Gadolinium Nitrate Solution Research Articles

Structure, morphology and functional characteristics of Gd2Ti2O7 nanocrystals formed under various annealing conditions

This article is devoted to the study of the processes of formation and growth of nanocrystals with the pyrochlore structure in the TiO2-Gd2O3 system. A mixture of an aqueous solution of gadolinium nitrate and a solution of titanium isopropoxide with polyethylene glycol in isopropyl alcohol was evaporated to a gel state, and then it was heat-treated using a one- or two-stage scheme. The study showed that the material being formed has a trabecular structure with a developed system of macropores. The use of the two-stage roasting method allows a uniform distribution of titanium and gadolinium atoms in the sample. Gadolinium titanate with a pyrochlore structure, which is formed using an aggregation mechanism at a temperature T = 700 °C from an X-ray amorphous precursor, is a variable composition compound. It has been shown that in terms of obtaining a monophasic product, the possibility of varying the size of nanocrystals, and defects in the pyrochlore structure, the most promising heat treatment mode is synthesis in the temperature range of 750–900 °C. In this case, the possibility of controlling the above characteristics of Gd2Ti2O7 nanoparticles can be implemented by varying the ratio of titanium- and gadolinium-containing precursors in the initial mixture, the duration of the isothermal exposure process.

Bio-inspired gadolinium coated titania nanotubes for orthopaedics

The distinguished corrosion behaviour along with the high strength-to-density ratio makes titanium (Ti) and its alloys an unavoidable material for long-term orthopaedic implant application. Though titanium was used as an implant material for many years in the clinical trial, the osseointegration of titanium implants with the bone around them is minimal leading to implant failure. For this study, combinational treatment of Cp-Ti by anodization using phosphate and fluoride electrolyte to form titania nanotubes (TNT) followed by dip coating with gadolinium nitrate solution. The corrosion behaviour of gadolinium-coated TNT (Gd-TNT) showed better corrosion resistance than TNT. The surface reactivity of the samples were analysed using a scanning electrochemical microscope (SECM). SECM is one of the powerful techniques to determine the surface chemical reactivity of metallic biomaterials in simulated body fluids. X-ray diffraction (XRD) analysis showed the anatase phase of titania nanotube formation. Attenuated Total Reflection Fourier Transform Infrared spectroscopy (ATR-FT-IR) was used to analyse the functional groups of the sample surface. The walls of the TNT were covered with gadolinium oxide which was confirmed by X-ray photoelectron spectroscopy (XPS) studies. Also, the mineralization of Gd-TNT was initiated after 24 h of immersion in simulated body fluid (SBF). The cytocompatibility studies indicated that the cell viability percentage of Gd-TNT was 69 % higher than the bare. In short, Gd-TNT can be used for treating the bone-related disorder.

Biofunctionalization of Mg implants with gadolinium coating for bone regeneration

Magnesium (Mg) alloys are biodegradable and biocompatible in nature, hence used as bio-implants. Mg alloys possess favourable mechanical properties same as that of human bone. In this work, we demonstrate a simple strategy of formulating a gadolinium conversion coating (GCC) on a biodegradable AZ31 Mg implant that effectively diminishes the corrosion rate and enhances bone formation. AZ31 Mg alloys were immersed in gadolinium nitrate solution at different durations (5, 15, 30, 45 and 60 min) and labeled as GCC-5, GCC-15, GCC-30, GCC-45 and GCC-60 to fabricated gadolinium conversion coating (GCC) on AZ31 Mg alloys. The rapid degradation of AZ31 Mg alloy was reduced by GCC. The surface morphological analysis with the Scanning Electron Microscope (SEM) showed that the vertically arranged cross-linked nanolamellar plates were grown on the AZ31 Mg alloy surface. Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) results evident that the GCC consists of magnesium oxide and gadolinium oxide were present in the crystalline state. The in-vitro biomineralization of the GCC was analyzed by immersing in simulated body fluid (SBF) solution for 7 days and confirms the formation of nanoglobular hydroxyapatite. The cell culture studies showed an increase in the cell numbers than the bare.

Synthesis of Gadolinium Complexes Using Medicinal Plant Extracts

Background: Gadolinium compounds are used as contrast enhancers in MRI imaging. Generally, free metal ions are not used in MRI imaging due to their toxicity. To reduce the toxicity of the free form of the metal, complexing agents are employed for making nanoparticles. Due to their low toxicity and natural abundance, plant extracts having potential to function as chelating agents are good alternatives for the formation of gadolinium nanoparticles. Methods: Aqueous extracts of five plant species, including Thymus daenensis Celak, Nepeta sessilifolia Bung, Crocus sativus L., Salvia hydrangea DC. ex Benth, and Hymenocrater incanus Bunge were prepared. Five complexes were produced as the result of each extract’s reaction with gadolinium nitrate solution in the presence of 1 mM solution of NaOH. The obtained complexes were analyzed adopting the Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and Energy dispersive x-ray analysis (EDAX) techniques. Results: EDAX analysis of the obtained complexes confirmed the presence of gadolinium in all complexes. Among the five complexes, the highest percentage of gadolinium (21.07) was recorded for the complex derived from the extract of H. incanus Bunge, while the lowest one (9.33) was detected for the complex derived from the T. daenensis Celak. Despite adopting various methods to disperse the complex particles in deionized water in order for determining the particle size, the high adhesion of the particles prevented the determination of the desired particle size in nanoscale. Conclusion: Although synthesizing the complexes was successful and EDAX confirmed the presence of gadolinium metal in them, SEM analysis failed to prove their nanoparticle structure. The high tendency of solid particles to adhere was found to prevent the formation of independent nanoparticles in solution.

Crown Ether-Immobilized Cellulose Acetate Membranes for the Retention of Gd (III).

This study presents a new, revolutionary, and easy method of separating Gd (III). For this purpose, a cellulose acetate membrane surface was modified in three steps, as follows: firstly, with aminopropyl triethoxysylene; then with glutaraldehyde; and at the end, by immobilization of crown ethers. The obtained membranes were characterized by Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS), through which the synthesis of membranes with Gd (III) separation properties is demonstrated. In addition, for the Gd (III) separating process, a gadolinium nitrate solution, with applications of moderator poison in nuclear reactors, was used. The membranes retention performance has been demonstrated by inductively coupled plasma mass spectrometry (ICP-MS), showing a separation efficiency of up to 91%, compared with the initial feed solution.

Formation of Gd2O3:Nd3+ nanocrystals in silica microcapillary preforms and hollow-core anti-resonant optical fibers

A silica microcapillary preform and a hollow-core anti-resonant optical fiber doped with small-size (<50 nm) Gd2O3:Nd3+ nanocrystals are fabricated by the liquid polymer-salt method for the first time, to our knowledge. Aqueous solutions of gadolinium nitrate and neodymium chloride and a soluble organic polymer (polyvinylpyrrolidone) are used to form Gd2O3:Nd3+ nanocrystals inside the air channels of a preform followed by drawing of an optical fiber. Characterization of microcapillary preforms and optical fibers doped with Gd2O3:Nd3+ nanocrystals is performed with XRD, SEM, optical microscopy and photoluminescence analysis. Basic technological factors affecting structural and luminescent properties of the fabricated materials are considered. Particularly, it is found out that microcapillary preforms and hollow-core anti-resonant optical fibers doped with Gd2O3:Nd3+ nanocrystals demonstrate photoluminescence (emission spectra and luminescence lifetimes) characteristic to Nd3+ ions in metal sesquioxides. In addition, it is revealed that luminescence kinetics in optical fibers is described by two exponential dependences with decay times τ1 = 12 µs and τ2 = 233 µs that can be attributed to the feature of a cubic crystal structure of Gd2O3.

Synthesis and Characterization of Cellulose Acetate Membranes with Self-Indicating Properties by Changing the Membrane Surface Color for Separation of Gd(III)

This study presents a new, revolutionary, and easy method for evaluating the separation process through a membrane that is based on changing the color of the membrane surface during the separation process. For this purpose, a cellulose acetate membrane surface was modified in several steps: initially with amino propyl triethoxysilane, followed by glutaraldehyde reaction and calmagite immobilization. Calmagite was chosen for its dual role as a molecule that will complex and retain Gd(III) and also as an indicator for Gd(III). At the contact with the membrane surface, calmagite will actively complex and retain Gd(III), and it will change the color of the membrane surface during the complexation process, showing that the separation occurred. The synthesized materials were characterized by Fourier transform infrared spectroscopy (FT-IR), thermal analysis (TGA-DTA), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy, demonstrating the synthesis of membrane material with self-indicating properties. In addition, in the separation of the Gd(III) process, in which a solution of gadolinium nitrate was used as a source and as a moderator in nuclear reactors, the membrane changed its color from blue to pink. The membrane performances were tested by Induced Coupled Plasma–Mass Spectrometry (ICP-MS) analyses showing a separation process efficiency of 86% relative to the initial feed solution.

Operating experience feedback from incidental fluctuations of the power measurement channel at ETRR-2

Abstract This paper provides analysis of the operating experience feedback from two events of incidental fluctuations of the power measurement channels at Egypt Second Research Reactor (ETRR-2). In the first event, the fluctuation was due to improper functioning of the secondary cooling system, while in the second one the fluctuation was associated with a leakage of a gadolinium nitrate solution into chambers surrounding the reactor core (which are part of a diverse second shutdown system of the reactor). The paper describes these events, including observation of the reactor operation performance and operators’ actions, and provides the root causes analysis of these events along with the corrective actions. Lessons learned from these events, which are generically applicable to other research reactors, are also identified and presented. The analysis showed the vital role of continuing training of reactor operators, consideration of human factors in all activities during the reactor lifetime, and quality checks and field verifications during operation and post-maintenance works to the safety and availability of research reactors. The analysis also showed that underperformance of non-safety components could have an effect on those important to safety and could negatively impact the availability and the operational performance of the reactor.

Synthesis of Nanosized Gadolinium Oxide

A method of obtaining nanoparticles of gadolinium oxide by the sol-gel method from a gadolinium nitrate solution is considered. The conditions of gadolinium oxide precipitation and the size of colloidal particles are determined. Using differential scanning calorimetry (DSC), the phase transitions of gadolinium hydroxide gel on cooling to a negative temperature followed by heating from –30 to 250°C and mass loss (88.4%) in the gel during the heating to 250°C are established. The dependence of the degree of conversion in the dehydration process on the temperature is found and the activation energy of this process is calculated (54.03 kJ/mol). The particle size after the gel calcination (8–16 nm) is estimated using the TEM method.

Three-dimensional numerical computation of gas-liquid two-phase flow under pseudo microgravity environment using a superconducting electromagnet

By using the strong magnetic field generated by a superconducting electromagnet, theoretically it is possible to produce the pseudo microgravity environment on the ground. The final goal of this research is to obtain knowledge of fluid control under a strong magnetic field using a superconducting electromagnet. In this study, in order to examine a method for accurate CFD computation, we carried out computation for a gas-liquid two-phase flow under a strong magnetic field. A milk crown phenomenon inside the bore of superconducting electromagnet is studied. The liquid is assumed to be an aqueous gadolinium nitrate solution (15%). The CLSVOF method is used for the computation of the two-phase flow and the HSMAC method is used for the pressure correction. We evaluate how much the interior of the superconducting electromagnet is in a pseudo microgravity environment by using the equation expressing the gravity level. In addition, in order to speed up the calculation, GPU parallel computation is performed, realizing about 22 times faster than CPU single computation. As a result, we succeeded in investigating a method for computation a gas-liquid two-phase flow in a strong magnetic field.

Visualization and analysis of magnetothermal convection of paramagnetic liquid in the Rayleigh-Benard model

We examined the heat transfer of magnetothermal convection in a Rayleigh-Benard model (height 9.2 mm, vessel diameter 20 mm, aspect ratio 2.17). The working fluid was an aqueous gadolinium nitrate solution of 0.15 mol/kg ($\mathrm{pH}=4.52$ at 305.5 K, paramagnetic substance). Not only the magnetic body force but also the temperature dependence of paramagnetic susceptibility according to Curie's law provides the driving body force of convection and exerts a decisive influence over the heat transfer performance. The visual observation of the isothermal contour of convection was realized by the addition of a thermochromic liquid crystal (TLC). Using a large upward magnetic body force, i.e., $(\stackrel{P\vec}{b}\ifmmode\cdot\else\textperiodcentered\fi{}\stackrel{P\vec}{\ensuremath{\nabla}})\phantom{\rule{0.16em}{0ex}}{b}_{z}=83.31\phantom{\rule{0.16em}{0ex}}{\mathrm{T}}^{2}/\mathrm{m}$ at the vessel center, we succeeded in visualizing the horizontal isothermal illuminant of the TLC, which revealed the realization of a quasiweightless condition in the Rayleigh-Benard model. The heat transfer on convection was analyzed by the method of Churchill and Ozoe. Its performance was enhanced by the downward magnetic body force and was suppressed by the upward magnetic body force, as compared with Rayleigh-Benard convection. The convective flows in the experiment ($\mathrm{Prandtl}\phantom{\rule{0.16em}{0ex}}\mathrm{number}=5.17$, $\mathrm{Ra}=1.53\ifmmode\times\else\texttimes\fi{}1{0}^{5}$, aspect ratio 2.0) were numerically simulated by three-dimensional computation. All the experimental and numerical results were arranged by Rayleigh number (Ra) and Nusselt number (Nu). In addition, we introduced the magnetic Rayleigh number (${\mathrm{Ra}}_{\mathrm{m}}$) instead of Ra. The results of Nu plotted versus the ${\mathrm{Ra}}_{\mathrm{m}}$ were closely distributed in the vicinity of the Silveston curve. This relationship reveals that the heat transfer on magnetothermal convection is controlled by the use of ${\mathrm{Ra}}_{\mathrm{m}}$.

Effect of Gd infiltration on NiO-CeO 2 anode substrates for intermediate-temperature solid oxide fuel cells

Abstract In this study, solid oxide fuel cells (SOFCs) were fabricated using cerium oxide in the anode support layer (ASL) instead of gadolinium-doped ceria (GDC). To compensate for the deficiency in ionic conductivity and catalytic activity of CeO2, a gadolinium nitrate solution was infiltrated in the ASL before sintering at 1450 °C. The ohmic and polarization resistance of the cell were reduced upon Gd-nitrate infiltration, which also increased the sinterability of the ASL. However, excessive infiltration was found to degrade the electrochemical properties of the cell. Therefore, the conditions for infiltration were optimized in this study. The peak power density of the cell after Gd-nitrate infiltration was 0.662 W, 68% higher than that of the reference cell without Gd-nitrate infiltration.

Poison injection in AHWR calandria: Flow pattern and mixing characteristics

In Advanced Heavy Water Reactor (AHWR), two active, independent, functionally diverse, fast acting shut down systems are used. Shut Down System-1 (SDS-1) consists of mechanical shut off rods and Shut Down System-2 (SDS-2) based on liquid poison injection into the moderator. Gadolinium nitrate solution, which acts as neutronic poison, is injected in heavy water moderator through a set of nozzles located inside calandria vessel. This poison injection into moderator inside calandria is expected to take place in a very short time to shut down the reactor. As SDS-2 is critical for the safety of plant, detailed knowledge of poison distribution in calandria is required.CFD analysis using OpenFOAM has been carried out for high pressure poison injection of Shut Down System-2 of AHWR for various design options. Validation of CFD model is performed by experimental measurements. Experiments are performed for impulsively started poison jet in a 1/3.3 scaled and full-scale experimental facilities with array of tubes. In particular, the growth of poison jet is measured experimentally and CFD simulations are performed. An excellent agreement is found between CFD simulations and experimental data. CFD simulation shows that the poison covers a major portion of active core in 2s time. In addition to this, effect of moderator flow and heat generation in moderator on poison distribution has also been studied.

Magnetic Resonance Study of Gadolinium-Grafted Nanodiamonds

We report on EPR and 13C and 1H NMR studies of detonation nanodiamond particles with surface grafted by paramagnetic gadolinium ions obtained by ion exchange with hydrogen atoms of carboxyl groups through the reaction of aqueous nanodiamond suspension with an aqueous solution of gadolinium nitrate. Our findings give clear evidence that Gd3+ ions are chemically bound to the nanodiamond surface and interact with electron and nuclear spins of the diamond nanoparticle, which results in acceleration of electron and nuclear spin–lattice relaxations. A model of positioning of Gd3+ ions on the DND surface terminated by oxygen-containing groups is suggested. The distance between the Gd ion and nanodiamond surface is estimated by relaxation measurements as 0.32 nm. Biomedical applications of the studied nanomaterials are discussed.

Magnetic studies of a detonation nanodiamond with the surface modified by gadolinium ions

The diamond nanoparticle surface is modified with Gd(III) ions by ion exchange with carboxyl group protons during the reaction of nanodiamond hydrosol with an aqueous solution of gadolinium nitrate. The results of the study by electron paramagnetic resonance and static magnetization measurements at low temperatures confirm the attachment of gadolinium ions to the surface of the diamond particle ∼5 nm in size. A spatial model of the arrangement of ions, in which the ion is located away from the surface by no more than 0.4 nm, is proposed.

Neutron imaging of ion transport in mesoporous carbon materials

Neutron imaging is presented as a tool for quantifying the diffusion of ions inside porous materials, such as carbon electrodes used in the desalination process via capacitive deionization and in electrochemical energy-storage devices. Monolithic mesoporous carbon electrodes of ∼10 nm pore size were synthesized based on a soft-template method. The electrodes were used with an aqueous solution of gadolinium nitrate in an electrochemical flow-through cell designed for neutron imaging studies. Sequences of neutron images were obtained under various conditions of applied potential between the electrodes. The images revealed information on the direction and magnitude of ion transport within the electrodes. From the time-dependent concentration profiles inside the electrodes, the average value of the effective diffusion coefficient for gadolinium ions was estimated to be 2.09 ± 0.17 × 10(-11) m(2) s(-1) at 0 V and 1.42 ± 0.06 × 10(-10) m(2) s(-1) at 1.2 V. The values of the effective diffusion coefficient obtained from neutron imaging experiments can be used to evaluate model predictions of the ion transport rate in capacitive deionization and electrochemical energy-storage devices.

Natural convection of a paramagnetic liquid controlled by magnetization force

AbstractRayleigh–Benard natural convection of aqueous gadolinium nitrate solution (paramagnetic) was studied experimentally and numerically in the presence of upward magnetization force in a framework similar to that proposed by Braithwaite et al. With the magnetic susceptibility of the gadolinium nitrate solution reevaluated by the Gouy method, the measured heat transfer rates were found to agree with Silveston's experimental curve, which represents the relationship between the Nusselt number (Nu) and the magnetic Rayleigh number (Ram). Furthermore, three‐dimensional numerical computations were also carried out. Every convection flow pattern became axisymmetric, and the computed Nu agreed with Silveston's curve when Ram was used in place of the Rayleigh number. © 2005 American Institute of Chemical Engineers AIChE J, 2005

Structural transformations and phase transitions in aqueous solutions of gadolinium nitrate in the course of freezing

The microstructure of Gd(NO3)3 aqueous solutions in the course of cooling at different rates is investigated using electron paramagnetic resonance. The local concentrations of Gd3+ ions in microregions are estimated, the concentration boundary at which the solution is completely vitrified throughout its volume is revealed, and the temperature of vitrification of liquid microregions (eutectic temperature) and the eutectic composition are determined. It is found that the adsorption of Gd3+ aqua ions on the capillary surface affects the crystallization of water and the process of concentration of the solute. It is demonstrated that the anomalous experimental dependence δH(C0), which is observed for vitrified water-glycerol solutions with a uniform distribution of paramagnetic centers over the sample, agrees well with the theoretical curve in the case when allowances are made not only for the dipole-dipole interactions but also for the inhomogeneous broadening of the EPR lines in the spectra with an incompletely resolved fine structure.

Toxicity of gadolinium to some aquatic microbes.

The toxicity of gadolinium to algae and bacteria was determined as part of an effort to develop a biological process to purify drums containing spent nuclear reactor heavy water moderator (D2O). This water was contaminated with high concentrations of gadolinium nitrate, a chemical used as a neutron poison during former nuclear reactor operations at the Savannah River Site (SRS) near Aiken, SC. Nuclear reactors were operated for approximately 30 years at the SRS to produce nuclear weapons materials for national defense. Throughout this period, a heavy water solution of gadolinium nitrate was utilized in a standby emergency shutdown system that could inject this chemical into the reactor moderator coolant water. The chemical was used for this purpose because the high neutron absorption cross sections of some gadolinium isotopes make gadolinium salts such as GdNO3 effective in controlling nuclear activity in aqueous systems (Gilbert et al. 1985; Rodenas et al. 1990). The use of this practice resulted in a large inventory of this degraded heavy water containing gadolinium nitrate. Microbiological and chemical studies were initiated to evaluate the potential use of bacteria and algae for water purification of the drums. Since metals are often toxic to microbes when present at concentrationsmore » substantially higher than natural environmental levels, it was hypothesized that Gd may be toxic to selected microorganisms (algae and bacteria) at the very high concentrations (average 80,000 mg/L, maximum 259,000 mg/L) present in most of the drums. Two principal components of the study included: (1) chemical and microbiological characterization of representative drums, and (2) an evaluation of the toxicity of gadolinium to selected species of algae. In addition to wastewater from nuclear production reactor operations, gadolinium waste is also generated from medical applications, especially MRI, and various electronic components including CD disks. Despite growing and widespread usage of this rare element, there is a paucity of information on the toxicity of gadolinium.« less

Characterization and thermal behavior of HGdP 2O 7·3H 2O

Crystals of the trihydrated gadolinium diphosphate HGdP 2O 7·3H 2O were obtained from a mixture of diphosphoric acid and gadolinium nitrate solutions. This salt was characterized by X-ray powder diffraction, IR spectroscopy and thermal analysis. IR spectroscopic study reveals the existence of the characteristic band of the P 2O 7 group, the ν as(POP) band, at 941 cm −1 and the absence of the ν s(POP) one. The thermal decomposition of HGdP 2O 7·3H 2O, which was followed by thermogravimetry and differential scanning calorimetry, shows that the elimination of the crystallization water takes place in three stages between 71 and 500°C. The overall ΔH of the first two dehydration were found to be 41.06 and 25.88 kJ/mol. New well-crystallized hydrates HGdP 2O 7·1.5H 2O and HGdP 2O 7·0.5H 2O were obtained through heating HGdP 2O 7·3H 2O, respectively, at 145 and 280°C. The anhydrous HGdP 2O 7 salt, which was obtained by calcination of HGdP 2O 7·3H 2O at 530°C, decomposes at 700°C with loss of P 2O 5 to give the gadolinium diphosphate Gd 4(P 2O 7) 3.