pH Dissolution Research Articles

Exploring Co-Amorphous Formulations Of Nevirapine: Insights From Computational, Thermal, And Solubility Analyses.

This study aimed to assess the formation of nevirapine (NVP) co-amorphs systems (CAM) with different co-formers (lamivudine-3TC, citric acid-CAc, and urea) through combined screening techniques as computational and thermal studies, solubility studies; in addition to develop and characterize suitable NVP-CAM. NVP-CAM were obtained using the quench-cooling method, and characterized by differential scanning calorimetry (DSC), X-ray diffractometry (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and polarized light microscopy (PLM), in addition to in vitro dissolution in pH 6.8. The screening results indicated intermolecular interactions occurring between NVP and 3TC; NVP and CAc, where shifts in the melting temperature of NVP were verified. The presence of CAc impacted the NVP equilibrium solubility, due to hydrogen bonds. DSC thermograms evidenced the reduction and shifting of the endothermic peaks of NVP in the presence of its co-formers, suggesting partial miscibility of the compounds. Amorphization was proven by XRD and PLM assays. In vitro dissolution study exhibited a significant increase in solubility and dissolution efficiency of NVP-CAM compared to free NVP. Combined use of screening studies was useful for the development of stable and amorphous NVP-CAM, with increased NVP solubility, making CAM promising systems for combined antiretroviral therapy.

Clinical Evaluation of the Effect of Nanohydroxyapatite Lozenge on the pH of Dental Plaque.

This study investigated the influence of nanohydroxyapatite-containing (nanoHAP) lozenge on plaque pH following sucrose intake. Sixteen adult subjects were enrolled in this double-blind crossover study composed of four interventions: (1) 10% w/v sucrose solution, (2) 10% w/v sorbitol solution, (3) nanoHAP lozenge, and (4) 10% w/v sucrose solution challenge followed by nanoHAP lozenge. Following the determination of each subject's resting plaque pH, the pH was measured at different time intervals from 3 to 30 minutes from the start of intervention, with 7 days interval between the applications of different interventions. The data were analyzed using the analysis of variance and Tukey's test (α < 0.05). While sorbitol produces no change in plaque pH, nanoHAP-lozenge increased the plaque pH from a baseline of 7.0 ± 0.3 (mean ± sd) to 7.8 ± 0.2 (mean ± sd) within 30 minutes. Sucrose lowered the plaque pH from a baseline of 7.0 ± 0.4 (mean ± sd) to the lowest minimum of 5.1 ± 0.1 (mean ± sd) at the 7th minute, rising above the critical pH of enamel dissolution (5.5) at 12th minute and the baseline pH in more than 30 minutes. With lozenge intervention following sucrose challenge, plaque pH rose to 5.5 in 8 min, and to the baseline pH in 24 min. The cH area (Hydrogen ion concentration area) produced by sucrose (1.82 sq. units) was significantly (p < 0.05) greater than that produced when sucrose was challenged with lozenge (0.48 sq. units). Nanohydroxyapatite-containing lozenge increased plaque pH, reduced plaque pH drop in the presence of sucrose, and facilitated the rapid recovery of plaque pH after sucrose intake.

Hydroxypropyl methylcellulose phthalate films reinforced with nanocrystalline cassava starch and intended its applications for colonic drug delivery

Controlled-release drug delivery systems are crucial for improving therapeutic efficacy and patient compliance. Hydroxypropyl methylcellulose phthalate (HPMCP) films are promising candidates due to their film-forming properties and tunable release profiles. However, their mechanical properties can limit their applicability. This study aimed to assess the effect of addition of nanocrystalline cassava (NCS) starches to HPMCP films on the physicochemical and mechanical properties and the ability of films to control drug release rate. Reinforced HPMCP films with 2, 4 and 6 % w/w of NCS were characterized as a function of the microstructure, X-ray diffraction pattern, mechanical properties, and dissolution property. It was found that increasing starch amount induced an increase in heterogeneity of the film microstructure and crystallinity. The tensile strength of HPMCP films increased with addition of starches, while the elongation at break decreased. The lowest dissolution in pH 6.8 phosphate buffer solution was found for films containing NCS at 2 and 4 % w/w. For the application purposes, HPMCP containing different amounts of NCS was used to coat over diclofenac sodium tablets. The tablets coated with HPMCP containing 4 % w/w NCS showed the lowest drug release of 73.5 % in pH 6.8 phosphate buffer solution at 240 min. According to our results, the addition of NCS at adequate amount allowed to improve the mechanical properties of HPMCP films and to decrease the drug release rate which is important for the site-specific drug delivery process.

Ferrous Pyrophosphate and Mixed Divalent Pyrophosphates as Delivery Systems for Essential Minerals.

Poorly water-soluble iron-containing compounds are promising iron fortificants. However, ensuring high bioaccessibility and low reactivity of iron is challenging. We present the potential application of ferrous pyrophosphate (Fe(II)PP) and Fe(II)-containing M2(1-x)Fe2x P2O7 salts (0 < x < 1, M = Ca, Zn, or Mn) for delivery of iron and a second essential mineral (M). After preparation by a facile and environment-friendly coprecipitation method, the salts were investigated for their composition, pH-dependent dissolution, iron-mediated discoloration of a black tea solution, and oxidation of vitamin C. Our results suggest that these salts are possible dual-fortificants with tunable composition that compared to Fe(II)PP (i) show lower (<0.5 mM) and enhanced (to 5 mM) iron dissolution in moderate and gastric pH, respectively, (ii) exhibit less discoloration and dissolved iron in tea when x = 0.470 for M = Ca or Zn and x = 0.086 for M = Mn, and (iii) do not increase the oxidation extent of vitamin C over 48 h when x = 0.06, 0.086, or 0.053 for M = Ca, Zn, or Mn, respectively.

Sorption of Pt(II) on inactive biomass of Aspergillus Niger O-5 treated with cetyltrimethylammonium bromide

Platinum-group cytostatic have been found in natural waters due to the current inefficiency of wastewaters treatment plants. This study was aimed to the assessment of inactive biomass of Aspergillus niger O-5 treated with cetyltrimethylammonium bromide as sorbent for solid phase extraction of [PtCl4]2-complex from aqueous dissolutions for the subsequent development of new water treatment technologies. Maximum sorption capacity of 54 mg·g−1 was achieved at 25 °C under the following experimental conditions: pH of dissolution = 5, biomass mass = 10 mg, dissolution volume = 10 mL, Pt(II) mass = 0.5 mg and contact time = 30 min. The good fitting of the model of Ho and the increase of sorption capacity up to 102 mg·g−1 with temperature suggested the chemisorption as predominant mechanism. The mean free energy of adsorption was higher than 8 kJ·mol−1 for all temperatures, which also indicated the chemical character of the interaction. The absolute value of the standard molar Gibbs free energy of formation increased from 3.032 to 8.336 kJ· mol−1 with temperature signifying that the sorption was thermodynamically favored, occurred spontaneously and the degree of spontaneity increased with temperature. The positive value (32.3 kJ·mol−1) of the standard molar enthalpy qualified the sorption as an endothermic process, after which the adsorbent/sorbate system became more thermodynamically stable.

Dissolution and antioxidant potential of apigenin self nanoemulsifying drug delivery system (SNEDDS) for oral delivery

Self-nanoemulsifying drug delivery systems (SNEDDS) have been used to improve the oral bioavailability of various drugs. In the current study, apigenin was developed as SNEDDS to solve its dissolution problem and enhance oral bioavailability and antioxidant potential. SNEDDS were prepared by mixing Gelucire 44/14, Tween 80, and PEG 400 under controlled conditions. The droplet of diluted SNEDDS demonstrated a spherical shape with a size of less than 100 nm and a neutral charge. The very fast self-emulsification was obtained within 32 s, and the transmittance values exceeded 99%. The highest drug loading was 90.10 ± 0.24% of the initial load with the highest %encapsulation efficiency of 84.20 ± 0.03%. FT-IR and DSC spectra showed no interaction between components. The dissolution in buffer pH 1.2, 4.5, and 6.8 showed significantly higher dissolved apigenin than the apigenin coarse powder. The dissolution profiles were fitted to the Korsmeyer–Peppas kinetics. The cellular antioxidant activities in Caco-2 cells were approximately 52.25–54.64% compared to no treatment and were higher than the apigenin coarse powder (12.70%). Our work highlights the potential of SNEDDS to enhance the dissolution and permeability of apigenin and promote antioxidant efficacy, which has a strong chance of being developed as a bioactive compound for nutraceuticals.

Stabilizing BiVO4 Photoanode in Bicarbonate Electrolyte for Efficient Photoelectrocatalytic Alcohol Oxidation.

In order to expand the application of bismuth vanadate (BiVO4) to the field of photoelectrochemistry, researchers have explored the potential of BiVO4 in catalyzing or degrading organic substances, potentially presenting a green and eco-friendly solution. A study was conducted to investigate the impact of electrolytes on the photocatalysis of benzyl alcohol by BiVO4. The research discovered that, in an acetonitrile electrolyte (pH 9) with sodium bicarbonate, BiVO4 catalyzed benzyl alcohol by introducing saturated V5+. This innovation addressed the issue of benzyl alcohol being susceptible to catalysis in an alkaline setting, as V5+ was prone to dissolution in pH 9 on BiVO4. The concern of the photocorrosion of BiVO4 was mitigated through two approaches. Firstly, the incorporation of a non-aqueous medium inhibited the formation of active material intermediates, reducing the susceptibility of the electrode surface to photocorrosion. Secondly, the presence of saturated V5+ further deterred the leaching of V5+. Concurrently, the production of carbonate radicals by bicarbonate played a vital role in catalyzing benzyl alcohol. The results show that, in this system, BiVO4 has the potential to oxidize benzyl alcohol by photocatalysis.

Control of Dental Caries in Children and Adolescents Using Fluoride: An Overview of Community-Level Fluoridation Methods.

The maintenance of oral health is a crucial aspect of general well-being; however, a significant proportion of the worldwide population experiences a range of oral diseases. Dental caries is a highly prevalent non-communicable disease globally, especially in children and adolescents. Fluoride is involved in the control of dental caries, primarily by decreasing the critical pH for dental hard tissue dissolution and decreasing enamel solubility. Due to the substantial data supporting the efficacy of fluoride in controlling dental caries, many community-level fluoridation initiatives have been devised and executed as global public health preventive interventions. These initiatives encompass the fluoridation of water, salt, and milk. Water fluoridation is considered safe and effective when fluoride levels are maintained within the recommended range (0.6 to 1.1 mg/L). Salt fluoridation has a cariostatic potential similar to that of water fluoridation, and a fluoride concentration of 250 micrograms per gram in salt is not associated with an increased risk of developing dental fluorosis. However, there is currently an effort to reduce the consumption of table salt in order to mitigate the harmful effects of excessive salt consumption. It has been hypothesized that fluoride food supplementation, such as fluoridated milk, is associated with a decrease in caries experience in permanent teeth; however, the effect is not clear in primary teeth. Public-level fluoride interventions are more cost-effective than the operative care of caries lesions and limit the burden of care. The administration of fluorides should be conducted using safe methods, limiting ingestion, and adhering to the guidelines set by international and national health agencies in each country. This is particularly important when considering children with developing dentitions. Fluoride is an important tool in the control of dental caries, but it is crucial to combine it with good oral hygiene, a healthy diet, and regular visits to a dental professional to maintain long-term oral health.

Chitosan-TPP microcapsules for controlled drug release

Production of chitosan/sodium tripolyphosphate (CS/TPP) microcapsules via spray drying involves atomizing an emulsion containing CS, TPP, acetic acid (AcOH), and folic acid (FA) into fine droplets exposed to high-temperature, low-pressure gas flow. Solvent evaporation within the drying chamber leads to solid particle formation. Spray drying is valuable for creating solid CS/TPP microcapsules. Precise equipment parameter adjustments, like inlet temperature and gas flow rate, enable the study of microcapsule morphology, size, and properties. This adaptability allows for customization to specific pH dissolution ranges. The production method's impact on CS/TPP microcapsules was studied by modifying spray drier parameters, including inlet temperature and aspirator pressure, to enhance understanding of their behavior in solution under varied production conditions.&#x0D; In chitosan delivery systems, various approaches can encapsulate drug agents like folic acid, an analog to the cancer treatment drug methotrexate. Agents can be added to the chitosan solution pre-crosslinking, incorporated into gelation-inducing agents pre-mixing with chitosan, or included in the crosslinking mixture. Experiments were conducted to assess CS/TPP microcapsules' behavior when encapsulating agents like folic acid. Release profiles were analyzed to understand their drug delivery capabilities and potential as controlled release carriers.

Rice husk ash as sorbent for solid phase extraction of diclofenac, ibuprofen and carboplatin residues from waters

Carboplatin, ibuprofen and diclofenac are among drugs classified as emergent pharmaceutical contaminants that impact negatively the environment. Development of affordable procedures for their quantification and removal from waters is gained interest in the scientific community. The present study was aimed at the characterization of rice husk ash as sorbent for the solid phase extraction of mentioned drugs in waters. Optimal sorbent dose, pH dissolution and contact time were selected. Up to the best of our knowledge, the good performance of rice husk ash for extraction of carboplatin, ibuprofen and diclofenac from aqueous dissolutions is demonstrated for the first time in the present study, achieving a maximum sorption capacity of 5.843 mg.g−1, 2.321 mg.g−1 and 2.316 mg.g−1, respectively, which are higher than those reported for others pharmaceutical products with husk rice ashes. Kinetic of sorption was well modeled by a Lagergren pseudo first order model for diclofenac and by a pseudo second order model of Ho for ibuprofen and carboplatin. Sorption at equilibrium conditions was well modeled by Freundlich and Toth isotherms for diclofenac and ibuprofen, while Sips, Toth and Dubinin-Radushkevich isotherms adjusted well for carboplatin. Kinetic and at equilibrium conditions studies confirmed the high complexity of involved sorption mechanisms in the three adsorbate/rice husk ash systems considered.

Study on Electrochemical Behavior of Oxidized Pyrite in Alkaline Electrolyte

Nowadays, refractory gold ore production around the world accounts for about 30% of total gold production, and the low leaching rate of such gold concentrate seriously limits the efficient utilization of gold resources. The alkaline preoxidation process can improve the leaching rate of this kind of gold deposit and has good development and application prospects. Therefore, it is of great significance to study the oxidation and dissolution behavior of pyrite in an alkaline environment. In this paper, the oxidation process of gold-bearing pyrite in an alkaline electrolyte was studied using electrochemical techniques, and the oxidation products of a pyrite electrode in an alkaline solution were characterized using XPS, SEM, and other analytical methods. The results show that the optimum pH for pyrite electrochemical oxidative dissolution is about 12, and the oxidation potential of pyrite should be above 0.8 V. In the process of alkaline oxidative dissolution of pyrite, part of the S element enters the electrolyte in the forms of Sx2−, S2O32−, SO32−, and SO42−, and a small amount of the S element is adsorbed on the surface of the electrode in the form of S0 and becomes a part of the passive layer. The Fe element is adsorbed on the surface of the electrode in the forms of Fe(OH)2, Fe2O3, and Fe2(SO4)3, which become the main components of the passivation layer. This study provides a theoretical basis and reference data for the chemical preoxidation treatment of gold-bearing sulfide ores.

Effects of vegetation restoration on distribution characteristics of heavy metals in soil in Karst plateau area of Guizhou.

In southwest China, vegetation restoration is widely used in karst rocky desertification control projects. This technology can effectively fix the easily lost soil, gradually restore the plant community and improve soil fertility. However, the change law of soil heavy metals in the restoration process remains to be further studied. Therefore, in this work, Guizhou Caohai Nature Reserve as a typical karst area was taken as the research object to investigate the influence of vegetation restoration technology on repairing soil heavy metal pollution. The spatial distribution characteristics of soil heavy metals (chromium, nickel, arsenic, zinc, lead) before and after vegetation restoration in karst area were studied by comparative analysis and linear stepwise regression analysis. The main influencing factors and spatial distribution characteristics of heavy metals in karst area were further discussed. The results showed that: (1) heavy metals in karst soils are affected by surface vegetation, root exudates, microorganisms and leaching. Only heavy metals nickel (Ni) and lead (Pb) showed the tendency of surface enrichment and bottom precipitation enrichment in non-karst soils. Path analysis suggested that non-metallic soil factors such as soil bulk density (BD), total nitrogen (TN) and ammonium nitrogen (NH4 +-N) had direct effect on the content of heavy metals in soil. (2) The proportion of 0.25-2 mm aggregates in the surface soil of vegetation restoration belt was more than 40%, and the proportion of surface soil ≤2 mm aggregates in this increased to 83% and 88%, respectively, which could improve the soil structure and properties effectively. (3) Vegetation restoration effectively restored the nutrient elements such as carbon and nitrogen in the soil, and enhanced the soil material circulation. Furthermore the content of heavy metals in the surface soil higher than that in the 10-20 cm soil layer. Plant absorption, biosorption mechanism of microorganisms, coupling of root exudates, dissolution of soil soluble organic carbon and pH make the contents of heavy metals Cr, Ni and Pb in vegetation restoration belt slightly lower than those in karst soil. At the same time, affected by vegetation coverage, residual heavy metals in soil are further leached by surface runoff. Therefore, the content of heavy metals in soil could reduce combined heavy metal enrichment plants for extraction with remediation. This study elucidates the advantages and remedy mechanism of vegetation restoration in the remediation of heavy metal contaminated soils in Caohai area of Guizhou, and this plant activation and enrichment extraction remediation technology would be popularized and applied in the remediation of heavy metal contaminated soils in other karst areas.

Investigating the Role of Classical Ayurveda-Based Incineration Process on the Synthesis of Zinc Oxide Based Jasada Bhasma Nanoparticles and Zn2+ Bioavailability.

Jasada bhasma (JB) is a zinc oxide-based Indian traditional Ayurveda-based herbo-metallic nanoparticle used for the treatment of zinc (Zn) deficiency and autoimmune and inflammatory disorders. JB is made by following the Ayurveda-based guidelines using zinc oxide (ZnO) as a raw material and going through 17 cycles of the high-temperature incineration and trituration process known as "Ma̅raṇa" in the presence of herbal decoctions prepared from the leaves ofAzadirachta indica andAloe vera gel. These cycles improve the purity of the parent material and transform its physicochemical properties, converting it into nanoparticles. However, there still exists a knowledge gap regarding the role of incineration in the physicochemical transformation of the Zn raw material into JB nanoparticles and the biological interaction of the final product. In the present study, the JB samples obtained during different Ma̅raṇa cycles were carefully studied for their physicochemical transformation using analytical methods such as powdered X-ray diffraction (XRD), small-angle X-ray scattering (SAXS), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy, Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, and dynamic light scattering (DLS). According to the XRD results, the Zn and oxygen molecules in hexagonal ZnO wurtzite crystals gradually realigned as a result of repeated heat treatments that caused lattice tension and crystal size reduction from 53.14 to 42.40 nm. A morphological transition from 1.5 μm rod shape to 31 nm in the JB particles can be seen using FESEM and SAXS analyses. The existence of 10 nm-sized nanoparticles in the finished product was confirmed by HRTEM. The presence of ZnO was confirmed in all samples by FTIR and Raman spectroscopies. Cell viability analysis showed an inhibitory concentration 50% of >1000 μg/mL for JB nanoparticles, revealing no adverse effects in human colon Caco-2 cells. A dose-dependent uptake and intracellular accumulation of JB nanoparticles were observed in Caco-2 cells using inductively coupled plasma-based mass spectroscopy (ICP-MS). Bioavailability of Zn2+ ions (6% w/w) through JB dissolution in acidic pH 4.0 was observed, representing the stomach and intracellular lysosomal physiological conditions. Therefore, the study showed that the repeated incineration cycles produced biocompatible JB nanoparticles through the physicochemical transformation at molecular levels capable of delivering bioavailable Zn2+ ions under physiological conditions. In conclusion, the medicinal properties of JB nanoparticles described in Ayurveda were found to originate from their small size and dissolution properties, formed through the classical incineration-based synthesis process.

Evaluation of pH and total soluble solid (ºbrix) on the cariogenic and erosive potential of milk powder infantile formula

The objective of this study is to analyze the influence of pH and the amount of Total Soluble Solids on the ºBrix scale on the cariogenic and erosive potential of powdered infant formula. This is a laboratory study with 5 brands of powdered infant formula for children aged 6 to 36 months. Brands with intact packaging, stored in cool places and within the expiry date for consumption were included. Obtaining the Brixº was performed by refractometer and pH with a pHmeter with a cycle of three repetitions. Of the five brands tested, the sugar levels on the ºBrix scale were between 10.67 and 12.0, with all maras having total carbohydrate values ​​between 9.0 and 14.0 g, which are considered healthy. Regarding the pH, four had a pH lower than 7, being considered acidic and all above the critical pH (5.5) for dissolution of dental structures. It was concluded that by measuring pH and sugars on the Brixº scale, the brands analyzed were within acceptable standards for maintaining oral health, making these two factors positive determinants so as not to influence the cariogenic and/or erosive potential of milk powder infant formula.

Hydrogen‐bonded polymer multilayer coatings via dynamic layer‐by‐layer assembly

AbstractWe developed the dynamic assembly of the hydrogen‐bonded multilayers of (poly(N‐vinylpyrrolidone/poly(methacrylic acid)) (PVPON/PMAA)) and compared their properties to the static multilayers. We found that dynamic multilayers, wherein a planar substrate is shaken during polymer adsorption, leads to a 15‐time faster deposition of the planar coatings. The thicknesses and roughness of the dynamic coatings were found to be ⁓30% larger than those of static (no shaking) multilayer films as measured by spectroscopic ellipsometry and atomic force microscopy. We examined the film growth, mechanical properties, wettability, hydration, and pH stability of the planar static and dynamic multilayers and demonstrated that these properties were insignificantly affected by the assembly mode. Both static and dynamic coatings produced microporous films when exposed to pH = 5.9, close to the film critical dissolution pH = 6. We discovered that during the release of the multilayer films into a solution to produce free‐standing films either as planar membranes or multilayer capsule shells, the molecular chain rearrangements result in the decreased roughness for both static and dynamic multilayers and lead to a decreased thickness of the dynamic multilayers. Our findings can help develop a rapid synthesis of thicker nanostructured polymer coatings for sensing and controlled delivery applications.

A Comparative Study on Gold Dissolution in Broad pH Range from Acidic to Alkaline Media

Gold is often employed in nanotechnology to develop biosensors and new drug delivery and cancer therapy strategies. Since these applications are used in physiological pH, understanding the stability of gold in a broader pH range including neutral values will provide an useful insight into how to expand the use of gold safely.By using buffer solutions with a constant concentration of phosphate species, electrochemical dissolution of gold in pH 1, 3, 5, 7, 9, 11 and 12.7 was investigated. The concentration of phosphate species was kept constant in order to minimize the possible effect of anion concentration on gold dissolution. Oxidation/reduction of the metal surface leads to transient dissolution peaks, which are labelled as A1 and C1 on the dissolution profiles on Figure 1. An additional dissolution peak A2 appears when the oxygen evolution reaction (OER) takes place. Quantitatively, there are significant differences. The amount of gold that is transiently dissolved in an alkaline medium is more than an order of magnitude higher than that in an acidic medium at lower potentials. Oppositely, steady-state gold dissolution in alkaline pH in the potential region of OER is hindered. There is an apparent shift in the mechanisms at pH 5. At higher potentials, i.e 1.9 V RHE, there is an apparent loss of peak A2 and a growth of C1. The loss of dissolution of gold due to a change in the mechanism of OER in more alkaline electrolytes is clear at pH 7. To explain the observed difference in gold dissolution, a difference in the thickness of compact oxide formed in acid and base is suggested. The formation of thicker oxide as a result of an increase in pH becomes noticeable with the observed increase in both peaks A1 and C1 that can be seen when the pH is increased from 7 to 12.7. These new data on Au dissolution in a broad potential and pH range should be used to minimize Au dissolution in various applications. Figure 1

Genesis of uranium containing groundwater in the Brahmaputra floodplain of Assam: Hydrogeochemistry and its associated health risk

Groundwater uranium (U) content and the major hydrogeochemical processes were evaluated for six districts of Assam, lying mostly on the central and northern region of the Brahmaputra floodplain. A total of 504 groundwater samples were collected using the grid sampling technique. Uranium concentrations analysed using LED fluorimeter model LF-2a, ranged from below detection limit (BDL) to 13.5 μgL−1. All the U concentrations were found to be well below the prescribed limits of AERB, WHO and USEPA. The highest groundwater U was recorded in a sample from Nagaon, a central Brahmaputra floodplain district. The SEM-EDX spectra of the sediment samples revealed geogenic presence of U in the floodplain. A comparative assessment between the relationships of U with other groundwater parameters revealed that shallow aquifers provided more feasibility for elemental interactions and hence more mobility of U species. The correlation statistics in shallow aquifers depicted the importance of alkalinity on U release and mobilization. Uranium release during weathering of the geological strata was signified by the relationship of U with EC, TDS and salinity. The role played by pH and ORP in dissolution of U in the floodplain was not strong. The dominant water type in the study was Mg–HCO3, which was associated with higher U concentration. This revealed the positive role of carbonate dissolution towards U release in the floodplain. Hydrogeochemical investigation further implied for greater silicate weathering and ion exchange compared to that of carbonate weathering and reverse ion exchange processes. The calculated undersaturation of calcite, dolomite and gypsum explained their role as source minerals in the floodplain. Uranium dissolution and mobilization was found to have positive association with carbonate weathering, as depicted by its significant relationship with calcite, dolomite and gypsum. Health risk, both radiological and chemical, relating to U ingestion through drinking water was absent within the floodplain.

Glycine-mediated leaching-mineralization cycle for CO2 sequestration and CaCO3 production from coal fly ash: Dual functions of glycine as a proton donor and receptor

The state-of-the-art CO2 mineralization technologies involved Ca/Mg leaching and ensued mineralization still struggle with the slow reaction kinetics and frequent pH swings assisted by exogenous chemicals consumption (i.e., low pH for Ca/Mg leaching but high pH for CO2 dissolution and solid carbonates precipitation). This study proposed a glycine-mediated leaching-mineralization cycle (LMC) process, which can simultaneously achieve promising Ca/Mg leaching efficiency, high mineral carbonation efficiency, and production of high-purity CaCO3 from coal fly ash (CFA) at mild operating conditions in an in-situ recyclable amino acid solution. The technical feasibility of the process was initially investigated in individual leaching and mineral carbonation experiments in glycine (Gly0) solutions using a typical CFA. A Ca2+ leaching efficiency of 42.17% and a CaCO3 yield of 89.10 g/kg were achieved in the Gly0 solution. Mineralogy and morphology analysis revealed that the CaCO3 obtained after the carbonation reaction was mainly present as vaterite. The mechanism exploration revealed that Gly-species acted as a proton donor and chelating agent in the leaching step which enhanced the Ca2+ leaching, a proton receptor in mineralization step which accelerated CO2 mass transfer, and a crystal regulator in carbonates precipitation. In addition, the cyclic performance of the LMC process was investigated in multicycle leaching-carbonation experiments. Results showed that the leaching capacities, CaCO3 yield, and Gly0 loss were similar in five cycles of LMC experiments, verifying that the process is stable.

A pilot study on the effect of desferrioxamine B on uranium VI precipitation and dissolution in pH 11.5, 0.1\xa0M NaCl solutions

A pilot study investigating the possible role of desferrioxamine B (DFOB) to prevent UVI precipitation in alkaline NaCl solutions was carried out. Desferrioxamine B is a hydroxamate siderophore occurring naturally in the environment. The siderophore can possibly mobilize UVI from a wide range of sources such as mine tailings, contaminated land and radioactive waste storage and disposal facilities. The results from a series of batch experiments covering a wide range of naturally occurring concentrations over relevant time scales (3 days and 2 months) show that DFOB can quantitatively prevent UVI precipitation as ≥ 0.2 μm precipitates when 130 µM and 420 µM of the DFOB is present in solution. The impact is minimized as its concentration decrease to below 10 µM, suggesting these ligands will have a less mobilizing effect on uranium from a geological disposal facility if present in its VI oxidation state.

A pharmacokinetic and pharmacodynamic evaluation of colchicine sustained-release pellets for preventing gout

Gout is a common metabolic disease caused by the chronic deposition of monosodium urate (MSU) crystals in joints and tissues. Low-dose of colchicine (COL) has become the first-line drug for clinical prevention of acute gout attacks. However, their high cytotoxicity leads to a narrow therapeutic index and frequent toxic reactions. This study developed colchicine sustained-release pellets (COL-SRPs) using fluidized-bed technology to overcome the shortcomings of fluctuation in blood concentration and other side effects of commercial rapid release COL preparations. The COL-SRPs showed a smooth surface and spherical shape under a scanning electron microscope (SEM). The in vitro release curves of the COL-SRPs under different pH dissolution medium were not significantly different (similarity factors 2 ˃ 50). The release of COL from pellets may be a diffuse action. Pharmacokinetic studies demonstrated that the mean residence time (MRT) and tmax of the COL-SRPs group were significantly higher than those in the commercial colchicine tablets (COL-Ts) group. Pharmacodynamic studies comprehensively evaluated serum inflammatory factor indicators (IL-1β and TNF-α), liver and kidney function indexes (ALT, AST and CRE), as well as ankle joint histopathology, further suggesting that the COL-SRPs exhibited a more optimal preventive potential against acute gout attack. The COL-SRPs prepared in this study provide a powerful alternative to commercial COL-Ts by overcoming their shortcomings and having great industrial production potential.