Citrate Ratio Research Articles

Treatment of an Azo Dye by Citrate Catalyzed Photoelectro-Fenton Process Under Visible Light using Carbon Nanotube-polytetrafluoroethylene Cathode

Degradation of C.I. Direct Red 23 (DR23) was investigated by photoelectro-Fenton (PEF) process in the presence of citrate catalyst under visible light irradiation of 6W. Multi walled carbon nanotubes (CNTs) were characterized by transmission electron microscopy (TEM), which had approximately internal and external diameters of 6 nm and 22 nm, respectively. CNTs were stabilized on carbon paper utilizing polytetrafluoroethylene (PTFE) and stabilization was confirmed by scanning electron microscopy (SEM). Results revealed that the degradation efficiency followed the order of PEF/citrate > PEF > EF at the same operational conditions after 90 min treatment of 20 mg/L DR23. The effect of some operational parameters such as applied current, initial pH, initial dye concentration and Fe(III) to citrate ratio on PEF/citrate process was studied. Artificial neural network (ANN) was applied not only to develop a model to predict the degradation efficiency with reasonable performance (R2= 0.988), but also to determine the relative importance of operational parameters for PEF/citrate process.

Spermine and Citrate as Metabolic Biomarkers for Assessing Prostate Cancer Aggressiveness

Separating indolent from aggressive prostate cancer is an important clinical challenge for identifying patients eligible for active surveillance, thereby reducing the risk of overtreatment. The purpose of this study was to assess prostate cancer aggressiveness by metabolic profiling of prostatectomy tissue and to identify specific metabolites as biomarkers for aggressiveness. Prostate tissue samples (n = 158, 48 patients) with a high cancer content (mean: 61.8%) were obtained using a new harvesting method, and metabolic profiles of samples representing different Gleason scores (GS) were acquired by high resolution magic angle spinning magnetic resonance spectroscopy (HR-MAS). Multivariate analysis (PLS, PLS-DA) and absolute quantification (LCModel) were used to examine the ability to predict cancer aggressiveness by comparing low grade (GS = 6, n = 30) and high grade (GS≥7, n = 81) cancer with normal adjacent tissue (n = 47). High grade cancer tissue was distinguished from low grade cancer tissue by decreased concentrations of spermine (p = 0.0044) and citrate (p = 7.73·10−4), and an increase in the clinically applied (total choline+creatine+polyamines)/citrate (CCP/C) ratio (p = 2.17·10−4). The metabolic profiles were significantly correlated to the GS obtained from each tissue sample (r = 0.71), and cancer tissue could be distinguished from normal tissue with sensitivity 86.9% and specificity 85.2%. Overall, our findings show that metabolic profiling can separate aggressive from indolent prostate cancer. This holds promise for the benefit of applying in vivo magnetic resonance spectroscopy (MRS) within clinical MR imaging investigations, and HR-MAS analysis of transrectal ultrasound-guided biopsies has a potential as an additional diagnostic tool.

Nano-scaled hierarchical porous ZnO nanostructures: fabrication and application in dye-sensitized solar cells

Three-dimensional (3D) hierarchical porous ZnO architectures constructed by sheet-like structures were prepared through calcination of a bilamellar basic zinc citrate intermediate. The molar ratio of citrate anion/Zn2+ and the pH value of the reaction solution play crucial roles in the formation of the 3D hierarchical nanostructures. On the basis of the synthetic experimental results, a growth mechanism is proposed in the case of citrate as the organic ligand. The resulting nano-scaled porous ZnO structures exhibit a high specific surface area up to 55.6 m2 g−1 with a pore size of 5.1 nm. A light-to-electricity conversion efficiency of 4.46% was achieved of the dye-sensitized solar cells with the porous ZnO as the photoanode.

STRUCTURAL PROPERTIES AND MICROSTRUCTURE OF COBALT FERRITE PARTICLES SYNTHESIZED BY A SOL-GEL AUTO COMBUSTION METHOD

Synthesis and characterization of Cobalt ferrite powders by a sol gel combustion process is focused in the present work. The prepared precursors was calcined at 950° C for 4 hours in order to get cobalt ferrite powder. The effect of metal nitrates/citric acid ratio (referred as x) of CoFe2O4 on structural and micro-structural properties was investigated. The structural characterization on CoFe2O4 ferrite samples were carried out using the X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR) techniques. Phase identification and crystallite size of calcined powder were determined using XRD analysis. The formation of the ferrite is confirmed by FTIR results. The morphology of prepared CoFe2O4 ferrite samples (with x = 0.5, 1.0, 1.5 and 2.0, where x is metal to citrate ratio) was studied using a scanning electron microscopy.

A new binuclear Cr(III) citrate anion: Synthesis, characterization and crystal structure of [Cr(CO(NH2)2)6]2[Cr2(CO(NH2)2)2(C6H4O7)2

Abstract The new anion [Cr2(CO(NH2)2)2(C6H4O7)2]2 − has been isolated in the complex [Cr(CO(NH2)2)6]2[Cr2(CO(NH2)2)2(C6H4O7)2]3. The crystals of this complex were obtained by a one-pot synthetic method using 1:1 molar ratio of hexaureachromium(III) chloride and trisodium citrate in aqueous medium. It was characterized by elemental analysis, IR spectroscopy and single crystal X-ray diffraction analysis. The compound crystallizes in space group R‾3 of the trigonal system with three formula units in a cell of dimensions a = b = 24.7461(4) A, c = 13.7204(3) A and γ = 120°. The crystal structure comprises the columns consisting of [Cr(CO(NH2)2)6]3 + cations surrounded by a cylinder of complex anions, [Cr2(CO(NH2)2)2(C6H4O7)2]2 − which are packed in a honeycomb-like manner. This supramolecular architecture is formed and stabilized by inter- and intramolecular N H⋯O hydrogen bonds.

Importance of citrate and the calcium : citrate ratio in patients with calcium renal lithiasis and severe lithogenesis

Different studies have shown the importance of citrate in the formation of calcium stones. It has further been shown that the states of metabolic acidosis result in an increase in bone resorption and lower urinary citrate levels. Increasing the intake of citrate in these patients can reduce the lithogenic risk and improve bone mineral density (BMD), contributing to control of both diseases. The study shows the importance of citrate in patients with calcium stones and BMD loss. The deficit in citrate excretion is associated with a decrease in bone mineralization and increased β-crosslaps. A calcium : citrate ratio >0.25 in patients with calcium stones and loss of mineral density may predict severe lithogenic activity. To analyse the importance of urinary citrate and the urinary calcium : citrate ratio in patients with calcium renal lithiasis and severe lithogenesis compared with a control group of patients without lithiasis. A cross-sectional study of 115 patients in eastern Andalusia, Spain was conducted. The patients were divided into two groups: Group A: 56 patients aged 25-60 years without calcium renal lithiasis; Group B: 59 patients aged 25-60 years, presenting with calcium renal lithiasis and severe lithogenesis. The citrate levels and the calcium : citrate ratio in the patients' urine and the relationship of these two factors to lithiasic activity were analysed and compared. In Group B, 32.2% of the patients presented with hypocitraturia, compared with 14.3% of the patients in Group A (P = 0.02). The urinary citrate levels were lower in Group B than in Group A (P = 0.001) and the calcium : citrate ratio was higher in Group B than in Group A (P = 0.005). The results suggest that a patient urinary calcium : citrate ratio > 0.25 indicates severe lithogenesis (with a sensitivity of 89% and a specificity of 57%). After linear regression analysis, we found that the urinary citrate level is an independent factor associated with the changes in bone densitometry T-score values of patients. The patients with severe lithogenesis presented with hypocitraturia, which was associated with lower bone mineral density. The calcium : citrate ratio, which is linearly related to the bone resorption marker β-crosslaps, could be useful in evaluating the risk of severe lithogenesis when this ratio is >0.25.

Importance of citrate and the calcium : citrate ratio in patients with calcium renal lithiasis and severe lithogenesis

Stone disease and osteopaenia are both common conditions, and reduced bone mineral density (BMD) is an increasingly recognized complication in stone formers; indeed, in a previous paper in BJUI, Arrabal-Polo et al. 1 reported that patients with recurrent stones have lower BMD compared with controls or patients with just a single episode of urolithiasis. Although the exact pathogenesis of bone loss in stone disease is yet to be determined, the conceptually obvious relationship with hypercalciuria is well documented 2. In the present study, Arrabal-Polo et al. emphasise that hypocitraturia is also associated with reduced BMD. Furthermore, they found a higher calcium : citrate ratio in patients with a cumulative maximum stone diameter >20 mm, or in those with frequent recurrences than in controls, and found that this correlated with higher levels of β-crosslaps, consistent with increased bone resorption in these patients. We commented in our previous editorial that metabolic abnormalities should be sought in recurrent stone formers, and managed in a multi-disciplinary setting 3. In addition to dietary advice, options for treatment include bisphosphonates (which inhibit bone resorption, and are commonly used in osteoporosis), thiazide diuretics (which reduce calcium excretion and can increase BMD) and potassium citrate (which acts as an alkalinizing agent mitigating the bone restorative effect of acidosis) 2. This approach is supported by recent data in medullary sponge kidneys, in which hypercalciuria and hypocitraturia were commonly detected in association with reduced BMD. Patients who were treated with potassium citrate were found to have increased urinary pH citrate levels, and an improvement in their BMD 4. In the present article, Arrabal-Polo et al. suggest using a calcium : citrate ratio of 0.25 for predicting the risk of future recurrent stone formation, but this value could equally be used to predict the risk of patients having reduced BMD and the complications that may follow. Either way, their findings strengthen the argument for metabolic screening of recurrent stone formers, and for an assessment of these patients' BMD. Patients can then be appropriately treated with a thiazide diuretic, potassium citrate, or a bisphosphonate, either singly or in combination, according to the abnormalities detected and their progress on treatment.

SPARC promotes the development of erythroid progenitors

Secreted protein acidic and rich in cysteine (SPARC) is a well-recognized regulator that affects cell proliferation, differentiation, and survival. Here, we investigated the impact of SPARC on erythropoiesis. Erythropoiesis in bone marrow (BM) from SPARC(-/-) mice was analyzed by flow cytometry and colony-forming assays. The mechanisms that affected erythropoiesis were investigated by BM transplantation experiments. CD34(+) cells from umbilical cord blood were isolated by MiniMACS, and the effect of SPARC on human erythropoiesis was assessed by colony-formation assay and erythroid differentiation culture. The hemoglobin level in peripheral blood (PB) was lower in SPARC(-/-) mice. Neither red blood cell count in PB nor the percentage of Ter119(+) erythrocytes in BM showed significant difference between SPARC(-/-) and WT mice. However, the ability of SPARC(-/-) bone marrow cells (BMCs) to form erythroid burst-forming units (BFU-E), as well as spleen colony-forming units (CFU-S8), was significantly decreased. The addition of exogenous SPARC could promote the formation of BFU-E from SPARC(-/-) BMCs in vitro. And the impaired ability of SPARC(-/-) BMCs to form BFU-E could be restored by transplanted into WT BM microenvironment, whereas the BFU-E formation of WT BMCs was impaired after transplanted into SPARC(-/-) recipients. Furthermore, exogenous SPARC promoted umbilical cord blood CD34(+) cells to form erythroid colonies and the hemoglobinization of erythroid, but did not affect the expression levels of glycophorin A and CD71. In conclusion, our results indicate that SPARC promotes the development of erythroid progenitors, but does not affect terminal erythroid differentiation.

Effect of Fe(III)/Citrate Concentrations and Ratio on the Photoproduction of Hydroxyl Radicals: Application on the Degradation of Diphenhydramine

Fe(III)-citrate complexes are photoreactive and ubiquitous in natural waters. In this study, the effect of Fe(III)/citrate concentrations and ratio on the photoproduction of •OH as a function of pH...

MR spectroscopic imaging and diffusion‐weighted imaging of prostate cancer with Gleason scores

To investigate functional changes in prostate cancer patients with three pathologically proven different Gleason scores (GS) (3+3, 3+4, and 4+3) using magnetic resonance spectroscopic imaging (MRSI) and diffusion-weighted imaging (DWI). In this study MRSI and DWI data were acquired in 41 prostate cancer patients using a 1.5T MRI scanner with a body matrix combined with an endorectal coil. The metabolite ratios of (Cho+Cr)/Cit were calculated from the peak integrals of total choline (Cho), creatine (Cr), and citrate (Cit) in MRSI. Apparent diffusion coefficient (ADC) values were derived from DWI for three groups of Gleason scores. The sensitivity and specificity of MRSI and DWI in patients were calculated using receiver operating characteristic curve (ROC) analysis. The mean and standard deviation of (Cho+Cr)/Cit ratios of GS 3+3, GS 3+4, and GS 4+3 were: 0.44 ± 0.02, 0.56 ± 0.06, and 0.88 ± 0.11, respectively. For the DWI, the mean and standard deviation of ADC values in GS 3+3, GS 3+4, and GS 4+3 were: 1.13 ± 0.11, 0.97 ± 0.10, and 0.83 ± 0.08 mm(2) /sec, respectively. Statistical significances were observed between the GS and metabolite ratio as well as ADC values and GS. Combined MRSI and DWI helps identify the presence and the proportion of aggressive cancer (ie, Gleason grade 4) that might not be apparent on biopsy sampling. This information can guide subsequent rebiopsy management, especially for active surveillance programs.

Degradation of diuron by persulfate activated with ferrous ion

The degradation of diuron by persulfate (S2O82−, PS) activated with ferrous ion (Fe2+) was investigated. The PS–Fe2+ system achieved high levels of reduction of diuron (90%). The optimal PS/Fe2+ molar ratio for diuron reduction was found to be 1:1. A chelating agent, sodium citrate, was used to control the amount of Fe2+ in solution for activation of the oxidant, with the optimum results obtained when the molar ratio of citrate and Fe2+ was 1:1. A reductive chemical, hydroxylamine, was also applied into the PS–Fe2+ system, and the hydroxylamine/Fe2+ molar ratio of 2:1 significantly increased the degradation of diuron due to enhancement of redox of Fe3+ to Fe2+. The main degradation product of diuron was 1-(3,4-Dichlorophenyl)-3-methylurea(DCPMU); SO4− attack did not cause the opening of the aromatic ring of diuron.

Synthesis, Sintering, Transport Properties, and Surface Exchange of La2Ni0.9Cu0.1O4+δ

Dense La2Ni0.9Cu0.1O4+δ ceramics were sintered from powders synthesized through a wet‐chemical citrate nitrate route with optimized ratios of citrate to nitrate. Less citrate decreases the required sintering temperature and improves the oxygen permeativity. The oxygen permeation was measured as a function of oxygen activity gradient, membrane thickness (0.4–2.6 mm) and temperature (800°C–950°C). The oxygen self diffusion coefficient DO and the surface exchange coefficient k show Arrhenius‐type behaviors with activation energies of ~50 and ~100 kJ/mol, respectively. The oxygen chemical diffusion coefficient Dchem and surface exchange coefficient kchem, measured by conductivity relaxation, exhibit Arrhenius‐type behaviors with activation energies of 62 and 104 kJ/mol, respectively. Dchem and kchem are related to DO and k through the thermodynamic factor ωO.

CONTROLLING THE SIZE AND SIZE DISTRIBUTION OF GOLD NANOPARTICLES: A DESIGN OF EXPERIMENT STUDY

The Turkevich method is the oldest and most widely employed protocol for the production of colloidal gold. Gold nanoparticles are nontoxic in nature and have potential applications in various biomedical fields including drug delivery and bioimaging. These metallic nanoparticles can be functionalized with drugs, targeting ligands such as tumor necrosis factor and groups (e.g., Poly ethylene glycol) to provide shielding from undesired immune responses. In this study we investigate the influence of process variables on the synthesis of nanoparticles by the reduction of chloroauric acid ( HAuCl4 ) solution with sodium citrate. A design of experiment (DoE) approach was used to investigate the influence of production volume, temperature, stirring rate and sodium citrate concentration on the physical properties of the nanoparticles namely size, size distribution, zeta potential and UV-Vis characteristics. The study showed that the relative amount of sodium citrate added ( Au /citrate mole ratio) had a significant effect on the size, poly dispersity index (PDI), the number of peaks in the size distribution and the position of Lambda max in the UV-Vis spectra. By varying the Au /Citrate ratio it is possible to synthesize particles with average diameters from 20 to 80 nm. However, the use of low amounts of sodium citrate in order to produce particles larger than ~35 nm tends to result in a wide bimodal size distribution.

Antioxidant properties of polysaccharide from the brown seaweed Sargassum graminifolium (Turn.), and its effects on calcium oxalate crystallization.

We investigated the effects of polysaccharides from the brown seaweed Sargassum graminifolium (Turn.) (SGP) on calcium oxalate crystallization, and determined its antioxidant activities. To examine the effects of SGP on calcium oxalate crystallization, we monitored nucleation and aggregation of calcium oxalate monohydrate crystals, using trisodium citrate as a positive control. We assessed antioxidant activities of SGP by determining its reducing power, its ability to scavenge superoxide radicals, and its activity in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. The nucleation inhibition ratio of trisodium citrate and SGP was 58.5 and 69.2%, respectively, and crystal aggregation was inhibited by 71.4 and 76.8%, respectively. Increasing concentrations of SGP resulted in increased scavenging of superoxide anions and DPPH radicals (IC50 = 1.9 and 0.6 mg/mL, respectively). These results suggest that SGP could be a candidate for treating urinary stones because of its ability to inhibit calcium oxalate crystallization and its antioxidant properties.

Curium(iii) citrate speciation in biological systems: a europium(iii) assisted spectroscopic and quantum chemical study

Citrate complexes are the dominant binding form of trivalent actinides and lanthanides in human urine at pH < 6. Hence, an accurate prediction of the speciation of these elements in the presence of citrate is crucial for the understanding of their impact on the metabolism of the human organism and the corresponding health risks. We studied the complexation of Cm(III) and Eu(III), as representatives of trivalent actinides and lanthanides, respectively, in aqueous citrate solution over a wide pH range using time-resolved laser-induced fluorescence spectroscopy. Four distinct citrate complexes were identified and their stability constants were determined, which are MHCit(0), M(HCitH)HCit(2-), M(HCit)(2)(3-), and M(Cit)(2)(5-) (M = Cm, Eu). Additionally, there were also indications for the formation of MCit(-) complexes. Structural details on the EuHCit(0) and EuCit(-) complexes were obtained with FT-IR spectroscopy in combination with density functional theory calculations. IR spectroscopic evidence for the deprotonation of the hydroxyl group of the citrate ion in the EuCit(-) complex is presented, which also revealed that the complexation of the Eu(3+) ion takes place not only through the carboxylate groups, like in EuHCit(0), but additionally via the hydroxylate group. In both EuHCit(0) and EuCit(-) the carboxylate binding mode is mono-dentate. Under a very low metal : citrate ratio that is typical for human body fluids, the Cm(III) and Eu(III) speciation was found to be strongly pH-dependent. The Cm(III) and Eu(III) citrate complexes dominant in human urine at pH < 6 were identified to be Cm(HCitH)HCit(2-) and a mixture of Eu(HCitH)HCit(2-) and EuHCit(0). The results specify our previous in vitro study using natural human urine samples (Heller et al., Chem. Res. Toxicol., 2011, 24, 193-203).

Preparation of Calcium Carbonate Superfine Powder by Calcium Carbide Residue

Calcium carbonate superfine powder with high purity was prepared from calcium carbide residue by a liquid phase process using ammonium chloride as extraction agent and ammonium carbonate agent. The effects of some factors on the reaction were investigated. The calcium carbonate was characterized by X-ray powder diffraction device (XRD) and scanning electron microscopy (SEM). The optimum preparation conditions were determined as follows: the concentration of calcium ion 0.3mol/L, The mass ratio of ammonium citrate and calcium ion 0.1, temperature of carbonization 10°C The product is calcium carbonate of single crystal structure with the diameter of 40-90nm.

Tuning the size of gold nanoparticles in the citrate reduction by chloride ions

A new approach was developed to control the size of gold nanoparticles in citrate reduction by altering the concentration of chloride ions. The size of the as-prepared gold nanoparticles could be tuned in the range 19-47 nm at a specific molar ratio of citrate and tetrachloroauric acid (5:1) by simply changing the concentration of chloride ions from 0 to 20 mM. UV-visible spectra and TEM observations showed that the increased size of the gold particles was primarily related to the promoted aggregation of the primary gold particles. The aggregation was attributed to their decreased surface charge as the chloride ion concentration in the reaction solutions increased. This approach could also be extended to other reaction systems, for example, the size of gold nanoparticles prepared by NaBH(4) reduction increased from 3 to 12 nm as the chloride ion concentration was increased from 0 to 20 mM.

One-pot deposition of palladium on hybrid TiO2 nanoparticles and catalytic applications in hydrogenation

One-pot deposition of Pd onto TiO2 has been achieved through directly contacting palladium(II) salt with nanosized functionalized TiO2 support initially obtained by sol–gel process using titanium isopropoxide and citric acid. Citrate groups act as functional moieties able to directly reduce the Pd salt avoiding any further reducing treatment. Various palladium salts (Na2PdCl4 and Pd(NH3)4Cl2·H2O) and titanium to citrate (Ti/CA) ratios (20, 50, and 100) were used in order to study the effect of the nature of the precursor and of the citrate content on the final Pd particle size and catalytic properties of the as-obtained Pd/TiO2 systems. Characterization was performed using N2 adsorption–desorption isotherms, ICP-AES, FTIR, XRD, XPS, and TEM. The as-obtained hybrid Pd/TiO2 catalysts were tested in the selective hydrogenation (HYD) of an α,β-unsaturated aldehyde, i.e. cinnamaldehyde. Citrate-free Pd/TiO2-based catalysts present lower selectivity into saturated alcohol. However, citrate-functionalized Pd/TiO2 catalyst seems to control the selectivity, the particle size and dispersion of Pd NPs leading to high intrinsic activity.

Renal function and kidney length in preterm infants with nephrocalcinosis: a longitudinal study

Renal injury in early life may lead to hypertension and renal disease in adulthood. In this prospective study, we estimated renal glomerular and tubular function and kidney length (KL) during the first 2 years of life of preterm infants with nephrocalcinosis (NC) associated with prematurity. The study cohort comprised 107 preterm children, 63 with NC and 44 control subjects without NC who were matched for gender, gestational age and birth weight. Kidney function was estimated based on measurements of serum creatinine (Scr), estimated glomerular filtration rate (eGFR), fractional excretion (FE) of sodium (Na), potassium (K), phosphate (P), magnesium (Mg) and uric acid (UA) and on the ratios of urinary Ca, oxalate (UOx) and citrate (UCit) to urinary creatinine (UCa/Ucr, UOx/Ucr and UCit/Ucr, respectively) calculated from morning urine collections. KL was measured by ultrasonography. Measurements were made at 40 weeks postmenstrual age and at 3, 6, 12 and 24 months of age. At 3 and 6 months, the NC group had higher UCa/Ucr, FEK and FEUA than the control group; at 12 months, only the UCa/Ucr and FEUA was still higher. The UCa/UCit ratio was higher in the NC group. Scr and eGFR did not differ between the groups at any time point. The NC group had a shorter KL up to 12 months of life (left kidney) or 24 months (right kidney). Based on these results, we conclude that NC in the preterm infants enrolled in our study was associated with impaired renal tubular function and a shorter KL in the first year of life.

Reproducibility of 3D 1H MR spectroscopic imaging of the prostate at 1.5T

To determine the reproducibility of 3D proton magnetic resonance spectroscopic imaging ((1)H-MRSI) of the human prostate in a multicenter setting at 1.5T. Fourteen subjects were measured twice with 3D point-resolved spectroscopy (PRESS) (1)H-MRSI using an endorectal coil. MRSI voxels were selected in the peripheral zone and combined central gland at the same location in the prostate in both measurements. Voxels with approved spectral quality were included to calculate Bland-Altman parameters for reproducibility from the choline plus creatine to citrate ratio (CC/C). The repeated spectroscopic data were also evaluated with a standardized clinical scoring system. A total of 74 voxels were included for reproducibility analysis. The complete range of biologically interesting CC/C ratios was covered. The overall within-voxel standard deviation (SD) of the CC/C ratio of the repeated measurements was 0.13. This value is equal to the between-subject SD of noncancer prostate tissue. In >90% of the voxels the standardized clinical score did not differ relevantly between the measurements. Repeated measurements of in vivo 3D (1)H-MRSI of the complete prostate at 1.5T produce equal and quantitative results. The reproducibility of the technique is high enough to provide it as a reliable tool in assessing tumor presence in the prostate.