Rare earth metals for automotive exhaust catalysts

International Nuclear Information System (INIS)

Shinjoh, Hirohumi

2006-01-01

The usage of rare earth metals for automotive exhaust catalysts is demonstrated in this paper. Rare earth metals have been widely used in automotive catalysts. In particular, three-way catalysts require the use of ceria compounds as oxygen storage materials, and lanthana as both a stabilizer of alumina and a promoter. The application for diesel catalysts is also illustrated. Effects of inclusion of rare earth metals in automotive catalysts are discussed

Ethylenediaminetetraacetates of neodymium and alkaline earth metals

International Nuclear Information System (INIS)

Barinov, A.V.; Pechurova, L.I.; Martynenko, K.I.; Popov, K.I.; Spitsyn, V.I.

1977-01-01

The possibilities have been studied of the formation of polynuclear complexonates of alkaline-earth metals (Ca, Sr, and Ba) based on neodymium derivatives EDTA of the composition NdA - . By pH-metry, electron spectroscopy, and derivatography it has been shown that the structure of complexes M 2 (NdA) 2 (where M- Ca, Sr, or Ba; A- EDTA) in the solution is not polynuclear. Hydroxopolynuclear complexes do not form under conditions studied. The data obtained agree with an assumption about polynuclear structure of the solid complex Ca(NdA) 2 x17 H 2 O and gradual weakening of the polynuclear nature upon substitution of Ca 2+ with Sr 2+ and Ba 2+

Alkaline-earth metal bicarbonates as lixiviants for uranium (VI) under CO2 sparging

International Nuclear Information System (INIS)

Vaziri, F.; White, D.A.

1989-01-01

In recent years it has become apparent that uranium is significantly soluble in solutions of alkaline-earth metal bicarbonates -particularly those of magnesium and calcium. A system has been proposed by previous authors in which milled uranium ore is leached in a medium to which an oxidizing agent, the metal hydroxide and CO 2 are added. The alkaline-earth metal hydroxides are much more readily soluble in this medium than the corresponding carbonates. Magnesium and calcium bicarbonates are quite soluble in aqueous media at neutral or nearly neutral pH. The pH determines the relative quantities of bicarbonate and carbonate ions in the system. Even if the pH is quite low, small amounts of carbonate ion are present that can complex with the uranyl ion to produce anionic uranyl complexes. Both UO 2 (CO 3 ) 2 2- and UO 2 (CO 3 ) 3 4- complexes are known and both have a very high stability constant. Despite the appearance of several patents on the use of alkaline-earth metal ions in carbonate media as uranium lixiviants, little theoretical or experimental work on the system has been published. In view of the potential of these systems for cheap, large-scale dissolution of uranium the present contribution will discuss the theory behind this method and provide some experimental data to verify the theoretical treatment. (author)

The industry of metallic rare earths (R.E.)

International Nuclear Information System (INIS)

Poirier, P.

1979-01-01

The following subjects are discussed: rare earths resources (rare earths abondance and world reserves, main ores). Rare earths separation and purification (ionic exchange, solvent extraction). Metallic rare earths and their mixtures, metallothermic reduction of oxides or fluorides (Ca, Mg, Al, Si or rare earth metals), Co-reduction process for intermetallic compounds (SmCo 5 ). Industrial applications of metallic rare earths (traditional applications such as flints, nodular cast iron, steel refining, magnesium industrie, applications under development such as rare earths/cobalt magnets, LaNi 5 for hydrogen storage, special alloys (automotive post combustion), magnetostrictive alloys). Economical problems: rare earth are elements relatively abundant and often at easily accessible prices. However, this group of 15 elements are liable to certain economical restraints. It is difficult to crack ore for only one rare earth. Availability of one given rare earth must be associated with the other corresponding rare earths to absorb all the other rare earths in other applications. Rare-earth industry has a strong expanding rate. 20% per year average for 6 years with Rhone-Poulenc. Thanks to their exceptional, specific characteristics rare earths have a bright future particularly for their metals

Rare-earth metal transition metal borocarbide and nitridoborate superconductors

Energy Technology Data Exchange (ETDEWEB)

Niewa, Rainer; Shlyk, Larysa; Blaschkowski, Bjoern [Stuttgart Univ. (Germany). Inst. fuer Anorganische Chemie

2011-07-01

Few years after the discovery of superconductivity in high-T{sub c} cuprates, borocarbides and shortly after nitridoborates with reasonably high T{sub c}s up to about 23 K attracted considerable attention. Particularly for the rare-earth metal series with composition RNi{sub 2}[B{sub 2}C] it turned out, that several members exhibit superconductivity next to magnetic order with both T{sub c} above or below the magnetic ordering temperature. Therefore, these compounds have been regarded as ideal materials to study the interplay and coexistence of superconductivity and long range magnetic order, due to their comparably high ordering temperatures and similar magnetic and superconducting condensation energies. This review gathers information on the series RNi{sub 2}[B{sub 2}C] and isostructural compounds with different transition metals substituting Ni as well as related series like RM[BC], RM[BN], AM[BN] and R{sub 3}M{sub 2}[BN]{sub 2}N (all with R = rare-earth metal, A = alkaline-earth metal, M = transition metal) with special focus on synthesis, crystal structures and structural trends in correspondence to physical properties. (orig.)

Method for synthesizing metal bis(borano) hypophosphite complexes

Science.gov (United States)

Cordaro, Joseph G.

2013-06-18

The present invention describes the synthesis of a family of metal bis(borano) hypophosphite complexes. One procedure described in detail is the syntheses of complexes beginning from phosphorus trichloride and sodium borohydride. Temperature, solvent, concentration, and atmosphere are all critical to ensure product formation. In the case of sodium bis(borano) hypophosphite, hydrogen gas was evolved upon heating at temperatures above 150.degree. C. Included in this family of materials are the salts of the alkali metals Li, Na and K, and those of the alkaline earth metals Mg and Ca. Hydrogen storage materials are possible. In particular the lithium salt, Li[PH.sub.2(BH.sub.3).sub.2], theoretically would contain nearly 12 wt % hydrogen. Analytical data for product characterization and thermal properties are given.

Composite nanoparticles containing rare earth metal and methods of preparation thereof

Science.gov (United States)

Kandapallil, Binil Itty Ipe; Krishnan, Lakshmi; Johnson, Francis

2018-04-10

The present invention is directed to composite nanoparticles comprising a metal, a rare earth element, and, optionally, a complexing ligand. The invention is also directed to composite nanoparticles having a core-shell structure and to processes for preparation of composite nanoparticles of the invention.

Near-Earth asteroids: Metals occurrence, extraction, and fabrication

Science.gov (United States)

Westfall, Richard

Near-earth asteroids occur in three principle types of orbits: Amor, Apollo, and Aten. Amor asteroids make relatively close (within 0.3 AU) approaches to the earth's orbit, but do not actually overlap it. Apollo asteroids spend most of their time outside the earth's orbital path, but at some point of close approach to the sun, they cross the orbit of the earth. Aten asteroids are those whose orbits remain inside the earth's path for the majority of their time, with semi-major axes less than 0.1 AU. Near-earth orbit asteroids include: stones, stony-irons, irons, carbonaceous, and super-carbonaceous. Metals within these asteroids include: iron, nickel, cobalt, the platinum group, aluminum, titanium, and others. Focus is on the extraction of ferrous and platinum group metals from the stony-iron asteroids, and the iron asteroids. Extraction of the metal fraction can be accomplished through the use of tunnel-boring-machines (TBM) in the case of the stony-irons. The metals within the story-iron asteroids occur as dispersed granules, which can be separated from the stony fraction through magnetic and gaseous digestion separation techniques. The metal asteroids are processes by drilling and gaseous digestion or by gaseous digestion alone. Manufacturing of structures, housings, framing networks, pressure vessels, mirrors, and other products is accomplished through the chemical vapor deposition (CVD) of metal coating on advanced composites and on the inside of contour-defining inflatables (CDI). Metal coatings on advanced composites provide: resistance to degradation in the hostile environments of space; superior optical properties; superior heat dissipation; service as wear coatings; and service as evidential coatings. Metal coatings on the inside of CDI produce metal load-bearing products. Fibers such as graphite, kevlar, glass, ceramic, metal, etc., can be incorporated in the metal coatings on the inside of CDI producing metal matrix products which exhibit high strength

Alkali metal and alkali earth metal gadolinium halide scintillators

Science.gov (United States)

Bourret-Courchesne, Edith; Derenzo, Stephen E.; Parms, Shameka; Porter-Chapman, Yetta D.; Wiggins, Latoria K.

2016-08-02

The present invention provides for a composition comprising an inorganic scintillator comprising a gadolinium halide, optionally cerium-doped, having the formula A.sub.nGdX.sub.m:Ce; wherein A is nothing, an alkali metal, such as Li or Na, or an alkali earth metal, such as Ba; X is F, Br, Cl, or I; n is an integer from 1 to 2; m is an integer from 4 to 7; and the molar percent of cerium is 0% to 100%. The gadolinium halides or alkali earth metal gadolinium halides are scintillators and produce a bright luminescence upon irradiation by a suitable radiation.

Spectral and thermal behaviours of rare earth element complexes with 3,5-dimethoxybenzoic acid

Directory of Open Access Journals (Sweden)

JANUSZ CHRUŚCIEL

2003-10-01

Full Text Available The conditions for the formation of rare earth element 3,5-dimethytoxybenzoates were studied and their quantitative composition and solubilities in water at 293 K were determined. The complexes are anhydrous or hydrated salts and their solubilities are of the orders of 10-5 – 10-4 mol dm-3. Their FTIR, FIR and X-ray spectra were recorded. The compounds were also characterized by thermogravimetric studies in air and nitrogen atmospheres and by magnetic measurements. All complexes are crystalline compounds. The carboxylate group in these complexes is a bidentate, chelating ligand. On heating in air to 1173 K, the 3,5-dimethoxybenzoates of rare earth elements decompose in various ways. The hydrated complexes first dehydrate to form anhydrous salts which then decompose in air to the oxides of the respective metals while in nitrogen to mixtures of carbon and oxides of the respective metals. The complexes are more stable in air than in nitrogen.

Metallic complexes with glyphosate: a review; Complexos metalicos com o herbicida glifosato: revisao

Energy Technology Data Exchange (ETDEWEB)

Coutinho, Claudia F.B.; Mazo, Luiz Henrique [Sao Paulo Univ., Sao Carlos, SP (Brazil). Inst. de Quimica]. E-mail: claudiabreda@iqsc.usp.br

2005-11-15

We present studies involving metallic ions and the herbicide glyphosate. The metallic complexes of Cu(II), Zn(II), Mn(II), Ni(II), Cd(II), Pb(II), Cr(III), Fe(III), Co(III), ammonium, sodium, Ag(I), alkaline earth metals and of some lanthanides ions are described. The complexes are discussed in terms of their synthesis, identification, stability and structural properties, based on data from the current literature. (author)

Process for making rare earth metal chlorides

International Nuclear Information System (INIS)

Kruesi, P.R.

1981-01-01

An uncombined metal or a metal compound such as a sulfide, oxide, carbonate or sulfate is converted in a liquid salt bath to the corresponding metal chloride by reacting it with chlorine gas or a chlorine donor. The process applies to metals of groups 1b, 2a, 2b, 3a, 3b, 4a, 5a and 8 of the periodic table and to the rare earth metals. The chlorine donor may be ferric or sulfur chloride. The liquid fused salt bath is made up of chlorides of alkali metals, alkaline earth metals, ammonia, zinc and ferric iron. Because the formed metal chlorides are soluble in the liquid fused salt bath, they can be recovered by various conventional means

Rare earth metals, rare earth hydrides, and rare earth oxides as thin films

International Nuclear Information System (INIS)

Gasgnier, M.

1980-01-01

The review deals with pure rare earth materials such as rare earth metals, rare earth hydrides, and rare earth oxides as thin films. Several preparation techniques, control methods, and nature of possible contaminations of thin films are described. These films can now be produced in an extremely well-known state concerning chemical composition, structure and texture. Structural, electric, magnetic, and optical properties of thin films are studied and discussed in comparison with the bulk state. The greatest contamination of metallic rare earth thin films is caused by reaction with hydrogen or with water vapour. The compound with an f.c.c. structure is the dihydride LnH 2 (Ln = lanthanides). The oxygen contamination takes place after annealing at higher temperatures. Then there appears a compound with a b.c.c. structure which is the C-type sesquioxide C-Ln 2 O 3 . At room atmosphere dihydride light rare earth thin films are converted to hydroxide Ln(OH) 3 . For heavy rare earth thin films the oxinitride LnNsub(x)Osub(y) is observed. The LnO-type compound was never seen. The present review tries to set the stage anew for the investigations to be undertaken in the future especially through the new generations of electron microscopes

Rare-earth transition-metal intermetallics: Structure-bonding-property relationships

Energy Technology Data Exchange (ETDEWEB)

Han, M. K. [Iowa State Univ., Ames, IA (United States)

2006-01-01

The explorations of rare-earth, transition metal intermetallics have resulted in the synthesis and characterization, and electronic structure investigation, as well as understanding the structure-bonding property relationships. The work has presented the following results: (1) Understanding the relationship between compositions and properties in LaFe_13-xSi_x system: A detailed structural and theoretical investigation provided the understanding of the role of a third element on stabilizing the structure and controlling the transformation of cubic NaZn{sub 13}-type structures to the tetragonal derivative, as well as the relationship between the structures and properties. (2) Synthesis of new ternary rare-earth iron silicides Re_2-xFe₄Si_14-y and proposed superstructure: This compound offers complex structural challenges such as fractional occupancies and their ordering in superstructure. (3) Electronic structure calculation of FeSi₂: This shows that the metal-semiconductor phase transition depends on the structure. The mechanism of band gap opening is described in terms of bonding and structural distortion. This result shows that the electronic structure calculations are an essential tool for understanding the relationship between structure and chemical bonding in these compounds. (4) Synthesis of new ternary rare-earth Zinc aluminides Tb₃Zn_3.6Al_7.4: Partially ordered structure of Tb₃Zn_3.6Al_7.4 compound provides new insights into the formation, composition and structure of rare-earth transition-metal intermetallics. Electronic structure calculations attribute the observed composition to optimizing metal-metal bonding in the electronegative (Zn, Al) framework, while the specific ordering is strongly influenced by specific orbital interactions. (5) Synthesis of new structure type of Zn₃₉(Cr_xAl_1-x)₈₁

Rare-Earth Transition-Metal Intermetallics: Structure-bonding-Property Relationships

Energy Technology Data Exchange (ETDEWEB)

Han, Mi-Kyung [Iowa State Univ., Ames, IA (United States)

2006-01-01

Our explorations of rare-earth, transition metal intermetallics have resulted in the synthesis and characterization, and electronic structure investigation, as well as understanding the structure-bonding-property relationships. Our work has presented the following results: (1) Understanding the relationship between compositions and properties in LaFe_13-xSi_x system: A detailed structural and theoretical investigation provided the understanding of the role of a third element on stabilizing the structure and controlling the transformation of cubic NaZn₁₃-type structures to the tetragonal derivative, as well as the relationship between the structures and properties. (2) Synthesis of new ternary rare-earth iron silicides RE_2-xFe₄Si_14-y and proposed superstructure: This compound offers complex structural challenges such as fractional occupancies and their ordering in superstructure. (3) Electronic structure calculation of FeSi₂: This shows that the metal-semiconductor phase transition depends on the structure. The mechanism of band gap opening is described in terms of bonding and structural distortion. This result shows that the electronic structure calculations are an essential tool for understanding the relationship between structure and chemical bonding in these compounds. (4) Synthesis of new ternary rare-earth Zinc aluminides Tb₃Zn_3.6Al_7.4: Partially ordered structure of Tb_3.6Zn_13-xAl_7.4 compound provides new insights into the formation, composition and structure of rare-earth transition-metal intermetallics. Electronic structure calculations attribute the observed composition to optimizing metal-metal bonding in the electronegative (Zn, Al) framework, while the specific ordering is strongly influenced by specific orbital interactions. (5) Synthesis of new structure type of Zn₃₉(Cr_xAl_1-x

Dimeric Complexes of Tryptophan with M2+ Metal Ions

NARCIS (Netherlands)

Dunbar, R. C.; Steill, J. D.; Polfer, N. C.; Oomens, J.

2009-01-01

IRMPD spectroscopy using the FELIX free electron laser and a Fourier transform ICR mass spectrometer was used to characterize the structures of electrosprayed dimer complexes M(2+)Trp(2) of tryptophan with a series of eight doubly charged metal ions, including alkaline earths Ca, Sr, and Ba, and

Rare earth metal bis(silylamide) complexes bearing pyridyl-functionalized indenyl ligand: synthesis, structure and performance in the living polymerization of L-lactide and rac-lactide.

Science.gov (United States)

Wang, Yibin; Lei, Yinlin; Chi, Shuhui; Luo, Yunjie

2013-02-07

Amine elimination of rare earth tris(silylamide) complexes Ln[N(SiHMe(2))(2)](3)(THF)(2) (Ln = La, Sm, Er, Lu) with 1 equiv. of the pyridyl-functionalized indenyl ligand C(9)H(7)CMe(2)CH(2)C(5)H(4)N-α afforded a series of neutral mono-indenyl-ligated rare earth metal bis(silylamide) complexes (C(9)H(6)CMe(2)CH(2)C(5)H(4)N-α)Ln[N(SiHMe(2))(2)](2) (Ln = La (1), Sm (2), Er (3), Lu (4)) in 83-87% isolated yields. Reaction of La[N(SiHMe(2))(2)](3)(THF)(2) with 2 equivalents of C(9)H(7)CMe(2)CH(2)C(5)H(4)N-α provided the neutral bis(indenyl) lanthanum mono(silylamide) complex (C(9)H(6)CMe(2)CH(2)C(5)H(4)N-α)(2)LaN(SiHMe(2))(2) (5). These complexes were characterized by elemental analysis, FT-IR and NMR (except for 3 for the strong paramagnetic property of the central metal). X-ray single crystal structural diffraction showed that 1-4 are isostructural and the central metals are four-coordinated by one indenyl ring, one nitrogen atom from the pendant pyridyl group, and two amide groups to form a distorted tetrahedral geometry; while the central metal in 5 is five-coordinated by two indenyl rings, two nitrogen atoms from the pendant pyridyl groups, and one amide group to adopt a distorted pyramidal geometry, if the indenyl ring is regarded as occupying an independent vertex. The monoanionic pyridyl-functionalized indenyl ligand is bonded to the central metal in η(5)/κ(1) constrained geometry configuration (CGC) mode. 1-4 are highly active for the ring-opening polymerization of L-lactide and rac-lactide. In the presence of 2 equivalents of benzyl alcohol, 1 shows high activity toward L-lactide and rac-lactide in a living fashion.

Application of infrared spectroscopy for study of chemical bonds in complexes of rare earth nitrates with alkylammonium nitrates

International Nuclear Information System (INIS)

Klimov, V.D.; Chudinov, Eh.G.

1974-01-01

The IR absorption spectra for the tri-n-octylamine, methyl-di-n-octylamine, their nitrates and complexes with the rare element nitrates are obtained. The IR spectra analysis of the complexes has suggested that the degree of covalent character bond of a nitrate with a metal grows with the atomic number of the element. Based on the comparison of the obtained data with those available in literature for various rare-earth complexes a conclusion is made that the bond character of a metal with nitrate groups is influenced by all ligands constituting the inner coordinating sphere. As the donor capacity of a ligand grows the covalent character of the metal-nitrate bond is enhanced. The replacement of the outer-sphere cations (trioctylammonium or methyldioctylammonium) only slightly affects the bond character of a metal with the nitrate group. The distribution coefficients in the rare-earth series are shown to decrease as the electrostatic part in the metal-nitrate declines. The phenomenon is attributed to the competition between nitrate and water for the metal bond as concurrently with the intensification of metal-nitrate covalent bond in the organic phase the strength of metal hydrates in aqueous phase grows much faster. (author)

Effect of Rare Earth Metals on the Microstructure of Al-Si Based Alloys

Directory of Open Access Journals (Sweden)

Saleh A. Alkahtani

2016-01-01

Full Text Available The present study was performed on A356 alloy [Al-7 wt %Si 0.0.35 wt %Mg]. To that La and Ce were added individually or combined up to 1.5 wt % each. The results show that these rare earth elements affect only the alloy melting temperature with no marked change in the temperature of Al-Si eutectic precipitation. Additionally, rare earth metals have no modification effect up to 1.5 wt %. In addition, La and Ce tend to react with Sr leading to modification degradation. In order to achieve noticeable modification of eutectic Si particles, the concentration of rare earth metals should exceed 1.5 wt %, which simultaneously results in the precipitation of a fairly large volume fraction of insoluble intermetallics. The precipitation of these complex intermetallics is expected to have a negative effect on the alloy performance.

Heterobimetallic transition metal/rare earth metal bifunctional catalysis: a Cu/Sm/Schiff base complex for syn-selective catalytic asymmetric nitro-Mannich reaction.

Science.gov (United States)

Handa, Shinya; Gnanadesikan, Vijay; Matsunaga, Shigeki; Shibasaki, Masakatsu

2010-04-07

The full details of a catalytic asymmetric syn-selective nitro-Mannich reaction promoted by heterobimetallic Cu/Sm/dinucleating Schiff base complexes are described, demonstrating the effectiveness of the heterobimetallic transition metal/rare earth metal bifunctional catalysis. The first-generation system prepared from Cu(OAc)(2)/Sm(O-iPr)(3)/Schiff base 1a = 1:1:1 with an achiral phenol additive was partially successful for achieving the syn-selective catalytic asymmetric nitro-Mannich reaction. The substrate scope and limitations of the first-generation system remained problematic. After mechanistic studies on the catalyst prepared from Sm(O-iPr)(3), we reoptimized the catalyst preparation method, and a catalyst derived from Sm(5)O(O-iPr)(13) showed broader substrate generality as well as higher reactivity and stereoselectivity compared to Sm(O-iPr)(3). The optimal system with Sm(5)O(O-iPr)(13) was applicable to various aromatic, heteroaromatic, and isomerizable aliphatic N-Boc imines, giving products in 66-99% ee and syn/anti = >20:1-13:1. Catalytic asymmetric synthesis of nemonapride is also demonstrated using the catalyst derived from Sm(5)O(O-iPr)(13).

A molecular mechanics (MM3(96)) force field for metal-amide complexes

International Nuclear Information System (INIS)

Hay, B.P.; Clement, O.; Sandrone, G.; Dixon, D.A.

1998-01-01

A molecular mechanics (MM3(96)) force field is reported for modeling metal complexes of amides in which the amide is coordinated through oxygen. This model uses a points-on-a-sphere approach which involves the parameterization of the Msingle bondO stretch, the Msingle bondO double-bond C bend, and the Msingle bondO double-bond Csingle bondX (X = C, H, N) torsion interactions. Relationships between force field parameters and metal ion properties (charge, ionic radius, and electronegativity) are presented that allow the application of this model to a wide range of metal ions. The model satisfactorily reproduces the structures of over fifty amide complexes with the alkaline earths, transition metals, lanthanides, and actinides

Synthesis of rare-earth metal amides bearing an imidazolidine-bridged bis(phenolato) ligand and their application in the polymerization of L-lactide.

Science.gov (United States)

Zhang, Zhongjian; Xu, Xiaoping; Li, Wenyi; Yao, Yingming; Zhang, Yong; Shen, Qi; Luo, Yunjie

2009-07-06

A series of neutral rare-earth metal amides supported by an imidazolidine-bridged bis(phenolato) ligand were synthesized, and their catalytic activity for the polymerization of l-lactide was explored. The amine elimination reactions of Ln[N(TMS)(2)](3)(mu-Cl)Li(THF)(3) with H(2)[ONNO] {H(2)[ONNO] = 1,4-bis(2-hydroxy-3,5-di-tert-butyl-benzyl)-imidazolidine} in a 1:1 molar ratio in tetrahydrofuran (THF) gave the neutral rare-earth metal amides [ONNO]Ln[N(TMS)(2)](THF) [Ln = La (1), Pr (2), Nd (3), Sm (4), Yb (5), and Y (6)] in high isolated yields. All of these complexes are fully characterized. X-ray structural determination revealed that complexes 1-6 are isostructural and have a solvated monomeric structure. The coordination geometry around each of the rare-earth metal atoms can be best described as a distorted trigonal bipyramid. It was found that complexes 1-6 are efficient initiators for the ring-opening polymerization of l-lactide, and the ionic radii of the central metals have a significant effect on the catalytic activity. A further study revealed that these rare-earth metal amides can initiate l-lactide polymerization in a controlled manner in the presence of 1 equiv of isopropyl alcohol.

Rare-earth metal prices in the USA ca. 1960 to 1994

Science.gov (United States)

Hedrick, James B.

1997-01-01

Rare-earth metal prices were compiled from the late 1950s and early 1960s through 1994. Although commercial demand for rare-earth metals began in 1908, as the alloy mischmetal, commercial quantities of a wide range of individual rare-earth metals were not available until the late 1950s. The discovery of a large, high-grade rare-earth deposit at Mountain Pass. CA, USA, in 1949, was significant because it led to the production of commercial quantities or rare-earth elements that reduced prices and encouraged wider application of the materials. The availability of ore from Mountain Pass, and other large rare-earth deposits, especially those in Australia and China, has provided the world with abundant resources for rare-earth metal production. This availability, coupled with improved technology from Government and private-sector metallurgical research, has resulted in substantial decreases in rare-earth metal prices since the late 1950s and early 1960s. Price series for the individual rare-earth metals (except promethium) are quoted on a kilogram basis from the late 1950s and early 1960s through 1994. Prices are given in US dollars on an actual and constant dollar basis. Industrial and economic factors affecting prices during this time period are examined.

Validation of ion chromatography for the determination of transition metal ions along with alkali, alkaline earth metal elements for uranium oxide fuel

International Nuclear Information System (INIS)

Kelkar, Anoop; Prakash, Amrit; Afzal, Mohd.; Panakkal, J.P.

2009-02-01

The present report describes the use of Ion chromatography (IC) methods with spectrophotometric and direct conductivity detection for the determination of transition metal elements and alkali alkaline earth metal ions in UO 2 pellets. Transmet analytical column and Metrosep- cation 1-2 column were used for the separation of transition metal elements and alkali and alkaline earth metal elements respectively. Oxalic acid and mixture of pyridine 2,6-dicarboxylic acid (PDCA), Na 2 SO 4 and NaCl were used as mobile phase for the separation of transition metal ions and monitored after post - column reaction with 4,2-pyridylazo resorcinol (PAR) at 520nm spectrophotometrically. In the determination of alkali and alkaline earth metal ions the interference of transition metals are removed by complexing them with PDCA. Mixture of tartaric acid and PDCA employed in the separation of alkali and alkaline earth metal ions and monitored on direct conductivity detector. Mobile phase composition was optimised for the base line separation. Calibration plots of Fe 3+ , Cu 2+ , Ni 2+ , Co 2+ , Cd 2+ , Mn 2+ , Li + , Na + , K + , Mg 2+ , Ca 2+ and Sr 2+ were linear over a wide dynamic range with regression coefficient better than 0.999. Detection limit of above ions were between 5-30ppb. To prevent the overloading of the cation exchange column, uranium matrix was removed from UO 2 sample by solvent extraction with 30% TBP - TOPO/CCl 4 . Ten sintered UO2 pellets of same lot were analysed and R.S.D. ±10% was obtained. These methods were validated by analysis of ILCE standards of UO 2 . (author)

Conducting metal dithiolate complexes

DEFF Research Database (Denmark)

Underhill, A. E.; Ahmad, M. M.; Turner, D. J.

1985-01-01

Further work on the chemical composition of the one-dimensional metallic metal dithiolene complex Li-Pt(mnt) is reported. The electrical conduction and thermopower properties of the nickel and palladium complexes are reported and compared with those of the platinum compound......Further work on the chemical composition of the one-dimensional metallic metal dithiolene complex Li-Pt(mnt) is reported. The electrical conduction and thermopower properties of the nickel and palladium complexes are reported and compared with those of the platinum compound...

Multiheteromacrocycles that Complex Metal Ions. Sixth Progress Report, 1 May 1979-30 April 1980

Science.gov (United States)

Cram, D. J.

1980-01-15

Objective is to design synthesize, and evaluate cyclic and polycyclic host organic compounds for their abilities to complex and lipophilize guest metal ions, their complexes, and their clusters. Host organic compounds consist of strategically placed solvating, coordinating, and ion-pairing sites tied together by covalent bonds through hydrocarbon units around cavities shaped to be occupied by guest metal ions or by metal ions plus their ligands. Specificity in complexation is sought by matching the following properties of host and guest: cavity and metal ion sizes; geometric arrangements of binding sites; number of binding sites; character of binding sites; and valences. During this period, hemispherands based on an aryloxy or cyclic urea unit, spherands based on aryloxyl units only, and their complexes with alkali metals and alkaline earths were investigated. An attempt to separate {sup 6}Li and {sup 7}Li by gel permeation chromatography of lithiospherium chloride failed. (DLC)

Band gaps and photocurrent responses of two novel alkaline earth metal(II) complexes based on 4,5-di(4′-carboxylphenyl)benzene

Energy Technology Data Exchange (ETDEWEB)

Meng, Jiang Ping; Yan, Zhi Shuo; Long, Ji Ying [Department of Applied Chemistry, College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400030 (China); Gong, Yun, E-mail: gongyun7211@cqu.edu.cn [Department of Applied Chemistry, College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400030 (China); Lin, Jian Hua, E-mail: jhlin@pku.edu.cn [Department of Applied Chemistry, College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400030 (China); State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)

2017-01-15

By using a rigid dicarboxylate ligand, 4,5-di(4′-carboxylphenyl)benzene (H{sub 2}L), two complexes formulated as SrL(DMF)(H{sub 2}O)·(CH{sub 3}CN) (DMF=N,N′-dimethylformamide) (1) and BaL(H{sub 2}O){sub 2} (2) were solvothermally synthesized and structurally characterized by single-crystal X-ray diffraction. Complexes 1 and 2 display two-dimensional (2D) layer structures. The two complexes exhibit different electrochemical and photoelectrochemical properties. Their thermal stabilities, cyclic voltammograms, UV–vis absorption and diffuse reflectance spectra and photoluminescence properties have been investigated. The band structures, the total density of states (TDOS) and partial density of states (PDOS) of the two complexes were calculated by CASTEP program. Complex 2 exhibits much higher photocurrent density than complex 1. The Mott–Schottky plots reveal that complexes 1 and 2 both are p-type semiconductors, which are in agreement with their band structure calculations. - Graphical abstract: Two alkaline earth metal(II) complexes with 2D layer structures are p-type semiconductors, they possess different band structures and density of states. And the Ba(II) complex 2 exhibits much higher photocurrent density than the Sr(II) complex 1.

The recent development of efficient Earth-abundant transition-metal nanocatalysts.

Science.gov (United States)

Wang, Dong; Astruc, Didier

2017-02-06

Whereas noble metal compounds have long been central in catalysis, Earth-abundant metal-based catalysts have in the same time remained undeveloped. Yet the efficacy of Earth-abundant metal catalysts was already shown at the very beginning of the 20th century with the Fe-catalyzed Haber-Bosch process of ammonia synthesis and later in the Fischer-Tropsch reaction. Nanoscience has revolutionized the world of catalysis since it was observed that very small Au nanoparticles (NPs) and other noble metal NPs are extraordinarily efficient. Therefore the development of Earth-abundant metals NPs is more recent, but it has appeared necessary due to their "greenness". This review highlights catalysis by NPs of Earth-abundant transition metals that include Mn, Fe, Co, Ni, Cu, early transition metals (Ti, V, Cr, Zr, Nb and W) and their nanocomposites with emphasis on basic principles and literature reported during the last 5 years. A very large spectrum of catalytic reactions has been successfully disclosed, and catalysis has been examined for each metal starting with zero-valent metal NPs followed by oxides and other nanocomposites. The last section highlights the catalytic activities of bi- and trimetallic NPs. Indeed this later family is very promising and simultaneously benefits from increased stability, efficiency and selectivity, compared to monometallic NPs, due to synergistic substrate activation.

Ultrafast Transient Absorption Spectroscopy of Polymer-Based Organophotoredox Catalysts Mimicking Transition-Metal Complexes

Science.gov (United States)

Jamhawi, Abdelqader; Paul, Anam C.; Smith, Justin D.; Handa, Sachin; Liu, Jinjun

2017-06-01

Transition-metal complexes of rare earth metals including ruthenium and iridium are most commonly employed as visible-light photocatalysts. Despite their highly important and broad applications, they have many disadvantages including high cost associated with low abundance in earth crust, potential toxicity, requirement of specialized ligands for desired activity, and difficulty in recycling of metal contents as well as associated ligands. Polymer-based organophotoredox catalysts are promising alternatives and possess unique advantages such as easier synthesis from inexpensive starting material, longer excited state life time, broad range of activity, sustainability, and recyclability. In this research talk, time-resolved photoluminescence and femtosecond transient absorption (TA) spectroscopy measurements of three novel polymer-based organophotoredox catalysts will be presented. By our synthetic team, their catalytic activity has been proven in some highly valuable chemical transformations, that otherwise require transition metal complexes. Time-resolved spectroscopic investigations have demonstrated that photoinduced processes in these catalysts are similar to the transition metal complexes. Especially, intramolecular vibrational relaxation, internal conversion, and intersystem crossing from the S1 state to the T1 state all occur on a sub-picosecond timescale. The long lifetime of the T1 state ( 2-3 microsecond) renders these polymers potent oxidizing and reducing agents. A spectroscopic and kinetic model has been developed for global fitting of TA spectra in both the frequency and time domains. Implication of the current ultrafast spectroscopy studies of these novel molecules to their roles in photocatalysis will be discussed.

Extraction of rare earths from iron-rich rare earth deposits

OpenAIRE

Bisaka, K.; Thobadi, I.C.; Pawlik, C.

2017-01-01

Rare earth metals are classified as critical metals by the United Nations, as they have found wide application in the fabrication of magnets, particularly those used in green energy technologies which mitigate global warming. Processing of ores containing rare earth elements is complex, and differs according to the nature of each ore. In the conventional process, run of mine (ROM) ores are processed in a physical separation plant to produce a concentrate from which rare earth elements are ext...

Equilibrium and non-equilibrium extraction separation of rare earth metals in presence of diethylenetriaminepentaacetic acid in aqueous phase

International Nuclear Information System (INIS)

Azis, Abdul; Teramoto, Masaaki; Matsuyama, Hideto.

1995-01-01

Equilibrium and non-equilibrium extraction separations of rare earth metals were carried out in the presence of chelating agent in the aqueous phase. The separation systems of the rare earth metal mixtures used were Y/Dy, Y/Ho, Y/Er and Y/Tm, and the chelating agent and the extractant were diethylenetriaminepentaacetic acid (DTPA) and bis (2,4,4-trimethylpentyl) phosphinic acid (CYANEXR 272), respectively. For Y/Dy and Y/Ho systems, higher selectivities were obtained in equilibrium separation compared with those in non-equilibrium separation. On the other hand, the selectivities in non-equilibrium separation were higher for Y/Er and Y/Tm systems. In the separation condition suitable to each system, the addition of DTPA to the aqueous phase was found to be very effective for obtaining higher selectivities. The distribution ratios of the rare earth metals and the selectivities in the equilibrium separations obtained experimentally were thoroughly analyzed by considering various equilibria such as the extraction equilibrium and the complex formation equilibrium between rare earth metals and DTPA in the aqueous phase. Moreover, the extraction rates and the selectivities in the non-equilibrium separations were also analyzed by the extraction model considering the dissociation reactions of the rare earth metal-DTPA complexes in the aqueous stagnant layer. Based on these analyses, we presented an index which is useful for selecting the optimum operation mode. Using this index, we can predict that the selectivities under equilibrium conditions are higher than those under non-equilibrium conditions for Y/Dy and Y/Ho systems, while for Y/Er and Y/Tm systems, higher selectivities are obtained under non-equilibrium conditions. The experimental results were in agreement with predictions by this index. Further, the selectivities in various systems including other chelating agents and extractants were discussed based on this index. (J.P.N.)

Synthesis, characterization, antibacterial and antifungal studies of some transition and rare earth metal complexes of N-benzylidene-2-hydroxybenzohydrazide

Directory of Open Access Journals (Sweden)

T.K. Chondhekar

2011-12-01

Full Text Available The solid complexes of Cu(II, Co(II, Mn(II, La(III and Ce(III were prepared from bidentate Schiff base, N-benzylidene-2-hydroxybenzohydrazide. The Schiff base ligand was synthesized from 2-hyhdroxybenzohydrazide and benzaldehyde. These metal complexes were characterized by molar conductivity, magnetic susceptibility, thermal analysis, X-ray diffraction, FTIR, 1H-NMR, UV-Vis and mass spectroscopy. The analytical data of these metal complexes showed metal:ligand ratio of 1:2. The physico-chemical study supports the presence of square planar geometry around Cu(II and octahedral geometry around Mn(II, Co(II, La(III and Ce(III ions. The IR spectral data reveal that the ligand behaves as bidentate with ON donor atom sequence towards central metal ion. The molar conductance values of metal complexes suggest their non-electrolyte nature. The X-ray diffraction data suggest monoclinic crystal system for these complexes. Thermal behavior (TG/DTA and kinetic parameters calculated by Coats-Redfern method are suggestive of more ordered activated state in complex formation. The ligand and their metal complexes were screened for antibacterial activity against Staphylococcus aureus and Escherichia coli and fungicidal activity against Aspergillus niger and Trichoderma.

Novel synergism by complex ligands in solvent extraction of rare earth metals(III) with β-diketones

International Nuclear Information System (INIS)

Imura, H.; Ebisawa, M.; Kato, M.; Ohashi, K.

2006-01-01

The extraction of rare earth metals(III) (RE) with hexafluoroacetylacetone (Hhfa) and 2-thenoyltrifluoroacetone (Htta) was studied in the presence of some cobalt(III) chelates such as tris(acetylacetonato)cobalt(III), tris(4-isopropyltropolonato)cobalt(III), tris(8-quinolinolato)cobalt(III), tris(8-quinolinethiolato)cobalt(III), and tris(diethyldithiocarbamato)cobalt(III) in benzene or toluene. The synergistic enhancement of the extraction of RE, especially of lanthanum(III) was found in all the systems. Therefore, those cobalt(III) chelates act as synergists or complex ligands. The equilibrium analysis and IR spectroscopic study were performed to evaluate the present synergistic mechanism. It was found that the RE-β-diketone chelates form 1:1 adducts, i.e., binuclear complexes, with the cobalt(III) chelates in the organic phase. The formation constants (β s,1 ) were determined and compared with those reported previously. The spectroscopic studies demonstrated that adducts have two different structures with inner- and outer-sphere coordination. In the former the cobalt(III) chelate directly coordinated to the RE ion and displaced the coordinated water molecules. In the latter the hydrogen-bonding was formed between the coordinating oxygen or sulfur atoms of cobalt(III) chelate and hydrogen atoms of the coordinated water molecules in the RE-β-diketone chelate. The types of the adducts are mainly due to the steric factors of the RE-β-diketone chelates and the cobalt(III) chelates

Thermal expansion and magnetic properties of benzoquinone-bridged dinuclear rare-earth complexes.

Science.gov (United States)

Moilanen, Jani O; Mansikkamäki, Akseli; Lahtinen, Manu; Guo, Fu-Sheng; Kalenius, Elina; Layfield, Richard A; Chibotaru, Liviu F

2017-10-10

The synthesis and structural characterization of two benzoquinone-bridged dinuclear rare-earth complexes [BQ(MCl 2 ·THF 3 ) 2 ] (BQ = 2,5-bisoxide-1,4-benzoquinone; M = Y (1), Dy (2)) are described. Of these reported metal complexes, the dysprosium analogue 2 is the first discrete bridged dinuclear lanthanide complex in which both metal centres reside in pentagonal bipyramidal environments. Interestingly, both complexes undergo significant thermal expansion upon heating from 120 K to 293 K as illustrated by single-crystal X-ray and powder diffraction experiments. AC magnetic susceptibility measurements reveal that 2 does not show the slow relation of magnetization in zero dc field. The absent of single-molecule behaviour in 2 arises from the rotation of the principal magnetic axis as compared to the pseudo-C 5 axis of the pentagonal bipyramidal environment as suggested by ab initio calculations. The cyclic voltammetry and chemical reduction experiments demonstrated that complexes 1 and 2 can be reduced to radical species containing [BQ 3 ˙ - ]. This study establishes efficient synthetic strategy to make bridged redox-active multinuclear lanthanide complexes with a pentagonal bipyramidal coordination environment that are potential precursors for single-molecule magnets.

Alkaline earth metals

International Nuclear Information System (INIS)

Brown, Paul L.; Ekberg, Christian

2016-01-01

The beryllium ion has a relatively small ionic radius. As a consequence of this small size, its hydrolysis reactions begin to occur at a relatively low pH. To determine the stability and solubility constants, however, the Gibbs energy of the beryllium ion is required. In aqueous solution calcium, like the other alkaline earth metals, only exists as a divalent cation. The size of the alkaline earth cations increases with increasing atomic number, and the calcium ion is bigger than the magnesium ion. The hydrolysis of barium(II) is weaker than that of strontium(II) and also occurs in quite alkaline pH solutions, and similarly, only the species barium hydroxide has been detected. There is only a single experimental study on the hydrolysis of radium. As with the stability constant trend, it would be expected that the enthalpy of radium would be lower than that of barium due to the larger ionic radius.

Process optimization and kinetics for leaching of rare earth metals from the spent Ni-metal hydride batteries.

Science.gov (United States)

Meshram, Pratima; Pandey, B D; Mankhand, T R

2016-05-01

Nickel-metal hydride batteries (Ni-MH) contain not only the base metals, but valuable rare earth metals (REMs) viz. La, Sm, Nd, Pr and Ce as well. In view of the importance of resource recycling and assured supply of the contained metals in such wastes, the present study has focussed on the leaching of the rare earth metals from the spent Ni-MH batteries. The conditions for the leaching of REMs from the spent batteries were optimized as: 2M H2SO4, 348K temperature and 120min of time at a pulp density (PD) of 100g/L. Under this condition, the leaching of 98.1% Nd, 98.4% Sm, 95.5% Pr and 89.4% Ce was achieved. Besides the rare earth metals, more than 90% of base metals (Ni, Co, Mn and Zn) were also leached out in this condition. Kinetic data for the dissolution of all the rare earth metals showed the best fit to the chemical control shrinking core model. The leaching of metals followed the mechanism involving the chemical reaction proceeding on the surface of particles by the lixiviant, which was corroborated by the XRD phase analysis and SEM-EDS studies. The activation energy of 7.6, 6.3, 11.3 and 13.5kJ/mol was acquired for the leaching of neodymium, samarium, praseodymium and cerium, respectively in the temperature range 305-348K. From the leach liquor, the mixed rare earth metals were precipitated at pH∼1.8 and the precipitated REMs was analyzed by XRD and SEM studies to determine the phases and the morphological features. Copyright © 2015. Published by Elsevier Ltd.

High-temperature corrosion of metals in the salt and metallic melts containing rare earths

Science.gov (United States)

Karpov, V. V.; Abramov, A. V.; Zhilyakov, A. Yu.; Belikov, S. V.; Volkovich, V. A.; Polovov, I. B.; Rebrin, O. I.

2016-09-01

A complex of independent methods was employed to study the corrosion resistance of molybdenum, zirconium, tantalum and tungsten in chloride, chloride-fluoride and fluoride-oxide melts based on LiCl, CaCl2, NaCl- KCl, LiF, and containing rare earths. Tests were conducted for 30 h at 750-1050 °C. The metals showed excellent corrosion resistance in fused chlorides (the corrosion rates were below 0.0005 g/(m2 h). Despite the presence of chemically active fluoride ions in the chloride-fluoride melts, the metals studied also showed very low corrosion rates, except molybdenum, for which the rate of corrosion was 0,8 g/(m2 h). The corrosion resistance of tantalum was considerably reduced in the fluoride-oxide melts; the corrosion rate was over 1 g/(m2 h) corresponding to the 8-th grade of stability and placing tantalum to the group of "low stability" materials.

Iron corrosion inhibition by phosphonate complexes of rare earth metals

International Nuclear Information System (INIS)

Kuznetsov, Yu.I.; Raskol'nikov, A.F.; Starobinskaya, I.V.; Alekseev, V.N.

1993-01-01

Capability is shown of trivalent rare earth nitrilotrimethylphosphonates (R= Ce, Pr, Nd, Eu, Lu, Y) to retard steel corrosion in soft water due to the formation of slightly soluble hydroxides on steel surface. The protective film is produced as a result of electrophilic substitution of nascent iron cations for rare earth ions in near the surface layer. The introduction of rare earth cations into the protective film is ascertained by Auger spectroscopy in combination with the argon spraying. A quantitative interrelation between the protective effectiveness and solubility product of rare earth hydroxides is revealed

Standard entropy for borides of non-transition metals, rare-earth metals and actinides

International Nuclear Information System (INIS)

Borovikova, M.S.

1986-01-01

Using as initial data the most reliable values of standard entropy for 10 compounds, the entropies for 40 compounds of non-transition metals, rare-earth metals and actinides have been evaluated by the method of comparative calculation. Taking into account the features of boride structures, two methods, i.e. additive and proportional, have been selected for the entropy calculations. For the range of borides the entropies were calculated from the linear relation of the latter to the number of boron atoms in the boride. For borides of rare-earth metals allowance has been made for magnetic contributions in conformity with the multiplicity of the corresponding ions. Insignificant differences in the electronic contributions to the entropy for borides and metals have been neglected. For dodecaborides only the additive method has been used. This is specified by the most rigid network that provides the same contribution to compound entropy. (orig.)

Ground-state properties of rare-earth metals: an evaluation of density-functional theory

International Nuclear Information System (INIS)

Söderlind, Per; Turchi, P E A; Landa, A; Lordi, V

2014-01-01

The rare-earth metals have important technological applications due to their magnetic properties, but are scarce and expensive. Development of high-performance magnetic materials with less rare-earth content is desired, but theoretical modeling is hampered by complexities of the rare earths electronic structure. The existence of correlated (atomic-like) 4f electrons in the vicinity of the valence band makes any first-principles theory challenging. Here, we apply and evaluate the efficacy of density-functional theory for the series of lanthanides (rare earths), investigating the influence of the electron exchange and correlation functional, spin-orbit interaction, and orbital polarization. As a reference, the results are compared with those of the so-called ‘standard model’ of the lanthanides in which electrons are constrained to occupy 4f core states with no hybridization with the valence electrons. Some comparisons are also made with models designed for strong electron correlations. Our results suggest that spin–orbit coupling and orbital polarization are important, particularly for the magnitude of the magnetic moments, and that calculated equilibrium volumes, bulk moduli, and magnetic moments show correct trends overall. However, the precision of the calculated properties is not at the level of that found for simpler metals in the Periodic Table of Elements, and the electronic structures do not accurately reproduce x-ray photoemission spectra. (paper)

Distribution of Rare Earth Metals in Technogenic Wastes of Energy Enterprises (Results of the Laboratory Studies)

OpenAIRE

Alexandr Ivanovich Khanchuk; Aleksandr Alekseevich Yudakov; Mikhail Azaryevich Medkov; Leonid Nikolayevich Alekseyko; Andrey Vasilyevich Taskin; Sergey Igorevich Ivannikov

2016-01-01

The results of the research interaction between ash and slag samples from Vladivostok TPP’s landfills saturated with underburning and ammonium hydrodifluoride were given. It was found out that the reactions of the main components of a concentrate with NH4HF2 are flowing with creation of complex ammonium fluoro-metalate. It is shown that the distribution of REM (rare earth metals) between foam and heavier products is going during the flotation process of carbon-containing ash and slag samples ...

Nuclear orientation studies of rare-earth metals

International Nuclear Information System (INIS)

Krane, K.S.; Morgan, G.L.; Moses, J.D.

1981-01-01

The angular distributions of gamma rays from 166 sup(m)Ho and 160 Tb aligned at low temperatures in, respectively, Ho metal and Tb metal have been measured. Large hyperfine splittings, expected for the rare earths, have been deduced from the temperature dependence of the gamma ray anisotropies. Both samples show a macroscopic magnetic anisotropy which is not consistent with an interpretation in terms of a randomly oriented polycrystalline structure. (orig.)

40 CFR 721.4668 - Hydrated alkaline earth metal salts of metalloid oxyanions.

Science.gov (United States)

2010-07-01

... metalloid oxyanions. 721.4668 Section 721.4668 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.4668 Hydrated alkaline earth metal salts of metalloid oxyanions. (a... hydrated alkaline earth metal salts of metalloid oxyanions (PMN P-94-1557) is subject to reporting under...

Magnetism in rare-earth metals and rare-earth intermetallic compounds

International Nuclear Information System (INIS)

Johansson, B.; Nordstroem, L.; Eriksson, O.; Brooks, M.S.S.

1991-01-01

Some of out recent local spin density electronic structure calculations for a number of ferromagnetic rare-earth systems are reviewed. A simplified model of the level densities for rare-earth (R) transition metal (M) intermetallic compounds, R m M n , is used to describe in a simple way the main features of their basic electronic structure. Explicit calculations for LuFe 2 and RFe 2 (R=Gd-Yb) systems are presented, where a method to treat simultaneously the localized 4f and the conduction electron spin magnetism is introduced. Thereby it becomes possible to calculate the K RM exchange coupling constant. This method is also used to study theoretically the permanent magnet material Nd 2 Fe 14 B. The electronic structure of the anomalous ferromagnets CeFe 2 and CeCo 5 is discussed and an induced 4f itinerant magnetism is predicted. The γ-α transition in cerium metal is considered, and results from calculations including orbital polarization are presented, where a volume collapse of 10% is obtained. On one side of the transition the 4f electrons are calculated to be essentially non-bonding (localized) and on the other side they are found to contribute to the metallic bonding and this difference in behaviour gives rise to the volume collapse. Recent calculations by Wills, Eriksson and Boring for the crystal structure changes in cerium metal under high pressure are discussed. Their successful results imply an itinerant picture for the 4f electrons in α-cerium. Consequently this strongly supports the view that the γ-α phase transformation is caused by a Mott transition of the 4f electrons. (orig.)

Complex Metal Hydrides for hydrogen storage and solid-state ion conductors

DEFF Research Database (Denmark)

Payandeh GharibDoust, SeyedHosein

and electricity in batteries. However, both hydrogen and electricity must be stored in a very dense way to be useful, e.g. for mobile applications. Complex metal hydrides have high hydrogen density and have been studied during the past twenty years in hydrogen storage systems. Moreover, they have shown high ionic...... conductivities which promote their application as solid electrolytes in batteries. This dissertation presents the synthesis and characterization of a variety of complex metal hydrides and explores their hydrogen storage properties and ionic conductivity. Five halide free rare earth borohydrides RE(BH4)3, (RE...... = La, Ce, Pr, Nd, Er) have been synthesized, which pave the way for studying the polymorphic transition in these compounds, obtaining new bimetallic borohydrides and designing new reactive hydride composites with improved hydrogen storage capacities. Two novel polymorphs of Pr(BH4)3 are identified...

Comparative study of binary and ternary complexes of some rare earths

International Nuclear Information System (INIS)

Makhijani, S.D.; Sangal, S.P.

1978-01-01

Modified form of Irving and Rossotti's pH titration technique has been used to evaluate and compare the stability constants of the binary and ternary complexes of Sc(III), Y(III), La(III), Pr(III), Nd(III) and Sm(III) at 30 0 at an ionic strength of 0.2M NaClO 4 . For the study of ternary complexes, nitrilotriacetic acid has been used as a primary ligand and polyhydroxy phenols i.e. pyrocatechol (PYC), pyrogallol (PYG) and gallic acid (GA) as secondary ligands. The stability constants of the binary complexes were found to be more than those of the corresponding ternary complexes which can reasonably be explained on the basis of electrostatic force between primary complex (metal in the case of binary complex) and secondary ligand, and space available to accommodate the secondary ligand. The stability decreases with the increase in ionic radii, i.e. Sc(III)>Y(III)>Sm(III)>Nd(III)>Pr(III)>La(III). In terms of secondary ligand, it follows the order PYC>GA>PYG. Rare earths form only 1:1 binary complex, and 1:1:1 mixed ligand complex in all the cases. (author)

Rare-earth-metal nitridophosphates through high-pressure metathesis

International Nuclear Information System (INIS)

Kloss, Simon David; Schnick, Wolfgang

2015-01-01

Developing a synthetic method to target an broad spectrum of unknown phases can lead to fascinating discoveries. The preparation of the first rare-earth-metal nitridophosphate LiNdP_4N_8 is reported. High-pressure solid-state metathesis between LiPN_2 and NdF_3 was employed to yield a highly crystalline product. The in situ formed LiF is believed to act both as the thermodynamic driving force and as a flux to aiding single-crystal formation in dimensions suitable for crystal structure analysis. Magnetic properties stemming from Nd"3"+ ions were measured by SQUID magnetometry. LiNdP_4N_8 serves as a model system for the exploration of rare-earth-metal nitridophosphates that may even be expanded to transition metals. High-pressure metathesis enables the systematic study of these uncharted regions of nitride-based materials with unprecedented properties. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Molecular dynamics of liquid alkaline-earth metals near the melting ...

Indian Academy of Sciences (India)

computed the velocity autocorrelation function (VACF), its memory function and ... Since alkaline-earth metals are simple like metals, the main difficulty in the calcu- lation of ..... recall that the conventional binding energy can be written [23] as.

Separation of rare earth metal using micro solvent extraction system

International Nuclear Information System (INIS)

Nishihama, S.; Tajiri, Y.; Yoshizuka, K.

2005-01-01

A micro solvent extraction system for the separation of rare earth metals has been investigated. The micro flow channel was fabricated on a PMMA plate. Extraction equilibrium was quickly achieved, without any mechanical mixing. The solvent extraction results obtained for the Pr/Sm binary solutions revealed that both rare earth metals are firstly extracted together. Following, the Pr is extracted in the organic solution and Sm remains in the aqueous phase. The phase separation can be successively achieved by contriving the cross section of the flow channel

Synthesis and characterization of anionic rare-earth metal amides stabilized by phenoxy-amido ligands and their catalytic behavior for the polymerization of lactide.

Science.gov (United States)

Lu, Min; Yao, Yingming; Zhang, Yong; Shen, Qi

2010-10-28

A dianionic phenoxyamido ligand was the first to be used to stabilize organo-rare-earth metal amido complexes. Amine elimination reaction of Nd[N(TMS)(2)](3)(μ-Cl)Li(THF)(3) (TMS = SiMe(3)) with aminophenol [HNOH] {[HNOH] = N-p-methylphenyl(2-hydroxy-3,5-di-tert-butyl)benzylamine} in a 1 : 1 molar-ratio gave the anionic phenoxyamido neodymium amide [NO](2)Nd[N(TMS)(2)][Li(THF)](2) (2) in a low isolated yield. A further study revealed that the stoichiometric reactions of Ln[N(TMS)(2)](3)(μ-Cl)Li(THF)(3) with the lithium aminophenoxy [HNOLi(THF)](2) (1) in tetrahydrofuran (THF) gave the anionic rare-earth metal amido complexes [NO](2)Ln[N(TMS)(2)][Li(THF)](2) [Ln = Nd (2), Sm (3), Yb (4), Y (5)] in high isolated yields. All of these complexes are fully characterized. X-Ray structure determination revealed that complex 1 has a solvated dimeric structure, and complexes 2-5 are isostructural, and have solvated monomeric structures. Each of the rare-earth metal ions is coordinated by two oxygen atoms and two nitrogen atoms from two phenoxyamido ligands and one nitrogen atom from the N(TMS)(2) group to form a distorted trigonal bipyramidal geometry. Each of the lithium atoms in complexes 2-5 is coordinated with one oxygen atom and one nitrogen atom from two different phenoxyamido groups, and one oxygen atom from one THF molecule to form a trigonal planar geometry. Furthermore, the catalytic behavior of complexes 2-5 for the ring-opening polymerization of l-lactide was explored.

Equilibrium studies on mixed ligand complexes of some tripositive rare earth ions

International Nuclear Information System (INIS)

Vimal, Rashmi; Singh, Mamta; Ram Nayan

1996-01-01

Interaction of the rare earth ions, La 3+ , Ce 3+ , Pr 3+ , Nd 3+ , Sm 3+ and Eu 3+ with the pair of ligands 1-amino-2-naphthol-4-sulphonic acid (an, H 2 A) and o-aminophenol (ap, HB) have been studied in aqueous solution at 25 degC (μ=0.1 M KNO 3 /NaCl). Equilibrium constants of the reactions involving the formations of the mixed ligand species MAB, MA 2 B 2- , MB 2 A - (M = metal ion) and the binary complexes containing up to three ligand molecules have been evaluated from the pH-metric data, and coordinating behaviour of the ligands in the formation of the mixed ligand complexes has been discussed. (author). 10 refs., 1 tab., 1 fig

Coordination kinetics of different metal ions with the amidoximated polyacrylonitrile nanofibrous membranes and catalytic behaviors of their complexes

Energy Technology Data Exchange (ETDEWEB)

Li, Fu; Dong, Yong Chun; Kang, Wei Min; Cheng, Bowen; Qu, Xiang; Cui, Guixin [School of Textiles, Tianjin Polytechnic University, Tianjin (China)

2016-12-15

Two transition metal ions (Fe{sup 3+} and Cu{sup 2+}) and a rare earth metal ion (Ce{sup 3+}) were selected to coordinate with amidoximated polyacrylonitrile (PAN) nanofibrous membrane for preparing three metal modified PAN nanofibrous membrane complexes (M-AO-n-PANs, M = Fe, Cu, or Ce) as the heterogeneous Fenton catalysts for the dye degradation in water under visible irradiation. The coordination kinetics of three metal ions with modified PAN nanofibrous membranes was studied and the catalytic properties of the resulting complexes were also compared. The results indicated that increasing metal ion concentrations in solution or higher coordination temperature led to a significant increase in metal content, particularly in Fe and Cu contents of the complexes. Their coordination process could be described using Langmuir isotherm and pseudo-second-order kinetic equations. Moreover, Fe-AO-n-PAN had the best photocatalytic efficiency for the dye degradation in acidic medium, but a lower photocatalytic activity than Cu-AO-n-PAN in alkali medium.

Effect of alkaline earth metal and magnesium cations on cadmium extraction from chloride solutions by tributyl phosphate

International Nuclear Information System (INIS)

Prokuev, V.A.; Belousov, E.A.

1985-01-01

At 298 K thermodynamic constants of cadmium (2) extraction from chloride solutions of magnesium, calcium, strontium and barium by tributyl phosphate are calculated. It is established, that logarithm of the thermodynamic extraction constant is in a linear dependence from the change in the cation hydration enthalpy in agqueous solution. It is shown, that activity coefficient of neutral complex CdVCl 2 differs from one, and it is the higher the more stable the complex is in alkaline earth metal chloride solutions

Synthesis and physicochemical investigation of complexes of rare earth, alkaline earth elements and copper with some β-diketones

International Nuclear Information System (INIS)

Nichiporuk, R.V.; Pechurova, N.I.; Snezhko, N.I.; Martynenko, L.I.; Kaul', A.R.; Zanina, A.S.; Shergina, S.I.; Sokolov, I.E.

1991-01-01

Complexes of rare earth, alkaline earth elements and copper with 2-methoxy-2,6,6-trimethylheptanedion-3,5 as well as complexes of yttrium and barium with 2-methoxy-2,6-dimethylheptanedion-3,5 were synthesized. Prepared complexes were investigated by the methods of chemical, thermal, X-ray phase analyses, IR spectroscopy. Complex sublimation was studied at 10 -1 -10 -2 mm Hg. Complexes of rare earths and copper don't change their composition during sublimation, and sublimation of hydrated complexes of barium, strontium and calcium leads to formation of anhydrous complexes. All prepared complexes are able to transsublimate multiply and qualitatively without change of composition. All isolated complexes can be used for preparation of film oxide coatings by CVD method

Ion chromatography of transition metals: specific alteration of retention by complexation reactions in the mobile and on the stationary phase

International Nuclear Information System (INIS)

Baumgartner, S.

1992-05-01

Ion chromatography of mono- and bivalent cations was performed on a conventional cation exchanger. The pH influence of an ethylene-diamine/citrate eluent was significant for the retention of alkaline earth and transition metals, but negligible for alkali ions. This was dealt with from a mechanistic point of view. Mobile phase optimization allowed fast isocratic analysis of mono- and bivalent cations and the separation of the radionuclides Cs-137 and Sr-90. A newly synthesized stationary phase containing iminodiacetate (IDA) function was investigated for cation chromatography using ethylenediamine/citrate eluents, polyhydroxy acid and dipicolinic acid. The column's high selectivity for transition metal ions in comparison to alkali and alkaline earth metals may be governed by the choice of complexing ability and pH of the eluent. Applications verified by atomic absorption spectroscopy include alkaline earth metals in beverages and the determination of Co, Cd and Zn in solutions containing more than 10 14 -fold excess of Na and Mg, such as sea water

Biodegradation of metal citrate complexes and implications for toxic-metal mobility

International Nuclear Information System (INIS)

Francis, A.J.; Dodge, C.J.; Gillow, J.B.

1992-01-01

The presence of synthetic and naturally occurring chelating agents in nuclear and toxic-metal wastes is a major concern because of their potential to enhance mobilization of metal ions away from the disposal sites. Of particular interest is citric acid, which is present in low-level and transuranic radioactive wastes and in domestic and industrial wastes (as washing fluids, for instance), as well as being found naturally. Citrate ions form multidentate, stable complexes with a variety of toxic metals and radionuclides; but biodegradation of these complexes, precipitating the metal ions as insoluble hydroxides, oxides or other salts, may retard migration. Here we report a study of the biodegradation of citrate complexes of Ca, Fe(II), Fe(III), Cd, Cu, Ni, Pb and U. Several of these complexes were not readily degraded by bacteria, and the biodegradability depended on the chemical nature of the complex, not on the toxicity of the metal to the bacteria. This resistance to biodegradation implies that citrate complexation may play an important part in migration of these hazardous wastes. (author)

Structurally triggered metal-insulator transition in rare-earth nickelates.

Science.gov (United States)

Mercy, Alain; Bieder, Jordan; Íñiguez, Jorge; Ghosez, Philippe

2017-11-22

Rare-earth nickelates form an intriguing series of correlated perovskite oxides. Apart from LaNiO 3 , they exhibit on cooling a sharp metal-insulator electronic phase transition, a concurrent structural phase transition, and a magnetic phase transition toward an unusual antiferromagnetic spin order. Appealing for various applications, full exploitation of these compounds is still hampered by the lack of global understanding of the interplay between their electronic, structural, and magnetic properties. Here we show from first-principles calculations that the metal-insulator transition of nickelates arises from the softening of an oxygen-breathing distortion, structurally triggered by oxygen-octahedra rotation motions. The origin of such a rare triggered mechanism is traced back in their electronic and magnetic properties, providing a united picture. We further develop a Landau model accounting for the metal-insulator transition evolution in terms of the rare-earth cations and rationalizing how to tune this transition by acting on oxygen rotation motions.

Synthesis and structure of alkaline earth and rare earth metal doped C70

International Nuclear Information System (INIS)

Takenobu, Taishi; Iwasa, Yoshihiro; Ito, Takayoshi; Mitani, Tadaoki

2001-01-01

We have investigated the structure sequence of alkaline earth (A=Ba, Sr) and rare earth metal (R=Eu) doped C 70 binary system. X-ray diffraction measurements revealed that there exist at least four stable phases at x=3, 4, 6, and 9 in A x C 70 and two stable phases at x=3, and 9 in R x C 70 . Among them, structural models are presented for Ba 4 C 70 , Sr 3 C 70 , and Eu 3 C 70 . Ba 4 C 70 takes an analogous structure to orthorhombic Ba 4 C 60 . Sr 3 C 70 and Eu 3 C 70 have monoclinic cell and their diffraction patterns are quite similar to that of Sm 3 C 70 , which involves a unique C 70 -metal-C 70 dimer structure. Preliminary results of Raman spectroscopy and magnetization measurement suggest the highly reduction state for A 9 C 70 and ferromagnetic interaction for Eu x C 70

Oligocyclopentadienyl transition metal complexes

Energy Technology Data Exchange (ETDEWEB)

de Azevedo, Cristina G.; Vollhardt, K. Peter C.

2002-01-18

Synthesis, characterization, and reactivity studies of oligocyclopentadienyl transition metal complexes, namely those of fulvalene, tercyclopentadienyl, quatercyclopentadienyl, and pentacyclopentadienyl(cyclopentadienyl) are the subject of this account. Thermal-, photo-, and redox chemistries of homo- and heteropolynuclear complexes are described.

Corrosion resistance of chromium-nickel steel containing rare earths

International Nuclear Information System (INIS)

Asatiani, G.N.; Mandzhgaladze, S.N.; Tavadze, L.F.; Chuvatina, S.N.; Saginadze, D.I.

1983-01-01

Effect of additional out-of-furnace treatment with complex alloy (foundry alloy) calcite-silicon-magnesium-rare earth metal on corrosion resistance of the 03Kh18N20M3D3C3B steel has been studied. It is shown that introduction of low additions of rare earths improves its corrosion resistance improves its corrosion resistance in agressive media (in 70% - sulfuric acid) in the range of transition from active to passive state. Effect of additional introduction of rare earth metals is not considerable, if potential of steel corrosion is in the range of stable passive state (32% - sulfuric acid). Additional out-of-furnace treatment with complex foundry alloy, containing rare earth metals, provides a possibility to use a steel with a lower content of Cr, Ni, Mo, than in conventional acid-resistant steels in highly agressive media

Enhancement in extraction rates by addition of organic acids to aqueous phase in solvent extraction of rare earth metals in presence of diethylenetriaminepentaacetic acid

International Nuclear Information System (INIS)

Matsuyama, Hideto; Azis, A.; Fujita, Mamoru; Teramoto, Masaaki.

1996-01-01

It is well known that the selectivity of rare earth metals by solvent extraction is increased by the addition of a chelating agent such as diethylenetriaminepentaacetic acid (DTPA) in the aqueous phase. One of the disadvantages of this method is the decrease in extraction rates due to complexation in the aqueous phase. In this paper, further addition of organic acids to the aqueous phase was examined for the purpose of enhancing the extraction rates in solvent extraction with DTPA. The addition of several kind of organic acids such as formic acid, acetic acid, malonic acid, lactic acid and citric acid was investigated for a Er/Y separation system. A remarkable enhancement in extraction rates was observed with a slight decrease in the selectivity by the addition of citric acid or lactic acid. Extraction rates in the presence of both DTPA and citric acid increased with the increase in citric acid concentration and with the increase in proton concentration. A 150 times enhancement in extraction rates was found in the low proton concentration condition. In order to analyze the extraction rates and selectivities obtained, mass transfer equations were presented by considering both the dissociation reaction of rare earth metal-DTPA complexes and the complex formation between rare earth metal and organic acid in the aqueous phase. The experimental data were analyzed by these equations. (author)

Separation of alkali and alkaline earth metals by polyethers using extraction chromatography

International Nuclear Information System (INIS)

Smulek, W.; Lada, W.A.

1979-01-01

The separation of alkali and alkaline earth metals by means of an acyclic polyether, 1,13-bis(8-chinolinyl)-1, 4, 7, 10, 13-pentaoxatridecane (CPOD), and cyclic polyethers, benzo-15-crown-5 (BC), dibenzo-18-crown-6 (DBC) and dicyclohexyl-18-crown-6 (DCHC), using extraction chromatography has been studied. The alkali metals can be effectively separated using SCN - as the accompanying ion. For alkaline earth metals, the best results were obtained with ClO 4 - ions. Different elution sequences for these groups were observed using chloroform and/meen=/ sitylene as diluents for the polyethers. (author)

Development of electrolytic process in molten salt media for light rare-earth metals production. The metallic cerium electrodeposition

International Nuclear Information System (INIS)

Restivo, T.A.G.

1994-01-01

The development of molten salt process and the respective equipment aiming rare-earth metals recovery was described. In the present case, the liquid cerium metal electrodeposition in a molten electrolytes of cerium chloride and an equimolar mixture of sodium and potassium chlorides in temperatures near 800 C was studied. Due the high chemical reactivity of the rare-earth metals in the liquid state and their molten halides, an electrolytic cell was constructed with controlled atmosphere, graphite crucibles and anodes and a tungsten cathode. The electrolytic process variables and characteristics were evaluated upon the current efficiency and metallic product purity. Based on this evaluations, were suggested some alterations on the electrolytic reactor design and upon the process parameters. (author). 90 refs, 37 figs, 20 tabs

Tetracyanidoborates with triply charged rare earth metal cations and their optical properties

International Nuclear Information System (INIS)

Hackbarth, Liisa

2015-01-01

The aim of this thesis is the description of the synthesis and characterization of a new group of tetracyanidoborates: tetracyanidoborates with trivalent rare earth metal cations. Their optical properties in the ultraviolet and visible range are also discussed. Common synthetic routes for tetracyanidoborates are adapted and applied to the preparation of the rare earth tetracyanidoborate hydrates. They are accessible with high yields and high purity through a reaction between the tetracyanidoboronic acid and rare earth hydroxides. It is shown that the rare earth tetracyanidoborates form isostructural groups, like the [LRE(H_2O)_5][B(CN)_4]_3.0.5 H_2O, where LRE"3"+ is La, Ce, Pr, Nd, Sm, Eu and Gd, the [HRE(H_2O)_7][B(CN)_4]_3 and the [HRE(H_2O)_8][B(CN)_4]_3.3 H_2O, where HRE"3"+ is Tb, Dy, Ho, Er, Tm, Yb, Lu and Y. Furthermore, the coordination number 9 is noticed to be common among the light rare earth cations, whereas the minor coordination number 8 is prevalent for the heavy rare earth cations in their tetracyanidoborates. This different construction of the coordination spheres between light and heavy rare earth cations leads to different structures depending on the energetic efficiency of the structural arrangement. Generally, the rare earth tetracyanidoborate hydrates are found to crystallize in the monoclinic crystal system. Moreover, other different crystal structures are observed depending on the crystallization temperature and the type of coordinated ligands and co-crystallized solvent molecules. The tetracyanidoborate hydrates with triply charged rare earth cations are characterized comprehensively by X-ray diffraction, vibrational spectroscopy, NMR-spectroscopy as well as by thermal analysis. Furthermore, the optical properties of some dehydrated rare earth tetracyanidoborates are investigated by UV-spectroscopy and luminescence measurements. The results of the optical measurements indicate that the tetracyanidoborates with rare earth metal cations

Experimental demonstration of efficient and selective population transfer and qubit distillation in a rare-earth-metal-ion-doped crystal

International Nuclear Information System (INIS)

Rippe, Lars; Nilsson, Mattias; Kroell, Stefan; Klieber, Robert; Suter, Dieter

2005-01-01

In optically controlled quantum computers it may be favorable to address different qubits using light with different frequencies, since the optical diffraction does not then limit the distance between qubits. Using qubits that are close to each other enables qubit-qubit interactions and gate operations that are strong and fast in comparison to qubit-environment interactions and decoherence rates. However, as qubits are addressed in frequency space, great care has to be taken when designing the laser pulses, so that they perform the desired operation on one qubit, without affecting other qubits. Complex hyperbolic secant pulses have theoretically been shown to be excellent for such frequency-addressed quantum computing [I. Roos and K. Molmer, Phys. Rev. A 69, 022321 (2004)] - e.g., for use in quantum computers based on optical interactions in rare-earth-metal-ion-doped crystals. The optical transition lines of the rare-earth-metal-ions are inhomogeneously broadened and therefore the frequency of the excitation pulses can be used to selectively address qubit ions that are spatially separated by a distance much less than a wavelength. Here, frequency-selective transfer of qubit ions between qubit states using complex hyperbolic secant pulses is experimentally demonstrated. Transfer efficiencies better than 90% were obtained. Using the complex hyperbolic secant pulses it was also possible to create two groups of ions, absorbing at specific frequencies, where 85% of the ions at one of the frequencies was shifted out of resonance with the field when ions in the other frequency group were excited. This procedure of selecting interacting ions, called qubit distillation, was carried out in preparation for two-qubit gate operations in the rare-earth-metal-ion-doped crystals. The techniques for frequency-selective state-to-state transfer developed here may be also useful also for other quantum optics and quantum information experiments in these long-coherence-time solid

Rare metal and rare earth pegmatites of Western India

International Nuclear Information System (INIS)

Maithani, P.B.; Nagar, R.K.

1999-01-01

Rajasthan Mica Belt in western India is one of the three major mica-producing Proterozoic pegmatite belts of India, the others being in Bihar and Andhra Pradesh. The pegmatites of these mica belts, in general, are associated with the rare metal (RM) and rare earth element (REE)-bearing minerals like columbite-tantalite, beryl, lepidolite and other multiple oxides. RM-REE pegmatites of Gujarat are devoid of commercially workable mica. These pegmatites are geologically characterised in this paper, based on their association with granite plutons geochemistry, and RM and REE potential. In addition to RM and RE-bearing pegmatites, granites of the Umedpur area, Gujarat also show anomalous concentration (0.97 wt%) of rare metals (6431 ppm Nb, 1266 ppm Ta, 454 ppm Sn, 173 ppm W), (1098 ppm Ce 1.36% Y 2 O 3 ) rare earths, and uranium (0.40% eU 3 O 8 ). Eluvial concentrations in the soil and panned concentrate (0.04-0.28 wt%) analysed up to 7.4%Nb 2 O 5 , 836 ppm Ta, and 1.31% Y. Discrete columbite-tantalite and betafite have been identified in these concentrates in addition to other minerals like zircon, rutile, sphene and xenotime. This area with discrete RM R EE mineral phases could be significant as a non-pegmatite source for rare metal and rare earths. (author)

Reactivity of monoolefin ligand in transition metal complexes

International Nuclear Information System (INIS)

Rybinskaya, M.I.

1978-01-01

The main tendencies in the coordinated olefin ligand property changes are discussed in the transition metal complexes in comparison with free olefins. The review includes the papers published from 1951 up to 1976. It has been shown that in complexes with transition metal cations olefin π-base acquires the ability to react with nucleophylic reagents. Olefin π-acids in complexes with zero valent metals are easily subjected to electrophylic reagent action. At coordination with transition metal cations the olefin properties are generally preserved, while in the zero-valent metal complexes the nonsaturated ligand acquires the properties of a saturated compounds. The ability of transition metal cations in complexes to intensify reactions of nucleophylic bimolecular substitution of vinyl halogen is clearly detected in contrast to the zero valent metal complexes. It has been shown that investigations of the coordinated olefin ligand reactivity give large possibilities in the further development of the organic synthesis. Some reactions are taken as the basis of important industrial processes

Viscosity measurements on metal melts at high pressure and viscosity calculations for the earth's core

International Nuclear Information System (INIS)

Mineev, Vladimir N; Funtikov, Aleksandr I

2004-01-01

A review is given of experimental and calculated data on the viscosity of iron-based melts on the melting curve. The interest in these data originates in the division of opinion on whether viscosity increases rather moderately or considerably in the high-pressure range. This disagreement is especially pronounced in the interpretation of the values of molten iron and its compounds in the environment of the earth's outer core. The conclusion on a substantial rise in viscosity mostly follows from the universal law, proposed by Brazhkin and Lyapin [1], of viscosity changing along the metal melting curve in the high-pressure range. The review analyzes available experimental and computational data, including the most recent ones. Data on viscosity of metals under shock wave compression in the megabar pressure range are also discussed. It is shown that data on viscosity of metal melts point to a small increase of viscosity on the melting curve. Specifics are discussed of the phase diagram of iron made more complex by the presence of several phase transitions and by the uncertainty in the position of the melting curve in the high-pressure range. Inaccuracies that arise in extrapolating the results of viscosity measurements to the pressure range corresponding to the earth's core environment are pointed out. (reviews of topical problems)

The importance of the Maillard-metal complexes and their silicates in astrobiology

Science.gov (United States)

Liesch, Patrick J.; Kolb, Vera M.

2007-09-01

The Maillard reaction occurs when sugars and amino acids are mixed together in the solid state or in the aqueous solution. Since both amino acids and sugar-like compounds are found on meteorites, we hypothesized that they would also undergo the Maillard reaction. Our recent work supports this idea. We have shown previously that the water-insoluble Maillard products have substantial similarities with the insoluble organic materials from the meteorites. The Maillard organic materials are also part of the desert varnish on Earth, which is a dark, shiny, hard rock coating that contains iron and manganese and is glazed in silicate. Rocks that are similar in appearance to the desert varnish have been observed on the Martian surface. They may also contain the organic materials. We have undertaken study of the interactions between the Maillard products, iron and other metals, and silicates, to elucidate the role of the Maillard products in the chemistry of desert varnish and meteorites. Specifically, we have synthesized a series of the Maillard-metal complexes, and have tested their reactivity towards silicates. We have studied the properties of these Maillard-metal-silicate products by the IR spectroscopy. The astrobiological potential of the Maillard-metal complexes is assessed.

Dependence of ultrasound attenuation in rare earth metals on ratio of grain size and wavelength

International Nuclear Information System (INIS)

Kanevskij, I.N.; Nisnevich, M.M.; Spasskaya, A.A.; Kaz'mina, V.I.

1978-01-01

Results of investigation of dependences of ultrasound attenuation coefficient α on the ratio of grain average size D and wavelength lambda are presented. The investigations were carried out on rare earth metal samples produced by arc remelting in a vacuum furnace. It is shown that the way of α dependence curves of D/lambda for each of the rare earth metal is determined only by the D. This fact permits to use ultrasound measurement for control average diameter of the rare earth metal grain

Alkali metals and group IIA metals

International Nuclear Information System (INIS)

Fenton, D.E.

1987-01-01

This chapter on the coordination complexes of the alkali metals of group IIA starts with a historical perspective of their chemistry, from simple monodentate ligands, metal-β-diketonates to the macrocyclic polyethers which act as ligands to the alkali and akaline earth metals. Other macrocyclic ligands include quarterenes, calixarenes, porphyrins, phthalocyanines and chlorophylls. A section on the naturally occurring ionophores and carboxylic ionophores is included. (UK)

When VSEPR fails: experimental and theoretical investigations of the behavior of alkaline-earth-metal acetylides.

Science.gov (United States)

Guino-o, Marites A; Alexander, Jacob S; McKee, Michael L; Hope, Håkon; Englich, Ulrich B; Ruhlandt-Senge, Karin

2009-11-09

The synthesis, structural, and spectral characterization as well as a theoretical study of a family of alkaline-earth-metal acetylides provides insights into synthetic access and the structural and bonding characteristics of this group of highly reactive compounds. Based on our earlier communication that reported unusual geometry for a family of triphenylsilyl-substituted alkaline-earth-metal acetylides, we herein present our studies on an expanded family of target derivatives, providing experimental and theoretical data to offer new insights into the intensively debated theme of structural chemistry in heavy alkaline-earth-metal chemistry.

CPA theory of the magnetization in rare earth transition metal alloys

International Nuclear Information System (INIS)

Szpunar, B.; Lindgaard, P.A.

1976-11-01

Calculations were made of the magnetic moment per atom of the transition metal and the rare earth metal in the intermetallic compounds, Gdsub(1-x)Nisub(x), Gdsub(1-x)Fesub(x), Gdsub(1-x)Cosub(x), and Ysub(1-x)Cosub(x). A simple model of the disordered alloy consisting of spins localized on the rare earth atoms and interacting with a narrow d-band is considered. The magnetic moment of the alloy at zero temperature is calculated within the molecular field and Hartree-Fock approximations. Disorder is treated in the coherent potential approximation. Results are in good agreement with the experimental data obtained for the crystalline and amorphous intermetallic compounds. It is shown that the temperature dependence of the magnetic moments and Curie and ferrimagnetic compensation temperatures can be accounted for by a simple model assuming a RKKY interaction between the rare-earth moments and the transition metal pseudo spin. The interaction is mediated by an effective alloy medium calculated using the CPA theory and elliptic densities of states. (Auth.)

Structural variations in layered alkaline earth metal cyclohexyl ...

Indian Academy of Sciences (India)

Administrator

because of the entrance of the guest molecules between the layers, there will be a change in the interlayer distance (Alberti 1978). Although M(IV) organo-phos- phonates are well documented, the chemistry of M(II) organophosphonates especially the alkaline earth metal organophosphonates has been explored marginally ...

Oxalate metal complexes in aerosol particles: implications for the hygroscopicity of oxalate-containing particles

Directory of Open Access Journals (Sweden)

T. Furukawa

2011-05-01

Full Text Available Atmospheric aerosols have both a direct and an indirect cooling effect that influences the radiative balance at the Earth's surface. It has been estimated that the degree of cooling is large enough to weaken the warming effect of carbon dioxide. Among the cooling factors, secondary organic aerosols (SOA play an important role in the solar radiation balance in the troposphere as SOA can act as cloud condensation nuclei (CCN and extend the lifespan of clouds because of their high hygroscopic and water soluble nature. Oxalic acid is an important component of SOA, and is produced via several formation pathways in the atmosphere. However, it is not certain whether oxalic acid exists as free oxalic acid or as metal oxalate complexes in aerosols, although there is a marked difference in their solubility in water and their hygroscopicity. We employed X-ray absorption fine structure spectroscopy to characterize the calcium (Ca and zinc (Zn in aerosols collected at Tsukuba in Japan. Size-fractionated aerosol samples were collected for this purpose using an impactor aerosol sampler. It was shown that 10–60% and 20–100% of the total Ca and Zn in the finer particles (<2.1 μm were present as Ca and Zn oxalate complexes, respectively. Oxalic acid is hygroscopic and can thus increase the CCN activity of aerosol particles, while complexes with various polyvalent metal ions such as Ca and Zn are not hygroscopic, which cannot contribute to the increase of the CCN activity of aerosols. Based on the concentrations of noncomplexed and metal-complexed oxalate species, we found that most of the oxalic acid is present as metal oxalate complexes in the aerosols, suggesting that oxalic acid does not always increase the hygroscopicity of aerosols in the atmosphere. Similar results are expected for other dicarboxylic acids, such as malonic and succinic acids. Thus, it is advisable that the cooling effect of organic aerosols should be estimated by including the

Lability of Nanoparticulate Metal Complexes at a Macroscopic Metal Responsive (Bio)interface

NARCIS (Netherlands)

Duval, Jérôme F.L.; Town, Raewyn M.; Leeuwen, Van Herman P.

2018-01-01

The lability of metal complexes expresses the extent of the dissociative contribution of the complex species to the flux of metal ions toward a macroscopic metal-responsive (bio)interface, for example, an electrodic sensor or an organism. While the case of molecular ligands is well-established, it

Coprecipitation of rare earths in systems of three heterovalent ions with sulfates of alkali and alkaline-earth metals

International Nuclear Information System (INIS)

Bobrik, V.M.

1977-01-01

Co-precipitation of rare earth elements (REE) in milligram amounts (3x10 -3 -3x10 -1 M) with alkali earth (AEE) sulfates in presence of alkali metal ions has been studied, the AEE:REE ratios between the co-precipitator and a REE (up to 50:1) the latter can be co-precipitated quantitatively in presence of corresponding alkali metals linked with the AEE in the Periodic table by a diagonal, i.e. in presence of sodium in co-precipitation with calcium sulfate, potassium with strontium sulfate and rubidium with barium sulfate. Co-precipitation with sulfates of sodium and calcium occurs at temperatures above 85 deg C and presumably involves calcium semihydrate. In presence of an alkali metal REE co-precipitation with AEE becomes isomorphic, i.e. at different AEE:REE ratios the co-precipitation coefficient remains constant. In presence of corresponding alkali metals the decrease in effectiveness of co-precipitation with AEE in the La-Lu series is more pronounced

Environmental Defects And Economic Impact On Global Market Of Rare Earth Metals

Science.gov (United States)

Charalampides, G.; Vatalis, K.; Karayannis, V.; Baklavaridis, A.

2016-11-01

Rare earth elements include the 14 lanthanides as well as lanthanium and often yttrium. Actually, most of them are not very rare and occur widely dispersed in a variety of rocks. Rare earth metals are vital to some of the world's faster growing industries: catalysts, Nd-magnets, ceramics, glass, metallurgy, battery alloys, electronics and phosphors. Worldwide, the main countries for distribution of rare earths deposits include China, USA, Russia, Brasil, India, Australia, Greenland and Malaysia. The mining and processing of rare earth metals usually result in significant environmental defects. Many deposits are associated with high concentrations of radioactive elements such as uranium and thorium, which requires separate treatment and disposal. The accumulation of rare earth elements in soils has occurred due to pollution caused by the exploitation of rare earth resources and the wide use of rare earths as fertilizers in agriculture. This accumulation has a toxic effect on the soil microfauna community. However, there are large differences in market prices due to the degree of purity determined by the specifications in the applications. The main focus of this article is to overview Rare Earth Metals’ overall impact on global economy and their environmental defects on soils during processing techniques and as they are used as fertilizers.

Selective extraction and recovery of rare earth metals from phosphor powders in waste fluorescent lamps using an ionic liquid system

International Nuclear Information System (INIS)

Yang, Fan; Kubota, Fukiko; Baba, Yuzo; Kamiya, Noriho; Goto, Masahiro

2013-01-01

Highlights: • Recycling of rare earth metals from fluorescent lamps was conducted by ionic liquid-mediated extraction. • Acid leaching from a waste phosphor powder was carried out using sulfuric and nitric acids. • An ionic liquid was used as extracting solvent for the rare earth metals. • Selective extraction of rare earth metals from leach solutions was attained. •The extracting ionic liquid phase was recyclable in the recovery process. -- Abstract: The recycling of rare earth metals from phosphor powders in waste fluorescent lamps by solvent extraction using ionic liquids was studied. Acid leaching of rare earth metals from the waste phosphor powder was examined first. Yttrium (Y) and europium (Eu) dissolved readily in the acid solution; however, the leaching of other rare earth metals required substantial energy input. Ionization of target rare earth metals from the waste phosphor powders into the leach solution was critical for their successful recovery. As a high temperature was required for the complete leaching of all rare earth metals, ionic liquids, for which vapor pressure is negligible, were used as an alternative extracting phase to the conventional organic diluent. An extractant, N, N-dioctyldiglycol amic acid (DODGAA), which was recently developed, showed a high affinity for rare earth metal ions in liquid–liquid extraction although a conventional commercial phosphonic extractant did not. An effective recovery of the rare earth metals, Y, Eu, La and Ce, from the metal impurities, Fe, Al and Zn, was achieved from the acidic leach solution of phosphor powders using an ionic liquid containing DODGAA as novel extractant system

Selective extraction and recovery of rare earth metals from phosphor powders in waste fluorescent lamps using an ionic liquid system

Energy Technology Data Exchange (ETDEWEB)

Yang, Fan; Kubota, Fukiko; Baba, Yuzo [Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Kamiya, Noriho [Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Center for Future Chemistry, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Goto, Masahiro, E-mail: m-goto@mail.cstm.kyushu-u.ac.jp [Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Center for Future Chemistry, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan)

2013-06-15

Highlights: • Recycling of rare earth metals from fluorescent lamps was conducted by ionic liquid-mediated extraction. • Acid leaching from a waste phosphor powder was carried out using sulfuric and nitric acids. • An ionic liquid was used as extracting solvent for the rare earth metals. • Selective extraction of rare earth metals from leach solutions was attained. •The extracting ionic liquid phase was recyclable in the recovery process. -- Abstract: The recycling of rare earth metals from phosphor powders in waste fluorescent lamps by solvent extraction using ionic liquids was studied. Acid leaching of rare earth metals from the waste phosphor powder was examined first. Yttrium (Y) and europium (Eu) dissolved readily in the acid solution; however, the leaching of other rare earth metals required substantial energy input. Ionization of target rare earth metals from the waste phosphor powders into the leach solution was critical for their successful recovery. As a high temperature was required for the complete leaching of all rare earth metals, ionic liquids, for which vapor pressure is negligible, were used as an alternative extracting phase to the conventional organic diluent. An extractant, N, N-dioctyldiglycol amic acid (DODGAA), which was recently developed, showed a high affinity for rare earth metal ions in liquid–liquid extraction although a conventional commercial phosphonic extractant did not. An effective recovery of the rare earth metals, Y, Eu, La and Ce, from the metal impurities, Fe, Al and Zn, was achieved from the acidic leach solution of phosphor powders using an ionic liquid containing DODGAA as novel extractant system.

Tetracyanidoborates with triply charged rare earth metal cations and their optical properties

Energy Technology Data Exchange (ETDEWEB)

Hackbarth, Liisa

2015-11-24

The aim of this thesis is the description of the synthesis and characterization of a new group of tetracyanidoborates: tetracyanidoborates with trivalent rare earth metal cations. Their optical properties in the ultraviolet and visible range are also discussed. Common synthetic routes for tetracyanidoborates are adapted and applied to the preparation of the rare earth tetracyanidoborate hydrates. They are accessible with high yields and high purity through a reaction between the tetracyanidoboronic acid and rare earth hydroxides. It is shown that the rare earth tetracyanidoborates form isostructural groups, like the [LRE(H{sub 2}O){sub 5}][B(CN){sub 4}]{sub 3}.0.5 H{sub 2}O, where LRE{sup 3+} is La, Ce, Pr, Nd, Sm, Eu and Gd, the [HRE(H{sub 2}O){sub 7}][B(CN){sub 4}]{sub 3} and the [HRE(H{sub 2}O){sub 8}][B(CN){sub 4}]{sub 3}.3 H{sub 2}O, where HRE{sup 3+} is Tb, Dy, Ho, Er, Tm, Yb, Lu and Y. Furthermore, the coordination number 9 is noticed to be common among the light rare earth cations, whereas the minor coordination number 8 is prevalent for the heavy rare earth cations in their tetracyanidoborates. This different construction of the coordination spheres between light and heavy rare earth cations leads to different structures depending on the energetic efficiency of the structural arrangement. Generally, the rare earth tetracyanidoborate hydrates are found to crystallize in the monoclinic crystal system. Moreover, other different crystal structures are observed depending on the crystallization temperature and the type of coordinated ligands and co-crystallized solvent molecules. The tetracyanidoborate hydrates with triply charged rare earth cations are characterized comprehensively by X-ray diffraction, vibrational spectroscopy, NMR-spectroscopy as well as by thermal analysis. Furthermore, the optical properties of some dehydrated rare earth tetracyanidoborates are investigated by UV-spectroscopy and luminescence measurements. The results of the optical

Chemistry and Properties of Complex Intermetallics from Metallic Fluxes

Energy Technology Data Exchange (ETDEWEB)

Kanatzidis, Mercouri G. [Northwestern Univ., Evanston, IL (United States)

2015-03-28

This project investigated the reaction chemistry and synthesis of new intermetallic materials with complex compositions and structures using metallic fluxes as solvents. It was found that the metallic fluxes offer several key advantages in facilitating the formation and crystal growth of new materials. The fluxes mostly explored were liquid aluminum, gallium and indium. The main purpose of this project was to exploit the potential of metallic fluxes as high temperature solvent for materials discovery in the broad class of intermetallics. This work opened new paths to compound formation. We discovered many new Si (or Ge)-based compounds with novel structures, bonding and physicochemical properties. We created new insights about the reaction chemistry that is responsible for stabilizing the new materials. We also studied the structural and compositional relationships to understand their properties. We investigated the use of Group-13 metals Al, Ga and In as solvents and have generated a wide variety of new results including several new ternary and quaternary materials with fascinating structures and properties as well as new insights as to how these systems are stabilized in the fluxes. The project focused on reactions of metals from the rare earth element family in combination with transition metals with Si and Ge. For example molten gallium has serves both as a reactive and non-reactive solvent in the preparation and crystallization of intermetallics in the system RE/M/Ga/Ge(Si). Molten indium behaves similarly in that it too is an excellent reaction medium, but it gives compounds that are different from those obtained from gallium. Some of the new phase identified in the aluminide class are complex phases and may be present in many advanced Al-matrix alloys. Such phases play a key role in determining (either beneficially or detrimentally) the mechanical properties of advanced Al-matrix alloys. This project enhanced our basic knowledge of the solid state chemistry

Rare earth element lithogeochemistry of granitoid mineral deposits

Energy Technology Data Exchange (ETDEWEB)

Taylor, R.P.; Fryer, B.J. (Memorial Univ. of Newfoundland, St. John' s (Canada). Dept. of Earth Sciences)

1983-12-01

As a monitor of the processes involved in the formation of granitoid mineral deposits the coherent group behaviour of the rare earth elements (REE) actively reflects changing fluid characteristics. For example, in the porphyry environment, magmatic-hydrothermal fluids produce potassic alteration with strong enrichment in the light rare earth elements, reflecting their high pH, low fluid/rock ratios, and the dominant role of Cl/sup -/ complexing in metal (i.e. Cu, Au) transport. With increasing fluid/rock ratios and decreasing pH accompanying the progressive involvement of meteoric fluids (and the production of propylitic, argillic, and phyllic alteration) anionic species such as F/sup -/ and CO/sub 3//sup 2 -/ become important in metal (e.g. Mo, W) transport through complexing, and their activity in the hydrothermal fluids is illustrated by mobilization of the heavy rare earth elements. The relative involvement of Cl/sup -/ versus F/sup -/ versus CO/sub 3//sup 2 -/ in metal transport in other granite-related systems can also be monitored through REE behaviour. Hence granitoid tin-tungsten mineralization and associated greisenization typically exhibit heavy rare earth enrichment and evidence the importance of F/sup -/ and CO/sub 3//sup 2 -/ in metal transport. Similarly, heavy rare earth element enrichment in hydrothermal uranium deposits can be related to the transport of uranium as carbonate complexes. REE are widely accepted as powerful tools in the study of rock petrogenesis, but their use has been neglected in the investigation of mineral deposits. The recognition of the systematic variation of REE distributions in granitoid mineral deposits suggests that the application of REE geochemistry, particularly when integrated with fluid inclusion and isotope studies, can provide l) an effective method for identifying the physiochemical controls of metal transport and 2) a useful criterion of elucidating metal distribution.

Rare earth element lithogeochemistry of granitoid mineral deposits

International Nuclear Information System (INIS)

Taylor, R.P.; Fryer, B.J.

1983-01-01

As a monitor of the processes involved in the formation of granitoid mineral deposits the coherent group behaviour of the rare earth elements (REE) actively reflects changing fluid characteristics. For example, in the porphyry environment, magmatic-hydrothermal fluids produce potassic alteration with strong enrichment in the light rare earth elements, reflecting their high pH, low fluid/rock ratios, and the dominant role of Cl - complexing in metal (i.e. Cu, Au) transport. With increasing fluid/rock ratios and decreasing pH accompanying the progressive involvement of meteoric fluids (and the production of propylitic, argillic, and phyllic alteration) anionic species such as F - and CO 3 2- become important in metal (e.g. Mo, W) transport through complexing, and their activity in the hydrothermal fluids is illustrated by mobilization of the heavy rare earth elements. The relative involvement of Cl - versus F - versus CO 3 2- in metal transport in other granite-related systems can also be monitored through REE behaviour. Hence granitoid tin-tungsten mineralization and associated greisenization typically exhibit heavy rare earth enrichment and evidence the importance of F - and CO 3 2- in metal transport. Similarly, heavy rare earth element enrichment in hydrothermal uranium deposits can be related to the transport of uranium as carbonate complexes. REE are widely accepted as powerful tools in the study of rock petrogenesis, but their use has been neglected in the investigation of mineral deposits. The recognition of the systematic variation of REE distributions in granitoid mineral deposits suggests that the application of REE geochemistry, particularly when integrated with fluid inclusion and isotope studies, can provide l) an effective method for identifying the physiochemical controls of metal transport and 2) a useful criterion of elucidating metal distribution

Calculation of binary phase diagrams between the actinide elements, rare earth elements, and transition metal elements

International Nuclear Information System (INIS)

Selle, J.E.

1992-01-01

Attempts were made to apply the Kaufman method of calculating binary phase diagrams to the calculation of binary phase diagrams between the rare earths, actinides, and the refractory transition metals. Difficulties were encountered in applying the method to the rare earths and actinides, and modifications were necessary to provide accurate representation of known diagrams. To calculate the interaction parameters for rare earth-rare earth diagrams, it was necessary to use the atomic volumes for each of the phases: liquid, body-centered cubic, hexagonal close-packed, and face-centered cubic. Determination of the atomic volumes of each of these phases for each element is discussed in detail. In some cases, empirical means were necessary. Results are presented on the calculation of rare earth-rare earth, rare earth-actinide, and actinide-actinide diagrams. For rare earth-refractory transition metal diagrams and actinide-refractory transition metal diagrams, empirical means were required to develop values for the enthalpy of vaporization for rare earth elements and values for the constant (C) required when intermediate phases are present. Results of using the values determined for each element are presented

Self-organization in metal complexes

International Nuclear Information System (INIS)

Radecka-Paryzek, W.

1999-01-01

Inorganic self-organization involves the spontaneous generation of well-defined supramolecular architectures from metal ions and organic ligands. The basic concept of supramolecular chemistry is a molecular recognition. When the substrate are metal ions, recognition is expressed in the stability and selectivity of metal ion complexation by organic ligands and depends on the geometry of the ligand and on their binding sites that it contains. The combination of the geometric features of the ligand units and the coordination geometries of the metal ions provides very efficient tool for the synthesis of novel, intriguing and highly sophisticated species such as catenanes, box structures, double and triple helicates with a variety of interesting properties. The article will focus on the examples of inorganic self-organization involving the templating as a first step for the assembly of supramolecular structures of high complexity. (author)

Student Learning of Complex Earth Systems: Conceptual Frameworks of Earth Systems and Instructional Design

Science.gov (United States)

Scherer, Hannah H.; Holder, Lauren; Herbert, Bruce

2017-01-01

Engaging students in authentic problem solving concerning environmental issues in near-surface complex Earth systems involves both developing student conceptualization of Earth as a system and applying that scientific knowledge using techniques that model those used by professionals. In this first paper of a two-part series, we review the state of…

Alkaline-earth metal phenylphosphonates and their intercalation chemistry

Czech Academy of Sciences Publication Activity Database

Melánová, Klára; Beneš, L.; Svoboda, J.; Zima, Vítězslav; Pospíšil, M.; Kovář, P.

2018-01-01

Roč. 47, č. 9 (2018), s. 2867-2880 ISSN 1477-9226 R&D Projects: GA ČR(CZ) GA17-10639S Institutional support: RVO:61389013 Keywords : intercalation * layered compounds * alkaline-earth metal phenylphosphonates Subject RIV: CA - Inorganic Chemistry OBOR OECD: Inorganic and nuclear chemistry Impact factor: 4.029, year: 2016

Chemoselective single-site Earth-abundant metal catalysts at metal–organic framework nodes

Energy Technology Data Exchange (ETDEWEB)

Manna, Kuntal; Ji, Pengfei; Lin, Zekai; Greene, Francis X.; Urban, Ania; Thacker, Nathan C.; Lin, Wenbin (UC)

2016-08-30

Earth-abundant metal catalysts are critically needed for sustainable chemical synthesis. Here we report a simple, cheap and effective strategy of producing novel earth-abundant metal catalysts at metal–organic framework (MOF) nodes for broad-scope organic transformations. The straightforward metalation of MOF secondary building units (SBUs) with cobalt and iron salts affords highly active and reusable single-site solid catalysts for a range of organic reactions, including chemoselective borylation, silylation and amination of benzylic C–H bonds, as well as hydrogenation and hydroboration of alkenes and ketones. Our structural, spectroscopic and kinetic studies suggest that chemoselective organic transformations occur on site-isolated, electron-deficient and coordinatively unsaturated metal centres at the SBUs via σ-bond metathesis pathways and as a result of the steric environment around the catalytic site. MOFs thus provide a novel platform for the development of highly active and affordable base metal catalysts for the sustainable synthesis of fine chemicals.

Synthesis, characterization and biological profile of metal and azo-metal complexes of embelin

Directory of Open Access Journals (Sweden)

R. Aravindhan

2014-12-01

Full Text Available The present study emphasizes synthesis and bioprofiling of embelin, embelin-metal (EM and embelin-azo-metal (EAM complexes in detail. EM complexes were prepared using pure embelin and d-block transition elements, namely Mn, Fe, Co, Ni, Cu, and Zn. Similarly, EAM complexes were synthesized using phenyl azo-embelin with the said transition metals. Embelin, EM, and EAM complexes were subjected to ultra violet visible spectroscopy, Fourier transform infrared spectroscopy, nuclear magnetic resonance, electrospray ionization mass spectrometry, thermogravimetric analysis, carbon hydrogen nitrogen sulfur analysis. With regard to bioprofiling, the test complexes were studied for the antioxidant and antimicrobial activities. Results revealed that the prepared EM and EAM complexes form octahedral complexes with embelin with the yield in the range of 45–75%. All the instrumental analyses authenticate the interaction of metals with bidentate embelin through its enolic and quinonic oxygen atoms as [M(Emb2(H2O2]H2O and [M(Emb-Azo2(H2O2]. The antioxidant profile studies suggested that upon complexation with metals, the free radical scavenging activity of embelin reduced significantly. But, with regard to antimicrobial activity, cobalt and nickel embelin complexes displayed>80% growth inhibition in comparison with embelin alone. The hemolytic activity studies suggested that both embelin and the metal complexes are non-hemolytic. The reason for the reduction in antioxidant and an increase in antimicrobial activities were discussed in detail.

MOCVD and ALD of rare earth containing multifunctional materials. From precursor chemistry to thin film deposition and applications

International Nuclear Information System (INIS)

Milanov, Andrian Petrov

2010-01-01

The present thesis deals with the development of metal-organic complexes of rare elements. They should be used as novel precursors for the production of rare earth thin films by metal-organic chemical vapor deposition (MOCVD) and Atomic Layer Deposition (ALD). Within the work two precursor classes were examined, the tris-Malonato-complexes as well as the tris-Guanidinato-complexes of a series of rare earth metals. The latter showed excellent properties regarding to their volatility, their thermal stability, the defined decomposition and high reactivity towards water. They have been successfully used as precursors for the MOCVD of rare earth oxide layers. By using of a gadolinium guanidinate it could also be shown that the rare earth guanidinates are promising precursors for ALD of rare earth oxide and MOCVD of rare earth nitride layers. [de

Metal plasmon enhanced europium complex luminescence

International Nuclear Information System (INIS)

Liu Feng; Aldea, Gabriela; Nunzi, Jean-Michel

2010-01-01

The plasmon enhanced luminescence of a rare-earth complex Tris(6, 6, 7, 7, 8, 8, 8-heptafluoro-2, 2-dimethyl-3, 5-octanedionato) europium (Eu(fod) 3 ) was investigated. A polyvinyl alcohol (PVA) thin film was successfully adopted as a spacer to separate the Eu complex from the silver island film (SIF), and five-fold enhancement of the radiative decay rate of the Eu complex on SIF was demonstrated based on the luminescence intensity and lifetime measurement. Investigation of the distance dependent luminescence indicates that 7 nm is an optimal distance for SIF enhanced Eu luminescence. Plasmon enhanced rare-earth luminescence based on an organic film spacer would find potential applications in plasmon enhanced organic light emitting diode (OLED) devices.

Metal complex derivatives of hydrogen uranyl phosphate

International Nuclear Information System (INIS)

Grohol, D.; Blinn, E.L.

1994-01-01

Derivatives of hydrogen uranyl phosphate were prepared by incorporating transition metal complexes into the uranyl phosphate matrix. The transition metal complexes employed include bis(ethylenediamine)copper(II), bis(1,3-propanediamine)copper(II) chloride, (triethylenetetramine)copper(II), (1,4,8,11-tetraazacyclotetradecane)copper(II), (1,4,8,12-tetraazacyclopentadecane)copper(II), (1,4,8,11-tetraazacyclotetradecane)nickel(II) chloride, (triethylenetetramine)nickel(II) and others. The chemical analyses of these derivatives indicated that the incorporation of the transition metal complexes into the uranyl phosphate matrix via ion exchange was not stoichiometric. The extent of ion exchange is dependent on the size and structure of the transition metal complex. All complexes were characterized by X-ray powder diffractometry, electronic and infrared spectra, thermal analyses and chemical analysis. An attempt was made to correlate the degree of quenching of the luminescence of the uranyl ion to the spacing between the uranyl phosphate layers in the derivatives

Biological activities of some Fluoroquinolones-metal complexes

African Journals Online (AJOL)

McRoy

DNA cleavage studies of some synthesized metal complexes of fluoroquinolone ... Although the FQs are generally characterized by a broad antimicrobial spectrum ..... six Coordinate 3rd metal complexes with N- (5 –Phenyl-3,4- thiadiazol-2-yl).

Study on silicon oxide coated on silver nanocrystal to enhance fluorescence intensity of rare earth complexes

Energy Technology Data Exchange (ETDEWEB)

Qu, Yan-rong; Lin, Xue-mei; Wang, Ai-ling; Wang, Zhong-xia; Kang, Jie; Chu, Hai-bin, E-mail: binghai99@gmail.com; Zhao, Yong-liang, E-mail: hxzhaoyl@163.com

2014-10-15

Twelve kinds of rare earth complexes were synthesized using halo-benzoic acid as anion ligand and Sm{sup 3+} and Dy{sup 3+} as central ions, respectively. The complexes were characterized by elemental analysis, rare earth coordination titration and electrospray ionization mass spectra, from which the compositions of the complexes were confirmed to be RE(p-FBA){sub 3}·H{sub 2}O, RE(p-ClBA){sub 3}·2H{sub 2}O, RE(p-BrBA){sub 3}·H{sub 2}O, RE(o-FBA){sub 3}·2H{sub 2}O, RE(o-ClBA){sub 3}·H{sub 2}O, RE(o-BrBA){sub 3}·H{sub 2}O (RE=Sm{sup 3+}, Dy{sup 3+}). Besides, IR spectra and UV–visible absorption spectroscopy indicated that the carboxyl oxygen atoms of ligands coordinated to the rare earth ions. Moreover, Ag@SiO{sub 2} core–shell nanoparticles (NPs) were prepared via a modified Stöber method. The average diameters of silver cores were typically between 60 nm and 70 nm, and the thicknesses of the SiO{sub 2} shells were around 10 nm, 15 nm and 25 nm, respectively. The influence of Ag@SiO{sub 2} NPs on the luminescence properties of the rare earth complexes showed that the luminescence intensities of rare earth complexes were enhanced remarkably. As the thickness of SiO{sub 2} shell increases in the range of 10–25 nm, the effect of metal-enhanced fluorescence become obvious. The mechanism of the changes of the fluorescence intensity is also discussed. - Highlights: • Among 10–25 nm, the thicker the shell thickness, the better the fluorescence effect. • The strong the intensity of the pure complexes, the smaller the multiple enhanced. • The intensity of Sm(p-BrBA){sub 3}·H{sub 2}O is the strongest among Sm(p-XBA){sub 3}·nH{sub 2}O complexes. • The intensity of Dy(p-ClBA){sub 3}·2H{sub 2}O is the strongest among Dy(p-XBA){sub 3}·nH{sub 2}O complexes. • When halogen is in o-position, the intensity of RE(o-ClBA){sub 3}·H{sub 2}O is the strongest.

Multilayer membranes of p-sulfonato-calix[8]arene and polyvinylamine and their use for selective enrichment of rare earth metal ions

Energy Technology Data Exchange (ETDEWEB)

Toutianoush, Ali [Institut fuer Physikalische Chemie der Universitaet zu Koeln, Luxemburger Str. 116, D-50939 Cologne (Germany); El-Hashani, Ashraf [Institut fuer Physikalische Chemie der Universitaet zu Koeln, Luxemburger Str. 116, D-50939 Cologne (Germany); Schnepf, Judit [Institut fuer Physikalische Chemie der Universitaet zu Koeln, Luxemburger Str. 116, D-50939 Cologne (Germany); Tieke, Bernd [Institut fuer Physikalische Chemie der Universitaet zu Koeln, Luxemburger Str. 116, D-50939 Cologne (Germany)]. E-mail: Tieke@Uni-Koeln.de

2005-06-30

Using alternating electrostatic layer-by-layer assembly of p-octasulfonato-calix[8]arene and polyvinylamine, multilayer assemblies were built up on porous polymer supports. The resulting composite membranes with ultrathin separation layer were studied on their permeability for various metal chloride salts in aqueous solution. The membranes were permeable for sodium chloride, but much less permeable for divalent metal chlorides such as magnesium and zinc chloride, the theoretical separation factors {alpha} (NaCl/MgCl{sub 2}) and {alpha} (NaCl/ZnCl{sub 2}) being 43 and 20. Rare earth metal chlorides LnCl{sub 3} with Ln being La, Ce, Pr and Sm and the related YCl{sub 3} were strongly rejected from the membrane, the theoretical separation factors {alpha} (NaCl/LaCl{sub 3}) and {alpha} (NaCl/YCl{sub 3}) being 138 and 160, for example. Possible origins for the selective ion transport are discussed in terms of Donnan rejection of the highly charged ions and complex formation of the rare earth metal ions with the p-sulfonato-calixarene units in the membrane.

Multilayer membranes of p-sulfonato-calix[8]arene and polyvinylamine and their use for selective enrichment of rare earth metal ions

International Nuclear Information System (INIS)

Toutianoush, Ali; El-Hashani, Ashraf; Schnepf, Judit; Tieke, Bernd

2005-01-01

Using alternating electrostatic layer-by-layer assembly of p-octasulfonato-calix[8]arene and polyvinylamine, multilayer assemblies were built up on porous polymer supports. The resulting composite membranes with ultrathin separation layer were studied on their permeability for various metal chloride salts in aqueous solution. The membranes were permeable for sodium chloride, but much less permeable for divalent metal chlorides such as magnesium and zinc chloride, the theoretical separation factors α (NaCl/MgCl 2 ) and α (NaCl/ZnCl 2 ) being 43 and 20. Rare earth metal chlorides LnCl 3 with Ln being La, Ce, Pr and Sm and the related YCl 3 were strongly rejected from the membrane, the theoretical separation factors α (NaCl/LaCl 3 ) and α (NaCl/YCl 3 ) being 138 and 160, for example. Possible origins for the selective ion transport are discussed in terms of Donnan rejection of the highly charged ions and complex formation of the rare earth metal ions with the p-sulfonato-calixarene units in the membrane

Narcissistic self-sorting in self-assembled cages of rare Earth metals and rigid ligands.

Science.gov (United States)

Johnson, Amber M; Wiley, Calvin A; Young, Michael C; Zhang, Xing; Lyon, Yana; Julian, Ryan R; Hooley, Richard J

2015-05-04

Highly selective, narcissistic self-sorting can be achieved in the formation of self-assembled cages of rare earth metals with multianionic salicylhydrazone ligands. The assembly process is highly sensitive to the length of the ligand and the coordination geometry. Most surprisingly, high-fidelity sorting is possible between ligands of identical coordination angle and geometry, differing only in a single functional group on the ligand core, which is not involved in the coordination. Supramolecular effects allow discrimination between pendant functions as similar as carbonyl or methylene groups in a complex assembly process. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Crystal field in rare-earth metals and intermetallic compounds

International Nuclear Information System (INIS)

Ray, D.K.

1978-01-01

Reasons for the success of the crystal-field model for the rare-earth metals and intermetallic compounds are discussed. A review of some of the available experimental results is made with emphasis on cubic intermetallic compounds. Various sources of the origin of the crystal field in these metals are discussed in the background of the recent APW picture of the conduction electrons. The importance of the non-spherical part of the muffin-tin potential on the single-ion anisotropy is stressed. (author)

Selective extraction and recovery of rare earth metals from phosphor powders in waste fluorescent lamps using an ionic liquid system.

Science.gov (United States)

Yang, Fan; Kubota, Fukiko; Baba, Yuzo; Kamiya, Noriho; Goto, Masahiro

2013-06-15

The recycling of rare earth metals from phosphor powders in waste fluorescent lamps by solvent extraction using ionic liquids was studied. Acid leaching of rare earth metals from the waste phosphor powder was examined first. Yttrium (Y) and europium (Eu) dissolved readily in the acid solution; however, the leaching of other rare earth metals required substantial energy input. Ionization of target rare earth metals from the waste phosphor powders into the leach solution was critical for their successful recovery. As a high temperature was required for the complete leaching of all rare earth metals, ionic liquids, for which vapor pressure is negligible, were used as an alternative extracting phase to the conventional organic diluent. An extractant, N, N-dioctyldiglycol amic acid (DODGAA), which was recently developed, showed a high affinity for rare earth metal ions in liquid-liquid extraction although a conventional commercial phosphonic extractant did not. An effective recovery of the rare earth metals, Y, Eu, La and Ce, from the metal impurities, Fe, Al and Zn, was achieved from the acidic leach solution of phosphor powders using an ionic liquid containing DODGAA as novel extractant system. Copyright © 2013 Elsevier B.V. All rights reserved.

Corrosion-electrochemical and mechanical properties of aluminium-berylium alloys alloyed by rare-earth metals

International Nuclear Information System (INIS)

Safarov, A.M.; Odinaev, Kh.E.; Shukroev, M.Sh.; Saidov, R.Kh.

1997-01-01

In order to study influence of rare earth metals on corrosion-electrochemical and mechanical properties of aluminium-berylium alloys the alloys contain 1 mass % beryllium and different amount of rare earth metals were obtained.-electrochemical and mechanical properties of aluminium-berylium alloys. The electrochemical characteristics of obtained alloys, including stationary potential, potentials of passivation beginning and full passivation, potentials of pitting formation and re passivation were defined.

Complex formation constant and hydration number change of aqua-rare earth ions

International Nuclear Information System (INIS)

Kanno, H.

1998-01-01

Full text: It is now well established that the inner-sphere hydration number of aqua-rare earth ions changes from nine to eight in the middle of the rare earth series. This hydration number change greatly affects the complex formation of rare earth ions as we observe irregular variations in most series behaviours of the complex formation constant (K) in aqueous solution systems when K being plotted against 1/r or r (r is ionic radius of rare earth ion). Furthermore, it shows very anomalous concentration dependence in the sense that nona-aqua Ln 3+ ion increases in number with increase in salt concentration in aqueous rare earth salt solution (salt chloride, perchlorate). In this report, a theoretical derivation of the formation constant (K) for the inner-sphere complex formation of rare earth ions with a monodentate ligand was made by taking account of both the hydration number change in the middle of the series and its anomalous salt concentration dependence. The series behaviour of the formation constant against 1/r (or r) is successfully explained with using the empirical finding that K varies almost linearly with 1/r (or r) in the region where only one hydration number dominates. This success is also taken as evidence that the anomalous salt concentration dependence of the hydration number change is caused by the outer-sphere complex formation of rare earth ions with the condition that nona-aqua rare earth ions form outer-sphere complexes more easily than octa-aqua ions

Melting temperature and structural transformation of some rare-earth metals

International Nuclear Information System (INIS)

Vu Van Hung; Hoang Van Tich; Dang Thanh Hai

2009-01-01

the pressure dependence of the melting temperatures of rare-earth metals is studied using the equation of states derived from the statistical moment (SMM). SMM studies were carried out order to calculate the Helmholtz free energy of hcp, bcc Dy and fcc, bcc Ce metals at a wide range of temperatures. the stable phase of Dy and Ce metals can be determined by examining the Helmholtz free energy at a given temperature, i, e. the phase that gives the lowest free energy will be stable. For example, we found that at T lower than 1750 K the hcp Dy metal is stable. At T higher than 1750 K the bcc Dy metal is also stable. Thus 1750 K marks the phase transition temperature of Dy metal. These findings are in agreement with previous experiments. (author)

A rare earth-based metal-organic framework for moisture removal and control in confined spaces

KAUST Repository

Eddaoudi, Mohamed

2017-04-13

A method for preparing a metal-organic framework (MOF) comprising contacting one or more of a rare earth metal ion component with one or more of a tetratopic ligand component, sufficient to form a rare earth-based MOF for controlling moisture in an environment. A method of moisture control in an environment comprising adsorbing and/or desorbing water vapor in an environment using a MOF, the MOF including one or more of a rare earth metal ion component and one or more of a tetratopic ligand component. A method of controlling moisture in an environment comprising sensing the relative humidity in the environment comprising a MOF; and adsorbing water vapor on the MOF if the relative humidity is above a first level, sufficient to control moisture in an environment. The examples relate to a MOF created from 1,2,4,5-Tetrakis(4-carboxyphenyl )benzene (BTEB) as tetratopic ligand, 2-fluorobenzoic acid and Y(NO3)3, Tb(NO3)3 and Yb(NO3)3 as rare earth metals.

Complexes of natural carbohydrates with metal cations

International Nuclear Information System (INIS)

Alekseev, Yurii E; Garnovskii, Alexander D; Zhdanov, Yu A

1998-01-01

Data on the interaction of natural carbohydrates (mono-, oligo-, and poly-saccharides, amino sugars, and natural organic acids of carbohydrate origin) with metal cations are surveyed and described systematically. The structural diversity of carbohydrate metal complexes, caused by some specific features of carbohydrates as ligands, is demonstrated. The influence of complex formation on the chemical properties of carbohydrates is discussed. It is shown that the formation of metal complexes plays an important role in the configurational and conformational analysis of carbohydrates. The practical significance of the coordination interaction in the series of carbohydrate ligands is demonstrated. The bibliography includes 571 references.

Adsorption of alkali and alkaline-earth metal atoms on stanene: A first-principles study

Energy Technology Data Exchange (ETDEWEB)

Kadioglu, Yelda; Ersan, Fatih [Department of Physics, Adnan Menderes University, 09100 Aydın (Turkey); Gökoğlu, Gökhan [Department of Physics, Karabük University, 78050 Karabük (Turkey); Aktürk, Olcay Üzengi [Department of Electrical & Electronics Engineering, Adnan Menderes University, 09100 Aydın (Turkey); Nanotechnology Application and Research Center, Adnan Menderes University, 09100 Aydın (Turkey); Aktürk, Ethem, E-mail: ethem.akturk@adu.edu.tr [Department of Physics, Adnan Menderes University, 09100 Aydın (Turkey); Nanotechnology Application and Research Center, Adnan Menderes University, 09100 Aydın (Turkey)

2016-09-01

This paper presents a study on the adsorption of alkali and alkaline-earth metal atoms on single-layer stanene with different levels of coverage using first-principles plane wave calculations within spin-polarized density functional theory. The most favorable adsorption site for alkali atoms (Li, Na, K) were found to be the hollow site similar to other group IV single-layers, but the case of alkaline-earths on stanene is different from silicene and germanene. Whereas Mg and Ca are bound to stanene at hollow site, the bridge site is found to be energetically favorable for Be adatom. All adsorbed atoms are positively charged due to the charge transfer from adatom to stanene single-layer. The semimetallic bare stanene become metallic except for Be adsorption. The Beryllium adsorption give rise to non-magnetic semiconducting ground state. Our results illustrate that stanene has a reactive and functionalizable surface similar to graphene or silicene. - Highlights: • Alkali and alkaline-earth metal atoms form stronger bonds with stanene compared to other group IV monolayers. • Semi-metallic stanene becomes nonmagnetic metal for Li, Na, K, Mg, and Ca atoms adsorption. • Semi-metallic stanene becomes nonmagnetic semiconductor with 94 meV band gap for Be atom adsorption.

High coercivity rare earth-transition metal magnets

International Nuclear Information System (INIS)

Croat, J.J.

1982-01-01

Ferromagnetic compositions having intrinsic magnetic coercivities at room temperature of at least 1,000 Oersteds are formed by the controlled quenching of molten rare earth-transition metal alloys. Hard magnets may be inexpensively formed from the lower atomic weight lanthanide elements and iron. The preferable compositions lie within: at least one of Fe, Ni, Co; 20 - 70 atomic percent: at least one of Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Y; 80 - 30 atomic percent. (author)

Solution thermodynamics of rare-earth metal ions - physicochemical study-

Energy Technology Data Exchange (ETDEWEB)

Amerkhanova, Sh K; Shlyapov, R M; Uali, A S [Buketov Karaganda state university, University str., 28, Karaganda, 100028 (Kazakhstan)], E-mail: amerkhanova_sh@mail.ru

2009-02-01

The results of the studying of interactions in multicomponent systems 'polyvinyl alcohol (PVA) - rare-earth element ion - nitrate of sodium - water' are represented. It is established that for rubidium (I) ions temperature and ionic strength is render destroying action, and for yttrium (III) ions the influence of these factors has return character which is connected with features of an electronic structure of metal ion. It is revealed that a dominating role of non-electrostatic formation composed, hence, the formation of donor-acceptor connection of 'metal - ligand' occurs through atom of oxygen.

Chances for earth-like planets and life around metal-poor stars

OpenAIRE

Zinnecker, Hans

2003-01-01

We discuss the difficulties of forming earth-like planets in metal-poor environments, such as those prevailing in the Galactic halo (Pop II), the Magellanic Clouds, and the early universe. We suggest that, with less heavy elements available, terrestrial planets will be smaller size and lower mass than in our solar system (solar metallicity). Such planets may not be able to sustain life as we know it. Therefore, the chances of very old lifeforms in the universe are slim, and a threshold metall...

Correlations in rare-earth transition-metal permanent magnets

International Nuclear Information System (INIS)

Skomski, R.; Manchanda, P.; Kashyap, A.

2015-01-01

It is investigated how electron-electron correlations affect the intrinsic properties of rare-earth transition-metal magnets. Focusing on orbital moment and anisotropy, we perform model calculations for 3d-4f alloys and density-functional theory (DFT) calculations for NdCo 5 . On an independent-electron level, the use of a single Slater determinant with broken spin symmetry introduces Hund's rule correlations, which govern the behavior of rare-earth ions and of alloys described by the local spin density approximation (LSDA) and LSDA + U approximations to DFT. By contrast, rare-earth ions in intermetallics involve configuration interactions between two or more Slater determinants and lead to phenomena such as spin-charge distribution. Analyzing DFT as a Legendre transformation and using Bethe's crystal-field theory, we show that the corresponding density functionals are very different from familiar LSDA-type expressions and outline the effect of spin-charge separation on the magnetocrystalline anisotropy

Correlations in rare-earth transition-metal permanent magnets

Science.gov (United States)

Skomski, R.; Manchanda, P.; Kashyap, A.

2015-05-01

It is investigated how electron-electron correlations affect the intrinsic properties of rare-earth transition-metal magnets. Focusing on orbital moment and anisotropy, we perform model calculations for 3d-4f alloys and density-functional theory (DFT) calculations for NdCo5. On an independent-electron level, the use of a single Slater determinant with broken spin symmetry introduces Hund's rule correlations, which govern the behavior of rare-earth ions and of alloys described by the local spin density approximation (LSDA) and LSDA + U approximations to DFT. By contrast, rare-earth ions in intermetallics involve configuration interactions between two or more Slater determinants and lead to phenomena such as spin-charge distribution. Analyzing DFT as a Legendre transformation and using Bethe's crystal-field theory, we show that the corresponding density functionals are very different from familiar LSDA-type expressions and outline the effect of spin-charge separation on the magnetocrystalline anisotropy.

Quinonoid metal complexes: toward molecular switches.

Science.gov (United States)

Dei, Andrea; Gatteschi, Dante; Sangregorio, Claudio; Sorace, Lorenzo

2004-11-01

The peculiar redox-active character of quinonoid metal complexes makes them extremely appealing to design materials of potential technological interest. We show here how the tuning of the properties of these systems can be pursued by using appropriate molecular synthetic techniques. In particular, we focus our attention on metal polyoxolene complexes exhibiting intramolecular electron transfer processes involving either the ligand and the metal ion or the two dioxolene moieties of a properly designed ligand thus inducing electronic bistability. The transition between the two metastable electronic states can be induced by different external stimuli such as temperature, pressure, light, or pH suggesting the use of these systems for molecular switches.

Study of alkaline-earth element complexes in anhydrous acetic acid

International Nuclear Information System (INIS)

Petit, N.

1968-10-01

We have studied the complexes of alkaline-earth elements in anhydrous acetic acid. Using glass-electrode potentiometry we have studied the titration of alkaline earth acetates with perchloric acid which is the strongest acid in anhydrous acetic acid. These titrations have shown that the basic strength of these acetates increases as follows: Mg 4 ); the mixed acetate-acid sulfate complex of barium: Ba (OAc)(HSO 4 ); the mixed acetate-chloride of barium: Ba (OAc)(Cl). (author) [fr

Alkaline earth metal doped tin oxide as a novel oxygen storage material

Energy Technology Data Exchange (ETDEWEB)

Dong, Qiang, E-mail: dong@tagen.tohoku.ac.jp [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku Sendai 980-8577 (Japan); Yin, Shu; Yoshida, Mizuki; Wu, Xiaoyong; Liu, Bin [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku Sendai 980-8577 (Japan); Miura, Akira; Takei, Takahiro; Kumada, Nobuhiro [Department of Research Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Miyamae cho-7, Kofu 400-8511 (Japan); Sato, Tsugio [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku Sendai 980-8577 (Japan)

2015-09-15

Alkaline earth metal doped tin oxide (SnO{sub 2}) hollow nanospheres with a diameter of 50 nm have been synthesized successfully via a facial solvothermal route in a very simple system composed of only ethanol, acetic acid, SnCl{sub 4}·5H{sub 2}O and A(NO{sub 3}){sub 2}·xH{sub 2}O (A = Mg, Ca, Sr, Ba). The synthesized undoped SnO{sub 2} and A-doped SnO{sub 2} hollow nanospheres were characterized by the oxygen storage capacity (OSC), X-ray diffraction, transmission electron microscopy and the Brunauer–Emmet–Teller (BET) technique. The OSC values of all samples were measured using thermogravimetric-differential thermal analysis. The incorporation of alkaline earth metal ion into tin oxide greatly enhanced the thermal stability and OSC. Especially, Ba-doped SnO{sub 2} hollow nanospheres calcined at 1000 °C for 20 h with a BET surface area of 61 m{sup 2} g{sup −1} exhibited the considerably high OSC of 457 μmol-O g{sup −1} and good thermal stability. Alkaline earth metal doped tin oxide has the potential to be a novel oxygen storage material.

A study of new rare-earth metal group-13 chalcohalides. Structures, chemistry, and optical properties

International Nuclear Information System (INIS)

Dorhout, P.K.; Van Calcar, P.M.

1998-01-01

Full text: Several new quaternary compounds from the rare-earth metal group-13 chalcohalide family have been prepared from alkaline earth halide flux reactions of binary and elemental starting materials. One compound, for example, Ca 2 La 6G a 2 S 1 4 , crystallizes as needles in an hexagonal cell while another, more disordered structure, La 11 Ga 19 Cl 6 S 42 , crystallizes as monoclinic plates. The former is a condensed structure with channels that contain the alkaline earth element while the latter forms a layered structure containing rare-earth halide clusters within interlayer galleries. These compounds are new members of a family of rare-earth metal main-group chalcogenides which show promise as electroluminescent materials. Structural and spectroscopic studies of these and related compounds will be discussed

High coercivity rare earth-transition metal magnets

International Nuclear Information System (INIS)

Croat, J.J.

1982-01-01

Ferromagnetic compositions having intrinsic magnetic coercivities at room temperature of at least 1,000 Oersteds are formed by the controlled quenching of molten rare earth -transition metal alloys. Hard magnets may be inexpensively formed from the lower atomic weight lanthanide elements and iron. The preferable compositions lie within: at least one of Fe, Ni, Co (20 to 70 atomic percent); and at least one of Ce, Pr, Na, Sm, Eu, Tb, Dy, Ho, Er, Tm, Y (80 to 30 atomic percent). (author)

Electronic Structure of Rare-Earth Metals. II. Positron Annihilation

DEFF Research Database (Denmark)

Williams, R. W.; Mackintosh, Allan

1968-01-01

of Loucks shows that the independent-particle model gives a good first approximation to the angular distribution, although correlation effects probably smear out some of the structure. The angular distributions from the heavy rare-earth metals are very similar to that from Y and can be understood....... In the spiral phase of Ho, the structure in the c-axis distribution is much reduced, indicating that the Fermi surface is substantially modified by the magnetic ordering, as expected. The photon distribution from the equiatomic Ho-Er alloy is very similar to those from the constituent metals, although...

Cell complexes of transition metals in biochemistry and medicine

International Nuclear Information System (INIS)

Voloshin, Ya.Z.; Varzatskij, O.A.; Bubnov, Yu.N.

2007-01-01

Basic directions and prospects of use of cell complexes of transition metals in medicine and biochemistry are considered: incapsulation of radioactive metal ions for radiotherapy and diagnostics; preparation of contrast compounds for magnetic resonance tomography, antidotes and pharmaceutical preparation of prolonged effect, preparations for boron-neutron-capture therapy of neoplasms, antioxidants; membrane transport of metal ions; study of interaction of cell metal complexes with nucleic acids; possibility of use of self-assembly of cell complexes for imitation of ligases and use of clathrochelates as linkers; design of inhibitors of viruses for AIDS therapy [ru

Effect of rare earth metal on the spin-orbit torque in magnetic heterostructures

Energy Technology Data Exchange (ETDEWEB)

Ueda, Kohei; Pai, Chi-Feng; Tan, Aik Jun; Mann, Maxwell; Beach, Geoffrey S. D., E-mail: gbeach@mit.edu [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2016-06-06

We report the effect of the rare earth metal Gd on current-induced spin-orbit torques (SOTs) in perpendicularly magnetized Pt/Co/Gd heterostructures, characterized using harmonic measurements and spin-torque ferromagnetic resonance (ST-FMR). By varying the Gd metal layer thickness from 0 nm to 8 nm, harmonic measurements reveal a significant enhancement of the effective fields generated from the Slonczewski-like and field-like torques. ST-FMR measurements confirm an enhanced effective spin Hall angle and show a corresponding increase in the magnetic damping constant with increasing Gd thickness. These results suggest that Gd plays an active role in generating SOTs in these heterostructures. Our finding may lead to spin-orbitronics device application such as non-volatile magnetic random access memory, based on rare earth metals.

Metal complexes with 5-aminotetrazole

International Nuclear Information System (INIS)

Lavrenova, L.G.; Larionov, S.V.; Grankina, Z.A.; Ikorskij, V.N.

1983-01-01

Nitrate and chloride complexes of Co(2), Ni(2), Cu(2), Cd(2), Hg(2), Pb(2) with 5 aminotetrazole (ATE) and compoUnds Zn(ATE') 2 and Cd(ATEE') 2 , where ATE' is a 5 aminotetrazole ano /nion. On the base of spectroscopic data (spectrophotometry, IR- spectra, EPR and magnetic measurements assumptions on M(2) coordination in complexes are made. Most probably ATE is a bridge ligand which is joined by two nitrogen atoms to various M(2) ions. In Co(2), Ni(2) and Cu(ATE) 3 -Cl 2 compounds the metal has a distorted actahedral coordination and forms MN 6 unit, which suggests the interaction of metal ions with ATE nitrogen atoms along the Z-axis. In the Cu(ATE) 2 (NO 3 ) 2 octahedral complex the CuN 4 O 2 coordination unit is realized at the expense of participation of nitratogroups in coordination

Dissolution of Fe(III) (hydr) oxides by metal-EDTA complexes

Science.gov (United States)

Ngwack, Bernd; Sigg, Laura

1997-03-01

The dissolution of Fe(III)(hydr)oxides (goethite and hydrous ferric oxide) by metal-EDTA complexes occurs by ligand-promoted dissolution. The process is initiated by the adsorption of metal-EDTA complexes to the surface and is followed by the dissociation of the complex at the surface and the release of Fe(III)EDTA into solution. The dissolution rate is decreased to a great extent if EDTA is complexed by metals in comparison to the uncomplexed EDTA. The rate decreases in the order EDTA CaEDTA ≫ PbEDTA > ZnEDTA > CuEDTA > Co(II)EDTA > NiEDTA. Two different rate-limiting steps determine the dissolution process: (1) detachment of Fe(III) from the oxide-structure and (2) dissociation of the metal-EDTA complexes. In the case of goethite, step 1 is slower than step 2 and the dissolution rates by various metals are similar. In the case of hydrous ferric oxide, step 2 is rate-limiting and the effect of the complexed metal is very pronounced.

Technique for recovering rare-earth metals from spent sintered Nd-Fe-B magnets without external heating

Directory of Open Access Journals (Sweden)

Ryo Sasai

2016-06-01

Full Text Available To selectively recover rare-earth metals with higher purity from spent sintered Nd-Fe-B magnets without external heating, we investigated the mechano-chemical treatment of spent sintered Nd-Fe-B magnet powder with a reaction solution of HCl and (COOH2 at room temperature. The results of various experiments showed that the mechano-chemical treatment with HCl and (COOH2 is very effective for recovering the rare-earth metals contained in spent sintered Nd-Fe-B magnet powder; the recovery rate and purity of the rare-earth metals were 95.3 and 95.0 mass%, respectively, under optimal conditions ([HCl] = 0.2 mol/dm3 and [(COOH2] = 0.25 mol/dm3.

Observation of vapor pressure enhancement of rare-earth metal-halide salts in the temperature range relevant to metal-halide lamps

Energy Technology Data Exchange (ETDEWEB)

Curry, J. J.; Henins, A.; Hardis, J. E. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Estupinan, E. G. [Osram Sylvania Inc., Beverly, Massachusetts 01915 (United States); Lapatovich, W. P. [Independent Consultant, 51 Pye Brook Lane, Boxford, Massachusetts 01921 (United States); Shastri, S. D. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2012-02-20

Total vapor-phase densities of Dy in equilibrium with a DyI{sub 3}/InI condensate and Tm in equilibrium with a TmI{sub 3}/TlI condensate have been measured for temperatures between 900 K and 1400 K. The measurements show strong enhancements in rare-earth vapor densities compared to vapors in equilibrium with the pure rare-earth metal-halides. The measurements were made with x-ray induced fluorescence on the sector 1-ID beam line at the Advanced Photon Source. The temperature range and salt mixtures are relevant to the operation of metal-halide high-intensity discharge lamps.

The magnetoresistivity of some rare-earth metals

International Nuclear Information System (INIS)

Webber, G.D.

1978-10-01

The thesis describes measurements of the low temperature transverse magnetoresistivities of single crystals of rare-earth metals in magnetic fields up to 8 Tesla. A general introduction to the rare-earths, their magnetic properties and a review of the basic theory and mechanism of magnetoresistivity is given. Details of the crystal structure, growth of single crystals and sample mounting method follow. The experimental equipment and measuring techniques are then described. The low temperature transverse magnetoresistivity of polycrystalline lanthanum and single crystal praseodymium for the temperature range 4.2 - 30K is measured. The separation of the spin-disorder and Fermi-surface orbital effect contributions are described and the theoretical and experimental spin-disorder values compared. Magnetoresistivity measurements for neodymium single crystals (4.2 - 30K) are compared with the magnetic properties determined from neutron diffraction studies. Results for gadolinium single crystals (4.2 - 200K) are compared for two different impurity levels and with previous work. (UK)

Compartmentation and complexation of metals in hyperaccumulator plants

Directory of Open Access Journals (Sweden)

Barbara eLeitenmaier

2013-09-01

Full Text Available Hyperaccumulators are being intensely investigated. They are not only interesting in scientific context due to their strange behaviour in terms of dealing with high concentrations of metals, but also because of their use in phytoremediation and phytomining, for which understanding the mechanisms of hyperaccumulation is crucial. Hyperaccumulators naturally use metal accumulation as a defence against herbivores and pathogens, and therefore deal with accumulated metals in very specific ways of complexation and compartmentation, different from non-hyperaccumulator plants and also non-hyperaccumulated metals. For example, in contrast to non-hyperaccumulators, in hyperaccumulators even the classical phytochelatin-inducing metal, cadmium, is predominantly not bound by such sulfur ligands, but only by weak oxygen ligands. This applies to all hyperaccumulated metals investigated so far, as well as hyperaccumulation of the metalloid arsenic. Stronger ligands, as they have been shown to complex metals in non-hyperaccumulators, are in hyperaccumulators used for transient binding during transport to the storage sites. This confirmed that enhanced active metal transport, and not metal complexation, is the key mechanism of hyperaccumulation. Hyperaccumulators tolerate the high amount of accumulated heavy metals by sequestering them into vacuoles, usually in large storage cells of the epidermis. This is mediated by strongly elevated expression of specific transport proteins in various tissues from metal uptake in the shoots up to the storage sites in the leaf epidermis. However, this mechanism seems to be very metal specific. Non-hyperaccumulated metals in hyperaccumulators seem to be dealt with like in non-hyperaccumulator plants, i.e. detoxified by binding to strong ligands such as metallothioneins.

High-pressure metallization of FeO and implications for the earth's core

Science.gov (United States)

Knittle, Elise; Jeanloz, Raymond

1986-01-01

The phase diagram of FeO has been experimentally determined to pressures of 155 GPa and temperatures of 4000 K using shock-wave and diamond-cell techniques. A metallic phase of FeO is observed at pressures greater than 70 GPa and temperatures exceeding 1000 K. The metallization of FeO at high pressures implies that oxygen can be present as the light alloying element of the earth's outer core, in accord with the geochemical predictions of Ringwood (1977 and 1979). The high pressures necessary for this metallization suggest that the core has acquired its composition well after the initial stages of the earth's accretion. Direct experimental observations at elevated pressures and temperatures indicate that core-forming alloy can react chemically with oxides such as those forming the mantle. The core and mantle may never have reached complete chemical equilibrium, however. If this is the case, the core-mantle boundary is likely to be a zone of active chemical reactions.

TDPAC studies on metal-complex ferrimagnets

Energy Technology Data Exchange (ETDEWEB)

Ohkubo, Yoshitaka [Kyoto Univ., Kumatori, Osaka (Japan). Research Reactor Inst.; Abe, Shizuko; Okada, Takuya [and others

1997-03-01

TDPAC spectra of {sup 117}In (left-arrow {sup 117}Cd) and {sup 111}Cd (left-arrow {sup 111m}Cd) in the mixed metal complex N(C{sub 4}H{sub 9}){sub 4}(M(II)Fe(III)(C{sub 2}O{sub 4}){sub 3})(M=Fe,Ni), the related substraces and LiNbO{sub 3} have been studied. In this paper, pure potassium iron (III) oxalate was prepared and mixed metal complexes were synthesized by changing amount of reagents and the order added, then observed by TDPAC. 2 mol%Cd was dispersed throughout potassium iron oxalate and potassium nickel oxalate, formulating M(II){sub 0.98}Cd(II){sub 0.02}C{sub 2}O{sub 4}{center_dot}2H{sub 2}O (M=Fe, Ni) with the same crystal structure. The formation reaction of mixed metal complex-Fe(II) was faster than that of iron oxalate. Its mixed metal complex-Ni(II) was slower than that of iron oxalate. The rate of quadrupole oscillation was obtained by {omega}{sub Q}({sup 117}In)=67.3 Mrad/s and {omega}{sub Q}({sup 111}Cd)=29.7 Mrad/s of which values were determined by TDPAC spectra of {sup 117}In and {sup 111}Cd in LiNbO{sub 3} at 4K. The value showed pure ion bond of oxygen coordinated with {sup 117}In and {sup 111}Cd. 0.08 {eta} was determined by TDPAC spectrum of {sup 111}Cd(left-arrow {sup 111m}Cd). The rate of {omega}{sub Q} of mixed metal oxalate complex was larger than 2.3, indicating 5s and 5p orbital electron took part in bond of oxygen of oxalic acid or approaching oxygen ion to In nucleus depend on the structual relaxation in decaying of {sup 117}In(left-arrow {sup 117}Cd). (S.Y.)

Maternal exposure to alkali, alkali earth, transition and other metals: Concentrations and predictors of exposure

International Nuclear Information System (INIS)

Hinwood, A.L.; Stasinska, A.; Callan, A.C.; Heyworth, J.; Ramalingam, M.; Boyce, M.; McCafferty, P.; Odland, J.Ø.

2015-01-01

Most studies of metals exposure focus on the heavy metals. There are many other metals (the transition, alkali and alkaline earth metals in particular) in common use in electronics, defense industries, emitted via combustion and which are naturally present in the environment, that have received limited attention in terms of human exposure. We analysed samples of whole blood (172), urine (173) and drinking water (172) for antimony, beryllium, bismuth, cesium, gallium, rubidium, silver, strontium, thallium, thorium and vanadium using ICPMS. In general most metals concentrations were low and below the analytical limit of detection with some high concentrations observed. Few factors examined in regression models were shown to influence biological metals concentrations and explained little of the variation. Further study is required to establish the source of metals exposures at the high end of the ranges of concentrations measured and the potential for any adverse health impacts in children. - This study has demonstrated exposure to alkali, alkali earth and transition metals in pregnant women with factors such as breastfeeding, fish oil use and diet affecting exposures

The electrodeposition and rare earths reduction in the molten salt actinides recovery systems using liquid metal

International Nuclear Information System (INIS)

Shim, J-B.; Lee, J-H.; Kwon, S-W.; Ahn, B-G.; Woo, M-S.; Lee, B-J.; Kim, E-H.; Park, H-S.; Yoo, J-H.

2005-01-01

A pyrochemical partitioning system uses liquid metals such as cadmium and bismuth in order to recover the actinide metals from a molten salt mixture containing rare earth fission product metals. The liquid metals play roles as a cathode in the electrowinning or an extracting phase in the reductive extraction operation. The product resulting from the above operations is metal-cadmium or-bismuth alloy, which should contain the rare earth element amounts as low as possible for a transmutation purpose. In this study, the electrodeposition behaviours of uranium and lanthanide elements such as La, Ce and Nd were investigated for solid molybdenum and liquid cadmium electrodes in a molten LiCl-KCl eutectic salt. Electrochemical methods used are a cyclic voltammetry (CV) and a chronopotentiometry for monitoring the salt phase and recovering the metals, respectively. The CV graphs for monitoring the oxidizing agent CdCl 2 in the salt phase were obtained. These show a time dependently disappearance of the oxidizing agent corresponding to the formation of UCl 3 by inserting the uranium metal into the salt. Also, a sequential oxidation technique which is added at a controlled amount of the oxidizing agents into the salt phase was applied. It was found that this method is feasible for the selective reduction of the rare earths content in liquid metal alloys. (author)

Ortho-para-conversion of hydrogen in films of rare earth metals

International Nuclear Information System (INIS)

Zhavoronkova, K.N.; Peshkov, A.V.

1979-01-01

Investigated is specific catalytic activity of REE to clarify to what an extent the change of electron structure of the metals might influence their catalytic properties. Conducted is investigation of Sc, It, La and other lanthanides, except Eu amd Pm prepared in the form of metallic films, impowdered in vacuum of 10 -7 torr. It is established, that pape earth elements as catalysts of low-temperature ortho-para-conversion od hydrogen are divided into 2 groups, differing by mechanism of the reaction. Comparison of experimental results with the calculation results of absolute rates of paramagnetic conversion and also with investigation results of isotopjc exchange on these metals showed, that on the metals of group 1 conversjon proceeds according to chemical mechanism, and on the metals of group 2 - according to oscillating magnetic mechanism

Rare earth metals-primary resources and prospects of processing secondary resources in India

International Nuclear Information System (INIS)

Pandey, B.D.

2015-01-01

The importance of Rare earth metals (REMs) in modern technological applications is associated with their spectroscopic and magnetic properties. The occurrence of rare earths in mixed form is commonly reported and their separation to the individual metal is a challenging task because of the similar chemical properties. The economical processing of the primary ores of rare earths is limited to a few countries and their supply at the international level is currently dominated by China. Hence assessing the present scenario of the primary resources of rare earths vis-à-vis their applications and demand is crucial at this stage, besides looking at the alternate resources to ensure availability of REMs; such aspects are covered in the manuscript. In view of the environmental concerns in the processing of ores such as monazite, xenotime, bastnasite, etc, and increasing demand of REMs, corresponding increase in demand of the raw materials has been recorded. It is therefore, necessary to utilize the end-of the-life rare earth containing materials as a rich resource by developing an appropriate recycling technology, which is emerging as a high priority area. To recover the REMs, major secondary resources such as electronic wastes, industrial wastes, spent catalysts and magnets, and phosphors powder, etc, have been considered for now. This will not only open the prospects of utilizing the wastes containing REMs, but will also limit the imports while lowering the production cost and decreasing the load on the primary reserves. The paper also examines the efficient recycling methods to recover a fairly good amount of rare earths which are relevant to India in view of the limited exploitation of the ores. Recovery of REMs from secondary resources using mechanical treatment followed by hydrometallurgical methods is prevalent and the same is reviewed in some detail. The recent R and D work pursued at CSIR-NML to extract (leaching and metal separation using some phosphatic reagents

Loan officers' perceptions concerning earth-sheltered housing: risk, complexity, and advantage

Energy Technology Data Exchange (ETDEWEB)

Hanzai-Kashi, A; Combs, E R

1984-01-01

The lack of available financing is a major impediment to the construction of earth-sheltered housing. A broad-based study of lending institutions, this study describes the perceptions of loan officers toward earth-sheltered housing and their perception of their institution's lending policies in terms of their concerns. The survey finds that a majority of the loan officers perceive more stringent terms and larger down payments for earth-sheltered housing because of their concerns for financial risk, complexity, and relative advantage. Methods to reduce the risk and complexity and to increase the relative advantage would involve marketing research, certification and warranty programs, secondary mortgages markets, and other techniques. 8 references, 5 tables.

Accomplishing simple, solubility-based separations of rare earth elements with complexes bearing size-sensitive molecular apertures.

Science.gov (United States)

Bogart, Justin A; Cole, Bren E; Boreen, Michael A; Lippincott, Connor A; Manor, Brian C; Carroll, Patrick J; Schelter, Eric J

2016-12-27

Rare earth (RE) metals are critical components of electronic materials and permanent magnets. Recycling of consumer materials is a promising new source of rare REs. To incentivize recycling, there is a clear need for the development of simple methods for targeted separations of mixtures of RE metal salts. Metal complexes of a tripodal hydroxylaminato ligand, TriNOx 3- , featured a size-sensitive aperture formed of its three η 2 -(N,O) ligand arms. Exposure of cations in the aperture induced a self-associative equilibrium comprising RE(TriNOx)THF and [RE(TriNOx)] 2 species. Differences in the equilibrium constants K dimer for early and late metals enabled simple separations through leaching. Separations were performed on RE1/RE2 mixtures, where RE1 = La-Sm and RE2 = Gd-Lu, with emphasis on Eu/Y separations for potential applications in the recycling of phosphor waste from compact fluorescent light bulbs. Using the leaching method, separations factors approaching 2,000 were obtained for early-late RE combinations. Following solvent optimization, >95% pure samples of Eu were obtained with a 67% recovery for the technologically relevant Eu/Y separation.

An Operationally Simple Method for Separating the Rare-Earth Elements Neodymium and Dysprosium.

Science.gov (United States)

Bogart, Justin A; Lippincott, Connor A; Carroll, Patrick J; Schelter, Eric J

2015-07-06

Rare-earth metals are critical components of electronic materials and permanent magnets. Recycling of consumer materials is a promising new source of rare earths. To incentivize recycling there is a clear need for simple methods for targeted separations of mixtures of rare-earth metal salts. Metal complexes of a tripodal nitroxide ligand [{(2-(t) BuNO)C6 H4 CH2 }3 N](3-) (TriNOx(3-) ), feature a size-sensitive aperture formed of its three η(2) -(N,O) ligand arms. Exposure of metal cations in the aperture induces a self-associative equilibrium comprising [M(TriNOx)thf]/ [M(TriNOx)]2 (M=rare-earth metal). Differences in the equilibrium constants (Keq ) for early and late metals enables simple Nd/Dy separations through leaching with a separation ratio SNd/Dy =359. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

On the single-ion Magnetic Anisotropy of the Rare-Earth Metals

DEFF Research Database (Denmark)

Kolmakova, N.P.; Tishin, A.M.; Bohr, Jakob

1996-01-01

The temperature dependences of the single-ion magnetic anisotropy constants for Tb and Dy metals are calculated in terms of the multipole moments of the rare-earth ions utilizing the available crystal-field parameters. The results are compared with the existing experimental data....

Complex metal hydrides for hydrogen, thermal and electrochemical energy storage

DEFF Research Database (Denmark)

Møller, Kasper T.; Sheppard, Drew; Ravnsbæk, Dorthe B.

2017-01-01

field. This review illustrates that complex metal hydrides may store hydrogen in the solid state, act as novel battery materials, both as electrolytes and electrode materials, or store solar heat in a more efficient manner as compared to traditional heat storage materials. Furthermore, it is highlighted...... how complex metal hydrides may act in an integrated setup with a fuel cell. This review focuses on the unique properties of light element complex metal hydrides mainly based on boron, nitrogen and aluminum, e.g., metal borohydrides and metal alanates. Our hope is that this review can provide new...

N-acyl thioureas - selective ligands for complexing of heavy metals and noble metals

International Nuclear Information System (INIS)

Schuster, M.

1992-01-01

Acyl thioureas are complexing agents for heavy metals that are easily produced and very stable. Their favourable toxicological data make them particularly suitable for industrial applications, e.g. detoxification of metallic process solutions or solvent extraction of metals. (orig.) [de

Coordination compounds of metals with imidazoles and benzimidazoles. [Metals: V, Th, Mo, Cd, rare earths, etc

Energy Technology Data Exchange (ETDEWEB)

Novikova, G A; Molodkin, A K; Kukalenko, S S

1988-12-01

Methods of preparation, composition and structure of UO/sub 2//sup 2+/, Th/sup 4+/, Mo/sup 3+/, Cd/sup 2+/, Ln/sup 3+/ metal ion complexes with imidazoles and benzimidazoles are considered in reviews of native and foreign literature of up to 1985. Complexes are customarily prepared by direct interaction of ligands with inorganic salts in different organic solvents. Complex composition is defined by the nature of complexing metal and inorganic salt anion, ligand volume and basicity, as well as solvent characteristics. Effect of R substituent in imidazole and benzimidazole side chain on composition of coordination compounds is considered.

DFT study on metal-mediated uracil base pair complexes

Directory of Open Access Journals (Sweden)

Ayhan Üngördü

2017-11-01

Full Text Available The most stable of metal-mediated uracil base pair complexes were determined. Method was used density functional theory, B3LYP. The calculations of systems containing C, H, N, O were described by 6-311++G(d,p and cc-PVTZ basis sets and LANL2DZ and SDD basis sets was used for transition metals. Then Egap values of complexes were calculated and the electrical conductivity of the complexes for single nanowires was studied by band theory. Metal-mediated uracil base pair complexes which will be used as conductive wires in nanotechnology were predicted. In nanoworld, this study is expected to show a way for practical applications.

Sythesis of rare earth metal - GIC graphite intercalation compound in molten chloride system

International Nuclear Information System (INIS)

Ito, Masafumi; Hagiwara, Rika; Ito, Yasuhiko

1994-01-01

Graphite intercalation compounds of ytterbium and neodymium have been prepared by interacting graphite and metals in molten chlorides. These rare earth metals can be suspended in molten chlorides in the presence of trichlorides via disproportionation reaction RE(0) + RE(III) = 2RE(II) at lower than 300 degC. Carbides-free compounds are obtained in these systems. (author)

An operationally simple method for separating the rare-earth elements neodymium and dysprosium

Energy Technology Data Exchange (ETDEWEB)

Bogart, Justin A.; Lippincott, Connor A.; Carroll, Patrick J.; Schelter, Eric J. [Department of Chemistry, University of Pennsylvania, Philadelphia, PA (United States)

2015-07-06

Rare-earth metals are critical components of electronic materials and permanent magnets. Recycling of consumer materials is a promising new source of rare earths. To incentivize recycling there is a clear need for simple methods for targeted separations of mixtures of rare-earth metal salts. Metal complexes of a tripodal nitroxide ligand [{(2-"tBuNO)C_6H_4CH_2}{sub 3}N]{sup 3-} (TriNOx{sup 3-}), feature a size-sensitive aperture formed of its three η{sup 2}-(N,O) ligand arms. Exposure of metal cations in the aperture induces a self-associative equilibrium comprising [M(TriNOx)thf]/[M(TriNOx)]{sub 2} (M=rare-earth metal). Differences in the equilibrium constants (K{sub eq}) for early and late metals enables simple Nd/Dy separations through leaching with a separation ratio S{sub Nd/Dy}=359. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Metal nitride cluster as a template to tune the electronic and magnetic properties of rare-earth metal containing endohedral fullerenes

International Nuclear Information System (INIS)

Zhang, Yang

2013-01-01

Rare-earth metal containing endohedral fullerenes have attracted much attention due to the feasibility of encaging metal atom, atoms or cluster inside of carbon cages. By switching the metal atom or cluster entrapped inside of the carbon cage the physical and chemical properties of the fullerene compounds can be tuned. The understanding of magnetic and electrochemical properties of endohedral fullerenes plays an essential role in fundamental scientific researches and potential applications in materials science. In this thesis, synthesizing novel rare-earth metal containing endohedral fullerene structures, studying the properties of these isolated endohedral fullerenes and the strategies of tuning the electronic and magnetic properties of endohedral fullerenes were introduced. The DC-arc discharging synthesis of different lanthanide metal-based (Ho, Ce and Pr) mixed metal nitride clusterfullerenes was achieved. Those rare-earth metal containing endohedral fullerenes were isolated by multi-step HPLC. The isolated samples were characterized by spectroscopic techniques included UV-vis-NIR, FTIR, Raman, LDI-TOF mass spectrometry, NMR and electrochemistry. The Ho-based mixed metal nitride clusterfullerenes Ho x M 3-x N rate at C 80 (M= Sc, Lu, Y; x=1, 2) were synthesized by ''reactive gas atmosphere'' method or ''selective organic solid'' route. The isolated samples were characterized by LDI-TOF mass spectrometry, UV-vis-NIR, FTIR, Raman and NMR spectroscopy. The 13 C NMR spectroscopic studies demonstrated exceptional NMR behaviors that resulted from switching the second metal inside of the mixed metal nitride cluster Ho x M 3-x N from Sc to Lu and further to Y. The LnSc 2 N rate at C 80 (Ln= Ce, Pr, Nd, Tb, Dy, Ho, Lu) MMNCFs were characterized by 13 C and 45 Sc NMR study respectively. According to Bleaney's theory and Reilley method, the separation of δ PC and δ con from δ para was achieved by the primary 13 C and 45 Sc NMR analysis of LnSc 2 N rate at C 80 (I). The

Vibrational spectra of double rare earth alkaline metal metaphosphates

International Nuclear Information System (INIS)

Madij, V.A.; Krasilov, Yu.I.; Kizel', V.A.; Denisov, Yu.V.; Chudinova, N.N.; Vinogradova, N.V.

1978-01-01

Joint analysis of the Raman and infrared absorption spectra, as well as X-ray structural data for binary metaphosphates, suggest a cyclic structure of the anion in RbEu(PO 3 ) 4 and a chain structure of the anions in HEu(PO 3 ) 4 and LiEu(PO 3 ) 4 . Spectroscopic criteria are proposed for distinguishing between cyclic and chain structures in binary metaphosphates of rare earth elements and alkali metals

Tris-diamine-derived transition metal complexes of flurbiprofen as ...

African Journals Online (AJOL)

admin

butyrylcholinesterase (BChE) inhibitory activities. Method: Tris-diamine-derived transition metal complexes of Co(II), Ni(II), and Mn(II) were synthesized and characterized ... Conductance measurements indicated that diamine-derived metal complexes of ..... contributes to enhanced biological activity, and provides novel ...

Preparation of new phthalocyanine complexes of some rare-earth elements

International Nuclear Information System (INIS)

Sugimoto, Hiroshi; Higashi, Teruaki; Mori, Masayasu

1982-01-01

The reaction of tris(1,3-diphenyl-1,3-propanedionato) complexes of heavier rare-earth elements, M 3+ (dbm) 3 and lithium phthalocyaninato (2-), Li 2 (pc) gave two types of new stable phthalocyanine complexes, [M 3+ (pc)(dbm)(dbmH)] and [M 3+ (pc)(dbm)] depending on the solvents used for the preparation. The structure of both types of complexes are tentatively proposed. (author)

Preliminary analysis on tectonic movement and uranium metallization in Kang-Dian the earth's axis

International Nuclear Information System (INIS)

Luo Yiyue; Wei Mingji; Ma Guangzhong

1998-01-01

On the basis of analyzing available data the authors expounds the regional geology, tectonic movement, as well as the relationship between geological evolution and uranium metallization in Kang-Dian the earth's axis and propose that the Jinning Period (960-1006 Ma) is the first metallogenic epoch of uranium in Kang-Dian the earth's axis

Synthesis and physicochemical study of rare earth complexes with o-hydroxyphenoxymethylphosphonic acid

International Nuclear Information System (INIS)

Alibaeva, Z.M.; Snezhko, N.I.; Pechurova, N.I.; Martynenko, L.I.; Alekseeva, N.A.; Bovin, A.N.

1987-01-01

Rare earth complexes with o-hydroxyphenoxymethylphosphonic acid (C 7 H 9 PO 5 , N 2 L) of the HMl 2 xnH 2 O composition are synthesized. The compounds separated are studied by IR spectroscopy, X-ray phase and elementary analysis methods. The data obtained permit to suppose on the polymer structure of rare earth complexes, except HLaL 2 x2H 2 O which is evidently of the island structure

Mechanics of metal-catecholate complexes: The roles of coordination state and metal types

Science.gov (United States)

Xu, Zhiping

2013-01-01

There have been growing evidences for the critical roles of metal-coordination complexes in defining structural and mechanical properties of unmineralized biological materials, including hardness, toughness, and abrasion resistance. Their dynamic (e.g. pH-responsive, self-healable, reversible) properties inspire promising applications of synthetic materials following this concept. However, mechanics of these coordination crosslinks, which lays the ground for predictive and rational material design, has not yet been well addressed. Here we present a first-principles study of representative coordination complexes between metals and catechols. The results show that these crosslinks offer stiffness and strength near a covalent bond, which strongly depend on the coordination state and type of metals. This dependence is discussed by analyzing the nature of bonding between metals and catechols. The responsive mechanics of metal-coordination is further mapped from the single-molecule level to a networked material. The results presented here provide fundamental understanding and principles for material selection in metal-coordination-based applications. PMID:24107799

Zeolites as supports for transition-metal complexes

Energy Technology Data Exchange (ETDEWEB)

Le Van Mao, R

1979-01-01

The unique structural characteristics of the zeolites, including the presence of molecular-size cages and channels and of an internal electrostatic field, make them promising as supports for converting homogeneous to heterogeneous catalysts. The acidic sites on the zeolites may also contribute to catalysis of reactions, such as hydrocracking; may stabilize metal complexes in a highly disperse state; and may improve activity or selectivity. Recent studies on the synthesis of new types of zeolite-supported complexes of transition metals (TM), such as Co, Cu, Ag, Fe, Mo, Ru, Rh, Re, and Os, suggest the feasibility of the direct introduction of some TM complexes into the zeolitic cages during zeolite synthesis, especially during the crystallization phase. This method may considerably reduce the structural limitations associated with the incorporation of TM complexes into zeolites by conventional methods.

Metallacyclopentadienes: structural features and coordination in transition metal complexes

International Nuclear Information System (INIS)

Dolgushin, Fedor M; Yanovsky, Aleksandr I; Antipin, Mikhail Yu

2004-01-01

Results of structural studies of polynuclear transition metal complexes containing the metallacyclopentadiene fragment are overviewed. The structural features of the complexes in relation to the nature of the substituents in the organic moiety of the metallacycles, the nature of the transition metals and their ligand environment are analysed. The main structural characteristics corresponding to different modes of coordination of metallacyclopentadienes to one or two additional metal centres are revealed.

40 CFR 721.4596 - Diazo substituted carbomonocyclic metal complex.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Diazo substituted carbomonocyclic... Specific Chemical Substances § 721.4596 Diazo substituted carbomonocyclic metal complex. (a) Chemical... as a diazo substituted carbomonocyclic metal complex (PMN P-94-1039) is subject to reporting under...

Rare earth element recycling from waste nickel-metal hydride batteries.

Science.gov (United States)

Yang, Xiuli; Zhang, Junwei; Fang, Xihui

2014-08-30

With an increase in number of waste nickel-metal hydride batteries, and because of the importance of rare earth elements, the recycling of rare earth elements is becoming increasingly important. In this paper, we investigate the effects of temperature, hydrochloric acid concentration, and leaching time to optimize leaching conditions and determine leach kinetics. The results indicate that an increase in temperature, hydrochloric acid concentration, and leaching time enhance the leaching rate of rare earth elements. A maximum rare earth elements recovery of 95.16% was achieved at optimal leaching conditions of 70°C, solid/liquid ratio of 1:10, 20% hydrochloric acid concentration, -74μm particle size, and 100min leaching time. The experimental data were best fitted by a chemical reaction-controlled model. The activation energy was 43.98kJ/mol and the reaction order for hydrochloric acid concentration was 0.64. The kinetic equation for the leaching process was found to be: 1-(1-x)(1/3)=A/ρr0[HCl](0.64)exp-439,8008.314Tt. After leaching and filtration, by adding saturated oxalic solution to the filtrate, rare earth element oxalates were obtained. After removing impurities by adding ammonia, filtering, washing with dilute hydrochloric acid, and calcining at 810°C, a final product of 99% pure rare earth oxides was obtained. Copyright © 2014 Elsevier B.V. All rights reserved.

How Does Boiling in the Earth's Crust Influence Metal Speciation and Transport?

Science.gov (United States)

Kam, K.; Lemke, K.

2014-12-01

The presence of large quantities of precious metals, such as gold and copper, near the Earth's surface (upper crust) is commonly attributed to transport in aqueous solution and precipitation upon variations in temperature and pressure. As a consequence, gold exploration is closely linked to solution chemistry, i.e. hydrothermal processes involving aqueous fluids with densities of around unity. However, as crustal fluids buoyantly ascend, boiling produces a coexisting low-density aqueous liquid with fundamentally different physical and chemical properties, and a, most importantly, a high affinity for coinage metals (Heinrich et al., Econ Geol., 1992, 87, 1566). From recent experimental studies of Au (Hurtig and Williams-Jones, 2014, Geochim. Cosmochim. Acta,, 127, 304), we know that metal speciation in this low-density phase differs fundamentally from that observed in bulk solution, clearly, with important implications for Au, and metal speciation in general, transport and ore concentrations processes (these processes would also be operable in industrial geothermal plants given the quite special solvent properties of steam). In brief, this study focuses on the speciation of select metal halides in bulk solution as well as in water vapor, and is driven by our need to understand the solvent properties of around 2.0x109 cubic kilometers of free water (or 2,500 times as much water as stored in all lakes and rivers) present in the Earth's crust. The scope of this study has particular applications in the geothermal and oil industries, as both deal with high temperature low-density aqueous fluids. Understanding how metal halide species behave upon boiling can also provide insight into how metals, such as copper and silver, coat turbine equipment and steam piping in geothermal plants, ultimately rendering these components inoperable. This study will also provide preliminary results from mass spectrometric experiments of transition metal halides, and will be augmented with

Frustration across the periodic table: heterolytic cleavage of dihydrogen by metal complexes.

Science.gov (United States)

Bullock, R Morris; Chambers, Geoffrey M

2017-08-28

This perspective examines frustrated Lewis pairs (FLPs) in the context of heterolytic cleavage of H 2 by transition metal complexes, with an emphasis on molecular complexes bearing an intramolecular Lewis base. FLPs have traditionally been associated with main group compounds, yet many reactions of transition metal complexes support a broader classification of FLPs that includes certain types of transition metal complexes with reactivity resembling main group-based FLPs. This article surveys transition metal complexes that heterolytically cleave H 2 , which vary in the degree that the Lewis pairs within these systems interact. Many of the examples include complexes bearing a pendant amine functioning as the base with the metal functioning as the hydride acceptor. Consideration of transition metal compounds in the context of FLPs can inspire new innovations and improvements in transition metal catalysis.This article is part of the themed issue 'Frustrated Lewis pair chemistry'. © 2017 The Author(s).

Metal nitride cluster as a template to tune the electronic and magnetic properties of rare-earth metal containing endohedral fullerenes

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yang

2013-10-16

Rare-earth metal containing endohedral fullerenes have attracted much attention due to the feasibility of encaging metal atom, atoms or cluster inside of carbon cages. By switching the metal atom or cluster entrapped inside of the carbon cage the physical and chemical properties of the fullerene compounds can be tuned. The understanding of magnetic and electrochemical properties of endohedral fullerenes plays an essential role in fundamental scientific researches and potential applications in materials science. In this thesis, synthesizing novel rare-earth metal containing endohedral fullerene structures, studying the properties of these isolated endohedral fullerenes and the strategies of tuning the electronic and magnetic properties of endohedral fullerenes were introduced. The DC-arc discharging synthesis of different lanthanide metal-based (Ho, Ce and Pr) mixed metal nitride clusterfullerenes was achieved. Those rare-earth metal containing endohedral fullerenes were isolated by multi-step HPLC. The isolated samples were characterized by spectroscopic techniques included UV-vis-NIR, FTIR, Raman, LDI-TOF mass spectrometry, NMR and electrochemistry. The Ho-based mixed metal nitride clusterfullerenes Ho{sub x}M{sub 3-x}N rate at C{sub 80} (M= Sc, Lu, Y; x=1, 2) were synthesized by ''reactive gas atmosphere'' method or ''selective organic solid'' route. The isolated samples were characterized by LDI-TOF mass spectrometry, UV-vis-NIR, FTIR, Raman and NMR spectroscopy. The {sup 13}C NMR spectroscopic studies demonstrated exceptional NMR behaviors that resulted from switching the second metal inside of the mixed metal nitride cluster Ho{sub x}M{sub 3-x}N from Sc to Lu and further to Y. The LnSc{sub 2}N rate at C{sub 80} (Ln= Ce, Pr, Nd, Tb, Dy, Ho, Lu) MMNCFs were characterized by {sup 13}C and {sup 45}Sc NMR study respectively. According to Bleaney's theory and Reilley method, the separation of δ{sup PC} and δ{sup con

Thermodynamic Considerations of Direct Oxygen Removal from Titanium by Utilizing the Deoxidation Capability of Rare Earth Metals

Science.gov (United States)

Okabe, Toru H.; Zheng, Chenyi; Taninouchi, Yu-ki

2018-06-01

Oxygen removal from metallic Ti is extremely difficult and, currently, there is no commercial process for effectively deoxidizing Ti or its alloys. The oxygen concentration in Ti scraps is normally higher than that in virgin metals such as in Ti sponges produced by the Kroll process. When scraps are remelted with virgin metals for producing primary ingots of Ti or its alloys, the amount of scrap that can be used is limited owing to the accumulation of oxygen impurities. Future demands of an increase in Ti production and of mitigating environmental impacts require that the amount of scrap recycled as a feed material of Ti ingots should also increase. Therefore, it is important to develop methods for removing oxygen directly from Ti scraps. In this study, we evaluated the deoxidation limit for β-Ti using Y or light rare earth metals (La, Ce, Pr, or Nd) as a deoxidant. Thermodynamic considerations suggest that extra-low-oxygen Ti, with an oxygen concentration of 100 mass ppm or less can be obtained using a molten salt equilibrating with rare earth metals. The results presented herein also indicate that methods based on molten salt electrolysis for producing rare earth metals can be utilized for effectively and directly deoxidizing Ti scraps.

Mixed Metal Complexes of Isoniazid and Ascorbic Acid: Chelation ...

African Journals Online (AJOL)

HP

these ligands and their metal complexes have revealed the bi-dentate coordination of isoniazid ligand to ... of the drugs on coordination with a metal is enhanced ..... James, O.O., Nwinyi, C.O. and. Allensela, M.A. (2008). Cobalt(II) complexes of mixed antibiotics: Synthesis,. Characterization, antimicrobial potential and their.

Novel 2D or 3D alkaline-earth metal sulfonate-phosphonates based on [O 3S-C 2H 4-PO 3H] 2- ligand

Science.gov (United States)

Du, Zi-Yi; Wen, He-Rui; Xie, Yong-Rong

2008-11-01

Three novel alkaline-earth metal sulfonate-phosphonates based on [O 3S-C 2H 4-PO 3H] 2- ligand, namely, [Ca(O 3SC 2H 4PO 3H)(H 2O) 2] ( 1), [Sr(O 3SC 2H 4PO 3H)] ( 2) and [Ba 2(O 3SC 2H 4PO 3H) 2] ( 3), have been synthesized by hydrothermal reactions. They represent the first structurally characterized alkaline-earth metal complexes of phosphonic acid attached with a sulfonate group. The structure of compound 1 features a 2D layer based on 1D chains of [Ca 2(PO 3) 2] bridged by -CH 2-CH 2-SO 3- groups. Compounds 2 and 3 show pillar-layer architecture based on two different inorganic layers linked by -CH 2-CH 2- groups. The inorganic layer in compound 2 features a 1D chain of edge-sharing SrO 8 polyhedra whereas that in compound 3 features an edge-sharing Ba 2O 14 di-polyhedral unit which is further corner-shared with four neighboring ones. The [O 3S-C 2H 4-PO 3H] 2- ligand shows diverse coordination modes in the three alkaline-earth metal sulfonate-phosphonates.

Semiempirical calculation of van der Waals coefficients for alkali-metal and alkaline-earth-metal atoms

International Nuclear Information System (INIS)

Mitroy, J.; Bromley, M.W.J.

2003-01-01

The van der Waals coefficients, C 6 , C 8 , and C 10 for the alkali-metal (Li, Na, K, and Rb) and alkaline-earth-metal (Be, Mg, Ca, and Sr) atoms are estimated by a combination of ab initio and semiempirical methods. Polarizabilities and atom-wall coefficients are given as a diagnostic check, and the lowest order nonadiabatic dispersion coefficient, D 8 and the three-body coefficient, C 9 are also presented. The dispersion coefficients are in agreement with the available relativistic many-body perturbation theory calculations. The contribution from the core was included by using constrained sum rules involving the core polarizability and Hartree-Fock expectation values to estimate the f-value distribution

Rare-earth element geochemistry in the Luanga Mafic-Ultramafic Complex, Para

International Nuclear Information System (INIS)

Suita, M.T.F.; Nilson, A.A.

1989-01-01

Six whole-rock samples (harzburgite, orthopyroxenic and norite) of the Luanga Mafic-Ultramafic Complex (Para) were analysed for rare-earth elements (REE) through plasma spectrometry. The Luanga Complex is a deformed and metamorphosed layered mafic-ultramafic body of Archaean age. The Complex underwent medium-grade metamorphism in three stages. The first stage (medium grade) involved local formation of tremolite and reduction of Ca content in plagioclase. The second stage (low grade) consisted of serpentinization of amphibole or ortopyroxene forming bastile and generation of albite + epidote + white mica + actinolite from plagioclase. The third stage involved renewed serpentinization and/or talcification of pre-existing minerals (including serpentine) along fracture and fault surfaces. The analysed rocks display light rare-earth element (LREE) enrichment up to sixty times the composition of the Leedly chondrite and La/Yb ratios from 6.2 to 20.0 they are low in medium rare-earth elements (MREE), displaying discrete to strong negative Eu anomaly even in plagioclase cumulates and are slightly enriched in heavy rare-earth elements (HREE), usually higher than chondrite values. The low MREE area related to the occurrence of orthopyroxene (bronzite) in a way similar to the pattern of alpine periodotites, while HREE enrichment is compatible with the presence of bronzite and Mg-olivine, probably an inherited igneous feature. (author) [pt

Red-emitting alkaline-earth rare-earth pentaoxometallates powders ...

Indian Academy of Sciences (India)

Moisture-insensitive metal carboxylates that are mostly liquids at room temperature have been first applied to ... alkaline-earth ion, or possibly even a rare-earth ion and alkali metal ... sion spectra of the powders were recorded on a fluorescent.

Electron states in thulium and other rare-earth metals

International Nuclear Information System (INIS)

Strange, P.; Fairbairn, W.M.; Lee, P.M.

1983-01-01

The LMTO method has been applied to calculate band structures for the heavier rare-earth metals. The calculations are relativistic. Thulium in particular has been considered, where a frozen core approximation is used, and the outer electrons are treated selfconsistently. Problems associated with the localisation and interactions of the 4f electrons are discussed. Teh comparisons between experimental data and calculated quantities are encouraging, but more data on high-purity single crystals would be helpful. (author)

Interaction of copper metallization with rare-earth metals and silicides

International Nuclear Information System (INIS)

Molnar, G. L.; Peto, G.; Zsoldos, E.; Horvath, Z. E.

2001-01-01

Solid-phase reactions of copper films with underlying gadolinium, erbium, and erbium - silicide layers on Si(100) substrates were investigated. For the phase analysis, x-ray diffraction and cross-sectional transmission electron microscopy were used. In the case of Cu/Gd/Si(100), an orthorhombic GdSi 2 formed, and, at higher temperatures, copper aggregated into islands. Annealed Cu/Er/Si(100) samples resulted in a hexagonal Er 5 Si 3 phase. In the Cu/ErSi 2-x /Si system, the copper catalyzes the transformation of the highly oriented hexagonal ErSi 2-x phase into hexagonal Er 5 Si 3 . Diverse phase developments of the samples with Gd and Er are based on reactivity differences of the two rare-earth metals. [copyright] 2001 American Institute of Physics

Effects of complexing compounds on sorption of metal ions to cement

Energy Technology Data Exchange (ETDEWEB)

Loevgren, Lars [Umeaa Univ. (Sweden). Inorganic chemistry

2005-12-15

This present report is a literature review addressing the effects of complexing ligands on the sorption of radionuclides to solid materials of importance for repositories of radioactive waste. Focus is put on laboratory studies of metal ion adsorption to cement in presence of chelating agents under strongly alkaline conditions. As background information, metal sorption to different mineral and cement phases in ligand free systems is described. Furthermore, surface complexation model (SCM) theories are introduced. According to surface complexation theories these interactions occur at specific binding sites at the particle/water interface. Adsorption of cationic metals is stronger at high pH, and the adsorption of anions occurs preferentially at low pH. The adsorption of ions to mineral surfaces is a result of both chemical bonding and electrostatic attraction between the ions and charged mineral surfaces. By combining uptake data with spectroscopic information the sorption can be explained on a molecular level by structurally sound surface complexation models. Most of the metal sorption studies reviewed are dealing with minerals exhibiting oxygen atoms at their surfaces, mainly oxides of Fe(II,III) and Al(III), and aluminosilicates. Investigations of radionuclides are focused on clay minerals, above all montmorillonite and illite. Which mechanism that is governing the metal ion adsorption to a given mineral is to a large extent depending on the metal adsorbed. For instance, sorption of Ni to montmorillonite can occur by formation of inner-sphere mononuclear surface complexes located at the edges of montmorillonite platelets and by formation of a Ni phyllosilicate phase parallel to montmorillonite layers. Also metal uptake to cement materials can occur by different mechanisms. Cationic metals can both be attached to cement (calcium silicate hydrate, CSH) and hardened cement paste (HCP) by formation of inner-sphere complexes at specific surface sites and by

Voltage Control of Rare-Earth Magnetic Moments at the Magnetic-Insulator-Metal Interface

Science.gov (United States)

Leon, Alejandro O.; Cahaya, Adam B.; Bauer, Gerrit E. W.

2018-01-01

The large spin-orbit interaction in the lanthanides implies a strong coupling between their internal charge and spin degrees of freedom. We formulate the coupling between the voltage and the local magnetic moments of rare-earth atoms with a partially filled 4 f shell at the interface between an insulator and a metal. The rare-earth-mediated torques allow the power-efficient control of spintronic devices by electric-field-induced ferromagnetic resonance and magnetization switching.

On halide derivatives of rare-earth metal(III) oxidomolybdates(VI) and -tungstates(VI)

International Nuclear Information System (INIS)

Schleid, Thomas; Hartenbach, Ingo

2016-01-01

Halide derivatives of rare-earth metal(III) oxidomolybdates(VI) have been investigated comprehensively over the last decade comprising the halogens fluorine, chlorine, and bromine. Iodide-containing compounds are so far unknown. The simple composition REXMoO 4 (RE=rare-earth element, X=halogen) is realized for X=F almost throughout the complete lanthanide series as well as for yttrium. While ytterbium and lutetium do not form any fluoride derivative, for lanthanum, only a fluoride-deprived compound with the formula La 3 FMo 4 O 16 is realized. Moreover, molybdenum-rich compounds with the formula REXMo 2 O 7 are also known for yttrium and the smaller lanthanoids. For X=Cl the composition REClMoO 4 is known for yttrium and the whole lanthanide series, although, four different structure types were identified. Almost the same holds for X=Br, however, only two different structure types are realized in this class of compounds. In the case of halide derivatives of rare-earth metal(III) oxidotungstates(VI) the composition REXWO 4 is found for chlorides and bromides only, so far. Due to the similar size of Mo 6+ and W 6+ cations, the structures found for the tungstates are basically the same as for the molybdates. With the larger lanthanides, the representatives for both chloride and bromide derivates exhibit similar structural motifs as seen in the molybdates, however, the crystal structure cannot be determined reliably. In case of the smaller lanthanoids, the chloride derivatives are isostructural with the respective molybdates, although the existence ranges differ slightly. The same is true for rare-earth metal(III) bromide oxidotungstates(VI).

Homogeneous Catalysis with Metal Complexes Fundamentals and Applications

CERN Document Server

Duca, Gheorghe

2012-01-01

The book about homogeneous catalysis with metal complexes deals with the description of the reductive-oxidative, metal complexes  in a liquid phase (in polar solvents, mainly in water, and less in nonpolar solvents). The exceptional importance of the redox processes in chemical systems, in the reactions occuring in living organisms, the environmental processes, atmosphere, water, soil, and in industrial technologies (especially in food-processing industries) is discussed. The detailed practical aspects of the established regularities are explained for solving the specific practical tasks in various fields of industrial chemistry, biochemistry, medicine, analytical chemistry and ecological chemistry. The main scope of the book is the survey and systematization of the latest advances in homogeneous catalysis with metal complexes. It gives an overview of the research results and practical experience accumulated by the author during the last decade.

Lability of nanoparticulate metal complexes in electrochemical speciation analysis

DEFF Research Database (Denmark)

van Leeuwen, Herman P.; Town, Raewyn M.

2016-01-01

Lability concepts are elaborated for metal complexes with soft (3D) and hard (2D) aqueous nanoparticles. In the presence of a non-equilibrium sensor, e.g. a voltammetric electrode, the notion of lability for nanoparticulate metal complexes, M-NP, reflects the ability of the M-NP to maintain...... equilibrium with the reduced concentration of the electroactive free M2+ in its diffusion layer. Since the metal ion binding sites are confined to the NP body, the conventional reaction layer in the form of a layer adjacent to the electrode surface is immaterial. Instead an intraparticulate reaction zone may...... of the electrochemical technique is crucial in the lability towards the electrode surface. In contrast, for nanoparticulate complexes it is the dynamics of the exchange of the electroactive metal ion with the surrounding medium that governs the effective lability towards the electrode surface....

Kinetics of the reactions of hydrated electrons with metal complexes

International Nuclear Information System (INIS)

Korsse, J.

1983-01-01

The reactivity of the hydrated electron towards metal complexes is considered. Experiments are described involving metal EDTA and similar complexes. The metal ions studied are mainly Ni 2+ , Co 2+ and Cu 2+ . Rates of the reactions of the complexes with e - (aq) were measured using the pulse radiolysis technique. It is shown that the reactions of e - (aq) with the copper complexes display unusually small kinetic salt effects. The results suggest long-range electron transfer by tunneling. A tunneling model is presented and the experimental results are discussed in terms of this model. Results of approximate molecular orbital calculations of some redox potentials are given, for EDTA chelates as well as for series of hexacyano and hexaquo complexes. Finally, equilibrium constants for the formation of ternary complexes are reported. (Auth./G.J.P.)

The alkali and alkaline earth metal doped ZnO nanotubes: DFT studies

International Nuclear Information System (INIS)

Peyghan, Ali Ahmadi; Noei, Maziar

2014-01-01

Doping of several alkali and alkaline earth metals into sidewall of an armchair ZnO nanotube has been investigated by employing the density functional theory in terms of energetic, geometric, and electronic properties. It has been found that doping processes of the alkali and alkaline metals are endothermic and exothermic, respectively. Based on the results, contrary to the alkaline metal doping, the electronic properties of the tube are much more sensitive to alkali metal doping so that it is transformed from intrinsic semiconductor with HOMO–LUMO energy gap of 3.77 eV to an extrinsic semiconductor with the energy gap of ∼1.11–1.95 eV. The doping of alkali and alkaline metals increases and decreases the work function of the tube, respectively, which may influence the electron emission from the tube surface

Infrared Spectroscopy of Metal Ion Complexes: Models for Metal Ligand Interactions and Solvation

Science.gov (United States)

Duncan, Michael

2006-03-01

Weakly bound complexes of the form M^+-Lx (M=Fe, Ni, Co, etc.; L=CO2, C2H2, H2O, benzene, N2) are prepared in supersonic molecular beams by laser vaporization in a pulsed-nozzle cluster source. These species are mass analyzed and size-selected in a reflectron time-of-flight mass spectrometer. Clusters are photodissociated at infrared wavelengths with a Nd:YAG pumped infrared optical parametric oscillator/amplifier (OPO/OPA) laser or with a tunable infrared free-electron laser. M^+-(CO2)x complexes absorb near the free CO2 asymmetric stretch near 2349 cm-1 but with an interesting size dependent variation in the resonances. Small clusters have blue-shifted resonances, while larger complexes have additional bands due to surface CO2 molecules not attached to the metal. M^+(C2H2)n complexes absorb near the C-H stretches in acetylene, but resonances in metal complexes are red-shifted with repect to the isolated molecule. Ni^+ and Co^+ complexes with acetylene undergo intracluster cyclization reactions to form cyclobutadiene. Transition metal water complexes are studied in the O-H stretch region, and partial rotational structure can be measured. M^+(benzene) and M^+(benzene)2 ions (M=V, Ti, Al) represent half-sandwich and sandwich species, whose spectra are measured near the free benzene modes. These new IR spectra and their assignments will be discussed as well as other new IR spectra for similar complexes.

Transition Metal Complexes and Catalysis

Indian Academy of Sciences (India)

approaches towards the study of bonding in transition metal complexes. Despite .... industrial scale reactions for the production of organic compounds using transition ..... It has found several applications as an engineering thermoplastic. .... and processes of interest to the company, that is, applied research. It is this very ...

Theoretical studies of transition metal complexes with nitriles and isocyanides

International Nuclear Information System (INIS)

Kuznetsov, Maksim L

2002-01-01

Theoretical studies of transition metal complexes with nitriles and isocyanides are reviewed. The electronic structures and the nature of coordination bonds in these complexes are discussed. The correlation between the electronic structures of transition metal complexes with nitriles and isocyanides and their structural properties, spectroscopic characteristics, and reactivities are considered. The bibliography includes 121 references.

Determination of stability constants of aminoglycoside antibiotics with their metal complexes

Science.gov (United States)

Tiwow, Vanny M. A.

2014-03-01

One group of aminoglycoside antibiotics contains aminosugars. The aminosugar neomycin B with its derivate product neamine (2-Deoxy-4-0-(2,6-diamino-2,6-dideoxy-α-D-glucopyranosyl)-D-Streptamine) was identified as a free ligands and metal complexes. In particular, the stability constants of metal complexes by potentiometric titration techniques were investigated. Our previous study had determined the acid dissociation constants of these aminosugars with few metal complexes in fair depth. In this work, the complexation of two pyridine-containing amino alcohols and an amino sugar (neamine) have been measured potentiometrically. For instance, the stability constant of copper(II) complexation were determine and the model system generated an excellent fit. Stability constants with several metals have been determined and will be reported.

Enhanced Photocatalytic Activity of Rare Earth Metal (Nd and Gd doped ZnO Nanostructures

Directory of Open Access Journals (Sweden)

P. Logamani

2017-06-01

Full Text Available Presence of harmful organic pollutants in wastewater effluents causes serious environmental problems and therefore purification of this contaminated water by a cost effective treatment method is one of the most important issue which is in urgent need of scientific research. One such promising treatment technique uses semiconductor photocatalyst for the reduction of recalcitrant pollutants in water. In the present work, rare earth metals (Nd and Gd doped ZnO nanostructured photocatalyst have been synthesized by wet chemical method. The prepared samples were characterized by X-ray diffraction (XRD, Field Emission Scanning Electron Microscopy (FESEM and energy dispersive X-ray spectroscopy (EDS. The XRD results showed that the prepared samples were well crystalline with hexagonal Wurtzite structure. The results of EDS revealed that rare earth elements were doped into ZnO structure. The effect of rare earth dopant on morphology and photocatalytic degradation properties of the prepared samples were studied and discussed. The results revealed that the rare earth metal doped ZnO samples showed enhanced visible light photocatalytic activity for the degradation of methylene blue dye than pure nano ZnO photocatalyst.

Capturing near-Earth asteroids around Earth

Science.gov (United States)

Hasnain, Zaki; Lamb, Christopher A.; Ross, Shane D.

2012-12-01

The list of detected near-Earth asteroids (NEAs) is constantly growing. NEAs are likely targets for resources to support space industrialization, as they may be the least expensive source of certain needed raw materials. The limited supply of precious metals and semiconducting elements on Earth may be supplemented or even replaced by the reserves floating in the form of asteroids around the solar system. Precious metals make up a significant fraction NEAs by mass, and even one metallic asteroid of ˜1km size and fair enrichment in platinum-group metals would contain twice the tonnage of such metals already harvested on Earth. There are ˜1000 NEAs with a diameter of greater than 1 km. Capturing these asteroids around the Earth would expand the mining industry into an entirely new dimension. Having such resources within easy reach in Earth's orbit could provide an off-world environmentally friendly remedy for impending terrestrial shortages, especially given the need for raw materials in developing nations. In this paper, we develop and implement a conceptually simple algorithm to determine trajectory characteristics necessary to move NEAs into capture orbits around the Earth. Altered trajectories of asteroids are calculated using an ephemeris model. Only asteroids of eccentricity less than 0.1 have been studied and the model is restricted to the ecliptic plane for simplicity. We constrain the time of retrieval to be 10 years or less, based on considerations of the time to return on investment. For the heliocentric phase, constant acceleration is assumed. The acceleration required for transporting these asteroids from their undisturbed orbits to the sphere of influence of the Earth is the primary output, along with the impulse or acceleration necessary to effect capture to a bound orbit once the Earth's sphere of influence is reached. The initial guess for the constant acceleration is provided by a new estimation method, similar in spirit to Edelbaum's. Based on the

METAL COMPLEXES OF SALICYLHYDROXAMIC ACID AND 1,10 ...

African Journals Online (AJOL)

Preferred Customer

Metal complexes which are formed in biological systems between a ligand and a metal ion are in dynamic ... In a continuation of our research work oriented towards studying the .... Antimicrobial activity techniques. Preparation of test samples.

Alkylation and arylation of alkenes by transition metal complexes

International Nuclear Information System (INIS)

Volkova, L.G.; Levitin, I.Ya.; Vol'pin, M.E.

1975-01-01

In this paper are reviewed methods of alkylation and irylation of unsaturated compounds with complexes of transition metals (Rh, Pd). Analysis of alkylation and arylation of olefines with organic derivatives of transition metals, obtained as a result of exchange reactions between organic compounds of transition metals and salts of metals of the 8th group of the periodic system, allows a conclusion as to the wide possibilities of these reactions in the synthesis of various derivatives of unsaturated compounds. In all the reactions under consideration, intermediate formation of sigma-complexes is assumed. Also considered are alkylation and arylation of olefines with organic derivatives of halogens in the presence of compounds of metals of the 8th group of the periodic system, as well as arylation of olefines with aromatic compounds in the presence of salts of transition metals

Recovery of fluorine, uranium, and rare earth metal values from phosphoric acid by-product brine raffinate

International Nuclear Information System (INIS)

Wamser, C.A.; Bruen, C.P.

1976-01-01

A method for recovering substantially all of the fluorine and uranium values and at least 90 percent of the rare earth metal values from brine raffinate obtained as by-product in the production of phosphoric acid by the hydrochloric acid decomposition of tricalcium phosphate minerals is described. A basically reacting compound is added to the brine raffinate to effect a pH 9 or greater, whereby fluorine, uranium and rare earth metal values are simultaneously precipitated. These values may then be separately recovered from the precipitate by known processes

Colour interceptions, thermal stability and surface morphology of polyester metal complexes

International Nuclear Information System (INIS)

Zohdy, M.H.

2005-01-01

Chelating copolymers via grafting of acrylic acid (AAc) and acrylamide (AAm/AAc) comonomer mixture onto polyester micro fiber fabrics (PETMF) using gamma-radiation technique were prepared. The prepared graft chains (PETMF-g-AAc) and (PETMF-g-PAAc/PAAm) acted as chelating sites for some selected transition metal ions. The prepared graft copolymers and their metal complexes were characterized using thermogravimetric analysis (TGA), colour parameters and surface morphology measurements. The colour interception and strength measurements showed that the metal complexation is homogeneously distributed. The results showed that the thermal stability of PETMF was improved after graft copolymerization and metal complexes. Moreover, the degree of grafting enhanced the thermal stability values of the grafted and complexed copolymers up to 25% of magnitude, on the other hand the activation energy of the grafted-copolymer with acrylic acid increased up to 80%. The SEM observation gives further supports to the homogenous distribution of grafting and metal complexation

Optimization of film synthesized rare earth transition metal permanent magnet systems

International Nuclear Information System (INIS)

Cadieu, F.J.

1990-01-01

This report reviews work on the optimization of film synthesized rare earth transition metal permanent magnet systems. Topics include: high coercivity in Sm-Fe-Ti-V, Sm-Fe-V, and two element systems; ThMn 12 type pseudobinary SmFe 12 - X T X ; and sputter process control for the synthesis of precisely textured RE-TM magnetic films. (JL)

Preparation and Property of Acrylic Acid Rare Earth Complex and Its Hydrosilylation

Institute of Scientific and Technical Information of China (English)

Zhang Ming; Chen Haiyan; Chen Xiaosong; Dai Shaojun; Inoue Shinich; Okamoto Hiroshi

2004-01-01

Acrylic acid rare earth complex was prepared. Its chemical composition was determined by chemical and elemental analysis, and its structure as well as properties was characterized using IR, Fluorescence and UV spectrum, and its solubility was also investigated. Meanwhile a kind of elastic functional polymer with rare earth units in the side chains was produced. It is confirmed by IR spectrum that the Si-H bonds really react with acrylic acid rare earth.

THE THEORY OF DEVELOPMENT OF SUPPORTED METAL-COMPLEX CATALYSTS

Directory of Open Access Journals (Sweden)

T. L. Rakitskaya

2015-06-01

Full Text Available Some results of the investigations for the purpose of development of supported metal-complex catalysts for phosphine and carbon monoxide oxidation as well as for ozone decomposition are summarized. The activity of such catalysts has been found to depend not only on a nature of a central atom and ligands but also on a nature of supports. The theoretical model explaining mechanisms of surface complex formation taking into account the influence of physicochemical and structural-adsorption properties of the supports (SiO2, Al2O3, carbon materials, zeolites, dispersed silicas, lamellar aluminosilicates, etc. has been proposed. For quantitative description of the support effect, such a thermodynamic parameter as the adsorbed water activity assignable with the help of water vapor adsorption isotherms has been introduced. Successive stability constants of the surface metal complexes have been calculated by the kinetic method and, hence, compositions and partial catalytic activity of the latter have been determined. Taking into account the competitive adsorption of metal ions on the supports, some schemes of formation of surface bimetallic complexes have been suggested. The compositions of the supported metal-complex catalysts have been optimized to meet requirements of their use in respirators and plants for air purification from foregoing gaseous toxicants.

Properties- and applications of quasicrystals and complex metallic alloys.

Science.gov (United States)

Dubois, Jean-Marie

2012-10-21

This article aims at an account of what is known about the potential for applications of quasicrystals and related compounds, the so-called family of Complex Metallic Alloys (CMAs‡). Attention is focused at aluminium-based CMAs, which comprise a large number of crystalline compounds and quasicrystals made of aluminium alloyed with transition metals (like Fe or Cu) or normal metals like Mg. Depending on composition, the structural complexity varies from a few atoms per unit cell up to thousands of atoms. Quasicrystals appear then as CMAs of ultimate complexity and exhibit a lattice that shows no periodicity anymore in the usual 3-dimensional space. Properties change dramatically with lattice complexity and turn the metal-type behaviour of simple Al-based crystals into a far more complex behaviour, with a fingerprint of semi-conductors that may be exploited in various applications, potential or realised. An account of the ones known to the author is given in the light of the relevant properties, namely light absorption, reduced adhesion and friction, heat insulation, reinforcement of composites for mechanical devices, and few more exotic ones. The role played by the search for applications of quasicrystals in the development of the field is briefly addressed in the concluding section.

Tracking environmental impacts in global product chains - Rare Earth Metals and other critical metals used in the cleantech industry

Energy Technology Data Exchange (ETDEWEB)

Pathan, A.; Schilli, A.; Johansson, J.; Vehvilaeinen, I.; Larsson, A.; Hutter, J.

2013-03-15

Metals form a central part of the global economy, but their extraction and supply are linked to several environmental and social concerns. This study aims to create a picture of the supply chain of Rare Earth Metals (REMs) and other critical metals used in the clean technology (cleantech) sectors of electric vehicles and solar panels. The study examines how Nordic cleantech companies are aware and acting on the challenges related to the lifecycle of these metals and what are the potentials to minimise environmental and social impacts. Recommendations of the study can be summarised as three initiatives: establishment of an awareness platform and roundtable initiative (short-term), research and information gathering (mid-term), and development of closed-loop solutions (long-term). (Author)

Metallothermic reduction of rare earth oxides

International Nuclear Information System (INIS)

Sharma, R.A.

1986-01-01

Rare earth oxides can be reduced to rare earth metals by a novel, high yield, metallothermic process. The oxides are dispersed in a suitable, molten, calcium chloride bath along with sodium metal. The sodium reacts with the calcium chloride to produce calcium metal which reduces the rare earth oxides to rare earth metals. The metals are collected in a discrete layer in the reaction vessel

Preservation of NOM-metal complexes in a modern hyperalkaline stalagmite: Implications for speleothem trace element geochemistry

Science.gov (United States)

Hartland, Adam; Fairchild, Ian J.; Müller, Wolfgang; Dominguez-Villar, David

2014-03-01

We report the first quantitative study of the capture of colloidal natural organic matter (NOM) and NOM-complexed trace metals (V, Co, Cu, Ni) in speleothems. This study combines published NOM-metal dripwater speciation measurements with high-resolution laser ablation ICPMS (LA-ICPMS) and sub-annual stable isotope ratio (δ18O and δ13C), fluorescence and total organic carbon (TOC) analyses of a fast-growing hyperalkaline stalagmite (pH ˜11) from Poole’s Cavern, Derbyshire UK, which formed between 1997 and 2008 AD. We suggest that the findings reported here elucidate trace element variations arising from colloidal transport and calcite precipitation rate changes observed in multiple, natural speleothems deposited at ca. pH 7-8. We find that NOM-metal(aq) complexes on the boundary between colloidal and dissolved (˜1 nm diameter) show an annual cyclicity which is inversely correlated with the alkaline earth metals and is explained by calcite precipitation rate changes (as recorded by kinetically-fractionated stable isotopes). This relates to the strength of the NOM-metal complexation reaction, resulting in very strongly bound metals (Co in this system) essentially recording NOM co-precipitation (ternary complexation). More specifically, empirical partition coefficient (Kd) values between surface-reactive metals (V, Co, Cu, Ni) [expressed as ratio of trace element to Ca ratios in calcite and in solution] arise from variations in the ‘free’ fraction of total metal in aqueous solution (fm). Hence, differences in the preservation of each metal in calcite can be explained quantitatively by their complexation behaviour with aqueous NOM. Differences between inorganic Kd values and field measurements for metal partitioning into calcite occur where [free metal] ≪ [total metal] due to complexation reactions between metals and organic ligands (and potentially inorganic colloids). It follows that where fm ≈ 0, apparent inorganic Kd app values are also ≈0, but the

Targeting heavy rare earth elements in carbonatite complexes

Science.gov (United States)

Broom-Fendley, S.; Wall, F.; Gunn, A. G.; Dowman, E.

2012-04-01

The world's main sources of the rare earth elements (REE) are concentrated in carbonatite complexes. These have the advantages of high grade and tonnage, combined with low thorium contents, yet they are generally enriched in light rare earths (LREE). The heavy rare earths (HREE, which include Eu-Lu and Y) are more highly sought after because of their role in new and green technologies. HREE are predominantly extracted from ion-adsorption clays in China. These are small, low grade deposits, which are often illegally mined by artisans. Increased government control, environmental legislation and local demand for REE in China have led to high prices and global concerns about the security of supply of the HREE. Alternative sources of the HREE are poorly documented. We present a review of such targets, including: (1) 'abnormal' carbonatites; (2) areas around LREE-rich complexes such as breccia, fenite and latter stage veins; and (3) weathered carbonatites. At Lofdal, Namibia, carbonatite dykes contain xenotime-(Y) together with LREE minerals. The original chemistry of the carbonatite magma, coupled with late-stage magma and fluid evolution, seem to be controlling factors [1, 2]. The Khibina carbonatite, Kola Peninsula, Russia, is an example of where early LREE carbonatites become increasing HREE-enriched as magmas evolve to carbo-hydrothermal fluids [3]. Around carbonatite complexes in Malawi HREE enrichment can be found in breccia and in fenite. Breccia around Songwe shows areas with high Y/La ratios within the matrix caused by narrow zones of xenotime enrichment. Fenite around Kangankunde and Chilwa Island has higher HREE:LREE ratios than the carbonatite [4]. At weathered complexes, such as at Mount Weld in Western Australia, changes in both HREE concentration and LREE:HREE ratios are observed. In currently unworked sections of the deposit, the HREE mineral churchite (YPO4.H2O) has formed concentrations due to groundwater flow [5]. These areas of enrichment are

Distribution behavior of uranium, neptunium, rare-earth elements (Y, La, Ce, Nd, Sm, Eu, Gd) and alkaline-earth metals (Sr,Ba) between molten LiCl-KCl eutectic salt and liquid cadmium or bismuth

International Nuclear Information System (INIS)

Kurata, M.; Sakamura, Y.; Hijikata, T.; Kinoshita, K.

1995-01-01

Distribution coefficients of uranium neptunium, eight rare-earth elements (Y, La, Ce, Pr, Nd, Sm, Eu and Gd) and two alkaline-earth metals (Sr and Ba) between molten LiCl-KCl eutectic salt and either liquid cadmium or bismuth were measured at 773 K. Separation factors of trivalent rare-earth elements to uranium or neptunium in the LiCl-KCl/Bi system were by one or two orders of magnitude larger than those in the LiCl-KCl/Cd system. On the contrary, the separation factors of alkaline-earth metals and divalent rare-earth elements to trivalent rare-earth elements were by one or two orders of magnitude smaller in the LiCl-KCl/Bi system. (orig.)

Pharmacologically significant tetraaza macrocyclic metal complexes ...

Indian Academy of Sciences (India)

MOHAMMAD SHAKIR

2017-11-22

Nov 22, 2017 ... structural biological models.6 Hence, biological prop- erties of ... poor water solubility, exhibits intrinsic resistance and ..... pdb). The metal complex files were drawn using. ChemDraw (MM2) and their energies were minimized.

Supramolecular structures constructed from three novel rare earth ...

Indian Academy of Sciences (India)

Supramolecular structures constructed from three novel rare earth metal complexes. HUAZE DONGa,∗, XIAOJUN FENGb,∗, XIA LIUc, BIN ZHENGa, JIANHONG BIa, YAN XUEa,. SHAOHUA GOUd and YANPING WANGa. aDepartment of Chemistry and Chemical Engineering, Hefei Normal University, Hefei 230061, China.

Revisited: the conception of lability of metal complexes

NARCIS (Netherlands)

Leeuwen, van H.P.

2001-01-01

Starting from the original reaction layer concept, the voltammetric properties of electroinactive metal complexes are critically reviewed in terms of their finite rates of dissociation into electroactive free metal ions. The limiting conditions for the reaction layer-based flux expressions are made

Basic deuteroexchange in transition metal complexes with nitrogen-containing aromatic heterocycles

International Nuclear Information System (INIS)

Tupitsyn, I.F.

1986-01-01

Kinetics of deuteroexchange in the methyl group of nitrate complexes of a metal - nickel (2) - with different methyl-substituted aromatic heterocycles and isostructural complexes of a ligand - 2 - methyl quinoline - with different central metal atoms (Mn(2), Ni(2), Cu(2), Zn(2)) is studied. Series for influence of ligand structure on deuteroexchange rate in complexes doesn't correspond qualitatively to series for deuteroexchange rate increase in noncoordinated ligands. Deuteroexchange rate is weakly subjected to influence of exchange in metal-complexing agent. Deuteroexchange mechanism is suggested and discussed. According to this mechanism the structure developed in the course of the exchange process with electron density transfer from the heterocyclic ligand to a metal ion is a transition state of the reaction

Preparation of rare earth and other metal alloys containing aluminum and silicon

International Nuclear Information System (INIS)

Mitchell, A.; Goldsmith, J.R.; Gray, M.

1981-01-01

A method is provided for making alloys of aluminum and silicon with a third metal which may be a rare earth or a member of groups 4b, 5b, or 6b of the periodic table. The flux system CaF 2 -CaO-Al 2 O 3 is used as a solvent to provide a reactive medium for the alloy-forming reactions. Aluminum is supplied as a reducing agent, and silicon is added as a sink for the alloying metal. The resulting alloy may be used in steels. (L.L.)

Antiferromagnetic coupling between rare earth ions and semiquinones in a series of 1:1 complexes.

Science.gov (United States)

Caneschi, Andrea; Dei, Andrea; Gatteschi, Dante; Poussereau, Sandrine; Sorace, Lorenzo

2004-04-07

We use the strategy of diamagnetic substitution for obtaining information on the crystal field effects in paramagnetic rare earth ions using the homologous series of compounds with the diamagnetic tropolonato ligand, Ln(Trp)(HBPz(3))(2), and the paramagnetic semiquinone ligand, Ln(DTBSQ)(HBPz(3))(2), (DTBSQ = 3,5-di-tert-butylsemiquinonato, Trp = tropolonate, HBPz(3)= hydrotrispyrazolylborate) for Ln = Sm(iii), Eu(iii), Gd(iii), Tb(iii), Dy(iii), Ho(iii), Er(iii) or Yb(iii). The X-ray crystal structure of a new form of tropolonate derivative is presented, which shows, as expected, a marked similarity with the structure of the semiquinonate derivative. The Ln(Trp)(HBPz(3))(2) derivatives were then used as a reference for the qualitative determination of crystal field effects in the exchange coupled semiquinone derivatives. Through magnetisation and susceptibility measurements this empirical diamagnetic substitution method evidenced for Er(iii), Tb(iii), Dy(iii) and Yb(iii) derivatives a dominating antiferromagnetic coupling. The increased antiferromagnetic contribution compared to other radical-rare earth metal complexes formed by nitronyl nitroxide ligands may be related to the increased donor strength of the semiquinone ligand.

Optimization of film synthesized rare earth transition metal permanent magnet systems

International Nuclear Information System (INIS)

Cadieu, F.J.

1992-01-01

Progress is reported in three areas: high coercivity Sm-Fe-Ti-V, Sm-Fe-Zr, and two element Sm-Fe Sm 5 (Fe,T) 17 type crystalline phases; ThMn 12 type pseudobinary SmFe 12-x T x (0≤x≤1.5); and sputter process control for the synthesis of precisely textured rare earth-transition metal magnetic films

The role of metal complexes in nuclear reactor decontamination

Energy Technology Data Exchange (ETDEWEB)

Prince, A.A.M.; Raghavan, P.S.; Gopalan, R. [Madras Christian College, Tambaram, Chennai (India); Velmurugan, S.; Narasimhan, S.V. [Bhabha Atomic Research Center (BARC) (IN). Water and Steam Chemistry Lab. (WSCL)

2006-07-15

Chemical decontamination is the process of removal of radioactivity from corrosion products formed on structural materials in the nuclear reactors. These corrosion products cause problems for the operation and maintenance of the plants. Removal of the radioactive contaminants can be achieved by dissolving the oxide from the system surface using organic complexing agents in low concentrations known as dilute chemical decontamination (DCD) formulations. These organic complexing agents attack the oxide surface and form metal complexes, which further accelerate the dissolution process. The stability of the complexes plays an important role in dissolving the radioactive contaminated oxides. In addition, the DCD process is operated through ion exchange resins for the removal of the dissolved metal ions and radioactive nuclides. In the present study, the kinetics of dissolution of various model corrosion products such as magnetite (Fe{sub 3}O{sub 4}), hematite ({alpha}-Fe{sub 2}O{sub 3}) and maghemite ({gamma}-Fe{sub 2}O{sub 3}) have been studied in the presence of complexing agents such as ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), hydroxyethylethylenediaminepentaacetic acid (HEEDTA), and 2,6 pyridinedicarboxylic acid (PDCA). The reductive roles of metal complexes and organic reducing agents are discussed. (orig.)

Intraparticulate Metal Speciation Analysis of Soft Complexing Nanoparticles. The Intrinsic Chemical Heterogeneity of Metal-Humic Acid Complexes

DEFF Research Database (Denmark)

Town, R. M.; van Leeuwen, Herman P.

2016-01-01

ion condensation potential for higher valency counterions within the intraparticulate double layer zone of the soft NP. The approach offers new insights into the intrinsic heterogeneity of the HA. complexes, as revealed by the intraparticulate speciation as a function of the true degree of inner......-sphere complexation, theta(M). The ensuing intrinsic heterogeneity parameters, Gamma, for CdHA and CuHA complexes are in very good agreement with those obtained from dynamic electrochemical stripping chronopotentiometric measurements. The overall intraparticulate metal ion speciation is found to depend on theta...

Rare earth element recycling from waste nickel-metal hydride batteries

International Nuclear Information System (INIS)

Yang, Xiuli; Zhang, Junwei; Fang, Xihui

2014-01-01

Highlights: • Leaching kinetics of REEs has rarely been reported. • A new method, including hydrochloric acid leaching and oxalic acid precipitation, was proposed. • REEs recovery rate of 95.16% and pure rare earth oxides of 99% were obtained. • Leaching process was controlled by chemical reaction. • The kinetic equation was determined. - Abstract: With an increase in number of waste nickel-metal hydride batteries, and because of the importance of rare earth elements, the recycling of rare earth elements is becoming increasingly important. In this paper, we investigate the effects of temperature, hydrochloric acid concentration, and leaching time to optimize leaching conditions and determine leach kinetics. The results indicate that an increase in temperature, hydrochloric acid concentration, and leaching time enhance the leaching rate of rare earth elements. A maximum rare earth elements recovery of 95.16% was achieved at optimal leaching conditions of 70 °C, solid/liquid ratio of 1:10, 20% hydrochloric acid concentration, −74 μm particle size, and 100 min leaching time. The experimental data were best fitted by a chemical reaction-controlled model. The activation energy was 43.98 kJ/mol and the reaction order for hydrochloric acid concentration was 0.64. The kinetic equation for the leaching process was found to be: 1−(1−x) 1/3 =A/ρr 0 [HCl] 0.64 exp((−439,800)/(8.314T) )t. After leaching and filtration, by adding saturated oxalic solution to the filtrate, rare earth element oxalates were obtained. After removing impurities by adding ammonia, filtering, washing with dilute hydrochloric acid, and calcining at 810 °C, a final product of 99% pure rare earth oxides was obtained

Structural and magentic characterization of rare earth and transition metal films grown on epitaxial buffer films on semiconductor substrates

International Nuclear Information System (INIS)

Farrow, R.F.C.; Parkin, S.S.P.; Speriosu, V.S.; Bezinge, A.; Segmuller, A.P.

1989-01-01

Structural and magnetic data are presented and discussed for epitaxial films of rare earth metals (Dy, Ho, Er) on LaF 3 films on the GaAs(TTT) surface and Fe on Ag films on the GaAs(001) surface. Both systems exhibit unusual structural characteristics which influence the magnetic properties of the metal films. In the case of rare earth epitaxy on LaF 3 the authors present evidence for epitaxy across an incommensurate or discommensurate interface. Coherency strain is not transmitted into the metal which behaves much like bulk crystals of the rare earths. In the case of Fe films, tilted epitaxy and long-range coherency strain are confirmed by X- ray diffractometry. Methods of controlling some of these structural effects by modifying the epitaxial structures are presented

Modification of Non-Metallic Inclusions by Rare-Earth Elements in Microalloyed Steels

Directory of Open Access Journals (Sweden)

M. Opiela

2012-04-01

Full Text Available The modification of the chemical composition of non-metallic inclusions by rare-earth elements in the new-developed microalloyed steels was discussed in the paper. The investigated steels are assigned to production of forged elements by thermo- mechanical treatment. The steels were melted in a vaccum induction furnace and modification of non-metallic inclusions was carried out by the michmetal in the amount of 2.0 g per 1 kg of steel. It was found that using material charge of high purity and a realization of metallurgical process in vacuous conditions result in a low concentration of sulfur (0.004%, phosphorus (from 0.006 to 0.008% and oxygen (6 ppm. The high metallurgical purity is confirmed by a small fraction of non-metallic inclusions averaging 0.075%. A large majority of non-metallic inclusions are fine, globular oxide-sulfide or sulfide particles with a mean size 17m2. The chemical composition and morphology of non-metallic inclusions was modified by Ce, La and Nd, what results a small deformability of non- metallic inclusions during hot-working.

Crystal Fields in Dilute Rare-Earth Metals Obtained from Magnetization Measurements on Dilute Rare-Earth Alloys

DEFF Research Database (Denmark)

Touborg, P.; Høg, J.

1974-01-01

Crystal field parameters of Tb, Dy, and Er in Sc, Y, and Lu are summarized. These parameters are obtained from magnetization measurements on dilute single crystals, and successfully checked by a number of different methods. The crystal field parameters vary unpredictably with the rare-earth solute....... B40, B60, and B66 are similar in Y and Lu. Crystal field parameters for the pure metals Tb, Dy, and Er are estimated from the crystal fields in Y and Lu....

New technology of extracting the amount of rare earth metals from the red mud

International Nuclear Information System (INIS)

Martoyan, G A; Karamyan, G G; Vardan, G A

2016-01-01

The paper outlined the environmental and economic problems associated with red mud - the waste generated in processing of bauxite ore for aluminum production. The chemical analysis of red mud has identified a number of useful elements including rare earth metals. The electromembrane technology of red mud processing with extraction of valuable elements is described. A possible scheme of separation of these metals through electrolysis is also given. (paper)

Complexation-induced supramolecular assembly drives metal-ion extraction.

Science.gov (United States)

Ellis, Ross J; Meridiano, Yannick; Muller, Julie; Berthon, Laurence; Guilbaud, Philippe; Zorz, Nicole; Antonio, Mark R; Demars, Thomas; Zemb, Thomas

2014-09-26

Combining experiment with theory reveals the role of self-assembly and complexation in metal-ion transfer through the water-oil interface. The coordinating metal salt Eu(NO3)3 was extracted from water into oil by a lipophilic neutral amphiphile. Molecular dynamics simulations were coupled to experimental spectroscopic and X-ray scattering techniques to investigate how local coordination interactions between the metal ion and ligands in the organic phase combine with long-range interactions to produce spontaneous changes in the solvent microstructure. Extraction of the Eu(3+)-3(NO3(-)) ion pairs involves incorporation of the "hard" metal complex into the core of "soft" aggregates. This seeds the formation of reverse micelles that draw the water and "free" amphiphile into nanoscale hydrophilic domains. The reverse micelles interact through attractive van der Waals interactions and coalesce into rod-shaped polynuclear Eu(III) -containing aggregates with metal centers bridged by nitrate. These preorganized hydrophilic domains, containing high densities of O-donor ligands and anions, provide improved Eu(III) solvation environments that help drive interfacial transfer, as is reflected by the increasing Eu(III) partitioning ratios (oil/aqueous) despite the organic phase approaching saturation. For the first time, this multiscale approach links metal-ion coordination with nanoscale structure to reveal the free-energy balance that drives the phase transfer of neutral metal salts. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fabrication of Superhydrophobic and Luminescent Rare Earth/Polymer complex Films.

Science.gov (United States)

Wang, Zefeng; Ye, Weiwei; Luo, Xinran; Wang, Zhonggang

2016-04-18

The motivation of this work is to create luminescent rare earth/polymer films with outstanding water-resistance and superhydrophobicity. Specifically, the emulsion polymerization of styrene leads to core particles. Then core-shell-structured polymer nanoparticles are synthesized by copolymerization of styrene and acrylic acid on the core surface. The coordination reaction between carboxylic groups and rare earth ions (Eu(3+) and Tb(3+)) generates uniform spherical rare earth/polymer nanoparticles, which are subsequently complexed with PTFE microparticles to obtain micro-/nano-scaled PTFE/rare earth films with hierarchical rough morphology. The films exhibit large water contact angle up to 161° and sliding angle of about 6°, and can emit strong red and green fluorescence under UV excitation. More surprisingly, it is found that the films maintain high fluorescence intensity after submersed in water and even in aqueous salt solution for two days because of the excellent water repellent ability of surfaces.

Thermochemical properties of rare earth complexes with salicylic acid

International Nuclear Information System (INIS)

Yang Xuwu; Sun Wujuan; Ke Congyu; Zhang Hangguo; Wang Xiaoyan; Gao Shengli

2007-01-01

Fourteen rare earth complexes with salicylic acid RE(HSal) 3 .nH 2 O (HSal = C 7 H 5 O 3 ; RE = La-Sm, n = 2; RE = Eu-Lu, n = 1) were synthesized and characterized by elemental analysis, and their thermal decomposition mechanism were studied with TG-DTG technology. The constant-volume combustion energies of complexes, Δ c U, were determined by a precise rotating-bomb calorimeter at 298.15 K. Their standard molar enthalpies of combustion, Δ c H m 0 , and standard molar enthalpies of formation, Δ f H m o , were calculated

Crystallochemical analysis of rare-earth halogen-containing π-complexes

International Nuclear Information System (INIS)

Blatova, O.A.; Blatov, V.A.; Serezhkin, V.N.

2001-01-01

Dependence of the size of Ln atom action in coordination polyhedrons LnC n X m (X = F, Cl, Br) on its nature, coordination number, oxidation state and number of Ln-X bonds, was studied using 96 halogen-containing π-complexes of rare earth and yttrium (Ln) by way of example. A method of estimating ligand sizes in coordination sphere using the Voronoi-Dirichlet molecular polyhedrons was suggested. Influence of the ligands sizes on stability of π-complexes and presence of specific interactions in their structure was analyzed [ru

Modification of radiation sensitivity by salts of the metals beryllium and indium and the rare earths cerium, lanthanum and scandium

International Nuclear Information System (INIS)

Floersheim, G.L.

1995-01-01

The LD 50 of 46 salts of metals and rare earths (lanthanoids) was determined in mice. Half the LD 50 of the compounds was then combined with lethal radiation (10.5 Gy) and the modification of survival time was scored. Only the metals beryllium and indium and the rare earths cerium, lanthanum and scandium displayed activity in our assay. There were then tested at a wider range of lower doses and reduced survival time in a dose-dependent fashion. This appears to be compatible with enhancement of radiation sensitivity. The interaction of these metals and rare earths with radiation adds a new facet to their toxicological spectrum and, by enhancing radiation effects, may influence estimates of risk. On the other hand, radiosensitizing properties of the metals may be useful for further development of compounds to be used as adjuncts in specific situations of cancer radiotherapy. 31 refs., 1 fig., 1 tab

Accomplishing simple, solubility-based separations of rare earth elements with complexes bearing size-sensitive molecular apertures

OpenAIRE

Bogart, Justin A.; Cole, Bren E.; Boreen, Michael A.; Lippincott, Connor A.; Manor, Brian C.; Carroll, Patrick J.; Schelter, Eric J.

2016-01-01

Rare earth metals, La���Lu, Sc, and Y, are essential components of electronic materials and permanent magnets in diverse technologies. But, their mining and separations chemistry are unsustainable and plagued with supply problems. Recycling of consumer materials containing rare earths is a promising new source of these critical materials but similarly requires efficient separations. We report the use of a tripodal hydroxylaminato ligand, TriNOx3���, with rare earth cations that enable fast, e...

Synthesis and Spectral Characterization of Antifungal Sensitive Schiff Base Transition Metal Complexes

Science.gov (United States)

Sakthivel, A.; Rajasekaran, K.

2007-01-01

New N2O2 donor type Schiff base has been designed and synthesized by condensing acetoacetanilido-4-aminoantipyrine with 2-aminobenzoic acid in ethanol. Solid metal complexes of the Schiff base with Cu(II), Ni(II), Co(II), Mn(II), Zn(II), VO(IV), Hg(II) and Cd(II) metal ions were synthesized and characterized by elemental analyses, magnetic susceptibility, molar conduction, fast atom bombardment (FAB) mass, IR, UV-Vis, and 1H NMR spectral studies. The data show that the complexes have the composition of ML type. The UV-Vis. and magnetic susceptibility data of the complexes suggest a square-planar geometry around the central metal ion except VO(IV) complex which has square-pyramidal geometry. The in vitro antifungal activities of the compounds were tested against fungi such as Aspergillus niger, Aspergillus flavus, Rhizopus stolonifer, Candida albicans, Rhizoctonia bataicola and Trichoderma harizanum. All the metal complexes showed stronger antifungal activities than the free ligand. The minimum inhibitory concentrations (MIC) of the metal complexes were found in the range of 10~31 µg/ml. PMID:24015086

Distributions of alkali metals, alkaline earth metals and halogens in cabbage leaves

International Nuclear Information System (INIS)

Tsukada, Hirofumi; Takeda, Akira; Hasegawa, Hidenao

2007-01-01

The distributions of stable elements in plant components provide useful information for understanding the behavior of radionuclides in plants. An entire cabbage plant sample was collected from an experimental field, and the distributions of alkali metals (K, Rb and Cs), alkaline earth metals (Ca, Sr and Ba) and halogens (Cl and I) were determined for cabbage leaves at different positions. The concentration of Cs in outer (older) cabbage leaves was higher than that in inner (younger) leaves, but the distributions of K and Rb concentrations were relatively similar in cabbage leaves, independent of leaf positions. The concentration of Sr in older cabbage leaves was one order of magnitude higher than that in younger leaves. The distributions of Ca, Ba and Sr concentrations in the plant followed a similar pattern. The concentrations of halogens were also very rich in the outer leaves. The percentage distributions of Cs, Sr, Cl and I in the inedible (extreme outer) leaves were 77, 91, 93 and 96% of the total content in the leaf part, respectively. These results show that the inedible plant components are important for understanding the transfer of the radioactive Cs, Sr Cl and I in soil-plant systems. (author)

Anticancer Activity of Metal Complexes: Involvement of Redox Processes

Science.gov (United States)

Jungwirth, Ute; Kowol, Christian R.; Keppler, Bernhard K.; Hartinger, Christian G.; Berger, Walter; Heffeter, Petra

2012-01-01

Cells require tight regulation of the intracellular redox balance and consequently of reactive oxygen species for proper redox signaling and maintenance of metal (e.g., of iron and copper) homeostasis. In several diseases, including cancer, this balance is disturbed. Therefore, anticancer drugs targeting the redox systems, for example, glutathione and thioredoxin, have entered focus of interest. Anticancer metal complexes (platinum, gold, arsenic, ruthenium, rhodium, copper, vanadium, cobalt, manganese, gadolinium, and molybdenum) have been shown to strongly interact with or even disturb cellular redox homeostasis. In this context, especially the hypothesis of “activation by reduction” as well as the “hard and soft acids and bases” theory with respect to coordination of metal ions to cellular ligands represent important concepts to understand the molecular modes of action of anticancer metal drugs. The aim of this review is to highlight specific interactions of metal-based anticancer drugs with the cellular redox homeostasis and to explain this behavior by considering chemical properties of the respective anticancer metal complexes currently either in (pre)clinical development or in daily clinical routine in oncology. PMID:21275772

Selenophene transition metal complexes

Energy Technology Data Exchange (ETDEWEB)

White, Carter James [Iowa State Univ., Ames, IA (United States)

1994-07-27

This research shows that selenophene transition metal complexes have a chemistry that is similar to their thiophene analogs. Selenophene coordination has been demonstrated and confirmed by molecular structure in both the η⁵- and the η¹(Se)-coordination modes. The reaction chemistry of selenophene complexes closely resembles that of the analogous thiophene complexes. One major difference, however, is that selenophene is a better donor ligand than thiophene making the selenophene complexes more stable than the corresponding thiophene complexes. The ⁷⁷Se NMR chemical shift values for selenophene complexes fall within distinct regions primarily depending on the coordination mode of the selenophene ligand. In the final paper, the C-H bond activation of η¹(S)-bound thiophenes, η¹(S)-benzothiophene and η¹(Se)-bound selenophenes has been demonstrated. The deprotonation and rearrangement of the η¹(E)-bound ligand to the carbon bound L-yl complex readily occurs in the presence of base. Reprotonation with a strong acid gives a carbene complex that is unreactive towards nucleophilic attack at the carbene carbon and is stable towards exposure to air. The molecular structure of [Cp(NO)(PPh₃)Re(2-benzothioenylcarbene)]O₃SCF₃ was determined and contains a Re-C bond with substantial double bond character. Methyl substitution for the thienylcarbene or selenylcarbene gives a carbene that rearranges thermally to give back the η¹(E)-bound complex. Based on these model reactions, a new mechanism for the H/D exchange of thiophene over the hydrodesulfurization catalyst has been proposed.

Dispersion coefficients for H and He interactions with alkali-metal and alkaline-earth-metal atoms

International Nuclear Information System (INIS)

Mitroy, J.; Bromley, M.W.J.

2003-01-01

The van der Waals coefficients C 6 , C 8 , and C 10 for H and He interactions with the alkali-metal (Li, Na, K, and Rb) and alkaline-earth-metal (Be, Mg, Ca, and Sr) atoms are determined from oscillator strength sum rules. The oscillator strengths were computed using a combination of ab initio and semiempirical methods. The dispersion parameters generally agree with close to exact variational calculations for Li-H and Li-He at the 0.1% level of accuracy. For larger systems, there is agreement with relativistic many-body perturbation theory estimates of C 6 at the 1% level. These validations for selected systems attest to the reliability of the present dispersion parameters. About half the present parameters lie within the recommended bounds of the Standard and Certain compilation [J. Chem. Phys. 83, 3002 (1985)

Anharmonic Vibrational Spectroscopy on Metal Transition Complexes

Science.gov (United States)

Latouche, Camille; Bloino, Julien; Barone, Vincenzo

2014-06-01

Advances in hardware performance and the availability of efficient and reliable computational models have made possible the application of computational spectroscopy to ever larger molecular systems. The systematic interpretation of experimental data and the full characterization of complex molecules can then be facilitated. Focusing on vibrational spectroscopy, several approaches have been proposed to simulate spectra beyond the double harmonic approximation, so that more details become available. However, a routine use of such tools requires the preliminary definition of a valid protocol with the most appropriate combination of electronic structure and nuclear calculation models. Several benchmark of anharmonic calculations frequency have been realized on organic molecules. Nevertheless, benchmarks of organometallics or inorganic metal complexes at this level are strongly lacking despite the interest of these systems due to their strong emission and vibrational properties. Herein we report the benchmark study realized with anharmonic calculations on simple metal complexes, along with some pilot applications on systems of direct technological or biological interest.

Cation exchange separation of 16 rare earth metals by microscale high-performance liquid chromatography

International Nuclear Information System (INIS)

Ishii, D.; Hirose, A.; Iwasaki, Y.

1978-01-01

The separation of rare earth metals has been studied with a microcolumn of 0.5 mm i.d. and 75 mm length, packed with TSK LS-212 high-performance cation exchange resin. A micro-feeder (Model MF-2, from Azumadenki Kogyo) was used to drive carrier and sample solutions through the ion exchange column and detection cell. By combining a 250 μl syringe and a 0.5 mm i.d. sampling tube the micro-feeder, 0.1-1.0 μl rare earth metals were separated within 38 min, using only 304 μl of 0.4M α-hydroxy-isobutyric acid solution adjusted to pH 3.1-6.0 with ammonia solution as gradient carrier solution. The gradient elution was successfully performed by applying a new technique developed for microscale liquid chromatography. (author)

[Ultraviolet-visible spectrometry analysis of insoluble xanthate heavy metal complexes].

Science.gov (United States)

Qiu, Bo; Liu, Jin-Feng; Liu, Yao-Chi; Yang, Zhao-Guang; Li, Hai-Pu

2014-11-01

A ultraviolet-visible spectrometry method of determining insoluble xanthate heavy metal complexes in flotation wastewater was the first time to be put forward. In this work, the changes of ultraviolet-visible spectra of xanthate solution after the addition of various heavy metal ions were investigated firstly. It was found that Pb2+ and Cu2+ can form insoluble complexes with xanthate, while Fe2+, Zn2+ and Mn2+ have little effect on the ultraviolet absorption of xanthate solution. Then the removal efficiencies of filter membrane with different pore sizes were compared, and the 0.22 μm membrane was found to be effective to separate copper xanthate or lead xanthate from the filtrate. Furthermore, the results of the study on the reaction of sodium sulfide and insoluble xanthate heavy metal complexes showed that S(2-) can release the xanthate ion quantitatively from insoluble complexes to solution. Based on the above research, it was concluded that the amount of insoluble xanthate heavy metal complexes in water samples can be obtained through the increase of free xanthate in the filtrate after the addition of sodium sulfide. Finally, the feasibility of this method was verified by the application to the analysis of flotation wastewater from three ore-dressing plants in the Thirty-six Coves in Chenzhou.

New Transition metal assisted complex borohydrides for hydrogen storage

International Nuclear Information System (INIS)

Sesha Srinivasan; Elias Lee Stefanakos; Yogi Goswami

2006-01-01

High capacity hydrogen storage systems are indeed essential for the on-board vehicular application that leads to the pollution free environment. Apart from the various hydrogen storage systems explored in the past, complex hydrides involving light weight alkali/alkaline metals exhibits promising hydrogenation/ dehydrogenation characteristics. New transition metal assisted complex borohydrides [Zn(BH 4 ) 2 ] have been successfully synthesized by an inexpensive mechano-chemical process. These complex hydrides possesses gravimetric hydrogen storage capacity of ∼8.4 wt.% at around 120 C. We have determined the volumetric hydrogen absorption and desorption of these materials for a number of cycles. Another complex borohydride mixture LiBH 4 /MgH 2 catalyzed with ZnCl 2 has been synthesized and characterized using various analytical techniques. (authors)

μSR-studies of magnetic properties of metallic rare earth compounds

International Nuclear Information System (INIS)

Asch, L.; Kalvius, G.M.; Chappert, J.; Yaouanc, A.; Hartmann, O.; Karlsson, E.; Wappling, R.

1984-01-01

Positive muons can probe the magnitude and the time dependence of the magnetic field at interstitial sites in condensed matter. Thus the relatively new techniques of muons spin rotation and muon spin relaxation have become unique tools for studying magnetism. After a brief introduction into the experimental method we then discuss measurements on the elemental rare earth metals and on intermetallic compounds, in particular on the cubic Laves phases REAl 2

Characterization of Anthraquinone-DerivedRedox Switchable Ionophores and Their Complexes with Li+, Na+, K+, Ca+, and Mg+ Metal Ions

Directory of Open Access Journals (Sweden)

Vaishali Vyas

2011-01-01

Full Text Available Anthraquinone derived redox switchable ionophores 1,5 bis (2-(2-(2-ethoxy ethoxy ethoxyanthracene-9,10-dione (V1 and 1,8-bis(2-(2-(2-ethoxyethoxyethoxy anthracene—9,10-dione (V2 have been used for isolation, extraction and liquid membrane transport studies of Li+, Na+, K+, Ca2+ and Mg2+ metal ions. These isolated complexes were characterized by melting point determination, CV and IR, 1H NMR spectral analysis. Ionophore V2 shows maximum shift in reduction potential (ΔE with Ca(Pic2. The observed sequence for the shifting in reduction potential (ΔE between V2 and their complexes is V2 calcium picrate (42 mV > V2 potassium picrate (33 mV > V2 lithium picrate (25 mV > V2 sodium picrate (18 mV > V2 magnesium picrate (15 mV. These findings are also supported by results of extraction, back extraction and transport studies. Ionophore V2 complexed with KPic and showed much higher extractability and selectivity towards K+ than V1. These synthetic ionophores show positive and negative cooperativity towards alkali and alkaline earth metal ions in reduced and oxidized state. Hence, this property can be used in selective separation and enrichment of metal ions using electrochemically driven ion transport.

Self-Assembly of Discrete Metal Complexes in Aqueous Solution via Block Copolypeptide Amphiphiles

Directory of Open Access Journals (Sweden)

Timothy J. Deming

2013-01-01

Full Text Available The integration of discrete metal complexes has been attracting significant interest due to the potential of these materials for soft metal-metal interactions and supramolecular assembly. Additionally, block copolypeptide amphiphiles have been investigated concerning their capacity for self-assembly into structures such as nanoparticles, nanosheets and nanofibers. In this study, we combined these two concepts by investigating the self-assembly of discrete metal complexes in aqueous solution using block copolypeptides. Normally, discrete metal complexes such as [Au(CN2]−, when molecularly dispersed in water, cannot interact with one another. Our results demonstrated, however, that the addition of block copolypeptide amphiphiles such as K183L19 to [Au(CN2]− solutions induced one-dimensional integration of the discrete metal complex, resulting in photoluminescence originating from multinuclear complexes with metal-metal interactions. Transmission electron microscopy (TEM showed a fibrous nanostructure with lengths and widths of approximately 100 and 20 nm, respectively, which grew to form advanced nanoarchitectures, including those resembling the weave patterns of Waraji (traditional Japanese straw sandals. This concept of combining block copolypeptide amphiphiles with discrete coordination compounds allows the design of flexible and functional supramolecular coordination systems in water.

Detection of nanocrystallinity by X-ray absorption spectroscopy in thin film transition metal/rare-earth atom, elemental and complex oxides

International Nuclear Information System (INIS)

Edge, L.F.; Schlom, D.G.; Stemmer, S.; Lucovsky, G.; Luning, J.

2006-01-01

Nanocrystallinity has been detected in the X-ray absorption spectra of transition metal and rare-earth oxides by (i) removal of d-state degeneracies in the (a) Ti and Sc L 3 spectra of TiO 2 and LaScO 3 , respectively, and (b) O K 1 spectra of Zr(Hf)O 2 , Y 2 O 3 , LaScO 3 and LaAlO 3 , and by the (ii) detection of the O-atom vacancy in the O K 1 edge ZrO 2 -Y 2 O 3 alloys. Spectroscopic detection is more sensitive than X-ray diffraction with a limit of ∼2 nm as compared to >5 mm. Other example includes detection of ZrO 2 nanocrystallinity in phase-separated Zr(Hf) silicate alloys

Synthesis of amino acid rare earth complexes and its application in agriculture

International Nuclear Information System (INIS)

Luo, G.-T.; Lian, P.; Hu, Y.H.; Guo, G.-R.

1998-01-01

Full text: The application of rare-earth compounds in agriculture has been widely reported. So far, most rare-earth compounds used in agriculture were inorganic salt and they were difficult to be absorbed by croup. The synthesis method and structure of amino acid rare-earth complexes have been reported. In this paper, we reported the preparation of mixed amino acids rare-earth complexes and their application in agriculture. The mixed amino acids were obtained by hydrolysis of waste natural protein. Rare earth was lanthanum oxide(99%). Mixed amino acids lanthanum complexes(MALa) was prepared according to the previous method. Investigation to the effect of croup by MALa, we have make tests of citrus, rice and mung bean. The results show as follows: 1) When the experiment group citrus was sprinkled twice 400ppm MALa at bouquet stage and young fruit stage, the sugar, morose, sucrose, soluble solid matter and vitamin C of fruit were increased 21%, 20%, 22%, 22% and 6% as compared to the control group, respectively. The area of leaf and foliage branch in Spring were also increased 4.6% and 2.2%. 2) When the rice was sprinkled 300ppm MALa at early tillering stage, the productively of rice was addition to 10-15%, and the relative effect of prevention was 45.61% for sheath and culm blight of rice. 3) In the test of mungbean growth, the low consistency of MALa ( 250ppm) retain from sprouting seed. As the same time, it was similar action to seeding growth. Preliminary results indicated MLAa could used as the plant growth regulation agent on the croup. Investigation to the effect of MALa on other croup and the mechanism of biological effect on the croup are still going on

On effect of surfactants on formation of metal trihydroxyfluoronates

International Nuclear Information System (INIS)

Antonovich, V.P.; Novoselova, M.M.; Nazarenko, V.A.

1984-01-01

Literary data on the practical application and properties of metal complexes with different trihydroxyfluorone derivatives being formed in the presence of surfactants, on the effect of detergents on acidic-Uasic cOaracteristics of reagents, on the mechanism of formation of coloured metal complexes with 2,3,7- and 3,4,5-trihydroxyfluorons, are systematized. Characteristics (formation conditions, properties) of complexes of Mo(6), Zr(4), Nb(5), W(6), V(4), Te(4), U(6), rare earths, Ta(5), Se(3), Hf(4), In(3) and other metals, are considered. Special attention is paid to the analysis of different approaches to the mechanism of surfactant effect on metal reaction with chromophore organic analytic reagents

Synthesis, spectral studies and biological evaluation of 2-aminonicotinic acid metal complexes

Science.gov (United States)

Nawaz, Muhammad; Abbasi, Muhammad Waseem; Hisaindee, Soleiman; Zaki, Muhammad Javed; Abbas, Hira Fatima; Mengting, Hu; Ahmed, M. Arif

2016-05-01

We synthesized 2-aminonicotinic acid (2-ANA) complexes with metals such as Co(II), Fe(III), Ni(II), Mn(II), Zn(II), Ag(I),Cr(III), Cd(II) and Cu(II) in aqueous media. The complexes were characterized and elucidated using FT-IR, UV-Vis, a fluorescence spectrophotometer and thermo gravimetric analysis (TGA). TGA data showed that the stoichiometry of complexes was 1:2 metal/ligand except for Ag(I) and Mn(II) where the ratio was 1:1. The metal complexes showed varied antibacterial, fungicidal and nematicidal activities. The silver and zinc complexes showed highest activity against Bacillus subtilis and Bacillus licheniformis respectively. Fusarium oxysporum was highly susceptible to nickel and copper complexes whereas Macrophomina phaseolina was completely inert to the complexes. The silver and cadmium complexes were effective against the root-knot nematode Meloidogyne javanica.

Handbook on the physics and chemistry of rare earths

International Nuclear Information System (INIS)

Gschneidner, K.A. Jr.; Eyring, L.

1982-01-01

This handbook is a six-volume work which covers the entire rare earth field in an integrated manner. Each chapter is a comprehensive, up-to-date, critical review of a particular segment of the field. The first volume is devoted to the rare earth metals, the second to rare earth alloys and intermetallics, and the third and fourth volumes to the non-metallic rare earth materials, including solutions, complexes and bioinorganic substances, in addition to solid inorganic compounds. The electronic structure of these unique elements is the primary basis of understanding their physical, metallurgical and chemical natures. The interrelationship of the 4f and valence electrons and the observed optical, electrical, magnetic, crystallographic, elastic, thermal, mechanical, chemical, geochemical and biological behaviors is brought forth time and again throughout the chapters. Also discussed are the preparative, separation and solution chemistry of the elements and their compounds and the various chemical and physical analytical methods for determining the rare earths in various materials and impurities in a rare earth matrix. Vol. 5 is a update complement of the previous volumes. Volume 6 is concerned with ternary and higher order materials. (Auth.)

Features of proteolytic properties of tetraphenylporphyrin complex with lanthanide group metals

Science.gov (United States)

Tobolkina, Elena A.; Skripnikova, Tatiana A.; Starikova, Anna A.; Shumilova, Galina I.; Pendin, Andrey A.

2018-01-01

Demetallation of metalloporphyrin molecules is one of the essential degradation reactions in photosynthesis. The effect of metalloporphyrin nature on removal of central metals from tetraphenylporphyrin complexes based on lanthanide group metals (Dy, Er, Lu, Ho) has been studied. pH values, at which the metal ions leave the metalloporphyrin complex were established using two-phase spectrophotometric titration with potentiometric pH-control. The pH values decrease with the increase of atomic numbers of lanthanide groups, as well as with increase of 4f-electrons. The reaction of an extra ligand exchange for the hydroxide ion was studied. For Dy-, Er- and Ho-tetraphenylporphyrin complexes one particle of extra ligand coordinates with one porphyrin complex. A complex with dimeric particles can be formed for the system of Lu-tetraphenylporphyrin. Constants of the ion exchange reactions were calculated.

Late transition metal m-or chemistry and D6 metal complex photoeliminations

Energy Technology Data Exchange (ETDEWEB)

Sharp, Paul [Univ. of Missouri, Columbia, MO (United States)

2015-07-31

With the goal of understanding and controlling photoreductive elimination reactions from d6 transition metal complexes as part of a solar energy storage cycle we have investigated the photochemistry of Pt(IV) bromo, chloro, hydroxo, and hydroperoxo complexes. Photoreductive elimination reactions occur for all of these complexes and appear to involve initial Pt-Br, Pt-Cl, or Pt-O bond fission. In the case of Pt-OH bond fission, the subsequent chemistry can be controlled through hydrogen bonding to the hydroxo group.

Electrochemical behaviour of β-diketones and their complexes with metals

International Nuclear Information System (INIS)

Kamenev, A.I.; Dzherippa, L.G.; Efimov, I.P.

1985-01-01

Literature on the problems of polarography of β-dicetones and β-dicetonates of metals including rare earths covering the period from sixties up today is reviewed. Conditions, mechanism and practical possibilities of the process are considered. A possibility of using polarography for studying fantomerism in the series of cyclic β-dicetones is noted

Formation of an integrated holding company to produce rare-earth metal articles

Science.gov (United States)

Bogdanov, S. V.; Grishaev, S. I.

2013-12-01

The possibility of formation of a Russian holding company for the production of rare-earth metal articles under conditions of its increasing demand on the world market is considered. It is reasonable to ensure stable business operation on the market under conditions of state-private partnership after the fraction of soled products is determined and supported by the competitive advantages of Russian products.

Structure and catalytic properties of metal β-diketonate complexes with oxygen-containing compounds

International Nuclear Information System (INIS)

Nizel'skij, Yu.N.; Ishchenko, S.S.; Lipatova, T.Eh.

1985-01-01

The results of researches published in recent 15-20 years of complexes of metal β-diketonates (including Cr 3+ , VO 2+ , MoOΛ2 2+ , Co 3+ , Mn 3+ , Ni 2+ , Fe 3+ ) with oxygen-containing compounds (alcohols, glycols, phenols, hydroperoxides, aldehydes, esters, etc.) playing an important role in catalytic processes of oxidation, addition, polymerization and copolymerization are reviewed. Data on the nature of chemical bond of oxygen-containing reacting agents with metal β-diketonates, on structure of metal β-diketonate complexes with oxygen-containing reacting agents and thermodynamics of complexing as well as on activation of reacting agents in complexes and catalytic properties of metal β-diketonates are discussed. Stored materials make it possible to exercise directed control of metal β-diketonate activity

Synthesis of complex plutonium oxides with alkaline-earth metals

International Nuclear Information System (INIS)

Suzuki, Yasufumi; Nakajima, Kunihisa; Iwai, Takashi; Ohmichi, Toshihiko; Yamawaki, Michio.

1995-03-01

Complex plutonium(IV) oxides with strontium and barium, SuPuO 3 and BaPuO 3 , were synthesized and their crystal structure was analyzed. Compacted mixture of plutonium dioxide powder and the carbonate of strontium or barium was heated in a stream of argon gas using a cell with a small orifice. The products obtained were found to be composed of a nearly single phase showing the structure of orthorhombic slightly distorted from cubic. (author)

Metal-silicate Partitioning and Its Role in Core Formation and Composition on Super-Earths

Energy Technology Data Exchange (ETDEWEB)

Schaefer, Laura; Petaev, M. I.; Sasselov, Dimitar D. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Jacobsen, Stein B.; Remo, John L., E-mail: lschaefer@asu.edu [Harvard University, Department of Earth and Planetary Sciences, 20 Oxford St., Cambridge, MA 02138 (United States)

2017-02-01

We use a thermodynamic framework for silicate-metal partitioning to determine the possible compositions of metallic cores on super-Earths. We compare results using literature values of the partition coefficients of Si and Ni, as well as new partition coefficients calculated using results from laser shock-induced melting of powdered metal-dunite targets at pressures up to 276 GPa, which approaches those found within the deep mantles of super-Earths. We find that larger planets may have little to no light elements in their cores because the Si partition coefficient decreases at high pressures. The planet mass at which this occurs will depend on the metal-silicate equilibration depth. We also extrapolate the equations of state (EOS) of FeO and FeSi alloys to high pressures, and present mass–radius diagrams using self-consistent planet compositions assuming equilibrated mantles and cores. We confirm the results of previous studies that the distribution of elements between mantle and core will not be detectable from mass and radius measurements alone. While observations may be insensitive to interior structure, further modeling is sensitive to compositionally dependent properties, such as mantle viscosity and core freeze-out properties. We therefore emphasize the need for additional high pressure measurements of partitioning as well as EOSs, and highlight the utility of the Sandia Z-facilities for this type of work.

No Giant Two-Ion Anisotropy in the Heavy-Rare-Earth Metals

DEFF Research Database (Denmark)

Lindgård, Per-Anker

1976-01-01

A new Bose-operator expansion of tensor operators is applied to the heavy-rare-earth metals. The Er data for the cone phase have been analyzed successfully with single-ion anisotropy and isotropic exchange interaction. The Tb data can be understood on the same basis. The previously found large two......-ion anisotropy was due to an inadequate treatment of the large single-ion anisotropy leading to an incorrect expression for the spin-wave energy....

Teleconnections in complex human-Earth system models

Science.gov (United States)

Calvin, K. V.; Edmonds, J.

2017-12-01

Human systems and physical Earth systems are closely coupled and interact in complex ways that are sometimes surprising. This presentation discusses a few examples of system interactions. We consider the coupled energy-water-land-economy systems. We show how reductions in fossil fuel emissions are inversely coupled to land rents, food prices and deforestation. We discuss how water shortages in one part of the world is propagated to other distant parts of the world. We discuss the sensitivity of international trade patterns to energy and land systems technology and markets, and the potentially unanticipated results that can emerge.

Tunable electronic and magnetic properties in germanene by alkali, alkaline-earth, group III and 3d transition metal atom adsorption.

Science.gov (United States)

Li, Sheng-shi; Zhang, Chang-wen; Ji, Wei-xiao; Li, Feng; Wang, Pei-ji; Hu, Shu-jun; Yan, Shi-shen; Liu, Yu-shen

2014-08-14

We performed first-principles calculations to study the adsorption characteristics of alkali, alkali-earth, group III, and 3d transition-metal (TM) adatoms on germanene. We find that the adsorption of alkali or alkali-earth adatoms on germanene has minimal effects on geometry of germanene. The significant charge transfer from alkali adatoms to germanene leads to metallization of germanene, whereas alkali-earth adatom adsorption, whose interaction is a mixture of ionic and covalent, results in semiconducting behavior with an energy gap of 17-29 meV. For group III adatoms, they also bind germanene with mixed covalent and ionic bonding character. Adsorption characteristics of the transition metals (TMs) are rather complicated, though all TM adsorptions on germanene exhibit strong covalent bonding with germanene. The main contributions to the strong bonding are from the hybridization between the TM 3d and Ge pz orbitals. Depending on the induced-TM type, the adsorbed systems can exhibit metallic, half-metallic, or semiconducting behavior. Also, the variation trends of the dipole moment and work function with the adsorption energy across the different adatoms are discussed. These findings may provide a potential avenue to design new germanene-based devices in nanoelectronics.

Synthesis, spectral studies and biological evaluation of 2-aminonicotinic acid metal complexes.

Science.gov (United States)

Nawaz, Muhammad; Abbasi, Muhammad Waseem; Hisaindee, Soleiman; Zaki, Muhammad Javed; Abbas, Hira Fatima; Mengting, Hu; Ahmed, M Arif

2016-05-15

We synthesized 2-aminonicotinic acid (2-ANA) complexes with metals such as Co(II), Fe(III), Ni(II), Mn(II), Zn(II), Ag(I),Cr(III), Cd(II) and Cu(II) in aqueous media. The complexes were characterized and elucidated using FT-IR, UV-Vis, a fluorescence spectrophotometer and thermo gravimetric analysis (TGA). TGA data showed that the stoichiometry of complexes was 1:2 metal/ligand except for Ag(I) and Mn(II) where the ratio was 1:1. The metal complexes showed varied antibacterial, fungicidal and nematicidal activities. The silver and zinc complexes showed highest activity against Bacillus subtilis and Bacillus licheniformis respectively. Fusarium oxysporum was highly susceptible to nickel and copper complexes whereas Macrophomina phaseolina was completely inert to the complexes. The silver and cadmium complexes were effective against the root-knot nematode Meloidogyne javanica. Copyright © 2016 Elsevier B.V. All rights reserved.

Metal oxalate complexes as novel inorganic dopants: Studies on ...

Indian Academy of Sciences (India)

Unknown

UV-visible and IR spectral features not only confirmed the polyaniline doping by complex anions but also substantiated ... MoS3 dopant. Although inorganic metal complexes bear- ... distilled water and then with methanol and acetone until.

Synthesis, characterization, anti-microbial, DNA binding and cleavage studies of Schiff base metal complexes

Directory of Open Access Journals (Sweden)

Poomalai Jayaseelan

2016-09-01

Full Text Available A novel Schiff base ligand has been prepared by the condensation between butanedione monoxime with 3,3′-diaminobenzidine. The ligand and metal complexes have been characterized by elemental analysis, UV, IR, 1H NMR, conductivity measurements, EPR and magnetic studies. The molar conductance studies of Cu(II, Ni(II, Co(II and Mn(II complexes showed non-electrolyte in nature. The ligand acts as dibasic with two N4-tetradentate sites and can coordinate with two metal ions to form binuclear complexes. The spectroscopic data of metal complexes indicated that the metal ions are complexed with azomethine nitrogen and oxyimino nitrogen atoms. The binuclear metal complexes exhibit octahedral arrangements. DNA binding properties of copper(II metal complex have been investigated by electronic absorption spectroscopy. Results suggest that the copper(II complex bind to DNA via an intercalation binding mode. The nucleolytic cleavage activities of the ligand and their complexes were assayed on CT-DNA using gel electrophoresis in the presence and absence of H2O2. The ligand showed increased nuclease activity when administered as copper complex and copper(II complex behave as efficient chemical nucleases with hydrogen peroxide activation. The anti-microbial activities and thermal studies have also been studied. In anti-microbial activity all complexes showed good anti-microbial activity higher than ligand against gram positive, gram negative bacteria and fungi.

Molecular Speciation of Trace Metal Organic Complexes in the Pacific Ocean

Science.gov (United States)

Repeta, D.; Boiteau, R. M.; Bundy, R. M.; Babcock-Adams, L.

2017-12-01

Microbial production across approximately one third of the surface ocean is limited by extraordinarily low (picomolar) concentrations of dissolved iron, essentially all of which is complexed to strong organic ligands of unknown composition. Other biologically important trace metals (cobalt, copper, zinc, nickel) are also complexed to strong organic ligands, which again have not been extensively characterized. Nevertheless, organic ligands exert a strong influence on metal bioavailability and toxicity. For example, amendment experiments using commercially available siderophores, organic compounds synthesized by microbes to facilitate iron uptake, show these ligands can both facilitate or impede iron uptake depending on the siderophore composition and available uptake pathways. Over the past few years we have developed analytical techniques using high pressure liquid chromatography interfaced with inductively coupled plasma and electrospray ionization mass spectrometry to identify and quantify trace metal organic complexes in laboratory cultures of marine microbes and in seawater. We found siderophores to be widely distributed in the ocean, particularly in regions characterized by low iron concentrations. We also find chemically distinct complexes of copper, zinc, colbalt and nickel that we have yet to fully characterize. We will discuss some of our recent work on trace metal organic speciation in seawater and laboratory cultures, and outline future efforts to better understand the microbial cycling of trace metal organic complexes in the sea.

Raman spectroscopy of DNA-metal complexes. II. The thermal denaturation of DNA in the presence of Sr2+, Ba2+, Mg2+, Ca2+, Mn2+, Co2+, Ni2+, and Cd2+.

Science.gov (United States)

Duguid, J G; Bloomfield, V A; Benevides, J M; Thomas, G J

1995-12-01

Differential scanning calorimetry, laser Raman spectroscopy, optical densitometry, and pH potentiometry have been used to investigate DNA melting profiles in the presence of the chloride salts of Ba2+, Sr2+, Mg2+, Ca2+, Mn2+, Co2+, Ni2+, and Cd2+. Metal-DNA interactions have been observed for the molar ratio [M2+]/[PO2-] = 0.6 in aqueous solutions containing 5% by weight of 160 bp mononucleosomal calf thymus DNA. All of the alkaline earth metals, plus Mn2+, elevate the melting temperature of DNA (Tm > 75.5 degrees C), whereas the transition metals Co2+, Ni2+, and Cd2+ lower Tm. Calorimetric (delta Hcal) and van't Hoff (delta HVH) enthalpies of melting range from 6.2-8.7 kcal/mol bp and 75.6-188.6 kcal/mol cooperative unit, respectively, and entropies from 17.5 to 24.7 cal/K mol bp. The average number of base pairs in a cooperative melting unit () varied from 11.3 to 28.1. No dichotomy was observed between alkaline earth and transition DNA-metal complexes for any of the thermodynamic parameters other than their effects on Tm. These results complement Raman difference spectra, which reveal decreases in backbone order, base unstacking, distortion of glycosyl torsion angles, and rupture of hydrogen bonds, which occur after thermal denaturation. Raman difference spectroscopy shows that transition metals interact with the N7 atom of guanine in duplex DNA. A broader range of interaction sites with single-stranded DNA includes ionic phosphates, the N1 and N7 atoms of purines, and the N3 atom of pyrimidines. For alkaline earth metals, very little interaction was observed with duplex DNA, whereas spectra of single-stranded complexes are very similar to those of melted DNA without metal. However, difference spectra reveal some metal-specific perturbations at 1092 cm-1 (nPO2-), 1258 cm-1 (dC, dA), and 1668 cm-1 (nC==O, dNH2 dT, dG, dC). Increased spectral intensity could also be observed near 1335 cm-1 (dA, dG) for CaDNA. Optical densitometry, employed to detect DNA

Photochemical activation and reactivity of polynuclear transition metal complex molecules. Final report

International Nuclear Information System (INIS)

Endicott, J.F.; Lintvedt, R.L.

1982-06-01

Several bi- and trinuclear metal complexes containing ligands from β-polyketonates have been synthesized and characterized including homo- and hetero-polynuclear complexes. New synthetic approaches to the preparation of heterobi- and trinuclear complexes have been developed that allow the preparation of a large number of molecules containing heavy-metal ions such as Pd 2+ or UO 2 2+ and a first-row transition-metal ion. The electrochemical properties of these complexes have been investigated and many exhibit the ability to transfer two electrons at very nearly the same potential. Photochemical studies on binuclear Cu(II) and Ni(II) showed that these compounds yielded reduced metal species and decomposition upon irradiation. Luminescence of hetero-complexes of uranyl polyketonates is observed at 77 0 K with the UO 2 2+ moiety functioning as an isolated chromophore in which emission is observed only on direct excitation of UO 2 2+ and energy transfer to lower states in the molecule is not observed

Inkjet Printing of 3D Metallic Silver Complex Microstructures

NARCIS (Netherlands)

Wits, Wessel Willems; Sridhar, Ashok; Dimitrov, D.

2010-01-01

To broaden the scope of inkjet printing, this paper focuses on printing of an organic silver complex ink on glass substrates towards the fabrication of metallic 3D microstructures. The droplet formation sequence of the inkjet printer is optimised to print continuous layers of metal. A brief

The impact of metal transport processes on bioavailability of free and complex metal ions in methanogenic granular sludge

NARCIS (Netherlands)

Bartacek, J.; Fermoso, F.G.; Vergeldt, F.; Gerkema, E.; Maca, J.; As, van H.; Lens, P.N.L.

2012-01-01

Bioavailability of metals in anaerobic granular sludge has been extensively studied, because it can have a major effect on metal limitation and metal toxicity to microorganisms present in the sludge. Bioavailability of metals can be manipulated by bonding to complexing molecules such as

Extraction of rare earth metals (3) from aqueous solutions containing thorium and uranyl nitrates

International Nuclear Information System (INIS)

Pyartman, A.K.; Kopyrin, A.A.; Berinskij, A.E.; Keskinov, V.A.

2000-01-01

Isotherms of extraction of rare earth metals (3) from aqueous solutions containing thorium and uranyl nitrates by solutions of tributylphosphate (TBP) and diisooctylmethylphosphonate (DIOMP) in kerosene at 298.15 Deg C and pH 1 are presented. Equations for description of interphase distribution of components of the systems considered are suggested. These equations describe distribution of components adequately in the systems of thorium nitrate (uranyl nitrate) - rare earth nitrates - (TBP, DIOMP) in the case of wide variation of phase compositions. Dependences of separation factors on composition of aqueous phase are considered [ru

Rare earth element and rare metal inventory of central Asia

Science.gov (United States)

Mihalasky, Mark J.; Tucker, Robert D.; Renaud, Karine; Verstraeten, Ingrid M.

2018-03-06

Rare earth elements (REE), with their unique physical and chemical properties, are an essential part of modern living. REE have enabled development and manufacture of high-performance materials, processes, and electronic technologies commonly used today in computing and communications, clean energy and transportation, medical treatment and health care, glass and ceramics, aerospace and defense, and metallurgy and chemical refining. Central Asia is an emerging REE and rare metals (RM) producing region. A newly compiled inventory of REE-RM-bearing mineral occurrences and delineation of areas-of-interest indicate this region may have considerable undiscovered resources.

Transition metal complexes of some biologically active ligands; synthesis characterization and bioactivities

International Nuclear Information System (INIS)

Rehman, S.; Ali, N.; Nisar, M.

2009-01-01

Transition/representative transition metals complexes of biologically active chelating agent 1,2-dipyrolodinoethane were synthesized and characterized through spectral and analytical data. The complexes are of the formula (M(L)X/sub 2/). Where (M = Co (II), Ni (II), Cu (II), Zn (II), Hg (II) and Cd (II) and X = CI, Br, NO/sub 3/). Tetrahedral geometry has been proposed to these-metal complexes with the help of magnetic measurements, elemental analysis, chemical stoichiometry and spectroscopic data Antibacterial activity of the ligand and its metal complexes were screened against Eschereschi coli, Klebsiello pneumonia, Proteus mirabilis, Proteus vulhari, Streptococcus pneumonia, Salmonella Iyphi, Bacilh,s anthrax, Streptococcus fecalis and Staphylococcus aureus. Complexes were found to be active against Eschereschi coli, Klebsiella pneumonia, Proteus mirabilis and Proteus vulharis. (author)

Basic deuteroexchange in complexes of transition metals with nitrogen-containing aromatic heterocycles

International Nuclear Information System (INIS)

Tupitsyn, I.F.

1986-01-01

A study was made of the kinetics of deuteroexchange in the methyl group in complexes of one metal [nickel(II)] with different methyl-substituted aromatic heterocycles and in isostructural complexes of one ligand (2-methylquinoline) with different central metal atoms (Mn 2+ , Ni 2+ , Cu 2+ , Zn 2+ ). The order in which the structures of the ligands influence the rate of deuteroexchange in the complexes does not correspond qualitatively with the order of increase in the rate of deuteroexchange in the noncoordinated ligands. The rate of deuteroexchange is only weakly influenced by change in the identity of the metal complex former. A deuteroexchange mechanism is proposed and discussed. A structure arising in the course of the exchange process with transfer of electron density from the heterocyclic ligand to the metal ion forms the transition state of the reaction

Poly-functional description of metal complexation by natural organic matter: theory and practice

International Nuclear Information System (INIS)

Buffle, J.; Filella, M.; Altmann, R.S.

1995-01-01

The Differential Equilibrium Function (DEF) approach to metal complexation interpretation and prediction is compared to other models or approaches. The basic features of DEF are summarized, both from the experimental and theoretical points of view. The relation of DEF with key environmental concepts or parameters, in particular minor vs major complexing sites, the buffering intensity of natural organic matter (NOM), and their poly functional vs polyelectrolyte properties, is discussed. The relation between DEF and Freundlich isotherm is described quantitatively. The practical applications of DEF are discussed for (i) interpretation of metal complexation by NOM, and (ii) prediction of metal complexation by NOM. It is shown that DEF (i.e. sound extrapolation is possible with care). DEF cans be readily incorporated in metal species distribution codes (e.g. MINEQL). DEF is not equivalent to a molecular complexation model which describes complexation at each individual site; DEF gives a rigorous representation of complexation by NOM as a whole chemical system. (authors). 23 refs., 6 figs

IRMPD Action Spectroscopy of Alkali Metal Cation-Cytosine Complexes: Effects of Alkali Metal Cation Size on Gas Phase Conformation

NARCIS (Netherlands)

Yang, B.; Wu, R.R.; Polfer, N.C.; Berden, G.; Oomens, J.; Rodgers, M.T.

2013-01-01

The gas-phase structures of alkali metal cation-cytosine complexes generated by electrospray ionization are probed via infrared multiple photon dissociation (IRMPD) action spectroscopy and theoretical calculations. IRMPD action spectra of five alkali metal cation-cytosine complexes exhibit both

Recent advances in syntheses and biomedical applications of nano-rare earth metal-organic framework materials

Directory of Open Access Journals (Sweden)

Xin Pengyan

2017-12-01

Full Text Available In recent years,the syntheses of nano-rare earth metal-organic framework (MOF materials and their applications in biomedicine,especially in the diagnosis and treatment of cancer have attracted extensive attentions.On the one hand,nano-rare earth MOFs,which have unique optical and magnetic properties,are promising multimodal imaging contrast agents for biomedical imaging,such as fluorescence imaging and magnetic resonance imaging.On the other hand,nano-rare earth MOFs have various compositions and structures,and excellent intrinsic properties such as large specific surface area,high pore volume and tunable pore size,which enable them to perform as promising nanoplatforms for drug delivery.Therefore,nano-rare earth MOFs may provide a new platform for the development of diagnostic and therapeutic reagents.In this article,the recent advances in the syntheses of nano-rare earth MOFs and their applications in biomedicine are summarized.

Ibandronate metal complexes: solution behavior and antiparasitic activity.

Science.gov (United States)

Demoro, Bruno; Rostán, Santiago; Moncada, Mauricio; Li, Zhu-Hong; Docampo, Roberto; Olea Azar, Claudio; Maya, Juan Diego; Torres, Julia; Gambino, Dinorah; Otero, Lucía

2018-03-01

To face the high costs of developing new drugs, researchers in both industry and academy are looking for ways to repurpose old drugs for new uses. In this sense, bisphosphonates that are clinically used for bone diseases have been studied as agents against Trypanosoma cruzi, causative parasite of Chagas disease. In this work, the development of first row transition metal complexes (M = Co 2+ , Mn 2+ , Ni 2+ ) with the bisphosphonate ibandronate (iba, H 4 iba representing the neutral form) is presented. The in-solution behavior of the systems containing iba and the selected 3d metal ions was studied by potentiometry. Mononuclear complexes [M(H x iba)] (2-x)- (x = 0-3) and [M(Hiba) 2 ] 4- together with the formation of the neutral polynuclear species [M 2 iba] and [M 3 (Hiba) 2 ] were detected for all studied systems. In the solid state, complexes of the formula [M 3 (Hiba) 2 (H 2 O) 4 ]·6H 2 O were obtained and characterized. All obtained complexes, forming [M(Hiba)] - species under the conditions of the biological studies, were more active against the amastigote form of T. cruzi than the free iba, showing no toxicity in mammalian Vero cells. In addition, the same complexes were selective inhibitors of the parasitic farnesyl diphosphate synthase (FPPS) enzyme showing poor inhibition of the human one. However, the increase of the anti-T. cruzi activity upon coordination could not be explained neither through the inhibition of TcFPPS nor through the inhibition of TcSPPS (T. cruzi solanesyl-diphosphate synthase). The ability of the obtained metal complexes of catalyzing the generation of free radical species in the parasite could explain the observed anti-T. cruzi activity.

Reactivity of olefin and allyl ligands in π-complexes of metals

International Nuclear Information System (INIS)

Kukushkin, Yu.N.

1987-01-01

The data on reactivity of olefin and allyl ligands in transition metal (Ru, W) π-complexes, published up to 1984 are presented. Metal ion coordination of olefins causes their appreciable reactivity change. Transformations of π-olefin ligands into σ-alkyl ones, interaction of π-complexes with oxygen nucleophilic reagents, amines, halogenides and pseudohalogenides are considered

Bovine Serum Albumin Metal Complexes for Mimic of SOD

Indian Academy of Sciences (India)

Key Lab. Eco-Environment-Related Polymer Materials of Ministry of Education, Key Lab. ... scaffold and the metal complex functioned as the catalytic active center. ... small molecule.22 It is found that the antioxidative ... and absence, respectively, of the measured compound. ... monitor the interaction of metal ions with BSA.

Fate and transport of trace metals and rare earth elements in the Snake River, an AMD/ARD-impacted watershed. Montezuma, Colorado USA.

Science.gov (United States)

McKnight, D. M.; Rue, G.

2017-12-01

Recent research in Snake River Watershed, located near the historic boomtown of Montezuma and adjacent the Continental Divide in the Colorado Rocky Mountains, has revealed the distinctive occurrence of rare earth elements (REE) at high concentrations. Here the weathering of the mineralized lithology naturally generates acid rock drainage (ARD) in addition to drainage recieved from abandoned mine adits throughout the area, results in aqueous REE concentrations three orders of magnitude higher than in most major rivers. The dominant mechanism responsible for this enrichment; their dissolution from secondary and accessory mineral stocks, abundant in REEs, promoted by the low pH waters generated from geochemical weathering of disseminated sulfide minerals. While REEs behave conservatively in acidic conditions, as well as in the presence of stabilizing ligands such as sulfate, downstream circumneutral inputs from pristine streams and a rising pH are resulting in observed fractional losses of heavy rare earth elements as well as partitioning towards colloidal and solid phases. These finding in combination with the established role of dissolved organic matter (DOM) in binding with both trace metals and REEs, suggest that competitive interactions, complexation, and scavenging are likely contributing to these proportional losses. However, outstanding questions yet remain regarding the effects of an increasing flux of trace metals as well as REEs from the Snake River Watershed into Dillon Reservoir, a major drinking water supply for the City of Denver, in part due to hydroclimatological drivers that are enhancing geochemical weathering and reducing groundwater recharge in alpine areas across the Colorado Rockies. Based on these findings also we seek to broaden this body of work to further investigate the behavior of rare earth elements (REE) in other aquatic environment as well the influence of trace metals, DOM, and pH in altering their reactivity and subsequent watershed

Contribution to the theoretical study of metallic systems containing rare earths: hyperfine interactions and exchange coupling

International Nuclear Information System (INIS)

Troper, A.

1978-01-01

A theoretical study involving rare earth impurities, which were embedded in transition metals (s-p or noble), from the point of view of the hyperfine interactions is presented. A model was created to describe a d-resonance (Anderson-Moriya) acting on a s-p conduction band which was strongly perturbed by a slater-koster potential, used to describe the rare earths which were diluted in matrices of transition elements. (author)

Metal-isonitrile adducts for preparing radionuclide complexes

International Nuclear Information System (INIS)

Carpenter, A.P.; Linder, K.E.; Maheu, L.J.; Patz, M.A.; Thompson, J.S.; Tulip, T.H.; Subramanyam, V.

1988-01-01

An method for preparing a coordination complex of isonitrile ligand and a radioisotope of Te, Ru, Co, Pt, Re, Os, Ir, W, Re, Cr, Mo, Mn, Ni, Rh, Nb and Ta from a non-radioactive metal adduct of the isonitrile

Pesticides Curbing Soil Fertility: Effect of Complexation of Free Metal Ions

Science.gov (United States)

Kaur, Sukhmanpreet; Kumar, Vijay; Chawla, Mohit; Cavallo, Luigi; Poater, Albert; Upadhyay, Niraj

2017-07-01

Researchers have suggested that the reason behind infertility is pernicious effect of broad spectrum pesticides on non target, beneficial microorganism of soil. Here, studying the chelating effect of selective organophosphate and carbamate pesticides with essential metal ions, at all possible combinations of three different pH (4±0.05, 7±0.05 and 9±0.05) and three different temperatures (15±0.5°C, 30±0.5°C and 45±0.5°C), shows very fast rate of reaction which further increases with increase of pH and temperature. Carbonyl oxygen of carbamate and phosphate oxygen of organophosphate were found to be common ligating sites among all the complexes. Formed metal complexes were found to be highly stable and water insoluble on interaction with essential metal ions in solvent medium as well as over silica. Density functional theory (DFT) calculations not only reinforced the experimental observations, but, after a wide computational conformational analysis, unraveled the nature of the high stable undesired species that consist of pesticides complexed by metal ions from the soil. All in all, apart from the direct toxicity of pesticides, the indirect effect by means of complexation of free metal ions impoverishes the soil.

Pesticides Curbing Soil Fertility: Effect of Complexation of Free Metal Ions

KAUST Repository

Kaur, Sukhmanpreet

2017-07-04

Researchers have suggested that the reason behind infertility is pernicious effect of broad spectrum pesticides on non target, beneficial microorganism of soil. Here, studying the chelating effect of selective organophosphate and carbamate pesticides with essential metal ions, at all possible combinations of three different pH (4 ± 0.05, 7 ± 0.05 and 9 ± 0.05) and three different temperatures (15 ± 0.5°C, 30 ± 0.5°C and 45 ± 0.5°C), shows very fast rate of reaction which further increases with increase of pH and temperature. Carbonyl oxygen of carbamate and phosphate oxygen of organophosphate were found to be common ligating sites among all the complexes. Formed metal complexes were found to be highly stable and water insoluble on interaction with essential metal ions in solvent medium as well as over silica. Density functional theory (DFT) calculations not only reinforced the experimental observations, but, after a wide computational conformational analysis, unraveled the nature of the high stable undesired species that consist of pesticides complexed by metal ions from the soil. All in all, apart from the direct toxicity of pesticides, the indirect effect by means of complexation of free metal ions impoverishes the soil.

Pesticides Curbing Soil Fertility: Effect of Complexation of Free Metal Ions

KAUST Repository

Kaur, Sukhmanpreet; Kumar, Vijay; Chawla, Mohit; Cavallo, Luigi; Poater, Albert; Upadhyay, Niraj

2017-01-01

Researchers have suggested that the reason behind infertility is pernicious effect of broad spectrum pesticides on non target, beneficial microorganism of soil. Here, studying the chelating effect of selective organophosphate and carbamate pesticides with essential metal ions, at all possible combinations of three different pH (4 ± 0.05, 7 ± 0.05 and 9 ± 0.05) and three different temperatures (15 ± 0.5°C, 30 ± 0.5°C and 45 ± 0.5°C), shows very fast rate of reaction which further increases with increase of pH and temperature. Carbonyl oxygen of carbamate and phosphate oxygen of organophosphate were found to be common ligating sites among all the complexes. Formed metal complexes were found to be highly stable and water insoluble on interaction with essential metal ions in solvent medium as well as over silica. Density functional theory (DFT) calculations not only reinforced the experimental observations, but, after a wide computational conformational analysis, unraveled the nature of the high stable undesired species that consist of pesticides complexed by metal ions from the soil. All in all, apart from the direct toxicity of pesticides, the indirect effect by means of complexation of free metal ions impoverishes the soil.

Photoactivatable metal complexes: from theory to applications in biotechnology and medicine.

Science.gov (United States)

Smith, Nichola A; Sadler, Peter J

2013-07-28

This short review highlights some of the exciting new experimental and theoretical developments in the field of photoactivatable metal complexes and their applications in biotechnology and medicine. The examples chosen are based on some of the presentations at the Royal Society Discussion Meeting in June 2012, many of which are featured in more detail in other articles in this issue. This is a young field. Even the photochemistry of well-known systems such as metal-carbonyl complexes is still being elucidated. Striking are the recent developments in theory and computation (e.g. time-dependent density functional theory) and in ultrafast-pulsed radiation techniques which allow photochemical reactions to be followed and their mechanisms to be revealed on picosecond/nanosecond time scales. Not only do some metal complexes (e.g. those of Ru and Ir) possess favourable emission properties which allow functional imaging of cells and tissues (e.g. DNA interactions), but metal complexes can also provide spatially controlled photorelease of bioactive small molecules (e.g. CO and NO)--a novel strategy for site-directed therapy. This extends to cancer therapy, where metal-based precursors offer the prospect of generating excited-state drugs with new mechanisms of action that complement and augment those of current organic photosensitizers.

Byproduct metals and rare-earth elements used in the production of light-emitting diodes—Overview of principal sources of supply and material requirements for selected markets

Science.gov (United States)

Wilburn, David R.

2012-01-01

The use of light-emitting diodes (LEDs) is expanding because of environmental issues and the efficiency and cost savings achieved compared with use of traditional incandescent lighting. The longer life and reduced power consumption of some LEDs have led to annual energy savings, reduced maintenance costs, and lower emissions of carbon dioxide, sulfur dioxide, and nitrogen oxides from powerplants because of the resulting decrease in energy consumption required for lighting applications when LEDs are used to replace less-energy-efficient sources. Metals such as arsenic, gallium, indium, and the rare-earth elements (REEs) cerium, europium, gadolinium, lanthanum, terbium, and yttrium are important mineral materials used in LED semiconductor technology. Most of the world's supply of these materials is produced as byproducts from the production of aluminum, copper, lead, and zinc. Most of the rare earths required for LED production in 2011 came from China, and most LED production facilities were located in Asia. The LED manufacturing process is complex and is undergoing much change with the growth of the industry and the changes in demand patterns of associated commodities. In many respects, the continued growth of the LED industry, particularly in the general lighting sector, is tied to its ability to increase LED efficiency and color uniformity while decreasing the costs of producing, purchasing, and operating LEDs. Research is supported by governments of China, the European Union, Japan, the Republic of Korea, and the United States. Because of the volume of ongoing research in this sector, it is likely that the material requirements of future LEDs may be quite different than LEDs currently (2011) in use as industry attempts to cut costs by reducing material requirements of expensive heavy rare-earth phosphors and increasing the sizes of wafers for economies of scale. Improved LED performance will allow customers to reduce the number of LEDs in automotive, electronic

Complex demodulation in VLBI estimation of high frequency Earth rotation components

Science.gov (United States)

Böhm, S.; Brzeziński, A.; Schuh, H.

2012-12-01

The spectrum of high frequency Earth rotation variations contains strong harmonic signal components mainly excited by ocean tides along with much weaker non-harmonic fluctuations driven by irregular processes like the diurnal thermal tides in the atmosphere and oceans. In order to properly investigate non-harmonic phenomena a representation in time domain is inevitable. We present a method, operating in time domain, which is easily applicable within Earth rotation estimation from Very Long Baseline Interferometry (VLBI). It enables the determination of diurnal and subdiurnal variations, and is still effective with merely diurnal parameter sampling. The features of complex demodulation are used in an extended parameterization of polar motion and universal time which was implemented into a dedicated version of the Vienna VLBI Software VieVS. The functionality of the approach was evaluated by comparing amplitudes and phases of harmonic variations at tidal periods (diurnal/semidiurnal), derived from demodulated Earth rotation parameters (ERP), estimated from hourly resolved VLBI ERP time series and taken from a recently published VLBI ERP model to the terms of the conventional model for ocean tidal effects in Earth rotation recommended by the International Earth Rotation and Reference System Service (IERS). The three sets of tidal terms derived from VLBI observations extensively agree among each other within the three-sigma level of the demodulation approach, which is below 6 μas for polar motion and universal time. They also coincide in terms of differences to the IERS model, where significant deviations primarily for several major tidal terms are apparent. An additional spectral analysis of the as well estimated demodulated ERP series of the ter- and quarterdiurnal frequency bands did not reveal any significant signal structure. The complex demodulation applied in VLBI parameter estimation could be demonstrated a suitable procedure for the reliable reproduction of

Using metal complex-labeled peptides for charge transfer-based biosensing with semiconductor quantum dots

Science.gov (United States)

Medintz, Igor L.; Pons, Thomas; Trammell, Scott A.; Blanco-Canosa, Juan B.; Dawson, Philip E.; Mattoussi, Hedi

2009-02-01

Luminescent colloidal semiconductor quantum dots (QDs) have unique optical and photonic properties and are highly sensitive to charge transfer in their surrounding environment. In this study we used synthetic peptides as physical bridges between CdSe-ZnS core-shell QDs and some of the most common redox-active metal complexes to understand the charge transfer interactions between the metal complexes and QDs. We found that QD emission underwent quenching that was highly dependent on the choice of metal complex used. We also found that quenching traces the valence or number of metal complexes brought into close proximity of the nanocrystal surface. Monitoring of the QD absorption bleaching in the presence of the metal complex provided insight into the charge transfer mechanism. The data suggest that two distinct charge transfer mechanisms can take place. One directly to the QD core states for neutral capping ligands and a second to surface states for negatively charged capping ligands. A basic understanding of the proximity driven charge-transfer and quenching interactions allowed us to construct proteolytic enzyme sensing assemblies with the QD-peptide-metal complex conjugates.

Synthesis and antimalarial activity of metal complexes of cross-bridged tetraazamacrocyclic ligands.

Science.gov (United States)

Hubin, Timothy J; Amoyaw, Prince N-A; Roewe, Kimberly D; Simpson, Natalie C; Maples, Randall D; Carder Freeman, TaRynn N; Cain, Amy N; Le, Justin G; Archibald, Stephen J; Khan, Shabana I; Tekwani, Babu L; Khan, M O Faruk

2014-07-01

Using transition metals such as manganese(II), iron(II), cobalt(II), nickel(II), copper(II), and zinc(II), several new metal complexes of cross-bridged tetraazamacrocyclic chelators namely, cyclen- and cyclam-analogs with benzyl groups, were synthesized and screened for in vitro antimalarial activity against chloroquine-resistant (W2) and chloroquine-sensitive (D6) strains of Plasmodium falciparum. The metal-free chelators tested showed little or no antimalarial activity. All the metal complexes of the dibenzyl cross-bridged cyclam ligand exhibited potent antimalarial activity. The Mn(2+) complex of this ligand was the most potent with IC50s of 0.127 and 0.157μM against the chloroquine-sensitive (D6) and chloroquine-resistant (W2) P. falciparum strains, respectively. In general, the dibenzyl hydrophobic ligands showed better anti-malarial activity compared to the activity of monobenzyl ligands, potentially because of their higher lipophilicity and thus better cell penetration ability. The higher antimalarial activity displayed by the manganese complex for the cyclam ligand in comparison to that of the cyclen, correlates with the larger pocket of cyclam compared to that of cyclen which produces a more stable complex with the Mn(2+). Few of the Cu(2+) and Fe(2+) complexes also showed improvement in activity but Ni(2+), Co(2+) and Zn(2+) complexes did not show any improvement in activity upon the metal-free ligands for anti-malarial development. Published by Elsevier Ltd.

Metal distributions in complexes with Chlorella vulgaris in seawater and wastewater

Energy Technology Data Exchange (ETDEWEB)

Pascucci, P.R.; Kowalak, A.D.

1999-10-01

Divalent cadmium (Cd), copper (Cu), iron (Fe), nickel (Ni), lead (Pb), and zinc (Zn) simultaneous complexes with an algal biomass Chlorella vulgaris were studied for bioremediation purposes in various aqueous media: distilled-deionized water (DDIW), seawater, nuclear-reactor pool water, and process wastewater. Reactions were monitored using various dry masses of algae at constant temperature and constant metal concentrations for reaction times ranging from 0 to 150 minutes. Complexes occurred within 30 minutes and reached a steady state after 80 to 120 minutes. Distribution constants (K{prime}{sub d}) were calculated for the complexes and relative orders of K{prime}{sub d} were reported. The K{prime}{sub d} are used to evaluate relative efficiency of metal remediation from waters. Lead, Cu, and Ni complexes had the greatest K{prime}{sub d} values and those metals were most efficiently removed from these waters. Zinc and Fe formed the most labile complexes. The order of K{prime}{sub d} values for complexes in DDIW was Pb > Cu > Cd > Zn, then Cu > Cd > Zn in seawater, Cd > Cu > Zn in reactor pool water, and Ni > Cd > Cu > Zn > Fe in wastewater. C. vulgaris biomass may potentially be used as an alternative to traditional water treatment methods for simultaneous extraction of metals from seawater, process wastewater, or drinking water.

Determination of aminoglycoside antibiotics using complex compounds of chromotropic acid bisazoderivatives with rare earth ions

International Nuclear Information System (INIS)

Alykov, N.M.

1981-01-01

Studies of complex formation of bisazo derivatives of chromotropic acid with rare earth ions and aminoglycoside antibiotics have made it possible to choose carboxyarsenazo, orthanyl R and carboxynitrazo as highly sensitive reagents for determining aminoglycoside antibiotics. Conditions have been found for the formation of precipitates of different-ligand complexes containing rare earth ions, bisazo derivatives of chromotropic acid and aminogylcoside antibiotics. A procedure has been worked out of determining the antibiotics in biological samples with carboxyarsenazo [ru

Hydrometallurgical separation of rare earth elements, cobalt and nickel from spent nickel-metal-hydride batteries

Science.gov (United States)

Rodrigues, Luiz Eduardo Oliveira Carmo; Mansur, Marcelo Borges

The separation of rare earth elements, cobalt and nickel from NiMH battery residues is evaluated in this paper. Analysis of the internal content of the NiMH batteries shows that nickel is the main metal present in the residue (around 50% in weight), as well as potassium (2.2-10.9%), cobalt (5.1-5.5%), rare earth elements (15.3-29.0%) and cadmium (2.8%). The presence of cadmium reveals that some Ni-Cd batteries are possibly labeled as NiMH ones. The leaching of nickel and cobalt from the NiMH battery powder with sulfuric acid is efficient; operating variables temperature and concentration of H 2O 2 has no significant effect for the conditions studied. A mixture of rare earth elements is separated by precipitation with NaOH. Finally, solvent extraction with D2EHPA (di-2-ethylhexyl phosphoric acid) followed by Cyanex 272 (bis-2,4,4-trimethylpentyl phosphinic acid) can separate cadmium, cobalt and nickel from the leach liquor. The effect of the main operating variables of both leaching and solvent extraction steps are discussed aiming to maximize metal separation for recycling purposes.

Effects of rare earth metals addition on the resistance to pitting corrosion of super duplex stainless steel - Part 1

International Nuclear Information System (INIS)

Kim, Soon-Tae; Jeon, Soon-Hyeok; Lee, In-Sung; Park, Yong-Soo

2010-01-01

To elucidate the effects of rare earth metals addition on the resistance to pitting corrosion of super duplex stainless steel, a metallographic examination, potentiodynamic and potentiostatic polarization tests, a SEM-EDS and a SAM analysis of inclusion, austenite phase and ferrite phase were conducted. The addition of rare earth metals to the base alloy led to the formation of (Mn, Cr, Si, Al, Ce) oxides and (Mn, Cr, Si, Ce) oxides, which improved the resistance to pitting corrosion and caused a decrease in the preferential interface areas for the initiation of the pitting corrosion.

Biotransformation of uranium and transition metal citrate complexes by clostridia

International Nuclear Information System (INIS)

Francis, A.J.; Joshi-Tope, G.A.; Dodge, C.J.; Gillow, J.B.

2002-01-01

Clostridium sphenoides, which uses citric acid as its sole carbon source, metabolized equimolar Fe(III)-citrate with the degradation of citric acid and the reduction of Fe(III) to Fe(II), but not the U(VI)-citrate complex. However, in the presence of excess citric acid or added glucose it was reduced to U(IV)-citrate. In contrast, Clostridium sp., which ferments glucose but not citrate, reduced Fe(III)-citrate to Fe(II)-citrate and U(VI)-citrate to U(IV)-citrate only when supplied with glucose. These results show that complexed uranium is readily accessible as an electron acceptor despite the bacterium's inability to metabolize the organic ligand complexed to the actinide. These results also show that the metabolism of the metal-citrate complex depends upon the type of complex formed between the metal and citric acid. Fe(III) forms a bidentate complex with citric acid and was metabolized, whereas U forms a binuclear complex with citric acid and was recalcitrant. (author)

Synthesis, spectral, thermal, potentiometric and antimicrobial studies of transition metal complexes of tridentate ligand

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Sarika M. Jadhav

2014-01-01

Full Text Available A series of metal complexes of Cu(II, Ni(II, Co(II, Fe(III and Mn(II have been synthesized with newly synthesized biologically active tridentate ligand. The ligand was synthesized by condensation of dehydroacetic acid (3-acetyl-6-methyl-(2H pyran-2,4(3H-dione or DHA, o-phenylene diamine and fluoro benzaldehyde and characterized by elemental analysis, molar conductivity, magnetic susceptibility, thermal analysis, X-ray diffraction, IR, 1H-NMR, UV–Vis spectroscopy and mass spectra. From the analytical data, the stoichiometry of the complexes was found to be 1:2 (metal:ligand with octahedral geometry. The molar conductance values suggest the non-electrolyte nature of metal complexes. The IR spectral data suggest that the ligand behaves as a dibasic tridentate ligand with ONN donor atoms sequence towards central metal ion. Thermal behaviour (TG/DTA and kinetic parameters calculated by the Coats–Redfern and Horowitz–Metzger method suggest more ordered activated state in complex formation. To investigate the relationship between stability constants of metal complexes and antimicrobial activity, the dissociation constants of Schiff bases and stability constants of their binary metal complexes have been determined potentiometrically in THF–water (60:40% solution at 25 ± 1 °C and at 0.1 M NaClO4 ionic strength. The potentiometric study suggests 1:1 and 1:2 complexation. Antibacterial and antifungal activities in vitro were performed against Staphylococcus aureus, Escherichia coli and Aspergillus niger, Trichoderma, respectively. The stability constants of the metal complexes were calculated by the Irving–Rosotti method. A relation between the stability constant and antimicrobial activity of complexes has been discussed. It is observed that the activity enhances upon complexation and the order of antifungal activity is in accordance with stability order of metal ions.

Using Google Earth Surface Metrics to Predict Plant Species Richness in a Complex Landscape

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Sebastián Block

2016-10-01

Full Text Available Google Earth provides a freely available, global mosaic of high-resolution imagery from different sensors that has become popular in environmental and ecological studies. However, such imagery lacks the near-infrared band often used in studying vegetation, thus its potential for estimating vegetation properties remains unclear. In this study, we assess the potential of Google Earth imagery to describe and predict vegetation attributes. Further, we compare it to the potential of SPOT imagery, which has additional spectral information. We measured basal area, vegetation height, crown cover, density of individuals, and species richness in 60 plots in the oak forests of a complex volcanic landscape in central Mexico. We modelled each vegetation attribute as a function of surface metrics derived from Google Earth and SPOT images, and selected the best-supported linear models from each source. Total species richness was the best-described and predicted variable: the best Google Earth-based model explained nearly as much variation in species richness as its SPOT counterpart (R2 = 0.44 and 0.51, respectively. However, Google Earth metrics emerged as poor predictors of all remaining vegetation attributes, whilst SPOT metrics showed potential for predicting vegetation height. We conclude that Google Earth imagery can be used to estimate species richness in complex landscapes. As it is freely available, Google Earth can broaden the use of remote sensing by researchers and managers in low-income tropical countries where most biodiversity hotspots are found.

Effects of Rare Earth Metal Addition on Wear Resistance of Chromium-Molybdenum Cast Steel

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Kasinska J.

2017-09-01

Full Text Available This paper discusses changes in the microstructure and abrasive wear resistance of G17CrMo5-5 cast steel modified with rare earth metals (REM. The changes were assessed using scanning microscopy. The wear response was determined in the Miller test to ASTM G75. Abrasion tests were supplemented with the surface profile measurements of non-modified and modified cast steel using a Talysurf CCI optical profilometer. It was demonstrated that the modification substantially affected the microstructure of the alloy, leading to grain size reduction and changed morphology of non-metallic inclusions. The observed changes in the microstructure resulted in a three times higher impact strength (from 33 to 99 kJ/cm2 and more than two times higher resistance to cracking (from 116 to 250 MPa. The following surface parameters were computed: Sa: Arithmetic mean deviation of the surface, Sq: Root-mean-square deviation of the surface, Sp: Maximum height of the peak Sv: Maximum depth of the valley, Sz: Ten Point Average, Ssk: Asymmetry of the surface, Sku: Kurtosis of the surface. The findings also indicated that the addition of rare earth metals had a positive effect on the abrasion behaviour of G17CrMo5-5 cast steel.

Physicochemical and biological properties of new steroid metal complexes

International Nuclear Information System (INIS)

Huber, R.

1980-04-01

The aim of this investigation was to prepare stable steroid metal chelates by chemical conversion of the natural steroid hormones testerone, 5α-dihydrotestosterone (5α-DHT) and estradiol and to characterize these by means of their spectroscopic and other physico-chemical properties. In addition, various measuring techniques for the qualitative and quantitative study of complex stabilities and hydrolytic properties were employed. The distribution of some tritiated steroid metal complexes in the tissues of rats was tested using whole animal autoradiography, mainly with a view to identifying whether selective concentration occurs in certain organs. (orig.) [de

N-heterocyclic carbene metal complexes as bio-organometallic antimicrobial and anticancer drugs.

Science.gov (United States)

Patil, Siddappa A; Patil, Shivaputra A; Patil, Renukadevi; Keri, Rangappa S; Budagumpi, Srinivasa; Balakrishna, Geetha R; Tacke, Matthias

2015-01-01

Late transition metal complexes that bear N-heterocyclic carbene (NHC) ligands have seen a speedy growth in their use as both, metal-based drug candidates and potentially active homogeneous catalysts in a plethora of C-C and C-N bond forming reactions. This review article focuses on the recent developments and advances in preparation and characterization of NHC-metal complexes (metal: silver, gold, copper, palladium, nickel and ruthenium) and their biomedical applications. Their design, syntheses and characterization have been reviewed and correlated to their antimicrobial and anticancer efficacies. All these initial discoveries help validate the great potential of NHC-metal derivatives as a class of effective antimicrobial and anticancer agents.

Preparation and characterisation of some transition metal complexes of niacinamide (vitamin b3)

International Nuclear Information System (INIS)

Hasan, M.M.; Hossain, M.E.; Halim, M.E.

2015-01-01

Niacinamide forms metal complexes of general formula (M(C/sub 6/H/sub 6/N/sub 2/O)2)Cl/sub 2/; where M = Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) in the aqueous medium. The complexes were formulated by comparing the experimental and calculated data for C, H, N and metal. The prepared complexes were characterized by different physicochemical methods. The UV-vis, FTIR spectral analysis and thermo gravimetric analysis (TGA). TGA of these complexes have been discussed. Magnetic susceptibility values indicate that all complexes except Zn complex are paramagnetic in nature. The redox properties of the metal ions in the Mn, Cu and Zn complexes have been discussed from the cyclic voltammetric studies. In all cases the systems are quasi reversible. (author)

Metal complexes in cancer therapy – an update from drug design perspective

Directory of Open Access Journals (Sweden)

Ndagi U

2017-03-01

Full Text Available Umar Ndagi, Ndumiso Mhlongo, Mahmoud E Soliman Molecular Modelling and Drug Design Research Group, School of Health Sciences, University of KwaZulu-Natal, Westville, Durban, South Africa Abstract: In the past, metal-based compounds were widely used in the treatment of disease conditions, but the lack of clear distinction between the therapeutic and toxic doses was a major challenge. With the discovery of cisplatin by Barnett Rosenberg in 1960, a milestone in the history of metal-based compounds used in the treatment of cancers was witnessed. This forms the foundation for the modern era of the metal-based anticancer drugs. Platinum drugs, such as cisplatin, carboplatin and oxaliplatin, are the mainstay of the metal-based compounds in the treatment of cancer, but the delay in the therapeutic accomplishment of other metal-based compounds hampered the progress of research in this field. Recently, however, there has been an upsurge of activities relying on the structural information, aimed at improving and developing other forms of metal-based compounds and nonclassical platinum complexes whose mechanism of action is distinct from known drugs such as cisplatin. In line with this, many more metal-based compounds have been synthesized by redesigning the existing chemical structure through ligand substitution or building the entire new compound with enhanced safety and cytotoxic profile. However, because of increased emphasis on the clinical relevance of metal-based complexes, a few of these drugs are currently on clinical trial and many more are awaiting ethical approval to join the trial. In this review, we seek to give an overview of previous reviews on the cytotoxic effect of metal-based complexes while focusing more on newly designed metal-based complexes and their cytotoxic effect on the cancer cell lines, as well as on new approach to metal-based drug design and molecular target in cancer therapy. We are optimistic that the concept of selective

Melt cationic and anionic composition effect on titanium group metal corrosion in halogenides of alkali earths

International Nuclear Information System (INIS)

Tkhaj, V.; Kovalik, O.Yu.; Dikunov, Yu.G.; P'yankova, S.P.

1997-01-01

A study was made on interaction of titanium group metals with melts of chlorides and chloride-fluorides of alkaline earth metals and magnesium. It was revealed that the rate of metal corrosion increased from BaCl 2 2 2 2 in chloride series. It is explained by amplification of oxidation activity of salt cation in the series: Ba 2+ 2+ 2+ 2+ . It was also determined that corrosion rate of titanium exceeded the one of zirconium and hafnium, became reducing power of titanium was the highest in the given group

Crystal fields in Sc, Y, and the heavy-rare-earth metals Tb, Dy, Ho, Er, Tm, and Lu

International Nuclear Information System (INIS)

Touborg, P.

1977-01-01

Experimental investigations of the magnetic poperties of dilute alloys of the rare-earth solutes Tb, Dy, Ho, Er, and Tm in the nonmagnetic hosts Lu, Y, and Sc have been performed. These measurements, which include and supplement earlier published results, have been analyzed and crystal-field parameters for all these 15 alloy systems deduced. The consistency of the parameters was confirmed by a variety of magnetic measurements, including neutron spectroscopy. Crystal-field parameters have also been derived for the ions in pure magnetic rare-earth metals and their alloys using the results for the dilute alloys supplemented with paramagnetic measurements up to high temperatures on the concentrated systems. Mean values and standard deviations of the higher-order crystal-field parameters for all Y and Lu alloys are B 40 /β = 6.8 +- 0.9 K, B 60 /γ = 13.6 +- 0.7 K, and B 66 /γ = (9.7 +- 1.1) B 60 /γ. These values: with the inaccuracies somewhat increased: are expected to be representative also for the magnetic rare-earth metals. For rare-earth ions in the Sc host the values B 40 /β = 9.9 +- 1.9 K, B 60 /γ = 19.8 +- 1.5 K, and B 66 /γ = (9.4 +- 0.9) B 60 /γ were deduced. B 20 /α is a host-sensitive parameter which has the average values of -102.7, -53.4, and 29.5 K for rare-earth ions in Y, Lu, and Sc, respectively. There is also evidence that this parameter varies with the solute. B 20 /α for ions in the pure magnetic rare-earth metals and their alloys shows a linear variation with c/a ratio characteristic of each ion. The results indicate a contribution from anisotropic exchange to the high-temperature paramagnetic anisotropy of approximately 20% for Tb, Dy, Ho, and Er, and approximately 10% for Tm

MECHANISMS OF THE COMPLEX FORMATION BY d-METALS ON POROUS SUPPORTS AND THE CATALYTIC ACTIVITY OF THE FORMED COMPLEXES IN REDOX REACTIONS

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T. L. Rakitskaya

2015-11-01

Full Text Available The catalytic activity of supported complexes of d metals in redox reactions with participation of gaseous toxicants, PH3, CO, O3, and SO2, depends on their composition. Owing to the variety of physicochemical and structural-adsorption properties of available supports, their influence on complex formation processes, the composition and catalytic activity of metal complexes anchored on them varies over a wide range. The metal complex formation on sup-ports with weak ion-exchanging properties is similar to that in aqueous solutions. In this case, the support role mainly adds up to the ability to reduce the activity of water adsorbed on them. The interaction between a metal complex and a support surface occurs through adsorbed water molecules. Such supports can also affect complex formation processes owing to protolytic reactions on account of acidic properties of sorbents used as supports. The catalytic activity of metal complexes supported on polyphase natural sorbents considerably depends on their phase relationship. In the case of supports with the nonsimple structure and pronounced ion-exchanging properties, for instance, zeolites and laminar silicates, it is necessary to take into account the variety of places where metal ions can be located. Such location places determine distinctions in the coordination environment of the metal ions and the strength of their bonding with surface adsorption sites and, therefore, the catalytic activity of surface complexes formed by theses metal ions. Because of the energy surface inhomogeneity, it is important to determine a relationship between the strength of a metal complex bonding with a support surface and its catalytic activity. For example, bimetallic complexes are catalytically active in the reactions of oxidation of the above gaseous toxicants. In particular, in the case of carbon monoxide oxidation, the most catalytic activity is shown by palladium-copper complexes in which copper(II is strongly

Studies on mixed ligand complexes of adenine and xanthine with some rare earth ions

International Nuclear Information System (INIS)

Rastogi, P.R.; Singh, Mamta; Nayan, Ram

1993-01-01

Interactions of 6-aminopurine (adenine, HA) and 2,6-dihydroxypurine (xanthine, HB) with trivalent rare earth ions Y, Tb, Dy, Ho, Er and Tm, have been studied by pH-titration methods in aqueous solution at 20 o (μ = 0.1 M KNO 3 ). The ligands in their mixtures with tripositive rare earth ions (M 3+ ) form a number of mixed ligand complexes, M 3+ -adenine-xanthine, M 3+ -(adenine) 2 -xanthine, M 3+ -adenine-(xanthine) 2 in addition to the binary complexes, M 3+ -(adenine), M 3+ -(adenine) 2 , M 3+ -(adenine) 3 , M 3+ -(xanthine), M 3+ -(xanthine) 2 and M 3+ -(xanthine) 3 . The stability constants of these complexes have been evaluated and the results discussed. (author). 13 refs., 1 fig., 1 tab

Nitridomanganates of alkaline-earth metals. Synthesis, structure, and physical properties

Energy Technology Data Exchange (ETDEWEB)

Ovchinnikov, Alexander

2016-12-02

The main goal of the present work was the synthesis of alkaline-earth nitridomanganates (AE{sub x}Mn{sub y}N{sub z}) with extended anionic structures and the characterization of their electronic and magnetic properties. Up to now, only compounds with isolated nitridomanganate anions have been reported in the discussed ternary systems. A systematic exploratory synthesis, employing high-temperature treatment of AE nitrides and Mn under controlled N2 pressure, yielded more than ten new nitridomanganates. Their crystal structures contain anionic building blocks of different dimensionalities, ranging from isolated species to three-dimensional frameworks. In general, the formation of Mn-rich compositions was found to be driven by the emergence of Mn-Mn interactions, which creates a link between nitridometalates and transition-metal-rich binary nitrides. The obtained nitridomanganates display a plethora of interesting phenomena, such as large spin-orbit coupling, magnetic frustration, quenching of magnetism due to Mn-Mn interactions, and metal-insulator transition.

40 CFR Appendix B to Part 414 - Complexed Metal-Bearing Waste Streams

Science.gov (United States)

2010-07-01

... 414—Complexed Metal-Bearing Waste Streams Chromium Azo dye intermediates/Substituted diazonium salts + coupling compounds Vat dyes Acid dyes Azo dyes, metallized/Azo dye + metal acetate Acid dyes, Azo...

Influence of a solvent on thermodynamics of electrolytic dissociation of simple and complex rare earth salts

Energy Technology Data Exchange (ETDEWEB)

Gorodyskij, A.V.; Fialkov, Yu.Ya.; Chernyj, D.B. (AN Ukrainskoj SSR, Kiev. Inst. Obshchej i Neorganicheskoj Khimii; Kievskij Politekhnicheskij Inst. (Ukrainian SSR))

1982-03-01

Influence of the double mixed solvent on thermodynamic characteristics of ionic migration of lanthanum, neodymium, europium and dysprosium chlorides as well as their phenanthroline complexes is considered. Decrease of lambdasub(c) of simple and complex rare earth salts in the lanthanum, neodymium-europium-dysprosium series as explained by increase of solvation degree, associated with lanthanum compression. It is shown that increase of methanol or propanol content results in exothermicity decrease of the ionic migration process. The temperature constituents of enthalpy and entropy of dissociation of the simple and complex rare earth salts are presented.

Metal ion separations with proton-ionizable Lariat Ethers and their polymers

International Nuclear Information System (INIS)

Bartsch, R.A.

1993-01-01

The preparation of novel and specific organic complexing agents may lead to the development of new separation systems for aqueous metal ions. Thus the introduction of highly lipophilic oximes led to the current utilization of these compounds as commercial extractants for the hydrometallurgy of nonferrous metals. Crown ethers (macrocyclic polyethers) have been employed in the laboratory-scale solvent extraction of alkali-metal, alkaline-earth, and other metal cations into organic phases. Attachment of side arms to crown ethers gives lariat ethers. The presence of one or more potential coordination sites in the side arm of the lariat ether may produce substantial changes in the selectivity and efficiency of metal ion complexation. It has been demonstrated that concomitant transfer of an aqueous phase anion into the organic medium is not required for metal ion extraction. This factor is of immense importance to potential practical applications of these proton-ionizable crown ethers in which the common, hard, aqueous phase anions would be involved. Another advantage of proton-ionizable lariat ethers is the ease with which extracted metal ions may be stripped from the organic phase by shaking with aqueous mineral acid. Thus both metal ion extraction and stripping are facilitated by pendent proton-ionizable groups. Most of the hazardous metal ion species in the Hanford Site tank wastes are members of the alkali-metal, alkaline-earth, lanthanide, and actinide families. These hard metal ion species prefer association with hard donor atoms, such as oxygens. Therefore, crown and lariat ethers are well-suited for complexation with such metal ion species

The preparation and use of metal salen complexes derived from cyclobutane diamine

Science.gov (United States)

Patil, Smita

The helix is an important chiral motif in nature, there is increasing development in field of helical transition metal complexes and related supramolecular structures. Hence, the goals of this work are to apply the principles of helicity in order to produce metal complexes with predictable molecular shapes and to study their properties as asymmetric catalysts. Computational studies suggest that the (1R,2 R)-cyclobutyldiamine unit can produce highly twisted salen complexes with a large energy barrier between the M and P helical forms. To test this prediction, the tartrate salt of (1R,2R)-cyclobutyldiamine was synthesized and condensed with a series of saliclaldehydes to produce novel salen ligands. The salicylaldehydes chosen have extended phenanthryl or benz[a]anthryl sidearms to encourage formation of helical coordination complexes. These ligands were metallated with zinc, iron and manganese salts to produce salen metal complexes which were characterized by NMR analysis, high-resolution mass spectrometry, and IR spectroscopy. A second ligand type, neutral bis(pyridine-imine) has also been synthesized from (1R,2R)-cyclobutyldiamine and quinolylaldehydes. The synthesis of bis(pyridine-imine) ligands was conducted using greener method, solvent assisted grinding. These ligands, in-situ with nickel metal salts, showed good catalytic activity for asymmetric Diels-Alder reactions. The third ligand type studied was chiral acid-functionalized Schiff-base ligands. These were synthesized by the condensation of 3-formyl-5-methyl salicylic acid and (1R,2R)-cyclobutyldiamine. With this type of ligand, there is possibility of producing both mono and dinuclear metal complexes. In our studies, we were only able to synthesize mononuclear complexs. These were tested as catalysts for asymmetric direct Mannich-type reaction, but were found to be ineffective.

NEW RARE EARTH ELEMENT ABUNDANCE DISTRIBUTIONS FOR THE SUN AND FIVE r-PROCESS-RICH VERY METAL-POOR STARS

International Nuclear Information System (INIS)

Sneden, Christopher; Lawler, James E.; Den Hartog, Elizabeth A.; Cowan, John J.; Ivans, Inese I.

2009-01-01

We have derived new abundances of the rare earth elements Pr, Dy, Tm, Yb, and Lu for the solar photosphere and for five very metal-poor, neutron-capture r-process-rich giant stars. The photospheric values for all five elements are in good agreement with meteoritic abundances. For the low-metallicity sample, these abundances have been combined with new Ce abundances from a companion paper, and reconsideration of a few other elements in individual stars, to produce internally consistent Ba, rare earth, and Hf (56 ≤ Z ≤ 72) element distributions. These have been used in a critical comparison between stellar and solar r-process abundance mixes.

Redox reactions in rare earth chloride molten electrolytes

International Nuclear Information System (INIS)

Khokhlov, V.A.; Novoselova, A.V.; Nikolaeva, E.V.; Tkacheva, O.Yu.; Salyulev, A.B.

2007-01-01

Rare earth (REM, Ln) solutions in chloride melts including MCI+LnCl 3 mixtures, where M - alkali metals, were investigated by potentiometry, voltammetry, conductometry in wide concentration and temperature intervals. Findings present complete and trusty information on the valent state of rare earths, structure and composition of complex ions affecting essentially on properties of electrolytes. It is demonstrated that the coexistence of rare earth ions with different oxidation level formed as a result of possible redox reactions: 2Ln 3+ + Ln ↔3Ln 2+ , Ln 2+ + Ln↔2Ln + and nM + + Ln↔nM + Ln n+ appears sharply in thermodynamic and transport properties of molten Ln-LnCl 3 and Ln-LnCl 3 -MCl systems [ru

Molybdenum/alkali metal/ethylene glycol complexes useful as epoxidation catalysts

International Nuclear Information System (INIS)

Marquis, E.T.; Sanderson, J.R.; Keating, K.P.

1987-01-01

This patent describes a clear, storage stable solution of a molybdenum/alkali metal/ethylene glycol complex in ethylene glycol made by the process comprising: reacting at an elevated temperature between about 25 0 and 150 0 C a solid ammonium molybdate or a hydrate thereof and a solid alkali metal molybdate or a hydrate thereof with ethylene glycol, such that the ratio of moles of ethylene glycol to total gram atoms of molybdenum in the molybdates ranges from about 7:10 to 10:1, and the ratio of gram atoms of molybdenum in the ammonium molybdate or hydrate thereof to gram atoms of molybdenum in the alkali metal molybdate is from about 1:1 to about 20:1 to thereby provide a reaction product composed of a solution of an alkali metal-containing complex of molybdenum, alkali metal and ethylene glycol and by-products, including water, in the ethylene glycol and subsequently stripping the solution at a reduced pressure to remove from about 5 to about 25% of the reaction product, as distillate, to thereby provide a storage stable solution of the complex in the ethylene glycol having a molybdenum content of about 6 wt. % to about 20 wt. %, a water concentration of about 0.1 wt. % to about 6 wt. % and an acid number of more than about 60

Rare earth elements and critical metal content of extracted landfilled material and potential recovery opportunities

Energy Technology Data Exchange (ETDEWEB)

Gutiérrez-Gutiérrez, Silvia C.; Coulon, Frédéric; Jiang, Ying; Wagland, Stuart, E-mail: s.t.wagland@cranfield.ac.uk

2015-08-15

Highlights: • Samples from multiple core drills were obtained from 4× landfill sites in the UK. • Each sample analysed for rare earth elements, critical metals and valuable metals. • Two stage microwave digestion method ensuring high yield. • High quantities of copper and aluminium were observed in the soil layers of landfill. • Across 4× landfills aluminium and copper present has a value of around $400 million. - Abstract: Rare earth elements (REEs), Platinum group metals (PGMs) and other critical metals currently attract significant interest due to the high risks of supply shortage and substantial impact on the economy. Their uses in many applications have made them present in municipal solid waste (MSW) and in commercial and industrial waste (C&I), since several industrial processes produce by-products with high content of these metals. With over 4000 landfills in the UK alone, the aim of this study was to assess the existence of these critical metals within landfills. Samples collected from four closed landfills in UK were subjected to a two-step acid digestion to extract 27 metals of interest. Concentrations across the four landfill sites were 58 ± 6 mg kg{sup −1} for REEs comprising 44 ± 8 mg kg{sup −1} for light REEs, 11 ± 2 mg kg{sup −1} for heavy REEs and 3 ± 1 mg kg{sup −1} for Scandium (Sc) and 3 ± 1.0 mg kg{sup −1} of PGMs. Compared to the typical concentration in ores, these concentrations are too low to achieve a commercially viable extraction. However, content of other highly valuable metals (Al and Cu) was found in concentrations equating to a combined value across the four landfills of around $400 million, which increases the economic viability of landfill mining. Presence of critical metals will mainly depend on the type of waste that was buried but the recovery of these metals through landfill mining is possible and is economically feasible only if additional materials (plastics, paper, metallic items and other) are

Magnesium substitutions in rare-earth metal germanides with the Gd5Si4 type. Synthesis, structure determination and magnetic properties of RE5-xMgxGe4 (RE=Gd-Tm, Lu and Y)

Energy Technology Data Exchange (ETDEWEB)

Sarrao, J L [Los Alamos National Laboratory; Thompson, Joe D [Los Alamos National Laboratory; Tobash, P H [UNIV. OF DE; Bobev, S [UNIV. OF DE

2009-01-01

A series of magnesium-substituted rare-earth metal germanides with a general formula RE{sub 5-x}Mg{sub x}Ge{sub 4} (x {approx} 1.0-2.3; RE =Gd-Tm, Lu, Y) have been synthesized by high-temperature reactions and structurally characterized by single-crystal X-ray diffraction. These compounds crystallize with the common Gd{sub 5}Si{sub 4} type in the orthorhombic space group Pnma (No. 62; Z =4; Pearson's code oP36) and do not appear to undergo temperature-induced crystallographic phase transitions down to 120 K. Replacing rare-earth metal atoms with Mg, up to nearly 45 % at., reduces the valence electron count and is clearly expressed in the subtle changes of the Ge-Ge and metal-metal bonding. Magnetization measurements as a function of the temperature and the applied field reveal complex magnetic structures at cryogenic temperatures, and Curie-Weiss paramagnetic behavior at higher temperatures. The observed local moment magnetism is consistent with RE+ ground states in all cases. In the magnetically ordered phases, the magnetization cannot reach saturation in fields up to 50 kOe. The structural trends across the series and the variations of hte magnetic properties as a function of the Mg content are also discussed. KEYWORDS: Rare-earth intermetallics, germanides, crystal structure,Gd{sub 5}Si{sub 4} type.

Heterogeneous Delivery of Silicate and Metal to the Earth via Large Planetesimals

Science.gov (United States)

Marchi, S.; Canup, R. M.; Walker, R. J.

2017-12-01

Earth's mantle abundances of at least some highly siderophile elements, (HSE; Re, Os, Ir, Ru, Pt, Rh, Pd, and Au), are much higher than would result from metal-silicate equilibration during terrestrial core formation, and can be better explained as a result of late accretion of a minimum of 0.5% Earth's masses after core formation was complete. Traditional models assume that HSEs delivered by late projectiles completely mixed and chemically equilibrated with the Earth's mantle. This appears likely for undifferentiated, well-mixed projectiles, or for relatively small, differentiated projectiles. However several arguments suggest that late projectiles may have been large (> 1500 km in diameter) and differentiated, and in this case, portions of the projectile's core may merge with the Earth's core, rather than being mixed into the Earth's mantle. We investigate projectile mixing with a suite of SPH simulations of differentiated planetesimal colliding with the Earth. A range of outcomes emerge from our simulations suggesting that for large impactors (>1500 km), the delivery of HSE to the Earth's mantle may be disproportionate with the overall delivery of mass. For impacts with impact angles 60°, most of the impactor core escapes for moderate impact speeds. An implication is that the late accreted mass inferred from terrestrial HSE abundances may be a substantial underestimate, by a factor 2-5. In addition, partial mixing of projectiles result in an enrichment in mantle vs core material delivered to the bulk silicate Earth, implying substantial compositional variations in the accreted mass. Such variations could produce initially localized domains in Earth's mantle with distinct, mass independent isotopic signatures, given the isotopic variability resulting from nucleosynthetic heterogeneities among genetically diverse meteorites. In general we find that larger, low angle collisions would be more likely to produce initial mantle domains of anomalous composition

Complexes in polyvalent metal - Alkali halide melts

International Nuclear Information System (INIS)

Akdeniz, Z.; Tosi, M.P.

1991-03-01

Experimental evidence is available in the literature on the local coordination of divalent and trivalent metal ions by halogens in some 140 liquid mixtures of their halides with alkali halides. After brief reference to classification criteria for main types of local coordination, we focus on statistical mechanical models that we are developing for Al-alkali halide mixtures. Specifically, we discuss theoretically the equilibrium between (AlF 6 ) 3- and (AlF 4 ) - complexes in mixtures of AlF 3 and NaF as a function of composition in the NaF-rich region, the effect of the alkali counterion on this equilibrium, the possible role of (AlF 5 ) 2- as an intermediate species in molten cryolite, and the origin of the different complexing behaviours of Al-alkali fluorides and chlorides. We also present a theoretical scenario for processes of structure breaking and electron localization in molten cryolite under addition of sodium metal. (author). 26 refs, 2 tabs

Subthermal linewidths in photoassociation spectra of cold alkaline-earth-metal atoms

International Nuclear Information System (INIS)

Machholm, Mette; Julienne, Paul S.; Suominen, Kalle-Antti

2002-01-01

Narrow s-wave features with subthermal widths are predicted for the 1 Π g photoassociation spectra of cold alkaline-earth-metal atoms. The phenomenon is explained by numerical and analytical calculations. These show that only a small subthermal range of collision energies near threshold contributes to the s-wave features that are excited when the atoms are very far apart. The resonances survive thermal averaging, and may be detectable for Ca cooled near the Doppler cooling temperature of the 4 1 P 1 S laser-cooling transition

Properties of the triplet metastable states of the alkaline-earth-metal atoms

International Nuclear Information System (INIS)

Mitroy, J.; Bromley, M.W.J.

2004-01-01

The static and dynamic properties of the alkaline-earth-metal atoms in their metastable state are computed in a configuration interaction approach with a semiempirical model potential for the core. Among the properties determined are the scalar and tensor polarizabilities, the quadrupole moment, some of the oscillator strengths, and the dispersion coefficients of the van der Waals interaction. A simple method for including the effect of the core on the dispersion parameters is described

Electroluminescent devices based on rare-earth tetrakis β-diketonate complexes

International Nuclear Information System (INIS)

Quirino, W.G.; Legnani, C.; Santos, R.M.B. dos; Teixeira, K.C.; Cremona, M.; Guedes, M.A.; Brito, H.F.

2008-01-01

In this paper the synthesis, photoluminescence and electroluminescence investigation of the novel tetrakis β-diketonate of rare-earth complexes such as, M[Eu(dbm) 4 ] and M[Tb(acac) 4 ] with a variety of cationic ligands, M = Li + , Na + and K + have been investigated. The emission spectra of the Eu 3+ and Tb 3+ complexes displayed characteristic narrow bands arising from intraconfigurational transitions of trivalent rare-earth ions and exhibited red color emission for the Eu 3+ ion ( 5 D 0 → 7 F J , J = 0-6) and green for the Tb 3+ ion ( 5 D 4 → 7 F J , J = 6-0). The lack of the broaden emission bands arising from the ligands suggests the efficient intramolecular energy transfer from the dbm and acac ligands to Eu 3+ and Tb 3+ ions, respectively. In accordance to the expected, the values of PL quantum efficiency (η) of the emitting 5 D 0 state of the tetrakis(β-diketonate) complexes of Eu 3+ were higher compared with those tris-complexes. Therefore, organic electroluminescent (EL) devices were fabricated with the structure as follows: indium tin oxide (ITO)/hole transport layer (HTL) NPB or MTCD/emitter layer M[RE(β-diketonate) 4 ] complexes)/Aluminum (Al). All the films were deposited by thermal evaporation carried out in a high vacuum environment system. The OLED light emission was independent of driving voltage, indicating that the combination of charge carriers generates excitons within the M[RE(β-diketonate) 4 ] layers, and the energy is efficiently transferred to RE 3+ ion. As a best result, a pure red and green electroluminescent emission was observed from the Eu 3+ and Tb 3+ devices, confirmed by (X,Y) color coordinates

Mixed metal complexes of isoniazid and ascorbic acid: chelation ...

African Journals Online (AJOL)

Novel mixed complexes of isoniazid and ascorbic acid have been synthesized and characterized using infrared, electronic absorption data, elemental analysis, molar conductivity, melting point, thin layer chromatography and solubility. The metal ions involved in the complex formation are Cu2+, Zn2+ and Cd2+. The melting ...

An Experiment on Isomerism in Metal-Amino Acid Complexes.

Science.gov (United States)

Harrison, R. Graeme; Nolan, Kevin B.

1982-01-01

Background information, laboratory procedures, and discussion of results are provided for syntheses of cobalt (III) complexes, I-III, illustrating three possible bonding modes of glycine to a metal ion (the complex cations II and III being linkage/geometric isomers). Includes spectrophotometric and potentiometric methods to distinguish among the…

Density functional study of isoguanine tetrad and pentad sandwich complexes with alkali metal ions.

Science.gov (United States)

Meyer, Michael; Steinke, Thomas; Sühnel, Jürgen

2007-02-01

Isoguanine tetraplexes and pentaplexes contain two or more stacked polyads with intercalating metal ions. We report here the results of a density functional study of sandwiched isoguanine tetrad and pentad complexes consisting of two polyads with Na(+), K(+) and Rb(+) ions at the B3LYP level. In comparison to single polyad metal ion complexes, there is a trend towards increased non-planarity of the polyads in the sandwich complexes. In general, the pentad sandwiches have relatively planar polyad structures, whereas the tetrad complexes contain highly non-planar polyad building blocks. As in other sandwich complexes and in metal ion complexes with single polyads, the metal ion-base interaction energy plays an essential role. In iG sandwich structures, this interaction energy is slightly larger than in the corresponding guanine sandwich complexes. Because the base-base interaction energy is even more increased in passing from guanine to isoguanine, the isoguanine sandwiches are thus far the only examples where the base-base interaction energy is larger than the base-metal ion interaction energy. Stacking interactions have been studied in smaller models consisting of two bases, retaining the geometry from the complete complex structures. From the data obtained at the B3LYP and BH&H levels and with Møller-Plesset perturbation theory, one can conclude that the B3LYP method overestimates the repulsion in stacked base dimers. For the complexes studied in this work, this is only of minor importance because the direct inter-tetrad or inter-pentad interaction is supplemented by a strong metal ion-base interaction. Using a microsolvation model, the metal ion preference K(+) approximately Rb(+) > Na(+) is found for tetrad complexes. On the other hand, for pentads the ordering is Rb(+) > K(+) > Na(+). In the latter case experimental data are available that agree with this prediction.

Direct synthesis of metal complexes starting from zero-valent metals

Energy Technology Data Exchange (ETDEWEB)

Gojon-Zorrilla, Gabriel; Kharisov, Boris I. [Universidad Autonoma de Nuevo Leon, Monterrey, Nuevo Leon (Mexico); Garnovskii, Alexander D. [Institute of Physical and Organic Chemistry (Russian Federation)

1996-06-01

The recent (1980-1994) literature on metal-vapor synthesis of coordination and organometallic compounds is reviewed. An account is given of the high-and low-temperature reactions between free metal atoms and a large variety of substrates, mainly alkenes, alkynes, dienes, arenes, funtionalized arenes, alkyl halides {beta}-diketones and simple inorganic molecules. The main experimental methods are described, as well as the results obtained thereby. It is shown that in many instances these methods present significant advantages over conventional synthetic procedures, offering unique access to some metal complexes. [Spanish] Se reviso la literatura reciente (1980-1994) sobre la sintesis de compuestos de coordinacion y compuestos organometalicos a partir de vapores metalicos. Se examinan las reacciones de los atomos metalicos libres con una gran variedad de substratos, principalmente alquenos, alquinos, dienos, hidrocarburos aromaticos y sus derivados, haluros de alquilo y arilo, {beta}-dicetonas y moleculas inorganicas simples. Se presentan los principales metodos experimentales, asi como los resultados obtenidos; se concluye que la crisintesis presenta en muchos casos ventajas significativas sobre los procedimientos sinteticos tradicionales, constituyendo frecuentemente la unica opcion disponible.

Rare earth metals in North America; Zeldzame aardmetalen in Noord-Amerika

Energy Technology Data Exchange (ETDEWEB)

Louzada, K.

2012-11-15

The uncertain supply of rare earth metals (Rare Earth Elements) from China for the high tech industry in the U.S. is a barrier for innovation and the high-tech manufacturing industry. Many rare earths are applied in permanent magnets for sustainable energy generation and for energy storage systems in for example electric cars. Also other sectors feel the pressure of shortages. The federal government in the USA and US companies use the opportunity to encourage research into recycling, reducing the use and finding alternatives for rare earths. Canada sees in the uncertain supply and dwindling reserves in the USA and elsewhere an economic opportunity. Canada can start the development of hitherto unprofitable reserves of valuable materials. Both in the USA and Canada, the number of exploration projects in the mining industry has grown significantly [Dutch] De onzekere aanvoer van zeldzame aardmetalen (Rare Earth Elements) uit China voor de hightechindustrie vormt in de VS een hindernis voor innovatie en voor de hightech maakindustrie. Met name in permanente magneten voor duurzame energieopwekking en energieopslagsystemen voor bijvoorbeeld elektrische auto's worden veel zeldzame aardmetalen verwerkt. Ook andere sectoren staan onder druk. De federale overheid en bedrijven in de VS maken van de gelegenheid gebruik om onderzoek naar de recycling, vermindering van het gebruik en alternatieven voor zeldzame aardmetalen te stimuleren. Canada ziet de onzekere aanvoer en slinkende reserves in de VS en elders als een economische kans. Het land kan tot nu toe onrendabele voorkomens van de waardevolle materialen gaan ontwikkelen. Zowel in de VS als in Canada is het aantal exploratieprojecten in de mijnbouw aanzienlijk gegroeid.

Insights into aquatic toxicities of the antibiotics oxytetracycline and ciprofloxacin in the presence of metal: Complexation versus mixture

International Nuclear Information System (INIS)

Zhang Yu; Cai Xiyun; Lang Xianming; Qiao Xianliang; Li Xuehua; Chen Jingwen

2012-01-01

Co-contamination of ligand-like antibiotics (e.g., tetracyclines and quinolones) and heavy metals prevails in the environment, and thus the complexation between them is involved in environmental risks of antibiotics. To understand toxicological significance of the complex, effects of metal coordination on antibiotics' toxicity were investigated. The complexation of two antibiotics, oxytetracycline and ciprofloxacin, with three heavy metals, copper, zinc, and cadmium, was verified by spectroscopic techniques. The antibiotics bound metals via multiple coordination sites and rendered a mixture of various complexation speciations. Toxicity analysis indicated that metal coordination did modify the toxicity of the antibiotics and that antibiotic, metal, and their complex acted primarily as concentration addition. Comparison of EC 50 values revealed that the complex commonly was highest toxic and predominately correlated in toxicity to the mixture. Finally, environmental scenario analysis demonstrated that ignoring complexation would improperly classify environmental risks of the antibiotics. - Highlights: ► The complex of antibiotic with metal is a mixture of various complexation modes. ► Antibiotic and metal act as various combined interactions when their complexation is ignored. ► Antibiotic, metal, and their complex act as concentration addition interaction. ► Complex commonly is the highest toxicant. ► Neglecting complexation renders improper classification of risks for antibiotics. - Antibiotic, heavy metal and their complex act primarily as concentration addition interaction and the complex commonly is highest toxic.

Spin-disorder resistivity of heavy rare-earth metals from Gd to Tm: An ab-initio study

Science.gov (United States)

Glasbrenner, James; Belashchenko, Kirill

2010-03-01

Electrical resistivity of heavy rare-earth metals has a dominant contribution from thermal spin disorder scattering. In the paramagnetic state, this spin-disorder resistivity (SDR) decreases through the Gd-Tm series. Models based on the assumption of fully localized 4f states treated as S or J multiplets predict that SDR is proportional to S^2 (S is the 4f shell spin) times a quantum correction (S+1)/S or (J+1)/J. The interpretation of this correction using experimental results is ambiguous. Since the 4f bandwidth is not small compared to the multiplet splitting, it is not clear whether the 4f shells in rare-earth metals behave as if they were fully localized and have a good quantum number S or J. To address this issue, in this work we calculate the paramagnetic SDR of the rare-earth metal Gd-Tm series using a non-collinear implementation of the tight-binding linear muffin-tin orbital method. The conductance is found using the Landauer-B"uttiker approach applied to the active region of a varying size, averaging the conductance over random spin-disorder configurations and fitting its size dependence to Ohm's law. The results are compared with experiment and discussed. The sensitivity to basis set and the treatment of the 4f electrons, as well as the role of exchange enhancement in the conduction band is considered. The issue of the quantum correction is examined in light of the new results.

Multiheteromacrocycles that complex metal ions. Third progress report, 1 May 1976--30 April 1977

International Nuclear Information System (INIS)

Cram, D.J.

1977-01-01

The overall objective of this research is to design, synthesize and evaluate cyclic and polycyclic host organic compounds for their abilities to complex and lipophilize guest metal ions, their complexes and clusters. Host organic compounds consist of strategically placed solvating, coordinating and ion-pairing sites tied together by covalent bonds through hydrocarbon units around cavities shaped to be occupied by guest metal ions, or metal ions plus their ligands. Specificity in complexation is sought by matching the following properties of host and guest: cavity and metal ion sizes; geometric arrangements of binding sites; numbers of binding sites; characters of binding sites; and valences. The specific compounds synthesized and their complexing and lipophilizing properties are summarized

3d-METAL COMPLEXES WITH BARBITURIC ACID DERIVATIVES

Directory of Open Access Journals (Sweden)

T. V. Koksharova

2015-04-01

Full Text Available The various aspects of the 3d-metal complexes with barbiturates and uric acid chemistry such as composition, structure, physicochemical properties, possible fields of application – have been illustrated in this review

Use of polysulfides of alkali and alkaline-earth metals to obtain highly dispersed sulfur

International Nuclear Information System (INIS)

Massalimov, I.A.; Vikhareva, I.N.; Kireeva, M.S.

2008-01-01

Possibilities of obtaining polysulfides of alkali and alkaline earth metals (M is Na, K, Ca, Sr, Ba) in aqueous solutions were considered. The composition of the polysulfides and their concentration in solutions were found. The efficiencies of application of highly dispersed sulfur, produced from calcium polysulfide, and colloid sulfur as a fungicide were compared [ru

The adsorption kinetics of metal ions onto different microalgae and siliceous earth.

Science.gov (United States)

Schmitt, D; Müller, A; Csögör, Z; Frimmel, F H; Posten, C

2001-03-01

In the present work the adsorption kinetics of the six metal ions aluminum, zinc, mercury, lead, copper, and cadmium onto living microalgae were measured. The freshwater green microalga Scenedesmus subspicatus, the brackish water diatom Cyclotella cryptica, the seawater diatom Phaeodactylum tricornutum, and the seawater red alga Porphyridium purpureum were the subject of investigation. In most cases the adsorption rate of the metals could be well described by using the equation of the Langmuir adsorption rate expression. Inverse parameter estimation allowed the determination of the rate constants of the adsorption process and the maximum metal content of the algae. The highest values for the rate constant were obtained for Porphyridium purpureum followed by Phaeodactylum tricornutum. High values for the maximum content were obtained for Cyclotella cryptica and Scenedesmus subspicatus. The maximum rate constant was 24.21 h-1 for the adsorption of Hg to Porphyridium purpureum whereas the maximum metal content (0.243 g g-1) was obtained for Zn on Cyclotella cryptica. A comparison of these values with those obtained for the mineral siliceous earth exhibiting low maximum content and high adsorption rates reveals that the mechanism of adsorption onto the algae is a mixture of adsorption and accumulation.

Influence of strain and polycrystalline ordering on magnetic properties of high moment rare earth metals and alloys

International Nuclear Information System (INIS)

Scheunert, G; Ward, C; Hendren, W R; Bowman, R M; Lapicki, A A; Hardeman, R; Mooney, M; Gubbins, M

2014-01-01

Despite being the most suitable candidates for solenoid pole pieces in state-of-the-art superconductor-based electromagnets, the intrinsic magnetic properties of heavy rare earth metals and their alloys have gained comparatively little attention. With the potential of integration in micro and nanoscale devices, thin films of Gd, Dy, Tb, DyGd and DyTb were plasma-sputtered and investigated for their in-plane magnetic properties, with an emphasis on magnetization versus temperature profiles. Based on crystal structure analysis of the polycrystalline rare earth films, which consist of a low magnetic moment fcc layer at the seed interface topped with a higher moment hcp layer, an experimental protocol is introduced which allows the direct magnetic analysis of the individual layers. In line with the general trend of heavy lanthanides, the saturation magnetization was found to drop with increasing unit cell size. In situ annealed rare earth films exceeded the saturation magnetization of a high-moment Fe 65 Co 35 reference film in the cryogenic temperature regime, proving their potential for pole piece applications; however as-deposited rare earth films were found completely unsuitable. In agreement with theoretical predictions, sufficiently strained crystal phases of Tb and Dy did not exhibit an incommensurate magnetic order, unlike their single-crystal counterparts which have a helical phase. DyGd and DyTb alloys followed the trends of the elemental rare earth metals in terms of crystal structure and magnetic properties. Inter-rare-earth alloys hence present a desirable blend of saturation magnetization and operating temperature. (paper)

Isotope exchange between alkaline earth metal hydroxide and HTO water in the equilibrium state

International Nuclear Information System (INIS)

Imaizumi, H.; Gounome, J.; Kano, N.

1997-01-01

In order reveal to what extent tritium ( 3 H or T) can be incorporated into hydroxides, the isotope exchange reaction (OT-for-OH exchange reaction) between each alkaline earth metal hydroxide (M(OH) 2 ), where M means alkaline earth metal (M=Ca, Sr or Ba) and HTO water was observed homogeneously at 30 deg C under equilibrium after mixing. Consequently, the followings were obtained: a quantitative relation between the electronegativity of each M ion and the ability (of the M ion) incorporating OT - into the M hydroxide can be found and the ability is small when the temperature is high, the exchange rate for the OT-for-OH exchange reaction is small when the electronegativity of the M ion in the M hydroxide is great, as for the dissociation of HTO water, it seems that formula (HTO ↔ T + + OH - ) is more predominant than the formula (HTO ↔H + + OT - ) when the temperature is high and the method used in this work is useful to estimate the reactivity of a certain alkaline material. (author)

A volatile topic: Parsing out the details of Earth's formation through experimental metal-silicate partitioning of volatile and moderately volatile elements

Science.gov (United States)

Mahan, B. M.; Siebert, J.; Blanchard, I.; Badro, J.; Sossi, P.; Moynier, F.

2017-12-01

Volatile and moderately volatile elements display different volatilities and siderophilities, as well as varying sensitivity to thermodynamic controls (X, P, T, fO2) during metal-silicate differentiation. The experimental determination of the metal-silicate partitioning of these elements permits us to evaluate processes controlling the distribution of these elements in Earth. In this work, we have combined metal-silicate partitioning data and results for S, Sn, Zn and Cu, and input these characterizations into Earth formation models. Model parameters such as source material, timing of volatile delivery, fO2 path, and degree of impactor equilibration were varied to encompass an array of possible formation scenarios. These models were then assessed to discern plausible sets of conditions that can produce current observed element-to-element ratios (e.g. S/Zn) in the Earth's present-day mantle, while also satisfying current estimates on the S content of the core, at no more than 2 wt%. The results of our models indicate two modes of accretion that can maintain chondritic element-to-element ratios for the bulk Earth and can arrive at present-day mantle abundances of these elements. The first mode requires the late addition of Earth's entire inventory of these elements (assuming a CI-chondritic composition) and late-stage accretion that is marked by partial equilibration of large impactors. The second, possibly more intuitive mode, requires that Earth accreted - at least initially - from volatile poor material preferentially depleted in S relative to Sn, Zn, and Cu. From a chemical standpoint, this source material is most similar to type I chondrule rich (and S poor) materials (Hewins and Herzberg, 1996; Mahan et al., 2017; Amsellem et al., 2017), such as the metal-bearing carbonaceous chondrites.

Understanding Student Cognition about Complex Earth System Processes Related to Climate Change

Science.gov (United States)

McNeal, K. S.; Libarkin, J.; Ledley, T. S.; Dutta, S.; Templeton, M. C.; Geroux, J.; Blakeney, G. A.

2011-12-01

The Earth's climate system includes complex behavior and interconnections with other Earth spheres that present challenges to student learning. To better understand these unique challenges, we have conducted experiments with high-school and introductory level college students to determine how information pertaining to the connections between the Earth's atmospheric system and the other Earth spheres (e.g., hydrosphere and cryosphere) are processed. Specifically, we include psychomotor tests (e.g., eye-tracking) and open-ended questionnaires in this research study, where participants were provided scientific images of the Earth (e.g., global precipitation and ocean and atmospheric currents), eye-tracked, and asked to provide causal or relational explanations about the viewed images. In addition, the students engaged in on-line modules (http://serc.carleton.edu/eslabs/climate/index.html) focused on Earth system science as training activities to address potential cognitive barriers. The developed modules included interactive media, hands-on lessons, links to outside resources, and formative assessment questions to promote a supportive and data-rich learning environment. Student eye movements were tracked during engagement with the materials to determine the role of perception and attention on understanding. Students also completed a conceptual questionnaire pre-post to determine if these on-line curriculum materials assisted in their development of connections between Earth's atmospheric system and the other Earth systems. The pre-post results of students' thinking about climate change concepts, as well as eye-tracking results, will be presented.

Rare earths and actinides

International Nuclear Information System (INIS)

Coqblin, B.

1982-01-01

This paper reviews the different properties of rare-earths and actinides, either as pure metals or as in alloys or compounds. Three different cases are considered: (i) First, in the case of 'normal' rare-earths which are characterized by a valence of 3, we discuss essentially the magnetic ordering, the coexistence between superconductivity and magnetism and the properties of amorphous rare-earth systems. (ii) Second, in the case of 'anomalous' rare-earths, we distinguish between either 'intermediate-valence' systems or 'Kondo' systems. Special emphasis is given to the problems of the 'Kondo lattice' (for compounds such as CeAl 2 ,CeAl 3 or CeB 6 ) or the 'Anderson lattice' (for compounds such as TmSe). The problem of neutron diffraction in these systems is also discussed. (iii) Third, in the case of actinides, we can separate between the d-f hybridized and almost magnetic metals at the beginning of the series and the rare-earth like the metals after americium. (orig.)

The effect of environmental conditions on the stability of heavy metal-filter material complex as assessed by the leaching of adsorbed metal ions

Energy Technology Data Exchange (ETDEWEB)

Khokhotva, Oleksandr, E-mail: khokhotva@bigmir.net [School of Sustainable Development of Society and Technology, Maelardalen University, Box 883, SE-721 23, Vaesteras (Sweden); Waara, Sylvia, E-mail: sylvia.waara@hh.se [School of Sustainable Development of Society and Technology, Maelardalen University, Box 883, SE-721 23, Vaesteras (Sweden)

2011-06-15

In this study the influence of environmental conditions, most likely prevailing in filter beds used for intermittently discharged pollutant streams such as landfill leachate and storm water, on the stability of the heavy metal-filter complex was investigated for 2 filter materials; non-treated and urea treated pine bark, using leaching experiments. The metal-filter complex stability was higher for urea treated than for non-treated pine bark and dependent on the metal adsorbed. The type of environmental condition applied was of less importance for the extent of leaching. - Highlights: > Metal-pine bark complex stability under changing environmental conditions is studied. > Metal leaching from non-treated bark is much higher than from urea-treated bark. > No significant influence of changing environmental conditions on the leaching extent. > Metal leaching from wet bark samples exposed to freezing is somewhat higher.> Zn leaching is the highest and Cu leaching is the lowest for both bark samples. - The study assess the metal-filter material complex stability when metal removal using filter material is used in locations with fluctuating environmental conditions.

The effect of environmental conditions on the stability of heavy metal-filter material complex as assessed by the leaching of adsorbed metal ions

International Nuclear Information System (INIS)

Khokhotva, Oleksandr; Waara, Sylvia

2011-01-01

In this study the influence of environmental conditions, most likely prevailing in filter beds used for intermittently discharged pollutant streams such as landfill leachate and storm water, on the stability of the heavy metal-filter complex was investigated for 2 filter materials; non-treated and urea treated pine bark, using leaching experiments. The metal-filter complex stability was higher for urea treated than for non-treated pine bark and dependent on the metal adsorbed. The type of environmental condition applied was of less importance for the extent of leaching. - Highlights: → Metal-pine bark complex stability under changing environmental conditions is studied. → Metal leaching from non-treated bark is much higher than from urea-treated bark. → No significant influence of changing environmental conditions on the leaching extent. → Metal leaching from wet bark samples exposed to freezing is somewhat higher.→ Zn leaching is the highest and Cu leaching is the lowest for both bark samples. - The study assess the metal-filter material complex stability when metal removal using filter material is used in locations with fluctuating environmental conditions.

Insights into aquatic toxicities of the antibiotics oxytetracycline and ciprofloxacin in the presence of metal: Complexation versus mixture

Energy Technology Data Exchange (ETDEWEB)

Yu, Zhang [Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China); Cai Xiyun, E-mail: xiyuncai@dlut.edu.cn [Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China); Xianming, Lang [Liaoning Academy of Environmental Sciences, Shenyang 110031 (China); Xianliang, Qiao; Xuehua, Li; Jingwen, Chen [Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China)

2012-07-15

Co-contamination of ligand-like antibiotics (e.g., tetracyclines and quinolones) and heavy metals prevails in the environment, and thus the complexation between them is involved in environmental risks of antibiotics. To understand toxicological significance of the complex, effects of metal coordination on antibiotics' toxicity were investigated. The complexation of two antibiotics, oxytetracycline and ciprofloxacin, with three heavy metals, copper, zinc, and cadmium, was verified by spectroscopic techniques. The antibiotics bound metals via multiple coordination sites and rendered a mixture of various complexation speciations. Toxicity analysis indicated that metal coordination did modify the toxicity of the antibiotics and that antibiotic, metal, and their complex acted primarily as concentration addition. Comparison of EC{sub 50} values revealed that the complex commonly was highest toxic and predominately correlated in toxicity to the mixture. Finally, environmental scenario analysis demonstrated that ignoring complexation would improperly classify environmental risks of the antibiotics. - Highlights: Black-Right-Pointing-Pointer The complex of antibiotic with metal is a mixture of various complexation modes. Black-Right-Pointing-Pointer Antibiotic and metal act as various combined interactions when their complexation is ignored. Black-Right-Pointing-Pointer Antibiotic, metal, and their complex act as concentration addition interaction. Black-Right-Pointing-Pointer Complex commonly is the highest toxicant. Black-Right-Pointing-Pointer Neglecting complexation renders improper classification of risks for antibiotics. - Antibiotic, heavy metal and their complex act primarily as concentration addition interaction and the complex commonly is highest toxic.

Application of NASA management approach to solve complex problems on earth

Science.gov (United States)

Potate, J. S.

1972-01-01

The application of NASA management approach to solving complex problems on earth is discussed. The management of the Apollo program is presented as an example of effective management techniques. Four key elements of effective management are analyzed. Photographs of the Cape Kennedy launch sites and supporting equipment are included to support the discussions.

Transition metal complexes with oxygen donor ligands: a synthesis, spectral, thermal and antimicrobial study

Directory of Open Access Journals (Sweden)

VAIBHAV N. PATANGE

2008-10-01

Full Text Available Transition metal complexes of chalcones derived from the conden¬sation of 3-acetyl-6-methyl-2H-pyran-2,4(3H-dione (dehydroacetic acid and p-methoxybenzaldehyde (HL1 or p-nitrobenzaldehyde (HL2 were synthesized and characterized by elemental analysis, conductometry, thermal analysis, magnetic measurements, IR, 1H-NMR, UV–Vis spectroscopy and a microbial study. From the analytical and thermal data, the stoichiometry of the complexes was found to be 1:2 (metal:ligand. The molar conductance data revealed that all the metal chelates were non-electrolytes. The thermal stability of the complexes was studied by thermogravimetry and the decomposition schemes of the complexes are given. The ligands and their metal complexes were screened for antibacterial activity against Staphylococcus aureus and Escherichia coli, and fungicidal activity against Aspergillus flavus, Curvularia lunata and Penicillium notatum.

Labile rhizosphere soil solution fraction for prediction of bioavailability of heavy metals and rare earth elements to plants.

Science.gov (United States)

Shan, Xiao-Quan; Wang, Zhongwen; Wang, Weisheng; Zhang, Shuzhen; Wen, Bei

2003-02-01

A labile rhizosphere soil solution fraction has been recommended to predict the bioavailability of heavy metals and rare earth elements to plants. This method used moist rhizosphere soil in combination with a mixture of 0.01 mol L(-1) of low-molecular-weight organic acids (LMWOAs) as extractant. The extracted soil solutions were fractionated into two colloidal fractions of soil solution fraction, F(lrss). For the soil solutions extracted with a mixture of LMWOAs the concentrations of heavy metals and rare earth elements in F(2) and F(3) were quite similar. However, the mean concentrations of Cr, Ni, Zn, Cu, Pb, Cd, La, Ce, Pr, and Nd in F(lrss) accounted for 79.9%, 91.3%, 90.8%, 60.1%, 77.5%, 75.3%, 81.2%, 77.2%, 80.3%, and 79.5%, respectively, of their concentrations in F(2). In contrast, there were no differences in the extractable metal concentrations between the three fractions while the first step of the method recommended by the European Community of Reference (BCR), where 0.1 mol L(-1) acetic acid was used as an extractant. The single correlation analysis was made between metal concentrations in the different fractions of soil solutions and their concentrations in wheat. If the first step of BCR method was used there was no good correlation between heavy metals in soil pools and that in wheat shoots and roots. When LMWAOs were used a good correlation was obtained between the concentrations of heavy metals in soil pools and that in wheat roots, which followed a general order of r(1 kD, LMWOAs) >r(0.2 microm, LMWOAs) approximately r(0.45 microm, LMWOAs). In the case of rare earth elements the good correlation was obtained for both the wheat roots and shoots. Generally, the correlation coefficients obtained by LMWAOs were better than that obtained by the first step of BCR method. Therefore, LMWAOs and F(lrss) were strongly recommended to predict the bioavailability of metals in soil pools to plants.

Metal-ion complexes of functionalised 1,10-Phenanthrolines as hydrolytic synzymes

NARCIS (Netherlands)

Weijnen, J.G.J.

1993-01-01

In this thesis metal-ion complexes of functionalised 1,10-phenanthroline derivatives have been studied as model systems for hydrolytic metallo-enzymes. Amphiphilic metallo- complexes incorporated into micelles or vesicles and water-soluble complexes in pure aqueous buffer solutions, have

Quantitative Interpretation of Multifrequency Multimode EPR Spectra of Metal Containing Proteins, Enzymes, and Biomimetic Complexes.

Science.gov (United States)

Petasis, Doros T; Hendrich, Michael P

2015-01-01

Electron paramagnetic resonance (EPR) spectroscopy has long been a primary method for characterization of paramagnetic centers in materials and biological complexes. Transition metals in biological complexes have valence d-orbitals that largely define the chemistry of the metal centers. EPR spectra are distinctive for metal type, oxidation state, protein environment, substrates, and inhibitors. The study of many metal centers in proteins, enzymes, and biomimetic complexes has led to the development of a systematic methodology for quantitative interpretation of EPR spectra from a wide array of metal containing complexes. The methodology is now contained in the computer program SpinCount. SpinCount allows simulation of EPR spectra from any sample containing multiple species composed of one or two metals in any spin state. The simulations are quantitative, thus allowing determination of all species concentrations in a sample directly from spectra. This chapter will focus on applications to transition metals in biological systems using EPR spectra from multiple microwave frequencies and modes. © 2015 Elsevier Inc. All rights reserved.

Facile synthesis of highly biocompatible folic acid-functionalised SiO2 nanoparticles encapsulating rare-earth metal complexes, and their application in targeted drug delivery.

Science.gov (United States)

Xu, Xiuling; Hu, Fan; Shuai, Qi

2017-11-14

Mesoporous silica core-shell nanospheres encapsulating a rare-earth metal complex (RC) were first synthesised through a facile W/O (water in oil) inverse microemulsion method. In order to achieve targeted complex delivery, folic acid (FA) was used as the targeting component due to its high affinity for over-expressed folate receptors (FRs) in cancer cells. The RC 2 @SiO 2 -FA nanospheres were characterised via ultraviolet-visible light absorption spectroscopy (UV-vis spectroscopy), dynamic light scattering (DLS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A microwave method was used to synthesise five RC cores based on 4-chlorophenoxyacetic acid, and their crystal structures were further confirmed using X-ray diffraction. The five RC cores have the following chemical formulae: [Er 2 (p-CPA) 6 (H 2 O) 6 ] RC 1 , [Ho 2 (p-CPA) 6 (H 2 O) 6 ] RC 2 , [Sm(p-CPA) 3 (H 2 O)] RC 3 , [Pr(p-CPA) 3 (H 2 O)]·3H 2 O RC 4 and [Ce(p-CPA) 3 (H 2 O) 2 ]·2H 2 O RC 5 . The carboxyl groups showed two kinds of coordination modes, namely μ 2 -η 1 :η 1 and μ 2 -η 1 :η 2 , among RC 1 -RC 5 . The flexible -OCH 2 COO- spacer group, which can undergo rotation of its C-O and C-C bonds, offered great potential for structural diversity. In vivo experiments revealed that the nanospheres exhibited no obvious cytotoxicity on HepG2 cells and 293 T cells, even at concentrations of up to 80 μg mL -1 . Nevertheless, all of the RC cores showed a certain degree of anti-tumour efficacy; in particular, RC 2 showed the strongest cytotoxicity against HepG2 cells. Interestingly, the cytotoxicity of all of the RC 2 @SiO 2 -FA nanospheres was higher than that of lone RC 2 . These types of FA-targeted mesoporous silica nanocarriers can be used for the delivery of anti-tumour RC, and provide a basis for the further study of affordable non-platinum-based complexes.

Interaction of Cr (III), Ni (II), Pb (II) with DTPA complexes of essential metal ions

International Nuclear Information System (INIS)

Gulzar, S.; Zahida; Maqsood, T.; Naqvi, R.R.

2002-01-01

With the increase of anthropogenic activities in the environment, heavy metal toxicity (Chromium, Nickel and Lead) is more common now. DTPA (diethylene triamine pentaacetic acid) a polyamino carboxylic acid is widely used to form hydrophilic and stable complexes with most of the metal ions. In this spectrophotometric study, concentration of Cr(III), Ni(II) and Pb(II) (toxic metal ions) exchanged with Fe(III), Zn(II) and Ca(II) from their DTPA complexes were estimated at pH 4,7 and 9. Concentration of added metal was varied from 1-4 times to that of complexed metal. (author)

Polyoxometalate electrocatalysts based on earth-abundant metals for efficient water oxidation in acidic media

Science.gov (United States)

Blasco-Ahicart, Marta; Soriano-López, Joaquín; Carbó, Jorge J.; Poblet, Josep M.; Galan-Mascaros, J. R.

2018-01-01

Water splitting is a promising approach to the efficient and cost-effective production of renewable fuels, but water oxidation remains a bottleneck in its technological development because it largely relies on noble-metal catalysts. Although inexpensive transition-metal oxides are competitive water oxidation catalysts in alkaline media, they cannot compete with noble metals in acidic media, in which hydrogen production is easier and faster. Here, we report a water oxidation catalyst based on earth-abundant metals that performs well in acidic conditions. Specifically, we report the enhanced catalytic activity of insoluble salts of polyoxometalates with caesium or barium counter-cations for oxygen evolution. In particular, the barium salt of a cobalt-phosphotungstate polyanion outperforms the state-of-the-art IrO2 catalyst even at pH < 1, with an overpotential of 189 mV at 1 mA cm-2. In addition, we find that a carbon-paste conducting support with a hydrocarbon binder can improve the stability of metal-oxide catalysts in acidic media by providing a hydrophobic environment.

The estimation of H-bond and metal ion-ligand interaction energies in the G-Quadruplex ⋯ Mn+ complexes

Science.gov (United States)

Mostafavi, Najmeh; Ebrahimi, Ali

2018-06-01

In order to characterize various interactions in the G-quadruplex ⋯ Mn+ (G-Q ⋯ Mn+) complexes, the individual H-bond (EHB) and metal ion-ligand interaction (EMO) energies have been estimated using the electron charge densities (ρs) calculated at the X ⋯ H (X = N and O) and Mn+ ⋯ O (Mn+ is an alkaline, alkaline earth and transition metal ion) bond critical points (BCPs) obtained from the atoms in molecules (AIM) analysis. The estimated values of EMO and EHB were evaluated using the structural parameters, results of natural bond orbital analysis (NBO), aromaticity indexes and atomic charges. The EMO value increase with the ratio of ionic charge to radius, e/r, where a linear correlation is observed between EMO and e/r (R = 0.97). Meaningful relationships are also observed between EMO and indexes used for aromaticity estimation. The ENH value is higher than EOH in the complexes; this is in complete agreement with the trend of N⋯Hsbnd N and O⋯Hsbnd N angles, the E (2) value of nN → σ*NH and nO → σ*NH interactions and the difference between the natural charges on the H-bonded atom and the hydrogen atom of guanine (Δq). In general, the O1MO2 angle becomes closer to 109.5° with the increase in EMO and decrease in EHB in the presence of metal ion.

Separation of strontium ions from other alkaline earth metal ions using masking reagent

International Nuclear Information System (INIS)

Komatsu, Y.

1996-01-01

Cs + and Sr 2+ have been well known as serious elements in high level radioactive waste. Separation of Cs + has already been successful when using an ion-exchange method from solution in the presence of other alkali metal ions. The separation of Sr 2+ is, however, not so easy by any known separation method such as solvent-extraction and ion-exchange methods. This is because Sr 2+ is in the middle of the selectivity series, which is Mg 2+ > Ca 2+ > Sr 2+ > Ba 2+ for the solvent-extraction method and Ba 2+ > Sr 2+ > Ca 2+ > Mg 2+ for the ion- exchange method. In the present study, separation of strontium from other alkaline earth metal ions was studied by a combined use of three types of separation methods at 298 K: the solvent-extraction method was applied for the first separation, in which thenoyltrifluoroacetone (TTA, extractant) and trioctylphosphine oxide ( TOPO, adduct forming ligand) were used for the organic phase of the system. The separation factors for each combination of four alkaline earth metal ions were determined by the values of the distribution ratio. The Mg 2+ was well separated from Sr 2+ by the TTA-TOPO system. However, the separation of the combinations of Ca 2+ -Sr 2+ and Sr 2+ -Ba 2+ was not complete by the above solvent-extraction system. The second separation method, an ion-exchange method was applied using dihydrogen tetratitanate hydrate fibers (H 2 Ti 4 O 9 nH 2 O) as an ion exchanger to separate Sr 2+ and Ba 2+ . The separation factors for each combination of four alkaline earth metal ions were calculated by the values of the distribution coefficients. Ba 2+ was well separated from Sr 2+ by the ion-exchange method. To separate Ca 2+ and Sr 2+ , however, a modified solvent-extraction method was finally used in which H 2 Ti 4 O 9 nH 2 O was used as a masking reagent of Sr 2+ . After the dihydrogen tetratitanate hydrate fibers were contacted with the aqueous solution containing Ca 2+ and Sr 2+ , the organic solution containing TTA and TOPO

Processing of Phosphorus Slag with Recovery of Rare Earth Metals and Obtaining Silicon Containing Cake

Science.gov (United States)

Karshigina, Zaure; Abisheva, Zinesh; Bochevskaya, Yelena; Akcil, Ata; Sharipova, Aynash; Sargelova, Elmira

2016-10-01

The present research is devoted to the processing of slag generating during the yellow phosphorus production. In this paper are presented studies on leaching of phosphorus production slag by nitric acid with recovery of rare earth metals (REMs) into solution. REMs recovery into the solution achieved 98 % during the leaching process with using 7.5 mol/L of HNO3, liquid-to-solid ratio is 2.6:1, temperature is 60°C, process duration is 1 hour and stirrer speed is 500 rpm. Behaviour during the leaching of associated components such as calcium, aluminium, and iron was studied. After the leaching cake contains ∼⃒75-85 % of SiO2 and it might be useful for obtaining of precipitated silicon dioxide. With the purpose of separation from the impurities, recovery and concentrating of REMs, the obtained solution after leaching was subjected to extraction processing methods. The influence of ratio of organic and aqueous phases (O: A) on the extraction of rare earth metals by tributyl phosphate (TBP) with concentrations from 20 up to 100 % was studied. The REMs extraction with increasing TBP concentration under changes O:A ratio from 1:20 down to 1:1 into the organic phase from the solutions after nitric acid leaching increased from 22.2 up to 99.3%. The duration effect of REMs extraction process was studied by tributyl phosphate. It is revealed that with increasing of duration of the extraction process from 10 to 30 minutes REMs recovery into the organic phase almost did not changed. The behaviour of iron in the extraction process by TBP was studied. It was found that such accompanying components as calcium and aluminium by tributyl phosphate didn't extracted. To construct isotherm of REMs extraction of by tributyl phosphate was used variable volume method. It was calculated three-step extraction is needed for REMs recovery from the solutions after nitric acid leaching of phosphorus production slag. The process of the three-steps counter current extraction of rare earth

Metal complex catalysis in the synthesis of organoaluminium compounds

International Nuclear Information System (INIS)

Dzhemilev, Usein M; Ibragimov, Askhat G

2000-01-01

The published data on the synthesis of organoaluminium compounds involving metal complex catalysts are generalised and systematised. Hydro-, carbo- and cycloalumination reactions of alkenes, conjugated dienes and alkynes catalysed by Ti and Zr complexes are considered in detail. The use of organoaluminium reagents in organic synthesis and novel reactions involving these compounds are discussed. The bibliography includes 240 references.

Quantification of trace metals in water using complexation and filter concentration.

Science.gov (United States)

Dolgin, Bella; Bulatov, Valery; Japarov, Julia; Elish, Eyal; Edri, Elad; Schechter, Israel

2010-06-15

Various metals undergo complexation with organic reagents, resulting in colored products. In practice, their molar absorptivities allow for quantification in the ppm range. However, a proper pre-concentration of the colored complex on paper filter lowers the quantification limit to the low ppb range. In this study, several pre-concentration techniques have been examined and compared: filtering the already complexed mixture, complexation on filter, and dipping of dye-covered filter in solution. The best quantification has been based on the ratio of filter reflectance at a certain wavelength to that at zero metal concentration. The studied complex formations (Ni ions with TAN and Cd ions with PAN) involve production of nanoparticle suspensions, which are associated with complicated kinetics. The kinetics of the complexation of Ni ions with TAN has been investigated and optimum timing could be found. Kinetic optimization in regard to some interferences has also been suggested.

Metathesis synthesis and characterization of complex metal fluoride ...

Indian Academy of Sciences (India)

Administrator

V MANIVANNAN*, P PARHI and JONATHAN W KRAMER. Department of Mechanical Engineering, Campus Delivery 1374, Colorado State University, Fort Collins,. CO 80523, USA. MS received 30 April 2008. Abstract. Metathesis synthesis of complex metal fluorides using mechanochemical activation has been reported.

Influence of alkali metal oxides and alkaline earth metal oxides on the mitigation of stress corrosion cracking in CANDU fuel sheathing

Energy Technology Data Exchange (ETDEWEB)

Metzler, J.; Ferrier, G.A.; Farahani, M.; Chan, P.K.; Corcoran, E.C., E-mail: Joseph.Metzler@rmc.ca [Royal Military College of Canada, Kingston, ON (Canada)

2015-07-01

Stress corrosion cracking (SCC)can cause failures of CANDU Zircaloy-4 fuel sheathing. The process occurs when a corrosive element (i.e.,iodine) interacts with a susceptible material that is under sufficient strain at a high temperature. Currently, there is an ongoing effort to improve SCC mitigation strategies for future iterations of CANDU reactors. A potential mechanism for SCC mitigation involves utilizing alkali metal oxides and alkaline earth metal oxides that will sequester corrosive iodine while actively repairing a protective oxide layer on the sheath. SCC tests performed with sodium oxide (Na{sub 2}O) and calcium oxide (CaO) have shown to decrease significantly the sheath degradation. (author)

NMR study of rare earth and actinide complexes

International Nuclear Information System (INIS)

Villardi de Montlaur de, G.C.

1978-01-01

Proton magnetic resonance studies of lanthanide shift reagents with olefin-transition metal complexes, monoamines and diamines as substrates are described. Shift reagents for olefins are reported: Lnsup(III)(fod) 3 can induce substantial shifts in the nmr spectra of a variety of olefins when silver 1-heptafluororobutyrate is used to complex the olefin. The preparation, properties and efficiency of such systems are described. Configurational aspects and exchange processes of Lnsup(III)(fod) 3 complexes with secondary and tertiary monoamines are analysed by means of dynamic nmr. Factors influencing the stability and the stoichiometry of these complexes and various processes such as nitrogen inversion and ligand exchange are discussed. At low temperature, ring inversion can be slow on an nmr time-scale for Lnsup(III)(fod) 3 -diamino chelates. Barriers to ring inversion in substituted ethylenediamines and propanediamines are obtained. Steric factors appear to play an important role in the stability and kinetics of these bidentate species. The synthesis of uranium-IV crown-ether and cryptate complexes is described. A conformational study of these compounds show evidence of an insertion of the paramagnetic cation as witnessed by the large induced shifts observed. The insertion of uranium in the macrocyclic ligand of a UCl 4 -dicyclohexyl-18-crown-6 complex is confirmed by an X-ray structural determination [fr

Soil Heavy Metal Concentrations in Green Space of Mobarake Steel Complex

Directory of Open Access Journals (Sweden)

vahid Moradinasab

2017-01-01

Full Text Available Introduction: Water shortage in arid and semiarid regions of the world is a cause of serious concerns. The severe water scarcity urges the reuse of treated wastewater effluent and marginal water as a resource for irrigation. Mobarake Steel Complex has been using treated industrial wastewater for drip-irrigation of trees in about 1350 ha of its green space. However, wastewater may contain some amounts of toxic heavy metals, which create problems. Excessive accumulation of heavy metals in agricultural soils through wastewater irrigation may not only result in soil contamination, but also affect food quality and safety. Improper irrigation management, however, can lead to the loss of soil quality through such processes as contamination and salination. Soil quality implies its capacity to sustain biological productivity, maintain environmental quality, and enhance plants, human and animal health. Soil quality assessment is a tool that helps managers to evaluate short-term soil problems and appropriate management strategies for maintaining soil quality in the long time. Mobarakeh Steel Complex has been using treated wastewater for irrigation of green space to combat water shortage and prevent environmental pollution. This study was performed to assess the impact of short- middle, and long-term wastewater irrigation on soil heavy metal concentration in green space of Mobarake Steel complex. Materials and Methods: The impacts of wastewater irrigation on bioavailable and total heavy metal concentrations in the soils irrigated with treated wastewater for 2, 6 and 18 years as compared to those in soils irrigated with groundwater and un-irrigated soils. Soils were sampled from the wet bulb produced by under-tree sprinklers in three depths (0-20, 20-40 and 40-60 cm. Soil samples were air-dried, and crushed to pass through a 2-mm sieve. Plant-available metal concentrations were extracted from the soil with diethylenetriaminepentaacetic acid-CaCl2

Density functional theory study on Herzberg-Teller contribution in Raman scattering from 4-aminothiophenol-metal complex and metal-4-aminothiophenol-metal junction

Science.gov (United States)

Liu, Shasha; Zhao, Xiuming; Li, Yuanzuo; Zhao, Xiaohong; Chen, Maodu

2009-06-01

Density functional theory (DFT) and time-dependent DFT calculations have been performed to investigate the Raman scattering spectra of metal-molecule complex and metal-molecule-metal junction architectures interconnected with 4-aminothiophenol (PATP) molecule. The simulated profiles of normal Raman scattering (NRS) spectra for the two complexes (Ag2-PATP and PATP-Au2) and the two junctions (Ag2-PATP-Au2 and Au2-PATP-Ag2) are similar to each other, but exhibit obviously different Raman intensities. Due to the lager static polarizabilities of the two junctions, which directly influence the ground state chemical enhancement in NRS spectra, the calculated normal Raman intensities of them are stronger than those of two complexes by the factor of 102. We calculate preresonance Raman scattering (RRS) spectra with incident light at 1064 nm, which is much lower than the S1 electronic transition energy of complexes and junctions. Ag2-PATP-Au2 and Au2-PATP-Ag2 junctions yield higher Raman intensities than those of Ag2-PATP and PATP-Au2 complexes, especially for b2 modes. This effect is mainly attributed to charge transfer (CT) between the metal gap and the PAPT molecule which results in the occurrence of CT resonance enhancement. The calculated pre-RRS spectra strongly depend on the electronic transition state produced by new structures. With excitation at 514.5 nm, the calculated pre-RRS spectra of two complexes and two junctions are stronger than those of with excitation at 1064 nm. A charge difference densities methodology has been used to visually describe chemical enhancement mechanism of RRS spectrum. This methodology aims at visualizing intermolecular CT which provides direct evidence of the Herzberg-Teller mechanism.

Sintered cobalt-rare earth intermetallic product

International Nuclear Information System (INIS)

Benz, M.C.

1975-01-01

A process is described for preparing novel sintered cobalt--rare earth intermetallic products which can be magnetized to form permanent magnets having stable improved magnetic properties. A cobalt--rare earth metal alloy is formed having a composition which at sintering temperature falls outside the composition covered by the single Co 5 R intermetallic phase on the rare earth richer side. The alloy contains a major amount of the Co 5 R intermetallic phase and a second solid CoR phase which is richer in rare earth metal content than the Co 5 R phase. The specific cobalt and rare earth metal content of the alloy is substantially the same as that desired in the sintered product. The alloy, in particulate form, is pressed into compacts and sintered to the desired density. The sintered product is comprised of a major amount of the Co 5 R solid intermetallic phase and up to about 35 percent of the product of the second solid CoR intermetallic phase which is richer in rare earth metal content than the Co 5 R phase

Thermodynamic studies on the interaction between some amino acids with some rare earth metal ions in aqueous solutions

International Nuclear Information System (INIS)

Mohamed, AbdAllah A.; Bakr, Moustafa F.; Abd El-Fattah, Khaled A.

2003-01-01

The interactions between the amino acids (glycine and L-threonine) with some rare earth metal ions (Pr 3+ , Nd 3+ , Eu 3+ , Gd 3+ , Dy 3+ , Ho 3+ and Yb 3+ ) were studied at a wide range from ionic strengths (0.07-0.32 M KNO 3 ) and temperatures (25-45 deg. C) in aqueous solutions by using Bjerrum potentiometric method. The stoichiometric and thermodynamic stability constants were calculated as well as the standard thermodynamic parameters (ΔG deg., ΔH deg. and ΔS deg. ) for all possible reactions that occur. The degree of formation (n-bar) for all studied systems was determined and discussed. The thermodynamic parameters differences (ΔΔG deg., ΔΔH deg. and ΔΔS deg. ) were calculated and discussed to determine the factors which control these complexation processes from the thermodynamic point of view

Chemical bonding of hydrogen molecules to transition metal complexes

International Nuclear Information System (INIS)

Kubas, G.J.

1990-01-01

The complex W(CO) 3 (PR 3 ) 2 (H 2 ) (CO = carbonyl; PR 3 = organophosphine) was prepared and was found to be a stable crystalline solid under ambient conditions from which the hydrogen can be reversibly removed in vacuum or under an inert atmosphere. The weakly bonded H 2 exchanges easily with D 2 . This complex represents the first stable compound containing intermolecular interaction of a sigma-bond (H-H) with a metal. The primary interaction is reported to be donation of electron density from the H 2 bonding electron pair to a vacant metal d-orbital. A series of complexes of molybdenum of the type Mo(CO)(H 2 )(R 2 PCH 2 CH 2 PR 2 ) 2 were prepared by varying the organophosphine substitutent to demonstrate that it is possible to bond either dihydrogen or dihydride by adjusting the electron-donating properties of the co-ligands. Results of infrared and NMR spectroscopic studies are reported. 20 refs., 5 fig

Preparation of Palladium-Impregnated Ceria by Metal Complex Decomposition for Methane Steam Reforming Catalysis

Directory of Open Access Journals (Sweden)

Worawat Wattanathana

2017-01-01

Full Text Available Palladium-impregnated ceria materials were successfully prepared via an integrated procedure between a metal complex decomposition method and a microwave-assisted wetness impregnation. Firstly, ceria (CeO2 powders were synthesized by thermal decomposition of cerium(III complexes prepared by using cerium(III nitrate or cerium(III chloride as a metal source to form a metal complex precursor with triethanolamine or benzoxazine dimer as an organic ligand. Palladium(II nitrate was consequently introduced to the preformed ceria materials using wetness impregnation while applying microwave irradiation to assist dispersion of the dopant. The palladium-impregnated ceria materials were obtained by calcination under reduced atmosphere of 10% H2 in He stream at 700°C for 2 h. Characterization of the palladium-impregnated ceria materials reveals the influences of the metal complex precursors on the properties of the obtained materials. Interestingly, the palladium-impregnated ceria prepared from the cerium(III-benzoxazine dimer complex revealed significantly higher BET specific surface area and higher content of the more active Pdδ+ (δ > 2 species than the materials prepared from cerium(III-triethanolamine complexes. Consequently, it exhibited the most efficient catalytic activity in the methane steam reforming reaction. By optimization of the metal complex precursors, characteristics of the obtained palladium-impregnated ceria catalysts can be modified and hence influence the catalytic activity.

Complexes of 3.6 kDa Maltodextrin with Some Metals

Directory of Open Access Journals (Sweden)

Christopher H. Schilling

2004-06-01

Full Text Available Preparation of magnesium, lanthanum, and bismuth(III complexes of 3.6 kDa maltodextrin and some properties of the resulting materials are presented. The metal derivatives contain metals bound to the oxygen atoms of the hydroxyl groups of maltodextrin. Additionally, the metal atoms are coordinated to the hydroxyl groups of the D-glucose units of the macroligand. Such coordination stabilized the metal – oxygen bond against hydrolysis, even in boiling water. The presence of magnesium and lanthanum atoms increased the thermal stability of maltodextrin, whereas bismuth atoms decreased it.

The metallic ratios as limits of complex valued transformations

International Nuclear Information System (INIS)

Falcon, Sergio; Plaza, Angel

2009-01-01

We study the presence of the metallic ratios as limits of two complex valued transformations. These complex variable functions are introduced and related with the two geometric antecedents for each triangle in a particular triangle partition, the four-triangle longest-edge (4TLE) partition. In this way, the fractality of a geometric diagram for the classes of dissimilar generated triangles is also explained.

Universal viscosity growth in metallic melts at megabar pressures: the vitreous state of the Earth's inner core

International Nuclear Information System (INIS)

Brazhkin, Vadim V; Lyapin, A G

2000-01-01

Experimental data on and theoretical models for the viscosity of various types of liquids and melts under pressure are reviewed. Experimentally, the least studied melts are those of metals, whose viscosity is considered to be virtually constant along the melting curve. The authors' new approach to the viscosity of melts involves the measurement of the grain size in solidified samples. Measurements on liquid metals at pressures up to 10 GPa using this method show, contrary to the empirical approach, that the melt viscosity grows considerably along the melting curves. Based on the experimental data and on the critical analysis of current theories, a hypothesis of a universal viscosity behavior is introduced for liquids under pressure. Extrapolating the liquid iron results to the pressures and temperatures at the Earth's core reveals that the Earth's outer core is a very viscous melt with viscosity values ranging from 10 2 Pa s to 10 11 Pa s depending on the depth. The Earth's inner core is presumably an ultraviscous (>10 11 Pa s) glass-like liquid - in disagreement with the current idea of a crystalline inner core. The notion of the highly viscous interior of celestial bodies sheds light on many mysteries of planetary geophysics and astronomy. From the analysis of the pressure variation of the melting and glass-transition temperatures, an entirely new concept of a stable metallic vitreous state arises, calling for further experimental and theoretical study. (reviews of topical problems)

BIOASSAY STUDIES OF METAL(II) COMPLEXES OF 2,2'-(ETHANE ...

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diyldiimino)diacetic acid (EDDA) were prepared and characterized. Coordination complexes of the EDDA ... corresponding amines with alkyl halide to bear diammines of the same class with different substituents. ... Bioassay studies of metal(II) complexes of 2,2'-(ethane-1,2-diyldiimino)diacetic acid. Bull. Chem. Soc. Ethiop.

Emission Properties, Solubility, Thermodynamic Analysis and NMR Studies of Rare-Earth Complexes with Two Different Phosphine Oxides

Directory of Open Access Journals (Sweden)

Hiroki Iwanaga

2010-07-01

Full Text Available The paper proposes novel molecular designs for rare-earth complexes involving the introduction of two different phosphine oxide structures into one rare-earth ion. These designs are effective for improving solubility and emission intensity. Additionally, the complexes are indispensable for realizing high performances in LEDs and security media. The thermodynamic properties of Eu(III complexes are correlated with the solubility. Correlations between coordination structures and emission intensity were explained by NMR analysis. The luminous flux of red LED devices with Eu(III complexes is very high (20 mA, 870 m lumen. A new white LED has its largest spectra intensity in the red region and a human look much more vividly under this light.

Hyperfine structure of 2Σ molecules containing alkaline-earth-metal atoms

Science.gov (United States)

Aldegunde, Jesus; Hutson, Jeremy M.

2018-04-01

Ultracold molecules with both electron spin and an electric dipole moment offer new possibilities in quantum science. We use density-functional theory to calculate hyperfine coupling constants for a selection of molecules important in this area, including RbSr, LiYb, RbYb, CaF, and SrF. We find substantial hyperfine coupling constants for the fermionic isotopes of the alkaline-earth-metal and Yb atoms. We discuss the hyperfine level patterns and Zeeman splittings expected for these molecules. The results will be important both to experiments aimed at forming ultracold open-shell molecules and to their applications.

Two-photon Doppler cooling of alkaline-earth-metal and ytterbium atoms

International Nuclear Information System (INIS)

Magno, Wictor C.; Cavasso Filho, Reinaldo L.; Cruz, Flavio C.

2003-01-01

The possibility of laser cooling of alkaline-earth-metal atoms and ytterbium atoms using a two-photon transition is analyzed. We consider a 1 S 0 - 1 S 0 transition with excitation in near resonance with the 1 P 1 level. This greatly increases the two-photon transition rate, allowing an effective transfer of momentum. The experimental implementation of this technique is discussed and we show that for calcium, for example, two-photon cooling can be used to achieve a Doppler limit of 123 μK. The efficiency of this cooling scheme and the main loss mechanisms are analyzed

Preparation and properties of chitosan-metal complex: Some factors influencing the adsorption capacity for dyes in aqueous solution.

Science.gov (United States)

Rashid, Sadia; Shen, Chensi; Yang, Jing; Liu, Jianshe; Li, Jing

2018-04-01

Chitosan-metal complexes have been widely studied in wastewater treatment, but there are still various factors in complex preparation which are collectively responsible for improving the adsorption capacity need to be further studied. Thus, this study investigates the factors affecting the adsorption ability of chitosan-metal complex adsorbents, including various kinds of metal centers, different metal salts and crosslinking degree. The results show that the chitosan-Fe(III) complex prepared by sulfate salts exhibited the best adsorption efficiency (100%) for various dyes in very short time duration (10min), and its maximum adsorption capacity achieved 349.22mg/g. The anion of the metal salt which was used in preparation played an important role to enhance the adsorption ability of chitosan-metal complex. SO 4 2- ions not only had the effect of crosslinking through electrostatic interaction with amine group of chitosan polymer, but also could facilitate the chelation of metal ions with chitosan polymer during the synthesis process. Additionally, the pH sensitivity and the sensitivity of ionic environment for chitosan-metal complex were analyzed. We hope that these factors affecting the adsorption of the chitosan-metal complex can help not only in optimizing its use but also in designing new chitosan-metal based complexes. Copyright © 2017. Published by Elsevier B.V.

Synthesis, physico-chemical characterization and biological activity of 2-aminobenzimidazole complexes with different metal ions

Directory of Open Access Journals (Sweden)

Podunavac-Kuzmanović Sanja O.

2004-01-01

Full Text Available Complexes of 2-aminobenzimidazole (L with nitrates of cobalt(II nickel(II, copper (II, zinc(II and silver(I were synthesized. The molar ratio metal:ligand in the reaction of the complex formation was 1:2. It should be noticed, that the reaction of all the metal salts yielded bis(ligand complexes of the general formula M(L2(NO32 × nH2O (M=Co, Ni Cu, Zn or Ag; n=0, 1, 2 or 6. The complexes were characterized by elemental analysis of the metal, molar conductivity, magnetic susceptibility measurements and IR spectra. Co(II, Ni(II and Cu(II complexes behave as non-electrolytes, whilst Zn(II and Ag(I are 1:1 electrolytes. Cu(II complex has a square-planar stereochemistry, Ag(I complex is linear, whilst the Co(II, Ni(II and Zn(II complexes have a tetrahedral configuration. In all the complexes ligand is coordinated by participation of the pyridine nitrogen of the benzimidazole ring. The antimicrobial activity of the ligand and its complexes against Pseudomonas aeruginosa, Bacillus sp. Staphylococcus aureus and Saccharomyces cerevisiae was investigated. The effect of metal on the ligand antimicrobial activity is discussed.

Preparation and Characterization of Double Metal Cyanide Complex Catalysts

Directory of Open Access Journals (Sweden)

Weilin Guo

2003-01-01

Full Text Available A series of double metal cyanide (DMC complex catalysts were prepared in two different methods by using ß-cyclodextrin, PEG-1000 and Tween-60 as an additional complex ligands respectively. It was showed that a mixture of crystalline and amorphous DMC was synthesized by using traditional method in which the additional complex ligand was added after the precipitation of DMC. Amorphous and dispersed DMC with higher activity could be obtained when the additional complex ligand was added in the reactant solution before reaction. The effect of additional complex ligand and preparation method on the crystalline state and catalytic property of DMC were also investigated.

A detailed in vitro study of naproxen metal complexes in quest of ...

African Journals Online (AJOL)

Md. Sharif Hasan

2016-07-01

Jul 1, 2016 ... possibilities of using Naproxen metal complexes for different therapeutic ..... FTIR spectra, scanning electron microscopy and HPLC study of Naproxen metal ..... aminobenzoic acid and 2-aminophenol and their coordination.

Rare earths and rare earth alloys electrolytic preparation process and device for this process

International Nuclear Information System (INIS)

Seon, F.; Barthole, G.

1986-01-01

Electrolysis of a molten salt of rare earth or rare earth alloy for preparation of the metal or alloy is described. The molten salt bath comprises at least a rare earth chloride, at least an alkaline or alkaline earth chloride and at least an alkaline or alkaline earth fluoride [fr

Solution chemistry and separation of metal ions in leached solution

International Nuclear Information System (INIS)

Shibata, J.

1991-01-01

The method to presume a dissolved state of metal ions in an aqueous solution and the technology to separate and concentrate metal ions in a leached solution are described in this paper. It is very important for the separation of metal ions to know the dissolved state of metal ions. If we know the composition of an aqueous solution and the stability constants of metal-ligand complexes, we can calculate and estimate the concentration of each species in the solution. Then, we can decide the policy to separate and concentrate metal ions. There are several methods for separation and purification; hydroxide precipitation method, sulfide precipitation method, solvent extraction method and ion exchange resin method. Solvent extraction has been used in purification processes of copper refinery, uranium refinery, platinum metal refinery and rare earth metal refinery. Fundamental process of solvent extraction, a kind of commercial extractants, a way of determining a suitable extractant and an equipment are discussed. Finally, it will be emphasized how the separation of rare earths is improved in solvent extraction. (author) 21 figs., 8 tabs., 8 refs

Thiosemicarbazone complexes of the platinum metals. A story of ...

Indian Academy of Sciences (India)

Unknown

Thiosemicarbazone complexes; platinum metals; variable coordination; ... carbonylic carbon via one or two intervening atoms, D,N,S tricoordination usually takes .... modelling studies show that in this coordination mode, the phenyl ring of the.

Sub-chronic toxicological studies of transition metal complexes of ...

African Journals Online (AJOL)

Md. Sharif Hasan

2017-01-18

Jan 18, 2017 ... naproxen showed more side effects than metal complexes which ..... Fosslein E. Adverse effects of nonsteroidal anti-inflammatory drugs on the ... association increases the anti-inflammatory and analgesic activity of ibuprofen.

Complex Metal Hydrides for Hydrogen, Thermal and Electrochemical Energy Storage

DEFF Research Database (Denmark)

Moller, Kasper T.; Sheppard, Drew; Ravnsbaek, Dorthe B.

2017-01-01

Hydrogen has a very diverse chemistry and reacts with most other elements to form compounds, which have fascinating structures, compositions and properties. Complex metal hydrides are a rapidly expanding class of materials, approaching multi-functionality, in particular within the energy storage...... inspiration to solve the great challenge of our time: efficient conversion and large-scale storage of renewable energy....... field. This review illustrates that complex metal hydrides may store hydrogen in the solid state, act as novel battery materials, both as electrolytes and electrode materials, or store solar heat in a more efficient manner as compared to traditional heat storage materials. Furthermore, it is highlighted...

Studies on Oligomer Metal Complexes Derived from Bisamic Acid of Pyromellitic Dianhydride and 4-Bromoaniline.

Science.gov (United States)

Patel, Yogesh S

2014-01-01

Novel oligomer metal complexes (2a-f) of the ligand 2,5-bis((4-bromophenyl)carbamoyl) terephthalic acid (1) were prepared using transition metal salts and characterized by various spectroscopic techniques. The geometry of oligomer metal complexes was carried out by electronic spectral analysis and magnetic measurement studies. Polymeric properties have also been carried out. Ligand was synthesized using pyromellitic dianhydride and 4-bromoaniline. It was duly characterized. All novel synthesized compounds 1 and 2a-f were evaluated for their antibacterial and antifungal activity. The results showed significantly higher antibacterial and antifungal activity of oligomer metal complexes compared to the ligand.

Rare earth intermetallic compounds produced by a reduction-diffusion process

International Nuclear Information System (INIS)

Cech, R.E.

1975-01-01

A reduction-diffusion process is given for producing novel rare earth intermetallic compounds, such as cobalt--rare earth intermetallic compounds, especially compounds useful in preparing permanent magnets. A particulate mixture of rare earth metal halide, cobalt and calcium hydride is heated to effect reduction of the rare earth metal halide and to diffuse the resulting rare earth metal into the cobalt to form the intermetallic compound

Structural and thermal characterization of ternary complexes of piroxicam and alanine with transition metals: Uranyl binary and ternary complexes of piroxicam. Spectroscopic characterization and properties of metal complexes

Science.gov (United States)

Mohamed, Gehad G.

2005-12-01

Ternary Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and UO 2(II) complexes with piroxicam (Pir) drug (H 2L 1) and dl-alanine (Ala) (HL 2) and also the binary UO 2(II) complex with Pir were studied. The structures of the complexes were elucidated using elemental, IR, molar conductance, magnetic moment, diffused reflectance and thermal analyses. The UO 2(II) binary complex was isolated in 1:2 ratio with the formula [UO 2(H 2L) 2](NO 3) 2. The ternary complexes were isolated in 1:1:1 (M:H 2L 1:L 2) ratios. The solid complexes were isolated in the general formulae [M(H 2L)(L 2)(Cl) n(H 2O) m]· yH 2O (M = Fe(III) ( n = 2, m = 0, y = 1), Co(II) ( n = 1, m = 1, y = 2) and Ni(II) ( n = 1, m = 1, y = 0)); [M(H 2L)(L 2)](X) z· yH 2O (M = Cu(II) (X = AcO, z = 1, y = 0), Zn(II) (X = AcO, z = 1, y = 3) and UO 2(II) (X = NO 3, z = 1, y = 2)). Pir behaves as a neutral bidentate ligand coordinated to the metal ions via the pyridine-N and carbonyl-O groups, while Ala behaves as a uninegatively bidentate ligand coordinated to the metal ions via the deprotonated carboxylate-O and amino-N. The magnetic and reflectance spectral data show that the complexes have octahedral geometry except Cu(II) and Zn(II) complexes have tetrahedral structures. The thermal decomposition of the complexes was discussed in relation to structure, and the thermodynamic parameters of the decomposition stages were evaluated.

Study of solubility of akaline earth metals in liquid iron and in alloys on its base

International Nuclear Information System (INIS)

Ageev, Yu.A.; Archugov, S.A.

1985-01-01

Solubility of magnesium, calcium, strontium and barium in liquid iron and its alloys with aluminium, silicon, nickel, chromium and carbon at 1600 deg C has been measured. Interaction parameters taking account of the effect of added elements on alkaline earth metal solubility in liquid iron have been estimated

Some transition metal complexes derived from mono- and di-ethynyl perfluorobenzenes

NARCIS (Netherlands)

Armitt, D.J.; Bruce, M.I.; Gaudio, M.; Zaitseva, N.N.; Skelton, B.W.; White, A.H.; Le Guennic, B.; Halet, J.-F.; Fox, M.A.; Roberts, R.L.; Hartl, F.; Low, P.J.

2008-01-01

Transition metal alkynyl complexes containing perfluoroaryl groups have been prepared directly from trimethylsilyl-protected mono- and di-ethynyl perfluoroarenes by simple desilylation/metallation reaction sequences. Reactions between Me3SiC CC6F5 and RuCl(dppe)Cp'[Cp' = Cp, Cp*] in the presence of

Structural systematics of some metal complexes with 4,5 ...

Indian Academy of Sciences (India)

study reveals that each metal(II) centre in the four complexes adopts distorted octahedral geometry with MN6 ... potassium permanganate (E Merck, India), potassium. 717 ... The final reaction solu- ..... ble in water, methanol, acetonitrile, etc.

A review on versatile applications of transition metal complexes incorporating Schiff bases

Directory of Open Access Journals (Sweden)

Ahmed M. Abu-Dief

2015-06-01

Full Text Available Schiff bases and their complexes are versatile compounds synthesized from the condensation of an amino compound with carbonyl compounds and widely used for industrial purposes and also exhibit a broad range of biological activities including antifungal, antibacterial, antimalarial, antiproliferative, anti-inflammatory, antiviral, and antipyretic properties. Many Schiff base complexes show excellent catalytic activity in various reactions and in the presence of moisture. Over the past few years, there have been many reports on their applications in homogeneous and heterogeneous catalysis. The high thermal and moisture stabilities of many Schiff base complexes were useful attributes for their application as catalysts in reactions involving at high temperatures. The activity is usually increased by complexation therefore to understand the properties of both ligands and metal can lead to the synthesis of highly active compounds. The influence of certain metals on the biological activity of these compounds and their intrinsic chemical interest as multidentate ligands has prompted a considerable increase in the study of their coordination behaviour. Development of a new chemotherapeutic Schiff bases and their metal complexes is now attracting the attention of medicinal chemists. This review compiles examples of the most promising applied Schiff bases and their complexes in different areas.

Near-infrared dichroism of a mesogenic transition metal complex and its solubility in nematic hosts

International Nuclear Information System (INIS)

Marshall, K.L.; Jacobs, S.D.

1987-01-01

A transition metal complex possessing the nematic phase, bis (p-n-butylstyryl-1, 2-dithiolato) nickel, was synthesized and its optical properties and solubility in the nematic hosts K15 and MBBA were investigated. The metal complex displayed a high solubility in both host materials (up to 10% wt/wt) and a strong near-infrared absorption band centered at 860 nm. A blocking extinction of greater than OD = 3 was obtained with a 100 micron pathlength of a 0.5% wt/wt mixture of the nematic metal complex in K15, suggesting its usefulness for passive blocking of near infrared radiation. A 24 micron thick, homogeneously aligned guest-host cell containing a 1% wt/wt mixture of the metal complex in K15 possessed a contrast ratio of nearly 5:1 and a blocking extinction of OD = 3.5 at 860 nm, demonstrating for the first time the existence of near-infrared dichroism in this class of materials. The solubility and blocking extinction of the mesogenic metal complex in K15 was considerably superior to the non-mesogenic near ir laser dye bis(dimethylaminodithiobenzil) nickel in the same host. An interaction of the nematic metal complex in mixtures with MBBA which resulted in the creation of a new absorption band at 1050 nm was also observed. 21 refs., 9 figs

Enhanced Laser Cooling of Rare-Earth-Ion-Doped Glass Containing Nanometer-Sized Metallic Particles

International Nuclear Information System (INIS)

Jia Youhua; Zhong Biao; Yin Jianping

2009-01-01

The enhanced laser cooling performance of rare-earth-ions-doped glasses containing small particles is predicted. This is achieved by the enhancement of local field around rare earth ions, owing to the surface plasmon resonance of small metallic particles. The role of energy transfer between ions and the particle is theoretical discussed. Depending on the particle size and the ion emission quantum efficiency, the enhancement of the absorption and the fluorescence is predicted. Moreover, taking Yb 3+ -doped ZBLAN as example, the cooling power and heat-light converting efficiency are calculated. It is finally concluded that the absorption and the fluorescence are greatly enhanced in these composite materials, the cooling power is increased compared to the bulk material. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Theory of Rare-Earth Alloys

DEFF Research Database (Denmark)

Lindgård, Per-Anker

1977-01-01

A mean-field random alloy theory combined with a simple calculation of the exchange interaction J(c,Q) is shown to quantitatively account for the phase diagrams for alloys of rare-earth metals with Y, Lu, Sc, and other rare-earth metals. A concentration-dependent J(c,Q) explains the empirical 2...

Geology and rare earth (RE) metals in air Gegas area, South Bangka

International Nuclear Information System (INIS)

Bambang Soetopo

2013-01-01

Rare Earth (RE) is a valuable commodity both for industry and for the Nuclear Power Plant (NPP). In RE chemical bonds present in the phosphate (P) are the mineral monazite, xenotime, zircon minerals associated with cassiterite, magnetite, ilmenite, rutile, anatase, apatite, quartz and feldspar sand deposits are found in alluvial river or beach placer. RE deposits in monazite, zircon, xenotime in the Air Gegas of South Bangka area is an alluvial river that has the ease of exploration and mining. Geologically, monazite, xenotime and zircon minerals are from Klabat Granite aged Jurassic. The used method are the observation of geology, radioactivity measurement, sampling, laboratory analysis (microscopic and XRF). Results showed that the geology of the area Air Gegas of Tanjung Genting Formation consists of sandstone, clay (Early Triassic), Klabat Granite (Late Jurassic-Early Triassic) and Alluvial sediments (Quaternary). Alluvial monazite containing 0.071 to 3.574%, zircon from 0.172 to 10.376%, xenotime from 0.15 to 3.023% of the weight of MB from 10.73 to 168.072 grams. The presence of rare earth (RE) metals is derived from the mineral monazite, xenotime, zircon that was derived from granitic rocks of Klabat. Rare earth (RE) distributed in the eastern part of the study area which occupies the valley of the river. (author)

Spectrofluorimetric characterization and study for the determination of rare earth carbonate complexes

International Nuclear Information System (INIS)

Dantas, E.S.K.; Abrao, A.

1982-01-01

Some rare earths exhibit fluorescence in acid solution (HC1, H 2 SO 4 or HC10 4 ) when irradiated with ultraviolet radiation; however, analytical application of this property has not been proposed due to the lack of sensitivity resulted from the weakness of the fluorescence transitions. The rare earths are soluble in alkali carbonate solutions, forming anionic carbonate complexes (TR(CO 3 ) sup(n-) sub(x)); some of them have stronger absorption bands than those obtained in acid media. Using this property, the characterization and determination of the six rare earths which fluoresce in carbonate solution has been studied. The excitation and emission wavelengths are (in nm): Sm (406, 596); Eu (280,612); Gd (272,312); Tb (240,542); Dy (350, 576) and Tm (360, 450). Although Ce-III is highly fluorescent in acid media, when in carbonate solution it is easily oxidized to Ce-IV which does not fluoresce neither in acid nor in carbonate solutions. The other rare earths, although soluble in carbonate solution, do not fluoresce in this medium. A comparison is made, between the fluorescence of the fluorescing lanthanides, in acid and carbonate media. The precision and accuracy of this method, the detection limit of all rare earths studied and the mutual interference of some of them is also discussed. The method will be applied to the analytical control of the separation and purification of individual rare earths, now under development. (Author) [pt

Enhanced pinning in mixed rare earth-123 films

Science.gov (United States)

Driscoll, Judith L [Los Alamos, NM; Foltyn, Stephen R [Los Alamos, NM

2009-06-16

An superconductive article and method of forming such an article is disclosed, the article including a substrate and a layer of a rare earth barium cuprate film upon the substrate, the rare earth barium cuprate film including two or more rare earth metals capable of yielding a superconductive composition where ion size variance between the two or more rare earth metals is characterized as greater than zero and less than about 10.times.10.sup.-4, and the rare earth barium cuprate film including two or more rare earth metals is further characterized as having an enhanced critical current density in comparison to a standard YBa.sub.2Cu.sub.3O.sub.y composition under identical testing conditions.

Comparison of arsenic acid with phosphoric acid in the interaction with a water molecule and an alkali/alkaline-earth metal cation.

Science.gov (United States)

Park, Sung Woo; Kim, Chang Woo; Lee, Ji Hyun; Shim, Giwoong; Kim, Kwang S

2011-10-20

Recently, Wolfe-Simon has discovered a bacterium which is able to survive using arsenic(V) rather than phosphorus(V) in its DNA. Thus it is important to investigate some important structural and chemical similarities and dissimilarities between phosphate and arsenate. We compared the monohydrated structures and the alkali/alkaline-earth metal (Na(+), K(+), Mg(2+) and Ca(2+)) complexes of the arsenic acid/anions with those of the phosphoric acid/anions [i.e., H(m)PO(4)(-(3-m)) vs H(m)AsO(4)(-(3-m)) (m = 1-3)]. We carried out geometry optimization along with harmonic frequency calculations using ab initio calculations. Despite the increased van der Waals radius of As, the hydrated structures of both P and As systems show very close similarity (within 0.25 Å in the P/As···O(water) distance and within a few kJ/mol in binding energy) because of the increased induction energies by more polar arsenic acid/anons and slightly increased dispersion energy by a larger size of the As atom. In the metal complexes, the arsenic acid has a slightly larger binding distance (by 0.07-1.0 Å) and weaker binding energy because the As(V) ion has a slightly larger radius than the P(V) ion, and the electrostatic interaction is the dominating feature in these systems.

The treatment of complex airway diseases with inverted Y-shaped self-expandable metal stent

International Nuclear Information System (INIS)

Li Jianming; Jia Guangzhi

2011-01-01

Objective: To investigate the application and therapeutic effects of inverted Y-shaped self-expandable metal airway stent in treating complex airway diseases (stenosis or fistula). Methods: According to the distinctive anatomic structure and the pathological changes of complex airway stenosis or fistula, the inverted y-shaped self-expandable metal airway stent was designed. Under fluoroscopic monitoring, a total of 12 inverted Y-shaped self-expandable metal stents were implanted in 12 patients with complex airway diseases. Results: Stent placement in the trachea-bronchial tree was technically successful in all patients. After the operation, the symptom of dyspnea was immediately relieved and the bucking following food intake disappeared. The general physical condition and living quality were much improved in all patients. Conclusion: The use of inverted Y-shaped self-expandable metal airway stent for the management of complex airway stenosis involving the tracheal carina was a simple and safe procedure and it has satisfactory short-term clinical results. (authors)

Synthesis and optical properties of enantiomeric cinchonidine/cinchonine-terpyridine derivatives and their metal complexes

International Nuclear Information System (INIS)

Wang, Hui-Ting; Wu, Wen-Jie; Liu, Jiang; Chen, Meng; Qian, Dong-Jin; Zhang, Li; Liu, Minghua

2016-01-01

We report here the synthesis and spectroscopic properties of two enantiomeric chiral tridentate ligands (TPyCCD and TPyCCN) composed of terpyridine (TPy) and cinchonidine (CCD) or cinchonine (CCN) substituent, as well as their metal complexes with Zn 2+ , Fe 2+ , Eu 3+ , and Tb 3+ ions. For the pure ligands, the fluorescent emission intensity increased as their concentrations increased in the dilute solutions, but they decreased when the concentrations were greater than 6.9×10 −6 mol/l due to concentration quenching. No significant influence on ligand luminescence was observed for the Zn 2+ /Fe 2+ –TPyCCD and –TPyCCN metal complexes. Their lanthanide (Eu 3+ and Tb 3+ ) complexes displayed both ligand and lanthanide ion emissions, suggesting that the excited energy of both ligands could be transferred to the central Eu 3+ and Tb 3+ ions. Mirror-image circular dichroism spectra were recorded, with several signals centered at about 230, 250–270, 296, and 320 nm; the first ones corresponded to the chiral CCD and CCN substituents, while the latter ones corresponded to the TPy substituent and the metal–TPy (M-TPy) coordination units. It is suggested that the chirality of TPy and the metal complexes was induced by the coexisting chiral CCD and CCN substituents. In addition, due to formation of the metal complexes, the relative intensity of the chiral signals of M–TPy coordination units was enhanced at about 320 nm. - Highlights: • Cinchona alkaloid-terpyridine derivatives and metal complexes were prepared. • Cinchona alkaloid-terpyridine derivatives gave off luminescence at 362 nm. • Ligand excited energy could efficiently transferred to lanthanide ions. • Chirality of terpyridine and metal complexes was induced.

Tensorial analysis of the long-range interaction between metastable alkaline-earth-metal atoms

International Nuclear Information System (INIS)

Santra, Robin; Greene, Chris H.

2003-01-01

Alkaline-earth-metal atoms in their lowest (nsnp) 3 P 2 state are exceptionally long lived and can be trapped magnetically. The nonspherical atomic structure leads to anisotropic long-range interactions between two metastable alkaline-earth-metal atoms. The anisotropy affects the rotational motion of the diatomic system and couples states of different rotational quantum numbers. This paper develops a tensorial decomposition of the most important long-range interaction operators, and a systematic inclusion of molecular rotations, in the presence of an external magnetic field. This analysis illuminates the nature of the coupling between the various degrees of freedom. The consequences are illustrated by application to a system of practical interest: metastable 88 Sr. Using atomic parameters determined in a nearly ab initio calculation, we compute adiabatic potential-energy curves. The anisotropic interatomic interaction, in combination with the applied magnetic field, is demonstrated to induce the formation of a long-range molecular potential well. This curve correlates to two fully polarized, low-field seeking atoms in a rotational s-wave state. The coupling among molecular rotational states controls the existence of the potential well, and its properties vary as a function of magnetic-field strength, thus allowing the scattering length in this state to be tuned. The scattering length of metastable 88 Sr displays a resonance at a field of 339 G

Metal Complexation with Chitosan and its Grafted Copolymer

International Nuclear Information System (INIS)

Abo-Hussen, A.A.; Elkholy, S.S.; Elsabee, M.Z.

2005-01-01

The adsorption of M (II); Co (II), Ni (If), Cu (II), Zn (II) and Cd (II) from aqueous solutions by chitosan flakes and beads have been studied. The maximum up-take of M (II) ions on chitosan beads was greater than on flakes. Batch adsorption experiments were carried out as a function of ph, agitation period and initial concentration of the metal ions. A ph of 6.0 was found to be optimum for M (II) adsorption on chitosan flakes and beads. The uptake of the ions was determined from the changes in its concentration, as measured by ultraviolet and visible spectroscopy. The metal ions uptake of chitosan grafted with vinyl pyridine (VP) is higher than that of the chitosan. The experimental data of the adsorption equilibrium from M (II)-solutions correlated well with the Langmuir and Freundlich equations. Several spectroscopic methods have been used to study the formation of the polymer/metal cation complex. The cation coordination is accompanied by proton displacement off the polymer or by fixation of a hydroxide ion in aqueous solutions. The largest ionic displacement is observed with Cu (II) and Zn (II) demonstrating the largest affinity of chitosan for these ions. The FT-IR spectral of the complexes show that both the amino and hydroxyl groups of chitosan participated in the chelation process. The ESR spectra of Cu-complex show an absorption at gi 2.06, g// = 2.23, A// x 10-4 (cm-1) = 160 and G = 3.8 indicating the formation of square planar structure. The adsorption of M (II) ions followed the sequence Cu (II) > Zn (II) > Cd (II) > Ni (II) > Co (II), this order seems to be independent on the size and the physical form of chitosan. SEM shows small membranous structure on the surface of chitosan flakes as compared to Cu (Il)- chitosan complex. EDTA was used for the desorption studies

New complex-dryers with RE for coatings

International Nuclear Information System (INIS)

Ge, G.

1998-01-01

Full text: The complex coating dryers are produced with good 2-Ethylhexanoic acid, rare earths and other metals. Simply using such a complex drier can get the total effect instead of the traditional dryers such as Co, Mn, Pb, Zn, Ca etc. It has advantages of saving quantity, decreasing cost, simplifying process, making the operation convenient, good quality, good stability and without Pb. Invention patent of China requisition number is 95119867.X

Complexes of rare earths with hydrazide of salicylic acid

Energy Technology Data Exchange (ETDEWEB)

Abashmadze, M Sh; Pirtskhalava, N I; Kharitonov, Yu Ya; Machkhoshvili, R I [Tbilisskij Gosudarstvennyj Univ. (USSR); AN SSSR, Moscow. Inst. Obshchej i Neorganicheskoj Khimii; Moskovskij Khimiko-Tekhnologicheskij Inst. (USSR))

1978-10-01

Complex compounds M(HOC/sub 6/H/sub 4/CONNH/sub 2/)/sub 3/ xnH/sub 2/O, where M is one of the following metals and n=0 or 1, have been obtained in the reactions of salts (chlorides or nitrates) of praseodymium, neodymium, europium, gadolinium, erbium, thulium or lutecium with salicylic acid hydrazide in a weakly alkaline medium. Some properties and infrared absorption spectra of the compounds obtained have been studied.

Structures of metal complexes with anions of di(hydroxymethyl)phosphinic and di(chloromethyl)phosphinic acids

International Nuclear Information System (INIS)

Sergienko, V.S.; Aleksandrov, G.G.

2001-01-01

The structural peculiarities of the different metals [Cu, Ni, rare earths (La, Nd, Er, Lu), Ag, Li, Na, Sr] with anions of di-substituted monophosphonic acids - di(hydroxymethyl) phosphonic acid (HOCH 2 ) 2 PO 2 - (L 1 ) and di(chloromethyl) phosphonic acid (ClCH 2 ) 2 PO 2 - (L 2 ), and the methods of coordinating ligands L 1 and L 2 with these metals were viewed. Coordination number of metal decreases from eight in the case of La, Nd to seven for Er, and further to six for Lu with decreasing size of rare earth element. M-O bond lengths decrease the same way. The LiL 2 · H 2 O structure was determined, Li atom shows tetrahedron coordination by three oxygen atoms of the three ligands L 2 and atom O(ω) of water molecule. The ligand L 1 are acting as a tetradentate chelate μ 3 -bridge function in the structure of the Sr(L 1 ) 2 compound. The interval of Sr-O distances comprises 2.521 - 2.683 A [ru

Environmental and Body Concentrations of Heavy Metals at Sites Near and Distant from Industrial Complexes in Ulsan, Korea.

Science.gov (United States)

Sung, Joo Hyun; Oh, Inbo; Kim, Ahra; Lee, Jiho; Sim, Chang Sun; Yoo, Cheolin; Park, Sang Jin; Kim, Geun Bae; Kim, Yangho

2018-01-29

Industrial pollution may affect the heavy metal body burden of people living near industrial complexes. We determined the average concentrations of atmospheric heavy metals in areas close to and distant from industrial complexes in Korea, and the body concentrations of these heavy metals in residents living near and distant from these facilities. The atmospheric data of heavy metals (lead and cadmium) were from the Regional Air Monitoring Network in Ulsan. We recruited 1,148 participants, 872 who lived near an industrial complex ("exposed" group) and 276 who lived distant from industrial complexes ("non-exposed" group), and measured their concentrations of blood lead, urinary cadmium, and urinary total mercury. The results showed that atmospheric and human concentrations of heavy metals were higher in areas near industrial complexes. In addition, residents living near industrial complexes had higher individual and combined concentrations (cadmium + lead + mercury) of heavy metals. We conclude that residents living near industrial complexes are exposed to high concentrations of heavy metals, and should be carefully monitored. © 2018 The Korean Academy of Medical Sciences.