Carbonate-bicarbonate Buffer Research Articles

Chemical state of nickel nanoparticles during the oxygen evolution reaction in a carbonate-bicarbonate buffer solution

Chemical state of nickel nanoparticles during the oxygen evolution reaction in a carbonate-bicarbonate buffer solution

Intrafibrillar mineralization of type I collagen with calcium carbonate and strontium carbonate induced by polyelectrolyte-cation complexes.

Calcium carbonate (CaCO3), possessing excellent biocompatibility, bioactivity, osteoconductivity and superior biodegradability, may serve as an alternative to hydroxyapatite (HAp), the natural inorganic component of bone and dentin. Intrafibrillar mineralization of collagen with CaCO3 was achieved through the polymer-induced liquid precursor (PILP) process for at least 2 days. This study aims to propose a novel pathway for rapid intrafibrillar mineralization with CaCO3 by sequential application of the carbonate-bicarbonate buffer and polyaspartic acid (pAsp)-Ca suspension. Fourier transform infrared (FTIR) spectroscopy, zeta potential measurements, atomic force microscopy/Kelvin probe force microscopy (AFM/KPFM), and three-dimensional stochastic optical reconstruction microscopy (3D STORM) demonstrated that the carbonate-bicarbonate buffer significantly decreased the surface potential of collagen and CO32-/HCO3- ions could attach to collagen fibrils via hydrogen bonds. The electropositive pAsp-Ca complexes and free Ca2+ ions are attracted to and interact with CO32-/HCO3- ions through electrostatic attractions to form amorphous calcium carbonate that crystallizes gradually. Moreover, like CaCO3, strontium carbonate (SrCO3) can deposit inside the collagen fibrils through this pathway. The CaCO3-mineralized collagen gels exhibited better biocompatibility and cell proliferation ability than SrCO3. This study provides a feasible strategy for rapid collagen mineralization with CaCO3 and SrCO3, as well as elucidating the tissue engineering of CaCO3-based biomineralized materials.

Structure and Properties of Gelatin Methacryloyl (GelMA) Synthesized in Different Reaction Systems.

Gelatin methacryloyl (GelMA) hydrogels have been extensively used for drug delivery and tissue engineering applications due to their good biocompatibility, biodegradability, and controllable photocurable efficiency. Phosphate buffer solution (PBS) is the most widely used reaction system for GelMA synthesis. However, carbonate-bicarbonate buffer solution (CBS) has been tried recently for synthesizing GelMA due to its high reaction efficiency. However, there is a lack of systematic investigation into possible differences in the structure and properties of GelMA synthesized in PBS and CBS, respectively. Therefore, in the current study, GelMA molecules with two degrees of methacryloylation (∼20 and ∼80%) were synthesized under PBS and CBS reaction systems, respectively, in comparable conditions. The results showed that because of the functionalization of methacrylate groups in gelatin chains, which could interfere with the intrachain and interchain interactions, such as hydrogen bonding, the GelMA molecules synthesized in PBS had distinct physical structures and exhibited different properties in comparison with those produced in CBS. GelMA hydrogels synthesized in PBS exhibited higher gel-sol transition temperatures and better photocurable efficiencies, mechanical strength, and biological properties. In contrast, GelMA hydrogels produced in CBS showed advantages in swelling performance and microstructures, such as pore sizes and porosities. In addition, GelMA synthesized in PBS and possessing a high degree of methacryloylation (the "GelMA-PH" polymer) showed great potential for three-dimensional (3D) bioprinting. This focused study has gained helpful new insights into GelMA and can provide guidance on the application of GelMA in 3D printing and tissue engineering.

Selective H2S Absorption Using the Mixture of NaOH-NaHCO3-Na2CO3 Buffer Solvent Solution

Acid gas enrichment unit (AGEU) involves selective separation of H2S from acid gas mixture, for example using absorption with an NaOH solvent solution. Sodium carbonate (Na2CO3) and sodium bicarbonate (NaHCO3) buffer addition to NaOH solution suppresses CO2 absorption, thereby increasing the selectivity of H2S absorption. This study evaluated the effect of buffer addition to increase H2S absorption selectivity using an NaOH solution. It was shown that both buffer addition and L/G ratio decrease could increase H2S selectivity by limiting CO2 absorption. Based on the simulation results, in the 0.006 to 0.030 L/G ratio range and NaOH solvent concentration greater than 2%-mass, the addition of NaHCO3 with mass ratio greater than 1.5:1 to NaOH and the addition of Na2CO3 at 1.26 times NaHCO3’s mass increased H2S absorption selectivity up to 17.3%. The combination of an L/G ratio of 0.006 and solvent with a composition of 5%-mass NaOH, 15%-mass NaHCO3, and 18.9%-mass Na2CO3 produced the highest H2S selectivity of 23.1 (379.7% H2S selectivity increase).

Single-Stranded DNA Recognition over Fluorescent Gold-Aryl Nanoparticles

Fluorescence labeling of gold-aryl nanoparticles, AuNPs-COOH, was achieved by the covalent derivatization with dansyl chloride (DNS-Cl) reagent (5-naphthalene-1-sulfonyl chloride) for potential ssDNA recognition. The fluorescent gold nanoparticles of AuNPs-C6H4-4-COO-dansyl (AuNPs-DNS) of spherical shape and a size of 19.3 ± 8.3 nm were synthesized in a carbonate-bicarbonate buffer (pH = 10.6) at 37 °C. The fluorescence emission at 475 nm was acquired using fluorescence spectroscopy and investigated using time-resolved photoluminescence. The conjugation of ssDNA to AuNPs-DNS using the freeze-thaw and salt-aging methods was confirmed by fluorescence emission quenching, gel electrophoresis separation, and lifetime decrease. Conjugated ssDNA to AuNPs-DNS using the freeze-thaw method was more efficient than the salt-aging method. The purity of ssDNA upon conjugation was measured with optical density, and the obtained A260/A280 ratio was in the range of 1.7–2.0. This research can be applied to other nucleotide recognition and theranostics.

Aqueous-Mediated Synthesis and Characterization of Gelatin Methacryloyl for Biomedical Applications

In recent years, gelatin methacryloy¬l (GelMA)-based hydrogels have been widely used in many biomedical applications, particularly tissue engineering, due to their biocompatibility and tunable physicochemical, mechanical, and other functional properties. Phosphate buffer saline (PBS) or carbonate-bicarbonate buffer are frequently used to make GelMA. In this article, the authors provide an elegant aqueous-mediated synthesis and characterization of GelMA. The experimental conditions were optimized and extensively discussed. The results of proton nuclear magnetic resonance (1H NMR) and Fourier transform infrared spectroscopy (FTIR) confirmed the formation of GelMA with characteristic absorption peaks and chemical functional groups. The morphological analysis done with scanning electron microscopy (SEM) showed the porous nature of the GelMA with an average pore size of 80 microns. It was also found that the gelation properties of aqueous-mediated GelMA hydrogel were highly tunable by varying the percentage of gel concentration, which yields a wide range of tunable physicochemical properties. The preparation of this kind of aqueous-mediated GelMA is cost-effective compared to their counterparts and easy to prepare in laboratory settings with high yield under optimal conditions.

Alkaliphilic bacteria retrieved from uranium mining effluent: Characterization, U sequestration and remediation potential

Bacteria with the potential to sequester uranium (U) from carbonate-containing alkaline wastewaters were investigated. The two bacteria designated as MPW02 and MPW03 were isolated from uranium mine wastewaters and characterized by molecular methods as belonging to the genera Aeromonas and Bacillus, respectively. Uranium sequestration studies were performed at different carbonate–bicarbonate buffer concentrations and indicated the negative impact on the sequestering property of the two isolates. The observed maximum loading capacity by the two isolates under alkaline conditions was 112 and 36 mg U per gram of dry biomass, respectively. Heat inactivated MPW03 biomass retained the U sequestration capacity as that of living cells, whereas MPW02 dead biomass had a reduced U loading capacity. Kinetic models were applied to the experimental data to determine the mechanism of sequestration and found that two isolates followed a pseudo-second-order kinetic equation. Similarly, the experimental data were also modelled with Langmuir and Freundlich isotherms. The role of amino, hydroxyl and phosphate groups in U sequestration was elucidated by Fourier transform infrared (FTIR) spectroscopy. Further, the study shows that the two isolates adopted distinct mechanisms (chemisorption versus active metabolism dependent process) for U sequestration. Overall, this study signifies the potential application of these two bacteria for treating alkaline wastewaters containing U.

Uranium sequestration abilities of Bacillus bacterium isolated from an alkaline mining region

The present study elaborates uranium sequestration by bacteria from alkaline wastewaters. In the investigation, a few bacterial strains were isolated from alkaline uranium mine water and were tested for uranium sequestration properties 16S rRNA analysis assigned the 10 bacterial isolates to 4 genera of Actinobacteria and Firmicutes. Among all the isolates tested, the strain Bacillus aryabhattai (TP03) has shown superior sequestration capacity at 5 and 10 mg/L U in 1 mM carbonate-bicarbonate buffer at pH 9.2. At low uranium concentrations (5 mg/L as uranyl carbonate), the strain could sequester ~70% of the uranium in 6 h with a loading capacity of 4.3 mg U/g dry bacterial biomass. Increase in carbonate-bicarbonate buffer concentrations and pH reduced the sequestration capacity. Scanning electron microscopy and energy dispersive X-ray fluorescence spectroscopy studies indicated the presence of uranium with the bacterial biomass. Fourier transform infra-red spectroscopy results confirmed the uranium sequestration by cell membrane phosphate, amide, and carboxyl functional groups. Transmission electron microscopy study showed uranium presence within the cell cytoplasm, thus supporting the hypothesis on active metabolism-dependent bioaccumulation of uranium. The kinetics study of uranium sequestration was well fitted to the pseudo-second-order model. Overall, this study infers that the isolated alkaliphilic bacteria from the mine waters have significant sequestration property for treating uranium-containing alkaline wastewaters.

Effect of alkaline pH and nitrogen starvation on the triacylglycerol (TAG) content, growth, biochemical composition, and fatty acid profile of Auxenochlorella protothecoides KP7

Microalgae can accumulate substantial amounts of triacylglycerol, the primary feedstock for biodiesel production, under different stress conditions. In this study, exposure to alkaline pH (pH 10) using carbonate-bicarbonate buffer, nitrogen starvation, and both were applied to induce triacylglycerol accumulation in Auxenochlorella protothecoides KP7. In addition to triacylglycerol accumulation, growth, biochemical composition, and fatty acid profiles were examined in detail and compared. Our results illustrated that the combination of nitrogen starvation and alkaline pH led to significant increases in triacylglycerol and starch contents and drastic decreases in chlorophyll and protein contents compared with their control levels. Triacylglycerol levels, the triacylglycerol/total lipid ratio, and lipid productivities were significantly increased after 7 days of cultivation under the combined stress compared with the effects of nitrogen starvation alone. After prolonged cultivation under the combined stress, triacylglycerol content reached up to 25.01% of the dry cell weight and constituted up to 81.25% of total lipids. Under the combined stress, the major fatty acids in the total lipid of A. protothecoides KP7 were C18:1 (57.5%), C18:2 (19.5%), C16:0 (12.5%), and C18:3 (5.6%), and the percentages of saturated fatty acids, monounsaturated fatty acids, and polyunsaturated fatty acids represented 16.3, 58.4, and 25.1% of the total fatty acids, respectively. Furthermore, the combined stress was associated with the lowest iodine value (97.64 g I2 (100 g)−1), highest oxidative stability (7.29 h), and highest cetane number (55.26) among the examined conditions. The use of nitrogen-free medium containing carbonate-bicarbonate buffer for cultivation appears promising for enhancing triacylglycerol production in A. protothecoides.

A three-dimensional origami microfluidic device for paper chromatography: Application to quantification of Tartrazine and Indigo carmine in food samples

Herein, we report three-dimensional paper chromatography (3D-PC) as a micro-chromatographic platform. The method was based on applying the origami microfluidic device for separation, coupled by colorimetric methods for simultaneous determination. The microfluidic device fabrication was a facile printing approach. Two azo food dyes, Tartrazine (E102) and Indigo carmine (E132), were selected as a model analyte, while carbonate-bicarbonate buffer was used as the mobile phase. Our micro-chromatographic device is associated with two big advantages including needing very small volume of mobile phase ( ~12 µL) and ultrafast separation time (~35 s). Under the optimal conditions, the method provided acceptable linear ranges of 0. 0 g L1–18.0 g L1 (R2 = 0.997) for E102 and 0.070 g L1–10.0 g L1 for E132 and the limits of detection (3σ/slope) were evaluated as 0.620 and 0.060 g L1, respectively. The proposed method was successfully applied in the separation and quantification of these dyes in commercial food products such as jelly, candy, and four kinds of drink samples without any sample preparation prior to analysis. The mean recovery values for the real sample analysis were in the range of 100.14%–102.38% for E132 and E102 respectively. The inter-device relative standard deviations were in the ranges of 1.5%–11.8%. In total, our chromatographic μPAD is small (1.0 cm × 1.0 cm × 0.5 cm), portable, inexpensive, no need of specialized user, requires low volumes of sample (0.5 μL), and can perform separation using 12 μL of aqueous mobile phase in very short time.

Human BCR analysis of single-sorted, putative IgE+ memory B cells in food allergy

R. Jimenez-Saiz, Y. Ellenbogen and K. Bruton et al. developed a method to identify bona fide IgE+ MBCs in humans, demonstrated their extreme rarity in circulation and cautioned against the clinical utility of their assessment.

Development of Dot-ELISA Technique for Estimation of Milk Progesterone and Pregnancy Diagnosis using PVDF Membrane

An analytical hormone separation method and dot enzyme linked immunosorbant assay (dot-ELISA) for quantitation of hormone are described. For extraction of progesterone from milk chloroform methanol mixture was used. For Dot ELISA, conjugate was prepared by immunoglobulin isolated from whole serum by ammonium sulphate precipitation method and conjugated with Horse radish Peroxidase by modified gluteraldehyde procedure. For immobilization of progesterone to PVDF membrane a number of solvents were tried viz., Methanol, Methanol + Carbonate-bicarbonate buffer, Methanol + PBS, Ethanol and 70 per cent isopropanol. On observation following Dot ELISA procedure, 70 per cent isopropanol was selected as best. Dot ELISA of serially diluted progesterone was performed to get the best titre of conjugate selected for further studies. For standard colour of dot with different progesterone concentration, Dot ELISA with varying concentration of progesterone was performed. The new technique was thus developed for estimation of progesterone using PVDF membrane and 70 per cent isopropanol as solvent. The developed Dot ELISA was also used for estimation of progesterone and pregnancy diagnosis from cattle milk sample and technique was validated. This techniques may be useful for estimation of other steroid hormones.

Effects of vehicle microdialysis solutions on cutaneous vascular responses to local heating.

Microdialysis is a minimally invasive technique often paired with laser Doppler flowmetry to examine cutaneous microvascular function, yet presents with several challenges, including incompatibility with perfusion of highly lipophilic compounds. The present study addresses this methodological concern, with an emphasis on the independent effects of commonly used vehicle dialysis solutions to improve solubility of pharmacological agents with otherwise low aqueous solubility. Four microdialysis fibers were placed in the ventral forearm of eight subjects (4 men, 4 women; 25 ± 1 yr) with sites randomized to serve as 1) control (lactated Ringer's), 2) Sodium carbonate-bicarbonate buffer administered at physiological pH [SCB-HCl; pH 7.4, achieved via addition of hydrochloric acid (HCl)], 3) 0.02% ethanol, and 4) 2% dimethyl sulfoxide (DMSO). After baseline (34°C), vehicle solutions were administered throughout a standardized local heating protocol to 42°C. Laser Doppler flowmetry provided an index of blood flow. Cutaneous vascular conductance was calculated and normalized to maximum (%CVCmax, sodium nitroprusside and 43°C local heat). The SCB-HCl solution increased baseline %CVCmax (control: 9.7 ± 0.8; SCB-HCl: 21.5 ± 3.5%CVCmax; P = 0.03), but no effects were observed during heating or maximal vasodilation. There were no differences with perfusion of ethanol or DMSO at any stage of the protocol ( P > 0.05). These data demonstrate the potential confounding effects of some vehicle dialysis solutions on cutaneous vascular function. Notably, this study provides evidence that 2% DMSO and 0.02% ethanol are acceptable vehicles with no confounding local vascular effects to a standardized local heating protocol at the concentrations presented. NEW & NOTEWORTHY This study examined the independent effects of common vehicle solutions on cutaneous vascular responses. A basic buffer (SCB-HCl) caused baseline vasodilation; 2% DMSO and 0.02% ethanol had no effects. This highlights the need for considering potential confounding effects of solubilizing solutions when combined with low aqueous soluble pharmacological agents. Importantly, DMSO and ethanol do not appear to influence cutaneous vascular function during baseline or local heating at the concentrations studied, allowing their use without confounding effects.

Development and validation of a house finch interleukin-1\u03b2 (HfIL-1\u03b2) ELISA system

BackgroundA unique clade of the bacterium Mycoplasma gallisepticum (MG), which causes chronic respiratory disease in poultry, has resulted in annual epidemics of conjunctivitis in North American house finches since the 1990s. Currently, few immunological tools have been validated for this songbird species. Interleukin-1β (IL-1β) is a prototypic multifunctional cytokine and can affect almost every cell type during Mycoplasma infection. The overall goal of this study was to develop and validate a direct ELISA assay for house finch IL-1β (HfIL-1β) using a cross-reactive chicken antibody.MethodsA direct ELISA approach was used to develop this system using two different coating methods, carbonate and dehydration. In both methods, antigens (recombinant HfIL-1b or house finch plasma) were serially diluted in carbonate-bicarbonate coating buffer and either incubated at 4 °C overnight or at 60 °C on a heating block for 2 hr. To generate the standard curve, rHfIL-1b protein was serially diluted at 0, 3, 6, 9, 12, 15, 18, 21, and 24 ng/mL. Following blocking and washing, anti-chicken IL-1b polyclonal antibody was added, plates were later incubated with detecting antibodies, and reactions developed with tetramethylbenzidine solution.ResultsA commercially available anti-chicken IL-1β (ChIL-1β) polyclonal antibody (pAb) cross-reacted with house finch plasma IL-1β as well as bacterially expressed recombinant house finch IL-1β (rHfIL-1β) in immunoblotting assays. In a direct ELISA system, rHfIL-1β could not be detected by an anti-ChIL-1β pAb when the antigen was coated with carbonate-bicarbonate buffer at 4°C overnight. However, rHfIL-1β was detected by the anti-ChIL-1β pAb when the antigen was coated using a dehydration method by heat (60°C). Using the developed direct ELISA for HfIL-1β with commercial anti-ChIL-1β pAb, we were able to measure plasma IL-1β levels from house finches.ConclusionsBased on high amino acid sequence homology, we hypothesized and demonstrated cross-reactivity of anti-ChIL-1β pAb and HfIL-1β. Then, we developed and validated a direct ELISA system for HfIL-1β using a commercial anti-ChIL-1β pAb by measuring plasma HfIL-1β in house finches.

Evaluation of Dried Urine Spot Method to Screen Cotinine among Tobacco Dependents: An Exploratory Study.

Background and Objectives:Assessment of cotinine, a metabolite of nicotine in body fluids, is an important approach for validating the self-report among tobacco users. Adaptation of assays on dried urine spots (DUSs) has advantages of ease of collection, transportation, minimal invasiveness, and requirement of small volume. The aim of the present study was to develop an efficient method for testing cotinine in DUSs and evaluating its clinical applicability.Methods:This involved optimization of conditions for detection, recovery, and stability of cotinine from dried urine, spotted on filter paper. Enzyme-linked immunosorbent assay was used for screening, whereas confirmation was done by gas chromatography. For clinical applicability, urine samples of tobacco users were tested.Results and Interpretation:Water was found to be a suitable extracting solvent as compared to carbonate-bicarbonate buffer (pH 9.2) and saline. Screening was achieved by two punches taken from a 20 μl (diameter 1.3 cm) spotted urine samples, and confirmation was achieved by five complete circles each of 20 μl sample volume. The recovery was found to be 97% in water. Limit of detection for the method was found to be 100 ng/ml. No signs of significant degradation were found under all storage conditions. All the urine samples of tobacco users were found to be positive by a conventional method as well as DUSs, and the method proved to be efficient.Conclusions:DUS samples are a useful alternative for biological monitoring of recent nicotine use, especially in developing countries where sample logistics could be an important concern.

Precise Tuning of Facile One-Pot Gelatin Methacryloyl (GelMA) Synthesis.

Gelatin-methacryloyl (GelMA) is one of the most commonly used photopolymerizable biomaterials in bio-applications. However, GelMA synthesis remains suboptimal, as its reaction parameters have not been fully investigated. The goal of this study is to establish an optimal route for effective and controllable GelMA synthesis by systematically examining reaction parameters including carbonate-bicarbonate (CB) buffer molarity, initial pH adjustment, MAA concentration, gelatin concentration, reaction temperature, and reaction time. We employed several analytical techniques in order to determine the degree of substitution (DS) and conducted detailed structural analysis of the synthesized polymer. The results enabled us to optimize GelMA synthesis, showing the optimal conditions to balance the deprotonation of amino groups with minimizing MAA hydrolysis, which led to nearly complete substitution. The optimized conditions (low feed ratio of MAA to gelatin (0.1 mL/g), 0.25 M CB buffer at pH 9, and a gelatin concentration of 10–20%) enable a simplified reaction scheme that produces GelMA with high substitution with just one-step addition of MAA in one pot. Looking forward, these optimal conditions not only enable facile one-pot GelMA synthesis but can also guide researchers to explore the efficient, high methacrylation of other biomacromolecules.

Production of Single Cell Protein from Sugarcane Bagasse by Saccharomyces cerevisiae in Tray Bioreactor

In this study, solid state fermentation (SSF) was carried out to produce single cell protein (SCP) from sugarcane bagasse using Saccharomyces cerevisiae. The SSF experiment were performed in a tray bioreactor. The influence of several parameters including extraction buffer, initial moisture content of substrate, fermentation time, relative humidity in bioreactor, the bioreactor temperature and pretreatment of substrate on SCP production yield was considered. Among the used extraction buffers, carbonate-bicarbonate buffer was the most effective one for protein extraction. The obtained results revealed that the suitable fermentation conditions were initial substrate moisture content of 70%, fermentation time of 72 h, relative humidity of 85%, bioreactor temperature of 35 oC and pretreatment of substrate using 2% NaOH solution; at this optimum condition protein production yield of 13.41% was attained. The amino acid analysis of the produced protein showed that the product contained almost all of the essential amino acid as well as some non-essential amino acids.

Determination of Concentration of Amphiphilic Polymer Molecules on the Surface of Encapsulated Semiconductor Nanocrystals.

We present a method for the determination of the average number of polymer molecules on the surface of A(II)B(VI) luminescent core-shell nanocrystals (CdSe/ZnS, ZnSe/ZnS quantum dots, and CdS/ZnS nanorods) encapsulated with amphiphilic polymer. Poly(maleic anhydride-alt-1-tetradecene) (PMAT) was quantitatively labeled with amino-derivative of fluorescein and the average amount of PMAT molecules per single nanocrystal was determined using optical absorption of the dye in the visible spectral range. The average amount of PMAT molecules grows linearly with the surface area of all studied nanocrystals. However, the surface density of the monomer units increases nonlinearly with the surface area, because of the increased competition between PMAT molecules for Zn-hexanethiol surface binding sites. The average value of zeta potential (ζ = -35 mV) was found to be independent of the size, shape, and chemical composition of nanocrystals at fixed buffer parameters (carbonate-bicarbonate buffer, pH 9.5 and 5 mM ionic strength). This finding is expected to be useful for the determination of the surface density of remaining carboxyl groups in PMAT-encapsulated nanocrystals.

Gas absorption and reaction in a wet pneumatic foam

Results for the rate of absorption of carbon dioxide gas into a pneumatic (i.e. continuously rising) foam formed from a sodium carbonate–bicarbonate buffer solution stabilised by a polyglycol frother are presented. Previous studies upon the use of gas–liquid foam for gas absorption operations have demonstrated limited potential for the technique, mainly because the liquid films rapidly become saturated with the absorbing gas due to the relatively low liquid fraction within the foam. However, by adding washwater to the free surface of the foam we created a wetter and more stable foam that (1) exhibits a high liquid fraction and therefore avoids film saturation, and (2) creates greater liquid advection past the gas-liquid surfaces, thereby enhancing the mass transfer coefficient. The interfacial area achieved within the foam was in the range 2100–3200m2m−3 (i.e. much higher than in conventional gas-liquid contactors and the liquid-side mass transfer coefficient was the same magnitude as that achieved in packed beds (i.e. 4–8×10–5ms−1). Indeed, by modelling the foam as a packed-bed of solid spheres (with no adjustable constants), the mass-transfer coefficient in a bed of closely packed solid spheres was found to be in satisfactory agreement with the mass-transfer measured in the wet gas-liquid foam. The hydrodynamic state and the slip velocity between gas and liquid phases is required for the design of wet foam absorption columns, and this can be estimated using a theory of pneumatic foam (Stevenson, 2007).

SOLUBILITY OF AMMONIUM ACID URATE NEPHROLITHS FROM BOTTLENOSE DOLPHINS (TURSIOPS TRUNCATUS)

Nephrolithiasis has been identified in managed populations of bottlenose dolphins (Tursiops truncatus); most of these nephroliths are composed of 100% ammonium acid urate (AAU). Several therapies are being investigated to treat and prevent nephrolithiasis in dolphins including the alkalization of urine for dissolution of nephroliths. This study evaluates the solubility of AAU nephroliths in a phosphate buffer, pH range 6.0-8.0, and in a carbonate-bicarbonate buffer, pH range 9.0-10.8. AAU nephroliths were obtained from six dolphins and solubility studies were conducted using reverse-phase high performance liquid chromatography with ultraviolet detection at 290 nm. AAU nephroliths were much more soluble in a carbonate-bicarbonate buffer, pH range 9.0-10.8 compared to phosphate buffer pH range 6.0-8.0. In the pH range 6.0-8.0, the solubility was 45% lower in potassium phosphate buffer compared to sodium phosphate buffer. When citrate was used along with phosphate in the same pH range, the solubility was improved by 13%. At pH 7 and pH 8, 150 mM ionic strength buffer was optimum for dissolution. In summary, adjustment of urinary pH alone does not appear to be a useful way to treat AAU stones in bottlenose dolphins. Better understanding of the pathophysiology of AAU nephrolithiasis in dolphins is needed to optimize kidney stone prevention and treatment.