Ethylenediaminetetraacetic Acid Disodium Salt Dihydrate Research Articles

Separation of heavy (dysprosium) and light (praseodymium, neodymium) rare earth elements using electrodialysis

This work reports electrodialysis studied to separate dysprosium (Dy, a heavy rare earth element (REE)) from praseodymium and neodymium (Pr, Nd, a mixture of light REEs). A unique electrodialysis setup comprising a cation exchange membrane, a PC-400D membrane (anion exchange membrane that transfers large organic anions), and an anion exchange membrane is used. To achieve the separation of these REEs, ethylenediaminetetraacetic acid disodium salt dihydrate is used as the chelating agent. Because of the higher stability constant of EDTA with Dy(III) compared with Pr(III) and Nd(III), most of EDTA form [Dy-EDTA]− chelate which upon applying electric potential move from the feed to the concentrate compartment through the PC-400D membrane, leaving behind free Pr and Nd cations in the feed compartment. The effect of rinse solution concentration (sodium sulfate, 0.05–0.07 mol/L), applied electric potential (10–14 V), feed pH (2–5), and EDTA concentration (EDTA/Dy molar ratio of 0.9–1.2) on key performance indicators of electrodialysis, i.e., purity, yield, separation factor, and Dy removal efficiency is investigated. Rinse solution concentration has a negligible effect on the separation performance in the studied range. Applied potential shows a positive effect on the Dy removal efficiency, but separation factor decreases with increasing potential above 12 V. The suitable pH range for maximum separation performance is found to be above 3 and below 5. Increasing EDTA/Dy molar ratio increases the amount of Pr and Nd chelates with EDTA, which also move to the concentrate compartment and decrease the product purity. The ratio 1:1 is found to result in the highest Dy purity and separation factor. The rinse solution concentration of 0.05 mol/L with 12 V applied potential, pH 4, and EDTA/Dy molar ratio of 1.0 result in a separation factor of 125 which is promising. Under this set of conditions, a Dy purity of 93% and Dy yield of 77% is achieved.

Reversible Morphology Locking via Metal Infiltration in a Block Copolymer.

Metal infiltration from an acid solution of a metal precursor into the poly(2-vinylpyridine) (P2VP) microdomains of a polystyrene-b-P2VP block copolymer is shown to reduce the uptake of solvent vapor during a subsequent solvent annealing process, locking the morphology of the self-assembled microdomains. The amount of metal, here Pt, incorporated into the P2VP increases with both metal precursor [PtCl4]2- and hydrochloric acid concentrations, reaching 0.83 Pt atom per pyridine unit. The metal is then exfiltrated using a KOH + ethylenediaminetetraacetic acid disodium salt dihydrate (Na2EDTA) complexing solution, which restores solvent uptake and unlocks the morphology. The reversibility of the metal infiltration and morphology locking is demonstrated in a multistage annealing process and is confirmed for Fe as well as Pt. Reversible locking and unlocking of block copolymer microdomain morphologies expand their utility for nanofabrication processes by allowing the morphology to be fixed during subsequent process steps.

The effects of Pt cocatalyst particle size on charge transfer kinetics in dye-sensitized SrTiO3 photocatalysts for hydrogen evolution studied by time-resolved emission/absorption spectroscopy

Dye-sensitized H2 evolution systems were constructed from Pt-loaded SrTiO3 and Ru(II) complex photosensitizers as building blocks, and the impact of the Pt cocatalyst was investigated. In the presence of a stronger electron donor (sodium ascorbate), SrTiO3 loaded with larger Pt particles showed higher activity. On the other hand, the sample having smaller Pt particles gave higher activity in the presence of a weaker electron donor (ethylenediaminetetraacetic acid disodium salt dihydrate). Time-resolved emission/absorption measurements revealed that the larger Pt particles facilitated electron injection from the excited Ru sensitizer to Pt/SrTiO3, while the smaller one improved charge carrier separation by suppressing the back electron transfer reaction from Pt/SrTiO3 to the oxidized sensitizer. These results show that the cocatalyst particle size can affect the kinetics of the electron injection and carrier separation processes. Judicious choice of the Pt particle size can therefore improve the H2 evolution activity in accordance with the reaction system.

Photopolymerization with EDTA and Riboflavin for Proteins Analysis in Polyacrylamide Gel Electrophoresis.

A new method for photosensitized polymerization of polyacrylamide gels was proposed. Photopolymerization of acrylamide/N,N'-methylenebisacrylamide (AM/Bis) was assisted with combination of catalyst ethylenediaminetetraacetic acid disodium salt dihydrate (EDTA) and photoinitiator riboflavin (RF). The prepared cross-linked AM/Bis + EDTA/RF gels were tested in electrophoretic SDS-PAGE system at high concentration of AM (20 wt%). The efficiency of these systems for electrophoretic separation of histones of human blood lymphocytes was demonstrated. In principle, such gels with small pores in the separation zone can offer advantages for resolution of proteins. The advantages of proposed method also include simple technique and possibility of gel preparation in a timely manner (for 10-15min). However, in microporous gel systems some limitations in electroblotting technique could occur, which is particularly crucial for hydrophobic proteins.

Encapsulation of NiS and ZnS in analcime nanoparticles as novel nanocomposites for the effective photocatalytic degradation of orange G and methylene blue dyes

ABSTRACT Encapsulation of semiconductor materials in zeolites is one of the important types of composites that have been used as photocatalysts in the degradation of several organic dyes. The high surface area and uniform porous structure of the zeolite particles prevent the coagulation of the catalyst and ensure its stability and dispersion. The strong polarised electrostatic field of zeolites can decrease the energy consumption needed to facilitate the electrons transfer from the valence band to the conduction band. So, in this paper, ethylenediaminetetraacetic acid disodium salt dihydrate was used as an organic template to hydrothermally synthesise analcime nanoparticles. Besides, NiS and ZnS were encapsulated in the analcime nanoparticles as novel photocatalysts for the efficient degradation of orange G and methylene blue dyes. EDX, XRD, FE-SEM, FT-IR, HR-TEM, diffuse reflectance spectrophotometer, and nitrogen gas sorption instruments were used to characterise the novel photocatalysts. The XRD results confirmed that the encapsulation of NiS or ZnS in the analcime nanoparticles led to a decrease in the intensity of the peaks only without affecting their positions. The FE-SEM images confirmed that the encapsulation of NiS or ZnS in the analcime nanoparticles changed the surface of the analcime from small spherical particles into large spherical particles, in addition to the presence of irregular shapes. Besides, the nitrogen gas sorption analyser confirmed that the encapsulation of NiS or ZnS in the analcime nanoparticles led to an increase in average pore radius and total pore volume and a decrease in BET surface area. The percentage of photocatalytic degradation of orange G dye using NiS/analcime and ZnS/analcime composites is 63.60 and 70.50%, respectively. The percentage of photocatalytic degradation of methylene blue dye using NiS/analcime and ZnS/analcime composites is 88.76 and 98.31%, respectively.

Facile synthesis of sulfur and oxygen co-doped graphitic carbon nitride quantum dots for on-off detection of Cu2+ in real samples and living cells

A fluorescent sulfur and oxygen co-doped graphitic carbon nitride quantum dots (S,O-CNQDs) were prepared from ethylenediaminetetraacetic acid disodium salt dihydrate and thiourea as the carbon and sulfur sources. The morphology and surface functional groups of S,O-CNQDs were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The fluorescence of S,O-CNQDs could be quenched efficiently by Cu2+ under the optimum conditions. The S,O-CNQDs could function as an excellent fluorescent probe for Cu2+ detection with a wide linear range of 0.50–15 μM and a low detection limit of 0.58 nM. In addition, this fluorescent probe was employed for monitoring Cu2+ in samples of tap water, lake water, human serum and urine with good recoveries from 99.0% to 110.0%. Moreover, the S,O-CNQDs with high cell penetration and low cytotoxicity were utilized for Cu2+ detection in living cells. Owing to the excellent properties of S,O-CNQDs, the as-prepared S,O-CNQDs can be a potential candidate for biological applications.

Construction of turn-on mode fluorescent sensor for Pb<sup>2+</sup> and Al<sup>3+</sup> with structure of phthalic acid and tetraphenylethylene core

<p indent="0mm">Lead is one of the most hazardous metals to humans. It accumulates in liver, kidney and central nervous system, and interferes with a variety of physiological processes such as biosynthesis of hemoglobin. Lead is especially dangerous for children, causing mental retardation. Aluminum has an important role in Alzheimer’s disease, Parkinson’s disease, bone softening, chronic renal failure. However, both lead and aluminum are widely used in industrial applications and daily life. The limits of Pb²⁺ and Al³⁺ for drinking water according to the World Health Organization (WHO) standard are 0.5 and <sc>7.41 µmol/L</sc> respectively. Thus, it is necessary to develop real-time and rapid detection of Pb²⁺ and Al³⁺. Fluorescent probes are favored by researchers because of their high sensitivity and selectivity, rapid real-time monitoring and potential application in biological systems. The emission of the traditional panel-like chromophore is weakened or even quenched at high concentration or aggregation, while at low concentration, it exhibits low sensitivity and is easy to photobleaching. Tang and coworkers noticed that some luminogens with twisted conformations are nearly nonemssive in solution but exhibit boosted emission in aggregate states, thus, Tang coined this phenomenon as aggregation induced emission (AIE). With the disclosure of the AIE mechanism of restriction of motion (RIM), many AIE active luminogens have been developed. Some turn-on mode fluorescent sensors for Pb²⁺ and Al³⁺ have also been reported based on AIE mechanism, but few of them worked in pure water. Two water-soluble fluorescent sensors are constructed using phthalic acid structure as electron acceptor and tetraphenylethylene as core: 4,4′-(2,2-diphenylethene-1,1-diyl)diphthalic acid (<bold>1</bold>) and 4,4′-(2,2-bis(4-(dimethylamino)phenyl)ethene-1,1-diyl)diphthalic acid (<bold>2</bold>). Both <bold>1</bold> and <bold>2</bold> are nearly nonemissive in solution, but their solids are highly luminescent with quantum yield of 17.1% and 7.3%. Emission of <bold>1</bold> and <bold>2</bold> in water in the presence of KOH is turned on upon addition of Pb²⁺ or Al³⁺, while exhibit nearly no response to the addition of other metal ions, indicating the high selectivity for Pb²⁺ or Al³⁺. The detection limit of <bold>1</bold> and <bold>2</bold> towards Al³⁺ was estimated as 2 and <sc>0.17 µmol/L,</sc> which meets the limit for drinking water according to the WHO standard <sc>(7.41 µmol/L).</sc> Fluorescent intensities of <bold>1</bold> and <bold>2</bold> enhanced by Pb²⁺ and Al³⁺ are not much affected by the existence of the interfering ions. The exception is that the emission intensity of <bold>1</bold> can be greatly enhanced by Zn²⁺ when detecting Pb²⁺, which may afford the the construction for highly sensitive sensors for Pb²⁺ through combination of <bold>1</bold> and Zn²⁺. The average particles size of <bold>1</bold> and <bold>2</bold> in water solution are 36 and <sc>98 nm</sc> determined by dynamic light scattering (DLS) analysis, respectively. The average particles size of <bold>1</bold> increased to 707 and <sc>292 nm</sc> upon addition of Pb²⁺ and Al³⁺, respectively. And average particles size of <bold>2</bold> increased to 986 and <sc>906 nm</sc> upon addition of Pb²⁺ and Al³⁺. Thus the emission enhancement of <bold>1</bold> and <bold>2</bold> upon addition of Pb²⁺ and Al³⁺ should be caused by the aggregate formation. The emissions of the water solutions of <bold>1</bold> or 2 in the presence of Pb²⁺ or Al³⁺ were quenched upon addition of ethylenediaminetetraacetic acid disodium salt dihydrate (EDTA-2Na) due to the competing coordination of EDTA-2Na with metal ions.

Induction of hypocalcaemia and evaluation of reticuloruminal motility using a three-axis accelerometer

Context Reticuloruminal motility, which is continuous and regular, is essential for digestive activity, but some functional abnormalities can appear in cattle with several metabolic disorders. Particularly in periparturient dairy cows, decreased blood calcium concentrations induce deterioration of rumen motility as well as the risk of reproductive disorders. Aims This study aimed to evaluate reticuloruminal motility using a bolus-type biosensor incorporated with a three-axis accelerometer (3XA) following induction of hypocalcaemia by infusion of ethylenediamine–tetraacetic acid disodium salt dihydrate (Na2EDTA) solution. Methods In the 2 × 2 crossover experiment, six non-pregnant and non-lactating cows were assigned to each of the treatment (TRE) and control (CON) groups and infused for 1 h with 13% Na2EDTA solution and physiological saline respectively. The cylindrical biosensor was fed and placed in the reticulum before the experiment, and the three acceleration values of each cow were recorded and transmitted wirelessly. Considering the device shape, the reticuloruminal motility was represented as the vector value (V2) calculated with each change in X- and Z-axis acceleration over time. Key results Plasma calcium concentrations were measured to confirm hypocalcaemia, and the average was significantly decreased to 1.23 mmol/L at 1 h in TRE. The mean V2 value was significantly decreased in TRE compared with CON, from 1 to 2 h after Na2EDTA infusion. Conclusion 3XA was able to detect a change in reticuloruminal motility caused by hypocalcaemia. The use of 3XA in cattle will allow for rapid treatment of hypocalcaemia or other metabolic disorders that reduce productivity. Implications The 3XA inserted into the reticulum of a dairy cow detected a decrease in reticuloruminal motility wirelessly caused by induced hypocalcaemia.

Determination of multiple antibiotics in agricultural soil using a quick, easy, cheap, effective, rugged, and safe method coupled with ultra-high performance liquid chromatography-tandem mass spectrometry.

In this study, we combined ultra-high performance liquid chromatography with tandem mass spectrometry to establish a quick, easy, cheap, effective, rugged, and safe method of detecting 21 target antibiotics in agricultural soil samples. Antibiotics were extracted with mixed solvents consisting of ethylenediaminetetraacetic acid disodium salt dihydrate and phosphoric acid citric acid buffer and acetonitrile which were purified with octadecylsilyl as an adsorbent and anhydrous sodium sulfate as a desiccant. This method was able to effectively extract all of the target antibiotics from agricultural soils, with recovery efficiencies ranging from 55 to 108% and limits of detection between 0.09-0.68 μg/kg. We also validated this new method for selectivity, sensitivity, and reliability of detecting multiple antibiotics in 12 samples. Considering the potential environmental and public health effects of antibiotics in agricultural soils, our new method can help analyze the degree of antibiotic contamination and provide valuable information for soil quality and risk assessment.

Amino acid derivative reactivity assay-organic solvent reaction system: A novel alternative test for skin sensitization capable of assessing highly hydrophobic substances.

The amino acid derivative reactivity assay (ADRA) is an in chemico alternative to animal testing that focuses on protein binding. The ADRA is a skin sensitization test that solves problems associated with the direct peptide reactivity assay. However, when utilizing the ADRA to evaluate highly hydrophobic substances with octanol/water partition coefficients (logKow) of >6, the test substances may not dissolve in the reaction solution, which can prevent the accurate assessment of skin sensitization. Therefore, we developed the ADRA-organic solvent (ADRA-OS) reaction system, which is a novel skin sensitization test that enables the assessment of highly hydrophobic substances with a logKow of >6. We discovered that the organic solvent ratio, the triethylamine concentration, and the ethylenediaminetetraacetic acid disodium salt dihydrate concentration participate in reactions with the nucleophile N-(2-(1-naphthyl)acetyl)-l-cysteine (NAC) and sensitizers that are used in ADRA and in stabilizing NAC. Thus, we determined the optimal reaction composition of the ADRA-OS according to L9 (33 ) orthogonal array experiments. Using this test, we assessed 14 types of highly hydrophobic substances. When we compared the results with ADRA, we found that ADRA-OS reaction system has high solubility for highly hydrophobic substances and that it has a high predictive capacity (sensitivity: 63%, specificity: 100%, accuracy: 79%). The implication of the results is that the novel ADRA-OS reaction system should provide a useful method for assessing the skin sensitization of highly hydrophobic substances with a logKow of >6.

Synergetic activation of persulfate by heat and Fe(II)-complexes for hydrolyzed polyacrylamide degradation at high pH condition: Kinetics, mechanism, and application potential for filter cake removal during cementing in CO2 storage wells

The long-term integrity of the interface between cement and formation rock in CO2-capture and storage wells is crucial to avoid leakage of CO2 in/along wells. However, the interface can be easily damaged by the filter cake, which is a compressed composite of bentonite, polymers such as hydrolyzed polyacrylamide (HPAM), and barite, on the wellbore rock. Therefore, removing the filter cake during the cementing process by degrading HPAM in an efficient way is essential. In this study, chelated-Fe2+ activated potassium persulfate (KPS) was used for HPAM degradation and filter-cake removal. Ethylenediaminetetraacetic acid disodium salt dihydrate (EDTA-2Na) and diethylenetriaminepentaacetic acid (DTPA) were adopted to control the precipitation of Fe2+/Fe3+. A mixture of 0.4 mM Fe2+, 0.8 mM DTPA, and 4 mM KPS at a pH of 10.0 at 70 °C reduced the molecular weight of HPAM significantly from 3.0 × 106 to (3.6–10) × 104 Da. Electron paramagnetic resonance (EPR) analysis suggested that HO was the dominant radical and that SO4− and O2− were responsible for the degradation. The reactions conformed to continuous distribution kinetics with an activation energy of 38.36 kJ mol−1. A possible degradation pathway was proposed based on analyses via infrared spectroscopy (IR) and time-of-flight liquid chromatography-mass spectrometry (TOF-LC/MS). >90 wt% of the filter cake was removed by the system. The results suggest that the proposed DTPA-Fe2+ activated KPS system exhibits promising potential for in situ degradation of high molecular weight HPAM and for the removal of filter cake in downhole wells.

Transformation of industrial steel slag with different structure-modifying agents for synthesis of catalysts

Abstract Industrial slag containing Si, Al, Ca, Fe, Mg and Ti was used as source for synthesis of novel catalytic materials upon variation of the treating agents (sodium hydroxide, ethylenediaminetetraacetic acid disodium salt dihydrate - sodium hydroxide and tetraethylammonium hydroxide - sodium hydroxide mixtures) and synthesis parameters (solution concentration, synthesis temperature and time). Physico-chemical properties of the raw slag and the catalysts were evaluated by nitrogen physisorption, scanning electron microscopy, energy dispersive X-ray analysis, temperature programmed desorption of CO2 and NH3, transmission electron microscopy, and X-ray powder diffraction. Catalytic activity of the most promising slag-based material was investigated in analytical pyrolysis of wood biomass. Synthesized materials exhibited highly crystalline phases of CaCO3, Ca(OH)2, Ca2SiO4, SiO2, Al2O3, Fe2O3,and TiO2 and showed high basicity due to the presence of large amounts of basic components. Treatment with surfactants had a significant influence on formation of acid sites. Modification of slag textural properties and internal porous structure by such treatment resulted in formation of pores and channels depending on the leaching agent. Upon variation of a leaching agent the specific surface area of the raw slag could be changed from 19 m2/g up to 80 m2/g, what turned out to be important in creation of an effective catalyst for biomass pyrolysis. Slag treatment improved its catalytic activity, which was evidenced by variations of the liquid yield and composition of pinewood derived compounds in non-catalytic and catalytic pyrolysis using original slag and the catalysis synthesized on its basis.

Experimental Measurement of the Solid–Liquid Equilibrium of the Systems MF2 + H2O (M = Mg, Ca, Zn) from 298.15 to 353.15 K

The solubility of MgF2, CaF2, and ZnF2 in aqueous solution is seldom studied. Their solubility data available in the literature conflict with each other, and their change tendency with temperature is hard to draw. In this work, we elaborately measured their solubility over the temperature range from 298.15 to 353.15 K. To guarantee the data reliability, various methods including ethylenediamine tetraacetic acid disodium salt dihydrate (EDTA) titration and fluoride ion selective electrode (FISE) have been used for ion content analysis in the saturated solutions and X-ray diffraction (XRD) for equilibrium solid phase identification. Besides, sufficient solid–liquid contact time has been taken to guarantee the equilibrium. The determined results were compared with those reported in the literature, and their differences have been discussed. It was found that the MgF2 solubility decreases; however, the CaF2 solubility increases with increasing temperature. In the ZnF2 + H2O system, the equilibrium solid phase ...

Measurement and Correlation for the Solid Solubility of Antioxidants of EDTA Disodium Salt Dihydrate, EDTA Calcium Disodium Salt Hydrate, and l-Cysteine Hydrochloride in Supercritical Carbon Dioxide

This research focuses on measuring the solubility of three antioxidants—ethylenediaminetetraacetic acid disodium salt hydrate, ethylenediaminetetraacetic acid calcium disodium salt hydrate, and l-cysteine hydrochloride—in supercritical carbon dioxide. Using a semiflow apparatus, the experiment takes data at 308.15, 313.15, and 318.15 K with pressure ranging from 10 to 22 MPa (for ethylenediaminetetraacetic acid disodium salt dihydrate) or from 12 to 24 MPa (for ethylenediaminetetraacetic acid calcium disodium salt hydrate and l-cysteine hydrochloride). Two semiempirical equations—one proposed by Chrastil, the other Mendez-Santiago and Teja—are applied to find the correlated relationship of the experimental data. With the choice of fitted parameters, the correlation derived from the two equations are satisfactory: the average absolute relative deviation is under 5.1%.

Surfactant-assisted hydrothermal synthesis of Fluoridated Hydroxyapatite nanorods

Fluoridated Hydroxyapatite (FHA) nanorods were synthesized using Apricot Tree Gum (ATG) as a novel surfactant and then compared with Ethylenediaminetetraacetic acid disodium salt dihydrate (EDTA) and Sodium Dodecyl Sulfate (SDS) as conventional surfactant agents under hydrothermal condition (70°C and 1atm). The effects of pH values and various types of surfactants on the formation of the FHA nanorods, crystalline phase, and chemical compositions were investigated using Field Emission Scanning Electron Microscopy (FESEM) equipped by Energy Dispersive X-ray (EDX), X-Ray Diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR). The findings indicated application of the presented ATG as surfactant is able to produce the hexagonal nanorods of FHA along their c-axis direction. Moreover, it is illustrated that diameter and length of nanorods which is obtained by ATG surfactant are bigger than EDTA and SDS. In addition, it is demonstrated that pH values can play a major role on formation of hexagonal FHA nanorods. The increase of pH transformed the shape of synthesized FHA from particles to rods. Ultimately, based on the similarity of synthesized FHA nanorods to the shape, structure, and composition of enamel; it is suggested for its potential to be used for dental applications.

Preparation of the Ag–Zn–Sn–S quaternary photoelectrodes using chemical bath deposition for photoelectrochemical applications

Quaternary Ag–Zn–Sn–S thin films were deposited onto the surface of indium-tin-oxide-coated glass substrates using chemical bath deposition. The procedures for the growth of Ag–Zn–Sn–S semiconductor films are presented. The optical, physical and photoelectrochemical performances of the samples were investigated. The X-ray diffraction patterns of the samples reveal that tetragonal Ag2ZnSnS4 phase with small amount of impurities, such as Ag8SnS6, can be obtained using 0.4M ethylenediaminetetraacetic acid disodium salt dihydrate as the chelating agent and deposition temperature kept at 70°C. The major phase of other samples prepared in this study was the Ag8SnS6 phase. The energy band gaps of the samples are in the range of 2.08 to 2.56eV, depending on the compositions. The maximum photoelectrochemical performance of samples in this study was 0.65mAcm−2 at an external potential of +1.0V vs. an Ag/AgCl electrode in aqueous K2SO3 and Na2S solution at an irradiation of 100mWcm−2, using a Xe lamp as the light source.

Preparation of silica-coated gadolinium compound particle colloid solution and its application in imaging

A preparation method for gadolinium compound (GdC) nanoparticles coated with silica (GdC/SiO2) is proposed. GdC nanoparticles were prepared with a homogeneous precipitation method at 80oC using 1.0x10-3 M Gd(NO3)3, 0.5 M urea and 0-3.0x10-4 M ethylenediaminetetraaceticacid disodium salt dihydrate (ETDA) in water. As a result of preparation at various EDTA concentrations, GdC nanoparticles with a size as small as 40.5+-6.2 nm, which were colloidally stable, were prepared at an EDTA concentration of 2.0x10-4 M. Silica-coating of the GdC nanoparticles was performed by a Stober method at 35oC using 1.0-10.0x10-3 M tetraethylorthosilicate (TEOS), 11 M H2O and 1.5x10-3 M NaOH in ethanol in the presence of 1.0x10-3 M GdC nanoparticles. Performance of preparation at various TEOS concentrations resulted in production of GdC/SiO2 particles with an average size of 106.1+-11.2 nm at a TEOS concentration of 5.0x10-3 M. The gadolinium (Gd) concentration of 1.0x10-3M in the as-prepared GdC/SiO2 particle colloid solution was increased up to a Gd concentration of 0.2 M by concentrating with centrifugation. The core-shell structure of GdC/SiO2 particles was undamaged, and the colloid solution was still colloidally stable, even after the concentrating process. The concentrated GdC/SiO2 colloid solution showed images of X-ray and magnetic resonance with contrast as high as commercial Gd complex contrast agents.

Fabrication of hollow particles composed of silica containing gadolinium compound and magnetic resonance imaging using them

A preparation method for hollow particles composed of silica shell containing gadolinium compound (GdC) is proposed. GdC nanoparticles with an average size of 40.5 ± 6.2 nm were prepared with a homogeneous precipitation method at 80°C using 1.0 × 10−3 M Gd(NO3)3 and 0.5 M urea in the presence of 2.0 × 10−4 M ethylenediaminetetraacetic acid disodium salt dihydrate. Silica-coated GdC (GdC/SiO2) nanoparticles with an average size of 100.9 ± 9.9 nm were fabricated with a sol-gel method at 35°C using 5.0 × 10−3 M tetraethylorthosilicate, 11 M H2O, and 1.5 × 10−3 M NaOH in ethanol in the presence of 1.0 × 10−3 M GdC nanoparticles. The GdC/SiO2 particles were aged at 80°C in water after replacement of solvent of the as-prepared GdC/SiO2 particle colloid solution with water, which provided diffusion of GdC into the silica shell and then formation of a hollow structure. The hollow particle colloid solution revealed good MRI properties. A relaxivity value for longitudinal relaxation time-weighted imaging was as high as 3.38 mM−1 · s−1 that attained 80% of that for a commercial Gd complex contrast agent.

Rapid separations of nile blue stained microorganisms as cationic charged species by chip‐CE with LIF

Rapid detection of microorganisms by alternative methods is desirable. Electromigration separation methods have the capability to separate microorganisms according to their charge and size and laser-induced fluorescence (LIF) detection have single-cell detection capability. In this work, a new combined separation and detection scheme was introduced using chip-based capillary electrophoresis (chip-CE) platform with LIF detection. Three microorganisms Escherichia coli, Staphylococcus aureus, and Candida albicans were selected as representatives of Gram-positive bacteria, Gram-negative bacteria, and fungi. While their cells carry an overall negative charge in neutral to alkaline pH, staining them with nile blue (NB) provided highly sensitive LIF detection with excitation and emission wavelengths at 635 nm and 685 nm, respectively, and at the same time, the overall charge was converted to positive. Electrolyte pH and concentration of polyethylene oxide (PEO) significantly affected the resolution of the microorganisms. Their optimal separation in the 14 mm separation channel was achieved in less than 30 s (R(s) > 5.3) in an electrolyte consisting of 3.94 mM Tris, 0.56 mM boric acid, 0.013 mM ethylenediaminetetraacetic acid disodium salt dihydrate (pH 10.5), and 0.025% PEO, with injection/separation voltages of +1000/+1000 V. The separation mechanism is likely employing contributions to the overall cationic charge from both the prevalently anionic membrane proteins and the cationic NB. Importantly, the resulting cationic NB-stained cells exhibited excellent separation selectivity and efficiency of ∼38000 theoretical plates for rapid separations within 30-40 s. The results indicate the potential of chip-CE for microbial analysis, which offers separations of a wide range of species with high efficiency, sensitivity, and throughput.

EDTA-Assisted Self-Assembly of Fluoride-Substituted Hydroxyapatite Coating on Enamel Substrate

Reconstructed layers containing ordered enamel-like structures of fluoride-substituted hydroxyapatite (FHAp) microcrystals were constructed on a human enamel surface using ethylenediaminetetraacetic acid disodium salt dihydrate (EDTA) as the mediating agent under near-physiological conditions (pH 6.00, 37 °C, 1 atm). The effects of initial pH value, fluoride concentration, as well as reaction time on the formation of the FHAp microcrystals, including their microarchitectural structure, crystalline phase, chemical components, and hardness properties, were investigated using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Vickers microhardness measurements. The results of these in vitro experiments indicated that EDTA induced the assembly of hexagonal prismlike FHAp microcrystals along their c-axis direction, and the microcrystals further amalgamated with the extended reaction time. In addition, fluoride ions were found to play a critical role in the formation of hexagonal FHAp microcrystals. Interestingly, after reaction for 5 days, the Vickers microhardness of the new layer (347–370 VHN) was harder than that of natural tooth. On the basis of the experimental evidence, a mesoscale self-assembly mechanism was proposed to explain the growth of FHAp microcrystals.