Mixture Of Citrate Research Articles

Magnetic Mesoporous Carbons Derived from in Situ MgO Template Formation for Fast Removal of Heavy Metal Ions.

In this paper, magnetic mesoporous carbon composites were prepared by calcination of the mixture of magnesium citrate and Fe3O4@SiO2 in an inert atmosphere. A high content of Fe3O4@SiO2 and MgO was in situ embedded in a carbon matrix. After removing the MgO template by diluted acid, the resulting material (Fe3O4@SiO2@mC) was subjected to further H2O2 oxidation treatment. The formed oxygen-containing functional groups on the products provided plenty of active sites for the adsorption of analytes of interest. The obtained composites (Fe3O4@SiO2@mC-H2O2) exhibited a mesoporous structure with a high specific surface area of 731 m2 g–1. The adsorption capacities of Fe3O4@SiO2@mC-H2O2 for Cu(II) and Pb(II) were calculated to be 86.5 and 156 mg g–1, respectively. Under optimal conditions, the adsorption isotherm of Cu(II) and Pb(II) onto Fe3O4@SiO2@mC-H2O2 fitted the Langmuir model and the adsorption kinetic was well-correlated with the pseudo-second-order model. Besides, Fe3O4@SiO2@mC-H2O2 exhibited fast removal dynamics (within less than 1 min) for Cu(II) and Pb(II), demonstrating great application potential in wastewater treatment.

Toxicological interactions induced by chronic exposure to gold nanoparticles and microplastics mixtures in Daphnia magna

The effects of emerging environmental contaminants on human and environmental health is of high concern, especially those potentially induced by mixtures. The main goal of the present study was to assess the chronic effects of mixtures of citrate stabilized ≈5 nm gold nanoparticles (AuNP) and 1–5μm microplastics (MP) on Daphnia magna. A 21-day bioassay was carried out. The effect criteria were parental mortality, somatic growth and several reproductive parameters. AuNP induced parental mortality, reduced the total offspring and caused immobile juveniles and aborted eggs. MP induced parental mortality, delayed the first brood release, decreased the number of broods released, the total offspring, and caused immobile juveniles. All the mixtures caused higher toxicity than AuNP and MP alone. Based on parental mortality, evidences of antagonism between AuNP and MP were observed at low concentrations of both mixture components, whereas evidences of synergism at high concentrations were found. Chronic (21-day) exposure of D. magna to AuNPs, MP, and their mixtures can impair development, reproduction, ultimately leading to death.

Treatment and Prevention of Urolithiasis in patients with stones of various locations

The study goal was to find the most optimal approach to the treatment of patients with urolithiasis. The study involved 4014 patients with stones of different localization. Patients with benign prostatic hyperplas-ia (BPH) were investigated with IPSS, PSA, and uroflowmetry. 3175 ureteropyeloscopies were performed. Separately, we studied the results of treatment of 427 patients with ureterolithiasis in combination with BPH, which underwent ureterolithotripsy. Percutaneous nephrolithotrip-sy was performed in 412 patients, most of the procedures were per-formed according to the classical technique. The other research purpose was prophylaxis optimization of the recurrent urolithiasis. 152 patients participated in the experimental part. Some of the patients were taken from the clinical part of the study. All patients were with recurrent calci-um oxalate urolithiasis. Patients were divided into two groups: the 1st group (74 patients) did not receive treatment during the follow-up peri-od, the second group (42 patients) received treatment in the volume of thiazide diuretics, water load, citrate mixtures, calcium preparations in-side. During the entire follow-up (6 months), all patients underwent a comprehensive urological examination. Eventually have been estimated that surgery should not be the final stage of treatment of the urolithiasis. Urolithiasis requires constant monitoring of patients, and the priority task of a urologist is to prevent recurrent stone formation. This is achieved through the appointment of adequate conservative therapy, which includes thiazide diuretics, citrate mixtures, calcium preparations, water intake in adequate amount, and if necessary, magnesium prepara-tions. The final choice of conservative treatment depends on the type of stone. The change in the concentration of crystallization inhibitors (biku-nin and osteopontin) is a predictor of an early relapse of the urolithiasis, which can be used in monitoring patients in the postoperative period.

Facile synthesis and lithium storage properties of engineered ultrafine porous Fe2SiO4/C composites

Engineered ultrafine porous Fe2SiO4/C composites (FS221/C, FS263/C and FS325/C) are successfully fabricated by solid state reactions from the mixture of ammonium citrate, ferrous oxalate dehydrate and nano porous SiO2 with different specific surface area (221, 263 and 325m2g−1). XRD results proved that α-Fe2SiO4 phase are formed in the three samples. SEM and TEM results indicate that all the three samples are ultrafine composites and the particle size of FS325/C is the smallest. Pore structure analysis indicates that the external surface area of the ultrafine porous Fe2SiO4/C composites can be well controlled by tuning the surface area of nano porous SiO2 and the external surface area of FS325/C is the largest among the three samples. These unique features make FS325/C possess the highest reversible lithium storage capacity, best rate performance, longest cycling life, lowest charge transfer resistance and highest lithium ion diffusion coefficient among the three samples.

Development and Evaluation of Mesalamine—Glutamine Cocrystal Tablets for Colon Specific Delivery


 The objective of the work was to develop the co-crystal formulation of mesalamine with glutamine. It was done to enhance dissolution rate, solubility and physicochemical properties to be used in pharmaceutical composition (tablet) for colon targeting. Co-crystal preparation was carried out by liquid assisted grinding method using glutamine as a co-crystal former (1:1 stoichiometric ratio) and acetonitrile as a solvent giving maximum solubility and dissolution rate. The formation of the co-crystals was confirmed by Fourier Transform – Infra Red spectrometry, Differential Scanning Calorimetry and Powder X-Ray Diffraction. Pre-compression studies included measure-ment of bulk density, tapped density, angle of repose, Hausner’s ratio and compressibility index. The tablets were prepared by direct compression. Post compression parameters for uncoated tablets included hardness, size and thickness, friability and weight variation. Enteric-coated tablets were prepared by dip-coating process using Eudragit RSPO, Triethyl citrate and isopropyl alcohol mixture as coating solution. The coated tablets were further evaluated for disintegration and dissolution testing. All the results were found to be under specified limits. Finally, co-crystal tablets were compared with marketed formulation. In vitro dissolution rate of optimized mesalamine co-crystal tablet was comparatively higher than marketed formulation, which reflects improvement in solubility. Glutamine has good anti-inflammatory property. Formulation with glutamine as co-crystal added more efficacies to mesalamine for treatment in colon related inflammatory diseases. It was concluded that stable co-crystals of mesalamine -glutamine having better anti-inflammatory property, increased solubility and improved in vitro dissolution of mesalamine can be successfully prepared. 

On the nature of citrate-derived surface species on Ag nanoparticles: Insights from X-ray photoelectron spectroscopy

Abstract Citrate is an important stabilizing, reducing, and complexing reagent in the wet chemical synthesis of nanoparticles of silver and other metals, however, the exact nature of adsorbates, and its mechanism of action are still uncertain. Here, we applied X-ray photoelectron spectroscopy, soft X-ray absorption near-edge spectroscopy, and other techniques in order to determine the surface composition and to specify the citrate-related species at Ag nanoparticles immobilized from the dense hydrosol prepared using room-temperature reduction of aqueous Ag+ ions with ferrous ions and citrate as stabilizer (Carey Lea method). It was found that, contrary to the common view, the species adsorbed on the Ag nanoparticles are, in large part, products of citrate decomposition comprising an alcohol group and one or two carboxylate bound to the surface Ag, and minor unbound carboxylate group; these may also be mixtures of citrate with lower molecular weight anions. No ketone groups were specified, and very minor surface Ag(I) and Fe (mainly, ferric oxyhydroxides) species were detected. Moreover, the adsorbates were different at AgNPs having various size and shape. The relation between the capping and the particle growth, colloidal stability of the high-concentration sol and properties of AgNPs is briefly considered.

Volumetric, acoustic and spectroscopic studies (FT-IR) of trisodium (TSC) and tripotassium citrate (TPC) in aqueous solution of ionic liquid 1-butyl-3-methylimidazolium tetrafluoro borate [C4mim][BF4] at different temperatures

In this work, density ρ, and speed of sound u, for citrate salts trisodium citrate (TSC) and tripotassium citrate (TPC) have been measured in (0.005, 0.01, 0.03 and 0.05) mol·kg−1 aqueous solution of ionic liquid 1-butyl-3-methylimidazolium tetrafluoro borate ([C4mim][BF4]) at different temperatures T=(288.15, 293.15, 298.15, 303.15, 308.15) K at experimental pressure p=0.1MPa. Different parameters such as apparent molar volume (Vϕ), partial molar volume (Vϕ0), and standard partial molar volumes of transfer (ΔVϕ0) have been calculated by using the experimental density data. From experimental speed of sound data apparent molar isentropic compression (Kϕ,s), partial molar isentropic compression (Kϕ,so), and partial molar isentropic compression of transfer (ΔKϕ,so) have been calculated. The pair and triplet interaction coefficients have been calculated from transfer parameters. Infrared spectral studies have also been carried out for the present mixtures. Work is mainly concerned with the study of the interactions present in the mixtures of trisodium citrate and tripotassium citrate in aqueous solutions of ionic liquid 1-butyl-3-methylimidazolium tetrafluoro borate [C4mim][BF4].

One-step pyrolysis route to three dimensional nitrogen-doped porous carbon as anode materials for microbial fuel cells

The design and synthesis of low-cost and favourable anode materials is crucial to both power production efficiency and overall performance of microbial fuel cells (MFCs). Herein, we reported the preparation of three dimensional (3D) nitrogen-doped porous carbons (N/PCs) by one-step pyrolysis of solid mixture of sodium citrate and melamine. a variety of techniques, including electron microscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), etc., were applied to characterize the surface physicochemical properties of the products, featuring macroporous structure with rich nitrogen doping on the as-prepared N/PCs. When applied as anode materials of MFC, the N/PCs exhibits a maximum power density of 2777.7mWm−2, approximately twice higher than that of the MFCs with the commercial carbon cloth (CC) as anode. The significantly improved performance of the N/PCs was attributed to the unique structure and properties, such as favourable porous structure, good electrical conductivity, and large pore volume (0.7cm3g−1) in the present N/PCs. Nitrogen dopant on the surface of porous carbon contributed to an increasing in biocompatibility, resulting in a suitable micro-environment for microbial growth and thus helps to decrease charge transfer resistance at the electrode interface.

Determination of vitamin B12 via pH-dependent quenching of the fluorescence of nitrogen doped carbon quantum dots

Highly stable, hydrophilic carbon quantum dots (CQDs) with a fluorescence quantum yield of 43% were prepared by dehydration/condensation and aromatization/carbonization of a mixture of diethylenetriamine and trisodium citrate. The CQDs possess a mixed crystalline and polycrystalline structure in the basic and acidic medium respectively. The fluorescence of the CQDs (with excitation/emission peaks at 390/450 nm) arises from both the CQDs and from molecular fluorophores incorporated in the CQDs and is highly pH dependent in the range between pH 2.0 and 9.0. Fluorescence is strongly quenched by vitamin B12 (VitB12). This finding is exploited in a quenchometric method for the quantification of VitB12 that works in the VitB12 concentration range between 1 nM to 20 μM, and the lower limit of detection is 210 pM.

Temperature dependence of the volumetric and acoustic behaviour of aqueous mixtures of monosaccharides and trilithium citrate

Densities (ρ) and speeds of sound (c) measurements of d(−)-ribose and d(+)-xylose in (0.2, 0.4, 0.6) mol·kg−1 aqueous solutions of trilithium citrate (TLC) have been carried out at different temperatures. The experimental results were used to calculate apparent molar and partial molar quantities, partial molar volumes and partial molar isentropic compression of transfer. The pair and triplet interaction coefficients are computed from transfer parameters. The partial molar expansibilities have also been calculated. The results have been interpreted in terms of prevailing interactions and structure making and breaking tendency of the solutes in aqueous solution of TLC.

CURRENT STUDIES OF THE EFFICACY OF CITRATE THERAPY FOR URIC ACID NEPHROLITHIASIS IN RUSSIA

Urolithiasis is a common urological disease the prevalence of which tends to increase. The main targets of therapy for patients with uric acid nephrolithiasis include normalization of purine metabolism, dissolution of stones, and prevention of stone formation. Oral administration of a citrate mixture or sodium bicarbonate results in urine alkalinization and dissolution of the uric acid stone. The article demonstrates the results of the recent Russian studies of the efficacy and safety of litholytic therapy for uric acid nephrolithiasis both as monotherapy and in combination with remote lithotripsy. The studies show that citrate therapy is a highly effective, non-invasive method for the treatment and metaphylaxis of uric acid nephrolithiasis.

Kinetics of hydrochemical deposition of PbSe films in the presence of ascorbic acid

The boundary conditions of the formation of PbSe and concomitant impurity phases, Pb(OH)2 and PbCN2, were determined by calculation of the ionic equilibria in the Pb2+–Na3C5Н6О7–CH4N2Se system. Complex kinetic studies of the PbSe deposition from an ammonia–citrate mixture containing ascorbic acid as antioxidant for selenourea were performed. PbSe films 250 to 425 nm thick were synthesized by the hydrochemical method based on the results obtained. The absence of impurities in the deposited samples was confirmed by X-ray diffraction analysis.

Cofortification of ferric pyrophosphate and citric acid/trisodium citrate into extruded rice grains doubles iron bioavailability through in situ generation of soluble ferric pyrophosphate citrate complexes

Iron fortification of rice is a promising strategy for improving iron nutrition. However, it is technically challenging because rice is consumed as intact grains, and ferric pyrophosphate (FePP), which is usually used for rice fortification, has low bioavailability. We investigated whether the addition of a citric acid/trisodium citrate (CA/TSC) mixture before extrusion increases iron absorption in humans from FePP-fortified extruded rice grains. We conducted an iron absorption study in iron-sufficient young women (n = 20), in which each participant consumed 4 different meals (4 mg Fe/meal): 1) extruded FePP-fortified rice (No CA/TSC); 2) extruded FePP-fortified rice with CA/TSC added before extrusion (CA/TSC extruded); 3) extruded FePP-fortified rice with CA/TSC solution added after cooking and before consumption (CA/TSC solution); and 4) nonextruded rice fortified with a FeSO4 solution added after cooking and before consumption (reference). Iron absorption was calculated from erythrocyte incorporation of stable iron isotopes 14 d after administration. In in vitro experiments, we assessed the soluble and dialyzable iron from rice meals in which CA/TSC was added at different preparation stages and from meals with different iron:CA:TSC ratios. Fractional iron absorption was significantly higher from CA/TSC-extruded meals (3.2%) than from No CA/TSC (1.7%) and CA/TSC solution (1.7%; all P < 0.05) and was not different from the FeSO4 reference meal (3.4%). In vitro solubility and dialyzability were higher in CA/TSC-extruded rice than in rice with No CA/TSC and CA/TSC solution, and solubility increased with higher amounts of added CA and TSC in extruded rice. Iron bioavailability nearly doubled when CA/TSC was extruded with FePP into fortified rice, resulting in iron bioavailability comparable to that of FeSO4 We attribute this effect to an in situ generation of soluble FePP citrate moieties during extrusion and/or cooking because of the close physical proximity of FePP and CA/TSC in the extruded rice matrix. This trial was registered at clinicaltrials.gov as NCT02176759.

Sequential SERS determination of aspirin and vitamin C using in situ laser-induced photochemical silver substrate synthesis in a moving flow cell.

In this contribution, the utility of sequential injection analysis in combination with surface-enhanced Raman spectroscopy (SERS) as a detection technique was investigated for simultaneous determination of aspirin and vitamin C in their pharmaceutical dosage forms and in spiked urine samples. The silver substrate was synthesized in situ by laser-induced photochemical procedure. By focusing the laser on a flow cell at 1ml/min of continuous flow of 0.5mM silver nitrate and 5mM sodium citrate mixture, an active silver spot on the inner wall of the flow cell was prepared in a few seconds. The whole setup is fully computer controlled using ATLAS software to combine the two techniques. The system allows sequential determination of aspirin concentrations ranging from 100 to 500ng/ml and vitamin C concentrations between 10 and 110ng/ml with good precision of relative standard deviations (RSDs) of 0.85 and 1.7%, respectively. A comparison of these results with those of the reported procedures showed excellent results compared with t and F values, indicating good accuracy and precision. The detection limits were 32 and 3ng/ml for aspirin and vitamin C, respectively.

Simultaneous Determination of Ternary Mixture of Aspirin, Caffeine and Orphenadrine Citrate by Simple RP-TLC Spectrodensitometric Method

Aims: A simple TLC Spectrodensitometric method was developed for analysis of Orphenadrine Citrate (OR), Caffeine (CAF) and Aspirin (ASP) either in pure form or in their pharmaceutical preparations. Study Design: Validation study. Methodology: In this method, The three drugs were separated on silica gel plate using ethyl acetate: acetone: methanol: triethylamine (6:3:1:0.2, by Volume) as mobile phase at room temperature. Many experimental parameters such as band size, slit width, different developing mobile phases and scanning wavelengths were examined and the optimum conditions were selected. The obtained bands were then scanned at 220 nm. The three drugs were adequately resolved with the R­­f values of ASP (Rf = 0.08 ± 0.02), CAF (Rf = 0.55 ± 0.02) and OR (Rf = 0.35 ± 0.02). Validation parameters of the developed method were studied like linearity, accuracy, precision, and specificity. Results: Linearity of the proposed method was found to be in the concentration ranges 0.4-2 μg/band for ASP, 0.4-2 μg/band for CAF and 0.3-3 μg/band for OR. Conclusion: The suggested method was effectively used for analysis of ASP, CAF and OR in pure form and in their medicinal formulations. The method is proved to be specific, accurate and selective.

Facile synthesis of carbon nanofibers-bridged porous carbon nanosheets for high-performance supercapacitors

A facile and one-step method is demonstrated to prepare carbon nanofibers (CNFs)-bridged porous carbon nanosheets (PCNs) through carbonization of the mixture of bacterial cellulose and potassium citrate. The CNFs bridge PCNs to form integrated porous carbon architecture with high specific surface area of 1037 m2 g−1, much higher than those of pure PCNs (381 m2 g−1) and CNFs (510 m2 g−1). As a consequence, the PCN/CNF composite displays high specific capacitance of 261 F g−1, excellent rate capability and outstanding cycling stability (97.6% of capacitance retention after 10000 cycles). Moreover, the assembled symmetric supercapacitor with PCN/CNF electrodes delivers an ultrahigh energy density of 20.4 Wh kg−1 and outstanding cycling life (94.8% capacitance retention after 10000 cycles) in an aqueous electrolyte.

Synthesis of Cu-doped nano-TiO2 by detonation method

Cu-doped nano-TiO2 was successfully prepared by detonating a mixture of metatitanic acid, cupric citrate, ethylene glycol, and hexogen with specific mass ratio in a closed container. The samples were characterized using an X-ray diffractometer (XRD), transmission electron microscope, high-resolution transmission electron microscope, energy dispersive x-ray spectrometer, UV–vis spectrophotometer, and FTIR spectrophotometer. Results showed that the samples comprising the mixed crystal of anatase and rutile were the most irregularly shaped particles, exhibiting poor dispersion. The 550°C high-temperature heat treatment could improve the dispersion, with crystal size of 10–30nm. The diffraction peak of the copper oxide appeared on the XRD pattern with the increase in Cu doping concentration. Cu doping could reduce the band gap of TiO2 and enhance visible light absorption. New absorption peaks appeared on the infrared absorption spectrum of TiO2 after Cu doping, and energy levels were observed in the energy gap of TiO2. The photocatalytic properties of TiO2 could be enhanced by increasing the Cu doping concentration. The initial concentration of methyl orange solution negatively correlated with the photocatalytic properties of TiO2, whereas the degradation rate of methyl orange solution increased with increasing TiO2 dosage. An almost linear relationship was observed between TiO2 dosage and degradation rate. The concentration of the Cu-doped sample had a significant impact on the degradation rate of methyl orange solution.

Temperature-Dependent Conversion of Magnesium Citrate into Nanoporous Carbon Materials for Superior Supercapacitor Application by a Multitemplate Carbonization Method

A straightforward multitemplate carbonization method for producing nanoporous carbons has been implemented using magnesium citrate as the carbon source and magnesium powder as the template. Notably, the crystallinities of the carbon materials were greatly enhanced with increasing carbonization temperatures. Sample C-4:1–900 obtained by carbonizing the mixture of magnesium citrate and Mg powder (in a mass ratio of 4:1) at 900 °C exhibited a large BET surface area of 1972.1 m2 g–1 and a high pore volume of 4.78 cm3 g–1, thereby resulting in the best electrochemical behaviors. It delivered a large specific capacitance of 236.5 F g–1 at 1 A g–1 when measured in a three-electrode system. Additionally, in a two-electrode system, the energy density was 15 Wh kg–1 for a power density of 0.5 W kg–1, when measured at an operating temperature of 80 °C.

Efficacy of Mixtures of Magnesium, Citrate and Phytate as Calcium Oxalate Crystallization Inhibitors in Urine

The main aim of the current study was to evaluate the effectiveness of mixtures of magnesium, citrate and phytate as calcium oxalate crystallization inhibitors. A turbidimetric assay in synthetic urine was performed to obtain induction times for calcium oxalate crystallization in the absence and presence of different mixtures of inhibitors. The morphology of calcium oxalate crystals in the absence or presence of inhibitors and mixtures of the inhibitors was evaluated in 2 crystallization experiments at low and high calcium oxalate supersaturation. The crystals formed were examined using scanning electron microscopy. Examination of crystallization induction times revealed clear inhibitory effects of magnesium, citrate and phytate on calcium oxalate crystallization, supporting usefulness in the treatment and prevention of calcium oxalate nephrolithiasis. Significant synergistic effects between magnesium and phytate were observed. Scanning electron microscopy images revealed that phytate is a powerful crystal growth inhibitor of calcium oxalate, totally preventing the formation of trihydrate and monohydrate. In addition to crystallization inhibition capacity, citrate and magnesium avoided calcium oxalate crystallization by decreasing its supersaturation. The synergistic effect between magnesium and phytate on calcium oxalate crystallization suggests that a combination of these 2 compounds may be highly useful as antilithiasis therapy.

Heat-Stable Dry Powder Oxytocin Formulations for Delivery by Oral Inhalation.

In this work, heat stable dry powders of oxytocin (OT) suitable for delivery by oral inhalation were prepared. The OT dry powders were prepared by spray drying using excipients chosen to promote OT stability including trehalose, isoleucine, polyvinylpyrrolidone, citrate (sodium citrate and citric acid), and zinc salts (zinc chloride and zinc citrate). Characterization by laser diffraction indicated that the OT dry powders had a median particle size of 2 μm, making them suitable for delivery by inhalation. Aerodynamic performance upon discharge from proprietary dry powder inhalers was evaluated by Andersen cascade impaction (ACI) and in an anatomically correct airway (ACA) model, and confirmed that the powders had excellent aerodynamic performance, with respirable fractions up to 77% (ACI, 30 L/min). Physicochemical characterization demonstrated that the powders were amorphous (X-ray diffraction) with high glass transition temperature (modulated differential scanning calorimetry, MDSC), suggesting the potential for stabilization of the OT in a glassy amorphous matrix. OT assay and impurity profile were conducted by reverse phase HPLC and liquid chromatography-mass spectrometry (LC-MS) after storage up to 32 weeks at 40°C/75%RH. Analysis demonstrated that OT dry powders containing a mixture of citrate and zinc salts retained more than 90% of initial assay after 32 weeks storage and showed significant reduction in dimers and trisulfide formation (up to threefold reduction compared to control).