Novel Diglycolamic Acid Functionalized Iron Oxide Particles for the Mutual Separation of Eu(III) and Am(III)

Iron oxide (Fe₃O₄) particles functionalized with diglycolamic acid (Fe-DGAH) were synthesized and characterized by TG-DTA, X-Ray diffraction,¹H NMR, and scanning electron microscopy (SEM). The extraction behavior of Am(III) and Eu(III) in Fe-DGAH was studied from dilute nitric acid medium to examine the feasibility for the mutual separation of trivalent actinides and lanthanides using Fe-DGAH. For this purpose, the effect of various parameters such as the duration of equilibration and concentrations of europium, nitric acid, and diethylenetriaminepentaacetic acid (DTPA) in the aqueous phase on the distribution ratio (K_d) of Am(III) and Eu(III) was studied. The conditions needed for the efficient separation of Am(III) from Eu(III) were optimized using DTPA. The distribution ratio of ?10⁴ mL/g was obtained for both Am(III) and Eu(III) at pH 3, and it decreased with an increase in the concentration of nitric acid. However, a separation factor of Eu(III) over Am(III) of ?150 was achieved in the presence of DTPA. Rapid sorption of metal ions in the initial stages of equilibration followed by the establishment of equilibrium occurred within 2 h. The sorption data were fitted to the Langmuir adsorption model, and the apparent europium sorption capacity was determined to be ?50 mg/g. The study indicated the feasibility of using Fe-DGAH particles for magnetic separation of Eu(III) from Am(III) with high separation factors.     

Determination of neodymium(III) ions in soil and sediment samples by a novel neodymium(III) sensor based on benzyl bisthiosemicarbazone

The PVC membrane, containing benzyl bisthiosemicarbazone (BTC) as a suitable ionophore, exhibited a Nernstian response for the Nd³⁺ ions over a wide concentration range between 1.0 × 10⁻² and 1 × 10⁻⁶ M, with a detection limit of 6.2 × 10⁻⁷ M in the pH range of 3.7-8.3. It demonstrated a fast response time (<10 s) and it could be used for at least 7 weeks without any major potential deviation. Furthermore, the electrode revealed high selectivity with respect to all the common alkali, alkaline earth, transition and heavy metal ions, including the members of the lanthanide family other than Nd³⁺. Concerning its applications, it was effectively employed for the determination of neodymium ions in soil and sediment samples and its validation with CRM.     

Synthesis and photoluminescence properties of MgAl(PO4)O:Eu red phosphor for white LEDs

Eu³⁺-activated MgAl(PO₄)O:phosphor has been synthesized by a high temperature solid state reaction and efficient red emission under near-ultraviolet excitation is observed. The emission spectrum shows a dominant peak at 594 nm due to the ⁵D₀→⁷F₁ transition of Eu³⁺. The excitation spectrum is coupled well with the emission of UV LED (350–410 nm). The effect of Eu³⁺ concentration on the luminescent properties of MgAl(PO₄)O:Eu³⁺ and the mechanism of concentration quenching of Eu³⁺ are studied. The results show that MgAl(PO₄)O:Eu³⁺ is a promising red-emitting phosphor for white LEDs.     

Selective Separation of Nickel (II) and Cobalt (II) from Waste Water by Using Continuous Cross-Flow Micellar Enhanced Ultrafiltration with Addition of Chelating Agent

The performance of continuous cross-flow micellar enhanced ultrafiltration (MEUF) is evaluated for the selective separation of nickel (Ni²⁺) and cobalt (Co²⁺) from the aqueous stream using anionic surfactant sodiumdodecyl sulfate (SDS) and the mixture of the anionic and nonionic surfactant (SDS+TritonX-100) with the addition of iminodiacetic acid (IDA) as a chelating agent. Operating parameters like operating time (upto 100 min), cross flow rate (100–175 mL/min.), pH of the feed solution (3-6 Cheryan , M. ( 1998 ) Process Design in Ultrafiltration and Microfiltration Handbook ; Technomic Publishing Co. Inc : USA . Scamehorn , J.F. ; Ellington , R.T. ; Christian , S.D. ; Penny , B.W. ; Dunn , R.O. ; Bhat , S.N. ( 1986 ) Removal of multivalent metal cations from water using micellar-enhanced ultrafiltration . AIChE Symp. Ser. , 82 ( 250 ): 48 – 58 . Baek , K. ; Yang , J.W. ( 2004 ) Cross flow micellar-enhanced ultrafiltration for removal of nitrate and chromate: competitive binding . J. Hazard. Mater. , B108 : 119 – 123 . Yurlova , L. ; Kryvoruchko , A. ; Kornilovich , B. ( 2002 ) Removal of Ni (II) ions from waste- water by micellar-enhanced ultrafiltration . Desal. , 144 : 255 – 260 . ), molar concentration ratio of the chelating agent to metals (C/M ratio, 0.5–2.5), and molar concentration ratio of the surfactant to metals (S/M ratio, 5–9) were studied to investigate the effectiveness of the process on selective separation. For the single surfactant system at all empirically selected parameters, 92% Ni²⁺ in the permeate and 94% Co²⁺ in the retentate was achieved whereas for the mixed surfactant system 93% Ni²⁺ in permeate and 84% Co²⁺ in retentate was achieved. Flux variation for single and mixed surfactant system was studied. Flux observed for the single surfactant system was 36 L/m².h and for the mixed surfactant system was 31.5 L/m².h. Flux measurement also indicates insignificant fouling of the membrane.     

Functionalized magnetic core-shell Fe3O4@SiO2 nanoparticles as selectivity-enhanced chemosensor for Hg(II)

A colorimetric and ‘‘turn-on” fluorescent chemosensor Rho-Fe₃O₄@SiO₂ for Hg²⁺ in which N-(rhodamine-6G)lactam-ethylenediamine (Rho-en) is conjugated with the magnetic core-shell Fe₃O₄@SiO₂ NPs has been strategically designed and synthesized. The final product was characterized by X-ray power diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectra (FTIR) and UV-visible absorption and fluorescence emission. Fluorescence and UV-visible spectra results showed that the resultant multifunctional nanoparticles Rho-Fe₃O₄@SiO₂ exhibited selective ‘turn-on’ type fluorescent enhancements and distinct color changes with Hg²⁺. The selectivity of the Rho-Fe₃O₄@SiO₂ for Hg(II) ion is better than that of the Rho-en in the same conditions. In addition, the presence of magnetic Fe₃O₄ nanoparticles in the sensor Rho-Fe₃O₄@SiO₂ NPs would also facilitate the magnetic separation of the Hg(II)-Rho-Fe₃O₄@SiO₂ from the solution.     

Synthesis and emission analysis of RE (Eu or Dy):Li2TiO3 ceramics

The development and photoluminescence analysis of Eu³⁺or Dy³⁺ ions in the matrix of lithium titanate (Li₂TiO₃) ceramics by using a solid state reaction method are reported. Emission spectra of Eu³⁺:Li₂TiO₃ ceramics have shown strong red emission at 611 nm (⁵D₀ → ⁷F₂) with λ_exci = 392 nm (⁷F₀ → ⁵L₆) and from the Dy³⁺:Li₂TiO₃, a blue emission at 493 nm (⁴F_9/2 → ⁶H_15/2) and also an yellow emission at 582 nm (⁴F_9/2 → ⁶H_13/2) have been observed with λ_exci = 366 nm (⁶H_15/2 → ⁶P_5/2). Both the rare-earth ions containing ceramics have displayed their brighter emission performance from their measured spectral results. In addition, X-ray diffraction (XRD), Fourier transform infra red (FTIR) spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX) have been used to characterize the structural properties of (Eu³⁺ or Dy³⁺):Li₂TiO₃ ceramics.     

Cerium Containing Al- and Zr-Pillared Clays: Promoting Effect of Cerium (III) Ions on Structural and Catalytic Properties

Ce³⁺ containing Al- and Zr-pillared clays were prepared by co-hydrolysis and co-intercalation methods, respectively. The materials were characterized by XRD, IR and near IR techniques. The expansion in the clay lattice as a result of pillaring was confirmed from X-ray diffraction study. The basal spacing for the pillared clay materials was observed typically in the range of 18–23 Å. The IR and near IR studies were employed to show the presence of acidic and non-acidic hydroxyl groups in the pillared clays. The IR peak at 3630 cm⁻¹ corresponding to the structural hydroxyl groups was more intense in pillared clays than in the parent clay. This peak is retained even after calcination at 500^∘C. Various overtone and combination bands were observed in the NIR range of 1200–2500 nm for the pillared clay materials. Pillaring with Al- and Zr-inorganic polycations enhanced the catalytic activity of the parent clays for dehydration of cyclohexanol. The presence of Ce³⁺ ions in the pillared clays was found to influence catalytic activity and stability of the Brønsted acidic sites. The stabilizing effect of cerium ion in the pillared clays is attributed to the competitive site occupancy and prevention of octahedral migration of the catalytically active protons.     

Evidence for Dual Activation of IK(M) and IK(Ca) Caused by QO-58 (5-(2,6-Dichloro-5-fluoropyridin-3-yl)-3-phenyl-2-(trifluoromethyl)-1H-pyrazolol[1,5-a]pyrimidin-7-one)

QO-58 (5-(2,6-dichloro-5-fluoropyridin-3-yl)-3-phenyl-2-(trifluoromethyl)-1H-pyrazolol[1,5-a]pyrimidin-7-one) has been regarded to be an activator of K_V7 channels with analgesic properties. However, whether and how the presence of this compound can result in any modifications of other types of membrane ion channels in native cells are not thoroughly investigated. In this study, we investigated its perturbations on M-type K⁺ current (I_K(M)), Ca²⁺-activated K⁺ current (I_K(Ca)), large-conductance Ca²⁺-activated K⁺ (BK_Ca) channels, and erg-mediated K⁺ current (I_K(erg)) identified from pituitary tumor (GH₃) cells. Addition of QO-58 can increase the amplitude of I_K(M) and I_K(Ca) in a concentration-dependent fashion, with effective EC₅₀ of 3.1 and 4.2 μM, respectively. This compound could shift the activation curve of I_K(M) toward a leftward direction with being void of changes in the gating charge. The strength in voltage-dependent hysteresis (V_hys) of I_K(M) evoked by upright triangular ramp pulse (V_ramp) was enhanced by adding QO-58. The probabilities of M-type K⁺ (K_M) channels that will be open increased upon the exposure to QO-58, although no modification in single-channel conductance was seen. Furthermore, GH₃-cell exposure to QO-58 effectively increased the amplitude of I_K(Ca) as well as enhanced the activity of BK_Ca channels. Under inside-out configuration, QO-58, applied at the cytosolic leaflet of the channel, activated BK_Ca-channel activity, and its increase could be attenuated by further addition of verruculogen, but not by linopirdine (10 μM). The application of QO-58 could lead to a leftward shift in the activation curve of BK_Ca channels with neither change in the gating charge nor in single-channel conductance. Moreover, cell exposure of QO-58 (10 μM) resulted in a minor suppression of I_K(erg) amplitude in response to membrane hyperpolarization. The docking results also revealed that there are possible interactions of the QO-58 molecule with the KCNQ or K_Ca1.1 channel. Overall, dual activation of I_K(M) and I_K(Ca) caused by the presence of QO-58 eventually may have high impacts on the functional activity (e.g., anti-nociceptive effect) residing in electrically excitable cells. Care must be exercised when interpreting data generated with QO-58 as it is not entirely KCNQ/K_V7 selective.     

Hydroxyl radical-related electrogenerated chemiluminescence reaction for a ruthenium tris(2,2′)bipyridyl/co-reactants system at boron-doped diamond electrodes

An electrogenerated chemiluminescence (ECL) reaction of the Ru(bpy)₃²⁺ (2,2′-bipyridyl, bpy)/co-reactant system in the extremely high-potential region (over 2.6 V versus Ag/AgCl) was probed using a boron-doped diamond (BDD) electrode. At the BDD electrode, three ECL waves (1.25, 2.30 and 3.72 V) were observed in cyclic voltammograms for 20 mM ascorbic acid (AA). For the ECL peaks observed at 1.25 V corresponding to the oxidation potential for Ru(bpy)₃²⁺ (1.15 V), the light intensities and current densities were found to depend on the square root of the AA concentration. This suggests that AA oxidation, followed by the formation of the reducing radical that is necessary for generating the excited state of Ru(bpy)₃^2+* occurred through homogeneous electron-transfer between Ru(bpy)₃³⁺ and the AA species. However, for the ECL peaks at 2.30 V, the current densities and light intensities linearly increased with increasing AA concentration, suggesting that the reducing radical was formed through the direct oxidation at the electrode surface. The ECL reaction at 3.72 V was observed only at the BDD electrode and not at other electrodes. The onset potentials for the light intensity were approximately 2.6 V, independently of the type of the co-reactants (e.g. 2-propanol and AA). The peak potentials exhibited linear relation with the co-reactant concentration. In the analysis of the ECL intensity for various co-reactants (alcohols) that show different reactivity for the hydrogen abstraction reaction, the order of the light intensities at the peaks for alcohols was found to be consistent with that for the rate constants of the hydrogen abstraction reaction. These results indicate that the co-reactant radical was formed through the hydrogen abstraction reaction with the hydroxyl radical (HO) generated during the oxygen evolution reaction.     

Density Functional Study of the CO Oxidation on a Doped Rutile TiO2(110): Effect of Ionic Au in Catalysis

We used density functional theory to examine whether doping oxides makes them better oxidation catalysts. We studied in detail titania doped with Au and used CO oxidation as a test of the oxidizing power of the system. We show that doping with Au, Ag, Cu, Pt, Pd, Ni reduces dramatically the bond of surface oxygen to titania or ceria, making them better oxidation catalysts. These calculations suggest that it is worthwhile to explore doped oxides as oxidation catalysts.     

A fluorescent color/intensity changed chemosensor for Fe by photo-induced electron transfer (PET) inhibition of fluoranthene derivative

A fluorescent color/intensity changed fluoranthene derivative chemosensor for Fe³⁺ has been prepared and confirmed by ¹H-NMR, ¹³C-NMR, HRMS, and crystal data, which displays a high selectivity and antidisturbance for Fe³⁺ among environmentally and biologically relevant metal ions. Fluorescence studies show that fluorescent emission peak blue shifts about 100 nm with fluorescent intensity enhancing 75-fold, indicating a Fe³⁺-selective dual-emission behavior. Further study demonstrates the detection limit on fluorescence response of the sensor to Fe³⁺ is down to 10⁻⁷ M range. The fluorescence signals of chemosensor can be restored with o-phenanthroline, showing the binding of chemosensor and Fe³⁺ is really chemically reversible.     

Novel coated graphite electrode for the selective determination of Gd(III) in rocks and waste water samples

A novel gadolinium selective coated graphite electrode based on 2,6-bis-[1-{N-cyanopropyl,N-(2-methylpridyl)}aminoethyl]pyridine [P] is described. The best performance was exhibited by the electrode having membrane composition P:NaTPB:PVC:NPOE as 8:4:30:58 (%, w/w). The electrode demonstrates excellent potentiometric characteristics towards gadolinium ion over several interfering ions. The electrode exhibited a Nernstian response to Gd³⁺ ion over a wide concentration range 2.8 × 10⁻⁷ to 5.0 × 10⁻² M with a detection limit (6.3 ± 0.1) × 10⁻⁸ M and slope 19.6 ± 0.1 mV decade⁻¹ of a_Gd³⁺. Furthermore, it showed a fast response time (12 s) and can be used for 2.5 months without significant divergence in its characteristics. Noticeably, the electrode can tolerate the concentration of different surfactants up to 1.0 × 10⁻⁴ M and can be used successfully in 30% (v/v) ethanol media and 10% (v/v) methanol and acetonitrile water mixture. The useful pH range of this sensor is 2.0 to 8.0. It is sufficiently selective and can be used for the determination of Gd³⁺ ions in waste water and rock samples. It also serves as a good indicator in the potentiometric titration of GdCl₃ with EDTA.     

Oxidative coupling of methane over Ce4+-doped Ba3 WO6 catalysts: investigation on oxygen species responsible for catalytic performance

Ce⁴⁺ doped Ba₃ WO₆ complex oxides were used as catalysts for methane oxidative coupling (MOC), and characterized by XPS and O₂-TPD-MS techniques. The results indicate that the ratio of electrophilic oxygen species O^– and O ₂ ^– to lattice oxygen on the surface is crucial for C₂ selectivity. By adjusting the relative amount of cations in Ba-W-Ce complex oxides with perovskite superstructure interstitial oxygen species can be created which benefits C₂ selectivity by raising the relative amount of (O^– + O ₂ ^– ) on the surface.     

NO Reduction with CO in the Presence of O2 over Cu/Al2O3 (3) – Structural Analysis of Active Species by Means of XAFS and UV/VIS/NIR Spectroscopy

The local structure around Cu supported on Al₂O₃ was determined by UV/VIS/NIR and XAFS spectroscopic techniques. The relationship between catalytic performance for NO–CO–O₂ reaction and the state of supported Cu species is discussed. A new method for estimating the fraction of aggregated to isolated Cu species is proposed.     

The Evidence for Effective Inhibition of INa Produced by Mirogabalin ((1R,5S,6S)-6-(aminomethyl)-3-ethyl-bicyclo [3.2.0] hept-3-ene-6-acetic acid), a Known Blocker of CaV Channels

Mirogabalin (MGB, Tarlige^®), an inhibitor of the α₂δ-1 subunit of voltage-gated Ca²⁺ (Ca_V) channels, is used as a way to alleviate peripheral neuropathic pain and diabetic neuropathy. However, to what extent MGB modifies the magnitude, gating, and/or hysteresis of various types of plasmalemmal ionic currents remains largely unexplored. In pituitary tumor (GH₃) cells, we found that MGB was effective at suppressing the peak (transient, I_Na(T)) and sustained (late, I_Na(L)) components of the voltage-gated Na⁺ current (I_Na) in a concentration-dependent manner, with an effective IC₅₀ of 19.5 and 7.3 μM, respectively, while the K_D value calculated on the basis of minimum reaction scheme was 8.2 μM. The recovery of I_Na(T) inactivation slowed in the presence of MGB, although the overall current–voltage relation of I_Na(T) was unaltered; however, there was a leftward shift in the inactivation curve of the current. The magnitude of the window (I_Na(W)) or resurgent I_Na (I_Na(R)) evoked by the respective ascending or descending ramp pulse (V_ramp) was reduced during cell exposure to MGB. MGB-induced attenuation in I_Na(W) or I_Na(R) was reversed by the further addition of tefluthrin, a pyrethroid insecticide known to stimulate I_Na. MGB also effectively lessened the strength of voltage-dependent hysteresis of persistent I_Na in response to the isosceles triangular V_ramp. The cumulative inhibition of I_Na(T), evoked by pulse train stimulation, was enhanced in its presence. Taken together, in addition to the inhibition of Ca_V channels, the Na_V channel attenuation produced by MGB might have an impact in its analgesic effects occurring in vivo.     

Modified electrodes for probing the metal-reductase activity of metalloproteins: the reduction of iron(III) catalyzed by Desulfovibrio vulgaris Hildenborough cytochrome c3

Cytochromes c₃ are polyheme c-type cytochromes characterized by low redox potentials, that have been shown to develop metal-reductase activity. In this paper, different strategies are explored to immobilize one of them, Desulfovibrio vulgaris Hildenborough cytochrome c₃, a highly basic tetraheme cytochrome, including adsorption, covalent bonding, imprisonment in a layer-by-layer assembly, and entrapment within cast films or a dialysis membrane. The performance and efficiency of modified (carbon or gold) electrodes have been evaluated using electrochemical (cyclic and square-wave voltammetry, current-time curves) techniques in the presence of a soluble Fe(III) complex, ammonium Fe(III) citrate acting as the soluble substrate, and chosen as a model system. The advantages and drawbacks of each strategy are discussed with the view of further extension of environmental interest to more toxic metal contaminants.     

Theoretical and Kinetic Tools for Selecting Effective Antioxidants: Application to the Protection of Omega-3 Oils with Natural and Synthetic Phenols

Radical-scavenging antioxidants play crucial roles in the protection of unsaturated oils against autoxidation and, especially, edible oils rich in omega-3 because of their high sensitivity to oxygen. Two complementary tools are employed to select, among a large set of natural and synthetic phenols, the most promising antioxidants. On the one hand, density functional theory (DFT) calculations provide bond dissociation enthalpies (BDEs) of 70 natural (i.e., tocopherols, hydroxybenzoic and cinnamic acids, flavonoids, stilbenes, lignans, and coumarins) and synthetic (i.e., 2,6-di-tert-butyl-4-methylphenol (BHT), 3-tert-butyl-4-hydroxyanisol (BHA), and tert-butylhydroquinone (TBHQ)) phenols. These BDEs are discussed on the basis of structure–activity relationships with regard to their potential antioxidant activities. On the other hand, the kinetic rate constants and number of hydrogen atoms released per phenol molecule are measured by monitoring the reaction of phenols with 2,2-diphenyl-1-picrylhydrazyl (DPPH^•) radical. The comparison of the results obtained with these two complementary methods allows highlighting the most promising antioxidants. Finally, the antioxidant effectiveness of the best candidates is assessed by following the absorption of oxygen by methyl esters of linseed oil containing 0.5 mmol L⁻¹ of antioxidant and warmed at 90 °C under oxygen atmosphere. Under these conditions, some natural phenols namely epigallocatechin gallate, myricetin, rosmarinic and carnosic acids were found to be more effective antioxidants than α-tocopherol.     

La(1−x)SrxCo1−yFeyO3 perovskites prepared by sol–gel method: Characterization and relationships with catalytic properties for total oxidation of toluene

La_(1−x)Sr_xCo_(1−y)Fe_yO₃ samples have been prepared by sol–gel method using EDTA and citric acid as complexing agents. For the first time, Raman mappings were achieved on this type of samples especially to look for traces of Co₃O₄ that can be present as additional phase and not detect by XRD. The prepared samples were pure perovskites with good structural homogeneity. All these perovskites were very active for total oxidation of toluene above 200 °C. The ageing procedure used indicated good thermal stability of the samples. A strong improvement of catalytic properties was obtained substituting 30% of La³⁺ by Sr²⁺ cations and a slight additional improvement was observed substituting 20% of cobalt by iron. Hence, the optimized composition was La_0.7Sr_0.3Co_0.8Fe_0.2O₃. The samples were also characterized by BET measurements, SEM and XRD techniques. Iron oxidation states were determined by Mössbauer spectroscopy. Cobalt oxidation states and the amount of O⁻ electrophilic species were analyzed from XPS achieved after treatment without re-exposition to ambient air. Textural characterization revealed a strong increase in the specific surface area and a complete change of the shape of primary particles substituting La³⁺ by Sr²⁺. The strong lowering of the temperature at conversion 20% for the La_0.7Sr_0.3Co_(1−y)Fe_yO₃ samples can be explained by these changes. X photoelectron spectra obtained with our procedure evidenced very high amount of O⁻ electrophilic species for the La_0.7Sr_0.3Co_(1−y)Fe_yO₃ samples. These species able to activate hydrocarbons could be the active sites. The partial substitution of cobalt by iron has only a limited effect on the textural properties and the amount of O⁻ species. However, Raman spectroscopy revealed a strong dynamic structural distortion by Jahn–Teller effect and Mössbauer spectroscopy evidenced the presence of Fe⁴⁺ cations in the iron containing samples. These structural modifications could improve the reactivity of the active sites explaining the better specific activity rate of the La_0.7Sr_0.3Co_0.8Fe_0.2O₃ sample. Finally, an additional improvement of catalytic properties was obtained by the addition of 5% of cobalt cations in the solution of preparation. As evidenced by Raman mappings and TEM images, this method of preparation allowed to well-dispersed small Co₃O₄ particles that are very efficient for total oxidation of toluene with good thermal stability contrary to bulk Co₃O₄.     

Modifications of carbon for polymer composites and nanocomposites

The various forms of carbon used in composite preparation include mainly carbon-black, carbon nanotubes and nanofibers, graphite and fullerenes. This review presents a detailed literature survey on the various modifications of the carbon nanostructures for nanocomposite preparation focusing upon the works published in the last decade. The modifications of each form of carbon are considered, with a compilation of structure-property relationships of carbon-based polymer nanocomposites. Modifications in both bulk and surface modifications have been reviewed, with comparison of their mechanical, thermal, electrical and barrier properties. A synopsis of the applications of these advanced materials is presented, pointing out gaps to motivate potential research in this field.