Decomposition of Dissolved Methylene Blue in Water Using a Submerged Arc Between Titanium Electrodes

Low voltage, low energy submerged pulsed arcs between Ti electrodes with a pulse repetition rate of 100 Hz, energies of 2.6–192 mJ and durations of 10–40 μs, followed by aging in the dark, were used to decompose 10 mg/l methylene blue (MB) contamination in 40 ml aqueous solutions, with and without the addition of 0.5 % H₂O₂. The impact of the arc treatment on the MB removal ratio (C₀–C_ta)/C₀ was considered as a function of aging time t_a, where C₀ and C_ta are the MB concentrations initially and after t_a (the time needed to complete removal of MB after cessation of exposure of the arc). Particles eroded from the electrodes during the discharge enabled MB decomposition during aging. The particles were studied by XRD, XPS and Raman analysis, and titanium oxides and peroxides were found. MB decomposition during aging is explained by the formation of a surface layer of titanium peroxide that forms by the interaction of titanium dioxide with H₂O₂, which produce radicals which oxidize the MB. The 99.6 % MB removal yield (G_99.6 = 90 g/kWhr) of the submerged pulsed arc process with Ti electrodes and addition of 0.5 % H₂O₂ was more than 60 times larger than obtained at 50 % removal with other plasma methods.     

Density-Functional Theory Study on Neutral and Charged M n C2 (M = Fe, Co, Ni, Cu; n = 1–5) Clusters

The ground-state geometrical and electronic properties of neutral and charged M _n C₂ (M = Fe, Co, Ni, Cu; n = 1–5) clusters are systematically investigated by density-functional calculations. The growth evolution trends of neutral and charged Fe _n C₂, Co _n C₂, Ni _n C₂ and Cu _n C₂ (n = 1–5) clusters are all from lower to higher dimensionality, while it is special for Cu _n C ₂ ^± (n = 1–5) clusters which favor planer growth model. The space directional distributions of Co and Ni indicate stronger magnetic anisotropy than that in Cu atoms. Compare with experimental data (photoelectron spectroscopy), our results are in good agreement. The interaction strengths between metal and carbon atoms in TM–C (TM = Fe, Co, Ni) clusters are comparable and are obviously larger than that in Cu–C clusters, and this interaction strengths also decrease through the sequence: cation > neutral > anion, which may be crucial in exploring the differences in the growth mechanisms of metal–carbon nano-materials.     

Fullerene-based anodic stripping voltammetry for simultaneous determination of Hg(II), Cu(II), Pb(II) and Cd(II) in foodstuff

Various carbon nanomaterials for use in anodic stripping voltammetric analysis of Hg(II), Cu(II), Pb(II) and Cd(II) are screened. Graphene, carbon nanotubes, carbon nanofibers and fullerene (C₆₀), dispersed in chitosan (Chit) aqueous solution, are used to modify a glassy carbon electrode (GCE). The fullerene-chitosan modified GCE (C₆₀-Chit/GCE) displays superior performance in terms of simultaneous determination of the above ions. The electrodes and materials are characterized by electrochemical impedance spectroscopy, cyclic voltammetry, scanning electron microscopy, Raman spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The excellent performance of C₆₀-Chit/GCE is attributed to the good electrical conductivity, large surface area, strong adsorption affinity and unique crystalline structure of C₆₀. Using differential pulse anodic stripping voltammetry, the assay has the following features for Hg(II), Cu(II), Pb(II) and Cd(II), respectively: (a) Peak voltages of +0.14, ?0.11, ?0.58 and???0.82 V (vs SCE); (b) linear ranges extending from 0.01–6.0 μM, 0.05–6.0 μM, 0.005–6.0 μM and 0.5–9.0 μM; and (c), detection limits (3σ method) of 3 nM (0.6 ppb), 14 nM (0.9 ppb), 1 nM (0.2 ppb) and 21 nM (2.4 ppb). Moreover, the modified GCE is well reproducible and suitable for long-term usage. The method was successfully applied to the simultaneous determination of these ions in spiked foodstuff.

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Graphical abstract Compared with graphene, carbon nanotubes and carbon nanofibers, an electrode modified with fullerene in chitosan electrode displays superior performance for the simultaneous anodic stripping voltammetric detection of Hg(II), Cu(II), Pb(II) and Cd(II).

     

Chemical composition of marine sediments in the Pacific Ocean from Sinaloa to Jalisco, Mexico

Marine sediments from Mexico’s West coast in the Pacific Ocean from Sinaloa to Jalisco were analyzed by energy-dispersive X-ray fluorescence technique. Ten sediment samples were collected in May, 2010 between 55.5 and 1264 m water depth with a Reinneck type box nucleate sampler. Sediments were dried and fractioned by granulometry. Their physical and chemical properties were determined in laboratory by standard methods, pH, and conductivity. Concentration and distribution of K, Ca, Ti Mn, Fe, Cu, Zn, Ga, Pb, Br and Sr were analyzed. In order to determine the status of the elements, enrichment factors were calculated. Total, organic carbon and CaCO₃ were also determined. Scanning electron microscopy and X-ray diffraction show predominant groups of compounds. As quality-control method, Certified Reference Material was both processed and analyzed at even conditions. Enrichment factors for K, Ca, Ti, Mn Fe, Cu, Zn, Ga, Ni, and Sr show they are conservative elements having concentrations in the range of unpolluted sites giving a base data line for the sampling zone In spite of moderately enrichment factors <100 μm size and bulk fractions, first Pb concentration fraction was similar to those found in not influenced by anthropogenic activities sites nearby Mazatlan Harbor. Bulk fraction concentration (52–133 μg g^?1) and enrichment factor show the influence of anthropogenic sources with values between lowest effect level and a third part of 250 μg g^?1value, which is considered to have severe effect levels for aquatic life.     

Submerged Arc Breakdown of Methylene Blue in Aqueous Solutions

Low voltage, low energy submerged pulsed arcs between a pair of carbon or iron electrodes with a pulse repetition rate of 100?Hz, energies of 2.6?C192?mJ and durations of 20, 50 and 100???s were used to remove methylene blue (MB) contamination from 30?ml aqueous solutions. The MB concentration decreased exponentially with rates of 0.0006?C0.0143?s^?1 during processing with the carbon electrode pair. With the iron electrodes, the MB concentration initially decreased faster (0.030?s^?1) than with the carbon electrodes, but later saturated. However when microparticles produced with the iron electrodes were periodically filtered, the high removal rate was maintained. Under these conditions, the volume of water which can be treated per unit energy expenditure was much higher with the submerged arc than with other plasma processes. A kinetic model based on MB degradation by OH· radicals formed by the discharge was formulated. The higher initial MB removal rate with iron electrodes is explained by additional OH· production from Fenton??s reaction between Fe⁺⁺ and H₂O₂ produced by the discharge. This rate is maintained if the eroded iron particles are filtered, but if eroded iron particles accumulate, degradation slows down and stops, possibly because the iron particles catalytically decompose H₂O₂ and hence stops Fenton??s reaction, and either directly or via increased Fe⁺⁺ dissolved from the particles, scavenge the OH· radicals.     

Transition metal atom adsorptions on a boron nitride nanocage

We have applied density functional theory within B3LYP and M05 functionals to investigate the chemical functionalization of B₁₂N₁₂ nanocage with 3d transition metal (TM) atoms. Main focuses have been placed on configurations corresponding to the located minima of the adsorbates, corresponding adsorption energies, and the modified electronic properties of the cage. It was shown that there is linear correlation between the adsorption energies of the B3LYP and M05 as the results of M05 are higher than those of B3LYP, about 0.52 eV. Based on calculations, the most stable adsorption site is over the bond shared by a four- and a six-membered ring in the outer surface of cluster, in most cases. Based on the M05 results, the adsorption energies of the Sc, Ti, V, Co, and Fe are relatively high (>1.51 eV) and those of Mn, Ni, and Cu calculated to be in the range of 1.00–1.22 eV. The Cr atom forms a weak bond with a boron atom of the B₁₂N₁₂ cluster, while Zn atom cannot be chemically adsorbed. Charge transfer from metals to cluster ascertained that the B₁₂N₁₂ plays as an electron-trapping center. Inducing certain impurity states within the electron density of states, the TM adsorption significantly reduces the HOMO–LUMO gap of cluster, ranging from 32 to 79 %.     

Thermal analysis study on the grain refinement of Al–15Zn–2.5Mg–2.5Cu alloy

Computer-aided cooling curve analysis is a reliable method to characterize the solidification behavior of an alloy. In this study, the effect of Al–5Ti–1B grain refiner on the solidification path, microstructure and macrostructure of a new Al–Zn–Mg–Cu super high-strength aluminum alloy containing high amounts of zinc was investigated using thermal analysis technique. The grain size measurement showed that Al–5Ti–1B reduces the grain size from 1402 to 405 μm. Solidification parameters in the liquidus region were in a good accordance with microstructural results. The addition of 1 mass% of Al–5Ti–1B grain refiner decreased ΔT _N from 9.1 to 7.7 °C. It also diminished recalescence undercooling from 1.42 to 0.32 °C. The grain refinement also altered dendritic structure of the alloy from a coarse, elongated and non-uniform to a rosette and more uniform shape. Moreover, the grain refiner resulted in a more uniform distribution of eutectic structure between dendrite arms. Furthermore, the grain refinement enhanced fraction of solid at dendrite coherency point from 21 % for unrefined alloy to 25 % for the alloy containing 1 mass% Al–5Ti–1B. In the same trend, the addition of 1 mass% Al–5Ti–1B reduced the amounts of porosity from 2.3 to 1.8 %.     

Co-doping a metal (Cr,Mn, Fe,Co, Ni,Cu, and Zn) on Mn/ZSM-5 catalyst and its effect on the catalytic reduction of nitrogen oxides with ammonia

Selective catalytic reduction (SCR) of NO_x by NH₃ over a series of Mn–M/Z catalysts (M = Cr, Mn, Fe, Co, Ni, Cu, Zn, and Z = the ZSM-5 Zeolite) synthesized by wet impregnation method was investigated. Mn–Fe/Z, Mn–Co/Z, and Mn–Cu/Z catalysts exhibited approximately 100 % NO_x conversion over a wide temperature range (200–360 °C) in a defined atmospheric condition, which was noticeably greater than that of Mn–Cr/Z (340–360 °C). Furthermore, the effect of addition of second metal oxide species to the initial Mn/Z catalyst on the structure of catalysts was studied by several characterization techniques. BET measurements revealed high surface area and pore volume of the Mn–Cu/Z catalyst. In addition, the XRD and UV–Vis DR results showed that addition of co-doped metal oxide species improved the dispersion of metal ions and inhibited crystallization of metal oxides. UV–Vis studies also were in good accordance with DTA/TG results confirming the formation of cobalt oxide and copper oxide clusters in Mn–Co/Z and Mn–Cu/Z catalysts, respectively. The FTIR spectra of pyridine adsorption, in addition, suggested the Mn–Cu/Z catalyst contained the most Lewis acid sites leading to more NO_x adsorption capacity.     

Calorimetric studies of Ag–Sn–Cu dental amalgam alloy powders and their amalgams

The methods of directed crystallization and thermal analysis were used to construct the section Cu_0.19Fe_0.33S_0.48–Cu_0.31Fe_0.23S_0.46 of the liquid–solid diagram of the Cu–Fe–S system. Pyrrhotite solid solution (Fe, Cu)S_1±δ (Poss) and nonstoichiometric isocubanite Cu_1.1Fe_2.0S_3.0 (Icb*) form from melt (L) successively. Isocubanite forms at 970 °C by peritectic reaction L + Poss → Icb*. At 930 °C, peritectic reaction L + Icb* → Iss proceeds with formation of intermediate solid solution with average composition Cu_1.0Fe_1.2S_2.0 (Iss). On the basis of the results from this paper and earlier published works, we built a fragment of liquidus surface for the Cu–Fe–S system in the crystallization field of nonstoichiometric isocubanite and stoichiometric isocubanite CuFe₂S₃ (Icb).     

The investigation of methyl phenyl silicone resin/epoxy resin using epoxy-polysiloxane as compatibilizer

Styrene–butadiene rubber was subjected to long-term thermal aging treatment at 80 °C with aging period up to 180 days. The degradation kinetics of the aged sample was analyzed by thermogravimetric analysis. Multiple heating rate experiments were carried out in nonisothermal conditions and three isoconversional model-free methods (Friedman; Kissinger–Akahira–Sunose; Li and Tang methods) were employed. The results showed that the temperature for 5 % mass loss increased, whereas the maximum mass loss temperature decreased after aging. Activation energies (E _a) derived from the three methods were found to be dependent on conversion degree (α). E _a increased with increasing α in the whole range of conversion for samples aged for 0, 60, and 120 days, while the aged samples displayed higher E _a values. However, samples aged for 180 days showed declining E _a versus α. The changes on the degradation kinetics were associated with the modification on the chemical structure after thermal aging.     

Interaction Between Two Similar Plane Parallel Double Layers for (NH4)2Fe(SO4)2 or (NH4)2Cu(SO4)2 Type Complex Salt Electrolytes at Positive Surface Potential

Interaction energies between two similar plane parallel double layers for (NH₄)₂Fe(SO₄)₂ or (NH₄)₂Cu(SO₄)₂ type complex salt electrolytes at positive surface potential were expanded in a power series and accurate numeral results were given for 0.1 ≤ y _e  < y ₀ ≤ 20. The general expressions were given for the interaction energies of A _ν +B _ν′ +C_ν? type complex salt electrolytes at y > 0. The interaction energies for simple salts NaCl, CaCl₂, Na₂SO₄, FeCl₃, Na₃PO₄, Mg₃(PO₄)₂, Al₂(SO₄)₃, and complex salts (NH₄)₂Fe(SO₄)₂ or (NH₄)₂Cu(SO₄)₂ at y ₀ = 1 were compared. There was hardly difference between these simple salts and this complex salt for the interaction energies. The interaction energy for complex salt (NH₄)₂Fe(SO₄)₂ was close to that for simple salt Na₃PO₄.

Supplemental files are available for this article. Go to the publisher's online edition of the Journal of Dispersion Science and Technology to view the free supplemental file.     

Preparation and properties of polyethoxysilsesquioxane‐C60 hybrids

Free‐standing films of C₆₀‐polyethoxysiloxane hybrids were prepared, and their optical limiting properties were evaluated. Triethoxysilylated C₆₀, with a formula of H₃C₆₀[Si(OEt)₃]₃, was synthesized by the hydrolysilylation of C₆₀ with triethoxysilane in the presence of platinum catalyst. C₆₀‐polyethoxysiloxanes were prepared by a cohydrolytic polycondensation of triethoxysilylated C₆₀ with tetraethoxysilane in a molar ratio of Si/C₆₀ = 10–1000 under nitrogen flow. The molecular weight of C₆₀‐polyethoxysiloxane increased with a decrease of Si/C₆₀. Transparent and flexible free‐standing films were prepared by aging an ethanol solution of C₆₀‐polyethoxysiloxane at 80 °C for 6–8 days. The mechanical strength and Young's modulus increased with a decrease in Si/C₆₀. These free‐standing films showed an optical limiting property, for which the threshold value decreased from 1163 mJ/cm² (Si/C₆₀ = 1000) to 130 mJ/cm² (Si/C₆₀ = 10) with a decrease of Si/C₆₀. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3273–3279, 2007     

Determination of reference interval values for inorganic elements in whole blood samples of humans and laboratory animals by X-ray fluorescence spectrometry

Inorganic elements are responsible for essential bodily functions, such as osmotic regulation, cardiac frequency and contractibility, blood clotting and neuromuscular excitability. The determination of inorganic elements in corporeal fluids such as blood, serum, plasma and urine is used as a monitor for a part or the whole organism; their values, then, are compared with reference interval values. In this study, the energy dispersive X-ray fluorescence spectrometry (EDXRF), applying the Fundamental Parameters method, for the determination of inorganic elements in whole blood samples from humans and laboratory animals, was used. Peripheral blood samples were collected and, before coagulation, 100 μL of sample were deposited onto Whatman No. 41 filter paper and dried, using infrared spotlight. The reference interval values for healthy Brazilian population of Na were found to be 1,788–1,826 μg g^?1, of Mg 63–75 μg g^?1, of P 602–676 μg g^?1, of S 1,519–1,718 μg g^?1, of Cl 2,743–2,867 μg g^?1, of K 1,508–1,630 μg g^?1, of Ca 214–228 μg g^?1, of Fe 170–184 μg g^?1, of Cu 4–6 μg g^?1 and of Zn 1–3 μg g^?1. The reference interval values for golden hamster (Mesocricetus auratus) of Na were found to be 1,714–1,819 μg g^?1, Mg 51–79 μg g^?1, P 970–1,080 μg g^?1, S 1,231–1,739 μg g^?1, Cl 2,775–2,865 μg g^?1, of K 1,968–2,248 μg g^?1, of Ca 209–257 μg g^?1, of Fe 145–267 μg g^?1, of Cu 4–6 μg g^?1 and of Zn 3–5 μg g^?1. A comparative study between EDXRF and instrumental neutron activation analysis data was carried out and the results for both techniques are statistically equal (α = 0.05). The results contribute for the establishment of reference interval values for Na, Mg, P, S, Cl, K, Ca, Cu and Zn in the healthy Brazilian population and the referred laboratory animal species.     

The hapticity of octafluorocyclooctatetraene in its first-row mononuclear transition metal carbonyl complexes: effect of perfluorination

The iron tricarbonyl complex of octafluorocyclooctatetraene was synthesized by Hughes and co-workers and shown by X-ray crystallography to have a trihapto–monohapto structure (η^3,1-C₈F₈)Fe(CO)₃ in contrast to the tetrahapto structure (η⁴-C₈H₈)Fe(CO)₃ formed by the non-fluorinated cyclooctatetraene. This difference has stimulated a comprehensive density functional theoretical study of the octafluorocyclooctatetraene metal carbonyl complexes (C₈F₈)M(CO) _n (n = 4, 3, 2, 1 for M = Ti, V, Cr, Mn, and Fe; n = 3, 2, 1 for M = Co, Ni) for comparison with their hydrogen analogues (C₈H₈)M(CO) _n . In most such systems, the substitution of fluorine for hydrogen leads to relatively small changes in the preferred structures. However, for the iron carbonyl derivatives (C₈X₈)Fe(CO)₃ (X = H, F), the difference observed experimentally has been confirmed by theory with (η^3,1-C₈F₈)Fe(CO)₃ and (η⁴-C₈H₈)Fe(CO)₃ being the lowest energy structures by 4 and 14 kcal/mol, respectively. The ligand exchange reactions C₈H₈ + (C₈F₈)M(CO) _n  → C₈F₈ + (C₈H₈)M(CO) _n are predicted to be exothermic for almost all of the systems considered, with the (η^3,1-C₈X₈)Fe(CO)₃ system being the main exception. This suggests that the C₈F₈ ligand generally bonds more weakly to transition metals than the C₈H₈ ligand in accord with the electron-withdrawing effect of the ligand fluorine atoms.     

Investigation into the crystal structure of bis(pyridine)-bis(trichloroacetato) copper(II) and its electrophotochemical properties

A novel chained Cu(II) complex was synthesized from trichloroacetato copper(II) and pyridine in ethanol solvent, and characterized by elemental analysis and infrared (IR) spectroscopy. The special crystal structure of the Cu(II) complex was determined by X-ray single-crystal diffraction. The results indicate that a chained structure of the Cu(II) complex formed through intermolecular hydrogen bonds. Cu(CCl₃COO)₂(C₅H₅N)₂(H₂O) was monoclinic, with unit cell P21/c and cell parameters as follows: a = 14.389(3) Å, b = 7.1911(14) Å, c = 23.107(8) Å, V = 2,257.5(10) Å³, Z = 4, M _r = 564.51, D _c = 1.661 mg/m³, T = 293(2) K, F(000) = 1,124, μ(Mo K_α) = 1.704 mm^?1, R = 0.0984, and ωR = 0.2791. The electrochemical behavior of the Cu(II) complex on a glassy carbon working electrode determined by cyclic voltammetry showed the electrochemical activity of the title compound at 0.2 to ?0.3 V (versus SCE) in NH₃–NH₄Cl buffer solution (pH 9.2), and the redox peak current of the complex had a good linear relationship with the square root of the scan rate in the range 0.02–0.2 V/s.     

Optimized preparation and preliminary evaluation of [64Cu]–DOTA–trastuzumab for targeting ErbB2/Neu expression

Breast cancer radioimmunoscintigraphy targeting HER2/neu expression is a growing field of work in nuclear medicine research. Trastuzumab is a monoclonal antibody that binds with high affinity to HER2/neu, which is over expressed on breast and other tumors. Developing new tracers for the detection of this cancer is of great interest. In this study, trastuzumab was successively labeled with [⁶⁴Cu]CuCl₂ after conjugation with DOTA-NHS-ester. The conjugate was purified by molecular filtration, the average number of DOTA conjugated per mAb was calculated and total concentration was determined by spectrophotometric method. DOTA–trastuzumab was labeled with ⁶⁴Cu produced by ⁶⁸Zn(p,αn)⁶⁴Cu nuclear reaction (30 MeV protons at 180 μA). Radiochemical purity, integrity of protein after radiolabeling and immunoreactivity of radiolabeled mAb trastuzumab with HER2/neu antigen and SkBr3 cell line were performed by RIA. In vitro stability of radiolabeled mAb in human serum was determined by thin layer chromatography. In vitro internalization studies were performed with the SkBr3 cell line and the tissue biodistribution of the ⁶⁴Cu–DOTA–trastuzumab was evaluated in wild-type rat (90 ± 5.5 μCi, 2, 6, 12, 24 h p.i.). The radioimmunoconjugate was prepared with a radiochemical purity of higher than 96 ± 0.5 % (ITLC) and specific activity as high as 5.3 μCi/μg. The average number of chelators per antibody for the conjugate used in this study was 5.8/1. The sample was showed to have similar patterns of migration in the gel electrophoresis. The ⁶⁴Cu–DOTA–trastuzumab showed high immunoreactivity towards HER2/neu antigen and SkBr3 cell line. In vitro stability of the labeled product was found to be more than 94 % in PBS and 82 ± 0.5 % in human serum over 48 h. In vitro internalization studies of the ⁶⁴Cu–DOTA–trastuzumab showed that up to 11.5 % of the radioimmunoconjugate internalized after 10 h. The accumulation of the radiolabeled mAb in liver, skin, intestine, lung, spleen, kidney and other tissues demonstrates a similar pattern to the other radiolabeled anti-HER2 immunoconjugates. ⁶⁴Cu–DOTA–trastuzumab is a potential compound for molecular imaging of PET for diagnosis and treatment studies and follow-up of HER2 expression in oncology.     

Phytochemical components,total phenol and mineral contents and antioxidant activity of six major medicinal plants from Rayen,Iran

The aim of this work was to evaluate the phytochemical components, minerals, the antioxidant activity and total phenol contents of the essential oil from aerial parts of six major medicinal plants in Rayen, Iran. The plants included Ranunculus arvensis, Teucrium polium, Dracocephalum polychaetum, Kelussia odoratissima, Artemisia sieberi and Thymus kotschyanus. Total phenol content ranged from 0.03 to 0.158 mg/mL. A. sieberi showed the highest radical scavenging ability (IC₅₀ = 94 μg/mL). The amount of minerals ranged as follows: P (0.23–29%), K (1.08–4.76%), Ca (0.78–2.35%), Mg (0.24–0.94%), Cu (8.3–15 mg/kg), Cd (0.7–1.1 mg/kg), Pb (2–11.7 mg/kg) and Fe (250–1280 mg/kg). A total of 79 compounds were identified across all plants. The main components studied in the plants were l-perillaldehyde, biosol, carvacrol, 1,8-cineol, terpinyl acetate and 1,2,3,6,7,7 a-hexahydro-5 h-inden 5-one.     

A theoretical study of electrocatalytic ammonia synthesis on single metal atom/MXene

Electrocatalytic ammonia synthesis under mild conditions is an attractive and challenging process in the earth's nitrogen cycle, which requires efficient and stable catalysts to reduce the overpotential. The N₂ activation and reduction overpotential of different Ti₃C₂O₂-supported transition metal (TM) (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Ru, Rh, Pd, Ag, Cd, and Au) single-atom catalysts have been analyzed in terms of the Gibbs free energies calculated using the density functional theory (DFT). The end-on N₂ adsorption was more energetically favorable, and the negative free energies represented good N₂ activation performance, especially in the presence Fe/Ti₃C₂O₂ (?0.75 eV). The overpotentials of Fe/Ti₃C₂O₂, Co/Ti₃C₂O₂, Ru/Ti₃C₂O₂, and Rh/Ti₃C₂O₂ were 0.92, 0.89, 1.16, and 0.84 eV, respectively. The potential required for ammonia synthesis was different for different TMs and ranged from 0.68 to 2.33 eV. Two possible potential-limiting steps may be involved in the process: (i) hydrogenation of N₂ to *NNH and (ii) hydrogenation of *NH₂ to ammonia. These catalysts can change the reaction pathway and avoid the traditional N–N bond-breaking barrier. It also simplifies the understanding of the relationship between the Gibbs free energy and overpotential, which is a significant factor in the rational designing and large-scale screening of catalysts for the electrocatalytic ammonia synthesis.     

Chemical separation of enriched cadmium target from copper backing in cyclotron production of radioisotope 111In

A radiochemical purification procedure was developed for the separation of enriched cadmium (¹¹¹Cd and ¹¹²Cd) from natural copper that used as backing; and was based upon the chromatographic adsorption. The separation of copper from cadmium was studied in this work. The ions were selectively separated from aqueous solution. Ion-exchange chromatography was employed as a column (1.5 cm i.d. and 15 cm length) with AG1-X8 resin (chloride form, 100–200 mesh) and a flow rate of 1–2 ml/min throughout the separation. 6 M HCl media was used for the adsorption of Cd and Cu on the resin. Then, Cu was eluted by 2 M HCl and Cd by 100 ml 0.5 M HNO₃. The amount of Cu and Cd ions in the final solution (0.5 M HNO₃) were measured by pulse polarographic method and the concentration of Cu was found to be <0.1 ppm. The Cd was quantitatively recovered and the recovery yield from ion-exchange chromatography was greater than 96 %.     

Influence of Ti additions on the martensitic phase transformation and mechanical properties of Cu–Al–Ni shape memory alloys

The effect of Ti additions on the microstructure and mechanical properties of Cu–Al–Ni shape memory alloys (SMA) was studied by means of a differential scanning calorimeter, field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction (XRD), a tensile test, a hardness test, and a shape memory effect test. The experimental results show that the Ti additions have an effective influence on the phase transformation behavior through generating a new phase into the microstructure, which is known as X-phase and/or controlling the grain size. The results of the XRD confirmed that the X-phase is a combination of two compounds, AlNi₂Ti and Ti₃·3Al. Nevertheless, it was found that with 0.7 mass% of Ti, the best phase transformation temperatures and mechanical properties were obtained. These improvements were due to the highest existence of the X-phase into the alloy along with a noticeable decrement of grain size. The Ti additions to the Cu–Al–Ni SMA were found to increase the ductility from 1.65 to 3.2 %, corresponding with increasing the strain recovery by the shape memory effect from 50 to 100 %; in other words, a complete recovery occurred after Ti additions.