~2.5 times and a significant increase in the strength characteristics of the material in comparison with the sponge prepared without genipin.

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37

Keeffe, J. R., A. J. Kresge, and J. Toullec. "Acid-catalyzed enolization of acetophenone: catalysis by bisulfate ion in sulfuric acid solutions." Canadian Journal of Chemistry 64, no. 6 (June 1, 1986): 1224–27. http://dx.doi.org/10.1139/v86-203.

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Rates of acid-catalyzed enolization of acetophenone in dilute aqueous solution, measured under conditions where the solvated proton is the only acidic species present, give a hydrogen ion catalytic coefficient, [Formula: see text], that is 35% smaller than the value obtained by X acidity function extrapolation of measurements made in moderately concentrated sulfuric acid solutions. The difference may be attributed to catalysis by bisulfate ion in the sulfuric acid solutions; this is supported by direct measurement of the bisulfate ion catalytic coefficient in dilute sulfuric acid. This revised value of [Formula: see text] leads to new, but only slightly different, values of the keto–enol equilibrium constant for acetophenone in aqueous solution, pKE = 7.96 ± 0.04, the acidity constant for acetophenone ionizing as a carbon acid, [Formula: see text] and the encounter-controlled rate constant for the reaction of acetophenone enol with molecular bromine, k = (3.2 ± 0.4) × 109 M−1 s−1.

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38

Jankovska, Katica, Lidija Soptrajanova, and Ilinka Spirevska. "Protonation of maleic and fumaric acid in aqueous sulfuric acid solutions." Journal of the Serbian Chemical Society 65, no. 10 (2000): 695–708. http://dx.doi.org/10.2298/jsc0010695j.

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The protonations of maleic and fumaric acid in an acidic medium (aqueous solutions of sulfuric acid) were followed spectrophotometrically at room temperature. The acid-base equilibria were characterised qualitatively and quantitatively. The pKBH+ values were determined using the Hammett equation, employing several acid functions in order to determine which of them describes best the protonation process of the studied organic acids. The thermodynamic pKBH+ values as well as those of the solvation parameters m, m* and ? and of the thermodynamic protonation constants (or, rather, the pKa,p values) were also defermined. The method of characteristic vector analysis (CVA) was used to reconstruct the experimental spectra.

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39

Christensen, Michael L., Julienne Burgess, Richard A. Helms, Joseph Mirro, David K. Kalwinsky, and Michael C. Storm. "Plasma Amino Acids in Patients with Acute Nonlymphocytic Leukemia Receiving Parenteral Nutrition." Annals of Pharmacotherapy 27, no. 2 (February 1993): 146–50. http://dx.doi.org/10.1177/106002809302700201.

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Objective To assess the effect of parenteral amino acid solutions on plasma amino acid concentrations in patients with acute nonlymphocytic leukemia (ANLL) receiving parenteral nutrition (PN). Design Ten patients were studied at diagnosis, on the morning PN was started, and three times during PN therapy coinciding with the sequential administration of three different amino acid solutions (Aminosyn, FreAmine HBC, and TrophAmine). The order of amino acid solution administration in each patient was by a randomized, block design. Results The patients were undergoing identical intensive induction therapy. There was no significant difference in the number of days they received PN or the amount of protein or calories received during the three PN study periods. At diagnosis, phenylalanine and glutamic acid concentrations were elevated compared with previously published normal values and remained elevated at all observation times. During PN, asparagine, aspartic acid, and tyrosine concentrations were significantly lower with all three amino acid solutions compared with their concentrations at diagnosis. Glycine and threonine concentrations were also significantly lower with FreAmine HBC and TrophAmine administration and cysteine concentrations were significantly lower with FreAmine HBC administration than at the time of diagnosis. Aminosyn was associated with plasma amino acid concentrations most similar to those measured at diagnosis. Conclusions These results indicate that most amino acid concentrations fall within the normal range at diagnosis in the ANLL patients studied. Plasma concentrations for certain amino acids can be influenced by the amino acid solution used in PN. Further understanding of the derangements in amino acid metabolism and the influence of parenterally administered amino acid solutions on plasma amino acid concentrations may lead to improvements in the nutritional support of cancer patients.

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40

Skvortsov, Alexey, Ekaterina Babich, Andrey Lipovskii, Alexey Redkov, Guang Yang, and Valentina Zhurikhina. "Raman Scattering Study of Amino Acids Adsorbed on a Silver Nanoisland Film." Sensors 22, no. 14 (July 21, 2022): 5455. http://dx.doi.org/10.3390/s22145455.

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Анотація:

We studied the surface-enhanced Raman spectra of amino acids D-alanine and DL-serine and their mixture on silver nanoisland films (SNF) immersed in phosphate-buffered saline (PBS) solution at millimolar amino acid concentrations. It is shown that the spectra from the amino acid solutions differ from the reference spectra for microcrystallites due to the electrostatic orientation of amino acid zwitterions by the metal nanoisland film. Moreover, non-additive peaks are observed in the spectrum of the mixture of amino acids adsorbed on SNF, which means that intermolecular interactions between adsorbed amino acids are very significant. The results indicate the need for a thorough analysis of the Raman spectra from amino acid solutions, particularly, in PBS, in the presence of a nanostructured silver surface, and may also be of interest for studying molecular properties and intermolecular interactions.

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41

Vazquez, J. A., E. L. Morse, and S. A. Adibi. "Effect of starvation on amino acid and peptide transport and peptide hydrolysis in humans." American Journal of Physiology-Gastrointestinal and Liver Physiology 249, no. 5 (November 1, 1985): G563—G566. http://dx.doi.org/10.1152/ajpgi.1985.249.5.g563.

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Jejunal disappearance rates of glycine (a model for neutral amino acid absorption), triglycine (a model for peptide transport), and tetraglycine (a model for brush-border membrane hydrolysis) were investigated by an in situ perfusion technique before and after 2 wk of starvation in seven obese volunteers. The three test solutions of glycine, triglycine, and tetraglycine were equivalent in glycine content. Before starvation glycine absorption was greatest from the triglycine solution and smallest from the glycine solution. Starvation significantly decreased glycine absorption from both glycine and triglycine solutions, but not from the tetraglycine solution. However, glycine absorption was still significantly greater from the triglycine and tetraglycine solutions than from the glycine solution. Starvation had no significant effect on the disappearance rate of triglycine, but it increased the disappearance rate of tetraglycine. We conclude that a) starvation has different effects on functions of mucosal brush-border membrane, for example, it reduces amino acid absorption but enhances peptide hydrolysis; and b) the greater amino acid absorption from peptides is maintained even after 2 wk of starvation, suggesting that peptides are superior to free amino acids as the nitrogen source for enteral nutrition if employed in malnutrition.

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42

IJmker, H. M., M. Gramblička, S. R. A. Kersten, A. G. J. van der Ham, and B. Schuur. "Acetic acid extraction from aqueous solutions using fatty acids." Separation and Purification Technology 125 (April 2014): 256–63. http://dx.doi.org/10.1016/j.seppur.2014.01.050.

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43

Hluchan, V., B. L. Wheeler, and N. Hackerman. "Amino acids as corrosion inhibitors in hydrochloric acid solutions." Materials and Corrosion/Werkstoffe und Korrosion 39, no. 11 (November 1988): 512–17. http://dx.doi.org/10.1002/maco.19880391106.

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44

Feriani, Mariano, Claudio Ronco, and Giuseppe La Greca. "Acid-Base Balance with Different Capd Solutions." Peritoneal Dialysis International: Journal of the International Society for Peritoneal Dialysis 16, no. 1_suppl (January 1996): 126–29. http://dx.doi.org/10.1177/089686089601601s23.

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Our objective is to investigate transperitoneal buffer fluxes with solution containing lactate and bicarbonate, and to compare the final effect on body base balance of the two solutions. One hundred and four exchanges, using different dwell times, were performed in 52 stable continuous ambulatory peritoneal dialysis (CAPD) patients. Dialysate effluent lactate and bicarbonate and volumes were measured. Net dialytic base gain was calculated. Patients’ acid-base status and plasma lactate were determined. In lactate-buffered CAPD solution, lactate concentration in dialysate effluent inversely correlated with length of dwell time, but did not correlate with plasma lactate concentration and net ultrafiltration. Bicarbonate concentration in dialysate effluent correlated with plasma bicarbonate and dwell time but not with ultrafiltration. The arithmetic sum of the lactate gain and bicarbonate loss yielded the net dialytic base gain. Ultrafiltration was the most important factor affecting net dialytic base gain. A previous study demonstrated that in patients using a bicarbonate-buffered solution the net bicarbonate gain is a function of dwell time, ultrafiltration, and plasma bicarbonate. By combining the predicted data of the dialytic base gain with the calculated metabolic acid production, an approximate body base balance could be obtained with both lactate and bicarbonate-buffered CAPD solutions. The body base balance in CAPD patients is self-regulated by the feedback between plasma bicarbonate concentration and dialytic base gain. The level of plasma bicarbonate is determined by the dialytic base gain and the metabolic acid production. This can explain the large interpatient variability in acid-base correction. Bicarbonate-buffered CAPD solution is equal to lactate solution in correcting acid-base disorders of CAPD patients.

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45

Ogiso, Kazuma, Yasutake Shimizu, Ken Watanabe, and Keiichi Tonosaki. "Possible Involvement of Undissociated Acid Molecules in the Acid Response of the Chorda Tympani Nerve of the Rat." Journal of Neurophysiology 83, no. 5 (May 1, 2000): 2776–79. http://dx.doi.org/10.1152/jn.2000.83.5.2776.

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To test whether undissociated acid is capable of exciting the chorda tympani nerves in rats, we have used buffered acid solutions as taste stimuli. These solutions were prepared by adding alkali to weak acids, such as acetic acid, so that the proportion of undissociated and dissociated acids was varied whereas keeping the total acid concentration constant. When acetic acid solutions, adjusted to wide ranges of pH by NaOH, were applied to the tongue, the response magnitude of the chorda tympani nerves was not varied systematically with pH changes. However, if the sodium effect was eliminated by amiloride or replacement of cation by potassium or Tris[hydroxymethyl]aminomethane; NH2C(CH2OH)3 (Tris-base), the chorda tympani response was reduced systematically as pH increased. Similar results were obtained with citric acid and ascorbic acid. This pH-dependent change in taste nerve response to acid cannot be solely attributed to the proton gradient because the response magnitude induced by hydrogen itself, which was estimated from responses to strong acids, was much smaller than that by equi-pH acetic acid (∼85%). Thus we cannot explain the pH-dependent responses of the chorda tympani nerves to weak acids unless effects of undissociated acid molecules are postulated. It is therefore concluded that undissociated acids in weak acid solutions can be a stimulant to taste receptor cells.

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46

Varga, Z., G. Kiss, and H. C. Hansson. "Modelling the cloud condensation nucleus activity of organic acids on the basis of surface tension and osmolality measurements." Atmospheric Chemistry and Physics 7, no. 17 (September 7, 2007): 4601–11. http://dx.doi.org/10.5194/acp-7-4601-2007.

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Анотація:

Abstract. In this study vapour pressure osmometry was used to determine water activity in the solutions of organic acids. The surface tension of the solutions was also monitored in parallel and then Köhler curves were calculated for nine organic acids (oxalic, malonic, succinic, glutaric, adipic, maleic, malic, citric and cis-pinonic). Surface tension depression is negligible for most of the organic acids in dilute (≤1 w/w%) solutions. Therefore, these compounds affect equilibrium vapour pressure only in the beginning phase of droplet formation when the droplet solution is more concentrated but not necessarily at the critical size. An exception is cis-pinonic acid which remarkably depress surface tension also in dilute (0.1 w/w%) solution and hence at the critical point. The surface tension of organic acid solutions is influenced by the solubility of the compound, the length of the carbon chain and also by the polar functional groups present in the molecule. Similarly to surface tension solubility plays an important role also in water activity: compounds with higher solubility (e.g. malonic, maleic and glutaric acid) reduce water activity significantly in the early phase of droplet formation while less soluble acids (e.g. succinic and adipic acid) are saturated in small droplets and the solution starts diluting only in bigger droplets. As a consequence, compounds with lower solubility have a minor effect on water activity in the early phase of droplet formation. To deduce the total effect Köhler curves were calculated and critical supersaturations (Sc) were determined for the organic acids using measured surface tension and water activity. It was found that critical supersaturation grew with growing carbon number. Oxalic acid had the lowest critical supersaturation in the size range studied and it was comparable to the activation of ammonium sulphate. The Sc values obtained in this study were compared to data from CCNC experiments. In most cases good agreement was found. For modelling purposes Sc vs. ddry plots are given and the dependence of water activity and surface tension on concentration are also formulated.

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47

Sadyrbaeva, Tatiana. "Liquid Membrane System for Extraction and Electrodeposition of Copper(II)." Key Engineering Materials 850 (June 2020): 22–27. http://dx.doi.org/10.4028/www.scientific.net/kem.850.22.

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Анотація:

The extraction of copper (II) ions using di (2-ethylhexyl) phosphoric acid – based liquid membranes during a galvanostatic electrodialysis-electrolysis process was studied. Effects of the current density, copper (II) and hydrochloric acid concentration in the feed solution, carrier and admixture concentration in the liquid membrane, type of acid in the catholyte were studied, and the optimal conditions were determined. A practically complete removal of copper (II) from the feed solution containing 0.01 M CuCl2 was achieved during 3.0 −4.0 h of electrodialysis. A possibility of effective transfer and electrodeposition of copper (II) from dilute solutions of sulfuric, hydrochloric, perchloric, nitric and acetic acids was shown. Adherent copper coatings with a fine-grained structure were obtained from dilute sulfuric acid solutions. A maximum stripping degree into the catholyte of 88 % and an electrodeposition degree of 73 % were achieved in the studied system.

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48

Klaviņš, Māris, and Oskars Purmalis. "Surface Activity of Humic Acids Depending on Their Origin and Humification Degree." Proceedings of the Latvian Academy of Sciences. Section B. Natural, Exact, and Applied Sciences. 67, no. 6 (July 17, 2014): 493–99. http://dx.doi.org/10.2478/prolas-2013-0083.

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Abstract Humic substances are able to reduce the surface tension of their solutions and thus can act as surface-active substances in the natural environment, which may have industrial application. The ability to influence the surface tension of humic acid solutions depends on the origin of the humic acids. The objective of this study was comparison of the ability of humic acids of different origin (soil, water, peat, lignite etc.) to influence the surface tension of their solutions, and identification of the structural characteristics of peat humic acids that determine their surfactant properties. Industrially produced humic materials demonstrated no or insignificant impact on the surface tension of their solutions. However, humic acids isolated from peat had significant impact of the surface tension of their solutions, acting as weak surfactants. The surface tension of humic acid solutions decreased with increasing concentration, and depended on solution pH. Using a well-characterised bog profile, the ability to influence the surface tension of peat humic acids was shown to depend on age and humification degree. With increase of the humification degree and age, molecular complexity of humic acids and their ability to influence surface tension decreased; but nevertheless, the impact of the biological precursor (peat-forming bryophytes and plants) could be identified.

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49

Song, Si Jeong, Viet Nhan Hoa Nguyen, and Man Seung Lee. "Recovery of Palladium Metal with High Purity by Selective Reduction from Inorganic Acid Leaching Solutions of Cemented Zinc." Korean Journal of Metals and Materials 60, no. 11 (November 5, 2022): 837–44. http://dx.doi.org/10.3365/kjmm.2022.60.11.837.

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A small amount of Pd(II) present in spent electroplating solutions is concentrated by cementation. In this work, a process was developed to recover pure palladium metal by selective reduction from the hydrochloric and the sulfuric acid leaching solutions of cemented zinc. For this purpose, hydrazine and ascorbic acid were employed as reducing agents and the effect of several variables such as the acidity of the leaching solutions, molar ratio of reducing agents to Pd(II), reaction time and temperature was investigated. Since neither of the reducing agents can reduce Pd(II) from strong acidic solutions, it was necessary to decrease the acidity of the leaching solutions by dilution with distilled water. Our results indicated that it was possible to recover Pd metal with high purity by selective reduction after diluting the hydrochloric and sulfuric acid leaching solutions of cemented zinc with distilled water. When the molar ratios of the reducing agents to Pd(II) were the same, the reduction percentage of Pd(II) from the sulfuric acid solution was higher than that from the hydrochloric acid solution, due to the much higher complex formation constant of PdCl42- than Pd(SO4)22-. The reduction of Pd(II) by hydrazine occurred within 15 mins at room temperature, while a higher temperature (60 oC) and longer reaction time (1h) were necessary to reduce Pd(II) with ascorbic acid. The reduction of Pd(II) from sulfuric acid solution was more efficient than from hydrochloric acid solution. It was possible to recover Pd metal with high purity from the leaching solution of cemented zinc using the reduction method.

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50

Song, Jin Feng, Hai Yun Qi, Xiao Yang Cui, and Hong Mei Peng. "Effects of Organic Acids on Chlorophyll Contents and Photosynthesis of Fraxinus mandshurica Seedlings." Advanced Materials Research 393-395 (November 2011): 713–16. http://dx.doi.org/10.4028/www.scientific.net/amr.393-395.713.

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By simulating oxalic and citric acid concentrations in forest litter leachates,a series of experiments were conducted to study the effects of oxalic acid and citric acid solutions on chlorophyll contents and photosynthesis of Fraxinus mandshurica seedlings.It resulted that, organic acids of appropriate concentrations increased chlorophyll contents, chlorophyll a and chlorophyll b contents varied more than carotenoid content, and 1.0mmol/L solution was best. To photosynthesis, the variability treads of net photosynthetic rates with organic acids were probably consistent to those with distilled water, but the values all increased, and 5.0mmol/L solution was best. Effects of different organic acids on chlorophyll contents and photosynthesis followed the series: citric acid >oxalic acid, and it might be relative to chemical structure, dissociation constants and organic ligand-metal stabilities of two kinds of organic acids.

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