HA Concentration Research Articles

Four-photon-excited fluorescence resonance energy transfer in an aqueous system from ZnSe:Mn/ZnS quantum dots to hypocrellin A.

In this work, we established a fluorescence resonance energy transfer (FRET) system between ZnSe:Mn/ZnS quantum dots and Hypocrellin A (HA, a photosensitizer used for photodynamic therapy of cancer) in aqueous solution, excited by four-photon. Here, the QDs are the donors and the HA are the acceptors. The four-photon-excited fluorescence resonance energy transfer spectrum was obtained under 1300nm femtosecond laser pluses. The experimental results indicated that the highest efficiency of FRET can reach up to 61.3%. Furthermore, the viability test in cancer cells was further demonstrated for biological applications of FRET system. When FRET occurs the cell killing rate of the cancer cells will reach to 84.8% with the 1mM concentration of HA. Our work demonstrates that while the four-photon excited FRET system is promising in both optics and biological applications, is also needs further investigation.

Research on the preparation, biocompatibility and bioactivity of magnesium matrix hydroxyapatite composite material

In this paper, magnesium matrix hydroxyapatite composite material was prepared by electrophoretic deposition method. The optimal process parameters of electrophoretic deposition were HA suspension concentration of 0.02 kg/L, aging time of 10 days and voltage of 60V. Animal experiment and SBF immersion experiment were used to test the biocompatibility and bioactivity of this material respectively. The SD rats were divided into control group and implant group. The implant surrounding tissue was taken to do tissue biopsy, HE dyed and organizational analysis after a certain amount of time in the SD rat body. The biological composite material was soaked in SBF solution under homeothermic condition. After 40 days, the bioactivity of the biological composite material was evaluated by testing the growth ability of apatite on composite material. The experiment results showed that magnesium matrix hydroxyapatite biological composite material was successfully prepared by electrophoretic deposition method. Tissue hyperplasia, connective tissue and new blood vessels appeared in the implant surrounding soft tissue. No infiltration of inflammatory cells of lymphocytes and megakaryocytes around the implant was found. After soaked in SBF solution, a layer bone-like apatite was found on the surface of magnesium matrix hydroxyapatite biological composite material. The magnesium matrix hydroxyapatite biological composite material could promot calcium deposition and induce bone-like apatite formation with no cytotoxicity and good biocompatibility and bioactivity.

Modeling the effects of surfactant, hardness, and natural organic matter on deposition and mobility of silver nanoparticles in saturated porous media

This study aims to provide insights into the mechanisms governing the deposition and retention of silver nanoparticles (AgNPs) in saturated porous media. Column experiments were conducted with quartz sand under saturated conditions to investigate the deposition kinetics of AgNPs, their mobility at different groundwater hardnesses (10–400 mg/L as CaCO3), and humic acid (HA, 0–50 mg/L as dissolved organic carbon [DOC]). An anionic surfactant, sodium dodecyl sulfate (SDS), was used as a dispersing agent to prepare a SDS-AgNPs suspension. The deposition kinetics of AgNPs were highly sensitive to the surfactant concentration, ionic strength, and cation type in solution. The breakthrough curves (BTCs) of SDS-AgNPs suggested that the transport and retention were influenced by groundwater hardness and HA. At low water hardness and high HA, high mobility of SDS-AgNPs was observed in saturated conditions. However, the retention of SDS-AgNPs increased substantially in very hard water with a low concentration of HA, because of a decreased primary energy barrier and the straining effect during the course of transport experiments. A modified clean-bed filtration theory and a two-site kinetic attachment model showed good fits with the BTCs of SDS-AgNPs. The fitted model parameters (katt and kstr) could be used successfully to describe that the retention behaviors were dominated by electrostatic and electrosteric repulsion, based on extended Derjaguin-Landau-Vaerwey-Overbeek calculations.

Indirect fabrication of hydroxyapatite/β-tricalcium phosphate scaffold for osseous tissue formation using additive manufacturing technology

Patient specific HA/β-TCP scaffold were fabricated using an indirect fabrication approach which involves the application of rapid prototyping technology. β-TCP powder with 10, 20 and 30 % HA concentrations were analyzed for different sintering temperatures. Scaffolds were evaluated by Scanning Electron Microscopy, X-ray diffraction, compression tests, Fourier transform infrared spectroscopy and cytotoxicity tests using human osteosarcoma cell line. Results include HA/β-TCP scaffold porosity, volumetric shrinkage, mechanical properties, bonding, structural phase change and cytotoxicity.

Humic Acid Removal by Combining the Magnetic Property of Maghemite with the Adsorption Property of Nanosized Hydroxyapatite

Maghemite incorporated hydroxyapatite (HAP) nanocomposite was prepared by in situ precipitation of the calcium phosphate phase in an iron oxide colloidal suspension. The resultant nanocomposite was characterized by x-ray diffraction, Fourier transform infrared spectrometer, transmission electron microscope, N2 adsorption analysis, and vibrating sample magnetometry. The potential of HAP/γ-Fe2O3 nanocomposite for HA adsorption from aqueous solution was evaluated by batch experiments and adsorption kinetic tests. HA adsorption amount on the adsorbent decreased with increasing solution pH and the presence of KNO3 and alkali-earth metal ions resulted in enhanced HA adsorption. HA adsorption onto HAP/γ-Fe2O3 nanocomposite could be well described by Freundlich and Sips models, while HA adsorption process on the adsorbent obeyed pseudo-second-order kinetics and the adsorption rates decreased with increasing initial HA concentration. This study showed that the HAP/γ-Fe2O3 nanocomposite could be used as an efficient and magnetically separable adsorbent for the removal of HA from aqueous solution. Subsequent studies demonstrated that the HA-loaded HAP/γ-Fe2O3 nanocomposite could be further applied for the highly efficient adsorption of methylene blue (MB) and separated from the medium by a simple magnetic process.

Cochlear perfusion with a viscous fluid

The flow of viscous fluid in the cochlea induces shear forces, which could provide benefit in clinical practice, for example to guide cochlear implant insertion or produce static pressure to the cochlear partition or wall. From a research standpoint, studying the effects of a viscous fluid in the cochlea provides data for better understanding cochlear fluid mechanics. However, cochlear perfusion with a viscous fluid may damage the cochlea. In this work we studied the physiological and anatomical effects of perfusing the cochlea with a viscous fluid. Gerbil cochleae were perfused at a rate of 2.4 μL/min with artificial perilymph (AP) and sodium hyaluronate (Healon, HA) in four different concentrations (0.0625%, 0.125%, 0.25%, 0.5%). The different HA concentrations were applied either sequentially in the same cochlea or individually in different cochleae. The perfusion fluid entered from the round window and was withdrawn from basal scala vestibuli, in order to perfuse the entire perilymphatic space. Compound action potentials (CAP) were measured after each perfusion. After perfusion with increasing concentrations of HA in the order of increasing viscosity, the CAP thresholds generally increased. The threshold elevation after AP and 0.0625% HA perfusion was small or almost zero, and the 0.125% HA was a borderline case, while the higher concentrations significantly elevated CAP thresholds. Histology of the cochleae perfused with the 0.0625% HA showed an intact Reissner's membrane (RM), while in cochleae perfused with 0.125% and 0.25% HA RM was torn. Thus, the CAP threshold elevation was likely due to the broken RM, likely caused by the shear stress produced by the flow of the viscous fluid. Our results and analysis indicate that the cochlea can sustain, without a significant CAP threshold shift, up to a 1.5 Pa shear stress. Beside these finding, in the 0.125% and 0.25% HA perfusion cases, a temporary CAP threshold shift was observed, perhaps due to the presence and then clearance of viscous fluid within the cochlea, or to a temporary position shift of the Organ of Corti. After 0.5% HA perfusion, a short latency positive peak (P0) appeared in the CAP waveform. This P0 might be due to a change in the cochlea's traveling-wave pattern, or distortion in the cochlear microphonic.

Properties of calcium phosphates ceramic composites derived from natural materials

In this study, ceramics containing mixed phases of hydroxyapatite/beta-tricalcium phosphate (HA/β-TCP) were fabricated by a solid-state reaction technique. The HA powder was synthesized from cockle shells while the β-TCP powder was synthesized from egg shells. Pure HA and β-TCP fine powders were successfully obtained. The HA and β-TCP were mixed and subjected to a thermal treatment up to 1100°C. To form the mixed phase ceramics, the resulting powders were sintered at 1350°C. Effects of HA concentration on the properties of the studied ceramic were investigated. X-ray diffraction analysis revealed that all samples presented multiphase of calcium phosphate compounds. Average grain size of the ceramics decreased with the HA additive content. The 75wt% HA ceramic showed the maximum hardness value (5.5GPa) which is high when compared with many calcium phosphate ceramics. In vitro bioactivity test indicated that apatite forming increased with the HA additive content. To increase antibacterial activity, selected ceramics were coated with AgNO3. Antibacterial test suggested that an Ag compound coating on the ceramics could improve the antibacterial ability of the studied ceramics. In addition, the antibacterial ability for the Ag coated ceramics depended on the porosity of the ceramics.

Mineralization at Titanium Surfaces is a Two-Step Process.

Mapping the initial reaction of implants with blood or cell culture medium is important for the understanding of the healing process in bone. In the present study, the formation of low crystalline carbonated hydroxyapatite (CHA) onto commercially pure titanium (Ti) implants from cell culture medium and blood, is described as an early event in bone healing at implants. The Ti-implants were incubated with cell culture medium (DMEM) or whole blood and the surface concentration of Ca, P and HA was analyzed by XPS, EDX and Tof-SIMS. After incubation with DMEM for 16 h and 72 h, EDX and XPS analysis showed stable levels of Ca and P on the Ti-surface. ESEM images showed an even distribution of Ca and P. Further analysis of the XPS results indicated that CHA was formed at the implants. Analysis with ToF-SIMS yielded high m.w. fragments of HA, such as Ca2PO4 at m/z 174.9 and Ca3PO5 at m/z 230.8, as secondary ions at the Ti-surfaces. Analysis of implants incubated in blood for 16 h, with ToF-SIMS, showed initial formation of CHA yielding CaOH as secondary ion. The results indicate that early mineralization at Ti-surfaces is an important step in the healing of implants into bone.

Fabrication and mechanical properties of hydroxyapatite filled polyetheretherketone functional gradient biomaterials

Hydroxyapatite filled polyetheretherketone functional gradient biomaterials (HA/PEEK FGBm) were fabricated through layer-stacking method and in combination with hot press moulding technology. The influences of total HA content, HA concentration difference between adjacent layers (HCDBAL) and annealing treatment on the tensile properties of HA/PEEK FGBm were investigated. The results indicated that the tensile strength and tensile fracture strain of HA/PEEK FGBm decreased with the increasing total HA content. Contrarily, the tensile modulus of HA/PEEK FGBm increases with the rise of total HA content. The tensile strength and modulus of the HA/PEEK FGBm first increased and then decreased with the rise of HCDBAL. Such change in behaviour was more obvious for the HA/PEEK FGBm with 30% total HA content. Furthermore, the tensile strength and modulus of the HA/PEEK FGBm were obviously improved after annealing treatment.

Simultaneous removal of humic acid/fulvic acid and lead from landfill leachate using magnetic graphene oxide

The elimination of organic matters and heavy metals in landfill leachate remains a longstanding challenge in wastewater treatment. In this study, magnetic graphene oxide (MGO) was synthesized and investigated to explore the possibility of applying in the simultaneous removal of HA/FA and Pb(II) from landfill leachate. MGO was characterized by Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscope. In single system, the sorption isotherm for FA on MGO at 25°C were better described by Freundlich model than Langmuir and Temkin models with a maximum adsorption capacity of 72.38mg/g. The isotherm data for HA at 25°C was fitted well both Freundlich and Temkin models with a maximum adsorption capacity of 98.82mg/g, while the isotherm data for Pb(II) at 25°C was fitted well both Langmuir and Temkin models with a maximum adsorption capacity of 58.43mg/g. In binary system, results showed that TOC removal (both in HA and FA) enhanced with increasing Pb(II). Furthermore, TOC removal enhancement caused by the increase of Pb(II) in HA-Pb(II) system was greater than that in FA-Pb(II), which was caused by HA possessing more substantial aromatic rings than FA. Noticeably, Pb(II) removal steeply increased to the maximum (about 87%) with increasing concentration of HA, when HA concentration was less than 110mg/L, and considerably decreased with increasing concentration of HA, when HA concentration was greater than 110mg/L. However, Pb(II) removal slightly increased and remained a considerable percentage with a little fluctuation as the FA concentration increased. The regenerated MGO still had high efficiency both for HA/FA and for Pb(II) in the third cycle. The removal efficiencies of Pb(II), HA/FA in real water and in landfill leachate were almost analogues to that in ultrapure water. The successful application of MGO for removing HA/FA and Pb(II) in tap water and landfill leachate provided a possibility of MGO used for real wastewaters treatment.

Synergistic Removal of Humic Acid in Water by Coupling Adsorption and Photocatalytic Degradation Using TiO2/Coconut Shell Powder Composite

The feasibility of applying nanoscale TiO2/coconut shell powder (TCNSP) composite to remove HA in aqueous solution was evaluated, and the optimization of the photocatalytic systems using newly developed TCNSP composite was performed. The developed TCNSP composite has high specific surface area (i.e., 454 m2/g) and great porosity (i.e., 66.9%) with pore size of less than 5 μm. High removal efficiencies (≥95%) of HA were observed due to the significant synergistic effects by coupling adsorption and photocatalytic reaction of TCNSP composite. As the initial concentration of HA increased, the degradation rate (Kapp) decreased due to HA sorption saturation to the surface of TCNSP composite and the photon interception by HA molecules in aqueous solution. Since the increased loading amount of TCNSP composite enhanced the number of active sites,Kappvalues increased until the optimum loading amount of TCNSP composite. As pH values increased, HA removal efficiency decreased due to increasing electrostatic repulsion between HA and TCNSP composite. Based on the response surface methodology, higher HA removal efficiencies were obtained with acidic condition, longer reaction time, and appropriated loading amount of TCNSP. Further pilot-scale study is in progress using TCNSP composite combined with UVC to remove HA from large amounts of surface water (i.e., 200 m3/d).

МАСС-СПЕКТРОМЕТРИЯ СУПРАМОЛЕКУЛЯРНЫХ КОМПЛЕКСОВ ГЛИЦИРРИЗИНОВОЙ КИСЛОТЫ И СТРЕПТОМИЦИНА

Глицирризиновая кислота (ГК), выделенная из корней солодки голой Glycyrrhiza glabra L. и Gl. uralensis F., обладает уникальными комплексообразующими свойствами, которые широко используются в синтезе новых лекарственных форм на основе молекулярных комплексов с фармаконами. В таких гетерогенных комплексах молекулы ГК выступают в роли полидентантных лигандов, образующих с фармаконами супрамолекулярные комплексы различной стехиометрии. Целью данной работы является изучение комплексообразования растительных гликозидов с антимикробным препаратом стрептомицином для создания новых низкодозных фармсубстанций на основе глицирризиновой кислоты. В представленной работе впервые синтезированы и изучены методом УФ-спектроскопии и масс-спектрометрии с ионизацией электрораспылением гетерогенные супрамолекулярные комплексы ГК с антибиотиком стрептомицином (СТ), полученные при различных концентрациях «хозяина» и «гостя» в соотношении 1 : 1 и 4 : 1. Зарегистрированные изменения в спектре поглощения СТ в присутствии ГК с помощью УФ-спектроскопии доказывают формирование гетерогенных комплексов ГК-СТ в жидкой фазе. С использованием масс-спектрометрии зарегистрировано эффективное взаимодействие ГК и СТ с образованием различных гетерогенных супрамолекулярных структур с соотношением «хозяин: гость» 1 : 1, 2 : 1, 3 : 1, 3 : 2. При увеличении концентрации ГК наблюдали как увеличение степени самоассоциации ГК (до 4), так и образование комплекса с соотношением 4 : 1. Результаты исследований демонстрируют высокий потенциал использования глицирризиновой кислоты для синтеза новых форм антибактериального препарата стрептомицина в виде нековалентных молекулярных комплексов.

Syntesis of Glutardehide Crosslinked Superporous Chitosan with Polyphynil Alcohol Addition for Peat Water Humic Acid Absorption

<p><em>This research aims to synthezise the superporous adsorbent from chitosan using glutaraldehyde as a cross linker, NaHCO<sub>3</sub> as a porogen, and polyvinyl alcohol (PVA) as a reinforcing agent. Generally, the reaction of adsorbent synthesis was carried out through four steps: (1) the addition of PVA to the chitosan solution, (2) the addition of porogen, (3) the crosslinking of chitosan, and (4) the releasing of porogen. The obtained adsorbents were characterized by Fourier Transform Infra Red (FTIR) Spectroscopy, photograph of Digital Microscope (DM), and Scanning Electron Microscopy (SEM) to measure the porosity. The adsorbent was then be applied to adsorb of HA for adsorption capacity determination. The results showed that the addition of PVA and porogen during adsorbent synthesis has produced adsorbent with more compact and flexible physical properties and greater porosity. The adsorption test showed that the adsorption capacity of KPG is 33.07 mg/g. However, if the amount of used adsorbent is larger (based on the chitosan mass 1 g), the capacity adsorption of KPG is 141.74 mg/g. The initial concentration of HA contained in peat water was 45.64 mg/L, KPG can adsorb of HA as much as 95%.</em></p>

Determination of magnesium by the solution scanometric method in a coloured titan yellow magnesium hydroxide complex form

In this work, the magnesium content was determined by the solution scanometric method using titan yellow (TY) as a complexing agent in alkaline media. This method is based on scanning a solution containing the pink-coloured product of the combination of TY and the magnesium hydroxide complex. Hydroxylamine hydrochloride (HA) and starch were utilised as colour stabilizers and protective colloids, respectively. After the cells containing the sample solution were scanned, the colour of each cell was analysed with software written in Visual Basic (VB 6) in terms of the red, green and blue values. The parameters used for optimisation include the reaction time and the concentration of TY, sodium hydroxide, starch and HA. The system had a wide linear range between 0.070 and 30.000μgmL−1 concentrations of magnesium, with a detection limit of 0.058μgmL−1 and a relative standard deviation of 1.90% for the G colour value. In addition, the effects of some foreign species were investigated. The method was successfully applied for the determination of magnesium in almond gum and three water samples.

The roles of a pillared bentonite on enhancing Se(VI) removal by ZVI and the influence of co-existing solutes in groundwater

The zero-valent iron permeable reactive barrier (ZVI-PRB) is a promising technology for in-situ groundwater remediation. However, its long-term performance often declined due to the blocked reactive sites by corrosion products and by interference of co-existing solutes. In order to address these issues, a pillared bentonite (Al-bent) was homogeneously mixed with ZVI for removing selenate (Se(VI)) from simulated groundwater in column experiments. The Se(VI) removal was enhanced because first Al-bent could facilitate the mass transfer of Se(VI) from solution to iron surface and accelerate Se(VI) reduction. XANES analysis indicated that Se(VI) was almost completely reduced to Se(0) and Se(-II) of less toxicity and solubility by the ZVI/Al-bent mixture, and the buffering effect of Al-bent could maintain the pH at a lower level that favored the Se(VI) removal. Besides, Al-bent could transfer the corrosion products away from iron surface, leading to the enhanced reactivity and longevity of ZVI. The inhibition on reactivity towards Se(VI) in both the single ZVI and the ZVI/Al-bent systems increased in the order of Cl−<NO3−<HCO3−<SO42−, and the removal efficiency decreased with the increasing HA concentration. However, the lower decrease of Se(VI) removal in the ZVI/Al-bent system indicates its resistance to the interference of these co-existing solutes in groundwater.

Serum hyaluronic acid concentration predicts the progression of joint space narrowing in normal knees and established knee osteoarthritis - a five-year prospective cohort study.

IntroductionSerum hyaluronic acid (sHA) is a serum biomarker for knee osteoarthritis (OA). Although sHA concentration is elevated in patients with knee OA, the relationship between serum concentration and disease progression remains unclear. We examined the relationship between sHA concentration and radiographic progression of knee OA in a cohort of individuals followed for 5 years.MethodsWe prospectively enrolled 444 individuals and measured their sHA concentrations at baseline. Anterior-posterior weight bearing knee radiographs were obtained at baseline and the 5-year endpoint. Osteoarthritic knee changes were classified according to Kellgren–Lawrence (KL) grade, and joint space narrowing (JSN) was measured using a Knee Osteoarthritis Computer-Aided Diagnosis (KOACAD) system. Correlations between sHA concentration, progression in KL grade, and JSN were assessed using regression models, taking into account potentially confounding factors.ResultsOA progressed from KL grades 0 or 1 in 129 of the 323 knees, and from KL grades 2 or 3 in 61 of the 119 knees. Higher sHA concentrations were correlated with KL grade progression (p = 0.004). The mean JSN, as assessed by KOACAD over 5 years, was 0.23 ± 0.55 mm, and sHA concentration was positively correlated with progression of JSN in KL grades 0 or 1 (p = 0.021) and KL grades 2 or 3 (p = 0.008) knees.ConclusionSerum HA concentration was positively correlated with progression of KL grade. sHA was also positively correlated with progression of JSN in knees with and without OA, suggesting that sHA concentration may be a useful predictor of knee OA progression.

Comparative study of humic acid removal and floc characteristics by electrocoagulation and chemical coagulation.

The current study aims at investigating the efficiency of electrocoagulation for the removal of humic acid from contaminated waters. In parallel, conventional chemical coagulation was conducted to asses humic acid removal patterns. The effect of varying contributing parameters (matrix pH, humic acid concentration, type of electrode (aluminum vs. iron), current density, solution conductivity, and distance between electrodes) was considered to optimize the electrocoagulation process for the best attainable humic acid removal efficiencies. Optimum removals were recorded at pH of 5.0-5.5, an electrical conductivity of 3000 μS/cm at 25 °C, and an electrode distance of 1 cm for both electrode types. With aluminum electrodes, a current density of 0.05 mA/cm2 outperformed 0.1 mA/cm2 yet not higher densities, whereas a current density of 0.8 mA/cm2 was needed for iron electrodes to exhibit comparable performance. With both electrode types, higher initial humic acid concentrations were removed at a slower rate but ultimately attained almost complete removals. On the other hand, the best humic acid removals (∼90%) by chemical coagulation were achieved at 4 mg/L for both coagulants. Also, higher removals were attained at elevated initial humic acid concentrations. Humic acid removals of 90% or higher at an initial HA concentration of 40 mg/L were exhibited, yet alum performed better at the highest experimented concentration. It was evident that iron flocs were larger, denser, and more geometrical in shape compared to aluminum flocs.

Biodegradable composite scaffolds of poly(lactic‐co‐glycolic acid) 85:15 and nano‐hydroxyapatite with acidic microclimate controlling additive

The aim of this study was to prepare and characterize biodegradable scaffolds of poly(lactic‐co‐glycolic acid) (PLGA 85:15) and nano‐hydroxyapatite (HA) containing magnesium carbonate (MC) as acidic microclimate controlling additive. Porous and nonporous scaffolds of PLGA 85:15 and nano‐HA containing MC were prepared by solvent casting and particulate leaching method. Scaffolds were degraded at pH 7.4 phosphate buffer for 90 days. At regular intervals, pH of the degradation medium, release of degradation products, mass loss, water sorption, and tensile strength were measured. The results showed that the pH of the degradation medium significantly decreased with control specimens, whereas the scaffolds with MC did not show significant changes. In addition, acidic monomer release from the scaffolds with MC was found to be less, whereas the water sorption was found to be significantly higher. The tensile strength of the scaffold was found to be dependent on the concentration of HA and porosity. These results indicate that incorporation of MC to PLGA 85:15 scaffolds reduces the acidic microclimate with changes in mass loss, water sorption, and strength properties. POLYM. COMPOS., 38:1175–1182, 2017. © 2015 Society of Plastics Engineers

Effect of humic acid on survival, ionoregulation and hematology of the silver catfish, Rhamdia quelen (Siluriformes: Heptapteridae), exposed to different pHs

This study evaluates whether humic acid (HA; Aldrich) protects the silver catfish, Rhamdia quelen (Quoy & Gaimard, 1824), against exposure to acidic pH. Survival, levels of Na+, Cl- and K+ plasma, hematocrit, hemoglobin and erythrocyte morphometry were measured. Fish were exposed to 0, 10, 25 and 50 mg L 1 HA at four pH levels: 3.8, 4.0, 4.2 and 7.0 up to 96 hours. None of the fish exposed to pH 3.8 survived for 96 hours into the experiment, and survival of fish subjected to pH 4.0 decreased when HA concentration increased. Plasma Na+ levels decreased when pH was acidic, with no influence of HA, while Cl- levels declined at low pH with increased HA concentration. The levels of K+ at pH 4.0 and 4.2 increased without HA. Hematocrit and hemoglobin augmented under the effect of HA. At pH 4.0 and 4.2, erythrocytes of fish not exposed to HA were smaller, an effect that was partially offset by the presence of HA, since the values at pH 7.0 were higher. Although HA showed some positive effects changes in hematological and plasma K+a in silver catfish caused by exposure to acidic pH, the overall findings suggest that HA does not protect this species against acidic pH because it increased mortality and Cl- loss at pH 4.0.

Interactions of Eu(III) and 243Am(III) with humic acid-bound γ-Al2O3 studied using batch and kinetic dissociation techniques

The association of Eu(III) and 243Am(III) with humic acid-bound γ-Al2O3 (HA–Al2O3) was investigated using batch technique and the kinetic dissociation properties were studied using chelating resin. The results indicated that Eu(III) and 243Am(III) had very similar sorption properties. The kinetics of desorption of 243Am(III) from HA–Al2O3 hybrids were studied at three different pH values (pH 4.0, 5.0 and 6.0) after aging time for 2h, 4days, and 1month by adding chelating resin to remove the desorbed free 243Am(III) ions from the HA–Al2O3 hybrids. The fraction of 243Am(III) on the irreversible binding sites of the HA–Al2O3 hybrids increased as the pH increased. Two different 243Am(III)–HA–Al2O3 species (i.e., “fast” and “slow” dissociation kinetics, which represented the “weak” and “strong” species on reversible sites) were required to fit the kinetic dissociation results. Although 243Am(III) was initially a “fast” dissociating species, it became a “slow” dissociating species as the aging time increased and at low HA concentrations. When the HA concentration was high, the “fast” and “slow” dissociating species of 243Am(III) bound to HA–Al2O3 particles were not influenced by the aging time. These results describe the physicochemical behavior of trivalent lanthanides and actinides in the natural environment, which is important to understand the potential pollution of long-lived radionuclides.