Concentrations Of LaCl3 Research Articles

A new method for preparation of RE2(CO3)3 by multi-membrane electroconversion

Preparing rare earth carbonates from rare earth chlorides is a common step in the smelting process for all rare earth ores; however, it produces large amounts of ammoniacal nitrogen wastewater and a chloride-rich precipitate. This study proposes a novel, green and simple process for preparing low-chlorine lanthanum carbonate via a multi-membrane electroconversion approach. The effects of the CO2 flow rate, current density, lanthanum chloride concentration, and electroconversion time on the electroconversion process were systematically explored. Under the optimal process conditions (CO2 flow rate = 0.5 L/min, current density = 25 mA/cm2, LaCl3 concentration = 0.3 mol/L, electroconversion time = 60 min), a current efficiency of 75.77% was obtained, along with a unit energy consumption of 5.44 kW h/kg. X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, and laser particle size analysis results indicate that a pure La2(CO3)3·8H2O product is obtained with a median particle size of 6.53 μm and chlorine content of 0.0021%. In addition, scanning electron microscopy and transmission electron microscopy observations indicate that the crystallisation and growth of La2(CO3)3·8H2O conform to the oriented attachment and Ostwald ripening mechanisms. Thus, the proposed multi-membrane electroconversion method provides guidance toward the clean transformation of rare earth chlorides to low-chlorine lanthanum carbonates.

Lanthanum Significantly Contributes to the Growth of the Fine Roots' Morphology and Phosphorus Uptake Efficiency by Increasing the Yield and Quality of Glycyrrhiza uralensis Taproots.

The occurrence of different degrees of phosphorus deficiency in the vast majority of G. uralensis cultivation regions worldwide is common. There is a pressing need within the cultivated G. uralensis industry to identify appropriate exogenous substances that can enhance the uptake of phosphorus and improve both the yield and quality of the taproots of G. uralensis. This study was conducted to investigate the fine root and taproot morphology, physiological characteristics, and secondary metabolite accumulation in response to the supply of varying concentrations of LaCl3 to G. uralensis, to determine the optimal concentration of LaCl3 that can effectively enhance the yield and quality of G. uralensis's taproots, while also alleviating its reliance on soil phosphate fertilizer. The findings indicate that the foliar application of lanthanum enhanced root activity and increased APase activity, eliciting alterations in the fine root morphology, leading to promoting the accumulation of biomass in grown G. uralensis when subjected to P-deficient conditions. Furthermore, it was observed that the nutrient uptake of G. uralensis was significantly improved when subjected to P-deficient conditions but treated with LaCl3. Additionally, the yield and quality of the medicinal organs of G. uralensis were significantly enhanced.

Effect of Metal Chloride Impurities on Equilibrium Potential of Fe/FeCl2 in Eutectic LiCl-KCl

Abstract In this study, interaction of dilute metal chloride solutes in molten eutectic LiCl-KCl was studied via equilibrium potential measurements. Open circuit potential (OCP) was measured between a pure iron rod and a Ag/AgCl reference electrode with concentration of FeCl2 varying from 0.2-1 mol% at 530oC. The Nernst equation was used to calculate activity coefficient of FeCl2 based on OCP. Measurements were made in LiCl-KCl-FeCl2 with and without additions of 0.5 mol% CsCl, NaCl, and LaCl3. The activity coefficient of FeCl2 was found to be unaffected by these small concentrations of CsCl, LaCl3, and NaCl. However, there was observed evidence that the activity coefficient of FeCl2, above 0.8 mol% Fe, may be affected by the presence of LaCl3 at higher concentrations beginning around 0.5 mol% La. Over the full range of conditions tested, the activity coefficient of FeCl2 in molten LiCl-KCl ranged from 2.95x10-5 to 1.01x10-4.

Characterization of friction and wear of phenolic resin matrix composites reinforced by bamboo fibers of alkaline and LaCl3 treatment

Mechanical and tribological properties of phenolic resin matrix composites reinforced by bamboo fibers, which were pre-treated with sodium hydroxide (NaOH) and post-treated with lanthanum chloride (LaCl3), were characterized by hardness, impact, microscratch tests, friction and wear testers, and thermogravimetric analysis. Bamboo fibers before and after modification were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). Hemicellulose and lignin of bamboo fibers can be dissolved by alkaline or NaOH treatment, resulting in a rough surface. The high coordination number of rare earth atoms in LaCl3 solution enhanced the formation of chemical bonds between the hydroxyl groups of bamboo fibers and the oxygen-containing groups on the molecular chain of phenolic resin. The hardness and impact strength of the composites both firstly increased and then decreased with an increase in LaCl3 concentration or soaking duration in LaCl3 solution. Tribological performance (e.g. high-temperature friction coefficient, wear rate, thermogravimetric loss, crack propagation) of phenolic resin matrix composites was significantly improved by the treated bamboo fibers. The optimum mechanical and tribological properties of bamboo fiber-reinforced phenolic resin matrix composites were achieved under the conditions of LaCl3 concentration of 10% and soaking duration of 30 min.

Determination and Comparison of Parameters from Cyclic Voltammetry of LaCl3 in Eutectic LiCl-KCl

Electrochemical measurements of LaCl3 were obtained in eutectic LiCl-KCl at 773 K. Cyclic voltammetry data were acquired using a tungsten electrode LaCl3 amounts in the molten salt in the range of 0.5 to 3.0 wt%. Both cyclic voltammetry and Tafel analyses of the data resulted in calculation of values for the charge transfer coefficient (0.262), diffusion coefficient (1.67 × 10-5 cm2 s-1), exchange current density (0.0148 to 0.0473 A cm-2), and charge transfer resistance (0.404 to 1.99 Ω) related to lanthanum ions in the molten salt. Calculated values were compared to those available in the literature. The values of parameters found in literature varied significantly in comparison to those in the present study due to dissimilar experimental conditions, e.g., electrode material, temperature, and LaCl3 concentration.

Action of the Nrf2/ARE signaling pathway on oxidative stress in choroid plexus epithelial cells following lanthanum chloride treatment

Lanthanum (La) can damage the blood brain barrier when it enters the brain tissue, causing learning and memory dysfunction. Currently, few studies have focused on La-induced oxidative stress in choroid plexus epithelial cells, which can severely impair the normal function of the blood-cerebrospinal fluid barrier (BCSFB) and ultimately cause central nervous system dysfunction. The nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant response element(ARE) signaling pathway is one of the major antioxidant systems and is vital in protecting cells against oxidative injury in rodents. In this study, Z310 cells were employed to construct BCSFB in vitro and treated with lanthanum chloride (LaCl3); meanwhile, 40 μmol/L tert-butylhydroquinone and the corresponding concentration of LaCl3 was used as the intervention groups. The results showed that LaCl3 treatment markedly decreased Z310 cell viability, increased the necrosis rate, and then reduced the transepithelial electrical resistance value of BCSFB in vitro; reactive oxygen species levels gradually increased, catalase and glutathione peroxidase activities decreased; furthermore, Nrf2 was significantly downregulated, and the expression of Nrf2 downstream genes such as heme oxygenase1, NADP(H): dehydrogenase quinone1, glutathione thiotransferase etc. noticeably decreased; in addition, interleukin-1β and tumour necrosis factor-α associated with Nrf2 activation noticeably increased. However, tert-butylhydroquinone could activate the Nrf2/AER signaling pathway and attenuate the Z310 cell oxidative damage induced by LaCl3. Thus, the Nrf2/ARE signaling pathway is probably involved in weakening the BCSFB in vitro that is created by La-induced oxidative stress. Tert-butylhydroquinone can activate this pathway to reverse severe oxidative damage, which significantly strengthen the function of BCSFB.

La3+ modified poly(γ‐glutamic acid) hydrogels with high strength and anti‐swelling property for cartilage regeneration

AbstractThe applications of synthetic hydrogels in cartilage regeneration are usually limited by their weak mechanical properties, uncontrolled swelling/degradation, and insufficient osteogenic activity. Developing tough hydrogels have been attracting great attention in biomedical engineering. In this study, a high strength and tough poly(γ‐glutamic acid) (γ‐PGA) hydrogels with excellent anti‐swelling property were developed by immersing as‐prepared γ‐PGA hydrogels in LaCl3 aqueous solution. Results revealed that the concentration of LaCl3 aqueous solution has great influence on the mechanical properties of γ‐PGA hydrogels. The tensile strength of γ‐PGA hydrogels improved from 0.12 ± 0.02 MPa to 14.65 ± 0.48 MPa when LaCl3 concentration was 0.15 M. Moreover, the swelling ratio decreased from 1035.75 ± 33.16% to 18.21 ± 3.08%. The morphology and microstructure of La3+ reinforced γ‐PGA hydrogels were characterized by SEM/EDS, FT‐IR and XPS. Furthermore, in vitro cytocompatibility of La3+ reinforced γ‐PGA hydrogels was evaluated via MC3T3‐E1 cells. Finally, this study provides a facile and effective strategy for modifying the mechanical and swelling properties of γ‐PGA‐based hydrogels, which offers great potential applications in cartilage repair and regeneration.

Effect of carbon nanotubes modified with different concentrations of rare earth lanthanum on the mechanical and tribological properties of epoxy composites

Rare earth modified acidified carbon nanotubes were prepared by functionalization of acidified carbon nanotubes with different concentrations of LaCl3. The modification results were characterized by Fourier-transform infrared and X-ray photoelectron spectroscopy. The rare earth successfully increases the surface activity of the acidified carbon nanotubes. Polymer matrix composites were prepared by using the rare earth modified acidified carbon nanotubes as the reinforcement in epoxy matrix. Mechanical properties were analyzed by Zwick Z100 testing machine and the tribological behaviors were test by multifunctional tribological tester. Compared with pure epoxy (epoxy resin), the mechanical strength of the best composite sample was increased by 50–120%, the coefficient of friction was reduced by 19.4% and the wear rate was reduced by approximately 40 times. The experimental results show that the RE concentration of 0.2–0.3 wt% has the most obvious influence on the properties of polymer composites. The mechanism of rare earth reinforcement in polymer matrix is analyzed and suggested.

Lanthanum chloride enhances the photosynthetic characteristics and increases konjac glucomannan contents in Amorphophallus sinensis Belval

Lanthanum (La) has been used as agricultural inputs in order to enhance yield and improve crop quality. However, little is known about the effect of La on the photosynthesis and growth of Amorphophallus sinensis, a worldwide food source. The effects of La on the photosynthetic and chlorophyll fluorescence parameters, photosynthetic pigments, corm yield, and konjac glucomannan (KGM) of Amorphophallus sinensis were investigated via field experiments. The leaves were sprayed with different concentrations of LaCl3 (20, 80, 160, and 240 mg L-1). The results exhibited an increasing effect of LaCl3 on photosynthetic rate, stomatal conductance, intercellular CO2 concentration, chlorophyll fluorescence parameters, photosynthetic pigments, corm yield, and KGM, when concentration was between 20 and 240 mg L-1, and the most effective concentration was 160 mg L-1. Therefore, moderate LaCl3 concentration may increase yield of Amorphophallus sinensis by enhancing the photosynthetic efficiency, increasing the corm yield, and KGM contents.

Charge reversal of sulfate latex particles in the presence of lanthanum ion

Effects of multivalent cations and its hydrolyzed forms on the charge reversal are investigated by measuring electrophoretic mobilities of three different sulfate latex particles bearing pH-independent surface charge densities as a function of LaCl3 concentration and pH. The obtained experimental results are analyzed by using a simple adsorption model including an ion-ion correlation model, intrinsic energy of adsorption for hydrolyzed La ions, and the speciation calculation of La. From the experimental electrophoretic mobilities at pH = 4 without hydrolyzed La ions, we observed that the LaCl3 concentrations at charge reversal increased with decreasing the magnitude of the latex charge density. This experimental trend can be qualitatively captured by the ionic correlation model used here. While the sulfate latex particles bear pH-independent surface charge and the LaCl3 concentration was lower than the concentration where the charge reversal took place at pH 4, the increase in pH significantly gave rise to the charge reversal at pH above 7.8 where the hydrolyzed La ions begin to form. Therefore, this charge reversal at higher pH can be assigned to the stronger adsorption of hydrolyzed La ions. In addition, we demonstrate that the simple model can capture such experimental trends of charge reversal by introducing surmised values of its intrinsic energy of adsorption. Therefore, our results confirm that the ion correlation can be a prevailing mechanism on the charge reversal at low pH, while the stronger adsorption of hydrolyzed La ions predominates to induce the reversal with increasing pH.

Lanthanum chloride improves maize grain yield by promoting photosynthetic characteristics, antioxidants enzymes and endogenous hormone at reproductive stages

Despite an increase in application spectrum of rare earth elements in agriculture, all studies show that the suitable accumulation of rare earth elements can improve the crop seedling growth, but there is little research about REEs on physiological mechanisms of crops at reproductive stages. Therefore, this study was conducted to examine the possible potential benefits of lanthanum chloride (LaCl3) on the senescence and grain yield responses of maize. In this study, maize seeds were pre-treated by soaking with LaCl3 at the concentrations of 0 (CK), 400 (LC1), 800 (LC2) and 1200 (LC3) μmol/L, to evaluate its effect on the green leaf area, chlorophyll contents, photosynthesis, antioxidants, endogenous hormones in the later crop growth stages. The results show that LC1 and LC2 treatments evidently increase green leaf area, above ground dry biomass, accompanied by a distinct increase in the chlorophyll contents, and photosynthetic capacity, which promote the ear characteristics and grain yield of maize. In addition, LC1 and LC2 treatments simultaneously increase the activities of antioxidants, including superoxide dismutases, catalases, peroxidases, soluble protein, and enhanced levels of auxin, gibberellin and zeatin, following a dose-response tendency. Themalondialdehyde and abscisic acid levels transiently increase with the progression in the growth stage of the crop but are markedly decreased at LC1 and LC2 treatments, while LC3 treatment has no significant effect on malondialdehyde and even accelerates the accumulation of abscisic acid in maize leaves. Our data suggest that seed priming with LaCl3 at a suitable concentration range (400–800 μmol/L) can prolong the functional periods of leaves, increase photosynthetic capacity, enhance antioxidant activity, and alter endogenous hormone levels at reproductive stages, resulting in delaying leaf senescence rate and increasing yield. However, the moderate concentration of LaCl3 for maize is LC2 (800 μmol/L), and can be effectively used to improve grain yield of maize.

Lanthanum-containing bioparticles are associated with the influence of lanthanum on high phosphate mediated bone marrow stromal cells viability.

Lanthanum (La)-based binder appears effective in reducing serum inorganic phosphate (Pi) levels among chronic dialysis patients, yet concern remains about La accumulation in bone during long-term oral administration. In this study, the effect of lanthanum chloride (LaCl3) on bone marrow stromal cells (BMSCs) viability was investigated under high Pi situation. We found low concentration (10-9M) of LaCl3 increased BMSCs viability, while high concentration (10-5M) of LaCl3 not only inhibited BMSCs viability but also stimulated high Pi induced cell apoptosis. In addition, La-containing calcium phosphate (CaP) particles can be detected on cell surfaces and inside cells. We also found that inhibition of CaP formation by adding sodium pyrophosphate, a recognized inhibitor of hydroxyapatite formation, abrogated LaCl3 induced the BMSCs viability. For isolated La-containing CaP particles, the particle size increased and crystal phase switched with elevated concentration of LaCl3. These results demonstrated that La-containing CaP particles were associated with the process of LaCl3 mediated BMSCs viability and the physicochemical properties of these particles played an important role in modulating BMSCs function.

Investigation on the influence of LaCl3 concentration on the electrical conduction mechanism of chemical-bath deposited LaF3/porous-silicon structure

AbstractEffect of LaCl3 concentration on the electrical conduction mechanism of LaF3/porous silicon (PS) structure has been investigated in this work. LaF3 layers have been deposited by a novel chemical bath deposition (CBD) technique. With this simple technique, LaF3 produced as LaCl3 are made to react with hydrofluoric (HF) acid on the porous silicon substrate. This enables direct deposition of LaF3 on the pore walls of the porous silicon leading to a successful passivation of PS. The compositions of the deposited LaF3 were confirmed by Energy Dispersive of X-ray (EDX) analysis. The electrical conduction study has been done by impedance analyzer (HP4294A). From this study it can be concluded that the conductance increases with LaCl3 concentration but decreases for higher concentration.

Determination of activity coefficient of lanthanum chloride in molten LiCl-KCl eutectic salt as a function of cesium chloride and lanthanum chloride concentrations using electromotive force measurements

The thermodynamic behavior of lanthanides in molten salt systems is of significant scientific interest for the spent fuel reprocessing of Generation IV reactors. In this study, the apparent standard reduction potential (apparent potential) and activity coefficient of LaCl3 were determined in a molten salt solution of eutectic LiCl-KCl as a function of concentration of LaCl3. The effect of adding up to 1.40 mol % CsCl was also investigated. These properties were determined by measuring the open circuit potential of the La—La(III) redox couple in a high temperature molten salt electrochemical cell. Both the apparent potential and activity coefficient exhibited a strong dependence on concentration. A low concentration (0.69 mol %) of CsCl had no significant effect on the measured properties, while a higher concentration (1.40 mol %) of CsCl caused an increase (become more positive) in the apparent potential and activity coefficient at the higher range of LaCl3 concentrations.

Voltammetric Analysis of Mixtures of Molten Eutectic LiCl-KCl Containing LaCl3 and ThCl4 for Concentration and Diffusion Coefficient Measurement

Several electrochemical techniques, including cyclic voltammetry (CV), chronopotentiometry-open circuit potential (CP-OCP), chronoamperometry (CA) and normal pulse voltammetry (NPV) were applied to the eutectic LiCl-KCl melt containing LaCl3 and ThCl4 at 773K. The dependence of diffusion coefficient of La(III) on concentration of LaCl3 was investigated by using CV, CP and CA. As the concentration of LaCl3 increases, the DLa(III) value obtained from CV gradually decreases, while the values derived from CA and CP exhibit a dome-shaped variation trend. In the LiCl-KCl-LaCl3-ThCl4 system, the diffusion coefficients of La(III) and Th(IV) are both approximately constant regardless of changes in the composition of LaCl3 and ThCl4. Concentration correlations were developed for LaCl3 and ThCl4 using the normalized CV peak heights in addition to the diffusion-limited relationships for CV, CA and NPV. NPV was found to be superior for the concentration prediction over the range studied in this work.

Dependency of built-in potential of LaF3/porous-silicon heterostructure prepared by chemical bath deposition technique on the concentration of LaCl3 and annealing temperature

Effect of LaCl3 concentration and annealing temperature on the built-in potential of LaF3/PS heterojunction has been investigated in this report. LaF3 layers have been deposited by a novel chemical bath deposition (CBD) technique. With this simple technique LaF3 produced as LaCl3 are made to react with hydrofluoric acid on the porous silicon (PS) substrate. This enables direct deposition of LaF3 on the pore walls of the PS leading to a successful passivation of PS. The compositions of the deposited LaF3 were confirmed by energy dispersive of X-ray analysis. The built-in potential decreases with LaCl3 concentration and increases with annealing temperature. Therefore, by changing the LaCl3 concentration and annealing temperature quality of the LaF3 layer on PS can be optimized. From the experimental results it can be concluded that lanthanum fluorides can be deposited on the PS surface by the CBD technique, which provides the required passivation for PS. This passivation can enable the PS to be considered as an important material for photonics.

Influence of LaCl3 concentration and annealing temperature on the diode ideality factor of LaF3/porous-silicon structure prepared by chemical bath deposition technique

Effect of LaCl3 concentration and annealing temperature on the diode ideality factor of LaF3/PS heterojunction has been investigated in this report. LaF3 layers have been deposited by a novel chemical bath deposition (CBD) technique. With this simple technique LaF3 produced as LaCl3 are made to react with hydrofluoric acid on the porous silicon (PS) substrate. This enables direct deposition of LaF3 on the pore walls of the PS leading to a successful passivation of PS. The compositions of the deposited LaF3 were confirmed by energy dispersive of X-ray analysis. The diode ideality factor increases with LaCl3 concentration and decreases with annealing temperature. Therefore, by changing the LaCl3 concentration and annealing temperature quality of the LaF3 layer on PS can be optimized. It was also seen that the Ag/LaF3/PS/Si/Ag structure showed the formation of Schottky diode with a threshold voltage of about 5.5 V. From the experimental results it can be concluded that lanthanum fluorides can be deposited into the pores as well as on the top of PS by the CBD technique, which provides the required passivation for PS. This passivation can enable the PS to be considered as an important material for photonics.

Experimental observation of the ion-ion correlation effects on charge inversion and strong adhesion between mica surfaces in aqueous electrolyte solutions.

Direct force measurements between two mica surfaces in aqueous electrolyte solutions over broad ranges of LaCl3 concentrations and pH values were carried out with a surface forces apparatus. Charge inversion on mica surfaces is detected once the LaCl3 concentration reaches a critical value. With the continual increase of LaCl3 concentrations, the mica surface will be overscreened by the counterions. It is demonstrated that the two mica surfaces may experience the jump-in contact even at high LaCl3 concentrations, which is seldom seen in monovalent salt solutions. The strong adhesion cannot be attributed to the van der Waals force alone, but should include the ion-ion correlation forces. Through adjusting the pH values in LaCl3 solutions, the ion-ion correlation force can be evaluated quantitatively. These results provide important insight into the fundamental understanding in the role of ion-ion correlations in ion screening mechanism and interactions between charged objects.

Wear particle-mediated expressions of pro-inflammatory cytokines, NF-κB and RANK were impacted by lanthanum chloride in RAW264.7 cells

To explore the impact of different concentrations of lanthanum chloride (LaCl3) on critical components of wear particle-mediated signaling pathways in inflammation and osteoclastogenesis, RAW264.7 cells were naturally divided into eight groups and analyzed by CCK-8 assay, flow cytometry, ELISA, RT-PCR and western blot after treatments. The results showed that three concentrations of LaCl3 had no influence on viability of RAW264.7 cells and down-regulated receptor activator of nuclear factor κB (RANK) instead of macrophage colony-stimulating factor receptor (M-CSFR). Additionally, 2.5 and 10 μmol/L LaCl3 could significantly inhibit gene and protein levels of pro-inflammatory cytokines (tumor necrosis factor-α and interleukin-1β, i.e., TNF-α and IL-1β and NF-κB/p65, but 100 μmol/L LaCl3 did not exert an obvious inflammation-inhibiting effect, and even induced inflammation. In conclusion, these findings demonstrated that LaCl3 was able to suppress wear particle-induced inflammation and activation of NF-κB in a certain range of concentrations in vitro and mainly decrease the expression of RANK, but not M-CSFR, all of which were generally recognized to play a pivotal role in osteoclastogenesis.

La3+-Induced Asymmetric Current Inhibition in OmpF Channel

OmpF is a general diffusion porin located at the outer membrane of Escherichia coli. Its aqueous pore has an hour-glass shape with a narrow constriction placed at about half of the channel pathway. Two acidic residues in this region face a cluster of three positive arginines, creating a high transverse electric field. This separates the permeation trajectories of cations and anions, resulting in a particularly effective permeation.We previously reported that millimolar concentrations of LaCl3 added to a symmetric KCl solution also yield a current reduction in OmpF channel [1]. Here we use planar bilayer electrophysiology to understand several characteristic features of the partial channel blocking induced by lanthanum ion: 1) La3+ cations reduce the current only when they are added at one side of the membrane (the side of protein addition); 2) The reduction in channel conductance only appears for positive applied potentials; 3) The current inhibition is significantly dependent on the concentration of the supporting electrolyte, KCl; 4) These three effects become apparent with tiny quantities of La3+ ions.We demonstrate that a competitive interaction between La3+ and K+ ions is compatible with the asymmetric inhibition. In addition, we analyze the voltage dependence of the current reduction to obtain information about the asymmetry of the blocking. Finally, we show that the substitution of several residues located at the OmpF central constriction can either enhance or inhibit the lanthanum block, pointing out that the interaction between La3+ ions and the OmpF channel is likely to occur in the vicinity of the mutated residues.[1] C. Verdia-Baguena, et al. (2012) J. Phys. Chem. C 116, 6537−6542