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1

Secondary Deuterium Isotope Effects with Lanthanide(III)Silver(I) NMR Shift Reagents  

Microsoft Academic Search

Secondary deuterium isotope effects have been observed for nitrogen- and oxygen- containing donors in the presence of lanthanide NMR shift reagents. In each case the shifts observed in the NMR spectrum of the partially deuterated compound were larger than those for the non-deuterated analog. It is generally postulated that the greater inductive effect of deuterium compared to hydrogen causes the

Thomas J. Wenzel

1984-01-01

2

NMR shift reagents  

SciTech Connect

This practical guide to current and potential users of lanthanide shift reagents (LSR) describes the selection of a LSR and the experimental techniques necessary to prepare and properly employ the various types of LSR. It gives a thorough review of previous literature reports in which lanthanide tris chelates and binuclear lanthanide-silver shift reagents were used in organic solvents to study achiral and chiral substrates, with particular focus on the sterochemical and conformational information obtained through use of LSR. It describes LSR suitable for use in aqueous solutions as well as computer fitting of lanthanide shift data through the dipolar shift equation. Other valuable information includes over 800 structures and 1500 references.

Wenzel, T.J.

1987-01-01

3

Determination of diastereomeric purity of tranylcypromine sulfate by proton magnetic resonance spectroscopy with lanthanide shift reagent.  

PubMed

Use of proton nuclear magnetic resonance spectroscopy and the lanthanide shift reagent, Eu(hfc)3, resulted in a simple and reliable method for determination of the diastereomeric purity of trans-2-phenylcyclopropylamine sulfate (tranylcypromine sulfate). Eu(hfc)3 effectively simplified the complex overlapping pattern of the 5 non-equivalent phenyl protons to a virtually first order pattern. At a shift reagent to substrate molar ratio of 0.75, and a substrate concentration of 0.25M (as the free base) in CDCl3, the resonances for the cis- and trans-ortho-phenyl protons at 11.39 and 9.99 ppm, respectively, were sufficiently resolved to be of use in quantitative work. Analysis of synthetic diastereomeric mixtures of 2-phenylcyclopropylamine sulfate by the proposed method yielded results that were in close agreement with the expected values. The mean recovery (SD) of trans-diastereomer was 100.51% (0.40) (n = 6). Levels of less than 2% of cis-diastereomer were measurable in cis-trans mixtures. PMID:2759985

Hanna, G M; Lau-Cam, C A

1989-01-01

4

Lanthanide Shift Reagents. Paper 22 The Influence of Mixed Silver\\/Praseodymium Shift Reagents on the Proton NMR Spectra of Heteroaromatics  

Microsoft Academic Search

Previous work in these laboratories and elsewhere has pointed to the value of a mixture of lanthanide fod chelates with silver fod or with silver trifluoroacetate in simplifying the H NMR spectra of aryl substrates which do not possess the conventional (O or N) donor groups (fod = 2,2-dimethyl-6,6,7,7,8,8,8-heptafluoro-3,5-octane dionate).

D. M. Rackham

1981-01-01

5

Determination of enantiomeric purity of tranylcypromine sulfate by proton magnetic resonance spectroscopy with chiral lanthanide shift reagent.  

PubMed

Optimum experimental conditions were developed for determination of the optical purity of samples of tranylcypromine sulfate by proton magnetic resonance spectroscopy after complexation with the chiral lanthanide chelate Eu(hfc)3. At a substrate concentration of 0.25M (0.125M as sulfate) in CDCl3 and an Eu(hfc)3 to substrate molar ratio of 1, the methine proton geminal to the amino group in the cyclopropane ring showed the largest induced shift and largest enantiomeric induced shift difference. From the relative intensities of the resolved (+)-CH-NH2 protons (15.77 ppm) and (-)-CH-NH2 proton (16.04 ppm), the enantiomeric purity and percentage compositions were readily calculated. The mean +/- SD recovery of (+)-tranylcypromine sulfate from synthetic enantiomeric mixtures was 101.02 +/- 2.59 (n = 6). PMID:2759984

Hanna, G M; Lau-Cam, C A

1989-01-01

6

Metal chelate complexes as nuclear magnetic resonance shift reagents, paramagnetic relaxation reagents, and fuel additives  

SciTech Connect

Water-soluble paramagnetic relaxation reagents for carbon-13 and nitrogen-15 NMR were developed. The Fe(III), Cr(III), Gd(III), and Mn(II) complexes of DTPA are effective relaxation reagents. They can be added to a sample to decrease the relaxation times of carbons or nitrogens not bonded to hydrogen, and supress the nuclear Overhouser effect for carbons or nitrogens that are bonded to hydrogen. Through the use of these reagents, pulse angles can be increased and scan times can be decreased, resulting in better signal intensities in shorter times. Quantitative /sup 13/NMR spectra can also be obtained with these reagents. A fuel additive consisting of the mixed rare earth chelates with the new ligand, 2,2,7-trimethy-13,5-octanedione, was synthesized and evaluated. Tests have shown that this additive is stable in gasoline, cleans carbonaceous material from interior engine surfaces, and increases the research octane number of gasoline.

Wenzel, T.J.

1981-01-01

7

Exploring Crown Ethers as Shift Reagents for Ion Mobility Spectrometry  

PubMed Central

A series of crown ethers, 12-crown-4, 15-crown-5, 18-crown-6, and dibenzo-30-crown-10, are examined as a possible means of shifting the mobilities of peptide ions. In this approach, a crown ether is added to a solution containing a mixture of peptides and is electrosprayed into the gas phase in order to create distributions of peptide-crown complexes. The ion complexes have different mobilities than the naked peptide ions, and the crown ether molecules appear to interact specifically with basic sites in the peptides thus providing some sequence selectivity. After the peptide-crown complexes are separated by ion mobility spectrometry, the ions can be collisionally activated to dissociate the complex (forming the naked peptide ions) prior to m/z analysis. The overall effect is that complex formation shifts peptide ions to different regions of the mobility spectrum, extending the ability to resolve components. The approach is illustrated by examining isobaric dipeptides as well as a combinatorial library containing 27 tripeptides. Cross sections for the series of crown ether ions and complexes that are observed are reported.

Hilderbrand, Amy E.; Myung, Sunnie; Clemmer, David E.

2008-01-01

8

Comparative Study of Ion Interaction Reagents for the Separation of Lanthanides by Reversed-Phase High Performance Liquid Chromatography (RP-HPLC)  

Microsoft Academic Search

A study of two ion interaction reagents (IIRs) viz. n-octadecane sulphonate (C18-sulphonate) and eicosyl sulphate (C20-sulphate) was carried out for the separation of lanthanides by reversed-phase high performance liquid chromatography (RP–HPLC). The objective of the study was to identify a suitable IIR offering long term adsorption onto the RP column, thereby obviating the need to introduce the IIR in the

P. G. Jaison; Pranaw Kumar; Vijay M. Telmore; Suresh K. Aggarwal

2009-01-01

9

Biological and clinical aspects of Lanthanide coordination compounds.  

PubMed

The coordinating chemistry of lanthanides, relevant to the biological, biochemical and medical aspects, makes a significant contribution to understanding the basis of application of lanthanides, particularly in biological and medical systems. The importance of the applications of lanthanides, as an excellent diagnostic and prognostic probe in clinical diagnostics, and an anticancer material, is remarkably increasing. Lanthanide complexes based X-ray contrast imaging and lanthanide chelates based contrast enhancing agents for magnetic resonance imaging (MRI) are being excessively used in radiological analysis in our body systems. The most important property of the chelating agents, in lanthanide chelate complex, is its ability to alter the behaviour of lanthanide ion with which it binds in biological systems, and the chelation markedly modifies the biodistribution and excretion profile of the lanthanide ions. The chelating agents, especially aminopoly carboxylic acids, being hydrophilic, increase the proportion of their complex excreted from complexed lanthanide ion form biological systems. Lanthanide polyamino carboxylate-chelate complexes are used as contrast enhancing agents for Magnetic Resonance Imaging. Conjugation of antibodies and other tissue specific molecules to lanthanide chelates has led to a new type of specific MRI contrast agents and their conjugated MRI contrast agents with improved relaxivity, functioning in the body similar to drugs. Many specific features of contrast agent assisted MRI make it particularly effective for musculoskeletal and cerebrospinal imaging. Lanthanide-chelate contrast agents are effectively used in clinical diagnostic investigations involving cerebrospinal diseases and in evaluation of central nervous system. Chelated lanthanide complexes shift reagent aided (23)Na NMR spectroscopic analysis is used in cellular, tissue and whole organ systems. PMID:18365075

Misra, Sudhindra N; Gagnani, Minaz A; M, Indira Devi; Shukla, Ram S

2004-01-01

10

Biological and Clinical Aspects of Lanthanide Coordination Compounds  

PubMed Central

The coordinating chemistry of lanthanides, relevant to the biological, biochemical and medical aspects, makes a significant contribution to understanding the basis of application of lanthanides, particularly in biological and medical systems. The importance of the applications of lanthanides, as an excellent diagnostic and prognostic probe in clinical diagnostics, and an anticancer material, is remarkably increasing. Lanthanide complexes based X-ray contrast imaging and lanthanide chelates based contrast enhancing agents for magnetic resonance imaging (MRI) are being excessively used in radiological analysis in our body systems. The most important property of the chelating agents, in lanthanide chelate complex, is its ability to alter the behaviour of lanthanide ion with which it binds in biological systems, and the chelation markedly modifies the biodistribution and excretion profile of the lanthanide ions. The chelating agents, especially aminopoly carboxylic acids, being hydrophilic, increase the proportion of their complex excreted from complexed lanthanide ion form biological systems. Lanthanide polyamino carboxylate-chelate complexes are used as contrast enhancing agents for Magnetic Resonance Imaging. Conjugation of antibodies and other tissue specific molecules to lanthanide chelates has led to a new type of specific MRI contrast agents and their conjugated MRI contrast agents with improved relaxivity, functioning in the body similar to drugs. Many specific features of contrast agent assisted MRI make it particularly effective for musculoskeletal and cerebrospinal imaging. Lanthanide-chelate contrast agents are effectively used in clinical diagnostic investigations involving cerebrospinal diseases and in evaluation of central nervous system. Chelated lanthanide complexes shift reagent aided 23Na NMR spectroscopic analysis is used in cellular, tissue and whole organ systems.

Misra, Sudhindra N.; M., Indira Devi; Shukla, Ram S.

2004-01-01

11

Peptide-lanthanide cation equilibria in aqueous phase. I. Bound shifts for L-carnosine-praseodymium complexes  

NASA Astrophysics Data System (ADS)

L-Carnosine complexes of Pr 3+ were characterized in aqueous solution by 1H NMR and potentiometric titration. A rigorous treatment of chemical shifts and pH variation data with lanthanide concentration is presented. Two different forms of the peptide ligand, forming simultaneously two complexes, were taken into account. At low pH values the cation is only coordinated at the carboxylate site of the ligand in a weak complex ( ?2 = 6) whereas in neutral solution a stronger complex ( ?1 = 37) is present as a consequence of the deprotonation of the imidazole ring. The computation of induced bound shifts † 2 and ?1 for resonating nuclei of the peptide in both forms yields consistent figures. These provide the experimental basis for a conformational model which is usually not obtainable for labile complexes with low stability constants.

Mossoyan, J.; Asso, M.; Benlian, D.

12

Shifts in protein charge state distributions with varying redox reagents in nanoelectrospray triple quadrupole mass spectrometry  

Microsoft Academic Search

The influence of a number of redox reagents on the charge state distribution in nanoelectrospray mass spectrometry was examined\\u000a using cytochrome c and ubiquitin. The redox active species investigated were: 1,4-benzoquinone, quinhydrone, tetracyanoquinodimethane\\u000a (TCNQ), hydroquinone, and ascorbic acid. The redox active species was mixed with the protein sample before injection into\\u000a the nanoelectrospray emitter, and mass spectra were acquired using

Cheng Zhao; Troy D. Wood

2005-01-01

13

In vivo measurements of intra- and extracellular Na+ and water in the brain and muscle by nuclear magnetic resonance spectroscopy with shift reagent.  

PubMed Central

The introduction of new paramagnetic shift reagents in the nuclear magnetic resonance (NMR) method has made it possible to distinguish intra- and extracellular ions in tissues or organs in vitro. We measured the intra- and extracellular 23Na and 1H in vivo in the gerbil brain and skeletal muscle by NMR spectroscopy employing the shift reagent, dysprosium triethylenetetraminehexaacetate (Dy[TTHA]3-). Without Dy(TTHA)3-, the 23Na and 1H signals were seen only as single peaks, but gradual intravenous infusion of Dy(TTHA)3- separated these signals into two peaks, respectively. The unshifted peaks reflected the intracellular 23Na and 1H signals, while the shifted peaks reflected the extracellular signals. In the brain spectra, an additional small peak, which represented intravascular signals, was detected and its intensity increased after injection of papaverine hydrochloride. The present method is advantageous over the microelectrode technique because of its nondestructiveness and its capability for obtaining intra- and extracellular volume information from measurements of the 1H spectra, the peaks of which reflect the intra- and extracellular water amounts. The intracellular Na+ increase associating with increased cellular volume after ouabain in the muscle was clearly visualized by this method. The technique is clearly of use for physiological and pathophysiological studies of organs.

Naritomi, H; Kanashiro, M; Sasaki, M; Kuribayashi, Y; Sawada, T

1987-01-01

14

Stereochemistry of the intramolecular shift of the C-C bond in the reactions of cyclopropene compounds with electrophilic reagents  

SciTech Connect

The characteristic direction in the reactions of cyclopropene compounds with electrophilic reagents leads to the formation of acyclic products, which can in principle have the E and Z configurations. Earlier it was shown that the E isomer is formed preferentially in the reaction of 1-methylcyclopropene with bromine and almost exclusively in the reaction with N-bromosuccinimide. In the present communication the authors give stereochemical data on the reaction of 1-methylcyclopropene with deuterium chloride in CH/sub 3/COOD.

Kartashov, V.R.; Afanas'ev, P.S.; Skorobogatova, E.V.; Chertkov, V.A.; Ermolaeva, V.N.; Sergeev, N.M.; Zefirov, N.S.

1986-09-20

15

Method bacterial endospore quantification using lanthanide dipicolinate luminescence  

NASA Technical Reports Server (NTRS)

A lanthanide is combined with a medium to be tested for endospores. The dipicolinic acid released from the endospores binds the lanthanides, which have distinctive emission (i.e., luminescence) spectra, and are detected using photoluminescence. The concentration of spores is determined by preparing a calibration curve generated from photoluminescence spectra of lanthanide complex mixed with spores of a known concentration. A lanthanide complex is used as the analysis reagent, and is comprised of lanthanide ions bound to multidentate ligands that increase the dipicolinic acid binding constant through a cooperative binding effect with respect to lanthanide chloride. The resulting combined effect of increasing the binding constant and eliminating coordinated water and multiple equilibria increase the sensitivity of the endospore assay by an estimated three to four orders of magnitude over prior art of endospore detection based on lanthanide luminescence.

Ponce, Adrian (Inventor); Venkateswaran, Kasthuri J. (Inventor); Kirby, James Patrick (Inventor)

2007-01-01

16

Luminescent lanthanide chelates and methods of use  

DOEpatents

The invention provides lanthanide chelates capable of intense luminescence. The celates comprise a lanthanide chelator covalently joined to a coumarin-like or quinolone-like sensitizer. Exemplary sensitzers include 2- or 4-quinolones, 2- or 4-coumarins, or derivatives thereof e.g. carbostyril 124 (7-amino-4-methyl-2-quinolone), coumarin 120 (7-amino-4-methyl-2-coumarin), coumarin 124 (7-amino-4-(trifluoromethyl)-2-coumarin), aminomethyltrimethylpsoralen, etc. The chelates form high affinity complexes with lanthanides, such as terbium or europium, through chelator groups, such as DTPA. The chelates may be coupled to a wide variety of compounds to create specific labels, probes, diagnostic and/or therapeutic reagents, etc. The chelates find particular use in resonance energy transfer between chelate-lanthanide complexes and another luminescent agent, often a fluorescent non-metal based resonance energy acceptor. The methods provide useful information about the structure, conformation, relative location and/or interactions of macromolecules.

Selvin, Paul R. (Berkeley, CA); Hearst, John (Berkeley, CA)

1997-01-01

17

Fracture-resistant lanthanide scintillators  

DOEpatents

Lanthanide halide alloys have recently enabled scintillating gamma ray spectrometers comparable to room temperature semiconductors (<3% FWHM energy resolutions at 662 keV). However brittle fracture of these materials upon cooling hinders the growth of large volume crystals. Efforts to improve the strength through non-lanthanide alloy substitution, while preserving scintillation, have been demonstrated. Isovalent alloys having nominal compositions of comprising Al, Ga, Sc, Y, and In dopants as well as aliovalent alloys comprising Ca, Sr, Zr, Hf, Zn, and Pb dopants were prepared. All of these alloys exhibit bright fluorescence under UV excitation, with varying shifts in the spectral peaks and intensities relative to pure CeBr.sub.3. Further, these alloys scintillate when coupled to a photomultiplier tube (PMT) and exposed to .sup.137Cs gamma rays.

Doty, F. Patrick (Livermore, CA)

2011-01-04

18

Surfactant-sensitized post-column reaction with xylenol orange for the determination of lanthanides by ion chromatography  

Microsoft Academic Search

The presence of the cationic surfactants cetylpyridinium chloride and hexadecyltrimethylammonium bromide in an alkaline 40% methanol medium was found to enhance sensitivity when xylenol orange is employed as the post-column reaction reagent for the determination of lanthanides by dynamic ion chromatography. Detection of individual lanthanides was carried out at 618 nm after separation by cation-exchange chromatography with gradient elution on

Eduardo A. Gautier; Raquel T. Gettar; Roberto E. Servant; Daniel A. Batistoni

1997-01-01

19

Homogeneous detection of avidin based on switchable lanthanide luminescence.  

PubMed

We have developed switchable lanthanide luminescence-based binary probe technology for homogeneous detection of avidin, which is a tetrameric protein. Two different nonluminescent label moieties--a light-absorbing antenna ligand and a lanthanide ion carrier chelate--were conjugated to separate biotins, which is known as avidin's natural ligand. The assay was based on binding of the two differently labeled biotins on separate binding sites on the target protein and consequent self-assembly of a luminescent complex from the two label moieties. Specific luminescence signal was observed only at the presence of the target protein. The characteristics of the switchable lanthanide luminescence assay were compared to the reference assay, based on lanthanide resonance energy transfer. Both assays had a limit of detection in the low-picomolar concentration range; however, the lanthanide chelate complementation-based assay had wider dynamic range and its optimization was more straightforward. The switchable lanthanide luminescence technology could be further applied to generic protein detection, using reagents that are analogous to the proximity ligation assay principle. PMID:22070371

Karhunen, Ulla; Rosenberg, Jaana; Lamminmäki, Urpo; Soukka, Tero

2011-12-01

20

Hyperfine interactions at lanthanide impurities in Fe  

NASA Astrophysics Data System (ADS)

The magnetic hyperfine field and electric-field gradient at isolated lanthanide impurities in an Fe host lattice are calculated from first principles, allowing a qualitative and quantitative understanding of an experimental data set collected over the past 40years . It is demonstrated that the common local density approximation leads to quantitatively and qualitatively wrong results, while the LDA+U method performs much better. In order to avoid pitfalls inherent to the LDA+U method, a combination of free ion calculations and “constrained density matrix” calculations is proposed and tested. Quantitative results for the exchange field and crystal field parameters are obtained ( Bexc=+420T , B04=-1000cm-1 , B06=-800cm-1 ), showing in particular how crystal field effects influence the hyperfine fields for the lightest and heaviest lanthanides. The hyperfine fields are shown to be dominated by the 4f orbital contribution, with small corrections due to the spin dipolar and Fermi contact fields. The latter is found to be constant for all lanthanides, a feature that is understood by a modified version of the well-known core polarization mechanism for 3d hyperfine fields. Spin dipolar fields and electric-field gradients have apart from a 4f contribution a surprisingly strong contribution due to the completely filled lanthanide 5p orbitals—the mechanism behind this is explained. The lanthanide 4f spin moment is found to couple antiparallel to the magnetization of the Fe lattice, in agreement with the model of Campbell and Brooks. There is strong evidence for a delocalization-localization transition that is shifted from Ce to at least Pr and maybe further up to Sm. This shift is interpreted in terms of the effective pressure felt by lanthanides in Fe. Implications for resolving ambiguities in the determination of delocalization in pure lanthanide metals under pressure are discussed. For the localized lanthanides, Yb is shown to be divalent in this host lattice, while all others are trivalent (including Eu). The temperature dependence of the hyperfine fields is discussed as well.

Torumba, D.; Vanhoof, V.; Rots, M.; Cottenier, S.

2006-07-01

21

The Lanthanide Contraction Revisited  

SciTech Connect

A complete, isostructural series of lanthanide complexes (except Pm) with the ligand TREN-1,2-HOIQO has been synthesized and structurally characterized by means of single-crystal X-ray analysis. All complexes are 1D-polymeric species in the solid state, with the lanthanide being in an eight-coordinate, distorted trigonal-dodecahedral environment with a donor set of eight unique oxygen atoms. This series constitutes the first complete set of isostructural lanthanide complexes with a ligand of denticity greater than two. The geometric arrangement of the chelating moieties slightly deviates across the lanthanide series, as analyzed by a shape parameter metric based on the comparison of the dihedral angles along all edges of the coordination polyhedron. The apparent lanthanide contraction in the individual Ln-O bond lengths deviates considerably from the expected quadratic decrease that was found previously in a number of complexes with ligands of low denticity. The sum of all bond lengths around the trivalent metal cation, however, is more regular, showing an almost ideal quadratic behavior across the entire series. The quadratic nature of the lanthanide contraction is derived theoretically from Slater's model for the calculation of ionic radii. In addition, the sum of all distances along the edges of the coordination polyhedron show exactly the same quadratic dependency as the Ln-X bond lengths. The universal validity of this coordination sphere contraction, concomitant with the quadratic decrease in Ln-X bond lengths, was confirmed by reexamination of four other, previously published, almost complete series of lanthanide complexes. Due to the importance of multidentate ligands for the chelation of rare-earth metals, this result provides a significant advance for the prediction and rationalization of the geometric features of the corresponding lanthanide complexes, with great potential impact for all aspects of lanthanide coordination.

Seitz, Michael; Oliver, Allen G.; Raymond, Kenneth N.

2007-04-19

22

Thermolysis of lanthanide dithiocarbamate complexes  

SciTech Connect

Polycrystalline lanthanide sulfide materials were formed at low temperatures using a single-source precursor based on the lanthanide dithiocarbamate complex. The synthesis temperatures are generally lower than standard solid state preparations, avoid toxic sulfurizing gases and provide a convenient route to prepare lanthanide chalcogenide nanoparticles. Depending on the reaction conditions and oxophilicity of the lanthanide, the sulfide material was formed with oxidized products including oxysulfides, oxysulfates and the oxide. - Graphical abstract: Polycrystalline lanthanide sulfide materials were formed at low temperatures using a single-source precursor based on the lanthanide dithiocarbamate complex.

Boncher, William L.; Regulacio, Michelle D. [Department of Chemistry, Georgetown University, Washington DC 20057 (United States); Stoll, Sarah L., E-mail: sls55@georgetown.ed [Department of Chemistry, Georgetown University, Washington DC 20057 (United States)

2010-01-15

23

Photovoltgaic cell including wavelength shifter comprising lanthanide chelate fluorophores based on dihydrophridine condensation products  

SciTech Connect

This patent describes an improvement in a photovoltaic device of the type comprising a photovoltaic cell having a face. The improvement comprises a wavelength-shifting coating on its face, the wavelength-shifting coating comprising the reaction product of a {beta}-diketone, an aldehyde, an amine, and a lanthanide metal ion, the reaction product being a lanthanide metal ion chelate and the wavelength-shifting coating increasing the portion of the solar spectrum available to the cell for conversion into electricity.

Dakubu, S.

1990-01-02

24

Immobilized enzymes as analytical reagents  

Microsoft Academic Search

Immobilized enzymes are becoming increasingly popular as analytical reagents because of their reusability, stability, and\\u000a sensitivity to many inhibitors that would seriously interfere in assays using soluble enzymes. In this article, some of the\\u000a kinetic and catalytic effects of immobilized enzymes in analysis will be discussed. The shift of the activity-pH profile curves\\u000a on immobilization, the changes in temperature dependence.

George G. Guilbault

1982-01-01

25

Handling Pyrophoric Reagents  

SciTech Connect

Pyrophoric reagents are extremely hazardous. Special handling techniques are required to prevent contact with air and the resulting fire. This document provides several methods for working with pyrophoric reagents outside of an inert atmosphere.

Alnajjar, Mikhail S.; Haynie, Todd O.

2009-08-14

26

Luminescent macrocyclic lanthanide complexes  

DOEpatents

The present invention provides a novel class of macrocyclic compounds as well as complexes formed between a metal (e.g., lanthanide) ion and the compounds of the invention. Preferred complexes exhibit high stability as well as high quantum yields of lanthanide ion luminescence in aqueous media without the need for secondary activating agents. Preferred compounds incorporate hydroxy-isophthalamide moieties within their macrocyclic structure and are characterized by surprisingly low, non-specific binding to a variety of polypeptides such as antibodies and proteins as well as high kinetic stability. These characteristics distinguish them from known, open-structured ligands.

Raymond, Kenneth N. (Berkeley, CA); Corneillie, Todd M. (Campbell, CA); Xu, Jide (Berkeley, CA)

2012-05-08

27

Aromatic triamide-lanthanide complexes  

DOEpatents

The present invention provides luminescent lanthanide metal chelates comprising a metal ion of the lanthanide series and a complexing agent comprising at least one phthalamidyl moiety. Also provided are probes incorporating the phthalamidyl ligands of the invention and methods utilizing the ligands of the invention and probes comprising the ligands of the invention.

2013-10-08

28

Development of a Regenerable Strip Reagent for Treatment of Acidic, Radioactive Waste with Cobalt Dicarbollide?based Solvent Extraction Processes  

Microsoft Academic Search

A regenerable methylamine carbonate (MAC)\\/diethylenetriamine pentaacetic acid (DTPA) strip solution has been developed, as a collaborative effort between the Khlopin Radium Institute (KRI) and the Idaho National Engineering and Environmental Laboratory (INEEL), for the stripping of actinides, lanthanides, Cs, and Sr from cobalt dicarbollide?based solvent extraction processes. Methodology and experimental results of developing this strip reagent and a distillation method

Jack D. Law; R. Scott Herbst; Dean R. Peterman; Terry A. Todd; Valeriy N. Romanovskiy; Vasily A. Babain; Igor V. Smirnov

2005-01-01

29

Reagents, Compositions, Weight Loss  

NSDL National Science Digital Library

This is a short experimental study of what happens to aluminum hydroxide, silicic acid, magnesium oxide, and calcium carbonate (or reagents of instructors choice) when they are heated to 110 and 1200 degrees. Students determine the formula and calculate the mole percent and weight percent of each element and oxide in each reagent. They heat the samples and calculate percentage weight loss or gain. Finally, they write a lab report summarizing their results. Be sure to have students save their samples for later use in a lab that introduces X-ray diffraction.

Perkins, Dexter

30

Citrate based ``TALSPEAK`` lanthanide-actinide separation process  

SciTech Connect

The potential hazard posed to future generations by long-lived radionuclides such as the transuranic elements (TRU) is perceived as a major problem associated with the use of nuclear power. TRU wastes have to remain isolated from the environment for ``geological`` periods of time. The costs of building, maintaining, and operating a ``geological TRU repository`` can be very high. Therefore, there are significant economical advantages in segregating the relatively low volume of TRU wastes from other nuclear wastes. The chemical behavior of lanthanides and actinides, 4f and 5f elements respectively, is rather similar. As a consequence, the separation of these two groups is difficult. The ``TALSPEAK`` process (Trivalent Actinide Lanthanide Separations by Phosphorus-reagent Extraction from Aqueous Complexes) is one of the few means available to separate the trivalent actinides from the lanthanides. The method is based on the preferential complexation of the trivalent actinides by an aminopolyacetic acid. Cold experiments showed that by using citric acid the deleterious effects produced by impurities such as zirconium are greatly reduced.

Del Cul, G.D.; Bond, W.D.; Toth, L.M.; Davis, G.D.; Dai, S.; Metcalf, D.H.

1994-09-01

31

Preparation of Paramyxovirus Reagents.  

National Technical Information Service (NTIS)

The two reports, from the contracts listed in the supplementary note, comprise part of the NIAID program for the production of reagents: (1) Parke, Davis and Co. has prepared and tested all five of the following bulk agent pools and build antiserum pools:...

W. B. Beardmore J. K. Noel

1967-01-01

32

Flavonoids as Analytical Reagents  

Microsoft Academic Search

Compounds from the flavonoid family, while exhibiting a wide range of biological effects, are interesting reagents for analytical purposes as well. They form complexes with several p-, d-, and f-electron metals, which could be employed in the determination of these metal ions in different kinds of samples by various techniques. This article presents and discusses the application of flavonoid compounds

Krystyna Pyrzynska; Anna P?kal

2011-01-01

33

RP-IPC with a lactic acid modified eluent for separation and determination of lanthanide ions  

SciTech Connect

In this paper, a modified method for the separation and determination of Rare Earth Elements in solution is developed. Lanthanide ions were separated by Reversed-Phase Ion Pair Chromatography using a mobile phase gradient of pH and lactic acid concentration. A post-column reaction with 4-(2 pyridyl)azo resorcinol was carried out for the spectrophotometric detection of solutes. The derivatizing reagent composition was optimized for good solute sensitivity and long-term reagent stability. Method limitations due to inadequate instrumentation are presented and discussed.

Vera-Avila, L.E.; Camacho, E. (Analytical Chemistry Dept., Facultad de Quimica, Univ. Nacional Autonoma de Mexico, 04510 D.F. (Mexico))

1992-01-01

34

Hybridization Assay by Time-Resolved Capillary Gel Electrophoresis with a Lanthanide Chelate  

Microsoft Academic Search

Capillary electrophoresis of crude biological samples with time-resolved fluorescence (TRF) detection enables elimination\\u000a of interference from organic fluorophores and from light scattering. Because the fluorescence lifetime of biological substances\\u000a and impurities overlaps the fluorescence lifetime of conventional labeling dyes, TRF detection with conventional organic labeling\\u000a dyes suffers from background fluorescence. In this work, we synthesized a luminescent lanthanide chelating reagent

Keiko Sumitomo; Takahisa Ito; Motoyasu Sasaki; Yoshinori Yamaguchi

2008-01-01

35

Use of soft heterocyclic N-donor ligands to separate actinides and lanthanides.  

PubMed

The removal of the most long-lived radiotoxic elements from used nuclear fuel, minor actinides, is foreseen as an essential step toward increasing the public acceptance of nuclear energy as a key component of a low-carbon energy future. Once removed from the remaining used fuel, these elements can be used as fuel in their own right in fast reactors or converted into shorter-lived or stable elements by transmutation prior to geological disposal. The SANEX process is proposed to carry out this selective separation by solvent extraction. Recent efforts to develop reagents capable of separating the radioactive minor actinides from lanthanides as part of a future strategy for the management and reprocessing of used nuclear fuel are reviewed. The current strategies for the reprocessing of PUREX raffinate are summarized, and some guiding principles for the design of actinide-selective reagents are defined. The development and testing of different classes of solvent extraction reagent are then summarized, covering some of the earliest ligand designs right through to the current reagents of choice, bis(1,2,4-triazine) ligands. Finally, we summarize research aimed at developing a fundamental understanding of the underlying reasons for the excellent extraction capabilities and high actinide/lanthanide selectivities shown by this class of ligands and our recent efforts to immobilize these reagents onto solid phases. PMID:22867058

Hudson, Michael J; Harwood, Laurence M; Laventine, Dominic M; Lewis, Frank W

2013-04-01

36

Hypersensitive pseudoquadrupole transitions in lanthanides  

Microsoft Academic Search

It is pointed out that the absorption lines of the lanthanides that are peculiarly sensitive to changes in the ligands are consistent with the selection rules for quadrupole radiation within the 4f shell. A number of sources for this sensitivity are examined, and it is concluded that it owes its origin to the inhomogeneity of the dielectric. According to this

Chr. Klixbüll Jørgensen; B. R. Judd

1964-01-01

37

LANTHANIDE ENHANCE LUMINESCENCE (LEL) WITH ONE AND TWO PHOTON EXCITATION OF QUANTUM DYES LANTHANIDE (III) - MACROCYCLES  

EPA Science Inventory

Title: Lanthanide Enhance Luminescence (LEL) with one and two photon excitation of Quantum Dyes? Lanthanide(III)-Macrocycles Principal Author: Robert C. Leif, Newport Instruments Secondary Authors: Margie C. Becker, Phoenix Flow Systems Al Bromm, Virginia Commonw...

38

Toxicological and cytophysiological aspects of lanthanides action  

Microsoft Academic Search

Lanthanides, also called rare-earth elements, are an interesting group of 15 chemi- cally active, mainly trivalent, f-electronic, silvery-white metals. In fact, lanthanides are not as rare as the name implies, except for promethium, a radioactive artificial ele- ment not found in nature. The mean concentrations of lanthanides in the earth's crust are comparable to those of life-important elements like iodine,

Artur Pa; Piotr Czekaj

2000-01-01

39

Lanthanide mixed ligand chelates for DNA profiling and latent fingerprint detection  

NASA Astrophysics Data System (ADS)

It is our aim to develop a universally applicable latent fingerprint detection method using lanthanide (rare-earth) complexes as a source of luminescence. Use of these lanthanide complexes offers advantages on several fronts, including benefits from large Stokes shifts, long luminescence lifetimes, narrow emissions, ability of sequential assembly of complexes, and chemical variability of the ligands. Proper exploitation of these advantages would lead to a latent fingerprint detection method superior to any currently available. These same characteristics also lend themselves to many of the problems associated with DNA processing in the forensic science context.

Menzel, E. R.; Allred, Clay

1997-02-01

40

21 CFR 866.4100 - Complement reagent.  

Code of Federal Regulations, 2013 CFR

...AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunology Laboratory Equipment and Reagents § 866.4100 Complement reagent. (a)...

2013-04-01

41

Reagents for Identifying 'Mycoplasma pneumoniae'.  

National Technical Information Service (NTIS)

The invention is related to reagents which specifically recognize the human pathogen Mycoplasma pneumoniae and no other Mycoplasma species or organism belonging to the class Mollicutes. More particularly, the present invention is related to an immunoassay...

L. D. Olson

1989-01-01

42

Separation of actinides from lanthanides  

DOEpatents

An organic extracting solution and an extraction method useful for separating elements of the actinide series of the periodic table from elements of the lanthanide series, where both are in trivalent form is described. The extracting solution consists of a primary ligand and a secondary ligand, preferably in an organic solvent. The primary ligand is a substituted monothio-1,3-dicarbonyl, which includes a substituted 4-acyl-2-pyrazolin-5-thione, such as 4-benzoyl-2,4- dihydro-5-methyl-2-phenyl-3H-pyrazol-3-thione (BMPPT). The secondary ligand is a substituted phosphine oxide, such as trioctylphosphine oxide (TOPO).

Smith, B.F.; Jarvinen, G.D.; Ryan, R.R.

1988-03-31

43

Separation of actinides from lanthanides  

SciTech Connect

This patent describes an organic extracting solution and an extraction method useful for separating elements of the actinide series of the periodic table from elements of the lanthanide series, where both are in trivalent form. The extracting solution consists of a primary ligand and a secondary ligand, preferably in an organic solvent. The primary ligand is a substituted monothio-1,3-dicarbonyl, which include a substituted 4-acyl-2-pyrazolin-5-thione, such as 4-benzoyl-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-thione (BMPPT). The secondary ligand is a substituted phosphine oxide, such as trioctylphosphine oxide (TOPO).

Smith, B.F.; Jarvinen, G.D.; Ryan, R.R.

1989-09-19

44

Exploiting lanthanide luminescence in supramolecular assemblies.  

PubMed

Lanthanide ions, due to their unique photo-physical characteristics, have attracted considerable attention in recent years. Their long lifetimes, sharp, well-defined emission bands, and designable environmental sensitivity make them ideal for integration into switchable supramolecular assemblies where emission can report on local conformation and/or coupled energy levels (redox state). The immobilisation of lanthanide containing constructs on interfaces facilitates device integration, the fabrication of advanced sensory and molecular electronic platforms and presents a means by which conformational dynamics within molecular assemblies can be analysed. In this feature article we discuss the current and potential applications for lanthanide luminescence in supramolecular, switchable and surface bound architectures. PMID:24664123

Lehr, Joshua; Beer, Paul D; Faulkner, Stephen; Davis, Jason J

2014-06-01

45

Scalar static polarizabilities of lanthanides and actinides  

NASA Astrophysics Data System (ADS)

We calculate scalar static polarizabilities for lanthanides and actinides, the atoms with open 4f or 5f subshells. We show that polarizabilities of the low states are approximately the same for all states of a given configuration, and we present a way of calculating them reducing valence space to just two or three valence electrons occupying 6s and 5d states for lanthanides or 7s and 6d states for actinides, while 4f and 5f states are considered to be in the core. The configuration interaction technique is used to calculate polarizabilities of lanthanides and actinides for all states of the 4fn6s2 and 4fn -16s25d configurations of lanthanides and all states of the 5fn7s2 and 5fn -17s26d configurations of actinides. Polarizability of the electron core (including f orbitals) has been calculated in the random-phase approximation.

Dzuba, V. A.; Kozlov, A.; Flambaum, V. V.

2014-04-01

46

The role of lanthanides in optical materials  

SciTech Connect

A survey is presented of the use of the lanthanides as chemical components in transmitting optical materials and as activators in materials for luminescent, electro-optic, magneto-optic, and various photosensitive applications.

Weber, M.J.

1995-05-01

47

[Supplies: inventory control and reagents].  

PubMed

The main relevant features useful for the management of reagents and consumables as well as documents to be developed to meet the requirements of the accreditation standard ISO/FDIS 15189-2012 are listed. This article is intended to help the medical laboratory to get mandatory accreditation. PMID:23765026

Szymanowicz, A

2013-06-01

48

New Chemical Reagents in Mycology.  

National Technical Information Service (NTIS)

Spot color test reactions used for the chemical determination or study of fungi are discussed. The particular reagents tested on a number of different species of edible and poisonous mushrooms were: (1) two solutions of p-diazobenzene sulfonic acid hydroc...

K. Micka

1977-01-01

49

Review Article: The Effects of Radiation Chemistry on Solvent Extraction 3: A Review of Actinide and Lanthanide Extraction  

SciTech Connect

The partitioning of the long-lived ?-emitters and the high-yield fission products from dissolved nuclear fuel is a key component of processes envisioned for the safe recycling of nuclear fuel and the disposition of high-level waste. These future processes will likely be based on aqueous solvent extraction technologies for light water reactor fuel and consist of four main components for the sequential separation of uranium, fission products, group trivalent actinides and lanthanides, and then trivalent actinides from lanthanides. Since the solvent systems will be in contact with highly radioactive solutions, they must be robust toward radiolytic degradation in an irradiated mixed organic, aqueous acidic environment. Therefore, an understanding of their radiation chemistry is important to the design of a practical system. In the first paper in this series we reviewed the radiation chemistry of irradiated aqueous nitric acid and the tributyl phosphate ligand for uranium extraction in the first step of these extractions. In the second, we reviewed the radiation chemistry of the ligands proposed for use in the extraction of cesium and strontium fission products. Here, we review the radiation chemistry of the ligands that might be used in the third step in the series of separations, for the group extraction of the lanthanides and actinides. This includes traditional organophosphorous reagents such as CMPO and HDEHP, as well as novel reagents such as the amides and diamides currently being investigated.

Bruce J. Mincher; Giuseppe Modolo; Stephen P. Mezyk

2009-12-01

50

21 CFR 866.3360 - Lymphocytic choriomeningitis virus serological reagents.  

Code of Federal Regulations, 2013 CFR

... false Lymphocytic choriomeningitis virus serological reagents. 866.3360 Section...866.3360 Lymphocytic choriomeningitis virus serological reagents. (a) Identification. Lymphocytic choriomeningitis virus serological reagents are devices...

2013-04-01

51

Extraction of actinide and lanthanide complexonates in potassium carbonate-poly(ethylene glycol)-water two-phase aqueous system  

SciTech Connect

An extraction system based on poly(ethylene glycol) for preconcentrating, isolating and separating actinides, is proposed. The extraction of actinides and lanthanides in a potassium carbonate-poly(ethylene glycol)-water two-phase aqueous system in the presence of various complexones was studied. Trivalent actinides are quantitatively extracted by poly(ethylene glycol) from potassium carbonate solutions in a system with Xylenol Orange and alizarin complexone. Under these conditions, uranium (VI) and plutonium (IV) are extracted inappreciably into a phase enriched with poly(ethylene glycol), so that they can be separated from trivalent actinides with a separation factor of 10/sup 2/-10/sup 3/. To separate actinides and lanthanides, two complexones were introduced into the system, one of which served as an extractant, and the other as a masking reagent. The best results were obtained for a mixture of Xylenol Orange and hydroxyethylidenediphosphonic acid. The separation coefficients of americium and europium are 4.5-5.6.

Molochnikova, N.P.; Shkinev, V.M.; Spivakov, B.Ya.; Zolotov, Yu.A.; Myasoedov, B.F.

1988-09-01

52

Selective Separation of Trivalent Actinides from Lanthanides by Aqueous Processing with Introduction of Soft Donor Atoms  

SciTech Connect

Implementation of a closed loop nuclear fuel cycle requires the utilization of Pu-containing MOX fuels with the important side effect of increased production of the transplutonium actinides, most importantly isotopes of Am and Cm. Because the presence of these isotopes significantly impacts the long-term radiotoxicity of high level waste, it is important that effective methods for their isolation and/or transmutation be developed. Furthermore, since transmutation is most efficiently done in the absence of lanthanide fission products (high yield species with large thermal neutron absorption cross sections) it is important to have efficient procedures for the mutual separation of Am and Cm from the lanthanides. The chemistries of these elements are nearly identical, differing only in the slightly stronger strength of interaction of trivalent actinides with ligand donor atoms softer than O (N, Cl-, S). Research being conducted around the world has led to the development of new reagents and processes with considerable potential for this task. However, pilot scale testing of these reagents and processes has demonstrated the susceptibility of the new classes of reagents to radiolytic and hydrolytic degradation. In this project, separations of trivalent actinides from fission product lanthanides have been investigated in studies of 1) the extraction and chemical stability properties of a class of soft-donor extractants that are adapted from water-soluble analogs, 2) the application of water soluble soft-donor complexing agents in tandem with conventional extractant molecules emphasizing fundamental studies of the TALSPEAK Process. This research was conducted principally in radiochemistry laboratories at Washington State University. Collaborators at the Radiological Processing Laboratory (RPL) at the Pacific Northwest National Laboratory (PNNL) have contributed their unique facilities and capabilities, and have supported student internships at PNNL to broaden their academic experience. New information has been developed to qualify the extraction potential of a class of pyridine-functionalized tetraaza complexants indicating potential single contact Am-Nd separation factors of about 40. The methodology developed for characterization will find further application in our continuing efforts to synthesize and characterize new reagents for this separation. Significant new insights into the performance envelope and supporting information on the TALSPEAK process has also been developed.

Kenneth L. Nash

2009-09-22

53

Nuclear magnetic resonance structural studies of an axially symmetric lanthanide ion chelate in aqueous solution  

NASA Astrophysics Data System (ADS)

The complexes of the macrocyclic ligand 1,4, 7-triazacyclononane- N,N',N?-triacetic acid (NOTA) with the paramagnetic trivalent lanthanide canons have been examined by proton and 13C magnetic resonance spectroscopy. Lanthanide-induced shifts (LIS) have been measured for all proton and carbon resonances in nine paramagnetic Ln(NOTA) complexes at 25 and 70°C. At both temperatures the ethylene protons appear as a pair of resonances forming an AA'XX' splitting pattern (visible only in the Eu(NOTA) spectrum) while the acetate protons remain a singlet. The directions and magnitudes of the 1H and 13C shifts indicate they are dominated by contact interactions in most of the Ln(NOTA) complexes. The 13C spectrum of Pr(NOTA) provides evidence that more than one chelate structure is present in solution. The addition of LiCl to Pr(NOTA) and Eu(NOTA) samples results in significant shifts in the bound 1H and 13C resonances whereas the spectra of Dy(NOTA) and Yb(NOTA) do not change significantly when LiCl is added. These results, along with observed breaks in plots of experimental LIS data versus theoretical pseudocontact and contact shift values, suggest that the early members of the lanthanide ion series form mixed complexes with NOTA in aqueous solution, some with NOTA bound as a hexadentate chelate and some a pentadentate species with one unbound acetate group. The smaller trivalent lanthanide cations (Dy ? Yb) appear to form complexes containing only hexadentate chelated NOTA. The contact and pseudocontact contributions to each of the observed LIS have been separated and the resulting pseudocontact shifts for the Dy ? Yb complexes agree reasonably well with those calculated using the axial symmetry model. The 1H and 13C relaxation rates determined for three Ln(NOTA) complexes indicate that the smaller lanthanide cations fit into the triazamacrocyclic cavity better than do the larger ions resulting in structurally more rigid Ln(NOTA) complexes.

Sherry, A. D.; Singh, M.; Geraldes, C. F. G. C.

54

Electrospray mass spectra of lanthanides  

SciTech Connect

The electrospray mass spectra of several elements in the lanthanide series are presented with the focus being on understanding the basic processes that occur to yield such spectra. The solution chemistry and the physical properties of the elements have a profound effect on the type of species observed in a mass spectrum. To perform elemental analysis by electrospray mass spectrometry, harsh declustering conditions are typically used. This results in a spectrum consisting of the bare metal ion (Ln[sup +] or Ln[sup 2+]) and molecular ions (LnO[sup +]) such as oxides as well as contributions due to matrix ions. The sampling conditions required to obtain such spectra require a large potential difference between the sampling plate and the skimmer at the atmosphere to vacuum interface, resulting in efficient collision-induced dissociation conditions. To monitor the process, a frame by frame illustration is used where the potential difference between the sampling plate and skimmer is increased in increments and the resultant spectra are captured. With this procedure, the dominant processes may be highlighted and explained step by step and a clearer understanding of the processes involved is obtained. 43 refs., 7 refs., 1 tab.

Stewart, I.I.; Horlick, G. (Univ. of Alberta, Edmonton, Alberta (Canada))

1994-11-15

55

21 CFR 866.3330 - Influenza virus serological reagents.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Influenza virus serological reagents. 866...Serological Reagents § 866.3330 Influenza virus serological reagents. (a) Identification. Influenza virus serological reagents are...

2010-04-01

56

21 CFR 866.3035 - Arizona spp. serological reagents.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Arizona spp. serological reagents. 866.3035... Serological Reagents § 866.3035 Arizona spp. serological reagents. (a) Identification. Arizona spp. serological reagents are...

2013-04-01

57

21 CFR 866.3350 - Leptospira spp. serological reagents.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Leptospira spp. serological reagents. 866...Serological Reagents § 866.3350 Leptospira spp. serological reagents. (a) Identification. Leptospira spp. serological reagents...

2010-04-01

58

21 CFR 866.3350 - Leptospira spp. serological reagents.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Leptospira spp. serological reagents. 866...Serological Reagents § 866.3350 Leptospira spp. serological reagents. (a) Identification. Leptospira spp. serological reagents...

2009-04-01

59

21 CFR 866.3500 - Rickettsia serological reagents.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Rickettsia serological reagents. 866.3500...Serological Reagents § 866.3500 Rickettsia serological reagents. (a) Identification. Rickettsia serological reagents are devices...

2010-04-01

60

21 CFR 866.3500 - Rickettsia serological reagents.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Rickettsia serological reagents. 866.3500...Serological Reagents § 866.3500 Rickettsia serological reagents. (a) Identification. Rickettsia serological reagents are devices...

2009-04-01

61

21 CFR 866.3380 - Mumps virus serological reagents.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Mumps virus serological reagents. 866.3380... Serological Reagents § 866.3380 Mumps virus serological reagents. (a) Identification. Mumps virus serological reagents consist...

2010-04-01

62

21 CFR 866.3380 - Mumps virus serological reagents.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Mumps virus serological reagents. 866.3380... Serological Reagents § 866.3380 Mumps virus serological reagents. (a) Identification. Mumps virus serological reagents consist...

2009-04-01

63

21 CFR 866.3400 - Parainfluenza virus serological reagents.  

Code of Federal Regulations, 2013 CFR

... 2013-04-01 false Parainfluenza virus serological reagents. 866.3400 Section...Reagents § 866.3400 Parainfluenza virus serological reagents. (a) Identification. Parainfluenza virus serological reagents are devices...

2013-04-01

64

21 CFR 866.3085 - Brucella spp. serological reagents.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Brucella spp. serological reagents. 866...Serological Reagents § 866.3085 Brucella spp. serological reagents. (a) Identification. Brucella spp. serological reagents are...

2009-04-01

65

21 CFR 866.3085 - Brucella spp. serological reagents.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Brucella spp. serological reagents. 866...Serological Reagents § 866.3085 Brucella spp. serological reagents. (a) Identification. Brucella spp. serological reagents are...

2010-04-01

66

Sensing Lanthanide Metal Content in Biological Tissues with Magnetic Resonance Spectroscopy  

PubMed Central

The development and validation of MRI contrast agents consisting of a lanthanide chelate often requires a determination of the concentration of the agent in ex vivo tissue. We have developed a protocol that uses 70% nitric acid to completely digest tissue samples that contain Gd(III), Dy(III), Tm(III), Eu(III), or Yb(III) ions, or the MRI contrast agent gadodiamide. NMR spectroscopy of coaxial tubes containing a digested sample and a separate control solution of nitric acid was used to rapidly and easily measure the bulk magnetic susceptibility (BMS) shift caused by each lanthanide ion and gadodiamide. Each BMS shift was shown to be linearly correlated with the concentration of each lanthanide ion and gadodiamide in the 70% nitric acid solution and in digested rat kidney and liver tissues. These concentration measurements had outstanding precision, and also had good accuracy for concentrations ?10 mM for Tm(III) Eu(III), and Yb(III), and ?3 mM for Gd(III), gadodiamide, and Dy(III). Improved sample handling methods are needed to improve measurement accuracy for samples with lower concentrations.

Hingorani, Dina V.; Gonzalez, Sandra I.; Li, Jessica F.; Pagel, Mark D.

2013-01-01

67

Recovery system containing lanthanide-crosslinked polymers  

SciTech Connect

A recovery system is described comprising: (a) a subterranean formation; (b) a well bore penetrating at least a portion of the subterranean formation; and (c) a composition capable of forming a gel present in at least a portion of the well bore, wherein the composition comprises: (i) a crosslinkable polymer (CP) selected from the group consisting of heteropolysaccharides obtained by the fermentation of starch-derived sugar, ammonium salts, and alkali metal salts; (ii) a lanthanide; and (iii) an ingredient selected from the group consisting of gel breakers, sequestering agents, proppants for use in hydraulically fracturing, particulate agents for forming a gravel pack, and base precursors selected from the group consisting of ammonium slats, urea, thiourea, and mixtures of these. A second recovery system is described in which the gel composition comprises: (i) a CP selected from the group consisting of acrylic acid-acrylamide copolymers, acrylic acid-methacrylamide copolymers, polyacrylamides, polymethacrylamides, partially hydrolyzed polyacrylamides, partially hydrolyzed polymethacrylamides, polyvinyl alcohol, polyvinyl acetate, polyvinyl pyrrolidone, polyalkyleneoxides, lignosulfonates, ammonium salts, alkali metal salts, and alkaline earth salts of lignosulfonates; and (ii) a crosslinking agent selected from the group consisting of lanthanides, sequestered lanthanides, and mixtures thereof. A third system is described in which the gel composition comprises: (i) a CP, hydroxyethylcellulose; and (ii) a crosslinking agent selected from the group consisting of lanthanides, sequestered lanthanides, and mixtures thereof. A fourth system is described in which the gel composition comprises: (i) a CP selected from the group consisting of polyvinyl alcohol, polyvinyl acetate, polyvinyl pyrrolidone, polyalkyleneoxides, lignosulfonates, ammonium salts, alkali metal salts, and alkaline earth salts of lignosulfonates; and (ii) a lanthanide.

Dovan, H.T.; Hutchins, R.D.

1993-07-13

68

Renewable-reagent electrochemical sensor  

DOEpatents

A new electrochemical probe(s) design allowing for continuous (renewable) reagent delivery is described. The probe comprises an integrated membrane sampling/electrochemical sensor that prevents interferences from surface-active materials and greatly extends the linear range. The probe(s) is useful for remote or laboratory-based monitoring in connection with microdialysis sampling and electrochemical measurements of metals and organic compounds that are not readily detected in the absence of reacting with the compound. Also disclosed is a method of using the probe(s). 19 figs.

Wang, J.; Olsen, K.B.

1999-08-24

69

Separation of lanthanides from trivalent actinides, the role of aqueous-phase soft-donor complexing agents  

SciTech Connect

Closing the nuclear fuel cycle to reduce storage volumes and times requires advanced separation processes, among which is the separation of trivalent actinides from lanthanides that are present in the waste. A proven system is TALSPEAK, utilizing polyamino-carboxylates for this group separation. However, the narrow pH range these molecules require complicates their use. Soft-donor molecules that may complex actinides at low pH have been investigated. Results indicate that, although DTPA gives the best selectivity, all molecules tested showed preference for americium. The solubility of some reagents at low pH suggests the need for further development. (authors)

Nilsson, Mikael; Hoch, Cortney; Meier, G. Patrick; Nash, Kenneth L. [Chemistry Department, Washington State University, P.O. Box 644630, Pullman, WA (United States)

2008-07-01

70

Spectroscopic Study of the Use of Lanthanide Metalloporphyrins as Sensors for Benzene and Acetonitrile Detection in Aqueous Studies  

NASA Astrophysics Data System (ADS)

This work entails the research on lanthanide metalloporphyrins for their potential use as chemical sensors for benzene and acetonitrile. This research is of importance due to the health implications that benzene and acetonitrile cause; benzene is a known carcinogen and acetonitrile is a known lung irritant. The use of UV-Vis spectroscopy, Fluorescence spectroscopy, Gaussian DFT, and X-ray diffraction crystallography were used in the characterization and analysis of the lanthanide porphyrin complexes. Europium, terbium, dysprosium, cerium, and gadolinium were the lanthanides used in conjunction with 5,10,15,20-tetraphenylporphyrin, TPP and 5,10,15,20-tetrakissulfonato porphyrin, TBSP. Based on the luminescence spectroscopy and UV-Vis spectroscopy data, an aqueous sensor for acetonitrile and benzene was shown to be promising. Among the compounds studied, EuTPP and DyTPP complexes exposed to sodium hydroxide showed promising results for sensing acetonitrile due to significant narrowing of the soret band and the decrease of Q bands in the UV-Vis spectra, along with the blue shifting of luminescence emission spectra. On the other hand, the CeTPP and EuTPP solutions show promise as benzene sensors due to the blue shifting of emission luminescence and variation in intensity. Based on the lanthanide TBSP complexes, TbTBSP was shown to be a promising sensor for acetonitrile due to the narrow soret band, decreased Q bands, and blue shifted emission spectra. EuTBSP, DyTBSP, and TbTBSP were shown to be promising for benzene sensors. Benzene stabilized the TBSP at a higher energy state, S2, to facilitate the energy transfer to the lanthanide ions.

Crawford, Carlos Lemarr, Jr.

71

Radial distribution of electron density in lanthanide atoms and the observed lanthanide contraction  

Microsoft Academic Search

The metal-halogen distances in the molecules of LuCI3, LaBr3, GdBr3, and LuBr3, measured by gas electron diffraction, have been compared with the quantum-mechanic al orbital radii of the electron density according to Waber and Cromer for the atoms, atomic cores, and trivalent ions of the lanthanides. It has been established that the experimental value of the lanthanide contraction A(La-Lu) coincides

K. S. Krasnov; N. I. Giricheva; G. V. Girichev

1977-01-01

72

Lanthanide-based imaging of protein-protein interactions in live cells.  

PubMed

In order to deduce the molecular mechanisms of biological function, it is necessary to monitor changes in the subcellular location, activation, and interaction of proteins within living cells in real time. Förster resonance energy-transfer (FRET)-based biosensors that incorporate genetically encoded, fluorescent proteins permit high spatial resolution imaging of protein-protein interactions or protein conformational dynamics. However, a nonspecific fluorescence background often obscures small FRET signal changes, and intensity-based biosensor measurements require careful interpretation and several control experiments. These problems can be overcome by using lanthanide [Tb(III) or Eu(III)] complexes as donors and green fluorescent protein (GFP) or other conventional fluorophores as acceptors. Essential features of this approach are the long-lifetime (approximately milliseconds) luminescence of Tb(III) complexes and time-gated luminescence microscopy. This allows pulsed excitation, followed by a brief delay, which eliminates nonspecific fluorescence before the detection of Tb(III)-to-GFP emission. The challenges of intracellular delivery, selective protein labeling, and time-gated imaging of lanthanide luminescence are presented, and recent efforts to investigate the cellular uptake of lanthanide probes are reviewed. Data are presented showing that conjugation to arginine-rich, cell-penetrating peptides (CPPs) can be used as a general strategy for the cellular delivery of membrane-impermeable lanthanide complexes. A heterodimer of a luminescent Tb(III) complex, Lumi4, linked to trimethoprim and conjugated to nonaarginine via a reducible disulfide linker rapidly (?10 min) translocates into the cytoplasm of Maden Darby canine kidney cells from the culture medium. With this reagent, the intracellular interaction between GFP fused to FK506 binding protein 12 (GFP-FKBP12) and the rapamycin binding domain of mTOR fused to Escherichia coli dihydrofolate reductase (FRB-eDHFR) were imaged at high signal-to-noise ratio with fast (1-3 s) image acquisition using a time-gated luminescence microscope. The data reviewed and presented here show that lanthanide biosensors enable fast, sensitive, and technically simple imaging of protein-protein interactions in live cells. PMID:24144069

Rajendran, Megha; Yapici, Engin; Miller, Lawrence W

2014-02-17

73

Homogeneous Catalysis Using Lanthanide Amidinates and Guanidinates  

NASA Astrophysics Data System (ADS)

For decades, the organometallic chemistry of the rare earth elements was largely dominated by the cyclopentadienyl ligand and its ring-substituted derivatives. A hot topic in current organolanthanide chemistry is the search for alternative ligand sets which are able to satisfy the coordination requirements of the large lanthanide cations. Among the most successful approaches in this field is the use of amidinate ligands of the general type [RC(NR ' )2]- (R = H, alkyl, aryl; R ' = alkyl, cycloalkyl, aryl, SiMe3) which can be regarded as steric cyclopentadienyl equivalents. Closely related are the guanidinate anions of the general type [R2NC(NR ' )2]- (R = alkyl, SiMe3; R ' = alkyl, cycloalkyl, aryl, SiMe3). Two amidinate or guanidinate ligands can coordinate to a lanthanide ion to form a metallocene-like coordination environment which allows the isolation and characterization of stable though very reactive amide, alkyl, and hydride species. Mono- and trisubstituted lanthanide amidinate and guanidinate complexes are also readily available. Various rare earth amidinates and guanidinates have turned out to be very efficient homogeneous catalysts, for example, for ring-opening polymerization reactions. This article covers the success story of lanthanide amidinates and guanidinates and their transition from mere laboratory curiosities to efficient homogeneous catalysts.

Edelmann, Frank T.

74

Lanthanide discs chill well and relax slowly.  

PubMed

The synthesis, structure and magnetic properties of two isostructural heptametallic lanthanide discs are reported, showing single molecule magnet (SMM) behaviour with a large energy barrier for the dysprosium analogue and a large magnetocaloric effect (MCE) for the gadolinium analogue. PMID:21647513

Sharples, Joseph W; Zheng, Yan-Zhen; Tuna, Floriana; McInnes, Eric J L; Collison, David

2011-07-21

75

Extraction separation of tervalent americium and lanthanides in the presence of some soft and hard donors and dicarbollide  

SciTech Connect

Some combinations of extractants involving dicarbollide as one component for the separation of Am/Ln were studied. Extraction by TOPO is not influenced to a great extent by the presence of dicarbollide, and TPTZ in the presence of dicarbollide is ineffective for the extraction from 0.1 M HNO[sub 3]. General aspects of the selectivity of lanthanides and of Am/Ln separation in the presence of various reagents are discussed with emphasis on the difficulties of the separation of Am from light lanthanides. A new extraction procedure by dicarbollide in the presence of an excess of o-phenanthroline over the mineral acid is proposed. This led to the highest separation factors D[sub Am]/D[sub Eu] (20-34) from 0.1 M HNO[sub 3]. The behavior of other lanthanides is similar to that of Eu, with a maximum distribution ratio for Nd (D[sub Nd]/D[sub Eu] = 2). 27 refs., 10 figs.

Rais, J.; Tachimori, S. (Japan Atomic Emergy Research Institute, Ibaraki (Japan))

1994-06-01

76

Method of Dispensing Reagent Chemicals in Space.  

National Technical Information Service (NTIS)

A procedure for the slow, controlled release of a reagent chemical in a reaction solution is described. A liquid gel is prepared, and a reagent chemical is added while the gel is still liquid. The gel solution thereby formed is poured into a storage conta...

P. G. Barber J. H. Coleman W. J. Debnam

1988-01-01

77

POLYMER-SUPPORTED REAGENTS FOR MOLECULAR SEPARATIONS  

Microsoft Academic Search

A Hammett study of the complexing abilities of various polymer-supported reagents for phenols, anilines, and benzoic acids is described. For each polymeric reagent, the percent absorbed of each family of compounds is correlated with the Hammett substituent constants. A carboxylic acid resin shows no interaction with phenols and benzoic acids; only a weak interaction with anilines is found since 25%

Spiro D. Alexandratos; Paul T. Kaiser

1989-01-01

78

TREATMENT OF MTBE USING FENTON'S REAGENT  

EPA Science Inventory

This paper addresses the removal of MTBE from water, using Fenton's Reagent. Although complete mineralization of MTBE by Fenton's Reagent was not achieved, greater than 99% destruction of MTBE was realized. This was accomplished at a Fe+2:H2O2 ratio of 1:1 and one hour of contact...

79

A traceless Staudinger reagent to deliver diazirines.  

PubMed

A triarylphosphine reagent that reacts with organic azides to install amide-linked diazirines is reported. This traceless Staudinger reagent reacts with complex organic azides to yield amide-linked diazirines, thus expanding the scope of the utility of both azide and diazirine chemistry. PMID:24059816

Ahad, Ali M; Jensen, Stephanie M; Jewett, John C

2013-10-01

80

Partial Molar Volumes for Lanthanide Sesquioxides in Sodium Silicate Melts  

NASA Astrophysics Data System (ADS)

Lanthanides are of great interest in igneous petrology as trace indicators of magmatic processes that control the origin and evolution of igneous rocks. A key to the petrogenetic modelling of magmatic processes and to determine the phase diagrams of lanthanide host phases is the accurate determination of the physico-chemical and thermodynamic properties of lanthanide-containing materials, such as the volumetric properties of lanthanide-bearing silicate melts. Therefore, we have undertaken to provide a new reliable volumetric data set for lanthanide-bearing silicate melts which allows the available models in the literature to be extended to lanthanide-bearing melts. For this purpose, the densities of various lanthanide-bearing silicate melts distributed along various pseudo-binary joins, where the end-members are Na-disilicate and one of the lanthanide sesquioxides (i.e., Ce2O3, Pr2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, Tb2O3, Dy2O3, Ho2O3, Er2O3, Tm2O3 and Yb2O3), have been measured using the double-bob Archimedean method. The present results show that the addition of any lanthanide to Na-disilicate leads to an increase in the melt density and that the melt density increases with increasing atomic number of the lanthanide. From the present density data set, the molar volumes of these melts have been calculated and the partial molar volumes of each lanthanide sesquioxide in these melts have been determined using a linear regression through each pseudo-binary join (i.e., Na-disilicate - lanthanide sesquioxide). This study indicates ideal behaviour with respect to the molar volume (i.e., a linear variation of the molar volume along each pseudo-binary join) for Na-silicate melts containing up to 10 mol% of lanthanide oxide. Comparison between the partial molar volumes of lanthanide sesquioxides obtained in this study and the molar volumes of molten lanthanide sesquioxides given in the literature raise the possibility however that this ideality is not maintained along the entire Na-disilicate - lanthanide sesquioxide pseudo-binary joins. Excess volumes of mixing appear to be required to describe the combined volumetric data set.

Courtial, P.; Dingwell, D. B.

2004-12-01

81

Degradable Conjugates from Oxanorbornadiene Reagents  

PubMed Central

Oxanorbornadienedicarboxylate (OND) reagents were explored for purposes of binding and releasing drugs from serum albumins as representative macromolecular carriers. Being highly reactive Michael acceptors, ONDs form adducts with thiols and amines, which then undergo retro-Diels–Alder fragmentation. The study of more than 30 model adducts revealed a number of modifications that can be used to influence adduct stability. For the most reactive OND linkers, the labeling of the single available bovine serum albumin (BSA) cysteine residue was complete within minutes at mid-micromolar concentration of reactants. While a selectivity of greater than 1000-fold for thiol over amine was observed with model amino acids, the labeling of protein amines with ONDs is fast enough to be practical, as demonstrated by reaction with thiol-depleted BSA. The OND–amine adducts were found to be up to 15 times more stable than OND–thiol adducts, and to be sensitive to acid by virtue of a stereochemically-dependent acceleration of cycloreversion. The release rate of fluorescent cargo from serum albumins was tuned by selecting the coupling partners: the available half-lives ranged from 40 minutes to 7 days at 37 °C. Such versatility of release profiles from protein carriers, controlled by the nature of the OND linkage, is a useful addition to the drug delivery toolbox.

Kislukhin, Alexander A.; Higginson, Cody J.; Hong, Vu P.; Finn, M.G.

2012-01-01

82

Lanthanide acylpyrazolonates: synthesis, properties and structural features  

NASA Astrophysics Data System (ADS)

Data concerning synthesis and structural features of lanthanide acylpyrazolonates including tris-complexes, heteroligand complexes with aromatic N-heterocycles and phosphorus-containing ligands and anionic tetrakis-complexes are summarized. The effect of substituents in the acyl moiety on the structural and luminescence properties of the compounds is considered. The key features of acylpyrazolonate coordination polymers and bis(acylpyrazolonates) of rare earth elements are discussed. The bibliography includes 71 references.

Belousov, Yu A.; Drozdov, Andrey A.

2012-12-01

83

Sorption of lanthanides on smectite and kaolinite  

Microsoft Academic Search

Experiments were carried out to investigate the sorption of the complete lanthanide series (Ln or rare earth elements, REE) on a kaolinite and an a Na-montmorillonite at 22°C over a wide range of pH (3–9). Experiments were conducted at two ionic strengths, 0.025 and 0.5 M, using two different background electrolytes (NaNO3 or NaClO4) under atmospheric conditions or N2 flow

Frédéric Coppin; Gilles Berger; Andreas Bauer; Sylvie Castet; Michel Loubet

2002-01-01

84

Spectral studies of heterocyclic ?-diketonates of actinide, lanthanide, and transition metals  

NASA Astrophysics Data System (ADS)

The results of absorption spectral studies of the 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone chelates of thorium, uranyl, neodymium, gadolinium, gallium, and iron are presented. These neutral chelates exhibit u.v. spectra very similar to that of the ligand, with slight bathochromic or hypsochromic shifts. The solution stability of the complexes in acetonitrile, ethanol, and chloroform was also studied and the lanthanide complexes were found to be the least stable. Sinha's parameter is calculated for the neodymium chelate to determine the relative degree of covalency upon complexation.

Morales, R.; Nekimken, H.; Bartholdi, C. S.; Cunningham, P. T.

85

Lanthanide-cyclodextrin complexes as probes for elucidating optical purity by NMR spectroscopy  

SciTech Connect

A multidentate ligand is bonded to cyclodextrins by the reaction of diethylenetriaminepentaacetic dianhydride with 6-mono- and 2-mono(ethylenediamine) derivatives of cyclodextrin. Adding Dy(III) to the cyclodextrin derivatives enhances the enantiomeric resolution in the [sup 1]H NMR spectra of carbionoxamine maleate, doxylamine succinate, pheniramine maleate, propranolol hydrochloride, and tryptophan. The enhancement is more pronounced with the secondary derivative. The Dy(III)-induced shifts can be used to elucidate the geometry of cyclodextrin-substrate inclusion complexes. Lanthanide-induced shifts are reported for complexes of aspartame, tryptophan, propranolol, and 1-anilino-8-naphthalenesulfonate with cyclodextrins, and the relative magnitudes of the shifts agree with previously reported structures of the complexes. 37 refs., 9 figs., 5 tabs.

Wenzel, T.J.; Bogyo, M.S.; Lebeau, E.L. (Bates College, Lewiston, ME (United States))

1994-06-01

86

Design, synthesis, and evaluation of a lanthanide chelating protein probe: CLaNP-5 yields predictable paramagnetic effects independent of environment.  

PubMed

Immobilized lanthanide ions offer the opportunity to refine structures of proteins and the complexes they form by using restraints obtained from paramagnetic NMR experiments. We report the design, synthesis, and spectroscopic evaluation of the lanthanide chelator, Caged Lanthanide NMR Probe 5 (CLaNP-5) readily attachable to a protein surface via two cysteine residues. The probe causes tunable pseudocontact shifts, alignment, paramagnetic relaxation enhancement, and luminescence, by chelating it to the appropriate lanthanide ion. The observation of single shifts and the finding that the magnetic susceptibility tensors obtained from shifts and alignment analyses are highly similar strongly indicate that the probe is rigid with respect to the protein backbone. By placing the probe at various positions on a model protein it is demonstrated that the size and orientation of the magnetic susceptibility tensor of the probe are independent of the local protein environment. Consequently, the effects of the probe are readily predictable using a protein structure only. These findings designate CLaNP-5 as a protein probe to deliver unambiguous high quality structural restraints in studies on protein-protein and protein-ligand interactions. PMID:18826316

Keizers, Peter H J; Saragliadis, Athanasios; Hiruma, Yoshitaka; Overhand, Mark; Ubbink, Marcellus

2008-11-01

87

Actinide and lanthanide separation process (ALSEP)  

DOEpatents

The process of the invention is the separation of minor actinides from lanthanides in a fluid mixture comprising, fission products, lanthanides, minor actinides, rare earth elements, nitric acid and water by addition of an organic chelating aid to the fluid; extracting the fluid with a solvent comprising a first extractant, a second extractant and an organic diluent to form an organic extractant stream and an aqueous raffinate. Scrubbing the organic stream with a dicarboxylic acid and a chelating agent to form a scrubber discharge. The scrubber discharge is stripped with a simple buffering agent and a second chelating agent in the pH range of 2.5 to 6.1 to produce actinide and lanthanide streams and spent organic diluents. The first extractant is selected from bis(2-ethylhexyl)hydrogen phosphate (HDEHP) and mono(2-ethylhexyl)2-ethylhexyl phosphonate (HEH(EHP)) and the second extractant is selected from N,N,N,N-tetra-2-ethylhexyl diglycol amide (TEHDGA) and N,N,N',N'-tetraoctyl-3-oxapentanediamide (TODGA).

Guelis, Artem V.

2013-01-15

88

Coordination of lanthanides by two polyamino polycarboxylic macrocycles: formation of highly stable lanthanide complexes  

Microsoft Academic Search

The formation constants of a few lanthanide complexes with DOTA (1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid) and TETA (1,4,8,11-tetraazacyclotetradecane-N,N',N'',N'''-tetraacetic acid) have been measured by potentiometric and competition methods. The ligand DOTA forms the most stable lanthanide chelates known so far (log K\\/sub ML\\/ = 28.2-29.2) while the stability of the TETA compounds at 80 °C (log K\\/sub ML\\/ = 14.5-16.5) is comparable to the

M. F. Loncin; J. F. Desreux; E. Merciny

1986-01-01

89

Lanthanide hydroxide nanorods and their thermal decomposition to lanthanide oxide nanorods  

Microsoft Academic Search

Lanthanide hydroxide (La(OH)3, Nd(OH)3, Sm(OH)3, Gd(OH)3, and Dy(OH)3) nanorods were successfully synthesized via a convenient hydrothermal synthetic method using triethylamine as both alkaline agent and complexing agent. The influences of reaction temperature and concentration of triethylamine on the formation of lanthanum hydroxide nanorods were investigated in this paper. Lanthanide oxide (La2O3, Nd2O3, Sm2O3, Gd2O3, and Dy2O3) nanorods could be obtained

Ning Zhang; Ran Yi; Libin Zhou; Guanhua Gao; Rongrong Shi; Guanzhou Qiu; Xiaohe Liu

2009-01-01

90

40 CFR 792.83 - Reagents and solutions.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Reagents and solutions. 792.83 Section 792.83 Protection...Facilities Operation § 792.83 Reagents and solutions. All reagents and solutions in the laboratory areas shall be...

2013-07-01

91

40 CFR 160.83 - Reagents and solutions.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Reagents and solutions. 160.83 Section 160.83 Protection...Facilities Operation § 160.83 Reagents and solutions. All reagents and solutions in the laboratory areas shall be...

2013-07-01

92

21 CFR 866.3740 - Streptococcus spp. serological reagents.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Streptococcus spp. serological reagents. 866...Serological Reagents § 866.3740 Streptococcus spp. serological reagents. (a) Identification. Streptococcus spp. serological...

2010-04-01

93

21 CFR 866.3740 - Streptococcus spp. serological reagents.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Streptococcus spp. serological reagents. 866...Serological Reagents § 866.3740 Streptococcus spp. serological reagents. (a) Identification. Streptococcus spp. serological...

2009-04-01

94

21 CFR 606.65 - Supplies and reagents.  

Code of Federal Regulations, 2010 CFR

... Reagent or solution Frequency of testing Anti-human globulin Each day of use. Blood grouping reagents Do. Lectins Do. Antibody screening and reverse grouping cells Do. Hepatitis test reagents Each run. Syphilis serology...

2010-04-01

95

21 CFR 606.65 - Supplies and reagents.  

Code of Federal Regulations, 2010 CFR

... Reagent or solution Frequency of testing Anti-human globulin Each day of use. Blood grouping reagents Do. Lectins Do. Antibody screening and reverse grouping cells Do. Hepatitis test reagents Each run. Syphilis serology...

2009-04-01

96

21 CFR 864.8100 - Bothrops atrox reagent.  

Code of Federal Regulations, 2013 CFR

...Reagents § 864.8100 Bothrops atrox reagent. (a) Identification. A Bothrops atrox reagent is a device made from snake venom and used to determine blood fibrinogen levels to aid in the evaluation of disseminated intravascular...

2013-04-01

97

21 CFR 866.3480 - Respiratory syncytial virus serological reagents.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 false Respiratory syncytial virus serological reagents. 866.3480... § 866.3480 Respiratory syncytial virus serological reagents. (a) Identification. Respiratory syncytial virus serological reagents are devices...

2013-04-01

98

Inactivation of rabies diagnostic reagents by gamma radiation  

SciTech Connect

Treatment of CVS-11 rabies adsorbing suspensions and street rabies infected mouse brains with gamma radiation resulted in inactivated reagents that are safer to distribute and use. These irradiated reagents were as sensitive and reactive as the nonirradiated control reagents.

Gamble, W.C.; Chappell, W.A.; George, E.H.

1980-11-01

99

Weak alignment of paramagnetic proteins warrants correction for residual CSA effects in measurements of pseudocontact shifts.  

PubMed

Paramagnetic metal ions can induce molecular alignment with respect to the magnetic field. This alignment generates residual anisotropic chemical shifts (RACS) due to nonisotropic averaging over the molecular orientations. Using a 30 kDa protein-protein complex, the RACS effects are shown to be significant for heteronuclear spins with large chemical shift anisotropies, lanthanide ions with large anisotropic magnetic susceptibility tensors, and measurements at high magnetic field. Therefore, RACS must be taken into account when pseudocontact shifts are measured by comparison of chemical shifts observed between complexes with paramagnetic and diamagnetic lanthanide ions. The results are of particular importance when different pseudocontact shifts measured for the 1HN, 15N, and 13C' spins of a peptide group are used to restrain its orientation with respect to the electronic magnetic susceptibility tensor in structure calculations. PMID:16332059

John, Michael; Park, Ah Young; Pintacuda, Guido; Dixon, Nicholas E; Otting, Gottfried

2005-12-14

100

Protein binding to lanthanide(III) complexes can reduce the water exchange rate at the lanthanide.  

PubMed

The GdIII-based magnetic resonance imaging contrast agent MS-325 targets the blood protein serum albumin, resulting in an increased efficacy (relaxivity) as a relaxation agent. MS-325 showed different relaxivities when bound to serum albumin from different species, e.g., r1=30.5 mM-1 s-1 (rabbit) vs 46.3 mM-1 s-1 (human) at 35 degrees C and 0.47 T. To investigate the mechanism for this difference, surrogate complexes were prepared where the GdIII ion was replaced by other LnIII ions. Fluorescence lifetime measurements of the EuIII analogue indicated that the hydration number was q=1 and did not change when bound to either human, rat, rabbit, pig, or dog serum albumin. The YbIII analogue, YbL1, was prepared and characterized by 1H NMR. Line-shape analysis of the paramagnetic-shifted 1H NMR resonances in the presence of increasing amounts of human (HSA) or rabbit (RSA) serum albumin allowed estimation of the transverse relaxation rate, R2, of these resonances for the protein-bound YbL1. The rotational correlation time of YbL1 was calculated from R2, and the Yb-H distance and was tauR=8+/-1 ns when bound to HSA and 13+/-2 ns when bound to RSA. The water exchange rate at the DyIII analogue, DyL1, was determined from variable-temperature R2 measurements at 9.4 T when DyL1 was bound to either HSA or RSA. At 37 degrees C, water exchange at DyL1 was (31+/-5)x10(6) s-1 when bound to HSA but (3.8+/-0.2)x10(6) s-1 when bound to RSA. Slower water exchange upon RSA binding explains the differences in relaxivity observed. The approach of using surrogate lanthanides to identify specific molecular parameters influencing relaxivity is applicable to other protein-targeted GdIII contrast agents. PMID:17425306

Zech, Stephan G; Eldredge, Harriet B; Lowe, Mark P; Caravan, Peter

2007-04-30

101

Shift Registers  

NSDL National Science Digital Library

All About Circuits is a website that âÂÂprovides a series of online textbooks covering electricity and electronics.â Written by Tony R. Kuphaldt, the textbooks available here are wonderful resources for students, teachers, and anyone who is interested in learning more about electronics. This specific section, Shift Registers, is the twelfth chapter in Volume IV âÂÂDigital. A few of the topics covered in this chapter include: Serial-in, serial-out shift register, Parallel-in, parallel-out shift register, and Ring counters. Diagrams and detailed descriptions of concepts are included throughout the chapter to provide users with a comprehensive lesson. Visitors to the site are also encouraged to discuss concepts and topics using the All About Circuits discussion forums (registration with the site is required to post materials).

Kuphaldt, Tony R.

2008-07-18

102

Phthalamide lanthanide complexes for use as luminescent markers  

DOEpatents

The present invention provides luminescent lanthanide metal chelates comprising a metal ion of the lanthanide series and a complexing agent comprising at least one phthalamidyl moiety. Also provided are probes incorporating the phthalamidyl ligands of the invention and methods utilizing the ligands of the invention and probes comprising the ligands of the invention.

Raymond, Kenneth N. (Berkeley, CA); Petoud, Stephane (Berkeley, CA); Cohen, Seth M. (Boston, MA); Xu, Jide (Berkeley, CA)

2003-01-01

103

TRI-2 Propyl Phosphate-Lanthanide Nitrate Complexes  

SciTech Connect

Tri-2-propyl phosphase (T2PP) reacts with lanthanide nitrates to form two series of solid complexes. These complexes were characterized by elemental analyses. X-ray diffraction patterns showed a single structure for each series, and infrared spectra showed that both nitrate and T2PP ligand were coordinated with lanthanide ions. The relative stabilities of the different species are discussed.

McRae, J.R.

2001-08-29

104

Method for providing oxygen ion vacancies in lanthanide oxides  

Microsoft Academic Search

A method for desulfurization of fuel gases resulting from the incomplete combustion of sulfur containing hydrocarbons whereby the gases are treated with lanthanide oxides containing large numbers of oxygen-ion vacancies providing ionic porosity which enhances the ability of the lanthanide oxides to react more rapidly and completely with the sulfur in the fuel gases whereby the sulfur in such gases

D. Alan R. Kay; William G. Wilson

1989-01-01

105

Improved method for extracting lanthanides and actinides from acid solutions  

DOEpatents

A process for the recovery of actinide and lanthanide values from aqueous acidic solutions uses a new series of neutral bi-functional extractants, the alkyl(phenyl)-N,N-dialkylcarbamoylmethylphosphine oxides. The process is suitable for the separation of actinide and lanthanide values from fission product values found together in high-level nuclear reprocessing waste solutions.

Horwitz, E.P.; Kalina, D.G.; Kaplan, L.; Mason, G.W.

1983-07-26

106

21 CFR 866.3370 - Mycobacterium tuberculosis immunofluorescent reagents.  

...2014-04-01 false Mycobacterium tuberculosis immunofluorescent reagents... § 866.3370 Mycobacterium tuberculosis immunofluorescent reagents...Identification. Mycobacterium tuberculosis immunofluorescent...

2014-04-01

107

21 CFR 866.3370 - Mycobacterium tuberculosis immunofluorescent reagents.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 false Mycobacterium tuberculosis immunofluorescent reagents... § 866.3370 Mycobacterium tuberculosis immunofluorescent reagents...Identification. Mycobacterium tuberculosis immunofluorescent...

2012-04-01

108

21 CFR 866.3370 - Mycobacterium tuberculosis immunofluorescent reagents.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 false Mycobacterium tuberculosis immunofluorescent reagents... § 866.3370 Mycobacterium tuberculosis immunofluorescent reagents...Identification. Mycobacterium tuberculosis immunofluorescent...

2011-04-01

109

Remarks on Preparation of Indandione Detection Reagents.  

National Technical Information Service (NTIS)

A modified Claisen condensation with sliced sodium at a higher temperature was recommended for the production of ungranulated charcoal. A new ninhydrin production method by oxidation of benzaldiketohydrinden using available reagents was tried and was unsu...

J. Stepan V. Kral

1985-01-01

110

Accelerating the Discovery of Effective Photonic Reagents.  

National Technical Information Service (NTIS)

A method for accelerating searches for optimal control of photonic reagents is provided. Closed loop feedback is applied to control a quantum system. A direct search deterministic technique is used for refining said closed loop feedback control. A quantum...

H. Rabitz

2005-01-01

111

Preparation and Development of Enterovirus Reagents.  

National Technical Information Service (NTIS)

The selection of three semiannual progress reports describes part of NIAID's Research Reference Reagents Program. Reports are included from (1) Baylor University of Houston, Texas, (2) the California State Department of Public Health of Berkeley and (3) U...

J. L. Melnick E. H. Lennette H. A. Wenner

1967-01-01

112

Recent Applications of Peroxygen Reagents in Hydrometallurgy  

Microsoft Academic Search

The paper reviews development made over the past decade in the application of peroxygnn reagents in hydrometallurgical processes. The reagents are hydrogen peroxide, H202, Caro’s acid, H2MS05, and calcium peroxide, CaO2. Their chemical properties and methods for on-site storage or production are outlined.Most progress has been made in the gold extraction industry, where hydrogen peroxide and calcium peroxide have been

A. J. MONHEMIUS

1992-01-01

113

Lanthanide Chelates as Bilayer Alignment Tools in NMR Studies of Membrane-Associated Peptides  

NASA Astrophysics Data System (ADS)

Theequimolar complex, consisting of the lipid-like, amphiphilic chelating agent 1,11-bis[distearylamino]-diethylenetriamine pentaacetic acid (DTPA-18) and Tm 3+, is shown by deuterium ( 2H) NMR to be useful in aligning bicelle-like model membranes, consisting of dimyristoylphosphatidylcholine (DMPC) and dihexanoylphosphatidylcholine (DHPC). As shown previously (1996, R. S. Prosser et al., J. Am. Chem. Soc. 118, 269-270), in the absence of chelate, the lanthanide ions bind loosely with the lipid phosphate groups and confer the membrane with a sufficient positive magnetic anisotropy to result in parallel alignment (i.e., average bilayer normal along the field). Apparently, DTPA-18 sequesters the lanthanide ions and inserts into the phospholipid bilayer in such a manner that bilayer morphology is preserved over a wide temperature range (35-70°C). The inherent paramagnetic shifts and line broadening effects are illustrated by 2H NMR spectra of the membrane binding peptide, Leu-enkephalin (Lenk- d2, Tyr-(Gly- d2)-Gly-Phe-Leu-OH), in the presence of varying concentrations of Tm 3+, and upon addition of DTPA-18. Two conclusions could be drawn from this study: (1) The addition of Tm 3+ to the bicelle system is consistent with a conformational change in the surface associated peptide, and this effect is shown to be reversed by addition of the chelate, and (2) The paramagnetic shifts are shown to be significantly reduced by addition of chelate.

Prosser, R. S.; Bryant, H.; Bryant, R. G.; Vold, Regitze R.

1999-12-01

114

Reducing temper embrittlement by lanthanide additions  

SciTech Connect

This paper examines the temper embrittlement behavior of a series of 2 1/4%Cr-1%Mo steels with and without lanthanide metal (LnM) additions. The influence of LnM additions asmischmetal or as individual elements is assessed with respect to embrittlement behavior. Results show that LnM form harmless compounds in the matrix with impurities such as P, As, Sn and Sb, thus minimizing segregation-induced embrittlement. Optimum LnM levels well below those dictated from theoretical calculations are sufficient to trap the impurities for a given set of conditions.

Garcia, C.I.; Burke, M.G.; De Ardo, A.J.; Ratz, G.A.

1985-09-01

115

Luminescent lanthanide complexes for advanced photonic applications  

Microsoft Academic Search

The lanthanide compounds containing unsymmetrical beta-diketone with [2.2]paracyclophane moiety in particular the europium complex with three [1-(4-[2.2]paracyclophanyl)]-3-phenylpropane-1,3-dione and 1,10-phenanthroline has been synthesized for the first time. The optical properties of [2.2]paracyclophane-derived ligands (symmetrical beta-diketones and their respective N-phenylimines) as well as those of the europium complex were studied by UV-visible and luminescence spectroscopy. The diastereomers (racemic chiral, (R*,R*)- and achiral

Lada N. Puntus; Elena V. Sergeeva; Dmitrii Y. Antonov; Konstantin A. Lyssenko; Francois Kajzar

2010-01-01

116

Lanthanide Complexes as a Test for Evidence of Life  

NASA Technical Reports Server (NTRS)

The objective of this research is to advance the understanding of the interaction of lanthanide metals with biological organic molecules and to develop a technique to detect these compounds in the solid state and in situ in Mars and other planetary bodies. The detection of these complexes should provide evidence of life past or present. In addition, detection of the metals alone will provide important information about the geological history of a planetary body. Lanthanides were chosen as our focus of interest because they form very stable complexes with organic molecules in solution and they produce intense luminescence in the ultraviolet and visible spectra. The rare earth complexes available are mostly synthetic for diverse applications in medicine. There is not much work done on the complexes that form in nature. Lanthanides have many applications and they are mined aR over the world, however, since the interest has been only in the elements, the analytical techniques employed destroy any organic ligands that may be present. In order to determine if and which lanthanide complexes form in nature and their concentration, soil samples have been collected from areas rich in soluble lanthanide compounds like phosphates and also rich in vegetation. The soil samples will be analyzed and the lanthanide complexes if present will be isolated and characterized. A spectrometer to detect the lanthanide complexes in situ and in the solid state will be designed. In this workshop, the research approach and its implications will be discussed.

Benavides, Jeannette

1998-01-01

117

Fluid Shifts  

NASA Technical Reports Server (NTRS)

NASA is focusing on long-duration missions on the International Space Station (ISS) and future exploration-class missions beyond low Earth orbit. Visual acuity changes observed after short-duration missions were largely transient, but more than 30% of ISS astronauts experience more profound, chronic changes with objective structural and functional findings such as papilledema and choroidal folds. Globe flattening, optic nerve sheath dilation, and optic nerve tortuosity also are apparent. This pattern is referred to as the visual impairment and intracranial pressure (VIIP) syndrome. VIIP signs and symptoms, as well as postflight lumbar puncture data, suggest that elevated intracranial pressure (ICP) may be associated with the space flight-induced cephalad fluid shifts, but this hypothesis has not been tested. The purpose of this study is to characterize fluid distribution and compartmentalization associated with long-duration space flight, and to correlate these findings with vision changes and other elements of the VIIP syndrome. We also seek to determine whether the magnitude of fluid shifts during space flight, as well as the VIIP-related effects of those shifts, is predicted by the crewmember's pre-flight condition and responses to acute hemodynamic manipulations (such as head-down tilt). Lastly, we will evaluate the patterns of fluid distribution in ISS astronauts during acute reversal of fluid shifts through application of lower body negative pressure (LBNP) interventions to characterize and explain general and individual responses. We will examine a variety of physiologic variables in 10 long-duration ISS crewmembers using the test conditions and timeline presented in the Figure below. Measures include: (1) fluid compartmentalization (total body water by D2O, extracellular fluid by NaBr, intracellular fluid by calculation, plasma volume by CO rebreathe, interstitial fluid by calculation); (2) forehead/eyelids, tibia, calcaneus tissue thickness (by ultrasound); (3) vascular dimensions by ultrasound (jugular veins, cerebral and carotid arteries, vertebral arteries and veins, portal vein); (4) vascular dynamics by MRI (head/neck blood flow, cerebrospinal fluid pulsatility); (5) ocular measures (optical coherence tomography, intraocular pressure, 2-dimensional ultrasound including optic nerve sheath diameter, globe flattening, and retina-choroid thickness, Doppler ultrasound of ophthalmic and retinal arteries, and veins); (6) cardiac variables by ultrasound (inferior vena cava, tricuspid flow and tissue Doppler, pulmonic valve, stroke volume, right heart dimensions and function, four-chamber views); and (7) ICP measures (tympanic membrane displacement, distortion-product otoacoustic emissions, and ICP calculated by MRI). On the ground, acute head-down tilt will induce cephalad fluid shifts, whereas LBNP will oppose these shifts. Controlled Mueller maneuvers will manipulate cardiovascular variables. Through interventions applied before, during, and after flight, we intend to fully evaluate the relationship between fluid shifts and the VIIP syndrome. This study has been selected for flight implementation and is one of the candidate investigations being considered for the one year mission.

Stenger, Michael; Hargens, A.; Dulchavsky, S.; Ebert, D.; Lee, S.; Sargsyan, A.; Martin, D.; Lui, J.; Macias, B.; Arbeille, P.; Platts, S.

2014-01-01

118

Comparison of fat-splitting reagents in the twitchell process  

Microsoft Academic Search

Summary  Commercial petroleum sulfonic acid reagents have been compared with Twitchell reagents, alkylarylsulfonic acids, and sulfoarylstearic\\u000a acids as fat-splitting reagents in the hydrolysis of lard oil, tallow, cotton-seed oil, garbage grease, and inedible grease.\\u000a The best reagents were made from commercial wetting agents of the alkylarylsulfonate type. Sulfoxylylstearic acid, seven petroleum\\u000a sulfonic acids, and four Twitchell reagents followed in decreasing order.

A. J. Stirton; E. M. Hammaker; S. F. Herb; Edward T. Roe

1944-01-01

119

Lanthanide-doped upconverting phosphors for bioassay and therapy  

NASA Astrophysics Data System (ADS)

Lanthanide-doped fluorescent materials have gained increasing attention in recent years due to their unique luminescence properties which have led to their use in wide-ranging fields including those of biological applications. Aside from being used as agents for in vivo imaging, lanthanide-doped fluorescent materials also present many advantages for use in bioassays and therapy. In this review, we summarize the applications of lanthanide-doped up-converting phosphors (UCPs) in protein and gene detection, as well as in photodynamic and gene therapy in recent years, and outline their future potential in biological applications. The current report could serve as a reference for researchers in relevant fields.

Guo, Huichen; Sun, Shiqi

2012-10-01

120

Small particle reagents: development of fluorescent variants.  

PubMed

Small particle reagent (SPR) is a widely used method to develop latent fingerprints on non-porous and wet surfaces. Conventionally, molybdenum disulfide based SPR has been used for the development of latent fingerprints while some SPR based on other materials such as charcoal powder, zinc carbonate and titanium dioxide have been reported. Fluorescent preparations of molybdenum disulfide based SPR have also been reported. In the present work, a number of SPR based on zinc carbonate have been developed in combination with various fluorescent dyes to develop latent fingerprints on a number of non-porous surfaces. The quality of the developed fingerprints have been evaluated and found to be reproducible. The shelf life of the reagents developed is found to be acceptable for case work purposes. The relationship between the immersion period of the substrate bearing the latent fingerprints and reagent has also been examined. PMID:18953802

Jasuja, O P; Singh, Gagan Deep; Sodhi, G S

2008-09-01

121

Pulsed photothermal spectroscopy applied to lanthanide and actinide speciation.  

National Technical Information Service (NTIS)

Several key elements important for the application of laser-based photothermal spectroscopies to the study of the complexation chemistry of lanthanides and actinides in solution have been demonstrated. The sensitivity of f-f electronic transition energies...

J. M. Berg D. E. Morris D. L. Clark C. D. Tait W. H. Woodruff

1991-01-01

122

Electromotive force measurement of lanthanides in liquid lead  

Microsoft Academic Search

The activity coefficients of La and Pr dissolved in liquid Pb were determined by the electromotive force (EMF) measurement of the galvanic cell, Ln (solid)|LiCl–KCl–LnCl3|Ln–Pb (solution). The temperature dependence of the activity coefficients of lanthanides is expressed by log ? = a + b\\/T, where a and b are the constants. The excess enthalpy and entropy of lanthanides in the melt were obtained and compared

Takehiro Maruyama; Kenji Uda; Kimikazu Moritani; Takayuki Sasaki; Hirotake Moriyama

2012-01-01

123

Synthesis and luminescence of lanthanide ions in nanoscale insulating hosts  

Microsoft Academic Search

This review summarizes recent work in nanostructured insulating materials that contain optically active lanthanide ions. These materials find applications in lasers, optical amplifiers, and optical-display phosphors. This review concentrates on the synthesis and luminescence spectroscopy of lanthanide-containing nanostructured particles, films, and composites. Spectroscopic studies range from basic luminescence spectroscopy and quantum efficiency measurements to high-resolution spectroscopic studies that investigate the

Brian M. Tissue

1998-01-01

124

A structural study of ternary lanthanide orthoscandate perovskites  

NASA Astrophysics Data System (ADS)

Ternary lanthanide scandates ( Ln=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, and Ho) have been synthesized at ambient pressure. Their structure has been investigated at room temperature by Rietveld analysis of powder X-ray diffraction data. The Ln-scandates are orthorhombic perovskites, adopting space group Pbnm (? 62), a? b??2 ap, c?2 ap, Z=4. Heavy lanthanides (Er-Lu), and Y do not form perovskites at ambient conditions. Compositionally driven phase transitions were not observed. The unit-cell parameters decrease with increasing ScO 6 octahedron rotation and atomic number of the Ln cation. In common with lanthanide orthoferrites, the uniform structural evolution is interrupted at the middle-heavy part of the lanthanide sequence. This is probably due to an interplay between: (i) enlargement of the ScO 6 octahedra relative to BO 6 in other perovskites (e.g., FeO 6 in GdFeO 3); (ii) reduction in size of the first coordination sphere of Ln3+ coincident with the lanthanide contraction; (iii) coincident expansion of the second coordination sphere due to screening effects of O I1 on O I2, and entry of Sc to the lanthanide coordination sphere; (iv) complex mixing between oxygen and lanthanide lanthanide f- and scandium d-orbitals. In the series studied, Ln3+ are in eight-fold coordination (tetragonal antiprism), and are considerably displaced from the center of the LnO 8 polyhedron along [001]. Evolution of the crystallochemical characteristics through the Ln orthoscandate series is complex due to both the antipathetic distortions of A- and B-site coordination polyhedra and interaction of the orbitals of oxygen, Ln and Sc. Empirically obtained limits of Goldschmidt and observed viiito tolerance factors for ternary LnBO 3 compounds adopting the Pbnm structure are 0.795 and 0.841, respectively.

Liferovich, Ruslan P.; Mitchell, Roger H.

2004-06-01

125

DEGRADATION OF MTBE INTERMEDIATES USING FENTON'S REAGENT  

EPA Science Inventory

In a previous study, the chemical oxidation of MTBE at low concentrations in water using the Fenton's reagent (FR) was investigated. At certain reaction conditions the process achieved 99.99% degradation of MTBE but it did not result in complete MTBE mineralization. In the pres...

126

Aqueous Relaxation Reagents in Nitrogen-15 NMR.  

National Technical Information Service (NTIS)

Electron-nuclear relaxation times T(1)supe's for 15N and 13C in natural abundance are measured for a series of amines in aqueous solution using Gd(III) complexes of a series of polyaminocarboxylate ligands as paramagnetic relaxation reagents (PARRs). The ...

J. J. Dechter G. C. Levy

1979-01-01

127

Reactions of difluorocarbene with organozinc reagents.  

PubMed

Reactions of difluorocarbene with benzyl and alkylzinc halides leading to fluorinated organozinc species have been described. The generated ?-difluorinated organozinc reagents are reasonably stable in solution and can be quenched with external electrophiles (iodine, bromine, proton), affording compounds containing the CF(2) fragment. PMID:23368906

Levin, Vitalij V; Zemtsov, Artem A; Struchkova, Marina I; Dilman, Alexander D

2013-02-15

128

AQUEOUS RELAXATION REAGENTS IN NITROGEN-15 NMR  

EPA Science Inventory

Electron-nuclear relaxation times T(1)supe's for 15N and 13C in natural abundance are measured for a series of amines in aqueous solution using Gd(III) complexes of a series of polyaminocarboxylate ligands as paramagnetic relaxation reagents (PARRs). The PARRs are classified by t...

129

Remarks on preparation of indandione detection reagents  

NASA Technical Reports Server (NTRS)

A modified Claisen condensation with sliced sodium at a higher temperature was recommended for the production of ungranulated charcoal. A new ninhydrin production method by oxidation of benzaldiketohydrinden using available reagents was tried and was unsuccessful. Triketohydrinden was obtained by boiling ninhydrin in acetic acid anhydrides.

Stepan, J.; Kral, V.

1985-01-01

130

Enantioselective outer-sphere complexation of lanthanide(III) tris (pyridine-2,6-dicarboxylate) chelates with vitamin B 12 derivatives. An NMR and CD study  

Microsoft Academic Search

The binding of three corrinoids, cyanocobalarnin (vitamin B12, CNCbl), aquacobalamin (vitamin B12a, H2OCbl+) and dicyanocobinamide ((CN)2Cbi), collectively denoted by Q, to the ?- and ?-enantiomer of Ln(DPA)33? complexes (Ln=lanthanide, DPA=2,6-pyridine dicarboxylate) in aqueous solution at room temperature is investigated by NMR and Circular Dichroism (CD) spectroscopy. Tb(DPA)33? induces shifts of the 1H-NMR resonances of Q. A formula, describing the dipolar

Stefan C. J. Meskers; Harry P. J. M. Dekkers

1999-01-01

131

Responsive lanthanide coordination polymer for hydrogen sulfide.  

PubMed

Metal organic coordination polymers have received great attention because of their flexible compositions and architecture. Here, we report the design and synthesis of a responsive lanthanide coordination polymer (LCP) for hydrogen sulfide (H2S), utilizing self-assembling of biomolecule nucleotide with luminescent terbium ion (Tb(3+)) and sensitizing silver ion (Ag(+)) in aqueous solution. LCP is highly fluorescent due to the inclusion of Ag(+) ions, which sensitized the fluorescence of Tb(3+) ions. H2S can strongly quench the fluorescence of LCP through its high affinity for Ag(+) ions. Such configurated LCP material from initial building blocks showed high sensitivity and selectivity for H2S and was applied to the determination of H2S in human serum. LCP with Tb(3+) ions also has a long fluorescence lifetime, which allows for time-resolved fluorescence assays, possessing particular advantages to probing H2S in biological systems with autofluorescence. PMID:24191713

Liu, Baoxia; Chen, Yang

2013-11-19

132

Covalency in Actinide and Lanthanide Hexachloride Anions  

NASA Astrophysics Data System (ADS)

Whether actinide atoms form covalent or ionic bonds is still a matter of debate after many years of study and it remains a challenge for experimentalists and theoreticians. From the experimental side, synchrotron-based ligand K-edge X-ray absorption spectroscopy appears as a promising technique for probing this issue. From the theoretical perspective, quantum chemical simulations should be able to add on a first principle understanding. To tackle this problem, we have applied these techniques on a series of octahedral uranium and lanthanide chloride salts, MCl6^n- (M= U, Ce, Pr) in various oxidation states (n=1, 2, 3). We will show hybrid density functional theory calculations that give evidence of the covalent nature of the M-Cl bond in a quantitative manner. This covalency was found to increase for higher oxidation states.

Yang, Ping; Batista, Enrique; Martin, Richard; Carlson, Christin; Clark, David; Conradson, Steven; Schwarz, Daniel; Wilkerson, Marinne

2007-03-01

133

Luminescent lanthanide (Eu3+, Tb3+) hybrids with 4-vinylbenzeneboronic acid functionalized Si-O bridges and beta-diketones.  

PubMed

4-Vinylphenylboronic acid ligand (VPBA) is functionalized with two crosslinking reagents (3-(triethoxysilyl)-propylisocyanate [TEPIC] and 3-(trimethoxysilyl) propyl methacrylate [TMPMA]) to achieve the two special molecular bridge VPBA-TEPIC and VPBA-TMPMA. Meanwhile, beta-diketone ligands (2-thenoyltrifluoroacetone [TTA], acetyl acetone [ACAC]) as the second ligands play the role of the main energy donor, which absorb abundant energy in ultraviolet-visible extent and then transfer the energy to the corresponding lanthanide ions (Eu(3+), Tb(3+)) to sensitize their emission of them. Eight binary and ternary Eu(3+), Tb(3+) hybrids with VPBA-TEPIC (VPBA-TMPMA) and TTA (ACAC) have been constructed, whose photoluminescence properties are studied in depth and suggest that the ternary hybrids show the favorable characteristic luminescent properties (longer lifetime and higher quantum efficiency). PMID:21466557

Yan, Bing; Guo, Min; Qiao, Xiao-Fei

2011-01-01

134

Luminescence of Lanthanide-Dimethyl Sulfoxide Compound Solutions  

SciTech Connect

Dimethyl sulfoxide (DMSO) has the ability to penetrate living tissues without causing significant damage. Of foremost importance to our understanding of the possible functions of DMSO in biological systems is its ability to replace some of the water molecules associated with the cellular constituents, or to affect the structure of the omnipresent water. Luminescence probes have been widely used for biological studies such as labeling, imaging and detection. Luminescence probes formed in DMSO may find new applications. Here, luminescence compounds formed by refluxing lanthanide nitrates of Ce, La, Tb, Yb, Nd, Gd and Eu in DMSO are reported and their luminescence properties investigated. Based on their luminescence spectral properties, the compounds can be classified into four classes. For compounds-I with Yb, Ce, and La, the excitation and emission spectra are very broad and their excitation or emission peaks are shifted to longer wavelengths when the monitored emission or excitation wavelength is longer . For compounds-II with Gd and Nd, both the excitation and emission spectra are very broad but their emission wavelengths change little at different excitation wavelengths. For Tb-DMSO as compound-III, both the typical emissions from the f - f transitions of Tb3+ and a broad emission at 445 nm are observed. At low temperatures of reaction, the f - f emissions are dominant, while at high temperatures such as 180 oC of reaction, the broad emission at 445 nm is dominant. For compound-IV with Eu-DMSO compounds, the dominant emissions are from the f - f transitions of Eu3+ and only a weak broad emission is observed, which is likely from the d - f transition of Eu2+ rather than from the metal to ligand charge transfer states.

Yao, Mingzhen; Li, Yuebin; Hossu, Marius; Joly, Alan G.; Liu, Zhongxin; Liu, Zuli; Chen, Wei

2011-08-04

135

Supramolecular recognition of heteropairs of lanthanide ions: a step toward self-assembled bifunctional probes.  

PubMed

Three unsymmetrical ditopic hexadentate ligands coded for the recognition of trivalent lanthanide ions have been synthesized, L(AB), L(AC), and L(BC), where A represents a benzimidazole-pyridine-benzimidazole coordination unit, B a benzimidazole-pyridine-carboxamide one, and C a benzimidazole-pyridine-carboxylic acid moiety. Under stoichiometric 2:3 (Ln:L) conditions, these ligands self-assemble with lanthanide ions to yield triple-stranded bimetallic helicates having a sizable stability in acetonitrile: log beta(23) values for Eu are equal to 23.9 +/- 0.5 (L(AB)), 23.3 +/- 0.7 (deprotonated L(AC)), and 29.8 +/- 0.5 (deprotonated L(BC)). The crystal structure of the EuEu helicate with L(AB) shows 9-coordinate metal ions and an HHH (H stands for head) configuration of the helically wrapped ligand strands. In the presence of equimolar quantities of Ln and Ln' ions, L(AB) displays a remarkable predisposition to form HHH-heterobimetallic edifices, as proved both in the solid state by the crystal structures of the LaEu, LaTb, PrEr, and PrLu helicates and in solution by NMR spectroscopy. In all cases, the benzimidazole-pyridine-carboxamide units of the three ligands are bound to the smaller lanthanide ion, a fact further ascertained by high-resolution luminescence data on LaEu and by (1)H NMR. Analysis of the lanthanide-induced (1)H NMR shifts and of the spin-lattice relaxation times of the [LnLu(L(AB))(3)](6+) series (Ln = Ce, Pr, Nd, Sm, Eu) demonstrates the isostructural nature of the complexes in solution and that the crystal structure of LaTb is a good model for the solution structure. The selectivity of L(AB) for heteropairs of Ln(III) ions increases with increasing difference in ionic radius, resulting in 70% of the heterobimetallic species for deltar(i) = 0.1 A and up to 90% for LaLu (deltar(i) = 0.18 A), and corresponding to delta(deltaG) in the range 3-10 kJ.mol(-)(1). The origins of this stabilization are discussed in terms of the donor properties of the coordinating units and of the preferential formation of HHH isomers. PMID:14731013

André, Nicolas; Jensen, Thomas B; Scopelliti, Rosario; Imbert, Daniel; Elhabiri, Mourad; Hopfgartner, Gérard; Piguet, Claude; Bünzli, Jean-Claude G

2004-01-26

136

The Grignard Reagent: Preparation, Structure, and Some Reactions.  

ERIC Educational Resources Information Center

The Grignard reagent used in the laboratory synthesis of organic compounds is the product resulting from the reaction of an alkyl or aryl halide with elemental magnesium. Describes the structure, formation, and some reactions of the reagent. (YP)

Orchin, Milton

1989-01-01

137

21 CFR 866.3460 - Rabiesvirus immuno-fluorescent reagents.  

Code of Federal Regulations, 2010 CFR

... false Rabiesvirus immuno-fluorescent reagents. 866.3460 Section...3460 Rabiesvirus immuno-fluorescent reagents. (a) Identification...rabiesvirus antisera conjugated with a fluorescent dye used to identify...

2009-04-01

138

21 CFR 866.3460 - Rabiesvirus immuno-fluorescent reagents.  

Code of Federal Regulations, 2010 CFR

... false Rabiesvirus immuno-fluorescent reagents. 866.3460 Section...3460 Rabiesvirus immuno-fluorescent reagents. (a) Identification...rabiesvirus antisera conjugated with a fluorescent dye used to identify...

2010-04-01

139

21 CFR 606.65 - Supplies and reagents.  

Code of Federal Regulations, 2011 CFR

...clean and free of surface solids and other contaminants. (b) Each blood collecting container and its satellite container...Do. Antibody screening and reverse grouping cells Do. Hepatitis test reagents Each run. Syphilis serology reagents...

2011-04-01

140

21 CFR 866.3165 - Cryptococcus neoformans serological reagents.  

Code of Federal Regulations, 2013 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3165 Cryptococcus neoformans serological reagents....

2013-04-01

141

21 CFR 866.3380 - Mumps virus serological reagents.  

Code of Federal Regulations, 2013 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3380 Mumps virus serological reagents. (a)...

2013-04-01

142

21 CFR 866.3930 - Vibrio cholerae serological reagents.  

Code of Federal Regulations, 2013 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3930 Vibrio cholerae serological reagents. (a)...

2013-04-01

143

21 CFR 866.3700 - Staphylococcus aureus serological reagents.  

Code of Federal Regulations, 2013 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3700 Staphylococcus aureus serological reagents. (a)...

2013-04-01

144

21 CFR 866.3200 - Echinococcus spp. serological reagents.  

Code of Federal Regulations, 2013 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3200 Echinococcus spp. serological reagents. (a)...

2013-04-01

145

21 CFR 866.3470 - Reovirus serological reagents.  

Code of Federal Regulations, 2013 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3470 Reovirus serological reagents. (a)...

2013-04-01

146

21 CFR 866.3600 - Schistosoma spp. serological reagents.  

Code of Federal Regulations, 2013 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3600 Schistosoma spp. serological reagents. (a)...

2013-04-01

147

21 CFR 866.3780 - Toxoplasma gondii serological reagents.  

Code of Federal Regulations, 2013 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3780 Toxoplasma gondii serological reagents. (a)...

2013-04-01

148

21 CFR 866.3630 - Serratia spp. serological reagents.  

Code of Federal Regulations, 2013 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3630 Serratia spp. serological reagents. (a)...

2013-04-01

149

21 CFR 866.3870 - Trypanosoma spp. serological reagents.  

Code of Federal Regulations, 2013 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3870 Trypanosoma spp. serological reagents. (a)...

2013-04-01

150

21 CFR 866.3500 - Rickettsia serological reagents.  

Code of Federal Regulations, 2013 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3500 Rickettsia serological reagents. (a)...

2013-04-01

151

21 CFR 866.3330 - Influenza virus serological reagents.  

Code of Federal Regulations, 2013 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3330 Influenza virus serological reagents. (a)...

2013-04-01

152

21 CFR 866.3940 - West Nile virus serological reagents.  

Code of Federal Regulations, 2013 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3940 West Nile virus serological reagents. (a)...

2013-04-01

153

21 CFR 866.3250 - Erysipelothrix rhusiopathiae serological reagents.  

Code of Federal Regulations, 2013 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3250 Erysipelothrix rhusiopathiae serological reagents....

2013-04-01

154

21 CFR 866.3680 - Sporothrix schenckii serological reagents.  

Code of Federal Regulations, 2013 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3680 Sporothrix schenckii serological reagents. (a)...

2013-04-01

155

21 CFR 866.3375 - Mycoplasma spp. serological reagents.  

Code of Federal Regulations, 2013 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3375 Mycoplasma spp. serological reagents. (a)...

2013-04-01

156

21 CFR 866.3270 - Flavobacterium spp. serological reagents.  

Code of Federal Regulations, 2013 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3270 Flavobacterium spp. serological reagents. (a)...

2013-04-01

157

21 CFR 866.3205 - Echovirus serological reagents.  

Code of Federal Regulations, 2013 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3205 Echovirus serological reagents. (a)...

2013-04-01

158

21 CFR 866.3550 - Salmonella spp. serological reagents.  

Code of Federal Regulations, 2013 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3550 Salmonella spp. serological reagents. (a)...

2013-04-01

159

21 CFR 866.3020 - Adenovirus serological reagents.  

Code of Federal Regulations, 2013 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3020 Adenovirus serological reagents. (a)...

2013-04-01

160

21 CFR 866.3320 - Histoplasma capsulatum serological reagents.  

Code of Federal Regulations, 2013 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3320 Histoplasma capsulatum serological reagents....

2013-04-01

161

21 CFR 866.3355 - Listeria spp. serological reagents.  

Code of Federal Regulations, 2013 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3355 Listeria spp. serological reagents. (a)...

2013-04-01

162

21 CFR 866.3280 - Francisella tularensis serological reagents.  

Code of Federal Regulations, 2013 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3280 Francisella tularensis serological reagents....

2013-04-01

163

Seebach's Conjunctive Reagent Enables Double Cyclizations  

PubMed Central

When ketones flanked on both sides by nucleophilic atoms react with Seebach’s nitropropenyl pivaloate reagent, direct couplings take place to give two new ring systems and three bonds. cis-Ring fusions are observed in unions leading to 5,5-, 5,6-, and 6,6-bicycles. Densely functionalized and rigid frameworks may be rapidly formed by the chemistry described herein.

Chandler, Brent D.; Roland, Jason T.; Li, Yukai; Sorensen, Erik J.

2011-01-01

164

Pyrocatecholsulphonphthalein complexan as an analytical reagent.  

PubMed

Pyrocatecholsulphonphthalein complexan (PSC) has been synthesized from Pyrocatechol Violet (PV), iminodiacetic acid and formaldehyde by Mannich condensation. Its acid dissociation equilibria have been studied potentiometrically. Some characteristic properties of Xylenol Orange (XO) and PV are found in PSC, which is slightly superior to XO and PV in sensitivity as a chromogenic reagent for bismuth. The spectrophotometric characteristics of some metal ion-PSC complexes are reported. PMID:18963736

Yu, R Q; Zhang, Z Q; Zhang, Z H

1984-12-01

165

Treatment of textile wastewater by Fenton's reagent  

Microsoft Academic Search

Treatment of textile wastewaters from a dyeing and finishing mill by Fenton's reagent is investigated. The experimental results are assessed in terms of COD and color (turbidity) reductions to determine the treatment efficiency of the Fenton's process. Operating variables, such as the pH, amounts of H2O2 and FeSO4, time of Fenton's treatment and amounts of polyaluminum chloride (PAC) and polymer,

S. H. Lin; C. F. Peng

1995-01-01

166

21 CFR 58.83 - Reagents and solutions.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Reagents and solutions. 58.83 Section 58.83 Food and Drugs...Facilities Operation § 58.83 Reagents and solutions. All reagents and solutions in the laboratory areas shall be...

2013-04-01

167

Development of new biotin\\/streptavidin reagents for pretargeting  

Microsoft Academic Search

The high affinity of biotin for streptavidin has made this pair of molecules very useful for in vivo applications. To optimize reagents for one potential in vivo application, antibody-based pretargeting of cancer, we have prepared a number of new biotin and streptavidin derivatives. The derivatives developed include new radiolabeled biotin reagents, new protein biotinylation reagents, and new biotin multimers for

D Scott Wilbur; Pradip M Pathare; Donald K Hamlin; Patrick S Stayton; Richard To; Lisa A Klumb; Kent R Buhler; Robert L Vessella

1999-01-01

168

21 CFR 660.30 - Reagent Red Blood Cells.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2010-04-01 true Reagent Red Blood Cells. 660.30 Section 660.30 Food...DIAGNOSTIC SUBSTANCES FOR LABORATORY TESTS Reagent Red Blood Cells § 660.30 Reagent Red Blood Cells. (a) Proper name and...

2011-04-01

169

21 CFR 660.30 - Reagent Red Blood Cells.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Reagent Red Blood Cells. 660.30 Section 660.30 Food...DIAGNOSTIC SUBSTANCES FOR LABORATORY TESTS Reagent Red Blood Cells § 660.30 Reagent Red Blood Cells. (a) Proper name and...

2009-04-01

170

21 CFR 660.30 - Reagent Red Blood Cells.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Reagent Red Blood Cells. 660.30 Section 660.30 Food...DIAGNOSTIC SUBSTANCES FOR LABORATORY TESTS Reagent Red Blood Cells § 660.30 Reagent Red Blood Cells. (a) Proper name and...

2010-04-01

171

First observation of enhanced luminescence from single lanthanide chelates on silver nanorods.  

PubMed

We used near-field interactions with a silver nanorod (AgNR) to greatly enhance luminescence of a lanthanide (Ln) chelate. The enhancement factor was 280-fold, making single lanthanide luminescence detectable. This is also the first observation on single molecule detection (SMD) of a lanthanide dye. PMID:25004953

Zhang, Jian; Ray, Krishanu; Fu, Yi; Lakowicz, Joseph R

2014-07-22

172

Lanthanides in metallic nuclear fuels: Their behavior and methods for their control  

Microsoft Academic Search

The thermodynamic and experimental basis is given for using dopant additives to bind lanthanides as intermetallic compounds in metallic nuclear fuels. Lanthanide fission products are a major factor in limiting the lifetime of the fuel, because they migrate to the fuel slug peripheral surface where they participate in fuel-cladding chemical interactions (FCCI) with the D9 or HT9 steel cladding. Lanthanide

Robert D. Mariani; Douglas L. Porter; T. P. O’Holleran; Steven L. Hayes; J. Rory Kennedy

2011-01-01

173

Containment of Spray Reagents in TLC Spot Detection  

NASA Astrophysics Data System (ADS)

A recent suggestion to visualize spots on thin layer plates by applying phosphomolybdic acid reagent with a cotton ball (1) may not be suitable for all visualization reagents especially concentrated sulfuric acid. If spraying a reagent with a power pac type device is preferred for this or some other reason, we suggest spraying the reagent inside of a twist tie-sealed, clear-plastic kitchen garbage bag. In this way, spray reagents are completely contained obviating the need for spraying the plates in a fume hood, and cleanup is simple. Literature Cited 1. Lee, A. W. M.; Zengpei, Z. J. Chem. Educ., 1996, 73, 358.

Krause, Josef G.

1996-10-01

174

Shelf-stable electrophilic trifluoromethylating reagents: A brief historical perspective  

PubMed Central

Summary Since the discovery by Yagupolskii and co-workers that S-trifluoromethyl diarylsulfonium salts are effective for the trifluoromethylation of thiophenolates, the design and synthesis of electrophilic trifluoromethylating reagents have been extensively researched in both academia and industry, due to the significant unique features that trifluoromethylated compounds have in pharmaceuticals, agricultural chemicals, and functional materials. Several effective reagents have been developed by the groups of Yagupolskii, Umemoto, Shreeve, Adachi, Magnier, Togni and Shibata. Due to the high stability and reactivity of these reagents, a series of Umemoto reagents, Togni reagent and Shibata reagent are now commercially available. In this review, we wish to briefly provide a historical perspective of the development of so-called “shelf-stable electrophilic trifluoromethylating reagents”, although this field is in constant development.

Matsnev, Andrej

2010-01-01

175

Purification of lanthanides for large neutrino detectors: Thorium removal from gadolinium chloride  

NASA Astrophysics Data System (ADS)

Metal-loaded liquid scintillators are the detectors of choice for various neutrino experiments. Procedures have been developed to transfer metals into organic liquids by solvent extraction or direct dissolution of a metallic compound. Traces of natural radioactivity introduced into the scintillator with the metal may produce undesirable backgrounds. Measurements using a 229Th tracer indicate that the inclusion of a pH-controlled partial hydrolysis and filtration prior to the preparation of a gadolinium-loading compound can reduce thorium by a factor of ˜100. This "self-scavenging" procedure has the advantage that it uses only reagents encountered in the production process. Addition of non-elemental scavengers such as iron, or the use of solvent extraction or ion exchange procedures can be avoided. It also improves the optical transmission in the blue region by removing traces of iron. This purification method has potential applications to the large-scale production of other metal-loaded liquid scintillators and for the removal of traces of thorium in the industrial production of lanthanides.

Yeh, M.; Cumming, J. B.; Hans, S.; Hahn, R. L.

2010-06-01

176

Purificaiton of Lanthanides for Large Neutrino Detectors: Thorium Removal from Gadolinium Chloride  

SciTech Connect

Metal-loaded liquid scintillators are the detectors of choice for various neutrino experiments. Procedures have been developed to transfer metals into organic liquids by solvent extraction or direct dissolution of a metallic compound. Traces of natural radioactivity introduced into the scintillator with the metal may produce undesirable backgrounds. Measurements using a {sup 229}Th tracer indicate that the inclusion of a pH-controlled partial hydrolysis and filtration prior to the preparation of a gadolinium-loading compound can reduce thorium by a factor of {approx}100. This 'self-scavenging' procedure has the advantage that it uses only reagents encountered in the production process. Addition of non-elemental scavengers such as iron, or the use of solvent extraction or ion exchange procedures can be avoided. It also improves the optical transmission in the blue region by removing traces of iron. This purification method has potential applications to the large-scale production of other metal-loaded liquid scintillators and for the removal of traces of thorium in the industrial production of lanthanides.

Yeh, M.; Cumming, J.B.; Hans, S.; Hahn, R.L.

2010-06-01

177

21 CFR 866.3720 - Streptococcus spp. exo-enzyme reagents.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Streptococcus spp. exo-enzyme reagents. ...Serological Reagents § 866.3720 Streptococcus spp. exo-enzyme reagents. (a) Identification. Streptococcus spp. exoenzyme reagents...

2009-04-01

178

21 CFR 866.3720 - Streptococcus spp. exo-enzyme reagents.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Streptococcus spp. exo-enzyme reagents. ...Serological Reagents § 866.3720 Streptococcus spp. exo-enzyme reagents. (a) Identification. Streptococcus spp. exoenzyme reagents...

2010-04-01

179

21 CFR 866.3235 - Epstein-Barr virus serological reagents.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 false Epstein-Barr virus serological reagents. 866.3235 Section...Reagents § 866.3235 Epstein-Barr virus serological reagents. (a) Identification. Epstein-Barr virus serological reagents are devices...

2013-04-01

180

Nature of the electronic band gap in lanthanide oxides  

NASA Astrophysics Data System (ADS)

Accurate electronic structures of the technologically important lanthanide/rare-earth sesquioxides (Ln2O3, with Ln=La,⋯,Lu) and CeO2 have been calculated using hybrid density functionals HSE03, HSE06, and screened exchange (sX-LDA). We find that these density functional methods describe the strongly correlated Ln f electrons as well as the recent G0W0@LDA+U results, generally yielding the correct band gaps and trends across the Ln period. For HSE, the band gap between O 2p states and lanthanide 5d states is nearly independent of the lanthanide, while the minimum gap varies as filled or empty Ln 4f states come into this gap. sX-LDA predicts the unoccupied 4f levels at higher energies, which leads to a better agreement with experiments for Sm2O3, Eu2O3, and Yb2O3.

Gillen, Roland; Clark, Stewart J.; Robertson, John

2013-03-01

181

Ultrasensitive DNAzyme beacon for lanthanides and metal speciation.  

PubMed

Metal-ion detection and speciation analysis is crucial for environmental monitoring. Despite the importance of lanthanides, few sensors are available for their detection. DNAzymes have been previously used to detect divalent metals, while no analytical work was carried out for trivalent and tetravalent ions. Herein, in vitro selection was performed using a Ce(4+) salt as the target metal, and a new DNAzyme (named Ce13) with a bulged hairpin structure was isolated and characterized. Interestingly, Ce13 has almost no activity with Ce(4+) but is highly active with all trivalent lanthanides and Y(3+), serving as a general probe for rare earth metals (omitting Sc). A DNAzyme beacon was engineered detecting down to 1.7 nM Ce(3+) (240 parts per trillion), and other lanthanides showed similar sensitivity. The feasibility of metal speciation analysis was demonstrated by measuring the reduction of Ce(4+) to Ce(3+). PMID:24383540

Huang, Po-Jung Jimmy; Lin, Jenny; Cao, Jing; Vazin, Mahsa; Liu, Juewen

2014-02-01

182

New quinolone-based thiol-reactive lanthanide luminescent probes  

PubMed Central

Luminescent lanthanide ion complexes are distinguished by unique light emitting properties that enable both highly sensitive detection of lanthanide labels attached to biomolecules and contrast imaging of various micro objects (cells, nanoparticles, etc.). Previously, we synthesized amine-reactive cs124-based luminescent lanthanide chelates with improved brightness and metal retention. Here we report the synthesis of new thiol-reactive derivatives of the same compounds including bromoacetamido-, and maleimido- forms of cs124 and cs124CF3 fluorophores. Maleimido-compounds displayed exceptional reactivity instantaneously coupling to thiols at physiological conditions at micromolar probes concentrations. Surprisingly, they displayed strong quenching by adjacent maleimido-group, which was completely eliminated after reaction with thiols, thereby enabling their simple detection by monitoring the light emission of the reaction mixture. This reaction can be used for hyper-sensitive determination of biologically important sulphydryl compounds (e.g. glutathione, co-enzyme A, etc.) in time-resolved mode.

Wirpsza, Laura; Krasnoperov, Lev; Mustaev, Arkady

2013-01-01

183

[Influence of reagent evaporation on other laboratory reagents and appropriate countermeasures].  

PubMed

When the automated analyzer was first introduced, abnormally high values of urine creatinine and abnormally low values of serum creatinine were seen. It was shown that evaporation of the reducing agent stabilizer(sulfurous acid), which is present in the serum iron measurement kit, was occurring and that the observed low values of serum creatinine were due to consumption of hydrogen peroxide by gasifying sulfurous acid. After the cause was elucidated, the abnormal lowering of creatinine values was prevented. This experience demonstrates that care must be exercised when introducing new analytical method in clinical laboratories because evaporation of reagents can influence in other reagent systems. PMID:14560654

Sato, Toshimi; Tani, Kenji; Yoshimura, Hajime; Sakurabayashi, Ikunosuke

2003-09-01

184

Magnetic field alignable domains in phospholipid vesicle membranes containing lanthanides.  

PubMed

Magnetic fields were applied as a structuring force on phospholipid-based vesicular systems, using paramagnetic lanthanide ions as magnetic handles anchored to the vesicle membrane. Different vesicle formulations were investigated using small angle neutron scattering (SANS) in a magnetic field of up to 8 T, cryo-transmission electron microscopy (cryo-TEM), (31)P NMR spectroscopy, dynamic light scattering (DLS), and permeability measurements with a fluorescent water-soluble marker (calcein). The investigated vesicle formulations consisted usually of 80 mol % of the phospholipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and 20 mol % of a chelator lipid (DMPE-DTPA; 1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine-diethylenetriaminepentaacetate) with complexed lanthanide ions (Tm(3+), Dy(3+), or La(3+)), and the total lipid concentration was 15 mM. Vesicles containing the paramagnetic lanthanide Tm(3+) or Dy(3+) exhibited a temperature-dependent response to magnetic fields, which can be explained by considering the formation of lipid domains, which upon reaching a critical size become alignable in a magnetic field. The features of this "magnetic field alignable domain model" are as follows: with decreasing temperature (from 30 to 2.5 degrees C) solid domains, consisting mainly of the higher melting phospholipid (DMPE-DTPA.lanthanide), begin to form and grow in size. The domains assemble the large magnetic moments conferred by the lanthanides and orient in magnetic fields. The direction of alignment depends on the type of lanthanide used. The domains orient with their normal parallel to the magnetic field with thulium (Tm(3+)) and perpendicular with dysprosium (Dy(3+)). No magnetic field alignable domains were observed if DMPE-DTPA is replaced either by POPE-DTPA (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine-diethylenetriamine-pentaacetate) or by DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine). PMID:20017528

Beck, Paul; Liebi, Marianne; Kohlbrecher, Joachim; Ishikawa, Takashi; Rüegger, Heinz; Zepik, Helmut; Fischer, Peter; Walde, Peter; Windhab, Erich

2010-01-14

185

Chiral cis-octahedral Grignard reagents  

Microsoft Academic Search

Three chiral cis-octahedral Grignard reagents have been synthesized and structurally characterized by X-ray diffraction methods. Crystals of cis-[(n-Pr)MgBr(dme)2] (1), cis-[(i-Pr)MgBr(dme)2] (2) and cis-[(allyl)MgBr(dme)2] (3) were prepared from neat 1,2-dimethoxyethane (DME) and are all racemic. Synthesis and structural characterization of trans-[MgBr2(tmeda)2] (4) and cis-[MgBr2(dme)2] (5) indicated that bidentate tertiary amino ligands may be less well suited for the preparation of cis-octahedral

Marcus Vestergren; Johan Eriksson; Mikael Håkansson

2003-01-01

186

Facile Oxidative Rearrangements Using Hypervalent Iodine Reagents  

PubMed Central

Aromatic substituents migrate in a novel oxidative cyclization mediated by iodine(III) reagents. 4-Arylbut-3-enoic acids are cyclized and rearranged to 4-arylfuran-2(5H)-ones by hypervalent iodine compounds in good to excellent yields under mild reaction conditions. Other ring sizes are also accessible. The mechanism of the reaction is described in detail, and calculations highlight the cationic nature of the intermediates in the rearrangement. The fast access to heavily substituted furanones is used for the synthesis of biologically active derivatives.

Singh, Fateh V; Rehbein, Julia; Wirth, Thomas

2012-01-01

187

Method for providing oxygen ion vacancies in lanthanide oxides  

DOEpatents

A method for desulfurization of fuel gases resulting from the incomplete combustion of sulfur containing hydrocarbons whereby the gases are treated with lanthanide oxides containing large numbers of oxygen-ion vacancies providing ionic porosity which enhances the ability of the lanthanide oxides to react more rapidly and completely with the sulfur in the fuel gases whereby the sulfur in such gases is reduced to low levels suitable for fuels for firing into boilers of power plants generating electricity with steam turbine driven generators, gas turbines, fuel cells and precursors for liquid fuels such as methanol and the like.

Kay, D. Alan R. (4305 Lakeshore Rd., Burlington, CA); Wilson, William G. (820 Harden Dr., Pittsburgh, PA 15229)

1989-12-05

188

Plasma mass filtering for separation of actinides from lanthanides  

NASA Astrophysics Data System (ADS)

Separating lanthanides from actinides is a key process in reprocessing nuclear spent fuel. Plasma mass filters, which operate on dissociated elements, offer conceptual advantages for such a task as compared with conventional chemical methods. The capabilities of a specific plasma mass filter concept, called the magnetic centrifugal mass filter, are analyzed within this particular context. Numerical simulations indicate separation of americium ions from a mixture of lanthanides ions for plasma densities of the order of 1012 cm?3, and ion temperatures of about 10 eV. In light of collision considerations, separating small fractions of heavy elements from a larger volume of lighter ones is shown to enhance the separation capabilities.

Gueroult, R.; Fisch, N. J.

2014-06-01

189

Gibbs energies of formation of hydroxides of lanthanides and yttrium  

NASA Astrophysics Data System (ADS)

The pH values of the formation of hydrates in solutions of yttrium(III), cerium(III), samarium(III), europium(III), erbium(III), and ytterbium(III) were determined by conductometric titration. The solubility products and Gibbs energies of formation for hydroxides for the elements listed were calculated. The average Gibbs energy of dissolution for lanthanide hydroxides was found to be approximately 149.83 ± 0.90 kJ/mol. The Gibbs energies of formation for hydroxides of the remaining lanthanides were assessed on this basis.

Chirkst, D. E.; Lobacheva, O. L.; Berlinskii, I. V.

2010-12-01

190

Quantification of lanthanides in rocks using succinic acid-derivatized sorbents for on-line SPE-RP-ion-pair HPLC  

PubMed

The use of new poly(norbornene-block-7-oxanorborn-2ene-5,6-dicarboxylic acid)-coated silica-based sorbents as well as of beaded polymers based on poly(norborn-2-ene-5,6-dicarboxylic acid-co-1,4,4a,5,8,8a-hexahydro-1,4,5,8-exo-endo-dimethanonaphthalene) for the on-line preconcentration of lanthanides from rock digests and their subsequent RP-ion-pair HPLC separation is described. Block co-polymers of norborn-2-ene and 7-oxanorborn-2-ene-5,6-dicarboxylate used for coating were prepared by ring-opening metathesis polymerization (ROMP) and poly(norborn-2-ene-5,6-dicarboxylic acid-co-1,4,4a,5,8,-8a-hexahydro-1,4,5,8-exo-endo-dimethanonaphthalene)-based polymer beads were prepared by ring-opening metathesis precipitation polymerization. Both types of sorbents exhibit an extraordinarily good pH stability, are hydrophilic and therefore easily wetable by water alone, and show high extraction efficiencies for lanthanides within a pH of 3.5-5.5. The rare earth element (REE) content in the investigated rocks varied over 3 orders of magnitude (0.19-108 microg/g). REE concentrations prior to enrichment were typically in the range of 1-25 ng/mL; the total amount of each REE sorbed onto the precolumn was in the range of 8-270 ng. Extraction selectivities of the sorbent may be enhanced by adding 5-sulfosalicylic acid as a masking agent for iron and aluminum as well as methanol as an inhibitor for the precipitation of o-silicic acid. Gradient elution of the lanthanides from the precolumn and their subsequent separation on a RP-C18 column was achieved using hydroxyisobutyric acid (HIBA) and sodium octanesulfonate. Depending on the actual concentration of the lanthanides in the digests and in order to suppress interfering cations, UV detection was carried out with two different postderivatization reagents, 4-(2-pyridylazo)resorcinol (PAR) and arsenazo III. The high selectivity in enrichment as well as the complementary use of post-derivatization reagents allows the fast, quantitative, and highly reproducible quantification of REEs present in rocks by complete removal or suppression of all other interfering components. Thus, recoveries were found to be within a range of 97-103% for most REEs with relative standard deviations of 2-5%. PMID:10857641

Buchmeiser; Seeber; Tessadri

2000-06-01

191

Numbat: an interactive software tool for fitting ??-tensors to molecular coordinates using pseudocontact shifts  

Microsoft Academic Search

Pseudocontact shift (PCS) effects induced by a paramagnetic lanthanide bound to a protein have become increasingly popular\\u000a in NMR spectroscopy as they yield a complementary set of orientational and long-range structural restraints. PCS are a manifestation\\u000a of the ?-tensor anisotropy, the ??-tensor, which in turn can be determined from the PCS. Once the ??-tensor has been determined,\\u000a PCS become powerful

Christophe Schmitz; Mitchell J. Stanton-Cook; Xun-Cheng Su; Gottfried Otting; Thomas Huber

2008-01-01

192

Structure and properties of lanthanide halides  

NASA Astrophysics Data System (ADS)

Lanthanum and cerium bromides and chlorides form isomorphous alloy systems with the UCl3 type structure. These scintillating alloys exhibit high luminosity and proportional response, making them the first scintillators comparable to room temperature semiconductors for gamma spectroscopy; Ce(III) activated lanthanum bromide has recently enabled scintillating gamma ray spectrometers with < 3% FWHM energy resolutions at 662 keV. However brittle fracture of these materials impedes development of large volume crystals. Low fracture stress and perfect cleavage along prismatic planes cause material cracking during and after crystal growth. These and other properties pose challenges for material production and post processing; therefore, understanding mechanical behavior is key to fabricating large single crystals, and engineering of robust detectors and systems. Recent progress on basic structure and properties of the lanthanide halides is reported here, including thermomechanical and thermogravimetric analyses, hygroscopicity, yield strength, and fracture toughness. Observations including reversible hydrate formation under atmospheric pressure, loss of stoichiometry at high temperature, anisotropic thermal expansion, reactivity towards common crucible materials, and crack initiation and propagation under applied loads are reported. The fundamental physical and chemical properties of this system introduce challenges for material processing, scale-up, and detector fabrication. Analysis of the symmetry and crystal structure of this system suggests possible mechanisms for deformation and crack initiation under stress. The low c/a ratio and low symmetry relative to traditional scintillators indicate limited and highly anisotropic plasticity cause redistribution of residual process stress to cleavage planes, initiating fracture. This proposed failure mechanism and its implications for scale up to large diameter crystal growth are also discussed.

Doty, F. P.; McGregor, Douglas; Harrison, Mark; Findley, Kip; Polichar, Raulf

2007-10-01

193

Centrifugal atomization of lanthanide materials for cryogenic coolers  

Microsoft Academic Search

Until recently, Pb was the preferred heat exchanger matrix material used in low temperature cryocoolers; however, the heat capacity of Pb drops drastically below â¼15K and new matrix materials based on the lanthanide elements have been developed. These materials magnetically order at low temperatures and the entropy change associated with ordering contributes to the materials` heat capacities. The drawback to

Osborne

1994-01-01

194

Lanthanide ions promote the hydrolysis of 2,3-bisphosphoglycerate.  

PubMed

The 31P NMR studies showed that lanthanide ions promote the site-specific hydrolysis of 2,3-Bisphosphoglycerate (BPG) at pH 7.4 by cleaving the 2' phosphomonoester bond. The effect of fourteen trivalent lanthanide ions and Sc3+, and Y3+ were compared by the percentage of hydrolysis obtained by determining the inorganic phosphate produced. All the trivalent lanthanide ions promote the hydrolysis, but Sc3+ not. Among them, Ce3+ affects the reaction mostly. This was mainly attributed to the autooxidation of Ce3+ to Ce4+, since the promoting effect of Ce3+ is related to the increasing Ce4+ amount in the solution and depressed by adding sulphite. Ce4+ promotes the hydrolysis more efficiently than Ce3+ do. The pseudo first-order rate constant for the hydrolysis of BPG by Ce(SO4)2 (18.7 mM) at pH 1 and pH 2, 37 degrees C is 3.1 h(-1) and 0.65 h(-1) respectively. A mechanism with a hydroxo species as reactive intermediate was proposed for the trivalent lanthanide ions. The site-specificity was explainable by this mechanism. PMID:15259363

Zhu, Bing; Xue, Deping; Wang, Kui

2004-08-01

195

Plasmonic enhancement of lanthanides luminescence using metallic nanoparticles  

NASA Astrophysics Data System (ADS)

This work summarizes how plasmonic phenomena can enhance the fluorescence of lanthanides (Ln3+) coupled to metallic nanoparticles (MNP). Lanthanide-ions emission lines, based on 4f-4f transitions, are weak due to Laporte selection rules for optical transitions. This effect results in low absorption cross sections for excitation and long lifetimes for emission processes. We propose to use metallic nanoparticles in order to determine how plasmonic nanoparticles can enhance absorption and emission of two emblematic lanthanides ions used for bio-labeling and energy conversion, i.e., Eu3+ and Er3+. This work quantifies the average enhancement factor (AEF) is expected for different geometries of nanoparticle structures and compares it to previous studies. Then, we theoretically and numerically investigate metal-enhanced fluorescence of plasmonic core-shell nanoparticles doped with lanthanides ions. The shape and size of the particles are engineered to maximize the average enhancement factor of the overall doped shell. We show with theoretical considerations and numerical studies that the highest enhancement (11 in the visible and 7 in the near-infrared) is achieved by tuning either the dipolar or the quadrupolar particle resonance to the rare-earth ion's excitation wavelength. Additionally, the calculated AEFs are compared to experimental data reported in the literature, obtained under similar conditions (plasmon-mediated enhancement) or when a metal-Ln3+ energy-transfer mechanism is involved.

Berthelot, A.; Derom, S.; Abdellaoui, N.; Benamara, O.; Pillonnet, A.; Pereira, A.; Colas des Francs, G.; Moine, B.; Jurdyc, A.-M.

2014-03-01

196

On the suitability of lanthanides as actinide analogs  

SciTech Connect

With the current level of actinide materials used in civilian power generation and the need for safe and efficient methods for the chemical separation of these species from their daughter products and for long-term storage requirements, a detailed understanding of actinide chemistry is of great importance. Due to the unique bonding properties of the f-elements, the lanthanides are commonly used as structural and chemical models for the actinides, but differences in the bonding between these 4f and 5f elements has become a question of immediate applicability to separations technology. This brief overview of actinide coordination chemistry in the Raymond group at UC Berkeley/LBNL examines the validity of using lanthanide analogs as structural models for the actinides, with particular attention paid to single crystal X-ray diffraction structures. Although lanthanides are commonly accepted as reasonable analogs for the actinides, these comparisons suggest the careful study of actinide materials independent of their lanthanide analogs to be of utmost importance to present and future efforts in nuclear industries. (authors)

Raymond, Kenneth; Szigethy, Geza [Chemistry Department, University of California, Berkeley, CA, 94720-1460 (United States)

2008-07-01

197

Electronic structures and properties of lanthanide hexaboride nanowires  

NASA Astrophysics Data System (ADS)

The promising usage of lanthanide hexaboride nanowires as excellent electron emitter materials is generally attributed to the intrinsic low work functions of their bulk counterparts. Most analytical models for the field enhanced electron emission phenomenon adopt an underlying presumption of little or no change to the work function of the emission materials at the nanoscale. However, such a presumption is difficult to experimentally verify because current analytical models often employ empirical parameters such as the geometrically enhancement factors and the actual field emission areas are hard to determine. Herein, we report our density functional theory study of the size-dependence and element-specificity of the electronic structures and work functions of infinitely long lanthanide hexaboride nanowires constructed with n × n × ? unit cells (n = 1, 2, 3, and 4). Our modeling results reveal that the distinguished metal-like electronic properties and the low work function values of the sides of most examined nanowire systems are due to the abundant 4f and 5d states from the lanthanide metal atoms positioned at the Fermi level. These work function values are found to be weakly wire-size-dependent and element-dependent across the lanthanide series. They approach to the bulk values when their lateral wire-sizes are at or above 4-unit cell wide. The presence of abundance states at the Fermi level is found to be a common feature to rationalize the work functions of reported hexaboride systems.

Wang, Lu; Luo, Guangfu; Valencia, Daniel; Sierra Llavina, Carlos H.; Sabirianov, Renat. F.; Lu, Jing; Lu, Jun-Qiang; Mei, Wai-Ning; Li Cheung, Chin

2013-10-01

198

Electrochemical study of the mechanism of lanthanide extraction with thenoyltrifluoroacetone.  

PubMed

Current-scan polarography at the ascending-water electrode (AWE) was used to examine the electrochemical behavior of HTTA and La(3+), both in the absence and presence of neutral ligands, TOPO or MBDPO, and the light this sheds on the mechanism of extraction of lanthanides with HTTA, as well as the role played by mixed-ligand chelate formation. PMID:18964713

Yu, W H; Freiser, H

1989-01-01

199

Strong Exchange Coupling in Lanthanide Bis(Phthalocyaninato) Sandwich Compounds.  

National Technical Information Service (NTIS)

Bis (phthalocyaninato) lanthanide sandwich compounds, which have the formula Pc2-LnPc1-, have been synthesized for Ln = terbium, homium and lutecium. Low temperature magnetic susceptibility data for Ho (Pc)2 and Tb (Pc)2 show a reduction in moment from th...

K. L. Trojan W. E. Hatfield K. D. Kepler M. L. Kirk

1991-01-01

200

Tetraarylphosphonium-supported carbodiimide reagents: synthesis, structure optimization and applications.  

PubMed

New tetraarylphosphonium (TAP)-supported alkyl- and arylcarbodiimides were synthesized and used as coupling reagents for esterification reactions, amidation reactions and dehydration reactions of hydroxyesters. Taking advantage of the solubility properties imparted by the tetraarylphosphonium unit, a simple precipitation and filtration allowed complete separation of the urea by-products. This paper describes the structure optimization study of the various TAP-supported carbodiimide reagents to obtain the desired reactivity and solubility profile. Furthermore, we have demonstrated that the diimide reagent can be regenerated from the urea to recycle the reagents. PMID:18315003

Ginisty, Maryon; Roy, Marie-Noelle; Poupon, Jean-Christophe; Picard, Anne; Charette, André B

2008-04-01

201

Thionation with the reagent combination of phosphorus pentasulfide and hexamethyldisiloxane.  

PubMed

The combination of P4S10 and hexamethyldisiloxane efficiently converts esters, lactones, amides, lactams, and ketones to their corresponding thiono derivatives. In the presence of elemental sulfur, 3-oxoesters are converted to dithiolethiones by this reagent. Yields are comparable to or superior to those obtained with Lawesson's reagent. The method has the advantage that reagent-derived byproducts may be removed by a simple hydrolytic workup or by filtration through silica gel, rather than by chromatography, as required for Lawesson's reagent. PMID:12201768

Curphey, Thomas J

2002-09-01

202

Enhancement of anion binding in lanthanide optical sensors.  

PubMed

In the design of molecular sensors, researchers exploit binding interactions that are usually defined in terms of topology and charge complementarity. The formation of complementary arrays of highly cooperative, noncovalent bonding networks facilitates protein-ligand binding, leading to motifs such as the "lock-and-key". Synthetic molecular sensors often employ metal complexes as key design elements as a way to construct a binding site with the desired shape and charge to achieve target selectivity. In transition metal complexes, coordination number, structure and ligand dynamics are governed primarily by a combination of inner-sphere covalent and outer-sphere noncovalent interactions. These interactions provide a rich variable space that researchers can use to tune structure, stability, and dynamics. In contrast, lanthanide(III)-ligand complex formation and ligand-exchange dynamics are dominated by reversible electrostatic and steric interactions, because the unfilled f shell is shielded by the larger, filled d shell. Luminescent lanthanides such as terbium, europium, dysprosium, and samarium display many photophysical properties that make them excellent candidates for molecular sensor applications. Complexes of lanthanide ions act as receptors that exhibit a detectable change in metal-based luminescence upon binding of an anion. In our work on sensors for detection of dipicolinate, the unique biomarker of bacterial spores, we discovered that the incorporation of an ancillary ligand (AL) can enhance binding constants of target anions to lanthanide ions by as much as two orders of magnitude. In this Account, we show that selected ALs in lanthanide/anion systems greatly improve sensor performance for medical, planetary science, and biodefense applications. We suggest that the observed anion binding enhancement could result from an AL-induced increase in positive charge at the lanthanide ion binding site. This effect depends on lanthanide polarizability, which can be established from the ionization energy of Ln(3+) ? Ln(4+). These results account for the order Tb(3+) > Dy(3+) > Eu(3+) ? Sm(3+). As with many lanthanide properties, ranging from hydration enthalpy to vaporization energy, this AL-induced enhancement shows a large discrepancy between Tb(3+) and Eu(3+) despite their similarity in size, a phenomenon known as the "gadolinium break". This discrepancy, based on the unusual stabilities of the Eu(2+) and Tb(4+) oxidation states, results from the half-shell effect, as both of these ions have half-filled 4f-shells. The high polarizability of Tb(3+) explains the extraordinarily large increase in the binding affinity of anions for terbium compared to other lanthanides. We recommend that researchers consider this AL-induced enhancement when designing lanthanide-macrocycle optical sensors. Ancillary ligands also can reduce the impact of interfering species such as phosphate commonly found in environmental and physiological samples. PMID:24032446

Cable, Morgan L; Kirby, James P; Gray, Harry B; Ponce, Adrian

2013-11-19

203

Phenylethynyl endcapping reagents and reactive diluents  

NASA Technical Reports Server (NTRS)

A phenylethynyl composition which can be used to endcap nucleophilic species is employed in the production of phenylethynyl terminated reactive oligomers exclusively. These phenylethynyl terminated reactive oligomers display unique thermal characteristics, as exemplified by the model compound, 4-phenoxy 4'-phenylethynylbenzophenone, which is relatively stable at 200 C, but reacts at 350 C. In addition, a reactive diluent was prepared which decreases the melt viscosity of the phenylethynyl terminated oligomers and subsequently reacts therewith to increase density of the resulting thermoset. The novelty of this invention resides in the phenylethynyl composition used to terminate a nucleophilic reagent, resulting in the exclusive production of phenylethynyl terminated reactive oligomers which display unique thermal characteristics. A reactive diluent was also employed to decrease the melt viscosity of a phenylethynyl terminated reactive oligomer and to subsequently react therewith to increase the crosslink density of the resulting thermoset. These materials have features which make them attractive candidates for use as composite matrices and adhesives.

Jensen, Brian J. (inventor); Bryant, Robert G. (inventor); Hergenrother, Paul M. (inventor)

1994-01-01

204

The 3-(bromoacetamido)-propylamine hydrochloride: A novel sulfhydryl reagent and its future potential in the configurational study of S1-myosin  

NASA Technical Reports Server (NTRS)

Configurational study of S1-Myosin is an important step towards understanding force generation in muscle contraction. Previously reported NMR studies were corroborated. A new compound was synthesized, 3-(Bromoacetamido)-propylamine hydrochloride. Its potential as a sulfhydryl reagent provides an indirect but elegant approach towards future structural elucidation of S1-Myosin. The preliminary investigation has shown that this compound, BAAP, reacted with S1 in the absence of MgADP. The modified enzyme had a 2-fold increase in CaATPase activity and no detectable K-EDTA ATPase activity. Reaction of BAAP with S1 in the presence of MgADP resulted in a modified enzyme which retained a Ca-ATPase activity that was about 60 percent of the unmodified S1 and had essentially zero K-EDTA ATPase activity. Sulfhydryl titration indicated that about 1.5 and 3.5 SH groups per S1 molecule were blocked by BAAP in the absence and presence of MgADP, respectively. When coupled to a carboxyl group of EDTA, the resulting reagent could become a useful SH reagent in which chelated paramagnetic or luminescent lanthanide ions can be exploited to probe S1 conformation.

Sharma, Prasanta; Cheung, Herbert C.

1989-01-01

205

Chiral Shift Reagent Analysis of Enantioselectivity in Baker's Yeast Reductions of Ethylacetoacetate.  

ERIC Educational Resources Information Center

Described is a laboratory exercise that uses nuclear magnetic resonance to monitor enantiomeric excess in asymmetric reductions. The laboratory exercise has been used successfully with undergraduate organic chemistry students. (RH)

Lipkowitz, K. B.; Mooney, J. L.

1987-01-01

206

Synthesis, Characterization, and Use of a Cobalt(II) Complex as an NMR Shift Reagent.  

ERIC Educational Resources Information Center

Describes procedures for preparing acetylacetonate complex of cobalt(II), followed by spectrophotometric analysis to characterize the material, with additional characterization methods supplied by students to provide open-ended dimension for the experiment. (SK)

Goff, Harold M.; And Others

1982-01-01

207

Spectroscopic studies on the lanthanide sensitized luminescence and chemiluminescence properties of fluoroquinolone with different structure  

NASA Astrophysics Data System (ADS)

Lanthanide sensitized luminescence and chemiluminescence (CL) are of great importance because of the unique spectral properties, such as long lifetime, large Stokes shifts, and narrow emission bands characteristic to lanthanide ions (Ln 3+). With the fluoroquinolone (FQ) compounds including enoxacin (ENX), norfloxacin (NFLX), lomefloxacin (LMFX), fleroxacin (FLRX), ofloxacin (OFLX), rufloxacin (RFX), gatifloxacin (GFLX) and sparfloxacin (SPFX), the luminescence and CL properties of Tb 3+-FQ and Eu 3+-FQ complexes have been investigated in this contribution. Ce 4+-SO 32- in acidic conditions was taken as the CL system and sensitized CL intensities of Tb 3+-FQ and Eu 3+-FQ complexes were determined by flow-injection analysis. The luminescence and CL spectra of Tb 3+-FQ complexes show characteristic peaks of Tb 3+ at 490 nm, 545 nm, 585 nm and 620 nm. Complexes of Tb 3+-ENX, Tb 3+-NFLX, Tb 3+-LMFX and Tb 3+-FLRX display relatively strong emission intensity compared with Tb 3+-OFLX, Tb 3+-RFX, Tb 3+-GFLX and Tb 3+-SPFX. Quite weak peaks with unique characters of Eu 3+ at 590 nm and 617 nm appear in the luminescence and CL spectra of Eu 3+-ENX, but no notable sensitized luminescence and CL of Eu 3+ could be observed when Eu 3+ is added into other FQ. The distinct differences on emission intensity of Tb 3+-FQ and Eu 3+-FQ might originate from the different energy gap between the triplet levels of FQ and the excited levels of the Ln 3+. The different sensitized luminescence and CL signals among Tb 3+-FQ complexes could be attributed to different optical properties and substituents of these FQ compounds. The detailed mechanism involved in the luminescence and CL properties of Tb 3+-FQ and Eu 3+-FQ complexes has been investigated by analyzing the luminescence and CL spectra, quantum yields, and theoretical calculation results.

Sun, Chunyan; Ping, Hong; Zhang, Minwei; Li, Hongkun; Guan, Fengrui

2011-11-01

208

Spectroscopic studies on the lanthanide sensitized luminescence and chemiluminescence properties of fluoroquinolone with different structure.  

PubMed

Lanthanide sensitized luminescence and chemiluminescence (CL) are of great importance because of the unique spectral properties, such as long lifetime, large Stokes shifts, and narrow emission bands characteristic to lanthanide ions (Ln(3+)). With the fluoroquinolone (FQ) compounds including enoxacin (ENX), norfloxacin (NFLX), lomefloxacin (LMFX), fleroxacin (FLRX), ofloxacin (OFLX), rufloxacin (RFX), gatifloxacin (GFLX) and sparfloxacin (SPFX), the luminescence and CL properties of Tb(3+)-FQ and Eu(3+)-FQ complexes have been investigated in this contribution. Ce(4+)-SO(3)(2-) in acidic conditions was taken as the CL system and sensitized CL intensities of Tb(3+)-FQ and Eu(3+)-FQ complexes were determined by flow-injection analysis. The luminescence and CL spectra of Tb(3+)-FQ complexes show characteristic peaks of Tb(3+) at 490 nm, 545 nm, 585 nm and 620 nm. Complexes of Tb(3+)-ENX, Tb(3+)-NFLX, Tb(3+)-LMFX and Tb(3+)-FLRX display relatively strong emission intensity compared with Tb(3+)-OFLX, Tb(3+)-RFX, Tb(3+)-GFLX and Tb(3+)-SPFX. Quite weak peaks with unique characters of Eu(3+) at 590 nm and 617 nm appear in the luminescence and CL spectra of Eu(3+)-ENX, but no notable sensitized luminescence and CL of Eu(3+) could be observed when Eu(3+) is added into other FQ. The distinct differences on emission intensity of Tb(3+)-FQ and Eu(3+)-FQ might originate from the different energy gap between the triplet levels of FQ and the excited levels of the Ln(3+). The different sensitized luminescence and CL signals among Tb(3+)-FQ complexes could be attributed to different optical properties and substituents of these FQ compounds. The detailed mechanism involved in the luminescence and CL properties of Tb(3+)-FQ and Eu(3+)-FQ complexes has been investigated by analyzing the luminescence and CL spectra, quantum yields, and theoretical calculation results. PMID:21821467

Sun, Chunyan; Ping, Hong; Zhang, Minwei; Li, Hongkun; Guan, Fengrui

2011-11-01

209

Psychopathology of Shift Work.  

ERIC Educational Resources Information Center

Examined incidence and nature of general psychopathology among Nigerian shift workers (N=320). Found shift workers more significantly psychopathological than non-shift workers (p<0.001). Prominent disorders among shift workers were intellectual, sleep, mood, and general somatic disorders. No significant difference could be attributed to gender and…

Akinnawo, Ebenezer Olutope

1989-01-01

210

Lanthanide speciation in potential SANEX and GANEX actinide/lanthanide separations using tetra-N-donor extractants.  

PubMed

Lanthanide(III) complexes with N-donor extractants, which exhibit the potential for the separation of minor actinides from lanthanides in the management of spent nuclear fuel, have been directly synthesized and characterized in both solution and solid states. Crystal structures of the Pr(3+), Eu(3+), Tb(3+), and Yb(3+) complexes of 2,9-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-1,2,4-benzotriazin-3-yl)-1,10-phenanthroline (CyMe4-BTPhen) and the Pr(3+), Eu(3+), and Tb(3+) complexes of 6,6'-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-1,2,4-benzotriazin-3-yl)-2,2'-bypyridine (CyMe4-BTBP) were obtained. The majority of these structures displayed coordination of two of the tetra-N-donor ligands to each Ln(3+) ion, even when in some cases the complexations were performed with equimolar amounts of lanthanide and N-donor ligand. The structures showed that generally the lighter lanthanides had their coordination spheres completed by a bidentate nitrate ion, giving a 2+ charged complex cation, whereas the structures of the heavier lanthanides displayed tricationic complex species with a single water molecule completing their coordination environments. Electronic absorption spectroscopic titrations showed formation of the 1:2 Ln(3+)/L(N4-donor) species (Ln = Pr(3+), Eu(3+), Tb(3+)) in methanol when the N-donor ligand was in excess. When the Ln(3+) ion was in excess, evidence for formation of a 1:1 Ln(3+)/L(N4-donor) complex species was observed. Luminescent lifetime studies of mixtures of Eu(3+) with excess CyMe4-BTBP and CyMe4-BTPhen in methanol indicated that the nitrate-coordinated species is dominant in solution. X-ray absorption spectra of Eu(3+) and Tb(3+) species, formed by extraction from an acidic aqueous phase into an organic solution consisting of excess N-donor extractant in pure cyclohexanone or 30% tri-n-butyl phosphate (TBP) in cyclohexanone, were obtained. The presence of TBP in the organic phase did not alter lanthanide speciation. Extended X-ray absorption fine structure data from these spectra were fitted using chemical models established by crystallography and solution spectroscopy and showed the dominant lanthanide species in the bulk organic phase was a 1:2 Ln(3+)/L(N-donor) species. PMID:23438021

Whittaker, Daniel M; Griffiths, Tamara L; Helliwell, Madeleine; Swinburne, Adam N; Natrajan, Louise S; Lewis, Frank W; Harwood, Laurence M; Parry, Stephen A; Sharrad, Clint A

2013-04-01

211

Slow Release Of Reagent Chemicals From Gel Matrices  

NASA Technical Reports Server (NTRS)

Procedure developed for slow release of reagent chemicals into solutions. Simple and inexpensive and not subject to failure of equipment. Use of toothpaste-type tube or pump dispenser conceivably provides more controlled technique for storage and dispensation of gel matrix. Possible uses include controlled, slow release of reagents in chemical reactions, crystal growth, space-flight experiments, and preformed gel medications from packets.

Debnam, William J.; Barber, Patrick G.; Coleman, James

1988-01-01

212

Effect of organic reagents on neoprene, nitrile and natural rubbers  

Microsoft Academic Search

This paper reports the results from the chemical attacks of organic reagents on 5 different rubber specimens [nitrile rubber, neoprene, natural rubber (type: NR 40), natural rubber (type: NR 60), and natural rubber (type: food grade)]. The rubber samples were left in the organic reagents for a period of 4 weeks and were examined on weekly basis and later on

C. A. Baah; J. I. Baah

2001-01-01

213

Structure-kinetic relationship study of organozinc reagents.  

PubMed

Phenylzinc reagents prepared from various zinc halides show distinct kinetic features in the palladium-catalyzed Negishi-type oxidative coupling reaction, in which the phenylzinc reagent prepared from ZnI2 gives the highest rate. In situ infrared and X-ray absorption spectroscopy studies show that the higher reaction rate was observed for longer Zn-C bond distances. PMID:24964262

Zhang, Guanghui; Li, Jing; Deng, Yi; Miller, Jeffrey T; Kropf, A Jeremy; Bunel, Emilio E; Lei, Aiwen

2014-08-14

214

Macromolecular photoaffinity labeling wth radioactive photoactivable heterobifunctional reagents  

SciTech Connect

Three new photoactivable heterobifunctional reagents which can be radioiodinated have been synthesized. One of the radioactive reagents, the N-hydroxysuccinimide ester of 4-azidosalicylic acid was coupled to concanavalin A and the lectin derivative was used for the photoaffinity labeling of the lectin receptor on the erythrocyte ghost membrane.

Ji, T.H.; Ji, I.

1982-04-01

215

Redox mediation and hydrogen-generation with bipyridinium reagents  

DOEpatents

A variety of redox mediating agents employing bipyridinium reagents and such reagents in conjunction with dispersed noble metals, such as platinium, are disclosed as coatings for substrates and electrodes. The agents may be charged by an applied voltage or by photoelectric effects or may be equilibrated with hydrogen. The agents are useful in reducing biological materials and electrolytic hydrogen production.

Wrighton, Mark S. (Winchester, MA); Bookbinder, Dana C. (East Greenwich, RI); Bruce, James A. (Somerville, MA); Dominey, Raymond N. (Pensacola, FL); Lewis, Nathan S. (Palo Alto, CA)

1984-03-27

216

Dimethyl carbonate as a modern green reagent and solvent  

NASA Astrophysics Data System (ADS)

Published data on dimethyl carbonate as a safe reagent and solvent in organic synthesis are generalized and analyzed. The methods of dimethyl carbonate preparation and its use as methylating and carboxymethylating reagent are considered. The attention is focused on the environmentally safe processes corresponding to the green chemistry principles.

Aricò, F.; Tundo, Pietro

2010-08-01

217

Toward mechanistic understanding of nuclear reprocessing chemistries by quantifying lanthanide solvent extraction kinetics via microfluidics with constant interfacial area and rapid mixing.  

PubMed

The closing of the nuclear fuel cycle is an unsolved problem of great importance. Separating radionuclides produced in a nuclear reactor is useful both for the storage of nuclear waste and for recycling of nuclear fuel. These separations can be performed by designing appropriate chelation chemistries and liquid-liquid extraction schemes, such as in the TALSPEAK process (Trivalent Actinide-Lanthanide Separation by Phosphorus reagent Extraction from Aqueous Komplexes). However, there are no approved methods for the industrial scale reprocessing of civilian nuclear fuel in the United States. One bottleneck in the design of next-generation solvent extraction-based nuclear fuel reprocessing schemes is a lack of interfacial mass transfer rate constants obtained under well-controlled conditions for lanthanide and actinide ligand complexes; such rate constants are a prerequisite for mechanistic understanding of the extraction chemistries involved and are of great assistance in the design of new chemistries. In addition, rate constants obtained under conditions of known interfacial area have immediate, practical utility in models required for the scaling-up of laboratory-scale demonstrations to industrial-scale solutions. Existing experimental techniques for determining these rate constants suffer from two key drawbacks: either slow mixing or unknown interfacial area. The volume of waste produced by traditional methods is an additional, practical concern in experiments involving radioactive elements, both from disposal cost and experimenter safety standpoints. In this paper, we test a plug-based microfluidic system that uses flowing plugs (droplets) in microfluidic channels to determine absolute interfacial mass transfer rate constants under conditions of both rapid mixing and controlled interfacial area. We utilize this system to determine, for the first time, the rate constants for interfacial transfer of all lanthanides, minus promethium, plus yttrium, under TALSPEAK process conditions, as a first step toward testing the molecular mechanism of this separation process. PMID:21888347

Nichols, Kevin P; Pompano, Rebecca R; Li, Liang; Gelis, Artem V; Ismagilov, Rustem F

2011-10-01

218

Spectroscopic properties and luminescence enhancement of lanthanide mixed complexes Ln? 3L in zirconia glasses  

Microsoft Academic Search

The search for new compounds sensitizing lanthanides emission is of growing interest. Lanthanide mixed chelates of the type Ln?3L (L-Lewis base; 2,2?-bipyridine, 1.10-phenanthroline) seem to be promising in this area. In this work the new types of the lanthanide mixed chelates with phosphoro-azo-derivatives of ?-diketonates and 2,2?-bipyridine were incorporated in zirconia glasses by the sol–gel techniques. The thin zirconia films

R. Reisfeld; J. Legendziewicz; M. Puchalska; T. Saraidarov

2004-01-01

219

Lanthanide-containing polycations for monitoring polyplex dynamics via lanthanide resonance energy transfer.  

PubMed

Theranostic nanomaterials have emerged in the past decade that combine therapeutic delivery and diagnostic imaging into one package. Such materials offer the opportunity to aid diagnosis, track therapeutic biodistribution, and monitor drug release. We have developed a series of nucleic acid delivery polymers containing oligoethylene amines that are able to be protonated at physiological pH (for binding/compacting pDNA) and a lanthanide-chelating domain, which imparts diagnostic functionality. Diamine monomers (containing between 3 and 6 Boc-protected ethyleneamines) were prepared via a multistep procedure involving the selective protection and deprotection of primary and secondary amines. The polymer structures were then synthesized by step-growth polymerization of the oligoethylene diamines with a bisanhydride of diethylenetriamine pentaacetic acid (DTPA-BA), yielding degrees of polymerization between 18 and 24. Chelation of the polymers with gadolinium and terbium was performed to offer MRI contrast agent and luminescence properties, respectively. All of the polymer chelates were found to house approximately one water coordination site, as calculated by the Horrock's equation and possess longitudinal relaxivities (r1, on a per Gd basis) at least twice that of Magnevist, a clinical contrast agent. All the structures formed polyplexes with pDNA with highly positive zeta potentials and hydrodynamic diameters around 50-80 nm. Lanthanide resonance energy transfer (LRET) was used to monitor polyplex association and dissociation. Polyplexes were formed using the donor-acceptor pair comprising of terbium-chelated polymer with five ethyleneamines within the repeat unit (6c-Tb) and tetramethyl rhodamine (TMR)-labeled pDNA. Association/dissociation in the presence of heparin and NaCl was monitored. The effect of amine number along the polymer backbone on transfection efficiency and cytotoxicity was also investigated. None of the polymers revealed cytotoxic effects with cultured cells; however, the polymer with six ethyleneamines clearly offered the highest transfection efficiency. This preliminary study offers insight into the development of materials with the ability to monitor polyplex unpackaging over time within the cellular environment. PMID:24611467

Kelkar, Sneha S; Xue, Lian; Turner, S Richard; Reineke, Theresa M

2014-05-12

220

Reagent-loaded plastic microfluidic chips for detecting homocysteine  

NASA Astrophysics Data System (ADS)

This report describes the preliminary study on plastic microfluidic chips with pre-loaded reagents for detecting homocysteine (Hcy). All reagents needed in an Hcy immunoassay were included in a microfluidic chip to remove tedious assay steps. A simple and cost-effective bonding method was developed to realize reagent-loaded microfluidic chips. This technique uses an intermediate layer between two plastic substrates by selectively patterning polydimethylsiloxane (PDMS) on the embossed surface of microchannels and fixing the substrates under pressure. Using this bonding method, the competitive immunoassay for SAH, a converted form of Hcy, was performed without any damage to reagents in chips, and the results showed that the fluorescent signal from antibody antigen binding decreased as the SAH concentration increased. Based on the SAH immunoassay, whole immunoassay steps for Hcy detection were carried out in plastic microfluidic chips with all necessary reagents. These experiments demonstrated the feasibility of the Hcy immunoassay in microfluidic devices.

Suk, Ji Won; Jang, Jae-Young; Cho, Jun-Hyeong

2008-05-01

221

Development of new biotin/streptavidin reagents for pretargeting.  

PubMed

The high affinity of biotin for streptavidin has made this pair of molecules very useful for in vivo applications. To optimize reagents for one potential in vivo application, antibody-based pretargeting of cancer, we have prepared a number of new biotin and streptavidin derivatives. The derivatives developed include new radiolabeled biotin reagents, new protein biotinylation reagents, and new biotin multimers for cross-linking and/or polymerization of streptavidin. We have also modified streptavidin by site-directed mutation and chemical modification to improve its in vivo characteristics, and have developed new reagents for cross-linking antibody fragments with streptavidin. A brief overview of these new reagents is provided. PMID:10796993

Wilbur, D S; Pathare, P M; Hamlin, D K; Stayton, P S; To, R; Klumb, L A; Buhler, K R; Vessella, R L

1999-12-31

222

Standard Materials for Microbeam Analysis of Lanthanides and Actinides  

NASA Astrophysics Data System (ADS)

Traces of Th and U in naturally-occuring minerals monazite, xenotime and zircon are used for dating host rocks. Natural variations of actinide concentrations in some rock formations are well documented. Microbeam techniques perform dating in-situ where grains of indicator minerals are left intact in thin sections. Separated individual grains of these minerals are also routinely dated by Pb-isotope mass spectrometry. Ideal calibration materials will be compatible with multiple techniques. Quantitative analysis of low levels of lanthanides (REE), U, Th and Pb found in natural minerals requires standards containing similar concentrations of these elements. The ideal low-level standard suite will have materials with each REE cation present below 5%, similar to natural rare-earth phosphate minerals. In contrast, REE orthophosphates LnPO4 have cation concentrations from 59 to 64%, and ultraphosphates LnP5O14 from 27% to 32%. The concentrations of U and Pb must also be in the 1% range in the host REE phosphate. There are two competing limits to the synthesis of crystals with multiple cations in the REE sites. The crystal structure limits potential cation mixtures to selections within groups (La,Ce, Pr, Nd, Sm, Eu), (Gd, Tb, Dy, Ho), and (Er, Tm,Yb, Lu, Y). Complex L X-ray spectra limit the use of contiguous REE in a single material. There are two general synthetic routes for the preparation of lanthanide/actinide standard materials for beam analysis and dating. Lanthanide orthophosphates (LnPO4) are crystallized from lead-free heterogeneous fluxes; oligomers (metaphosphates LnP3O9 and ultraphosphates LnP5O14) are formed by condensation of phosphoric acid in the presence of cations. All of these trivalent lanthanide phosphate crystal structures are hosts for Th+4 and U+4, and in synthetic materals, Ca+2 is used for charge compensation. Our work focuses on the preparation of mixed-cation lanthanide metaphosphates and ultraphosphates. The solvent (essentially P2O5) provides redox conditions that favour Ce+3, Th+4, and U+4 instead of higher oxidation states. The absence of any cations other than those deliberately added permits positive control of cation mixtures in starting materials. The synthetic pathway—condensation of POx units--provides ideal conditions for the homogeneous distribution of cations including those with different charges. We present the results of synthesis, elemental analysis and imaging by XRF and SEM-EDX for mixed lanthanide-actinide phosphate materials.

Ellis, I.; Gorton, M.; Rucklidge, J. C.

2010-12-01

223

Crystal-field analysis of triply ionized lanthanides in Cs2NaLnCl6  

NASA Astrophysics Data System (ADS)

Optical spectra of the elpasolite hexachloride compounds Cs2NaLnCl6, where Ln represents one of the lanthanide ions, are analyzed with a crystal-field Hamiltonian of Oh symmetry. Crystal-field parameters, Bnm, are found that minimize the rms deviation between calculated and experimental energy levels for Ln=Ce, Pr, Nd, Eu, and Tb. A set of ''smoothed'' Bnm is found for the lanthanide series that predicts the spectroscopic properties of the remaining eight lanthanide ions. Predicted energy levels and g values are compared with available experimental data for all the lanthanides except Pm and Gd, and magnetic dipole intensities are computed.

Morrison, C. A.; Leavitt, R. P.; Wortman, D. E.

1980-09-01

224

Lanthanide Selective Sorbents: Self-Assembled Monolayers on Mesoporous Supports (SAMMS)  

SciTech Connect

Through the marriage of mesoporous ceramics with self-assembled monolayer chemistry, the genesis of a powerful new class of environmental sorbent materials has been realized. By coating the mesoporous ceramic backbone with a monolayer terminated with a lanthanide-specific ligand, it is possible to couple high lanthanide binding affinity with the high loading capacity (resulting from the extremely high surface area of the support). This lanthanide-specific ligand field is created by pairing a “hard” anionic Lewis base with a suitable synergistic ligand, in a favorable chelating geometry. Details of the synthesis, characterization, lanthanide binding studies, binding kinetics, competition experiments and sorbent regeneration studies are summarized.

Fryxell, Glen E.; Wu, Hong; Lin, Yuehe; Shaw, Wendy J.; Birnbaum, Jerome C.; Linehan, John C.; Nie, Zimin; Kemner, Kenneth M.; Kelly, Shelley

2004-11-01

225

Lanthanide Selective Sorbents: Self-Assembled Monolayers on Mesoporous Supports (SAMMS)  

SciTech Connect

Through the marriage of mesoporous ceramics with self-assembled monolayer chemistry, the genesis of a powerful new class of environmental sorbent materials has been realized. By coating the mesoporous ceramic backbone with a monolayer terminated with a lanthanide-specific ligand, it is possible to couple high lanthanide binding affinity with the high loading capacity (resulting from the extremely high surface area of the support). This lanthanide-specific ligand field is created by pairing a ''hard'' anionic Lewis base with a suitable synergistic ligand, in a favorable chelating geometry. Details of the synthesis, characterization, lanthanide binding studies, binding kinetics, competition experiments and sorbent regeneration studies are summarized

Fryxell, Glen E.; Wu, Hong; Lin, Yuehe; Shaw, Wendy J.; Birnbaum, Jerome C.; Linehan, John C.; Nie, Zimin; Kemner, K. M.; Kelly, Shelley

2004-11-01

226

The lanthanides and yttrium in minerals of the apatite group; a review  

USGS Publications Warehouse

More than 1000 analyses have been tabulated of the distribution of the lanthanides and yttrium in minerals of the apatite group, recalculated to atomic percentages. Average compositions have been calculated for apatites from 14 types of rocks. These show a progressive change of composition from apatites of granitic pegmatites, highest in the heavy lanthanides and yttrium, to those from alkalic pegmatites, highest in the light lanthanides and lowest in yttrium. This progression is clearly shown in plots of S (= at % La+Ce+Pr) vs the ratio La/Nd and of S vs the ratio 100Y/(Y+Ln), where Ln is the sum of the lanthanides. Apatites of sedimentary phosphorites occupy a special position, being relatively depleted in Ce and relatively enriched in yttrium and the heavy lanthanides, consequences of deposition from sea water. Apatites associated with iron ores are close in composition to apatites of carbonatites, alkalic ultramafic, and ultramafic rocks, being enriched in the light lanthanides and depleted in the heavy lanthanides. Their compositions do not support the hypothesis of Parak that the Kiruna-type ores are of sedimentary origin. Table 9 and Figures 1-3 show the dependence of lanthanide distribution on the nature of the host rock. Although a given analysis of the lanthanides does not unequivocally permit certain identification of the host rock, it can indicate a choice of highly probable host rocks.

Fleischer, Michael; Altschuler, Z. S.

1982-01-01

227

Lanthanide benzoates: a versatile building block for the construction of efficient light emitting materials.  

PubMed

On account of their intrinsic chemical and spectroscopic properties, luminescent lanthanide molecular materials find potential applications in lighting, optical communications, photonics and biomedical devices. This perspective article summarizes some recent seminal research work on luminescent properties and structural aspects of a series of lanthanide benzoate complexes featuring Eu(3+) and Tb(3+) ions. In particular, when modified with light-harvesting moieties, benzoates have proven to be efficient sensitizers for lanthanide ions. The photoluminescence properties of the various lanthanide benzoate coordination compounds have also been correlated with the electronic states of the newly designed antenna molecules. PMID:23258556

Reddy, M L P; Sivakumar, Sarika

2013-02-28

228

Standardization of reagents and methods used in cytological and histological practice with emphasis on dyes, stains and chromogenic reagents  

Microsoft Academic Search

Summary  The need for the standardization of reagents and methods used in the histology laboratory is demonstrated. After definitions of dyes, stains, and chromogenic reagents, existing standards and standards organizations are discussed. This is followed by practical instructions on how to standardize dyes and stains through the preparation of reference materials and the development of chromatographic methods. An overview is presented

H. O. Lyon; A. P. De Leenheer; R. W. Horobin; W. E. Lambert; E. K. W. Schulte; B. Van Liedekerke; D. H. Wittekind

1994-01-01

229

Lanthanide N,N-dimethylaminodiboranates as a new class of highly volatile chemical vapor deposition precursors.  

PubMed

New lanthanide N,N-dimethylaminodiboranate (DMADB) complexes of stoichiometry Ln(H(3)BNMe(2)BH(3))(3) and Ln(H(3)BNMe(2)BH(3))(3)(thf) have been prepared, where Ln = yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, and lutetium, except that isolation of the desolvated complexes proved difficult for Eu and Yb. The tetrahydrofuran (thf) complexes are all monomeric, and most of them adopt 13-coordinate structures in which each DMADB group chelates to the metal center by means of four B-H···Ln bridges (each BH(3) group is ?(2)H; i.e., forms two B-H···Ln interactions). For the smallest three lanthanides, Tm, Yb, and Lu, the metal center is 12 coordinate because one of the DMADB groups chelates to the metal center by means of only three B-H···Ln bridges. The structures of the base-free Ln(H(3)BNMe(2)BH(3))(3) complexes are highly dependent on the size of the lanthanide ions: as the ionic radius decreases, the coordination number decreases from 14 (Pr) to 13 (Sm) to 12 (Dy, Y, Er). The 14-coordinate complexes are polymeric: each metal center is bound to two chelating DMADB ligands and to two "ends" of two ligands that bridge in a Ln(?(3)H-H(3)BNMe(2)BH(3)-?(3)H)Ln fashion. In the 13-coordinate complexes, all three DMADB ligands are chelating, but the metal atom is also coordinated to one hydrogen atom from an adjacent molecule. The 12-coordinate complexes adopt a dinuclear structure in which each metal center is bound to two chelating DMADB ligands and to two ends of two ligands that bridge in a Ln(?(2)H-H(3)BNMe(2)BH(3)-?(2)H)Ln fashion. The complexes react with water, and the partial hydrolysis product [La(H(3)BNMe(2)BH(3))(2)(OH)](4) adopts a structure in which the lanthanum and oxygen atoms form a distorted cube; each lanthanum atom is connected to three bridging hydroxyl groups and to two chelating DMADB ligands. One B-H bond of each chelating DMADB ligand forms a bridge to an adjacent metal center. Field ionization MS data, melting and decomposition points, thermogravimetric data, and NMR data, including an analysis of the paramagnetic lanthanide induced shifts (LIS), are reported for all of the complexes. The Ln(H(3)BNMe(2)BH(3))(3) compounds, which are highly volatile and sublime at temperatures as low as 65 °C in vacuum, are suitable for use as chemical vapor deposition (CVD) and atomic layer deposition (ALD) precursors to thin films. PMID:22686567

Daly, Scott R; Kim, Do Young; Girolami, Gregory S

2012-07-01

230

Oxygen defects of actinide, lanthanide oxides, and their solid solutions  

NASA Astrophysics Data System (ADS)

To reveal the nature of the oxygen defects in actinide, lanthanide oxides, and their solid solutions, the relations between the molar ratio of oxygen to metal, O/M, and the oxygen potentials of these oxides in our previous studies were reviewed. These relations were then compared with those between O/M and the oxygen potentials in the literature, with reference to the phase relations and the constituent cationic valences and radii of these oxides. Consequently, we found consistent properties in the relations between O/M and the oxygen potentials of actinide, lanthanide oxides, and their solid solutions, in addition to the dependence of the relations on the crystal structures (e.g., fluorite-type, pyrochlore-type, and cubic sesquioxide-type).

Otobe, Haruyoshi

2013-11-01

231

Novel microporous lanthanide silicates with tobermorite-like structure.  

PubMed

The synthesis and structural characterization of microporous lanthanide silicates (Na(1.08)K(0.5)Ln(1.14)Si(3)O(8.5).1.78H(2)O, Ln = Eu, Tb, Sm, Ce) are reported. The structure of these solids is closely related with the structure of hydrated calcium silicate minerals known as tobermorites and was solved by powder X-ray diffraction ab initio (direct) methods and further characterized by chemical analysis, thermogravimetry, scanning electron microscopy, (23)Na and (29)Si MAS NMR and luminescence spectroscopy. These materials combine microporosity with interesting photoluminescence properties, and their structural flexibility allows fine-tuning of luminescence properties, by introducing a second type of lanthanide ion in the framework. Thus, they may find applications in new types of sensors. PMID:14624607

Ferreira, Artur; Ananias, Duarte; Carlos, Luís D; Morais, Cláudia M; Rocha, João

2003-11-26

232

Synthesis and luminescence of lanthanide ions in nanoscale insulating hosts  

SciTech Connect

This review summarizes recent work in nanostructured insulating materials that contain optically active lanthanide ions. These materials find applications in lasers, optical amplifiers, and optical-display phosphors. This review concentrates on the synthesis and luminescence spectroscopy of lanthanide-containing nanostructured particles, films, and composites. Spectroscopic studies range from basic luminescence spectroscopy and quantum efficiency measurements to high-resolution spectroscopic studies that investigate the phonon dynamics and electron-phonon interaction as a function of particle size. This review identifies several areas for further study, including the location, distribution, or segregation of dopants in nanoparticles; the efficiency of energy transfer across interfaces; and the effects of quantum confinement or changes in phonon dynamics and electron-phonon interactions on the radiative and nonradiative relaxation rates in localized luminescent dopants.

Tissue, B.M. [Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States). Dept. of Chemistry] [Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States). Dept. of Chemistry

1998-10-01

233

Lanthanide-based functional misfit-layered nanotubes.  

PubMed

The synthesis of nanotubes from layered compounds has generated substantial scientific interest. "Misfit" layered compounds (MLCs) of the general formula [(MX)1+x ]m [TX2 ]n , where M can include Pb, Sb, rare earths; T=Cr, Nb, and X=S, Se can form layered structures, even though each sub-system alone is not necessarily a layered or a stable compound. A simple chemical method is used to synthesize these complex nanotubes from lanthanide-based misfit compounds. Quaternary nanotubular structures formed by partial substitution of the lanthanide atom in nanotubes by other elements are also confirmed. The driving force and mechanism of formation of these nanotubes is investigated by systematic temperature and time-dependent studies. A stress-inducement mechanism is proposed to explain the formation of the nanotubes. The resulting materials may find applications in fields that include thermoelectrics, light emitters, and catalysis and address fundamental physical issues in low dimensions. PMID:24898937

Panchakarla, Leela S; Popovitz-Biro, Ronit; Houben, Lothar; Dunin-Borkowski, Rafal E; Tenne, Reshef

2014-07-01

234

Growth and characterization of polycrystalline lanthanide halide scintillators  

Microsoft Academic Search

We are exploring a novel time- and cost-efficient approach to produce robust, large-volume polycrystalline lanthanide halide scintillators using a hot wall evaporation (HWE) technique. To date, we have fabricated LaBr3:Ce and LaCl3:Ce films (slabs) measuring up to 7cm in diameter and 7+mm in thickness (20–25cm3 in volume) on quartz substrates. These polycrystalline scintillators exhibit very bright emissions approaching those exhibited

V. V. Nagarkar; S. R. Miller; V. Gelfandbein; U. Shirwadkar; V. Gaysinskiy

2011-01-01

235

Gibbs energies of formation of hydroxides of lanthanides and yttrium  

Microsoft Academic Search

The pH values of the formation of hydrates in solutions of yttrium(III), cerium(III), samarium(III), europium(III), erbium(III), and ytterbium(III) were determined by conductometric titration. The solubility products and Gibbs energies of formation for hydroxides for the elements listed were calculated. The average Gibbs energy of dissolution for lanthanide hydroxides was found to be approximately 149.83 ± 0.90 kJ\\/mol. The Gibbs energies

D. E. Chirkst; O. L. Lobacheva; I. V. Berlinskii

2010-01-01

236

Photoacoustic Spectral Study of Lanthanide Complexes Doped in Silica Matrix  

NASA Astrophysics Data System (ADS)

Lanthanide phenanthroline (phen) complexes Eu(phen)2Cl3{\\cdot } 2H2O and Nd(phen)2Cl3{\\cdot } 2H2O were incorporated into a silica matrix by an ultrasonic assisted sol-gel method. In the region of ligand absorption, the photoacoustic (PA) intensity for a lanthanide complex is the same as in wet gels. Upon heat treatment at 120° C, however, the PA intensity of a Nd(phen)2Cl3{\\cdot }2H2 O-doped sample is much larger than that of a Eu(phen)2Cl3 {\\cdot } 2H2 O-doped sample. The characteristic emissions of Eu^{3+} complex-doped samples were used to interpret the stability of the complex in silica matrices. The luminescence spectra are consistent with the PA results. The study indicates that phen can only coordinate with lanthanide ions in a silica matrix after a suitable heat treatment. Moreover, the covalency parameters and PA bands of f-f transionts of Nd^{3+} have been used to study the formation of the complex in a silica matrix.

Yang, Y. T.; Gao, B.; Zhang, S. Y.; Liu, X. J.

2014-05-01

237

Magnetic Relaxation Mechanisms in Lanthanide Single Molecule Magnets  

NASA Astrophysics Data System (ADS)

Ab initio investigation of multiplet spectrum of lanthanides in archetypal coordination geometries shows an unexpected regular structure consisting of (i) mirror symmetry of anisotropic magnetic properties of doublet states, (ii) high magnetic axiality of low-lying and high-lying doublets, comparable to complexes with ideal axial symmetry, and (iii) the strong rotation of the anisotropy axes of individual doublets [1]. The obtained high axiality of the ground doublet states explains the SMM behaviour of low-symmetry lanthanide complexes. Ab initio calculations predict that depending on the relative orientation of anisotropy axes in different doublet states, the relaxation can proceed via the first or the second excited state. Here we report new lanthanide cage complexes where two competing relaxation pathways through the first and second excited states are observed, leading to very high energy barriers for loss of magnetisation [2]. [1] L. Ungur, L.F. Chibotaru, P.C.C.P., 2011, 13, 20086--20090. [2] R.J. Blagg, L. Ungur, F. Tuna, D. Collison, E.J.L. McInnes L.F. Chibotaru, R.E.P. Winpenny,. Nat. Chem., submitted.

Chibotaru, Liviu; Ungur, Liviu; McInnes, Eric; Winpenny, Richard

2013-03-01

238

Characterization and Classification of Lanthanides by Multivariate-Analysis Methods  

NASA Astrophysics Data System (ADS)

A chemometric study was conducted on a data set consisting of 18 characteristics, mainly physical properties of the 14 lanthanides and lanthanum, including Sc and Y. Classical methods of multivariate analysis, namely, principal component analysis (PCA) and cluster analysis (CA) were applied. The results obtained by using the Statistica software package are presented and discussed concerning the correlations between the properties and those between the elements themselves. The discussion and findings are based on the tables of correlation, the eigenvectors and eigenvalues of PCA, the 2D- and 3D-representations of the loadings of variables and scores of the elements corresponding to the first principal components, including also the dendrograms obtained by using CA. Loadings scatterplots are used as a display tool for examining the relationships between properties, looking for trends, grouping, or outliers. In the same way, the scatterplots of scores emphasized the difference between La and the lanthanides on the one side and Sc and Y on the other and support setting Lu as their homologue, rather than La. On the basis of these findings, a ”periodic system“ of the lanthanides is suggested that agrees well with chemical intuition.

Horovitz, Ossi; Sârbu, Costel

2005-03-01

239

Novel open-framework architectures in lanthanide phosphonates  

NASA Astrophysics Data System (ADS)

Two novel three-dimensional lanthanide coordination polymers have been prepared hydrothermally with the phosphonic acid N,N-piperazine bis(methylenephosphonic acid), H 2O 3PCH 2N(C 2H 4) 2NCH 2PO 3H 2 ( LH 4). The structures of Gd 2( LH 2) 3?3H 2O (I) and Nd 2( LH 2) 3?9H 2O (II) have been characterised by single crystal X-ray techniques. One-dimensional 'lanthanide-phosphate' chains are a key feature in both structures, although there are major structural differences between the chains, with (I) displaying octahedral GdO 6 coordination and (II) showing eight-coordinate NdO 8 polyhedra. In each case, three-dimensional connectivity is completed by coordination of the phosphonate group resulting in open framework structures encapsulating loosely bound water molecules. Isostructural Y 3+ and Yb 3+ analogues of (I) have been prepared, suggesting that cation size is a key factor in controlling the differing reaction products. In the case of Y 2( LH 2) 3?5H 2O, isostructural to (I), it is shown that the extra-framework water molecules may be removed reversibly without framework collapse. Structural relationships to other known lanthanide phosphonates are discussed.

Groves, John A.; Stephens, Nicholas F.; Wright, Paul A.; Lightfoot, Philip

2006-03-01

240

Humic and hymatomelanic acids interaction with lanthanide ions  

NASA Astrophysics Data System (ADS)

The interactions of lanthanide ions, REE(III), with semiquinone radicals naturally occurring in humic (HA) and hymatomelanic (HY) acids of different origin were studied mainly by EPR spectroscopy. Quantitative EPR analysis proved that only the semiquinone free radical concentration in both, HA and HY, was affected by interaction with some of the lanthanide ions, whereas the EPR g parameters of the formed radical-REE(III) complexes remained unchanged. The radical concentration was practically unaffected by the REE(III) ions with 4f1-4f6 electron configurations and in some degree increased by REE(III) ions with 4f8-4f14 configuration. The lanthanide playing an exceptional role was Gd(III) (4f7), which diminished strongly the free radicals concentration. The quenching ability of Gd(III) was stronger towards the radicals provided by HA than by HY, what was assigned to higher content in HA of both, oxygen-containing functional groups and conjugated aromatic rings, leading to more efficient Gd(III)-radical interaction. The semiquinone free radicals of HA and HY originated from the compost were more reactive than those from peat, as the humic acids from mature compost with less bulk density have more accessible functional groups.

Jerzykiewicz, Maria

2012-10-01

241

Semiempirical quantum chemistry model for the lanthanides: RM1 (Recife Model 1) parameters for dysprosium, holmium and erbium.  

PubMed

Complexes of dysprosium, holmium, and erbium find many applications as single-molecule magnets, as contrast agents for magnetic resonance imaging, as anti-cancer agents, in optical telecommunications, etc. Therefore, the development of tools that can be proven helpful to complex design is presently an active area of research. In this article, we advance a major improvement to the semiempirical description of lanthanide complexes: the Recife Model 1, RM1, model for the lanthanides, parameterized for the trications of Dy, Ho, and Er. By representing such lanthanide in the RM1 calculation as a three-electron atom with a set of 5 d, 6 s, and 6 p semiempirical orbitals, the accuracy of the previous sparkle models, mainly concentrated on lanthanide-oxygen and lanthanide-nitrogen distances, is extended to other types of bonds in the trication complexes' coordination polyhedra, such as lanthanide-carbon, lanthanide-chlorine, etc. This is even more important as, for example, lanthanide-carbon atom distances in the coordination polyhedra of the complexes comprise about 30% of all distances for all complexes of Dy, Ho, and Er considered. Our results indicate that the average unsigned mean error for the lanthanide-carbon distances dropped from an average of 0.30 Å, for the sparkle models, to 0.04 Å for the RM1 model for the lanthanides; for a total of 509 such distances for the set of all Dy, Ho, and Er complexes considered. A similar behavior took place for the other distances as well, such as lanthanide-chlorine, lanthanide-bromine, lanthanide, phosphorus and lanthanide-sulfur. Thus, the RM1 model for the lanthanides, being advanced in this article, broadens the range of application of semiempirical models to lanthanide complexes by including comprehensively many other types of bonds not adequately described by the previous models. PMID:24497945

Filho, Manoel A M; Dutra, José Diogo L; Rocha, Gerd B; Simas, Alfredo M; Freire, Ricardo O

2014-01-01

242

Selective removal of lanthanides from natural waters, acidic streams and dialysate  

PubMed Central

The increased demand for the lanthanides in commercial products result in increased production of lanthanide containing ores, which increases public exposure to the lanthanides, both from various commercial products and from production wastes/effluents. This work investigates lanthanide (La, Ce, Pr, Nd, Eu, Gd and Lu) binding properties of self-assembled monolayers on mesoporous silica supports (SAMMS™), that were functionalized with diphosphonic acid (DiPhos), acetamide phosphonic acid (AcPhos), propionamide phosphonic acid (Prop-Phos), and 1-hydroxy-2-pyridinone (1,2-HOPO), from natural waters (river, ground and sea waters), acid solutions (to mimic certain industrial process streams), and dialysate. The affinity, capacity, and kinetics of the lanthanide sorption, as well as regenerability of SAMMS materials were investigated. Going from the acid side over to the alkaline side, the AcPhos- and DiPhos-SAMMS maintain their outstanding affinity for lanthanides, which enable the use of the materials in the systems where the pH may fluctuate. In acid solutions, Prop-Phos- and 1,2-HOPO-SAMMS have differing affinity along the lanthanide series, suggesting their use in chromatographic lanthanide separation. Over 95% of 100 µg/L of Gd in dialysate was removed by the Prop-Phos-SAMMS after 1 min and 99% over 10 min. SAMMS can be regenerated with an acid wash (0.5 M HCl) without losing the binding properties. Thus, they have a great potential to be used as in large-scale treatment of lanthanides, lanthanide separation prior to analytical instruments, and in sorbent dialyzers for treatment of acute lanthanide poisoning.

Yantasee, Wassana; Fryxell, Glen E.; Addleman, R. Shane; Wiacek, Robert J.; Koonsiripaiboon, View; Pattamakomsan, Kanda; Sukwarotwat, Vichaya; Xu, Jide; Raymond, Kenneth N.

2009-01-01

243

21 CFR 866.3332 - Reagents for detection of specific novel influenza A viruses.  

Code of Federal Regulations, 2010 CFR

...Reagents for detection of specific novel influenza A viruses. 866.3332 Section 866...Reagents for detection of specific novel influenza A viruses. (a) Identification . Reagents for detection of specific novel influenza A viruses are devices that are...

2009-04-01

244

21 CFR 866.3332 - Reagents for detection of specific novel influenza A viruses.  

Code of Federal Regulations, 2010 CFR

...Reagents for detection of specific novel influenza A viruses. 866.3332 Section 866...Reagents for detection of specific novel influenza A viruses. (a) Identification . Reagents for detection of specific novel influenza A viruses are devices that are...

2010-04-01

245

21 CFR 866.3332 - Reagents for detection of specific novel influenza A viruses.  

Code of Federal Regulations, 2013 CFR

...Reagents for detection of specific novel influenza A viruses. 866.3332 Section 866...Reagents for detection of specific novel influenza A viruses. (a) Identification . Reagents for detection of specific novel influenza A viruses are devices that are...

2013-04-01

246

Lanthanide-enhanced luminescence (LEL) with one and two photon excitation of Quantum Dyes lanthanide(III)-macrocycles  

NASA Astrophysics Data System (ADS)

Improvements in the lanthanide enhanced luminescence (LEL) protocol have facilitated the use of the recently synthesized Eu(III)-macrocycle-mono-isothiocyanate, Quantum Dye, as a label. It was discovered that a homogeneous solution in ethanol or other solvent could be used to produce the lanthanide enhanced luminescence (LEL) effect, provided that the solution was permitted to evaporate. This protocol has been applied to the direct staining of cells in S phase, and was optimized for solid phase assays with Quantum Dye labeled streptavidin. Preliminary studies indicate that cells stained with the europium Quantum Dye can be observed both by conventional UV laser excitation and by infrared two-photon confocal microscopy. An enhancer has been found that enables the observation of simultaneous emissions from both the europium and terbium Quantum Dyes.

Leif, Robert C.; Becker, Margie C.; Bromm, Alfred J., Jr.; Chen, Nanguang; Cowan, Ann E.; Vallarino, Lidia M.; Yang, Sean; Zucker, Robert M.

2004-07-01

247

Praseodymium Nitrate and Neodymium Complexation with Organophosphorus Reagents in Supercritical Carbon Dioxide Solvent  

SciTech Connect

Complex formation reactions of praseodymium nitrate hexahydrate, and neodymium nitrate hexahydrate salts with tri-n-butyl phosphate (TBP) and several other neutral organophosphorus reagents were investigated in supercritical carbon dioxide. The concentration of the metal complexes in the supercritical fluid (SCF) phase was determined using UV-Vis and luminescence spectroscopies. The stoichiometry of the complexes was determined using the mole-ratio method. Extraction equilibrium constants were calculated from the spectral data using least-squares regression and hard-equilibria models. UV-Vis absorbance data indicate that praseodymium nitrate and neodymium nitrate both form 1:4 lanthanide–tributyl phosphate complexes in supercritical carbon dioxide at 308 K. The conditional extraction coefficients for those two systems were calculated to be log Kex=7.45±0.06 for the praseodymium system and log Kex=7.52±0.03 for the neodymium system. For comparison, neodymium nitrate complexation reactions with tri-n-butyl phosphate and tributyl phosphite (TBPO3) were studied in hexane under ambient conditions. UV-Vis data indicate that a 1:4 neodymium–tributyl phosphate complex is formed in hexane with a conditional extraction coefficient of log Kex=3.4±0.2. Tributyl phosphite forms a 1:8 complex with neodymium in hexane with a conditional extraction coefficient of log Kex=11.0±0.1. Neodymium nitrate was titrated with other organophosphorus reagents, tributyl phosphite and tributyl phosphine oxide (TBPO), in supercritical carbon dioxide to investigate differences between neutral oxygen donor ligands and neutral phosphorus donor ligands. UV-Vis and luminescence data indicate that neodymium nitrate forms a 1:8 complex with tributyl phosphite and a 1:5 complex with tributyl phosphine oxide, compared to a 1:4 complex with tri-n-butyl phosphate. The conditional extraction coefficient for the 1:8 neodymium–tributyl phosphite system was calculated as log Kex=21.4±0.2 from UV-Vis data, and log Kex=19.8±0.2 from luminescence data. The conditional extraction coefficient for the 1:5 neodymium–tributyl phosphine oxide complex was calculated as log Kex=7.83±0.05.

Robert V. Fox; R. Duane Ball; Peter de B. Harrington; Harry W. Rollins; John G. Jolley; Chien M. Wai

2004-11-01

248

Separation and determination of trace metal ions using organic chelating reagents  

SciTech Connect

The four reagents tested were N,N-dihexylacetamide (DHA), 2,6-diacetylpyridine bis(furoylhydrazone) (H/sub 2/dapf), 1,3-dimethyl-4-acetyl-2-pyrazolin-5-one (DMAP) and N-methylfurohydroxamic acid (NMFHA). DHA and H/sub 2/dapf were investigated for their complex formation with uranium, and DMAP and NMFHA were used as chelating agents in high performance liquid chromatography (HPLC). Uranium(VI) is preferentially extracted from nitric acid solutions using DHA in toluene. The extraction characteristics of the U-DHA complex are studied. A 119,000 ..mu..gL/sup -1/ U solution is analyzed for twenty-six elements. The U is extracted with DHA, and the trace metal ions are then determined by inductively coupled plasma-mass spectrometry. Uranium must be removed from the sample before analysis to prevent ionization suppression. H/sub 2/dapf is synthesized and characterized. Studies of the complexation of metal ions with H/sub 2/dapf is described. U(VI) forms a stable complex with H/sub 2/dapf, and a procedure for selectively determining trace U by spectrophotometry is presented. DMAP complexes of Cu(II), Fe(III), Ga(III), Th(IV), U(VI), V(V), and Zr(IV) are separated using reversed phase HPLC. NMFHA complex of Al(III), Fe(III), Hf(IV), Nb(V), Sb(III), and Zr(IV) are separated using reversed phase HPLC. NMFHA is also used to separate uranium(VI) from trace lanthanide ions. 266 refs., 46 figs., 24 tabs

Palmieri, M.D.

1987-11-01

249

Palau'chlor: A Practical and Reactive Chlorinating Reagent.  

PubMed

Unlike its other halogen atom siblings, the utility of chlorinated arenes and (hetero)arenes are twofold: they are useful in tuning electronic structure as well as acting as points for diversification via cross-coupling. Herein we report the invention of a new guanidine-based chlorinating reagent, CBMG or "Palau'chlor", inspired by a key chlorospirocyclization en route to pyrrole imidazole alkaloids. This direct, mild, operationally simple, and safe chlorinating method is compatible with a range of nitrogen-containing heterocycles as well as select classes of arenes, conjugated ?-systems, sulfonamides, and silyl enol ethers. Comparisons with other known chlorinating reagents revealed CBMG to be the premier reagent. PMID:24758725

Rodriguez, Rodrigo A; Pan, Chung-Mao; Yabe, Yuki; Kawamata, Yu; Eastgate, Martin D; Baran, Phil S

2014-05-14

250

Widely Applicable Metallacarborane Reagents for ?-Conjugated Systems.  

PubMed

The compounds [N(CH3)4][3,3'-Co(8-(p-C6H4C2H3)-1,2-C2B9H10)(1',2'-C2B9H11)], [N(CH3)4][3,3'-Co(8-(p-C6H4CHO)-1,2-C2B9H10)(1',2'-C2B9H11)], and [N(CH3)4][3,3'-Co(8-(m-C6H4CHO)-1,2-C2B9H10)(1',2'-C2B9H11)] were synthesized using an easy methodology, in very good yields and large quantities, which are important requisites to be employed as starting reagents. They have been fully characterized by elemental analysis, IR, NMR, and MALDI-TOF-MS, and the crystal structures of [N(CH3)4][3,3'-Co(8-(p-C6H4C2H3)-1,2-C2B9H10)(1',2'-C2B9H11)] and [N(CH3)4][3,3'-Co(8-(p-C6H4CHO)-1,2-C2B9H10)(1',2'-C2B9H11)] were elucidated by single-crystal X-ray diffraction. These compounds, having terminal formyl and vinyl functional groups, are suitable platforms to involve the aromatic cobaltabisdicarbollide unit into extended ?-conjugated systems. It is expected that these synthons will facilitate the applicability of metallacarboranes in a wide variety of different fields, where ?-conjugated systems are needed to keep electronic communication. PMID:24819777

Farràs, Pau; Musteti, Ana D; Rojo, Isabel; Viñas, Clara; Teixidor, Francesc; Light, Mark E

2014-06-01

251

Polymeric Microspheres as Protein Transduction Reagents*  

PubMed Central

Discovering the function of an unknown protein, particularly one with neither structural nor functional correlates, is a daunting task. Interaction analyses determine binding partners, whereas DNA transfection, either transient or stable, leads to intracellular expression, though not necessarily at physiologically relevant levels. In theory, direct intracellular protein delivery (protein transduction) provides a conceptually simpler alternative, but in practice the approach is problematic. Domains such as HIV TAT protein are valuable, but their effectiveness is protein specific. Similarly, the delivery of intact proteins via endocytic pathways (e.g. using liposomes) is problematic for functional analysis because of the potential for protein degradation in the endosomes/lysosomes. Consequently, recent reports that microspheres can deliver bio-cargoes into cells via a non-endocytic, energy-independent pathway offer an exciting and promising alternative for in vitro delivery of functional protein. In order for such promise to be fully exploited, microspheres are required that (i) are stably linked to proteins, (ii) can deliver those proteins with good efficiency, (iii) release functional protein once inside the cells, and (iv) permit concomitant tracking. Herein, we report the application of microspheres to successfully address all of these criteria simultaneously, for the first time. After cellular uptake, protein release was autocatalyzed by the reducing cytoplasmic environment. Outside of cells, the covalent microsphere–protein linkage was stable for ?90 h at 37 °C. Using conservative methods of estimation, 74.3% ± 5.6% of cells were shown to take up these microspheres after 24 h of incubation, with the whole process of delivery and intracellular protein release occurring within 36 h. Intended for in vitro functional protein research, this approach will enable study of the consequences of protein delivery at physiologically relevant levels, without recourse to nucleic acids, and offers a useful alternative to commercial protein transfection reagents such as Chariot™. We also provide clear immunostaining evidence to resolve residual controversy surrounding FACS-based assessment of microsphere uptake.

Nagel, David; Behrendt, Jonathan M.; Chimonides, Gwen F.; Torr, Elizabeth E.; Devitt, Andrew; Sutherland, Andrew J.; Hine, Anna V.

2014-01-01

252

Polymeric microspheres as protein transduction reagents.  

PubMed

Discovering the function of an unknown protein, particularly one with neither structural nor functional correlates, is a daunting task. Interaction analyses determine binding partners, whereas DNA transfection, either transient or stable, leads to intracellular expression, though not necessarily at physiologically relevant levels. In theory, direct intracellular protein delivery (protein transduction) provides a conceptually simpler alternative, but in practice the approach is problematic. Domains such as HIV TAT protein are valuable, but their effectiveness is protein specific. Similarly, the delivery of intact proteins via endocytic pathways (e.g. using liposomes) is problematic for functional analysis because of the potential for protein degradation in the endosomes/lysosomes. Consequently, recent reports that microspheres can deliver bio-cargoes into cells via a non-endocytic, energy-independent pathway offer an exciting and promising alternative for in vitro delivery of functional protein. In order for such promise to be fully exploited, microspheres are required that (i) are stably linked to proteins, (ii) can deliver those proteins with good efficiency, (iii) release functional protein once inside the cells, and (iv) permit concomitant tracking. Herein, we report the application of microspheres to successfully address all of these criteria simultaneously, for the first time. After cellular uptake, protein release was autocatalyzed by the reducing cytoplasmic environment. Outside of cells, the covalent microsphere-protein linkage was stable for ?90 h at 37 °C. Using conservative methods of estimation, 74.3% ± 5.6% of cells were shown to take up these microspheres after 24 h of incubation, with the whole process of delivery and intracellular protein release occurring within 36 h. Intended for in vitro functional protein research, this approach will enable study of the consequences of protein delivery at physiologically relevant levels, without recourse to nucleic acids, and offers a useful alternative to commercial protein transfection reagents such as Chariot™. We also provide clear immunostaining evidence to resolve residual controversy surrounding FACS-based assessment of microsphere uptake. PMID:24692642

Nagel, David; Behrendt, Jonathan M; Chimonides, Gwen F; Torr, Elizabeth E; Devitt, Andrew; Sutherland, Andrew J; Hine, Anna V

2014-06-01

253

The application of luminescence-kinetic methods in the study of the formation of lanthanide ion complexes in solution  

Microsoft Academic Search

The mechanisms of nonradiative transitions in lanthanide ions in solutions are discussed. The results of the use of this phenomenon in the study of the structures and stability constants of complexes of lanthanide ions in solutions are described. The possible uses of the nonradiative energy transfer between lanthanide ions in the determination of the stability constants of their complexes and

Valerii L Ermolaev; E B Sveshnikova

1994-01-01

254

Periodic behavior of lanthanide coordination within reverse micelles.  

PubMed

Trends in lanthanide(III) (Ln(III)) coordination were investigated within nanoconfined solvation environments. Ln(III) ions were incorporated into the cores of reverse micelles (RMs) formed with malonamide amphiphiles in n-heptane by contact with aqueous phases containing nitrate and Ln(III); both insert into pre-organized RM units built up of DMDOHEMA (N,N'-dimethyl-N,N'-dioctylhexylethoxymalonamide) that are either relatively large and hydrated or small and dry, depending on whether the organic phase is acidic or neutral, respectively. Structural aspects of the Ln(III) complex formation and the RM morphology were obtained by use of XAS (X-ray absorption spectroscopy) and SAXS (small-angle X-ray scattering). The Ln(III) coordination environments were determined through use of L(3)-edge XANES (X-ray absorption near edge structure) and EXAFS (extended X-ray absorption fine structure), which provide metrical insights into the chemistry across the period. Hydration numbers for the Eu species were measured using TRLIFS (time-resolved laser-induced fluorescence spectroscopy). The picture that emerges from a system-wide perspective of the Ln-O interatomic distances and number of coordinating oxygen atoms for the extracted complexes of Ln(III) in the first half of the series (i.e., Nd, Eu) is that they are different from those in the second half of the series (i.e., Tb, Yb): the number of coordinating oxygen atoms decrease from 9O for early lanthanides to 8O for the late ones--a trend that is consistent with the effect of the lanthanide contraction. The environment within the RM, altered by either the presence or absence of acid, also had a pronounced influence on the nitrate coordination mode; for example, the larger, more hydrated, acidic RM core favors monodentate coordination, whereas the small, dry, neutral core favors bidentate coordination to Ln(III). These findings show that the coordination chemistry of lanthanides within nanoconfined environments is neither equivalent to the solid nor bulk solution behaviors. Herein we address atomic- and mesoscale phenomena in the under-explored field of lanthanide coordination and periodic behavior within RMs, providing a consilience of fundamental insights into the chemistry of growing importance in technologies as diverse as nanosynthesis and separations science. PMID:23296409

Ellis, Ross J; Meridiano, Yannick; Chiarizia, Renato; Berthon, Laurence; Muller, Julie; Couston, Laurent; Antonio, Mark R

2013-02-18

255

Inductively coupled plasma atomic emission spectrometric determination of lanthanides and Y in various uranium hydrometallurgical products  

Microsoft Academic Search

An ICP-AES method for the analysis of trace amounts of lanthanides and yttrium in sodium or magnesium diuranate samples (yellow cake) and other beneficiation product generated during the uranium extraction process (hydrometallurgy) from its ores is described. Most of the matrix elements are removed by an initial oxalate precipitation of lanthanides using calcium as carrier. A solvent extraction procedure using

A. Premadas; P. K. Srivastava

2002-01-01

256

Sorption of lanthanide from aqueous organic solutions of nitric acid and nitrates  

SciTech Connect

We have studied the sorption of lanthanide radionuclides on the anion exchanger Dowex 1x8 from aqueous organic solutions of nitric acid and nitrates (ammonium, lithium, aluminum). As the organic solvents, we use ethanol, acetone, acetonitrile, and dimethylsulfoxide. We have shown that the change in sorbability of the lanthanides is due to the solvating donor-acceptor ability of the organic solvents.

Sheveleva, I.V.; Bogatyrev, I.O.

1988-05-01

257

Lanthanides in metallic nuclear fuels: Their behavior and methods for their control  

NASA Astrophysics Data System (ADS)

The thermodynamic and experimental basis is given for using dopant additives to bind lanthanides as intermetallic compounds in metallic nuclear fuels. Lanthanide fission products are a major factor in limiting the lifetime of the fuel, because they migrate to the fuel slug peripheral surface where they participate in fuel-cladding chemical interactions (FCCI) with the D9 or HT9 steel cladding. Lanthanide carryover in recycled metal fuels can accelerate FCCI, as recycled lanthanides would likely segregate from the fuel phase, putting the lanthanides in prompt contact with the cladding. In out-of-pile tests, the use of palladium was examined for binding the lanthanides, with palladium selected because of its known metallurgical properties in fuel-related systems and because of its known behavior in irradiated Experimental Breeder Reactor-II (EBR-II) fuels. Initial results confirmed that palladium may be expected to mitigate FCCI arising from lanthanides, and it has been recommended for in-pile tests. Transport phenomena responsible for lanthanide migration were also evaluated, and liquid-like behaviors were identified as being dominant. Liquid-like behaviors include transport with liquid metals, liquid metal solutions, and rapid surface transport of alloys/metals near their melting temperatures. The analysis led to establishing general criteria for selecting dopant additives and identifying tin, antimony, and tellurium as alternates for further testing.

Mariani, R. D.; Porter, D. L.; O'Holleran, T. P.; Hayes, S. L.; Kennedy, J. R.

2011-12-01

258

Lanthanide rare earths in stellar spectra with emphasis on chemically peculiar stars  

Microsoft Academic Search

The stellar abundance patterns of the lanthanide rare earths are investigated. Corrections to the ATLAS code of partition functions for the lanthanide rare earths are calculated on the basis of known energy levels. It is found that the ATLAS codes are generally accurate, except for Ce III. An increase of a factor of two in published cesium abundances is indicated

C. R. Cowley

1984-01-01

259

Hot-Pressed Silicon Nitride with Various Lanthanide Oxides as Sintering Additives.  

National Technical Information Service (NTIS)

The effects of addition of various lanthanide oxides and their mixture with Y2O3 on the sintering of Si3N4 were investigated. The addition of simple and mixed lanthanide oxides promoted the densification of Si3N4 in the hot-pressing at 1,800C under 300-40...

K. Ueno Y. Toibana

1984-01-01

260

Hot-Pressed Silicon Nitride with Various Lanthanide Oxides as Sintering Additives.  

National Technical Information Service (NTIS)

The effects of addition of various lanthanide oxides and their mixture with Y2O3 on the sintering of Si3N4 were investigated. The addition of simple and mixed lanthanide oxides promoted the densification of Si3N4 in hot-pressing at 1800 C under 300-400kg/...

K. Ueno Y. Toibana

1984-01-01

261

Room-temperature magnetic anisotropy of lanthanide complexes: A model study for various coordination polyhedra  

Microsoft Academic Search

The dependence of the room-temperature magnetic anisotropy ?? of lanthanide complexes on the type of the coordination polyhedron and on the nature of the lanthanide ion is quantitatively analyzed in terms of a model approach based on numerical calculations. The aim of this study is to establish general regularities in the variation of the sign and magnitude of the magnetic

Vladimir S. Mironov; Yury G. Galyametdinov; Arnout Ceulemans; Koen Binnemans

2002-01-01

262

Room-temperature magnetic anisotropy of lanthanide complexes: A model study for various coordination polyhedra  

Microsoft Academic Search

The dependence of the room-temperature magnetic anisotropy Deltachi of lanthanide complexes on the type of the coordination polyhedron and on the nature of the lanthanide ion is quantitatively analyzed in terms of a model approach based on numerical calculations. The aim of this study is to establish general regularities in the variation of the sign and magnitude of the magnetic

Vladimir S. Mironov; Yury G. Galyametdinov; Arnout Ceulemans; Christiane Görller-Walrand; Koen Binnemans

2002-01-01

263

Lanthanides in Metallic Nuclear Fuels: Their Behavior and Methods for Their Control  

SciTech Connect

The thermodynamic and experimental basis is given for using dopant additives to bind lanthanides as intermetallic compounds in metallic nuclear fuels. Lanthanide fission products are a major factor in limiting the lifetime of the fuel, because they migrate to the fuel slug peripheral surface where they participate in fuel-cladding chemical interactions (FCCI) with the steel cladding. Lanthanide carryover in recycled metal fuels can accelerate FCCI, as recycled lanthanides would likely segregate from the fuel phase, putting the lanthanides in prompt contact with the cladding. In out-of-pile tests we examined the use of Pd for binding the lanthanides, with Pd selected because of its known metallurgical properties in fuel related systems and because of its known behavior in irradiated EBR-II fuels. Initial results confirmed that palladium may be expected to mitigate FCCI arising from lanthanides, and it has been recommended for in-pile tests. We also evaluated transport phenomena responsible for lanthanide migration, and identified liquid-like behaviors as being dominant. Liquid-like behaviors include transport with liquid metals, liquid metal solutions, and rapid surface transport of alloys/metals near their melting temperatures. The analysis led to establishing general criteria for selecting alternate dopant additives, and identifying Sn, Sb, and Te as alternates for further testing.

Robert D. Mariani; Douglas L. Porter; Thomas P. O'Holleran; Steven L. Hayes; J. Rory Kennedy

2011-12-01

264

21 CFR 866.3355 - Listeria spp. serological reagents.  

Code of Federal Regulations, 2010 CFR

...immunofluorescent reagents) used to identify Listeria spp. directly from clinical...bacteria belonging to the genus Listeria, and provides epidemiological...caused by these microorganisms. Listeria monocytogenes, the most common...

2009-04-01

265

21 CFR 866.3355 - Listeria spp. serological reagents.  

Code of Federal Regulations, 2010 CFR

...immunofluorescent reagents) used to identify Listeria spp. directly from clinical...bacteria belonging to the genus Listeria, and provides epidemiological...caused by these microorganisms. Listeria monocytogenes, the most common...

2010-04-01

266

21 CFR 866.3550 - Salmonella spp. serological reagents.  

Code of Federal Regulations, 2010 CFR

...serological reagents. (a) Identification. Salmonella spp...clinical specimens. The identification aids in the diagnosis of salmonellosis caused by bacteria belonging to the genus...high grade fever (âenteric feverâ), severe...

2009-04-01

267

21 CFR 866.3550 - Salmonella spp. serological reagents.  

Code of Federal Regulations, 2010 CFR

...serological reagents. (a) Identification. Salmonella spp...clinical specimens. The identification aids in the diagnosis of salmonellosis caused by bacteria belonging to the genus...high grade fever (âenteric feverâ), severe...

2010-04-01

268

21 CFR 866.3145 - Coxsackievirus serological reagents.  

Code of Federal Regulations, 2010 CFR

...coxsackievirus in serum. Additionally, some of these reagents consist of coxsackievirus antisera conjugated with a fluorescent dye that are used to identify coxsackievirus from clinical specimens or from tissue culture isolates derived...

2009-04-01

269

21 CFR 866.3110 - Campylobacter fetus serological reagents.  

Code of Federal Regulations, 2010 CFR

...Identification. Campylobacter fetus serological reagents are devices that consist of antisera conjugated with a fluorescent dye used to identify Campylobacter fetus from clinical specimens or cultured isolates derived from clinical...

2010-04-01

270

21 CFR 866.3110 - Campylobacter fetus serological reagents.  

Code of Federal Regulations, 2010 CFR

...Identification. Campylobacter fetus serological reagents are devices that consist of antisera conjugated with a fluorescent dye used to identify Campylobacter fetus from clinical specimens or cultured isolates derived from clinical...

2009-04-01

271

21 CFR 866.3370 - Mycobacterium tuberculosis immunofluorescent reagents.  

Code of Federal Regulations, 2013 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3370 Mycobacterium tuberculosis immunofluorescent...

2013-04-01

272

Polymeric reagents for derivatizations in micellar electrokinetic chromatography.  

PubMed

A polymer immobilized o-nitrobenzophenone reagent was prepared for analysis of amine drugs in micellar electrokinetic chromatography (MEKC). A model compound, propylamine, was used to characterize the reagent's performance in MEKC. Derivatizations were performed on the CE instrument with reagent in the sample vial. The yielded derivative was directly sampled from the reaction mixture, and directly injected onto the MEKC system. The derivatization reagent was also applied to the derivatization of n-alkyl amine mixtures and amino acids. The method was validated for adamantanamine in urine and in plasma by single-blind spike analysis. Precisions and accuracies for all samples were less than 6.0% for urine samples and 10% for plasma samples. The procedure was a direct injection technique requiring minimal sample preparation for the analysis of drugs in biofluids. PMID:7841764

Szulc, M; Krull, I S

1994-01-01

273

Reactivity of N-phenyl silylated ketenimines with electrophilic reagents  

Microsoft Academic Search

We report the reactivity of new C? silylated ketenimines (4, 5, 6) and lithiated-silylated ketenimine 3 leasily generated from lithiated S-methyl-N-phenyl-trimethylsilylethanimidothioate 2] toward electrophilic reagents. Reactions of these ketenimines with strong electrophilic reagents such as sulfanyl chloride (PhSCl) gave access to new sulfanylated ketenimines. With less reactive species [benzenesulfinyl chloride (PhS(O)Cl), p-toluenesulfonyl chloride, trimethylhalosilanes, diisopropyl chlorophosphate, acetyl chloride and propylene

Christophe Fromont; Serge Masson

1999-01-01

274

Detection of lanthanides and actinides in solutions based on laser-induced luminescence and chemiluminescence  

NASA Astrophysics Data System (ADS)

This work is devoted to applications of the time-resolved laser- induced luminescence spectroscopy and time-resolved laser-induced chemiluminescence spectroscopy for detection of lanthanides and actinides. The limit of detection (LOD) of some lanthanides and actinides in solutions by the time-resolved laser luminescence spectroscopy is up to 10-13 mole/liter. Unfortunately, Pu, Np, and some U compounds do not produce luminescence in solutions, but when excited by laser radiation, they can induce chemiluminescence. The characteristics of chemiluminescence induced by excited lanthanide and actinide complexes in solutions are considered. A key problem of chemiluminescence application for lanthanide and actinide detection in solutions is the increase of the detection selectivity. This problem can be solved by using the multistep schemes of chemiluminescence excitation. It is shown that the time-resolved luminescence laser spectroscopy and chemiluminescence laser spectroscopy can be successfully used for detection of lanthanides and actinides in solutions.

Izosimov, I. N.; Firsin, N. G.; Gorshkov, N. G.; Nekhoroshkov, S. N.

2014-06-01

275

IUPAC-NIST Solubility Data Series. 85. Transition and 12-14 Main Group Metals, Lanthanide, Actinide, and Ammonium Halates  

NASA Astrophysics Data System (ADS)

This paper is the fourth and final volume in the halate solubility series. The solubility data for halates of transition metals, lanthanides, actinides, ammonium, and metallic elements of the main groups 12-14 are reviewed. Where appropriate, binary, ternary, and multicomponent systems are critically evaluated. Most of the solubility results were obtained in water or aqueous solutions of electrolytes. The solubility in organic solvents and aqueous-organic solvent mixtures is also collected in this volume. All these data were critically examined for their reliability. The best values were selected on the basis of critical evaluations and presented in tabular form. Fitting equations and graphical plots are also provided. When numerical data were not reported in an original publication, they were read out from figures and digitized by the compilers. The quantities, units, and symbols used in this volume are in accord with IUPAC recommendations. We always reported the original data and, if necessary, transferred them into the IUPAC recommended units and symbols. The literature on the solubility data was researched through 2002. The halates of these metals play a role in industrial processes. For example, some halates are essential as catalysts, heat stabilizers, and blanching reagents for manufacturing polymer products such as textiles and resins. Some iodates are used in pyrotechnic compounds for weather modification and colored smoke generation. The nonlinear halate crystals are important in construction of optical devices.

Miyamoto, Hiroshi

2008-06-01

276

Crystal growth of inter-lanthanide La Ln?O 3 ( Ln? = Y, Ho–Lu) perovskites from hydroxide fluxes  

Microsoft Academic Search

In this article, we report the growth of single crystals of the inter-lanthanide series LaLn?O3 (Ln?=Y, Ho–Lu) using molten hydroxide fluxes. Inter-lanthanide oxides, LnLn?O3 (where Ln and Ln?=lanthanides) typically crystallize in the A-, B- or C-Ln2O3 or in the ABO3 perovskite structure types, depending on the relative sizes of the lanthanide cations involved. The inter-lanthanide oxides, LaLn?O3 (Ln?=Y, Ho–Lu), reported

M. Bharathy; Adam H. Fox; S. J. Mugavero; H.-C. zur Loye

2009-01-01

277

Biological Rhythms and Shift Work: Shift Work and Nursing.  

National Technical Information Service (NTIS)

Shift work within the nursing profession is examined. The authors first address the prevalence of shift work in nursing, its patterns, and the evidence for dissatisfaction with shift work. Next, the consequences of shift work are discussed, such as family...

C. S. Weisman

1989-01-01

278

A series of three-dimensional architectures constructed from lanthanide-substituted polyoxometalosilicates and lanthanide cations or lanthanide-organic complexes as linkers.  

PubMed

Six 3D architectures based on lanthanide-substituted polyoxometalosilicates, KLn[(H(2)O)(6)Ln](2)[(H(2)O)(4)LnSiW(11)O(39)](2)·nH(2)O (Ln = La 1, n = 42; Ce 2, n = 40), H[(H(2)O)(6)Nd](2)[(H(2)O)(7)Nd][(H(2)O)(4)NdSiW(11)O(39)][(H(2)O)(3)NdSiW(11)O(39)]·13H(2)O (3), H(2)K(2)[(Hpic)(H(2)O)(5)Ln](2)[(H(2)O)(4)LnSiW(11)O(39)](2)·nH(2)O (Ln = La 4, n = 18.5; Ce 5, n = 35; Nd 6, n = 36; Hpic = 4-picolinic acid), have been synthesized and characterized by elemental analysis, IR and UV-vis spectroscopy, TG analysis, powder X-ray diffraction and single crystal X-ray diffraction. Compounds 1 and 2 are isostructural, built up of lanthanide-substituted polyoxoanions [{(H(2)O)(4)Ln(SiW(11)O(39))}(2)](10-) linked by Ln(3+) cations to form a 3D open framework with 1D channels. The polyoxoanion [{(H(2)O)(4)Ln(SiW(11)O(39))}(2)](10-) consists of two ?(1)-type mono-Ln-substituted Keggin anions. When Nd(3+) ion was used instead of La(3+) or Ce(3+) ions, compound 3 with a different structure was obtained, containing two kinds of polyoxoanions [{(H(2)O)(4)Nd(SiW(11)O(39))}(2)](10-) and [{(H(2)O)(3)Nd(SiW(11)O(39))}(2)](10-) which are connected together by Nd(3+) ions to yield a 3D framework. When 4-picolinic acid was added to the reaction system of 1-3, isostructural compounds 4-6 were obtained, constructed from the polyoxoanions [{(H(2)O)(4)Ln(SiW(11)O(39))}(2)](10-) linked by picolinate-chelated lanthanide centers to form a 3D channel framework. From a topological viewpoint, the 3D nets of 1, 2, 4, 5 and 6 exhibit a (3,6)-connected rutile topology, whereas the 3D structure of 3 possesses a rare (3,3,6,10)-connected topology. The magnetic properties of 2, 3, 5 and 6 have been studied by measuring their magnetic susceptibilities in the temperature range 2-300 K. PMID:22641140

An, Haiyan; Zhang, Hua; Chen, Zhaofei; Li, Yangguang; Liu, Xuan; Chen, Hao

2012-07-21

279

Strategies to prepare and use functionalized organometallic reagents.  

PubMed

Polyfunctional zinc and magnesium organometallic reagents occupy a central position in organic synthesis. Most organic functional groups are tolerated by zinc organometallic reagents, and Csp(2)-centered magnesium organometallic reagents are compatible with important functional groups, such as the ester, aryl ketone, nitro, cyano, and amide functions. This excellent chemoselectivity gives zinc- and magnesium-organometallic reagents a central position in modern organic synthesis. Efficient and general preparations of these organometallic reagents, as well as their most practical and useful reactions, are presented in this Perspective. As starting materials, a broad range of organic halides (iodides, bromides, and also to some extent chlorides) can be used for the direct insertion of magnesium or zinc powder; the presence of LiCl very efficiently promotes such insertions. Alternatively, aromatic or heterocyclic bromides also undergo a smooth bromine-magnesium exchange when treated with i-PrMgCl·LiCl. Alternative precursors of zinc and magnesium reagents are polyfunctionalized aryl and heteroaryl molecules, which undergo directed metalations with sterically hindered TMP bases (TMP = 2,2,6,6-tetramethylpiperide) of magnesium and zinc. This powerful C-H functionalization method gives access to polyfunctional heterocyclic zinc and magnesium reagents, which undergo efficient reactions with numerous electrophiles. The compatibility of the strong TMP-bases with BF3·OEt2 (formation of frustrated Lewis pairs) dramatically increases the scope of these metalations, giving for example, a practical access to magnesiated pyridines and pyrazines, which can be used as convenient building blocks for the preparation of biologically active molecules. PMID:24697240

Klatt, Thomas; Markiewicz, John T; Sämann, Christoph; Knochel, Paul

2014-05-16

280

The low-temperature heat capacity of some lanthanide zirconates  

Microsoft Academic Search

The heat capacities of the lanthanide zirconates Gd2Zr2O7 and Eu2Zr2O7 with pyrochlore structure were measured by adiabatic calorimetry and the hybrid adiabatic relaxation method in the temperature range (0.3 to 400) K. A thermal anomaly was observed for Gd2Zr2O7 below T=15 K. From the measurements the thermodynamic functions of Gd2Zr2O7 and Eu2Zr2O7 were determined. By combining our results with the

S. Lutique; R. J. M. Konings; J.-C. Krupa; A. C. G. van Genderen; J. C. van Miltenburg; F. Wastin

2004-01-01

281

Centrifugal atomization of lanthanide materials for cryogenic coolers  

SciTech Connect

Until recently, Pb was the preferred heat exchanger matrix material used in low temperature cryocoolers; however, the heat capacity of Pb drops drastically below {approximately}15K and new matrix materials based on the lanthanide elements have been developed. These materials magnetically order at low temperatures and the entropy change associated with ordering contributes to the materials` heat capacities. The drawback to widespread use of lanthanide intermetallic compounds in cryocoolers has been the difficulty in manufacturing high-quality particulates. The purpose of this project was to develop a technique for producing high-quality powders of lanthanide metals and lanthanide intermetallic compounds for use in cryocooler heat exchangers. A series of atomization experiments was performed using Er{sub 3}Ni, Nd, Nd{sub 3}Ni, and (Er{sub 0.5}Nd{sub 0.5}){sub 3}Ni. Atomization of these materials resulted in particles ranging from mostly spherical to extremely flattened. Analyses of size distributions for the experiments indicate that increased atomization disk speed and superheat result in smaller mean particle diameters and narrower size distributions. Chemical analyses of the atomized powders indicate that the CA/RQB technique produces particulate with much lower interstitial contamination than other techniques. The Er{sub 3}Ni and Nd{sub 3}Ni powders were predominantly of the desired phase and the (Er{sub 0.5}Nd{sub 0.5}){sub 3}Ni powder had one major and possibly three minor phases. The solidification morphology is typically fine dendritic or cellular with finer microstructure spacings near the particle surfaces. The Er{sub 3}Ni powders have higher heat capacities than gas atomized powders reported in literature. The heat capacity of Nd{sub 3}Ni has a peak which does not degrade dramatically with processing. The (Er{sub 0.5}Nd{sub 0.5}){sub 3}Ni material has a higher heat capacity compared to Er{sub 3}Ni, Nd{sub 3}Ni, and Nd at temperatures above 10K.

Osborne, M.G.

1994-01-04

282

Status of the lanthanides and actinides in the periodic table  

SciTech Connect

In extended discussions and correspondence with Ekkehard Fluck, the author was made aware of a problem with the Periodic Table, i.e., which element should be shown in the main table as the representative of the lanthanide series and the actinide series. In earlier discussion, he came to the conclusion that lanthanum and actinium are not the elements which should appear, but rather lutetium and lawrencium are more appropriate for inclusion in their place. This paper will attempt to justify the reasons for the above conclusions. 4 refs.

Holden, N.E.

1985-01-01

283

A luminescent mixed-lanthanide metal-organic framework thermometer.  

PubMed

A luminescent mixed lanthanide metal-organic framework approach has been realized to explore luminescent thermometers. The targeted self-referencing luminescent thermometer Eu(0.0069)Tb(0.9931)-DMBDC (DMBDC = 2, 5-dimethoxy-1, 4-benzenedicarboxylate) based on two emissions of Tb(3+) at 545 nm and Eu(3+) at 613 nm is not only more robust, reliable, and instantaneous but also has higher sensitivity than the parent MOF Tb-DMBDC based on one emission at a wide range from 10 to 300 K. PMID:22352469

Cui, Yuanjing; Xu, Hui; Yue, Yanfeng; Guo, Zhiyong; Yu, Jiancan; Chen, Zhenxia; Gao, Junkuo; Yang, Yu; Qian, Guodong; Chen, Banglin

2012-03-01

284

Lanthanide Trifluoride Thin Films: Structure, Composition, and Optical Properties  

NASA Astrophysics Data System (ADS)

This study characterizes thin films of eleven lanthanide trifluorides which are potentially useful for optical applications. The natural and controlled transparency and real refractive index of single layers of these trifluorides are examined and accompanied by studies of composition and crystal structure of the films which are made by conventional, high temperature, and ion-assisted thermal evaporation. Additionally, since these particular fluoride compounds provide an excellent opportunity for doing so, the mechanisms active in film modification through high temperature and ion-assisted thermal evaporation are explored.

Lingg, Linda Jeanne

1990-01-01

285

Electrical resistivity of liquid lanthanides using charge hard sphere system  

NASA Astrophysics Data System (ADS)

In the present paper, we have studied electrical resistivity (?) of liquid lanthanides. To describe the structural information, the structure factor S(q) due to the charged hard sphere (CHS) reference systems is used along with our newly constructed model potential. To see the influence of exchange and correlation effect on the electrical resistivity (?) have used different local field correction functions like Hartree (H), Sarkar et al (S) and Taylor (T). Lastly we conclude that the proper choice of the model potential along with local field correction function plays a vital role to the study of the electrical resistivity (?).

Sonvane, Y. A.; Thakor, P. B.; Jani, A. R.

2013-06-01

286

Gibbs energies of formation of hydroxides of lanthanides and yttrium  

Microsoft Academic Search

The pH values of the formation of hydrates in solutions of yttrium(III), cerium(III), samarium(III), europium(III), erbium(III),\\u000a and ytterbium(III) were determined by conductometric titration. The solubility products and Gibbs energies of formation for\\u000a hydroxides for the elements listed were calculated. The average Gibbs energy of dissolution for lanthanide hydroxides was\\u000a found to be approximately 149.83 ± 0.90 kJ\\/mol. The Gibbs energies

D. E. Chirkst; O. L. Lobacheva; I. V. Berlinskii

2010-01-01

287

Making Shifts toward Proficiency  

ERIC Educational Resources Information Center

The Leading for Mathematical Proficiency (LMP) Framework (Bay-Williams et al.) has three components: (1) The Standards for Mathematical Practice; (2) Shifts in classroom practice; and (3) Teaching skills. This article briefly describes each component of the LMP framework and then focuses more in depth on the second component, the shifts in…

McGatha, Maggie B.; Bay-Williams, Jennifer M.

2013-01-01

288

Style Shift in Translation  

ERIC Educational Resources Information Center

The phenomenon of style shift in translated texts is ascribed mainly to textual incompatibility in terms of rhetorical asymmetry and divergence at the formality level. Mandatory shifts result from a systematic dissimilarity between the source language and the target language in terms of the underlying system of syntax, semantics and rhetorical…

Al-Qinai, Jamal

2009-01-01

289

Leachability of decontamination reagents from cement waste forms  

SciTech Connect

Brookhaven National Laboratory, in order to provide technical information needed by the US Nuclear Regulatory Commission to evaluate the adequacy of near-surface disposal of decontamination wstes, has begun to study the leachability of organic reagents from solidified simulated decontamination wastes. Laboratory-scale cement waste forms containing EDTA, picolinic acid or simulated LOMI decontamination reagent were leach tested. Samples containing an organic reagent on either mixed bed ion-exchange resins or anion exchange resins were tested. A fixed interval leach procedure was used, as well as the standard procedure ANS 16.1. The leachability indices measured for the release of the acid from resin/cement composites are: 10.1 for EDTA on mixed bed resins; 9.1 for picolinic acid on mixed bed resins; 9.2 for picolinic acid on anion exchange resins; 8.8 for picolinic acid in forms containing simulated low oxidation metallic ion (LOMI) reagent on mixed bed resins and 8.7 for picolinic acid in forms containing simulated LOMI reagent on anion exchange resins. The leachability indices measured varied with leach time and the data indicate that the release mechanism may not be simply diffusion controlled. 5 references, 2 tables.

Piciulo, P.L.; Davis, M.S.; Adams, J.W.

1984-11-26

290

A simple procedure for crystallization of the Schiff reagent.  

PubMed

Formation of crystals in Schiff reagents prepared from SO2 gas previously has been reported either soon after preparation, using high dye concentrations and heating, or after long periods of storage at room temperature. With the first type of procedure only a low yield of crystals accompanied by dye precipitation was obtained. Crystallization without dye precipitation took place if the reagent, prepared with pararosaniline base or chloride in a saturated SO2 solution, was stored for a sufficient time at room temperature in partly filled flasks. These crystals remained colorless if washed with acid alcohol after being separated by filtration. Schiff reagents layered with paraffin oil or supplemented with 0.1 M hydroquinone took much longer to crystallize, suggesting that crystallization is promoted by the partial oxidation of sulfurous acid to sulfuric acid. A high yield of crystals can be obtained at room temperature after as little as 24 hr by adding 0.04 M of H2SO4 to a Schiff reagent prepared with 2% pararosaniline chloride in a saturated SO2 solution. A Schiff reagent prepared with only 0.2% of these crystals gives an intense staining in the Feulgen and in the Periodic acid-Schiff reactions. PMID:8393350

Galassi, L

1993-05-01

291

Finding new equilibria: Directed synthesis of lanthanide materials via sodium azide mediated pathways  

NASA Astrophysics Data System (ADS)

This dissertation covers the synthesis and characterization of three unique classes of lanthanide materials produced exclusively by the addition of sodium azide (NaN3) into solution based lanthanide reactions. The products were achieved through transmetallation and redox reactions between rare earth chalcogenolate reagents (Lnx(EPh)y), NaN 3 and elemental chalcogenides (E = O, S, Se, Te). The products displayed atypical structural and physical properties including; unique coordination geometries, high nuclearities, tunable detonation/deflagration, strong NIR emissions, and unexpected magnetic ordering behaviors. The introduction of NaN3, Na2O, Cd, elemental Se and Te into Ln (EPh)2 and Ln(EPh)3 pyridine (py) solutions led to the production of (py) 2Na2(EPh)2 and 5 structurally distinct azide encapsulated rare earth clusters; (Py) 10Sm6O2(N3)16Na2, (py)8Ln6O2(N3)12(SePh) 2, (py)10Ln6O2(Se2) 2(N3)10 (Ln=Er, Ho), and (py)16Sm 8Se(O2)Na2(Te2)6(N 3)8. Each system was encapsulated by a variety of azide bridging moieties, while exhibiting a [Ln]/[N3] dependent correlation with detonation and deflagration temperatures. The inclusion of NaN3 in Ln(SePh)3 pyridine solutions with elemental Se, led to the discovery of the (py)16Ln17 NaSe18(SePh)16; (Ln= Ce, Pr, and Nd). Emission studies of the Nd17 analogue, revealed a 35% quantum efficiency for the 4F3/2 - 4I11/2 transition (1070 nm emission), and a near solid state emission intensity for the 4F3/2 ? 4I15/2 transition (1822 nm emission). The novel Eu(EPh)4Na2•2DME; (E=S,Se), specimens were synthesized by the combination of Eu(EPh)2 with NaN3 in dimethoxyethane (DME). The europium coordination sphere was solvent free and resembles the coordinations of europium monochalcogenides (EuE). Comparative structural analysis and magnetic susceptibility studies of the Eu3+ product, ((py)6Eu2(mu4-S 2)2(OC6F5)2) revealed paramagnetic ordering at low temperature for Eu(EPh)4Na2•2DME; (E=S,Se), while ferrimagnetic ordering was found for ((py)6Eu2(mu4-S 2)2(OC6F5)2). All materials exhibited antiferromagnetic ordering above 50 K, while a Curie temperature of 18.0 K was determined for ((py)6Eu2(mu2-S 2)2-(OC6F5)2).

Moore, Brian Freeman

292

New reagents for coal desulfurization. Final technical report, September 1, 1990--August 31, 1991  

SciTech Connect

The primary goal of this project was development and exploration of potential new desulfurization reagents for the removal of ``organic sulfur`` from Illinois coals by mild chemical methods. Potential new desulfurization reagents were investigated using organic sulfur compounds of the types thought to be present in coals. Reagents included low-valent metal complexes based on nickel and on iron as well as possible Single Electron Transfer reagents. Soluble coal extracts served as second generation model compounds during this reagent development project.

Buchanan, D.H.; Kalembasa, S.; Olson, D.; Wang, S.; Warfel, L.

1991-12-31

293

Measurement of high acidity using a renewable-reagent fiber optic sensor  

Microsoft Academic Search

The renewable-reagent sensor concept was initially developed to address shortcomings in fiber optic chemical sensors dependent on immobilized, reversible reagents to produce analyte specific responses. The renewable-reagent sensor incorporates semi-selective membranes, analyte specific reagents, and remote spectroscopic detection to extract selective responses. While renewable-reagent fiber optic sensors have been demonstrated for a number of chemical sensing applications, the transfer of

K. J. Kuhn; J. T. Dyke

1995-01-01

294

Basic understanding of the lanthanide related upconversion emissions  

NASA Astrophysics Data System (ADS)

With abundant energy levels of 4f electron configurations, trivalent lanthanide ions (Ln3+) are endowed with unique and fascinating luminescent properties. Inheriting the native transition behaviour of the lanthanide ions, Ln3+ based nanomaterials have aroused great interest for a wide range of applications, including lighting and displays, optical fibers and amplifiers, responsive luminescent stains for biomedical analysis, in vivo and in vitro imaging, and enhancement for silicon solar cell devices. It should be noted that the application depends completely on the corresponding luminescent behaviour. To deepen the understanding of the luminescent mechanism is important for the developing of the field and the design of new Ln3+ based luminescent materials toward applications. In this review, we focused mainly on the recent developments on upconversion (UC) emission studies. Firstly, the emphasis was put on the introduction of basic luminescent properties of Ln3+ with f-f transitions, and then the corresponding mechanisms and properties of UC emission were discussed in detail, the potential researches with respect to UC mechanisms and properties were finally outlined.

Dong, Hao; Sun, Ling-Dong; Yan, Chun-Hua

2013-06-01

295

Monodisperse lanthanide fluoride nanocrystals: synthesis and luminescent properties.  

PubMed

Three types of high-quality, monodisperse lanthanide fluoride colloidal nanocrystals (NCs) including LnF(3) (Ln = La-Pr), NaLnF(4) (Ln = Sm-Er), and Na(5)Ln(9)F(32) (Ln = Tm-Lu) with two crystal phases (hexagonal and cubic) and a rich variety of morphologies have been synthesized in high boiling organic solvents oleic acid and 1-octadecene, via a thermal decomposition pathway. The as-synthesized NCs were well characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FT-IR), and photoluminescence (PL) spectra, respectively. It is found that the as-synthesized NCs consist of monodisperse nanoparticles with diverse shapes and narrow size distribution, which can easily disperse in nonpolar cyclohexane solvent. Additionally, a possible mechanism of NC nucleation and growth has been proposed. The results reveal that the formation of monodisperse NCs closely correlates with the inherent nature of lanthanide series from La to Lu. Under 980 nm NIR excitation, as-synthesized Yb(3+)/Ln(3+) (Ln = Er, Tm, Ho)-doped NaGdF(4) and Na(5)Lu(9)F(32) colloidal NCs show the respective characteristic up-conversion (UC) emissions of Er(3+), Tm(3+), and Ho(3+), which are promising for applications in biolabels, bioimaging, displays, and other optical technologies. PMID:22409422

Li, Xingbo; Gai, Shili; Li, Chunxia; Wang, Dong; Niu, Na; He, Fei; Yang, Piaoping

2012-04-01

296

Raman spectroscopic study of trivalent lanthanides in concentrated aqueous solutions  

NASA Astrophysics Data System (ADS)

The Raman spectra in the region of the O-H stretching vibration band are used to investigate the effect of lanthanide (III) ions on liquid water structure in concentrated aqueous solutions of CeCl3 and GdCl3 (C~0.5÷3 M). The differential spectra, derived from the consequent Raman spectra, have reflected the substantial discrepancy between the spectra of lanthanide (III) salt solutions and pure water as well as the spectra of standard LiCl (C~1.5÷9M) solutions. The new sharp bands (vmax ~ 3180÷3190 cm-1) and (vmax~3360 cm-1), observed in the differential spectra, are assumed to two types of aqua-ions: Ln3+[H2O]mH2On and Ln3+[H2O]mClp- having a difference in the 2nd coordination sphere. The discrepancy, observed in the spectra of the equmolar CeCl3 and GdCl3 aqueous solutions, is interpreted as a result of the different hydration numbers and ion radiuses of Ce3+aq and Gd3+aq.

Tsvirko, M.; Svetashev, A.

2011-04-01

297

Structural rearrangement through lanthanide contraction in dinuclear complexes.  

PubMed

A new series of lanthanide complexes was synthesized, and the geometry and preliminary magnetic measurements of the complexes were explored. The specific ligand used (N'-(2-hydroxy-3-methoxybenzylidene)benzhydrazide) (H2hmb) was synthesized using a Schiff-base approach and was employed due to the presence of a coordination pocket that is able to accommodate magnetically selective lanthanide ions. The series can be divided into two groups that are categorized by a drastic structural rearrangement. The first group, Type I, contains six analogous complexes with the formula [M(III)2(Hhmb)3(NCS)3]·2MeOH·py (M = Y 1, Eu 2, Gd 3, Tb 4, Dy 5, Ho 6), while the second group, Type II, contains two dinuclear complexes with formula [M(III)2(Hhmb)2(NCS)4(MeOH)2] (M = Er 7, and Yb 8). Single-crystal X-ray analysis revealed that all M(III) ions in Type I exhibit monocapped distorted square antiprismatic geometries, while those of Type II exhibit distorted dodecahedron geometry. The direct current and alternating current magnetic measurements were carried out on all complexes, with 5, 7, and 8 exhibiting slow relaxation of the magnetization under an applied optimum dc field. Furthermore, complex 8 is the first example of a dinuclear Yb-based single-molecule magnet showing field-dependent multiple relaxation processes. PMID:24499030

Hutchings, Amy-Jayne; Habib, Fatemah; Holmberg, Rebecca J; Korobkov, Ilia; Murugesu, Muralee

2014-02-17

298

Synthesis and properties of mixed lanthanide chromite perovskites  

SciTech Connect

Calcium-substituted lanthanum chromites were synthesized using a mixed lanthanide precursor composed primarily of La, Nd, Ce, and Pr. The thermal and electrical properties of these materials were measured and compared to similar chromites synthesized with lanthanum nitrate. The presence of Nd and Pr in the chromite resulted in a lowering of the thermal expansion coefficient and an increase in the temperature necessary to attain full density. Arrhenius plots of electrical conductivity were nonlinear with an inflection at temperatures between 625 and 750 C, indicating an increase in the carrier concentration with temperature. The increase in carrier concentration was consistent with the reduction of Ce{sup 4+} to ce{sup 3+}, resulting in a corresponding increase in Cr{sup 4+} in order to preserve electrical neutrality. The presence of both tri- and tetravalent Ce was substantiated using dilatometry measurements and X-ray photoelectron spectroscopy. The mixed lanthanide precursor is a possible low cost alternative for the synthesis of rare earth chromites for applications such as interconnects in solid oxide fuel cells.

Armstrong, T.R.; Stevenson, J.W.; Hasinska, Katarzyna; McCready, D.E. [Pacific Northwest National Lab., Richland, WA (United States). Materials and Chemical Sciences Dept.

1998-12-01

299

Energetic lanthanide complexes: coordination chemistry and explosives applications  

NASA Astrophysics Data System (ADS)

Metals are generally added to organic molecular explosives in a heterogeneous composite to improve overall heat and energy release. In order to avoid creating a mixture that can vary in homogeneity, energetic organic molecules can be directly bonded to high molecular weight metals, forming a single metal complex with Angstrom-scale separation between the metal and the explosive. To probe the relationship between the structural properties of metal complexes and explosive performance, a new series of energetic lanthanide complexes has been prepared using energetic ligands such as NTO (5-nitro-2,4-dihydro-1,2,4-triazole-3-one). These are the first examples of lanthanide NTO complexes where no water is coordinated to the metal, demonstrating novel control of the coordination environment. The complexes have been characterized by X-ray crystallography, NMR and IR spectroscopies, photoluminescence, and sensitivity testing. The structural and energetic properties are discussed in the context of enhanced blast effects and detection. Cheetah calculations have been performed to fine-tune physical properties, creating a systematic method for producing explosives with 'tailor made' characteristics. These new complexes will be benchmarks for further study in the field of metalized high explosives.

Manner, V. W.; Barker, B. J.; Sanders, V. E.; Laintz, K. E.; Scott, B. L.; Preston, D. N.; Sandstrom, M.; Reardon, B. L.

2014-05-01

300

Purification of lanthanides for double beta decay experiments  

SciTech Connect

There are several potentially double beta active isotopes among the lanthanide elements. However, even high purity grade lanthanide compounds contain {sup 238}U, {sup 226}Ra and {sup 232,228}Th typically on the level of ? (0.1 - 1) Bq/kg. The liquid-liquid extraction technique was used to remove traces of U, Ra and Th from CeO{sub 2}, Nd{sub 2}O{sub 3} and Gd{sub 2}O{sub 3}. The radioactive contamination of the samples before and after the purification was tested by using ultra-low-background HPGe ? spectrometry at the underground Gran Sasso National Laboratories of the INFN (Italy). After the purification the radioactive contamination of gadolinium oxide by Ra and Th was decreased at least one order of magnitude. The efficiency of the approach to purify cerium oxide from Ra was on same level, while the radioactive contamination of neodymium sample before and after the purification is below the sensitivity of analytical methods. The purification method is much less efficient for chemically very similar radioactive elements like lanthanum, lutetium and actinium. R and D of the methods to remove the pollutions with improved efficiency is in progress.

Polischuk, O. G. [Institute for Nuclear Research, MSP 03680 Kyiv, Ukraine and INFN, Section of Rome, La Sapienza, I-00185 Rome (Italy)] [Institute for Nuclear Research, MSP 03680 Kyiv, Ukraine and INFN, Section of Rome, La Sapienza, I-00185 Rome (Italy); Barabash, A. S. [Institute of Theoretical and Experimental Physics, 117259 Moscow (Russian Federation)] [Institute of Theoretical and Experimental Physics, 117259 Moscow (Russian Federation); Belli, P. [INFN, Section of Rome Tor Vergata, I-00133 Rome (Italy)] [INFN, Section of Rome Tor Vergata, I-00133 Rome (Italy); Bernabei, R. [INFN, Section of Rome Tor Vergata, I-00133 Rome, Italy and Department of Physics, University of Rome Tor Vergata, I-00133 Rome (Italy)] [INFN, Section of Rome Tor Vergata, I-00133 Rome, Italy and Department of Physics, University of Rome Tor Vergata, I-00133 Rome (Italy); Boiko, R. S.; Danevich, F. A.; Mokina, V. M.; Poda, D. V.; Tretyak, V. I. [Institute for Nuclear Research, MSP 03680 Kyiv (Ukraine)] [Institute for Nuclear Research, MSP 03680 Kyiv (Ukraine); Cappella, F.; Incicchitti, A. [INFN, Section of Rome La Sapienza, I-00185 Rome, Italy and Department of Physics, University of Rome La Sapienza, I-00185 Rome (Italy)] [INFN, Section of Rome La Sapienza, I-00185 Rome, Italy and Department of Physics, University of Rome La Sapienza, I-00185 Rome (Italy); Cerulli, R.; Laubenstein, M.; Nisi, S. [INFN, Gran Sasso National Laboratories, I-67100 Assergi (Aq) (Italy)] [INFN, Gran Sasso National Laboratories, I-67100 Assergi (Aq) (Italy)

2013-08-08

301

Design and synthesis of chelating diamide sorbents for the separation of lanthanides  

SciTech Connect

A nanoporous sorbent designed around chelating iminodiacetamide (“IDA-Amide”) moiety was made on mesoporous silica (MCM-41) and evaluated for lanthanide separations (Ce3+, Nd3+, Eu3+, Gd3+, and Lu3+). The effects of solution pH on lanthanide binding were studied, as well as sorption kinetics, and competition from other metal ions. The IDA-Amide SAMMS® demonstrated an interesting difference in the kinetics of sorption of the lanthanide ions in the order of Lu3+ > Eu3+ > Gd3+ > Nd3+ > Ce3+ . The close proximity of the ligands in the IDA-Amide SAMMS® may allow for multiple metal-ligand interactions (“macromolecular chelation”).

Fryxell, Glen E.; Chouyyok, Wilaiwan; Rutledge, Ryan D.

2011-06-01

302

Preparation and Purification of Zinc Sulphinate Reagents for Organic Synthesis  

PubMed Central

SUMMARY The present protocol details the synthesis of zinc bis(alkanesulphinate)s that can be used as general reagents for the formation of radical species. The zinc sulphinates described herein have been generated from the corresponding sulphonyl chlorides by treatment with zinc dust. The products may be used crude, or a simple purification procedure may be performed to minimize incorporation of water and zinc chloride. Elemental analysis has been conducted in order to confirm the purity of the zinc sulphinate reagents; reactions with caffeine have also been carried out to verify the reactivity of each batch that has been synthesized. Although the synthesis of the zinc sulphinate salts generally proceeds within 3 h, workup can take up to 24 h and purification can take up to 3 h. Following the steps in this protocol would enable the user to generate a small toolkit of zinc sulphinate reagents over the course of one week.

O'Hara, Fionn; Baxter, Ryan D.; O'Brien, Alexander G.; Collins, Michael R.; Dixon, Janice A.; Fujiwara, Yuta; Ishihara, Yoshihiro; Baran, Phil S.

2014-01-01

303

Beyond antibodies: new affinity reagents to unlock the proteome.  

PubMed

Antibodies have been the workhorse reagents of protein capture and quantification since their 1959 debut in the RIAs developed by Yalow and Berson. However, there are technical challenges to the use of antibodies in highly multiplexed arrays aimed at measuring hundreds or even thousands of proteins at one time. We describe here a recently developed class of synthetic protein-binding reagents (slow off-rate modified aptamer). We discuss the chemical makeup and protein binding specifications of slow off-rate modified aptamer reagents, compare them to traditional aptamers and antibodies, briefly describe the novel proteomic assay that takes advantage of their unique properties, and provide several examples of their multiple applications to biomarker discovery and validation across a range of biomedical science questions. PMID:24395722

Lollo, Bridget; Steele, Fintan; Gold, Larry

2014-03-01

304

Evaluation of novel derivatisation reagents for the analysis of oxysterols.  

PubMed

Oxysterols are oxidised forms of cholesterol that are intermediates in the synthesis of bile acids and steroid hormones. They are also ligands to nuclear and G protein-coupled receptors. Analysis of oxysterols in biological systems is challenging due to their low abundance coupled with their lack of a strong chromophore and poor ionisation characteristics in mass spectrometry (MS). We have previously used enzyme-assisted derivatisation for sterol analysis (EADSA) to identify and quantitate oxysterols in biological samples. This technique relies on tagging sterols with the Girard P reagent to introduce a charged quaternary ammonium group. Here, we have compared several modified Girard-like reagents and show that the permanent charge is vital for efficient MS(n) fragmentation. However, we find that the reagent can be extended to include sites for potential stable isotope labels without a loss of performance. PMID:24525124

Crick, Peter J; Aponte, Jennifer; Bentley, T William; Matthews, Ian; Wang, Yuqin; Griffiths, William J

2014-04-11

305

Evaluation of novel derivatisation reagents for the analysis of oxysterols  

PubMed Central

Oxysterols are oxidised forms of cholesterol that are intermediates in the synthesis of bile acids and steroid hormones. They are also ligands to nuclear and G protein-coupled receptors. Analysis of oxysterols in biological systems is challenging due to their low abundance coupled with their lack of a strong chromophore and poor ionisation characteristics in mass spectrometry (MS). We have previously used enzyme-assisted derivatisation for sterol analysis (EADSA) to identify and quantitate oxysterols in biological samples. This technique relies on tagging sterols with the Girard P reagent to introduce a charged quaternary ammonium group. Here, we have compared several modified Girard-like reagents and show that the permanent charge is vital for efficient MSn fragmentation. However, we find that the reagent can be extended to include sites for potential stable isotope labels without a loss of performance.

Crick, Peter J.; Aponte, Jennifer; Bentley, T. William; Matthews, Ian; Wang, Yuqin; Griffiths, William J.

2014-01-01

306

A red-shifted fluorescent substrate for aldehyde dehydrogenase.  

PubMed

Selection of cells positive for aldehyde dehydrogenase (ALDH) activity from a green-fluorescent background is difficult with existing reagents. Here we report a red-shifted fluorescent substrate for ALDH, AldeRed 588-A, for labelling viable ALDH(pos) cells. We demonstrate that AldeRed 588-A successfully isolates ALDH(hi) human haematopoietic stem cells from heterogeneous cord blood mononuclear cells. AldeRed 588-A can be used for multicolour applications to fractionate ALDH(pos) cells in the presence of green fluorophores including the ALDEFLUOR reagent and cells expressing enhanced green-fluorescent protein (eGFP). AldeRed 588-A stains ALDH(pos) murine pancreatic centroacinar and terminal duct cells, as visualized using fluorescent microscopy. AldeRed588-A provides a useful tool to select stem cells or study ALDH within a green-fluorescent background. PMID:24759454

Minn, Il; Wang, Haofan; Mease, Ronnie C; Byun, Youngjoo; Yang, Xing; Wang, Julia; Leach, Steven D; Pomper, Martin G

2014-01-01

307

Mechanism of acylphosphatase inactivation by Woodward's reagent K.  

PubMed Central

The organ common-type (CT) isoenzyme of acylphosphatase is inactivated by Woodward's reagent K (WRK) (N-ethyl-5-phenylisoxazolium-3'-sulphonate) at pH6.0. The inactivation reaction follows apparent pseudo first-order kinetics. The dependence of the reciprocal of the pseudo first-order kinetic constant (kobs) on the reciprocal WRK concentration reveals saturation kinetics, suggesting that the WRK forms a reversible complex with the enzyme before causing inactivation. Competitive inhibitors, such as inorganic phosphate and ATP, protect the enzyme from WRK inactivation, suggesting that this reagent acts at or near to the enzyme active site. The reagent-enzyme adduct, which elicits a strong absorption band with lambdamax at 346 nm, was separated from unreacted enzyme by reverse phase HPLC and the modified protein was cleaved with endoproteinase Glu-C to produce fragments. The HPLC fractionation gave two reagent-labelled peptides (peak 1 and peak 2) that were analysed by ion-spray MS and sequenced. The former is VFFRKHTQAE (residues 20-29 of human CT acylphosphatase) and the latter IFGKVQGVFFRKHTQAE (residues 13-29). MS demonstrated that both peptides are WRK adducts. A fragment ion with m/z of 1171, which is present in the mass spectrum of peak 1, has been identified as a WRK adduct of the peptide fragment 20-26. The lambdamax at 346 nm of WRK adduct suggests that the modified residue is His-25. Five recombinant enzymes mutated in residues included in the 20-29 polypeptide stretch have been produced. Analysis of their reactivities with WRK demonstrates that His-25 is the molecular target of the reagent as its modification causes the inactivation of the enzyme. Since both His-25-->Gln and His-25-->Phe mutants maintain high catalytic activity, we suggest that the observed enzyme inactivation is caused by the reagent (covalently bound to His-25), which shields the active site.

Paoli, P; Fiaschi, T; Cirri, P; Camici, G; Manao, G; Cappugi, G; Raugei, G; Moneti, G; Ramponi, G

1997-01-01

308

alpha-Bromo-4-amino-3-nitroacetophenone, a new reagent for protein modification. Modification of the methionine-290 residue of porcine pepsin.  

PubMed Central

A new coloured reagent for protein modification, alpha-bromo-4-amino-3-nitroacetophenone (NH2BrNphAc), was synthesized. The reagent was found to alkylate specifically the methionine-290 residue of porcine pepsin below pH 3 at 37 degrees C, which lead to a 45% decrease of enzyme's activity towards haemoglobin. The effect of this reagent as well as that of other phenacyl bromides on the activity of pepsin appeared to be a result of steric hindrance caused by the attachment of bulky reagent residue to the edge of the cleft harbouring the enzyme active site. Only marginal reaction with the co-carboxy group of aspartic acid-315 was found under the above conditions. More pronounced esterification of carboxy groups (up to one residue per enzyme molecule) occurred when the pH was shifted to 5.2. The latter modification had no noticeable effect on enzyme activity, thus disproving a previously held assumption that pepsin inactivation by phenacyl bromide is due to the carboxy-group esterification. alpha-Bromo-4-amino-3-nitroacetophenone forms derivatives with characteristic u.v. spectra when it reacts with methionine, histidine, aspartic and glutamic acid residues, and may be recommended as a reagent for protein modification.

Tarasova, N I; Lavrenova, G I; Stepanov, V M

1980-01-01

309

Decontamination of MDA Reagents for Single Cell Whole Genome Amplification  

PubMed Central

Single cell genomics is a powerful and increasingly popular tool for studying the genetic make-up of uncultured microbes. A key challenge for successful single cell sequencing and analysis is the removal of exogenous DNA from whole genome amplification reagents. We found that UV irradiation of the multiple displacement amplification (MDA) reagents, including the Phi29 polymerase and random hexamer primers, effectively eliminates the amplification of contaminating DNA. The methodology is quick, simple, and highly effective, thus significantly improving whole genome amplification from single cells.

Woyke, Tanja; Sczyrba, Alexander; Lee, Janey; Rinke, Christian; Tighe, Damon; Clingenpeel, Scott; Malmstrom, Rex; Stepanauskas, Ramunas; Cheng, Jan-Fang

2011-01-01

310

A Kalman filter for poisoned reagent feed streams  

SciTech Connect

A Kalman filter was designed for a reagent feed system to reduce the noise in an analyzer measurement used to initiate shutdowns of the system under accident conditions. The filter's performance was validated by simulating plant conditions and also in a plant test. The standard deviation in steady state analyzer measurements, processed as a 36-second moving average of one second readings, was reduced by 33% using the Kalman filter estimate. Additionally, unmeasured leaks to the system were estimated by the filter providing a means of incipient failure detection against dilution of the reagent vessel's contents. 10 refs., 13 figs.

Griffin, C.D.; Croson, D.V.

1988-09-01

311

Premarket evaluation of commercial toxoplasmosis indirect fluorescent-antibody reagents.  

PubMed Central

The quality of commercial toxoplasmosis indirect fluorescent-antibody reagents was evaluated over a 6-year period. Seven manufacturers voluntarily submitted their products for evaluation in the Center for Disease Control Premarket Evaluation Program. Each product was tested in accordance with the Center for Disease Control performance and labeling specifications and evaluation methods. Only 49% of all of the products tested met the Center for Disease Control requirements. Performance criteria are outlined, and suggestions are offered to assist laboratorians in obtaining toxoplasmosis indirect fluorescent-antibody reagents of high quality.

Durham, T M; Colvin, H M

1978-01-01

312

Chemical-Shift Concertina.  

National Technical Information Service (NTIS)

The phase-alternated experiment in liquids, a multiple-pulse NMR experiment capable of scaling chemical shifts, is examined theoretically and experimentally. The theory of the experiment is worked out using both the average-Hamiltonian and classical magne...

J. D. Ellett J. S. Waugh

1969-01-01

313

Climate science: Shifting storms  

NASA Astrophysics Data System (ADS)

An analysis of historical storm data reveals that the average latitude at which tropical cyclones attain their maximum intensity has undergone a pronounced shift towards the poles over the past three decades. See Letter p.349

Ramsay, Hamish

2014-05-01

314

Auditory Attention Shifting.  

National Technical Information Service (NTIS)

This research effort measured the spectral and temporal dynamics of human auditory attentional control, concentrating on the requirements for efficient shifting of auditory attention within the frequency spectrum of normal human hearing.

A. Reeves B. Scharf

2008-01-01

315

Our World: Fluid Shift  

NASA Video Gallery

Learn about the circulatory system and how gravity aids blood flow in our bodies here on Earth. Find out how NASA flight surgeons help the astronauts deal with the fluid shift that happens during s...

316

Sintese e caracterizacao de complexos de picratos de lantanideos (III) com a 4-picolina-N-oxido (4-picNO). (Synthesis and characterization of lanthanide picrate complexes with 4-picoline-N-oxide (4-pic N O)).  

National Technical Information Service (NTIS)

The lanthanide picrate complexes with 4-picoline-N-oxide were obtained from ethanolic solutions of the hydrated lanthanide picrate and the ligand. The lanthanide content was determined by complexometric titration with EDTA. Carbon, Nitrogen and Hydrogen w...

E. M. Silva

1991-01-01

317

Complexation of lanthanides and actinides by acetohydroxamic acid  

Microsoft Academic Search

Acetohydroxamic acid (AHA) has been proposed as a suitable reagent for the complexant-based, as opposed to reductive, stripping of plutonium and neptunium ions from the tributylphosphate solvent phase in advanced PUREX or UREX processes designed for future nuclear-fuel reprocessing. Stripping is achieved by the formation of strong hydrophilic complexes with the tetravalent actinides in nitric acid solutions. To underpin such

R. J. Taylor; S. I. Sinkov; G. R. Choppin

2008-01-01

318

Molecular Electronic Shift Registers  

NASA Technical Reports Server (NTRS)

Molecular-scale shift registers eventually constructed as parts of high-density integrated memory circuits. In principle, variety of organic molecules makes possible large number of different configurations and modes of operation for such shift-register devices. Several classes of devices and implementations in some specific types of molecules proposed. All based on transfer of electrons or holes along chains of repeating molecular units.

Beratan, David N.; Onuchic, Jose N.

1990-01-01

319

Preparation of n,n-dialkylcarbamato lanthanide complexes by extraction of lanthanide ions from aqueous solution into hydrocarbons.  

PubMed

Lanthanides are easily extracted as N,N-dibutylcarbamato complexes from aqueous solutions of their chlorides into heptane solutions of dibutylamine saturated with CO2. The products are recovered in high yields and are soluble in hydrocarbons. The derivatives [Ln(O2CNBu2)3]n [Ln = Nd (1), Eu (2), Tb (3)], [NH2Bu2]2[Ln4(CO3)(O2CNBu2)12] [Ln = Tb (4), Sm (5), Eu (6)], and [Sm4(CO3)(O2CNBu2)10], 7, have thus been obtained. The crystal and molecular structure of 4 has been solved; the samarium and europium complexes 5 and 6 were found to be isostructural. Mass spectra of the complexes 1-3, 4, and 7 (in MeCN/toluene) reveal that equilibria are present in solution. Compound 2 has been reacted in toluene with NHBz2 in the presence of CO2 affording [NH2Bz2][Eu(O2CNBz2)4], 8, through a ligand exchange process. By thermal treatment, 8 afforded [Eu(O2CNBz2)3]n, 9. With a similar procedure [Sm(O2CNBz2)3]n, 10, was obtained from 5. According to the photoluminescence study carried out on solid samples of 2, 4, 5, 7, and 8, the metal centered f-f transitions represent the only effective way to induce lanthanide luminescence in these complexes. PMID:24779510

Armelao, Lidia; Belli Dell'Amico, Daniela; Biagini, Paolo; Bottaro, Gregorio; Chiaberge, Stefano; Falvo, Paola; Labella, Luca; Marchetti, Fabio; Samaritani, Simona

2014-05-19

320

Systematic study on the structures of salen type lanthanide complexes tuned by lanthanide contraction and corresponding luminescence.  

PubMed

Two types of N,N'-bis(salicylidene)-1,3-propanediamine (H2L) lanthanide complexes, viz. [Ln(NO3)3(H2L)2]·0.2CH3OH [Ln = La (1), Ce (2) and Pr (3)] and [Ln(NO3)3(H2L)2]2·CH2Cl2·CH3OH [Ln = Nd (4), Sm (5), Eu (6), Gd (7), Tb (8) and Yb (9)], have been isolated by reactions of H2L with Ln(NO3)3·6H2O. X-ray crystallographic and PXRD analysis reveal that 1-3 are isomorphic possessing a novel one-dimensional (1D) ladder-like double-chain structure. Complexes 4-9 are isostructural exhibiting a discrete dinuclear structure. Luminescent analysis reveals the lanthanide ion and ligand-centered co-luminescence for 5, 6 and 8, which are attributed to the incomplete energy transfer from the triplet state of H2L to the resonance energy level of the corresponding Ln(iii) ion. Further, the characteristic near infrared (NIR) luminescence of Nd(iii) and Yb(iii) ions for complexes 4 and 9 have been revealed. PMID:23660709

Zou, Xiaoyan; Li, Mingjie; Yan, Pengfei; Zhang, Juwen; Hou, Guangfeng; Li, Guangming

2013-07-14

321

Discrimination of enantiomers of alpha-amino acids by chiral derivatizing reagents from trans-1,2-diaminocyclohexane.  

PubMed

New chiral derivatizing reagents (CDAs) derived from trans-1,2-diaminocyclohexane, having an electron-deficient aromatic substituent (either an aromatic imide or 3,5-dinitrobenzamide) and rigid structure (either an amide or a urea linker), are reported. Significant shift differences of diastereotopic protons in the 1H NMR signals are observed for enantiomers of suitably protected alpha-amino acids, linked to CDA by a covalent bond. A simple, general model rationalizing the observed enantiomer discrimination and based on semiempirical conformational search is presented. PMID:17600850

Kaik, Magdalena; Gajewy, Jadwiga; Grajewski, Jakub; Gawronski, Jacek

2008-03-01

322

Lanthanide-functionalized nanoparticles as MRI and luminescent probes for sensing and/or imaging applications.  

PubMed

The combination of lanthanides and nanoparticles to develop new hybrid nanomaterials has become a highly topical area of research in the field of sensing, biomedical imaging, drug delivery, etc. However, these novel nanomaterials have to be carefully designed to ensure that the unique properties conveyed by each component, i.e., lanthanide ions and nanoparticles, are maximized and not negatively affected by one another. In this Forum Article, the main advances in the design of lanthanide-based nanoparticles will be discussed, with the first part focusing on the design of gadolinium(III)-based nanoparticles and their use as magnetic resonance imaging agents. The second part will then describe the main and most recent designs of luminescent lanthanide-based nanoparticles and their applications as sensors or imaging agents, with a special emphasis on our contribution to this area. PMID:24354305

Comby, Steve; Surender, Esther M; Kotova, Oxana; Truman, Laura K; Molloy, Jennifer K; Gunnlaugsson, Thorfinnur

2014-02-17

323

Studies on the Vapour Phase Hydrolysis of Some Lanthanide and Actinide (III) Bromides.  

National Technical Information Service (NTIS)

The equilibrium constants of the vapour phase hydrolysis of actinide and lanthanide bromides were determined for different temperature levels. The tribromides are hydrolyzed into oxide bromides while releasing hydrogen bromide. The equilibrium constants o...

R. Gueldner

1981-01-01

324

Lanthanide salts solutions: representation of osmotic coefficients within the binding mean spherical approximation.  

PubMed

Osmotic coefficients of aqueous solutions of lanthanide salts are described using the binding mean spherical approximation (BIMSA) model based on the Wertheim formalism for association. The lanthanide(III) cation and the co-ion are allowed to form a 1-1 ion pair. Hydration is taken into account by introducing concentration-dependent cation size and solution permittivity. An expression for the osmotic coefficient, derived within the BIMSA, is used to fit data for a wide variety of lanthanide pure salt aqueous solutions at 25 degrees C. A total of 38 lanthanide salts have been treated, including perchlorates, nitrates, and chlorides. For most solutions, good fits could be obtained up to high ionic strengths. The relevance of the fitted parameters has been discussed, and a comparison with literature values has been made (especially the association constants) when available. PMID:16863190

Ruas, Alexandre; Moisy, Philippe; Simonin, Jean-Pierre; Bernard, Olivier; Dufrêche, Jean-François; Turq, Pierre

2005-03-24

325

The TRUSPEAK Concept: Combining CMPO and HDEHP for Separating Trivalent Lanthanides from the Transuranic Elements  

SciTech Connect

Combining octyl(phenyl)-N,N-diisobutyl-carbamoylmethyl-phosphine oxide (CMPO) and bis-(2-ethylhexyl) phosphoric acid (HDEHP) into a single process solvent for separating transuranic elements from liquid high-level waste is explored. Co-extraction of americium and the lanthanide elements from nitric acid solution is possible with a solvent mixture consisting of 0.1-M CMPO plus 1-M HDEHP in n-dodecane. Switching the aqueous-phase chemistry to a citrate-buffered solution of diethylene triamine pentaacetic acid (DTPA) allows for selective stripping of americium, separating it from the lanthanide elements. Potential strategies for managing molybdenum and zirconium (both of which co-extract with americium and the lanthanides) have been developed. The work presented here demonstrates the feasibility of combining CMPO and HDEHP into a single extraction solvent for recovering americium from high-level waste and its separation from the lanthanides.

Lumetta, Gregg J.; Gelis, Artem V.; Braley, Jenifer C.; Carter, Jennifer C.; Pittman, Jonathan W.; Warner, Marvin G.; Vandegrift, George F.

2013-04-08

326

Progress Report on Synthesis and Chemistry of Yttrium and Lanthanide Metal Complexes.  

National Technical Information Service (NTIS)

The overall objective of this research project is to develop the basic chemistry of complexes of the lanthanide metals which will allow the design and synthesis of materials with unique chemical, physical, and catalytic properties. This report summarizes ...

W. J. Evans

1999-01-01

327

Mixed Ligand Chelate Extraction of Lanthanides with N-M-Trifluoromethylbenzoylphenylhydroxylamine Systems.  

National Technical Information Service (NTIS)

A study of the equilibrium extraction behavior of a series of representative tervalent lanthanide ions, Pr, Eu and Yb, was carried out with chloroform solutions containing N-benzoylphenylhydroxylamine, N-m-trifluoromethylbenzoylphenylhydroxylamine (HL) ei...

S. Inoue C. F. Ordonez H. Freiser

1985-01-01

328

Magneto-photoluminescence in lanthanide-bearing endohedral metallofullerenes with various cage symmetries  

NASA Astrophysics Data System (ADS)

Taken as a family, endohedral metallofullerenes (EMF) nanomaterials provide opportunities for exquisite functional tunability at the nanoscale, enabling a wide range of synthetic nanoparticles with diverse sizes, symmetries, electronic, optical and, especially, magnetic properties. In particular, metallofullerenes incarcerating lanthanide ions will permit endohedral luminescence due to the 4f optically-active electrons being uninvolved in the stabilizing charge transfer between the endohedral guest and cage. In addition, if those lanthanide ions possess optical transitions beyond the absorption onset of the cage, a well-defined optical spectrum may be observed for the metallofullerene system. In this talk, several magneto-optical and time-resolved studies at high magnetic fields on lanthanide-based EMFs with different cage symmetries will be presented, where the residual magnetic degeneracies in the lanthanide ion energy levels are lifted and observed in the optical spectrum with magnetic field strengths in excess of 10 T.

Merritt, Travis; Dorn, Harry; Khodaparast, Giti A.; McGill, Steve

2012-02-01

329

Reaction of enamines with trifluoromethyl containing carbonyl reagents  

Microsoft Academic Search

The reaction of linear push–pull enamines bearing a methyl group at the ?-position with a set of trifluoromethylated carbonyl compounds was investigated. It has been found that the reaction proceeds at the methyl group of the enamines. The first computational study of the reaction between push–pull enamines and strong electrophilic reagents was reported. Out of three pathways considered DFT and

Dmitriy A. Sibgatulin; Tatyana E. Shubina; Aleksandr N. Kostyuk; Dmitriy M. Volochnyuk; Reinhard Schmutzler; Peter G. Jones; Aleksandr M. Pinchuk

2010-01-01

330

Tritiated alumina serves as reagent for self-labeling analysis  

NASA Technical Reports Server (NTRS)

Tritiated alumina, prepared by exchange of the surface hydroxyl groups with tritiated water, is a suitable reagent for exchange-labeling of specific compounds in low concentrations prior to chromatographic analysis. In a chromatographic column, it detects and measures submicrogram quantities of material.

Erenrich, E. H.; Klein, P. D.

1967-01-01

331

The Clinical Proteomic Technologies for Cancer | Reagent Opportunities  

Cancer.gov

In efforts to provide an open data platform for affinity reagents NCI’s Antibody Characterization Program has begun to utilize Material Cooperative Research and Development Agreements (M-CRADAs) through SAIC-Frederick, Inc so that commercial vendors can use the antibody characterization pipeline.

332

CPTC expand scope of Reagents and Resources Core  

Cancer.gov

Whether in determining if a women is pregnant or not by measuring human chorionic gonadotropin or determining whether someone is HIV positive, antibodies and other affinity reagents play a key role both in diagnostic decision making and advancing the research field.

333

Activated Monomers and Nucleophilic Reagents in Addition and Polymerization Reactions  

Microsoft Academic Search

A number of examples of addition and polymerization reactions is presented with special emphasis on the chemical behaviors of activated monomers and\\/or activated nucleophilic reagents. Lithium alkoxyethanolate forms a complex with lithium alkyl. Spectroscopic studies showed this complex to possess agent-separated ion pairs. The nature of the complex is characterized by the enhanced reactivity of styrene in the copolymerization reaction

T. Tsuruta

1975-01-01

334

Kinetics of Solid State Reactions With Fractal Reagent  

Microsoft Academic Search

In the present research we theoretically studied the kinetics of nucleation-limited solid state reactions as influenced by the fractal properties of solid reagent. We consider the model of equal-sized primary particles assembled in fractal cluster. The geometry of such an object is assumed to be described solely by its fractal dimension D and by upper (Rmax) and lower (Rmin) cutoffs

S. V. Kalinin; A. A. Vertegel; N. N. Oleynikov; Yu. D. Tretyakov

1998-01-01

335

[Recommendations for the control of equipment, reagents and consumables].  

PubMed

This article describes the dispositions to apply according to the requirements of the EN ISO 15189 standard for selection, purchasing and management of equipment, reagents and consumables in the medical laboratory. Recommendations are developed for acceptance testing, calibration and metrological traceability, maintenance and repair, adverse incident reporting and records to keep. PMID:23765022

Daunizeau, A

2013-06-01

336

Carbanions as Intermediates in the Formation of Grignard Reagents  

Microsoft Academic Search

The reaction between certain aryl bromides RBr having substituents with group 14 elements and magnesium in THF to form the corresponding Grignard reagents RMgBr were found to be accompanied by unusual migrations of the group 14 functionality; it partially exchanges position with that of the original aryl bromide function. This migration is purely intramolecular for organosilicon derivatives but both intra-

Gerard P. M. van Klink; Henricus J. R. de Boer; Gerrit Schat; Otto S. Akkerman; Friedrich Bickelhaupt; Anthony L. Spek

2002-01-01

337

Synthesis of sulfones from organozinc reagents, DABSO, and alkyl halides.  

PubMed

Organozinc reagents react with the SO2 surrogate DABSO, and the resulting zinc sulfinate salts are alkylated in situ to afford sulfones. This transformation has a broad scope and is compatible with a wide range of structural motifs of medicinal chemistry relevance including nitrile, secondary carbamates, and nitrogen-containing heterocycles. PMID:24308287

Rocke, Benjamin N; Bahnck, Kevin B; Herr, Michael; Lavergne, Sophie; Mascitti, Vincent; Perreault, Christian; Polivkova, Jana; Shavnya, Andrei

2014-01-01

338

Cleavable trifunctional biotin reagents for protein labelling, capture and release.  

PubMed

Trifunctional biotin reagents incorporating cleavable linkers are evaluated for their usage in protein enrichment. A linker based on the Dde protecting group leads to efficient release of protein targets under mild conditions. It additionally contains a masked trypsin cleavage site, which eliminates the majority of the tag during tryptic digestion. PMID:23648945

Yang, Yinliang; Verhelst, Steven H L

2013-06-14

339

Microarray immunoassay for phenoxybenzoic acid using polymer-functionalized lanthanide oxide nanoparticles as fluorescent labels  

Microsoft Academic Search

Fluorescent properties and low production cost makes lanthanide oxide nanoparticles attractive labels in biochemistry. Nanoparticles with different fluorescent spectra were produced by doping of oxides such as Y2O3 and Gd2O3 with different lanthanide ions (Eu, Tb, Sm) giving the possibility for multicolor labeling. Protein microarrays have the potential to play a fundamental role in the miniaturization of biosensors, clinical immunological

Mikaela Nichkova; Dosi Dosev; Shirley J. Gee; Bruce D. Hammock; Ian M. Kennedy

2005-01-01

340

Solid state reactions in highly dispersed single and mixed lanthanide oxide–SiO 2 systems  

Microsoft Academic Search

This paper summarizes our previous studies on the interaction of highly dispersed lanthanide oxides (La, Ce, Pr, Nd and Lu) with amorphous silica and presents new data on the Ce0.5Yb0.5O1.75–SiO2 system. It is shown that at temperatures above 800°C, chemical reaction between lanthanide oxide and silica may occur leading to formation of silicate phases with unusual structure not observed for

Ma?gorzata A. Ma?ecka; Leszek K?pi?ski

341

Novel luminescent lanthanide complexes covalently linked to a terpyridine-functionalized silica network  

Microsoft Academic Search

Novel luminescent organic–inorganic hybrid materials consisting of lanthanide (Eu3+, Tb3+) complexes covalently bonded to a silica-based network have been obtained by a sol–gel approach. A new monomer has been synthesized by the thiol-ene photopolymerization between ?-mercaptopropyltrimethoxysilane and 4?-allyloxy-2,2?:6?,2?-terpyridine. The monomer is afterward submitted to complexation with lanthanide ions and used as the siloxane network precursor. FT-IR, DR, SEM, luminescence spectra

Bi-Hai Tong; Shuan-Jin Wang; Jian Jiao; Fu-Ri Ling; Yue-Zhong Meng; Biao Wang

2007-01-01

342

Extraction of lanthanides from acidic solution using tributyl phosphate modified supercritical carbon dioxide  

Microsoft Academic Search

The feasibility of using supercritical carbon dioxide as a substitute extraction solvent in nuclear reprocessing was tested by the extraction of lanthanide ions from acidic solution. Lanthanides were extracted from 6 M HNO[sub 3]-3 M LiNO[sub 3] solutions using tributyl phosphate- (TBP-) modified CO[sub 2]. Synergistic effects were also investigated using a combination of thenoyltrifluoroacetone (TTA) and TBP-modified CO[sub 2

K. E. Laintz; E. Tachikawa

1994-01-01

343

Key features of the Talspeak and similar trivalent actinide-lanthanide partitioning processes  

SciTech Connect

As closing of the nuclear-fuel cycle via the suite of UREX processes under development in the U.S. progresses, the Trivalent Actinide-Lanthanide Separation by Phosphorus Extractants and Aqueous Komplexants (TALSPEAK) process has been selected as the baseline process for partition of trivalent actinides away from fission-product lanthanides. In this report, selected features of the chemistry of the TALSPEAK process and the limited parallel information on other TALSPEAK-like processes are discussed. (author)

Nash, Kenneth L. [Washington State University, Chemistry Department, P.O. Box 644630, Pullman, WA 99164-4630 (United States)

2008-07-01

344

Crystal growth of inter-lanthanide La Ln'O 3 ( Ln' = Y, Ho-Lu) perovskites from hydroxide fluxes  

NASA Astrophysics Data System (ADS)

In this article, we report the growth of single crystals of the inter-lanthanide series La Ln'O 3 ( Ln' = Y, Ho-Lu) using molten hydroxide fluxes. Inter-lanthanide oxides, LnLn'O 3 (where Ln and Ln' = lanthanides) typically crystallize in the A-, B- or C-Ln2O3 or in the ABO 3 perovskite structure types, depending on the relative sizes of the lanthanide cations involved. The inter-lanthanide oxides, La Ln'O 3 ( Ln' = Y, Ho-Lu), reported herein were determined to crystallize in the orthorhombic ( Pnma) perovskite-type structure. A discussion on the effect of cation radii on the resultant crystal structure for La Ln'O 3 ( Ln' = Y, Ho-Lu) and other reported inter-lanthanide oxides is presented herein.

Bharathy, M.; Fox, Adam H.; Mugavero, S. J.; zur Loye, H.-C.

2009-03-01

345

Separation and direct UV detection of lanthanides complexed with cupferron by capillary electrophoresis.  

PubMed

Separation and detection of lanthanides by capillary zone electrophoresis in the presence of cupferron (N-nitroso-N-phenylhydroxylamine) as UV absorbing complexing agent were investigated. The resolution of partially complexed positively charged cupferron complexes is improved by using a buffer ligand competing with cupferron for metal ions. When hydroxyisobutyric acid (HIBA) is used as buffer and competing ligand, it provides complete separation of all 14 lanthanides with good peak shapes. An on-column separation of 14 lanthanides was achieved in only 7 min using 0.1 mmol/l cupferron, 15 mmol/1 HIBA at pH 4.9. The separation efficiencies for the optimum separation condition are between 77,000 and 208,000 theoretical plates. Determination of lanthanide complexes was performed by direct UV detection at 210 nm. Detection limits (signal-to-noise ratio=3) are ca. 0.24-0.47 microg/ml for lanthanides. Under optimum conditions, the complete separation of thorium and uranium from mixed lanthanides was achieved. PMID:11105870

Oztekin, N; Erim, F B

2000-10-20

346

Formation and stability of lanthanide complexes and their encapsulation into polymeric microspheres  

SciTech Connect

The complexation of lanthanides (Ln) with dicarbonyl compounds (acetylacetone, acac; ethyl acetoacetate; 3-ethyl-2,4-pentanedione; 2,4-hexanedione; 3-methyl-2,4-pentanedione; and diethyl malonate) was investigated using a potentiometric titration technique. The ability of a dicarbonyl compound to complex with the lanthanide elements was greatly dependent on its pK{sub a} and on the pH of the titrated solution. Selected lanthanide complexes (Ln complexes) were incorporated into spherical poly(L-lactic acid)(PLA) matrices and irradiated in a nuclear reactor with neutrons to produce short-lived high-energy {Beta}-particle-emitting radioisotopes. The lanthanides investigated (Ho, Dy, Sm, and La) were chosen on the basis of their physical and nuclear properties. A transition element (Re) was also studied. The small decrease in the ionic radii of the lanthanides with increasing atomic number led to (a) greater ability to extract and complex from an aqueous solution with complexing agents, (b) larger formation and stability constants for the Ln complexes, (c) increased solubility of the Ln complexes in chloroform, and (d) increase in the maximum percent incorporation of the stable lanthanides in PLA spheres. Ho(aca) was found to be the most promising candidate of the complexes studied on the basis of the above observations and due to the favorable physical properties of {sup 165}Ho and nuclear properties of {sup 166}Ho. 21 refs., 5 figs., 4 tabs.

Mumper, R.J.; Jay, M. [Univ. of Kentucky, Lexington, KY (United States)

1992-10-15

347

Supercritical fluid extraction of lanthanides with fluorinated [beta]diketones and tributyl phosphate  

SciTech Connect

Trivalent lanthanide ions (La[sup 3+], Eu[sup 3+], and Lu[sup 3+]) in solid materials can be effectively extracted by methanol-modified carbon dioxide containing a suitable fluorinated [beta]-diketone (such as HFA, TTA, or FOD) at 60[degree]C and 150 atm. Addition of a small amount of water to the solid samples can significantly increase the extraction efficiency. Tributyl phosphate (TBP) shows a strong positive synergistic effect with the fluorinated [beta]-diketones for the extraction of the lanthanides in supercritical CO[sub 2] without methanol modifier. Quantitative extraction of the lanthanides (92-98%) from sand or a cellulose-based solid material can be achieved using a mixture of TBP and one of the fluorinated [beta]-diketones in neat CO[sub 2] at 60[degree]C and 150 atm. The synergistic effect depends on the structure and fluorine substitution in the [beta]-diketone. In soil matrix, TBP+HFA are more effective than TBP+TTA or TBP+FOD for lanthanide extraction in supercritical CO[sub 2]. Without fluorine substitution, as in the case of acetylacetone, the positive synergistic extraction of lanthanides with TBP is negligible. With the mixed-ligand approach, high efficiencies of lanthanide extraction from aqueous solutions by neat CO[sub 2] can also be accomplished. 14 refs., 4 tabs.

Lin, Y.; Wai, C.M. (Univ. of Idaho, Moscow, ID (United States))

1994-07-01

348

Gold Coated Lanthanide Phosphate Nanoparticles for Targeted Alpha Generator Radiotherapy  

SciTech Connect

Targeted radiotherapies maximize cytotoxicty to cancer cells. In vivo generators such as 225Ac, which emits four particles in its decay chain, can significantly amplify the radiation dose delivered to the target site. However, renal dose from unbound 213Bi escaping during the decay process limits the dose of 225Ac that can be administered. Traditional chelating moieties are unable to sequester the radioactive daughters because of the high recoil energy from alpha particle emission. To counter this, we demonstrate that an engineered multilayered nanoparticle-antibody conjugate can both deliver radiation and contain the decay daughters of the in vivo -generator 225Ac while targeting biologically relevant receptors. These multi-shell nanoparticles combine the radiation resistance of crystalline lanthanide phosphate to encapsulate and contain 225Ac and its radioactive decay daughters, the magnetic properties of gadolinium phosphate for easy separation, and established surface chemistry of gold for attachment of nanoparticles to targeting antibodies.

McLaughlin, Mark F [ORNL; Woodward, Jonathan [ORNL; Boll, Rose Ann [ORNL; Wall, Jonathan [University of Tennessee, Knoxville (UTK); Rondinone, Adam Justin [ORNL; Kennel, Steve J [ORNL; Mirzadeh, Saed [ORNL; Robertson, David J. [University of Missouri

2013-01-01

349

Supramolecular luminescent lanthanide dimers for fluoride sequestering and sensing.  

PubMed

Lanthanide complexes (Ln=Eu, Tb, and Yb) that are based on a C2 -symmetric cyclen scaffold were prepared and characterized. The addition of fluoride anions to aqueous solutions of the complexes resulted in the formation of dinuclear supramolecular compounds in which the anion is confined into the cavity that is formed by the two complexes. The supramolecular assembly process was monitored by UV/Vis absorption, luminescence, and NMR spectroscopy and high-resolution mass spectrometry. The X-ray crystal structure of the europium dimer revealed that the architecture of the scaffold is stabilized by synergistic effects of the Eu?F?Eu bridging motive, ??stacking interactions, and a four-component hydrogen-bonding network, which control the assembly of the two [EuL] entities around the fluoride ion. The strong association in water allowed for the luminescence sensing of fluoride down to a detection limit of 24?nM. PMID:24909695

Liu, Tao; Nonat, Aline; Beyler, Maryline; Regueiro-Figueroa, Martín; Nchimi Nono, Katia; Jeannin, Olivier; Camerel, Franck; Debaene, François; Cianférani-Sanglier, Sarah; Tripier, Raphaël; Platas-Iglesias, Carlos; Charbonnière, Loïc J

2014-07-01

350

Direct modulation of lanthanide emission at sub-lifetime scales.  

PubMed

The long lifetime of lanthanide emitters can present a challenge for conventional pump-based modulation schemes, where the maximum switching speed is limited by the decay time of the excited state. However, spontaneous emission can also be controlled through the local optical environment. Here, we demonstrate a direct modulation scheme enabled by dynamic control of the local density of optical states (LDOS). Specifically, we exploit the LDOS differences between electric and magnetic dipole transitions near a metal mirror and demonstrate that rapid nanometer-scale mirror displacements can modulate the emission spectra of trivalent europium ions within their excited state lifetime. The dynamic LDOS modulation presented here can be readily extended to faster optical modulation schemes and applied to other long-lived emitters to control the direction, polarization, and spectrum of spontaneous emission at sublifetime scales. PMID:23597062

Karaveli, Sinan; Weinstein, Aaron J; Zia, Rashid

2013-05-01

351

Energetic ionic liquids based on lanthanide nitrate complex anions.  

PubMed

Energetic ionic liquids based on anionic lanthanide nitrate complexes Cat(+) (3)[Ln(NO(3))(6)](3-), where Cat(+) is guanidinium, 4-aminotriazolium, 4-amino-1-methyltriazolium, 4-amino-1-ethyltriazolium, 4-amino-1-butyltriazolium, 1,5-diaminotetrazolium, and 1,5-diamino-4-methyltetrazolium, were prepared. The hexanitratolanthanate (-cerate) salts with the last two cations, which are the first CO-balanced energetic ionic liquids that are stable to hydrolysis and air, have impact sensitivities of about 27 J. These ionic liquids were obtained by an environmentally friendly, simple method using nitrate-containing precursors. All salts were fully characterized by IR and NMR spectroscopy, elemental analysis, and determination of thermal stability, phase behavior, density, and water content. According to theoretical calculations, these new compounds have potential as propellants. PMID:18973160

Tao, Guo-Hong; Huang, Yangen; Boatz, Jerry A; Shreeve, Jean'ne M

2008-01-01

352

Pulsed photothermal spectroscopy applied to lanthanide and actinide speciation  

SciTech Connect

Several key elements important for the application of laser-based photothermal spectroscopies to the study of the complexation chemistry of lanthanides and actinides in solution have been demonstrated. The sensitivity of f-f electronic transition energies and band intensities to subtle changes in complexation was illustrated through comparison of visible and near infra-red absorption spectra of well-characterized U(IV) dimers with alkoxide ligands. Significant improvements in spectroscopic band resolution and energy measurement precision for solution species were shown to be achievable through work in frozen glasses at 77 K using a very simple cryogenic apparatus. A pulsed-laser photothermal spectroscopy apparatus was constructed and shown to be sensitive to optical density changes of 10{sup {minus}5} in an aqueous Nd{sup 3+} solution. In addition, the capability of obtaining photothermal lensing spectra of dilute actinide solutions in frozen glasses at 77 K was demonstrated. 6 refs., 5 figs.

Berg, J.M.; Morris, D.E.; Clark, D.L.; Tait, C.D.; Woodruff, W.H. (Los Alamos National Lab., NM (USA)); Ven Der Sluys, W.G. (Montana Univ., Missoula, MT (USA). Dept. of Chemistry)

1991-01-01

353

Thermodynamic properties of lanthanide metals in liquid bismuth  

NASA Astrophysics Data System (ADS)

Thermodynamic quantities of La, Gd, Tb, and Dy in liquid bismuth were experimentally determined by electromotive force (EMF) measurement using a cell consisting of molten alkaline chloride and liquid bismuth. Excess Gibbs energy changes and activity coefficients were determined at varying concentrations and temperatures. Through their temperature dependence, corresponding enthalpy changes and entropy changes were determined. The excess enthalpy changes of La, Gd, Tb, and Dy in liquid bismuth in a temperature range from 850 to 1100 K were evaluated to be, -221.54±2.31, -202.25±1.80, -199.83±0.55, and -193.80±0.99 kJ/mol, respectively. The systematic variation of excess enthalpy change of lanthanides along the 4f-series was discussed. As a result, it was found that the excess enthalpy changes of La, Gd, Tb, Dy, and Er are likely to depend linearly on the 2/3 power of their metallic volume.

Yamana, Hajimu; Sheng, Jiawei; Souda, Naohiko; Moriyama, Hirotake

2001-04-01

354

Shifts that divide populations  

NASA Astrophysics Data System (ADS)

If fitness landscape is non-concave, And the shift is wide, Then there is a good chance That population would divide. How does a population of organisms in an ecosystem respond to shifts in the environment? Answers to this question are critical to our understanding of the ecosystem and thus ability to manage it toward more desirable outcomes. We have developed a model of adaptation, based on replicator dynamics, in which we derive a simple but insightful threshold condition that separates two important types of responses: 'cohesive transition' in which the whole population changes gradually together, and 'population-dividing transition' in which the population splits into two groups with one eventually dominating the other. The threshold depends on the magnitude of the shift and the shape of the fitness landscape. Division in populations can fundamentally alter the functioning of the system; knowing the condition that gives rise to such division is thus fundamentally important.

Muneepeerakul, R.; Qubbaj, M. R.; Aggarwal, R.; Anderies, J. M.; Janssen, M. A.

2013-12-01

355

Temporally and spectrally resolved imaging microscopy of lanthanide chelates.  

PubMed Central

The combination of temporal and spectral resolution in fluorescence microscopy based on long-lived luminescent labels offers a dramatic increase in contrast and probe selectivity due to the suppression of scattered light and short-lived autofluorescence. We describe various configurations of a fluorescence microscope integrating spectral and microsecond temporal resolution with conventional digital imaging based on CCD cameras. The high-power, broad spectral distribution and microsecond time resolution provided by microsecond xenon flashlamps offers increased luminosity with recently developed fluorophores with lifetimes in the submicrosecond to microsecond range. On the detection side, a gated microchannel plate intensifier provides the required time resolution and amplification of the signal. Spectral resolution is achieved with a dual grating stigmatic spectrograph and has been applied to the analysis of luminescent markers of cytochemical specimens in situ and of very small volume elements in microchambers. The additional introduction of polarization optics enables the determination of emission polarization; this parameter reflects molecular orientation and rotational mobility and, consequently, the nature of the microenvironment. The dual spectral and temporal resolution modes of acquisition complemented by a posteriori image analysis gated on the spatial, spectral, and temporal dimensions lead to a very flexible and versatile tool. We have used a newly developed lanthanide chelate, Eu-DTPA-cs124, to demonstrate these capabilities. Such compounds are good labels for time-resolved imaging microscopy and for the estimation of molecular proximity in the microscope by fluorescence (luminescence) resonance energy transfer and of molecular rotation via fluorescence depolarization. We describe the spectral distribution, polarization states, and excited-state lifetimes of the lanthanide chelate crystals imaged in the microscope.

Vereb, G; Jares-Erijman, E; Selvin, P R; Jovin, T M

1998-01-01

356

Spectral studies of novel lanthanide-containing polymers by near-infrared and FT-Raman spectroscopy  

NASA Astrophysics Data System (ADS)

The near-infrared absorption and FT-Raman spectra, taken with a near-infrared Nd:YAG source, were measured for two novel lanthanide ionomer systems. These ionomers are lanthanide exchanged copolymers based on two types of acid copolymer. One is organic and includes ethylene copolymers with acrylic or methacrylic acid; the other is inorganic and consists of carboxylated polysiloxane copolymers. The FT-Raman spectra of these systems differ greatly. Those based on organic copolymers exhibit strong lanthanide absorption frequency-dependent fluorescence, while those based on carboxylated polysiloxane do not. This difference is discussed in terms of the extent of lanthanide ion association in the ionomers.

Rajagopalan, Padmavathy; Wang, Yong Zhong; Tsagaropoulos, George; Risen, William M.

1997-03-01

357

Candidate Reagents for Dissolution of Hanford Site Tank Sludges-Scoping Studies with Simulants Using Single Reagents and Their Mixtures  

SciTech Connect

Chemical agents were investigated for their efficacies in dissolving metal compound phases known to be present in Hanford tank waste sludges. The phases included Fe(OH)3, Cr(OH)3, Al(OH)3, MnO2, and Na2U2O7. In conjunction with laboratory testing, a survey of the technical literature also was performed to identify candidate reagents. The tests were conducted in three campaigns. First, scoping tests investigated individual agents identified in the literature review along with other candidate agents. Based on the scoping test results, follow-up testing was performed to investigate the efficacies of mixed citric/oxalic acids (CITROX) and mixed nitric/oxalic acids (NITROX). Overall, oxalic acid is the most effective single reagent, dissolving all of the solid phases to some extent. However, for MnO2 and Na2U2O7, reprecipitation soon followed dissolution. The MnO2 also oxidized at least two of organic acids tested, oxalic acid and citric acid, as shown by the evolution of gas during the tests with these reagents. The CITROX and NITROX tests failed to show beneficial synergistic effects in dissolving sludge phases. Instead, the findings suggest that the sequential addition of individual pure reagents (e.g., first citric acid to dissolve MnO2 and Na2U2O7 and removal of the solution followed by oxalic acid to dissolve the Fe, Cr, and Al hydroxides) may be more effective than individual or blended reagents.

Sinkov, Serguei I.

2003-08-25

358

Trivalent lanthanide lacunary phosphomolybdate complexes: a structural and spectroscopic study across the series [Ln(PMo11O39)2]11-.  

PubMed

We report the syntheses and crystal structures of (NH4)11[Ln(III)(PMo11O39)2.xH2O (where Ln = every trivalent lanthanide cation except promethium) in which two lacunary [PMo11O39]7- anions sandwich an 8-coordinate Ln(III) cation to yield the complex anion, [LnIII(PMo11O39)2]11-. The 14 salts crystallise in two different space groups, C2/c or P1, but the LnIII containing anions are isostructural across the whole series, a very rare example of such a complete study. Solid state and solution 31P NMR, Raman and IR spectroscopies have been used to prove the stability of [Ln(PMo11O39)2]11- in aqueous solution. As expected, the LnIII cation contracts across the series and the Ln-O bond distances decrease uniformly. Interestingly, the splitting in the nu(P-O) mode within the [PMo11O39]7- unit increases uniformly across the series, which we attribute to the stronger interaction with the smaller, higher charge density LnIII cation as the series is traversed. For the 31P NMR measurements a direct comparison of Lanthanide Induced (paramagnetic) Shift could be made with the analogous [P(W11O39)2]11- complexes. PMID:15782262

Copping, Roy; Gaunt, Andrew J; May, Iain; Sarsfield, Mark J; Collison, David; Helliwell, Madeleine; Denniss, Iain S; Apperley, David C

2005-04-01

359

Lanthanides as NMR probes of fast molecular dynamics at high magnetic fields and temperature sensors: conformational interconversion of erbium ethylenediaminetetraacetate complexes.  

PubMed

(1)H NMR measurements are reported for D2O solutions of paramagnetic complex [Er(H2O)(EDTA(4-))](-) (I) for temperature interval 273-319 K. Diamagnetic complex [Lu(H2O)(EDTA(4-))](-) (II) was used as an NMR reference compound. The spectra obtained have been analyzed using a band-shape analysis technique in the framework of dynamic NMR (DNMR) taking into account the temperature dependence of lanthanide-induced shifts. Intramolecular dynamics in I was assigned to the interconversion of ?-?E-???? and ?-?E-???? conformers with estimated activation free energy ?G(‡)(298 K) = 50 ± 4 kJ/mol. The methodology of paramagnetic 4f-element probe applications on the example of Er(3+) for the study of free-energy changes in chemical exchange processes, as well as the advantages of this method in comparison with DNMR studies of diamagnetic substances, is discussed. In accordance with the literature reviewed, the fulfilled experimental study is the first example of intramolecular dynamics determination for erbium complexes. An additional advantage of the investigation is in the approach proposed which extends the range of measurement of the NMR rate constants for paramagnetic 4f-element complexes compared to diamagnetic ones. Coordination compounds investigated represent a new type of thermometric NMR sensors and lanthanide paramagnetic probes for in situ temperature control in solutions. PMID:23587055

Babailov, Sergey P; Stabnikov, Pavel A; Zapolotsky, Eugeny N; Kokovkin, Vasily V

2013-05-01

360

Trophic shift, not collapse  

USGS Publications Warehouse

scientists who are closely monitoring Lake Huron’s food web, we believe that the ongoing changes are more accurately characterized as a trophic shift in which benthic pathways have become more prominent. While decreases in abundance have occurred for some species, others are experiencing improved reproduction resulting in the restoration of several important native species.

Madenjian, Charles P.; Rutherford, Edward S.; Stow, Craig A.; Roseman, Edward F.; He, Ji X.

2013-01-01

361

Proton Chemical Shifts  

NSDL National Science Digital Library

Created by Hans Reich, professor of organic chemistry at the Uiversity of Wisconsin-Madison, this site contains a compilation of proton chemical shifts and coupling constants. This is an excellent resource for providing students familiarity with Nuclear Magnetic Resonance (NMR) Spectroscopy Data.

Reich, Hans J.

2007-11-16

362

Lanthanide(III) complexes with a tetrapyridine pendant-armed macrocyclic ligand: 1H NMR structural determination in solution, X-ray diffraction, and density-functional theory calculations.  

PubMed

Complexes between the tetrapyridyl pendant-armed macrocyclic ligand (L) and the trivalent lanthanide ions have been synthesized, and structural studies have been made both in the solid state and in aqueous solution. The crystal structures of the La, Ce, Pr, Gd, Tb, Er, and Tm complexes have been determined by single-crystal X-ray crystallography. In the solid state, all the cation complexes show a 10-coordinated geometry close to a distorted bicapped antiprism, with the pyridine pendants situated alternatively above and below the main plane of the macrocycle. The conformations of the two five-membered chelate rings present in the complexes change along the lanthanide series. The La(III) and Ce(III) complexes show a lambdadelta (or deltalambda) conformation, while the complexes of the heavier lanthanide ions present lambdalambda (or deltadelta) conformation. The cationic [Ln(L)]3+ complexes (Ln = La, Pr, Eu, Tb, and Tm) were also characterized by theoretical calculations at the density-functional theory (DFT) B3LYP level. The theoretical calculations predict a stabilization of the lambdalambda (or deltadelta) conformation on decreasing the ionic radius of the Ln(III) ion, in agreement with the experimental evidence. The solution structures show a good agreement with the calculated ones, as demonstrated by paramagnetic NMR measurements (lanthanide induced shifts and relaxation rate enhancements). The 1H NMR spectra indicate an effective D2 symmetry of the complexes in D2O solution. The 1H lanthanide induced shifts (LIS) observed for the Ce(III), Tm(III), and Yb(III) complexes can be fit to a theoretical model assuming that dipolar contributions are dominant for all protons. The resulting calculated values are consistent with highly rhombic magnetic susceptibility tensors with the magnetic axes being coincident with the symmetry axes of the molecule. In contrast with the solid-state structure, the analysis of the LIS data indicates that the Ce(III) complexes present a lambdalambda (or deltadelta) conformation in solution. PMID:16711699

Del C Fernandez-Fernandez, M; Bastida, R; Macías, A; Pérez-Lourido, P; Platas-Iglesias, C; Valencia, L

2006-05-29

363

Mechanisms of Hepatotoxicity Induced by Sulfhydryl Reagents (Mechanismen van Hepatotoxiciteit Geinduceerd door Sulfhydryl Reagentia).  

National Technical Information Service (NTIS)

In the thesis, the importance of sulfhydryl (SH) groups in hepatocyte function was studied by blocking these groups with various types of sulfhydryl reagents. The organic mercurials PCMB, PCMBS and mersalyl, the sulfhydryl-alkylating reagent NEM and disul...

J. H. Boot

1989-01-01

364

New chelating reagents for the separation of metal complexes by high performance liquid chromatography.  

National Technical Information Service (NTIS)

New chelating reagents for the complexation of metal ions in aqueous samples have been developed. The reagents synthesized and tested were 2,6-diacetylpyridine bis(N-methylenepyridiniohydrazone) dichloride (abbreviated H(sub 2)dapmp), 2,6-diacetylpyridine...

M. V. Main

1990-01-01

365

Controlled release of dry reagents in porous media for tunable temporal and spatial distribution upon rehydration.  

PubMed

Novel methods are demonstrated that enable controlled spatial and temporal rehydration of dried reagents in a porous matrix. These methods can be used in paper-based microfluidic assays to define reagent concentrations over time at zones downstream for improved performance, and can reduce costs by simplifying the manufacturing process with the use of a single porous substrate. First, the creation of uniform reagent pulses from patterned arrays of dried reagent is demonstrated. Second, reagents are stored dry in separate regions of the porous matrix so that they can be combined upon rehydration for immediate use in the device. Third, reagents are reconstituted sequentially from dry storage depots with tunable delivery times. Fourth, the total time for dissolution is varied to achieve a range of reagent delivery times to a downstream region. Finally, the utility of these control methods is demonstrated in the context of real-time reagent rehydration and mixing on a porous device. PMID:22960691

Fridley, Gina E; Le, Huy Q; Fu, Elain; Yager, Paul

2012-11-01

366

21 CFR 866.3410 - Proteus spp. (Weil-Felix) serological reagents.  

Code of Federal Regulations, 2010 CFR

...Serological Reagents § 866.3410 Proteus spp. (Weil-Felix) serological...reagents. (a) Identification. Proteus spp. (Weil-Felix) serological...derived from the bacterium Proteus vulgaris used in agglutination...

2009-04-01

367

21 CFR 866.3410 - Proteus spp. (Weil-Felix) serological reagents.  

Code of Federal Regulations, 2010 CFR

...Serological Reagents § 866.3410 Proteus spp. (Weil-Felix) serological...reagents. (a) Identification. Proteus spp. (Weil-Felix) serological...derived from the bacterium Proteus vulgaris used in agglutination...

2010-04-01

368

21 CFR 866.3830 - Treponema pallidum tre-ponemal test reagents.  

Code of Federal Regulations, 2013 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3830 Treponema pallidum tre-ponemal test reagents....

2013-04-01

369

21 CFR 866.3720 - Streptococcus spp. exo-enzyme reagents.  

Code of Federal Regulations, 2013 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3720 Streptococcus spp. exo-enzyme reagents. (a)...

2013-04-01

370

Degradation of carbon tetrachloride by modified Fenton's reagent.  

PubMed

The degradation of tetrachloromethane (carbon tetrachloride-CT) by modified Fenton's reagent (catalyzed hydrogen peroxide) was investigated using a range of hydrogen peroxide concentrations and 1 mM iron(III) catalyst. The documented reactive species in modified Fenton's reactions, hydroxyl radical (OH*), is not reactive with CT, yet CT degradation was observed in the Fenton's reactions and was confirmed by chloride generation. Because CT is not reactive with OH*, a reductive mechanism which may involve superoxide radical anion is proposed for CT degradation in modified Fenton's systems. Scavenging of reductants by excess chloroform prevented CT degradation, confirming a reductive mechanism. Similar to CT, three other oxidized aliphatic compounds, hexachloroethane, bromotrichloromethane, and tetranitromethane, were also degraded by modified Fenton's reagent. The results show that modified Fenton's reactions act through a reductive mechanism to degrade compounds that are not reactive with OH*, which broadens the scope of this process for hazardous waste treatment and remediation. PMID:12169420

Teel, Amy L; Watts, Richard J

2002-10-01

371

Rapid transdermal bloodless and reagent-free malaria detection  

NASA Astrophysics Data System (ADS)

Successful diagnosis, screening, and elimination of malaria critically depend on rapid and sensitive detection of this dangerous infection, preferably transdermally and without sophisticated reagents or blood drawing. Such diagnostic methods are not currently available. Here we show that the high optical absorbance and nanosize of endogenous heme nanoparticles called hemozoin, a unique component of all blood-stage malaria parasites, generate a transient vapor nanobubble around hemozoin in response to a short and safe near-infrared picosecond laser pulse. The acoustic signals of these malaria-specific nanobubbles provided the first transdermal non-invasive and rapid detection of a malaria infection as low as 0.00034% in animals without using any reagents or drawing blood. These on-demand transient events have no analogs among current malaria markers and probes, can detect and screen malaria in seconds and can be realized as a compact, easy to use, inexpensive and safe field technology.

Lukianova-Hleb, Ekaterina Y.; Campbell, Kelly M.; Constantinou, Pamela E.; Braam, Janet; Olson, John S.; Ware, Russell E.; Sullivan, David S.; Lapotko, Dmitri

2014-02-01

372

Chemical oxidation of BTX using Fenton`s reagent  

SciTech Connect

Fenton`s reagent has proven to be an economically feasible and effective oxidant to destruct an extensive variety of hazardous wastes. In this work, benzene, toluene and xylene (BTX) were selected as model compounds subjected to oxidation using Fenton`s regent under batch conditions. Various factors deemed critical in optimizing the oxidation of organics were studied. Test results indicated that BTX can be effectively oxidized in aqueous solutions with Fenton`s reagent. At a H{sub 2}O{sub 2}: BTX: Fe{sup +2} ratio of 12; 1: 60 (mg/L), the dissolved BTX can be completely removed in a period less than ten minutes. A rate equation was derived for predicting the residual concentration of BTX in terms of the contact time. 19 refs., 8 figs.

Lou, J.C.; Lee, S.S. [National Sun Yat-Sen Univ., Kaohsiung (Taiwan, Province of China)

1995-12-31

373

Preparation and purification of zinc sulfinate reagents for drug discovery.  

PubMed

The present protocol details the synthesis of zinc bis(alkanesulfinate)s that can be used as general reagents for the formation of radical species. The zinc sulfinates described herein are generated from the corresponding sulfonyl chlorides by treatment with zinc dust. The products may be used crude, or a simple purification procedure may be performed to minimize incorporation of water and zinc chloride. Although the synthesis of the zinc sulfinate salts can generally be completed within 3 h, workup can take up to 24 h and purification can take up to 3 h. Following the steps in this protocol would enable the user to generate a small toolkit of zinc sulfinate reagents over the course of 1 week. PMID:23640168

O'Hara, Fionn; Baxter, Ryan D; O'Brien, Alexander G; Collins, Michael R; Dixon, Janice A; Fujiwara, Yuta; Ishihara, Yoshihiro; Baran, Phil S

2013-06-01

374

Release of organic reagents from solidified decontamination wastes  

SciTech Connect

In order to provide technical information needed by the US Nuclear Regulatory Commission to evaluate the adequacy of near-surface disposal of decontamination wastes, Brookhaven National Laboratory has measured the release of organic reagents from solidified simulated decontamination wastes. The waste streams consisted of either mixed-bed ion-exchange resins or anion exchange resins equilibrated with EDTA, oxalic acid, citric acid, picolinic acid or simulated LOMI decontamination reagent. These simulated resin wastes were solidified in either cement or vinyl ester-styrene. Samples were tested by a fixed interval leach procedure or according to the standard ANS 16.1 procedure. The leachability indices, which were calculated as prescribed in ANS 16.1, varied with leach period for some of the composites tested. 4 references, 6 figures, 2 tables.

Piciulo, P.L.; Adams, J.W.

1985-01-01

375

Lanthanides inhibit adipogenesis with promotion of cell proliferation in 3T3-L1 preadipocytes.  

PubMed

Lanthanides are widely used in various fields for industrial, agricultural and medical purposes. They have also been used in Chinese agriculture either as fertilizers in plant production or as performance-enhancers in animal nutrition for many years. In view of their possible application for growth enhancing purposes and new medical applications, detailed information on how lanthanides influence physiological processes in biological systems is indispensable. In the present work, the effects of lanthanides (LaCl3, CeCl3 and GdCl3) on cell proliferation and adipogenesis in 3T3-L1 preadipocytes were evaluated. The results demonstrate that lanthanides inhibit adipogenesis in 3T3-L1 preadipocytes, evidenced by decreased triglyceride content and expression of C/EBP? and PPAR?. Simultaneously, the results show that lanthanides can promote cell proliferation during the different stages of differentiation. Firstly, prior to the addition of differentiation inducers (MDI), all the three types of lanthanides resulted in a significant increase of cell growth. Secondly, during the mitotic clonal expansion (MCE) process, GdCl3, as a representative compound, is able to promote cell-cycle entry into the S phase and levels of cell cycle-regulating proteins. Third, at the late stage of the terminal differentiation, on day 8, in the presence of GdCl3, cells exhibited higher levels of G1/S regulatory proteins and proliferating cell nuclear antigen (PCNA). In addition, GdCl3 caused stronger sustained ERK activation during the differentiation process of 3T3-L1 cells. The present study demonstrates that lanthanides may modulate lipid metabolism by inhibition of adipocyte differentiation. The sustained activation of the ERK pathway might be responsible for their inhibition of differentiation and a possible link between their pro-proliferative ability and inhibition of the differentiation process is indicated. PMID:23612852

Hou, Cong-Cong; Feng, Min; Wang, Kui; Yang, Xiao-Gai

2013-06-01

376

Dielectric Properties Investigation of Polyaniline Prepared by Using Fenton's Reagent  

Microsoft Academic Search

The frequency dependence of the dielectric properties and dc conductivity (?dc) of polyaniline samples that have been prepared in a conducting state by a chemical method using Fenton's reagent were investigated. These samples were prepared at constant molar ratio H2O2\\/aniline (r = 1) and at different concentrations of both H2O2 and aniline (0.2 M, 0.4 M, and 0.5 M). The measurements were carried out using

M. M. Ayad; M. K. El-Nimr; E. A. Zaki

2009-01-01

377

Functionalization of heterocyclic compounds using polyfunctional magnesium and zinc reagents  

PubMed Central

Summary In this review we summarize the most important procedures for the preparation of functionalized organzinc and organomagnesium reagents. In addition, new methods for the preparation of polyfunctional aryl- and heteroaryl zinc- and magnesium compounds, as well as new Pd-catalyzed cross-coupling reactions, are reported herein. Experimental details are given for the most important reactions in the Supporting Information File 1 of this article.

Schade, Matthias A; Bernhardt, Sebastian; Manolikakes, Georg; Metzger, Albrecht; Piller, Fabian M; Rohbogner, Christoph J; Mosrin, Marc

2011-01-01

378

Oxidation kinetics and mechanisms of trihalomethanes by Fenton's reagent  

Microsoft Academic Search

Oxidation kinetics and mechanisms of four trihalomethanes (THMs) commonly found in chlorinated drinking water by Fenton's reagent were investigated. All the experiments were carried out in air-tight and well-mixed batch reactors in which no headspace was allowed in order to minimize volatilization of any THM during reaction. The optimum dosages of H2O2 and Fe2+ in the oxidation of bromoform was

Walter Z. Tang; Stephanie Tassos

1997-01-01

379

Controlled Reagent Transport in Disposable 2D Paper Networks  

PubMed Central

Recent reports have demonstrated the multi-analyte detection capability of paper networks with multiple outlets per inlet. In this report, we focus on the capabilities of 2D paper networks with multiple inlets per outlet and demonstrate the controlled transport of reagents within paper devices. Specifically, we demonstrate methods of controlling fluid transport using the geometry of the network and dissovable barriers. Finally, we discuss the implications for higher sensitivity detection using this type of 2D paper network.

Fu, Elain; Lutz, Barry; Kauffman, Peter; Yager, Paul

2011-01-01

380

Production of hydroxyl radicals by electrochemically assisted Fenton's reagent  

Microsoft Academic Search

Hydroxyl radicals are very powerful oxidizing agents. They are involved in hydroxylation reactions, in biological and atmospheric phenomena. A recent application of these radicals is their use in decontamination of water polluted by toxic organic substances like pesticides. Chemically, these radicals are produced by the use of a mixture of (H2O2+Fe2+), the so called Fenton's reagent. In this work Fenton's

Mehmet A. Oturan; Nihal Oturan; Claude Lahitte; Stéphane Trevin

2001-01-01

381

Aminodifluorosulfinium tetrafluoroborate salts as stable and crystalline deoxofluorinating reagents.  

PubMed

Aminodifluorosulfinium tetrafluoroborate salts were found to act as efficient deoxofluorinating reagents when promoted by an exogenous fluoride source and, in most cases, exhibited greater selectivity by providing less elimination byproduct as compared to DAST and Deoxo-Fluor. Aminodifluorosulfinium tetrafluoroborates are easy handled crystalline salts that show enhanced thermal stability over dialkylaminosulfur trifluorides, are storage-stable, and unlike DAST and Deoxo-Fluor do not react violently with water. PMID:19799406

Beaulieu, Francis; Beauregard, Louis-Philippe; Courchesne, Gabriel; Couturier, Michel; LaFlamme, François; L'Heureux, Alexandre

2009-11-01

382

A new reagent method for descaling heat-exchanging equipment  

Microsoft Academic Search

Corrosion and electrochemical studies of metallic materials (steel, St2, 08Kh22N6T, 12KhI8NIOT, copper M3, brass L062~I, aluminum ADI, titanium VT-O) applicable fo~ fabrication of heat-exchanging equipment were made to explore the scope of industrial use of the new reagent method. The tests were carried out on a special setup (Fig. i). The extent of carbonate scale removal and the corrosion rate

L. A. Luchinina; T. D. Konovalova; F. K. Davlet'yarova

1986-01-01

383

Dehalogenation of Monohalopyridines Catalyzed by Group 4 Metallocene Reagent  

Microsoft Academic Search

The Cp'2MCl2\\/hydride (Cp' = Cp or Cp*: Cp = ?5-C5H5, Cp* = ?5-C5Me5; M = Ti, Zr, Hf) reagent catalyzes the dehalogenation of monohalopyridines at room temperature to give pyridine. The catalytic activity decreases in the order of M = Ti > Zr > Hf: M-F ? M-Cl ? M-Br ? M-I; Cp2M > CpCp* M>C p *2M; Red-Al >

Bo-Hye Kim; Hee-Gweon Woo; Whan-Gi Kim; Sock-Sung Yun; Taek-Sung Hwang

384

Reagent Selection Methodology for a Novel Explosives Detection Platform  

ScienceCinema

This video describes research being conducted by Dr. Marvin Warner, a research scientist at Pacific Northwest National Laboratory, in the individual pieces of antibodies used to set up a chemical reaction that will give off light just by mixing reagents together with a sample that contains an explosive molecule. This technology would help detect if explosives are present with just the use of a handheld system or container.

None

2012-12-31

385

Asymmetric Conjugate Addition of Alkylzirconium Reagents to ?,?-Unsaturated Lactones.  

PubMed

The asymmetric synthesis of ?-substituted lactones by catalytic asymmetric conjugate addition of alkyl groups to ?,?-unsaturated lactones is reported. The method uses alkylzirconium nucleophiles prepared in situ from alkenes and the Schwartz reagent. Enantioselective additions to 6- and 7-membered lactones proceed at rt, tolerate a wide variety of functional groups, and are readily scalable. The method was used in a formal asymmetric synthesis of mitsugashiwalactone. PMID:24893570

Maciver, Eleanor E; Maksymowicz, Rebecca M; Wilkinson, Nancy; Roth, Philippe M C; Fletcher, Stephen P

2014-06-20

386

Reagent Selection Methodology for a Novel Explosives Detection Platform  

SciTech Connect

This video describes research being conducted by Dr. Marvin Warner, a research scientist at Pacific Northwest National Laboratory, in the individual pieces of antibodies used to set up a chemical reaction that will give off light just by mixing reagents together with a sample that contains an explosive molecule. This technology would help detect if explosives are present with just the use of a handheld system or container.

None

2010-06-01

387

Chromatography-free Wittig reactions using a bifunctional polymeric reagent.  

PubMed

The first example of a polystyrene bearing two distinct reagent groups has been prepared. This phosphine and amine functionalized material was used in one-pot Wittig reactions with an aldehyde and either an ?-halo-ester, -ketone, or -amide. Due to the heterogeneous nature of the polymer, the desired alkene product of these reactions could be isolated in excellent yield in essentially pure form after only filtration and solvent removal. PMID:20936814

Leung, Peter Shu-Wai; Teng, Yan; Toy, Patrick H

2010-11-01

388

Partial inactivation of cytochrome c oxidase by nonpolar mercurial reagents  

Microsoft Academic Search

Purified beef heart cytochrome c oxidase is inactivated to the extent of 35 to 50% by the nonpolar mercurial reagents mercuric chloride and ethylmercuric chloride. The inactivation is complete within 5 min. In titrations of activity, the plateau level of inactivation is attained at added ethylmercuric chloride:heme a ratios of about 1:1. Up to 3 mercury atoms\\/heme a are bound

A. J. Mann; H. E. Auer

1980-01-01

389

Unusual reactions of Grignard reagents toward fluoroalkylated esters  

Microsoft Academic Search

Fluorine-containing esters were demonstrated to be convenient substrates for construction of the corresponding ketones by low temperature reaction with Grignard reagents followed by warming up to 0°C, while heating the mixture up to 80°C readily promoted the reduction of the ketones obtained by the generated magnesium alkoxides whose mechanism was speculated as Meerwein–Ponndorf–Verley type reduction by computational technique.

Takashi Yamazaki; Tsukasa Terajima; Tomoko Kawasaki-Taskasuka

2008-01-01

390

Synthesis and olefination of carbonyl compounds using solid-supported reagents.  

PubMed

The development and application of three new solid-supported reagents for use in the synthesis or olefination of carbonyl compounds are described. The reagents include the Weinreb amide, Mukaiyama's S-2-pyridyl thioate and a Peterson methylenation reagent. As solid-supports p-benzyl alcohol resin, Wang resin and Merrifield resin (1-2% crosslinked polystyrene) have been used. PMID:17268646

Hansen, Anne-Lene L; Murray, Anthony; Tanner, David

2006-12-21

391

Generation of radicals in Grignard reagent formation in the framework of the cluster model  

Microsoft Academic Search

The Grignard reagent RMgHaL (R is radical, Hal is halogen) is one of the most widely used reagents in synthetic organic chemistry. This reagent is commonly synthesized by the reaction of magnesium with organic halide, mostly bromide, in ether: RBr + Mg z + 2(C 2 H 5 ) 2 O RMgBr · 2(C 2 H 5 ) 2 O

V. V. Porsev; A. V. Tulub

2008-01-01

392

UV Decontamination of MDA Reagents for Single Cell Genomics  

SciTech Connect

Single cell genomics, the amplification and sequencing of genomes from single cells, can provide a glimpse into the genetic make-up and thus life style of the vast majority of uncultured microbial cells, making it an immensely powerful and increasingly popular tool. This is accomplished by use of multiple displacement amplification (MDA), which can generate billions of copies of a single bacterial genome producing microgram-range DNA required for shotgun sequencing. Here, we address a key challenge inherent to this approach and propose a solution for the improved recovery of single cell genomes. While DNA-free reagents for the amplification of a single cell genome are a prerequisite for successful single cell sequencing and analysis, DNA contamination has been detected in various reagents, which poses a considerable challenge. Our study demonstrates the effect of UV irradiation in efficient elimination of exogenous contaminant DNA found in MDA reagents, while maintaining Phi29 activity. Consequently, we also find that increased UV exposure to Phi29 does not adversely affect genome coverage of MDA amplified single cells. While additional challenges in single cell genomics remain to be resolved, the proposed methodology is relatively quick and simple and we believe that its application will be of high value for future single cell sequencing projects.

Lee, Janey; Tighe, Damon; Sczyrba, Alexander; Malmatrom, Rex; Clingenpeel, Scott; Malfatti, Stephanie; Rinke, Christian; Wang, Zhong; Stepanauskas, Ramunas; Cheng, Jan-Fang; Woyke, Tanja

2011-03-18

393

Aptamers and the next generation of diagnostic reagents.  

PubMed

Antibodies have been extensively used as capture and detection reagents in diagnostic applications of proteomics-based technologies. Proteomic assays need high sensitivity and specificity, a wide dynamic range for detection, and accurate, reproducible quantification with small confidence values. However, several inherent limitations of monoclonal antibodies in meeting the emerging challenges of proteomics led to the development of a new class of oligonucleotide-based reagents. Natural and derivatized nucleic acid aptamers are emerging as promising alternatives to monoclonal antibodies. Aptamers can be effectively used to simultaneously detect thousands of proteins in multiplex discovery platforms, where antibodies often fail due to cross-reactivity problems. Through chemical modification, vast range of additional functional groups can be added at any desired position in the oligonucleotide sequence, therefore the best features of small molecule drugs, proteins, and antibodies can be brought together into aptamers, making aptamers the most versatile reagent in proteomics. In this review, we discuss the recent developments in aptamer technology, including new selection methods and the aptamers' application in proteomics. PMID:23090891

Thiviyanathan, Varatharasa; Gorenstein, David G

2012-12-01

394

A new reagent (ZZAP) having multiple applications in immunohematology.  

PubMed

A reagent (ZZAP) containing a mixture of 0.1 M dithiothreitol (DTT) plus 0.1% cysteine-activated papain was found to dissociate IgG immunoglobulin from red blood cells (RBC) of patients having a positive direct antiglobulin test (DAT) although this could not be achieved with either chemical alone. In all 67 patients tested, ZZAP treatment of IgG sensitized RBC reduced the strength of the DAT, and in all 52 instances tested, this allowed for accurate Rh phenotyping using slide/rapid tube typing reagents. This included five examples in which spontaneous agglutination that occurred in saline or 6% albumin was eliminated by ZZAP. Thus, all red blood cell typing for Rh-Hr antigens was accomplished using slide/rapid tube reagents making unnecessary the use of saline reactive or chemically modified antisera. Kidd antigen typing is also possible after ZZAP treatment of IgG sensitized RBC. In regard to warm autoabsorption tests, ZZAP treatment of 14 RC samples having a positive DAT proved preferable to heat elution technics since equal or greater amounts of IgG were removed by ZZAP and little or no hemolysis resulted. ZZAP has no effect on ABH, Rh or Kidd antigens but denatures Duffy, MNSs and all Kell antigens tested (K:1-K:7, K:11-K:14, K:18, K:19). This should prove valuable in certain investigations of multiple alloantibodies and, moreover, may allow for better characterization of Kell antigens. PMID:6808844

Branch, D R; Petz, L D

1982-08-01

395

Aptamers and the Next Generation of Diagnostic Reagents  

PubMed Central

Antibodies have been extensively used as capture and detection reagents in diagnostic applications of proteomics-based technologies. Proteomic assays need high sensitivity and specificity, a wide dynamic range for detection, and accurate, reproducible quantification with small confidence values. However, several inherent limitations of monoclonal antibodies in meeting the emerging challenges of proteomics led to the development of a new class of oligonucleotide-based reagents. Natural and derivatized nucleic acid aptamers are emerging as promising alternatives to monoclonal antibodies. Aptamers can be effectively used to simultaneously detect thousands of proteins in multiplex discovery platforms, where antibodies often fail due to cross-reactivity problems. Through chemical modification, vast range of additional functional groups can be added at any desired position in the oligonucleotide sequence, therefore the best features of small molecule drugs, proteins and antibodies can be brought together into aptamers, making aptamers the most versatile reagent in proteomics. In this review we discuss the recent developments in aptamer technology, including new selection methods and the aptamers’ application in proteomics.

Thiviyanathan, Varatharasa; Gorenstein, David G.

2014-01-01

396

Solid-water detoxifying reagents for chemical and biological agents  

DOEpatents

Formation of solid-water detoxifying reagents for chemical and biological agents. Solutions of detoxifying reagent for chemical and biological agents are coated using small quantities of hydrophobic nanoparticles by vigorous agitation or by aerosolization of the solution in the presence of the hydrophobic nanoparticles to form a solid powder. For example, when hydrophobic fumed silica particles are shaken in the presence of IN oxone solution in approximately a 95:5-weight ratio, a dry powder results. The hydrophobic silica forms a porous coating of insoluble fine particles around the solution. Since the chemical or biological agent tends to be hydrophobic on contact with the weakly encapsulated detoxifying solution, the porous coating breaks down and the detoxifying reagent is delivered directly to the chemical or biological agent for maximum concentration at the point of need. The solid-water (coated) detoxifying solutions can be blown into contaminated ventilation ducting or other difficult to reach sites for detoxification of pools of chemical or biological agent. Once the agent has been detoxified, it can be removed by flushing the area with air or other techniques.

Hoffman, Dennis M. (Livermore, CA); Chiu, Ing Lap (Castro Valley, CA)

2006-04-18

397

Nursing rotas. Shift up.  

PubMed

Trusts may wish to consider more flexible, staggered daytime shifts, which accommodate married nurses--for instance, 9.30 am-3.30 pm on weekdays with longer hours at weekends/on nights to ensure that contractual requirements are met. For larger trusts, creche/nursery facilities may solve the problem. After-school clubs on site on a voluntary basis may also mean that more married women and unmarried women with children could more easily accommodate standard shifts. The tribunal decision seems to condone the provision of somewhat ad hoc training and supervision, whereas in professional practice continuous supervision and participation in professional developments are essential elements in the provision of safe, high-quality clinical practice. PMID:10623151

Lloyd, R; Goulding, J

1999-10-14

398

Ambiguous red shifts  

NASA Astrophysics Data System (ADS)

A one-parameter conformal invariance of Maxwell's equations allows the wavelengths of electromagnetic waves to change as they propagate, and do so even in otherwise field-free space. This produces an ambiguity in interpretations of stellar red shifts. Experiments that will determine the value of the group parameter, and thereby remove the ambiguity, are proposed. They are based on an analysis of the anomalous frequency shifts uncovered in the Pioneer 10 and 11 spacecraft studies, and physical interpretation of an isomorphism discovered by E.L. Hill. If the group parameter is found to be non-zero, Hubble's relations will have to be reinterpreted and space-time metrics will have to be altered. The cosmological consequences of the transformations are even more extensive because, though they change frequencies they do not alter the energy and momentum conservation laws of classical and quantum-electrodynamical fields established by Cunningham and by Bia?ynicki-Birula.

Wulfman, Carl E.

2010-12-01

399

X-ray excited-optical luminescence of lanthanides in phosphors prepared from yttrium oxide and iron transition-group oxides: application to the determination of lanthanides in iron and its alloys  

Microsoft Academic Search

A series of new phosphors was prepared using yttrium oxide and the ; oxides of the iron transition group elements. These phosphors when excited by x-; ray radiation are strongly luminescent in the visible spectral region if the ; oxides of the iron-group oxides contain lanthanide elements. These phosphors ; were used for the determination of several lanthanides at the

Edward L. DeKalb; Velmer A. Fassel

1975-01-01

400

Effect of lanthanide contraction on the mixed polyamine systems Ln/Sb/Se/(en+dien) and Ln/Sb/Se/(en+trien): Syntheses and characterizations of lanthanide complexes with a tetraelenidoantimonate ligand  

NASA Astrophysics Data System (ADS)

Mixed polyamine systems Ln/Sb/Se/(en+dien) and Ln/Sb/Se/(en+trien) (Ln=lanthanide, en=ethylenediamine, dien=diethylenetriamine, trien=triethylenetetramine) were investigated under solvothermal conditions, and novel mixed-coordinated lanthanide(III) complexes [Ln(en) 2(dien)( ?2-SbSe 4)] ( Ln=Ce( 1a), Nd( 1b)), [Ln(en) 2(dien)(SbSe 4)] ( Ln=Sm( 2a), Gd( 2b), Dy( 2c)), [Ln(en)(trien)( ?- ?1, ?2-SbSe 4)] ? ( Ln=Ce( 3a), Nd( 3b)) and [Sm(en)(trien)( ?2-SbSe 4)] ( 4a) were prepared. Two structural types of lanthanide selenidoantimonates were obtained across the lanthanide series in both en+dien and en+trien systems. The tetrahedral anion [SbSe 4] 3- acts as a monodentate ligand mono-SbSe 4, a bidentate chelating ligand ?2-SbSe 4 or a tridentate bridging ligand ?- ?1, ?2-SbSe 4 to the lanthanide(III) center depending on the Ln 3+ ions and the mixed ethylene polyamines, indicating the effect of lanthanide contraction on the structures of the lanthanide(III) selenidoantimonates. The lanthanide selenidoantimonates exhibit semiconducting properties with Eg between 2.08 and 2.51 eV.

Zhao, Jing; Liang, Jingjing; Pan, Yingli; Zhang, Yong; Jia, Dingxian

2011-06-01

401

A review of reagents for fluorescence microscopy of cellular compartments and structures, part I: BacMam labeling and reagents for vesicular structures.  

PubMed

Fluorescent labeling of vesicular structures in cultured cells, particularly for live cells, can be challenging for a number of reasons. The first challenge is to identify a reagent that will be specific enough where some structures have a number of potential reagents and others very few options. The emergence of BacMam constructs has allowed more easy-to-use choices. Presented here is a discussion of BacMam constructs as well as a review of commercially-available reagents for labeling vesicular structures in cells, including endosomes, peroxisomes, lysosomes, and autophagosomes, complete with a featured reagent for each structure, recommended protocol, troubleshooting guide, and example image. PMID:23835803

Dolman, Nick J; Kilgore, Jason A; Davidson, Michael W

2013-07-01

402

The shifting beverage landscape.  

PubMed

STOREY, M.L. The shifting beverage landscape. PHYSIOL BEHAV, 2010. - Simultaneous lifestyle changes have occurred in the last few decades, creating an imbalance in energy intake and energy expenditure that has led to overweight and obesity. Trends in the food supply show that total daily calories available per capita increased 28% since 1970. Total energy intake among men and women has also increased dramatically since that time. Some have suggested that intake of beverages has had a disproportional impact on obesity. Data collected by the Beverage Marketing Corporation between 1988-2008 demonstrate that, in reality, fewer calories per ounce are being produced by the beverage industry. Moreover, data from the National Cancer Institute show that soft drink intake represents 5.5% of daily calories. Data from NHANES 1999-2003 vs. 2003-06 may demonstrate a shift in beverage consumption for age/gender groups, ages 6 to>60years. The beverages provided in schools have significantly changed since 2006 when the beverage industry implemented School Beverage Guidelines. This voluntary action has removed full-calorie soft drinks from participating schools across the country. This shift to lower-calorie and smaller-portion beverages in school has led to a significant decrease in total beverage calories in schools. These data support the concept that to prevent and treat obesity, public health efforts should focus on energy balance and that a narrow focus on sweetened beverages is unlikely to have any meaningful impact on this complex problem. PMID:20188750

Storey, Maureen

2010-04-26

403

Coupling of the 4f Electrons in Lanthanide Molecules  

SciTech Connect

(C5Me5)2LnOTf where Ln = La, Ce, Sm, Gd, and Yb have been synthesized and these derivatives are good starting materials for the synthesis of (C5Me5)2LnX derivatives. (C5Me5)2Ln(2,2'-bipyridine), where Ln = La, Ce, Sm, and Gd, along with several methylated bipyridine analogues have been synthesized and their magnetic moments have been measured as a function of temperature. In lanthanum, cerium, and gadolinium complexes the bipyridine ligand ligand is unequivocally the radical anion, and the observed magnetic moment is the result of intramolecular coupling of the unpaired electron on the lanthanide fragment with the unpaired electron on the bipyridine along with the intermolecular coupling between radicals. Comparison with the magnetic moments of the known compounds (C5Me5)2Sm(2,2'-bipyridine) and (C5Me5)2Yb(2,2'-bipyridine) leads to an understanding of the role of the Sm(II)/Sm(III) and Yb(II)/Yb(III) couple in the magnetic properties of (C5Me5)2Sm(2,2'-bipyridine) and (C5Me5)2Yb(2,2'-bipyridine). In addition, crystal structures of (C5Me5)2Ln(2,2'-bipyridine) and [(C5Me5)2Ln(2,2'-bipyridine)][BPh4](Ln= Ce and Gd), where the lanthanide is unequivocally in the +3 oxidation state, give the crystallographic characteristics of bipyridine as an anion and as a neutral ligand in the same coordination environment, respectively. Substituted bipyridine ligands coordinated to (C5Me5)2Yb are studied to further understand how the magnetic coupling in (C5Me5)2Yb(2,2'-bipyridine) changes with substitutions. In the cases of (C5Me5)2Yb(5,5'-dimethyl-2,2'-bipyridine) and (C5Me5)2Yb(6-methyl-2,2'-bipyridine), the valence, as measured by XANES, changes as a function of temperature. In general, the magnetism in complexes of the type (C5Me5)2Yb(bipy.-), where bipyo represents 2,2'-bipyridine and substituted 2,2'-bipyridine ligands, is described by a multiconfiguration model, in which the ground state is an open-shell singlet composed of two configurations: Yb(III, f13)(bipy.-) and Yb(II, f14)(bipyo). The relative contributions of the two configurations depends on the substituents on the bipyridine ligand.[(C5H4Me)3Ln]2(L) (Ln = Ce, Tb; L = 4,4'-bipyridine, 1,4-benzoquinone) are synthesized in order to study the effect of these ligands on the oxidation states of the metal as well as to study intramolecular coupling between two lanthanides fragments.

Kazhdan, Daniel

2008-09-12

404

An analysis of the performance of membrane reactors for the water–gas shift reaction using gas feed mixtures  

Microsoft Academic Search

The water–gas shift (WGS) reaction in membrane reactors has been widely studied by several authors. From these works, the increase of the CO conversion above the equilibrium values appears to be possible when hydrogen is removed through the membrane.However, to date, this feasibility has been verified mostly when feeding pure reagents to the reactor, although in an industrial context the

A Criscuoli; A Basile; E Drioli

2000-01-01

405

Evaluation of shift agents for potential application to Na and H-1 NMR imaging  

SciTech Connect

The development and use of paramagnetic NMR contrast agents for NMR imaging application has been actively pursued in recent years. The two major types of agents investigated have been the metal ion chelates (e.g. Gd-DTPA) and the organic free radicals such as the nitroxides. Both of these types of agents fall in the class of contrast agents which effect the T/sub 1/ of nuclei such as H-1. The relaxation contrast agents can cause 50-100% enhancement of the H-1 signal in NMR imaging. A potential advantage of shift agents versus relaxation agents in NMR imaging applications is the very high contrast achievable using shift agents. In this work the spectroscopic evaluation of EDTA, DTPA and TTHA chelates of Thulium (Tm) and Dysprosium (Dy) was undertaken to determine their potential as sodium and proton NMR shift agents. The Dy chelates were found to induce downfield shifts in the Na-23 and H-1 NMR signals while the Tm analogs caused either downfield or upfield shifts depending upon the ligand used. In all cases the Dy complexes induced greater shifts than Tm as expected form the larger magnetic moment of Dy/sup +3/ versus Tm/sup +3/. The magnitude of shift for Na-23 was generally greater than for H-1 an the degree of Na-23 shift showed a pH dependency in the pH range of 2-7 of the metal complex solution. These effects are consistent with an enhanced NMR shift caused by electrostatic interactions of the positively charged Na-23 and negatively charged lanthanide complexes. The application of shift agents to contrast enhancement in H-1 NMR imaging of a phantom is demonstrated.

Carpenter, A.P. Jr.; Wolshin, E.M.; Srinivasan, P.R.; Fossel, E.T.

1985-05-01

406

Frequency-domain measurement of luminescent lanthanide chelates.  

PubMed

The sinusoidal modulation of excitation intensity and phase-sensitive detection of emission is ideally suitable for the accurate determination of the lifetime and intensity of lanthanide luminescence. In this work we elaborate on the general mathematical and instrumental techniques of the frequency-domain (FD) measurements in the low-frequency domain below 100 kHz. A modular FD luminometer is constructed by using a UV-LED as the excitation source, proper light filters in the excitation and emission paths, a photomultiplier with a fast preamplifier, and a conventional dual-phase lock-in amplifier. Starting from the set of linear differential equations governing the excited-state processes of the lanthanide chelates, an equation linking the luminescence intensity to the general form of the excitation modulation was derived. Application to the sinusoidal modulation in the Euler's exponential form gives the expression for the in-phase and out-of-phase signals of a dual-phase lock-in amplifier. It is shown that by using a relatively large number of logarithmically equidistant modulation frequencies it is possible to use the Kramers-Kronig relation for checking the compatibility of the out-of-phase and in-phase signals. As an example, the emission from two different europium(III) chelates were measured by using 200 modulation frequencies between 10 Hz and 100 kHz. In addition to the conventional transition between (5)D(0) and (7)F(2) levels emitting at 615 nm, also the emission from the transition between (5)D(1) and (7)F(1) levels at ca. 540 nm was measured. The latter emission was also measured at different temperatures, yielding the energy difference between the (5)D(1) and (5)D(0) levels. The relatively large number of modulation frequencies allows also an accurate determination of lifetimes and corresponding amplitudes by using an appropriate nonlinear regression method. Comparison of the time-domain and frequency-domain methods shows that the weighting of data is different and both methods have application areas of their own. PMID:20617797

Hyppänen, Iko; Soukka, Tero; Kankare, Jouko

2010-08-01

407

Synthesis and structural characterization of nonanuclear lanthanide complexes.  

PubMed

A series of nonanuclear lanthanide oxo-hydroxo complexes of the general formula [Ln(9)(mu(4)-O)(2)(mu(3)-OH)(8)(mu-BA)(8)(BA)(8)](-)[HN(CH(2)CH(3))(3)](+).(CH(3)OH)(2)(CHCl(3)) (BA = benzoylacetone; Ln = Sm, 1; Eu, 2; Gd, 3; Dy, 4; Er, 5) were prepared by the reaction of hydrous lanthanide trichlorides with benzoylacetone in the presence of triethylamine in methanol and recrystallized from chloroform/methanol (1:10) at room temperature. These five compounds are isomorphous. Crystal data for 1: cubic, Pn3n; T = 180 K; a = 33.8652(4) A; V = 38838.4(8) A(3); Z = 6; D(calcd) = 1.125 g cm(-)(3); R1 = 3.37%. Crystal data for 2: cubic, Pn3n; T = 180 K; a = 33.8252(8) A; V = 38700.9(16) A(3); Z = 6; D(calcd) = 1.133 g cm(-)(3); R1 = 4.97%. Crystal data for 3: cubic, Pn3n; T = 180 K; a = 33.7061(6) A; V = 38293.5(12) A(3); Z = 6; D(calcd) = 1.157 g cm(-)(3); R1 = 5.13%. Crystal data for 4: cubic, Pn3n; T = 180 K; a = 33.5900(7) A; V = 37899.2(14) A(3); Z = 6; D(calcd) = 1.182 g cm(-)(3); R1 = 4.03%. Crystal data for 5: cubic, Pn3n; T = 180 K; a = 33.5054(8) A; V = 37613.6(16) A(3); Z = 6; D(calcd) = 1.202 g cm(-)(3); R1 = 4.86%. The core of the anionic cluster comprises two vertex-sharing square-pyramidal [Ln(5)(mu(4)-O)(mu(3)-OH)(4)](9+) units. The compounds were characterized by elemental analysis, IR, fast atom bombardment mass spectra, thermogravimetry, and differential scanning calorimetry. The thermal analysis indicated that the nonanuclear species were stable up to 150 degrees C. Luminescence spectra of 2 and magnetic properties of 1-5 were also studied. PMID:12470077

Xu, Gang; Wang, Zhe-Ming; He, Zheng; Lü, Zhi; Liao, Chun-Sheng; Yan, Chun-Hua

2002-12-16

408

The Partitioning of Americium and the Lanthanides Using Tetrabutyldiglycolamide (TBDGA) in Octanol and in Ionic Liquid Solution  

SciTech Connect

Separations among the lanthanides and the separation of Am from the lanthanides remain challenging, and research in this area continues to expand. The separation of adjacent lanthanides is of interest to high-tech industries because individual lanthanides have specialized uses and are in short supply. In nuclear fuel cycle applications Am would be incorporated into fast reactor fuels, yet the lanthanides are not desired. In this work the diamide N,N,N',N'-tetrabutyldiglycolamide (TBDGA) was investigated as a ligand for lanthanide and Am solvent extraction in both molecular and room temperature ionic liquid (RTIL) diluents. The RTIL [C4MIM][Tf2N-] showed very high extraction efficiency for these trivalent metals from low nitric acid concentrations, while the molecular diluent 1-octanol showed high extraction efficiency at high acid concentrations. This was attributed to the extraction of ionic nitrate complexes by the RTIL, whereas 1-octanol extracted neutral nitrate complexes. TBDGA in RTIL did not provide adequate separation factors for Am/lanthanide partitioning, but 1-octanol did show reasonable separation possibilities. Lanthanide intergroup separations appeared to be feasible in both diluents, but with higher separation factors from 1-octanol.

M.E. Mincher; D.L. Quach; Y.J. Liao; B.J. Mincher; C.M. Wai

2012-11-01

409

Determination of lanthanides in rock samples by inductively coupled plasma mass spectrometry using thorium as oxide and hydroxide correction standard  

NASA Astrophysics Data System (ADS)

Determination of lanthanides by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) using modified mathematical correction method has been studied. Normally, the ICP-MS analysis of middle and heavier lanthanides becomes difficult by severe spectroscopic overlap of M +, MO + or MOH + ions from lighter lanthanides and Ba. A correction method based on a single element oxide yield measurement, is a simple approach to correct for the above spectroscopic overlaps. But the uncertainty in the oxide and hydroxide yields measurement of lanthanides and barium over a long period of time can lead to inaccurate results even under fixed plasma conditions. To correct this, thorium was adopted as an oxide and hydroxide correction standard. Using a ratio of lanthanide oxide yield to thorium oxide yield, the lanthanide correction factors (LCF) were established and incorporated in the mathematical correction scheme. The same factors were also established for hydroxide correction. The proposed modified correction scheme was applied to the determination of lanthanides by ICP-MS from the USGS Standard Rock samples AGV-1 and G-2. The results are in good agreement with the reported values. The method also proved to be useful in isotopic ratio measurement of lanthanides having severe isobaric overlaps.

Raut, Narendra M.; Huang, Li-Shing; Aggarwal, Suresh K.; Lin, King-Chuen

2003-05-01

410

Liquid–liquid extraction of uranium and lanthanides from phosphoric acid using a synergistic DOPPA–TOPO mixture  

Microsoft Academic Search

Most of the phosphate rocks used commercially contain small quantities of metals such as uranium, lanthanides and yttrium. During the phosphate processing, by reacting the phosphate rocks with sulphuric acid, ca. 30% of lanthanide and yttrium and more than 80% of uranium, present initially in the rocks, end up in phosphoric acid. In this work the overall extraction of uranium

Mohamed Krea; Hussein Khalaf

2000-01-01

411

[Synthesis and characterization of new lanthanide complexes using pipemidic acid (PPA) and dioxane as ligands].  

PubMed

Eu(PPA)3 dioxane and Tb(PPA)3 dioxane were synthesized by firstly adopting dioxane as second ligand and using pipemidic acid (PPA) as first ligand. In contrast with two kinds of binary lanthanide complexes Eu(PPA)3 and Tb(PPA)3, the photoluminescent intensities of Eu (PPA)3 dioxane and Tb (PPA)3 dioxane are much stronger, especially for that of Tb(PPA)3 dioxane. The enhancement of photoluminescent intensities of Eu(PPA)3 dioxane and Tb(PPA)3 dioxane is because of the replacement of dioxane for water bonded to Eu3+ and Tb3+, by which the energy loss through heat oscillation will be inhibited. The as-synthesized lanthanide complexes were characterized by FT-IR, photoluminescence spectra and photoluminescence lifetime. The lifetime of Eu(PPA)3 dioxane and Tb(PPA) dioxane remarkably changed compared with those of Eu(PPA)3 and Tb(PPA)3. However, there is much difference for the lifetime change of as-synthesized lanthanide complexes formed by Eu3+ and Tb3+, which shows that there is different energy transfer process for the lanthanide complexes formed by Eu3+ and Tb3+. The synthesis of lanthanide complexes using dioxane as second ligand will provide a new method to detect the existence of dioxane. PMID:21595228

Cui, Yu-min; Tao, Dong-liang; Zhang, Wen-bao; Yin, Rong-can; Xu, Yi-zhuang; Wu, Jin-guang

2011-03-01

412

Spectroscopic properties and luminescence enhancement of lanthanide mixed complexes Ln? 3L in zirconia glasses  

NASA Astrophysics Data System (ADS)

The search for new compounds sensitizing lanthanides emission is of growing interest. Lanthanide mixed chelates of the type Ln? 3L (L-Lewis base; 2,2 '-bipyridine, 1.10-phenanthroline) seem to be promising in this area. In this work the new types of the lanthanide mixed chelates with phosphoro-azo-derivatives of ?-diketonates and 2,2 '-bipyridine were incorporated in zirconia glasses by the sol-gel techniques. The thin zirconia films were investigated at room temperature and at 77 K. The emission and excitation spectra, as well as the decay times, were recorded. Comparison is made with the respective spectroscopic data obtained for single crystals of the pure chelates. We found a dramatic increase of luminescence intensities of europium and terbium in the complexes as compared with the emission of lanthanide oxides in similar films. This effect is a result of the efficient exchange energy-transfer between the ligand and the lanthanide and the increase of rigidity of the complex incorporated in zirconia glasses. The necessary conditions for such transfer are discussed. These materials can find wide application as light conversion molecular devices, organic layered electroluminescence diodes (OLEDs) and in fluorimetric techniques.

Reisfeld, R.; Legendziewicz, J.; Puchalska, M.; Saraidarov, T.

2004-07-01

413

Coordination chemistry of several radius-sensitive complexones and applications to lanthanide-actinide separations  

SciTech Connect

The relationships between the lanthanide complex formation equilibria and the lanthanide-actinide separation application of three radius sensitive ligands have been studied. The consecutive stepwise formation constants of the 1:1, 2:1, and 3:1 chelate species formed by the interaction of DHDMB and the tripositive lanthanides and yttrium were determined potentiometrically at 0.1 M ionic strength and 25/sup 0/C. Results indicate that three different coordination modes, one tridentate and two bidentate are in evidence. Tracer level /sup 241/Am - /sup 155/Eu cation-exchange experiments utilizing DHDMB eluents indicate that this dihydroxycarboxylate does not form a sufficiently strong americium complex to elute that actinide ahead of europium. The overall stability of the americium 3:1 complex appears intermediate between samarium and europium. Cation-exchange elutions of /sup 241/Am, /sup 155/Eu, and /sup 160/Tb mixtures with EEDTA solutions prove that the EEDTA ligand is capable of eluting americium ahead of all of the tripositive lanthanide cations. The minimum separation occurs with terbium, where the Am-Tb separation factor is 1.71. 1,5-diaminopentane-N,N,N',N'-tetraacetic acid (PMDTA) was synthesized using cation exchange. A mathematical method was developed for the formation constants of the protonated and unprotonated lanthanide-PMDTA complexes from potentiometry. Cation-exchange elutions of tracer quantities of Am, Eu, and Tb revealed that terbium is eluted ahead of both americium and europium.

Potter, M.W.

1981-10-01

414

GLASS FABRICATION AND PRODUCT CONSISTENCY TESTING OF LANTHANIDE BOROSHILICATE FRIT X COMPOSITION FOR PLUTONIUM DISPOSITION  

SciTech Connect

The Department of Energy Office of Environmental Management (DOE/EM) plans to conduct the Plutonium Disposition Project at the Savannah River Site (SRS) to disposition excess weapons-usable plutonium. A plutonium glass waste form is the preferred option for immobilization of the plutonium for subsequent disposition in a geologic repository. A reference glass composition (Lanthanide Borosilicate (LaBS) Frit B) was developed during the Plutonium Immobilization Program (PIP) to immobilize plutonium in the late 1990's. A limited amount of performance testing was performed on this baseline composition before efforts to further pursue Pu disposition via a glass waste form ceased. Recent FY05 studies have further investigated the LaBS Frit B formulation as well as development of a newer LaBS formulation denoted as LaBS Frit X. The objectives of this present task were to fabricate plutonium loaded LaBS Frit X glass and perform corrosion testing to provide near-term data that will increase confidence that LaBS glass product is suitable for disposal in the Yucca Mountain Repository. Specifically, testing was conducted in an effort to provide data to Yucca Mountain Project (YMP) personnel for use in performance assessment calculations. Plutonium containing LaBS glass with the Frit X composition with a 9.5 wt% PuO{sub 2} loading was prepared for testing. Glass was prepared to support Product Consistency Testing (PCT) at Savannah River National Laboratory (SRNL). The glass was thoroughly characterized using x-ray diffraction (XRD) and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS) prior to performance testing. A series of PCTs were conducted at SRNL using quenched Pu Frit X glass with varying exposed surface areas. Effects of isothermal and can-in-canister heat treatments on the Pu Frit X glass were also investigated. Another series of PCTs were performed on these different heat-treated Pu Frit X glasses. Leachates from all these PCTs were analyzed to determine the dissolved concentrations of key elements. Acid stripping of leach vessels was performed to determine the concentration of the glass constituents that may have sorbed on the vessels during leach testing. Additionally, the leachate solutions were ultrafiltered to quantify colloid formation. Characterization of the quenched Pu Frit X glass prior to testing revealed that some crystalline plutonium oxide was present in the glass. The crystalline particles had a disklike morphology and likely formed via coarsening of particles in areas compositionally enriched in plutonium. Similar results had also been observed in previous Pu Frit B studies. Isothermal 1250 C heat-treated Pu Frit X glasses showed two different crystalline phases (PuO{sub 2} and Nd{sub 2}Hf{sub 2}O{sub 7}), as well as a peak shift in the XRD spectra that is likely due to a solid solution phase PuO{sub 2}-HfO{sub 2} formation. Micrographs of this glass showed a clustering of some of the crystalline phases. Pu Frit X glass subjected to the can-in-canister heating profile also displayed the two PuO{sub 2} and Nd{sub 2}Hf{sub 2}O{sub 7} phases from XRD analysis. Additional micrographs indicate crystalline phases in this glass were of varying forms (a spherical PuO{sub 2} phase that appeared to range in size from submicron to {approx}5 micron, a dendritic-type phase that was comprised of mixed lanthanides and plutonium, and a minor phase that contained Pu and Hf), and clustering of the phases was also observed.

Marra, J

2006-11-21

415

A cell-based time-resolved fluorescence assay for selection of antibody reagents for G protein-coupled receptor immunohistochemistry.  

PubMed

A cell-based time-resolved fluorescence (celTRF) immunoassay is described for pre-screening antibodies to G protein-coupled receptor (GPCR) peptides that predicts suitability for immunohistochemistry (IHC). Rat GPCRs were expressed in Saos-2 human osteosarcoma cells via recombinant baculoviruses designed for mammalian cell expression, i.e., the transduced cells were used as a "screening lawn". The lawn was fixed and permeabilized similarly to IHC tissue. The celTRF, a dissociation-enhanced lanthanide fluorescence immunoassay (DELFIA), employed Eu-labelled goat anti-rabbit IgG. It exhibited a broad dynamic range upon which enzyme-linked immunosorbant assay (ELISA)-positive affinity-purified anti-peptide antibody reagents were examined for specificity and potency. Over 150 anti-peptide reagents to 27 GPCRs were characterized. All celTRF-positive antibodies were found to be suitable for IHC, whereas ELISA alone did not predict IHC utility. Examples are illustrated with five rabbit anti-neuropeptide FF receptor 1 (NPFF1) antibodies, where a strong correlation between celTRF potency and IHC utility was observed in both applications. In contrast, two high anti-peptide ELISA titer but celTRF-negative antibodies failed to recognize the NPFF1 receptor in IHC. The celTRF assay was performed manually and in an automated fashion, in our case, using a Biomek FX station and Sami scheduling software. The celTRF is the first in vitro automated assay that offers confident pre-selection of antibodies for IHC and the versatility to accommodate the rapid screening of large numbers of GPCRs. The celTRF is readily applicable to other protein target classes. PMID:15345311

Su, Jui-Lan; Fornwald, Jim; Rivers, Philip; Goldsworthy, Susan; Looney, Noeleen A; Hanvey, Jeff; Plumpton, Chris; Parham, Janet; Romanos, Michael; Kost, Thomas A; Kull, Frederick C

2004-08-01

416

Methods and apparatuses for reagent delivery, reactive barrier formation, and pest control  

DOEpatents

A reagent delivery method includes positioning reagent delivery tubes in contact with soil. The tubes can include a wall that is permeable to a soil-modifying reagent. The method further includes supplying the reagent in the tubes, diffusing the reagent through the permeable wall and into the soil, and chemically modifying a selected component of the soil using the reagent. The tubes can be in subsurface contact with soil, including groundwater, and can be placed with directional drilling equipment independent of groundwater well casings. The soil-modifying reagent includes a variety of gases, liquids, colloids, and adsorbents that may be reactive or non-reactive with soil components. The method may be used inter alia to form reactive barriers, control pests, and enhance soil nutrients for microbes and plants.

Gilmore, Tyler [Pasco, WA; Kaplan, Daniel I [Aiken, SC; Last, George [Richland, WA

2002-07-09

417

Stability study for magnetic reagent assaying Hb and HbA1c  

NASA Astrophysics Data System (ADS)

Reagents for magnetically labeled immunoassay on human Hb and human HbA1c have been synthesized. The reagents consist of Fe3O4 magnetic particles biofunctionalized with antibodies against Hb and HbA1c. It has been demonstrated that the reagents can be applied to quantitatively detect Hb and HbA1c by using immunomagnetic reduction assay. In addition to characterizing the assay properties, such as the standard curve and the low-detection limit, the stability of reagents is investigated. To do this, the temporal dependence of particle sizes and the bio-activity of reagents are monitored. The results show that the reagents are highly stable when stored at 2-8 °C. This means that the reagents synthesized in this work are promising for practical applications.

Hsieh, Wen-Pin; Chieh, J. J.; Yang, C. C.; Yang, S. Y.; Chen, Po-Yu; Huang, Yu-Hao; Hong, Y. W.; Horng, H. E.

2013-01-01

418

Synthetic gauge field with highly magnetic lanthanide atoms  

NASA Astrophysics Data System (ADS)

We present a scheme for generating a synthetic magnetic field and spin-orbit coupling via Raman coupling in highly magnetic lanthanide atoms such as dysprosium. Employing these atoms offers several advantages for realizing strongly correlated states and exotic spinor phases. The large spin and narrow optical transitions of these atoms allow the generation of synthetic magnetic fields that are an order of magnitude larger than those in the alkali metals, but with considerable reduction of the heating rate for equal Raman coupling. The effective Hamiltonian of these systems differs from that of the alkali metals' by an additional nematic coupling term, which leads to a phase transition in the dressed states as detuning varies. For high-spin condensates, spin-orbit coupling leads to a spatially periodic structure, which is described in a Majorana representation by a set of points moving periodically on a unit sphere. We name this a “Majorana spinor helix,” in analogy to the persistent spin-(1)/(2) helix observed in electronic systems.

Cui, Xiaoling; Lian, Biao; Ho, Tin-Lun; Lev, Benjamin L.; Zhai, Hui

2013-07-01

419

Effect of lanthanide complex structure on cell viability and association.  

PubMed

A systematic study of the effect of hydrophobicity and charge on the cell viability and cell association of lanthanide metal complexes is presented. The terbium luminescent probes feature a macrocyclic polyaminocarboxylate ligand (DOTA) in which the hydrophobicity of the antenna and that of the carboxyamide pendant arms are independently varied. Three sensitizing antennas were investigated in terms of their function in vitro: 2-methoxyisophthalamide (IAM(OMe)), 2-hydroxyisophthalamide (IAM), and 6-methylphenanthridine (Phen). Of these complexes, Tb-DOTA-IAM exhibited the highest quantum yield, although the higher cell viability and more facile synthesis of the structurally related Tb-DOTA-IAM(OMe) platform renders it more attractive. Further modification of this latter core structure with carboxyamide arms featuring hydrophobic benzyl, hexyl, and trifluoro groups as well as hydrophilic amino acid based moieties generated a family of complexes that exhibit high cell viability (ED50 > 300 ?M) regardless of the lipophilicity or the overall complex charge. Only the hexyl-substituted complex reduced cell viability to 60% in the presence of 100 ?M complex. Additionally, cellular association was investigated by ICP-MS and fluorescence microscopy. Surprisingly, the hydrophobic moieties did not increase cell association in comparison to the hydrophilic amino acid derivatives. It is thus postulated that the hydrophilic nature of the 2-methoxyisophthalamide antenna (IAM(OMe)) disfavors the cellular association of these complexes. As such, responsive luminescent probes based on this scaffold would be appropriate for the detection of extracellular species. PMID:24901440

Peterson, Katie L; Dang, Jonathan V; Weitz, Evan A; Lewandowski, Cutler; Pierre, Valérie C

2014-06-16

420

Differential dual-beam thermal lensing spectrometry: Determination of lanthanides  

SciTech Connect

This paper describes a differential dual-beam thermal lensing setup which involves two continuous lasers and two cells placed one just behind the other on the beampath. A tunable excitation laser creates the thermal lensing effect in two cells, whereas the (He-Ne) laser, collinear to the excitation beam, probes the variation of the index of refraction due to the absorption in each cell. The differential response is achieved by placing the solvent in the first cell and the solvent with analyte in the second cell. The positions of the two cuvettes are optimized in order to maximize differential thermal lensing effect detection. This differential instrument allows compensation of 95--98% of the thermal lensing solvent effect. Thermal lensing spectra of two lanthanide ions (Nd/sup 3 +/, Pr/sup 3 +/), both in no complexing solution (HClO/sub 4/) and in carbonate medium, are discussed. Analytical determinations of these elements with detection limits in the range of 10/sup -6/ mole per liter are observed.

Berthoud, T.; Delorme, N.

1987-01-01

421

Molecular Magnets Based on Homometallic Hexanuclear Lanthanide(III) Complexes.  

PubMed

The reaction of lanthanide(III) chloride salts (Gd(III), Dy(III), Tb(III), and Ho(III)) with the hetero donor chelating ligand N'-(2-hydroxy-3-methoxybenzylidene)-6-(hydroxymethyl)picolinohydrazide (LH3) in the presence of triethylamine afforded the hexanuclear Ln(III) complexes [{Ln6(L)2(LH)2}(?3-OH)4][MeOH]p[H2O]q[Cl]4·xH2O·yCH3OH (1, Ln = Gd(III), p = 4, q = 4, x = 8, y = 2; 2, Ln = Dy(III), p = 2, q = 6, x = 8, y = 4; 3, Ln = Tb(III), p = 2, q = 6, x = 10, y = 4; 4, Ln = Ho(III), p = 2, q = 6, x = 10, y = 2). X-ray diffraction studies revealed that these compounds possess a hexanuclear [Ln6(OH)4](14+) core consisting of four fused [Ln3(OH)](8+) subunits. Both static (dc) and dynamic (ac) magnetic properties of 1-4 have been studied. Single-molecule magnetic behavior has been observed in compound 2 with an effective energy barrier and relaxation time pre-exponential parameters of ?/kB = 46.2 K and ?0 = 2.85 × 10(-7) s, respectively. PMID:24766539

Das, Sourav; Hossain, Sakiat; Dey, Atanu; Biswas, Sourav; Sutter, Jean-Pascal; Chandrasekhar, Vadapalli

2014-05-19

422

Highly Luminescent Lanthanide Complexes of 1 Hydroxy-2-pyridinones  

SciTech Connect

The synthesis, X-ray structure, stability, and photophysical properties of several trivalent lanthanide complexes formed from two differing bis-bidentate ligands incorporating either alkyl or alkyl ether linkages and featuring the 1-hydroxy-2-pyridinone (1,2-HOPO) chelate group in complex with Eu(III), Sm(III) and Gd(III) are reported. The Eu(III) complexes are among some of the best examples, pairing highly efficient emission ({Phi}{sub tot}{sup Eu} {approx} 21.5%) with high stability (pEu {approx} 18.6) in aqueous solution, and are excellent candidates for use in biological assays. A comparison of the observed behavior of the complexes with differing backbone linkages shows remarkable similarities, both in stability and photophysical properties. Low temperature photophysical measurements for a Gd(III) complex were also used to gain insight into the electronic structure, and were found to agree with corresponding TD-DFT calculations for a model complex. A comparison of the high resolution Eu(III) emission spectra in solution and from single crystals also revealed a more symmetric coordination geometry about the metal ion in solution due to dynamic rotation of the observed solid state structure.

University of California, Berkeley; Lawrence National Laboratory; Raymond, Kenneth; Moore, Evan G.; Xu, Jide; Jocher, Christoph J.; Castro-Rodriguez, Ingrid; Raymond, Kenneth N.

2007-11-01

423

PLUTONIUM FEED IMPURITY TESTING IN A LANTHANIDE BOROSILICATE (LABS) GLASS  

SciTech Connect

A vitrification technology utilizing a lanthanide borosilicate (LaBS) glass is a viable option for dispositioning excess weapons-useable plutonium that is not suitable for processing into mixed oxide (MOX) fuel. A significant effort to develop a glass formulation and vitrification process to immobilize plutonium was completed in the mid-1990s. The LaBS glass formulation was found to be capable of immobilizing in excess of 10 wt % Pu and to be tolerant of a range of impurities. A more detailed study is now needed to quantify the ability of the glass to accommodate the anticipated impurities associated with the Pu feeds now slated for disposition. The database of Pu feeds was reviewed to identify impurity species and concentration ranges for these impurities. Based on this review, a statistically designed test matrix of glass compositions was developed to evaluate the ability of the LaBS glass to accommodate the impurities. Sixty surrogate LaBS glass compositions were prepared in accordance with the statistically designed test matrix. The heterogeneity (e.g. degree of crystallinity) and durability (as measured by the Product Consistency Test - Method A (PCT-A)) of the glasses were used to assess the effects of impurities on glass quality.

Marra, J; Kevin Fox, K; Elizabeth Hoffman, E; Tommy Edwards, T; Charles Crawford, C

2007-08-29

424

STEM Colorado: Doppler Shift  

NSDL National Science Digital Library

This applet demonstrates the Doppler shift. The user can control the frequency of the sound source and the sound speed. The chart recorder at the bottom displays the wave crests as detected by the receiver and their frequency. It also displays the instantaneous wavelength if the ear is at rest. The user can drag the source or the receiver to any location in the display and choose the velocity of each. This is part of a larger collection of applets by STEM Colorado focused mostly on topics in astronomy.

Mccray, Richard; Koelemay, Andrew

2008-08-30

425

Selective extraction of trivalent actinides from lanthanides with dithiophosphinic acids and tributylphosphate  

SciTech Connect

A variety of chemical systems have been developed to separate trivalent actinides from lanthanides based on the slightly stronger complexation of the trivalent actinides with ligands that contain soft donor atoms. The greater stability of the actinide complexes in these systems has often been attributed to a slightly greater covalent bonding component for the actinide ions relative to the lanthanide ions. The authors have investigated several synergistic extraction systems that use ligands with a combination of oxygen and sulfur donor atoms that achieve a good group separation of the trivalent actinides and lanthanides. For example, the combination of dicyclohexyldithiophosphinic acid and tributylphosphate has shown separation factors of up to 800 for americium over europium in a single extraction stage. Such systems could find application in advanced partitioning schemes for nuclear waste.

Jarvinen, G.; Barrans, R.; Schroeder, N.; Wade, K.; Jones, M.; Smith, B.F. [Los Alamos National Lab., NM (United States); Mills, J.; Howard, G. [Texas Tech Univ., Lubbock, TX (United States); Freiser, H.; Muralidharan, S. [Arizona Univ., Tucson, AZ (United States)

1995-01-01

426

Improved separation of Am(III) from the light lanthanides using a soft-donor synergist  

SciTech Connect

The separation of minor actinides from fission products, especially the trivalent lanthanides, remains a difficult problem. Current research has focused on the use of soft-donor groups that have a greater affinity for the trivalent actinides than for the lanthanides. The extractant bis(chlorophenyl)dithio-phosphinic acid was used in combination with a synergist, 4,7-diphenyl- 1,10-phenanthroline, to extract Am(III) and Eu(III) from aqueous nitrate media. The extraction efficiencies of Am(III) and Eu(III) were measured by varying the total ionic strength and concentrations of the extractant, synergist, and nitric acid. Results suggest that this synergistic system may be useful for group separation of the minor actinides from the lanthanides. (authors)

Ensor, Dale D.; Zimmerman, Matthew H. [Chemistry Department, Tennessee Technological University, Cookeville, TN 38505 (United States)

2008-07-01

427

Average electronegativity, electronic polarizability and optical basicity of lanthanide oxides for different coordination numbers  

NASA Astrophysics Data System (ADS)

On the basis of new electronegativity values, electronic polarizability and optical basicity of lanthanide oxides are calculated from the concept of average electronegativity given by Asokamani and Manjula. The estimated values are in close agreement with our previous conclusion. Particularly, we attempt to obtain new data of electronic polarizability and optical basicity of lanthanide sesquioxides for different coordination numbers (6-12). The present investigation suggests that both electronic polarizability and optical basicity increase gradually with increasing coordination number. We also looked for another double peak effect, that is, electronic polarizability and optical basicity of trivalent lanthanide oxides show a gradual decrease and then an abrupt increase at the Europia and Ytterbia. Furthermore, close correlations are investigated among average electronegativity, optical basicity, electronic polarizability and coordination number in this paper.

Zhao, Xinyu; Wang, Xiaoli; Lin, Hai; Wang, Zhiqiang

2008-05-01

428

Luminescence of trivalent lanthanide ions excited by single-bubble and multibubble cavitations.  

PubMed

This article focuses on the possibility of exciting some lanthanides (Ce(3+), Tb(3+), Gd(3+), and Eu(3+)) by ultrasound in aqueous solutions. Depending on the lanthanide ions and on the acoustic cavitation conditions (single-bubble or multibubble systems), the excitation mechanism is shown to be photoexcitation (e.g., for Ce(3+)) or collision-induced excitation (e.g., for Tb(3+)). The sonoluminescence of Tb(3+) is studied in detail at various ultrasonic frequencies, allowing quantification of the amount of quenching. The latter is much stronger in sonoluminescence than in photoluminescence due to the particular properties of acoustic cavitation. Complexation with citrate ions enhances manifold sonoluminescence of lanthanides due to reduction of intra- and inner-molecular quenching. PMID:23421489

Pflieger, Rachel; Schneider, Julia; Siboulet, Bertrand; Möhwald, Helmuth; Nikitenko, Sergey I

2013-03-14

429

Extraction of tervalent lanthanides as hydroxide complexes with tri-n-octylphosphine oxide  

SciTech Connect

The extraction behavior of lanthanum(III), praseodymium(III), europium(III), terbium(III), holmium(III), and ytterbium(III) from dilute chloride solutions into chloroform solutions containing tri-n-octylphosphine oxide (TOPO) was examined. The lanthanides were found to extract as hydroxide complexes of the form Ln(OH){sub 3}{center dot}nTOPO. The extraction selectivity for this system increases with increasing TOPO concentration, rivaling those for common acidic organophosphorus extractants in the TOPO concentration range 0.025-0.100 M and surpassing them at higher concentrations. When TOPO concentrations of 0.25 M or greater are employed, the extraction system is, overall, the most selective for lanthanide separations to date. This is the first report of the lanthanides extracting as hydroxide complexes.

Cecconie, T.; Freiser, H. (Univ. of Arizona, Tucson (USA))

1990-03-15

430

Ozone Sensitivity to Emissions and Changes of Limiting Reagents  

NASA Astrophysics Data System (ADS)

Regional control strategy options for reducing ozone change temporally and spatially in Central California where air pollution is particularly serious. The rate of ozone production is a complex function of the concentrations of volatile organic compounds (VOCs) and nitrogen oxides (NOx) as well as meteorological conditions. As a result, ozone formation exhibits a very non-linear dependence on its precursors. Determining the relative benefits of controlling NOx emissions or VOC emissions remains a challenging problem. Current practice of modeling 3 to 5 day episodes does not capture the changes in limiting reagents since they represent a limited sample of the diverse meteorology and human behavior that affect air pollution. We are using CMAQ, the EPA's Community Multiscale Air Quality Model, to model a season of air quality in Central California for the summer of 2000 to illustrate some limitations of current practice. We have modeled a 15-day period and, in concert with the modeling, have also used the Decoupled Direct Method to compute ozone sensitivities to NOx emissions and VOC emissions. The emissions have been disaggregated differently to extract mechanistic information regarding limiting reagents, and to explore issues of long range transport. We have computed ozone sensitivities to total NOx emissions and VOC emissions for the entire modeling domain, NOx emissions and VOC emissions from specific air basins, as well as emissions from specific air basins for specific time intervals. We demonstrate how the computed sensitivity coefficients of ozone to the various emission types and consideration of meteorology may be used to demonstrate and understand limiting reagent changes throughout the modeling domain.

Brown, N. J.; Jin, L.; Tonse, S.; Harley, R. A.

2006-12-01

431

Chemical interaction matrix between reagents in a Purex based process  

SciTech Connect

The United States Department of Energy (DOE) is the responsible entity for the disposal of the United States excess weapons grade plutonium. DOE selected a PUREX-based process to convert plutonium to low-enriched mixed oxide fuel for use in commercial nuclear power plants. To initiate this process in the United States, a Mixed Oxide (MOX) Fuel Fabrication Facility (MFFF) is under construction and will be operated by Shaw AREVA MOX Services at the Savannah River Site. This facility will be licensed and regulated by the U.S. Nuclear Regulatory Commission (NRC). A PUREX process, similar to the one used at La Hague, France, will purify plutonium feedstock through solvent extraction. MFFF employs two major process operations to manufacture MOX fuel assemblies: (1) the Aqueous Polishing (AP) process to remove gallium and other impurities from plutonium feedstock and (2) the MOX fuel fabrication process (MP), which processes the oxides into pellets and manufactures the MOX fuel assemblies. The AP process consists of three major steps, dissolution, purification, and conversion, and is the center of the primary chemical processing. A study of process hazards controls has been initiated that will provide knowledge and protection against the chemical risks associated from mixing of reagents over the life time of the process. This paper presents a comprehensive chemical interaction matrix evaluation for the reagents used in the PUREX-based process. Chemical interaction matrix supplements the process conditions by providing a checklist of any potential inadvertent chemical reactions that may take place. It also identifies the chemical compatibility/incompatibility of the reagents if mixed by failure of operations or equipment within the process itself or mixed inadvertently by a technician in the laboratories. (aut0010ho.

Brahman, R.K.; Hennessy, W.P. [Shaw AREVA MOX Services, LLC (United States); Paviet-Hartmann, P. [Idaho State University/Idaho National Laboratory (United States)

2008-07-01

432

Silver nanoparticles incorporated onto ordered mesoporous silica from Tollen's reagent  

NASA Astrophysics Data System (ADS)

Noble metal nanostructures supported on mesoporous silica are bridge between traditional silica adsorbents and modern catalysts. In this work the Ag/SBA-15 mesoporous materials were synthesized and characterized. Various forms of nanosilver supported on ordered mesoporous template have been successfully obtained via proposed procedures. In all synthesized materials, Tollen's reagent (diammine silver complex [Ag(NH3)2]+) was used as a silver source. Silver nanoparticles were prepared by reduction of ammoniacal silver complex by formaldehyde in the solution of stabilizer. After reduction, Ag nanoparticles could be deposited on SBA-15, or added during traditional synthesis of SBA-15 giving silver or silver chloride nanoparticles in the combination with porous silica. Silver nanostructures as nanoparticles or nanowires were also embedded onto the SBA-15 by incipient wetness impregnation of silver ions. Absorbed silver ions were next reduced under hydrogen at high temperature. There are many advantages of utilized ammoniacal silver complex as a silver source. Proposed method is capable to synthesis of various metal nanostructures with controlled composition and morphology. The silver ammonia complex is composed of two ions surrounding and protecting the central silver ion, so it is possible to obtain very small nanoparticles using simple approach without any functionalization of external and internal surface of SBA-15. This approach allows obtaining greatly small silver nanoparticles on SBA-15 (4 nm) or nanowires depending on the metal loading amount. Moreover, the colloidal silver solution prepared from Tollen's reagent, in the presence of triblock copolymer, remains stable for a long time. Reduction of Tollen's reagent to silver colloidal solution seems to be efficient, fast and interesting approach for the preparation of supported silver nanostructures Obtained samples were characterized by powder X-ray diffraction, small angle X-ray scattering (SAXS), UV-vis spectroscopy, transmission electron microscopy (TEM), nitrogen adsorption-desorption isotherms and photoacoustic spectroscopy (PAS).

Zienkiewicz-Strza?ka, M.; Pasieczna-Patkowska, S.; Kozak, M.; Pikus, S.

2013-02-01

433

[Sludge dewaterability with combined conditioning using Fenton's reagent and CPAM].  

PubMed

The moisture of sludge significantly influenced its dewaterability and the disposal cost. Cationic polyacrylamide (CPAM) and Fenton's reagent were investigated for sludge dewatering with separate and combined conditioning. Several parameters were used to evaluate the dewatering performance and to analyze the conditioning mechanism, such as cake moisture, soluble COD, protein and polysaccharide contents in supernatant and sludge particle size. The results indicated that favorable dewaterability was achieved when the sludge was conditioned at higher CPAM degrees, and sludge dewatering ability was further improved at acidic conditions. In Fenton reaction, higher H2O2 dosages enhanced the dewatering performance of sludge. Combined conditioning using Fenton's reagent and CPAM led to considerable improved sludge dewaterability. At the optimized dosages of FeSO4 (2 g x L(-1)) and H2O2 (6 g x L(-1)), the sludge moisture declined to 76.7% from 85.5% (raw sludge), while a moisture as low as 74.8% was obtained by combined conditioning using CPAM (3 kg x t(-1)). Sludge particle size went down and the specific surface area grew bigger after Fenton reaction. As a result of disintegration of extracellular polymeric substances (EPS), the adsorbed and intrinsic water were released from microorganisms and sludge flocs. CPAM addition remarkably promoted the coagulating and flocculating of dispersed flocs. Sludge particle size changed from 35.16 microm to 50.50 microm, and the specific surface area declined from 0.39 m2 x g(-1) to 0.20 m2 x g(-1). The combined conditioning using Fenton's reagent and CPAM was proved to be more effective in improving sludge dewaterability, compared with the separate conditioning. PMID:24289002

Ma, Jun-wei; Liu, Jie-wei; Cao, Rui; Yue, Dong-bei; Wang, Hong-tao

2013-09-01

434

Phase-Shift Effect Magnetometer.  

National Technical Information Service (NTIS)

The primary objective of the research project was to determine the feasibility of using phase shift phenomenon as the transducing principal of a magnetometer. The findings show that, not only is a phase shift effect magnetometer possible, but high sensiti...

R. C. Dinsmore

1991-01-01

435

Thermodynamic and spectroscopic studies of lanthanides(III) complexation with polyamines in dimethyl sulfoxide.  

PubMed

The thermodynamic parameters of complexation of Ln(III) cations with tris(2-aminoethyl)amine (tren) and tetraethylenepentamine (tetren) were determined in dimethyl sulfoxide (DMSO) by potentiometry and calorimetry. The excitation and emission spectra and luminescence decay constants of Eu3+ and Tb3+ complexed by tren and tetren, as well as those of the same lanthanides(III) complexed with diethylenetriamine (dien) and triethylenetetramine (trien), were also obtained in the same solvent. The combination of thermodynamic and spectroscopic data showed that, in the 1:1 complexes, all nitrogens of the ligands are bound to the lanthanides except in the case of tren, in which the pendant N is bound. For the larger ligands (trien, tren, tetren) in the higher complexes (ML2), there was less complete binding by available donors, presumably due to steric crowding. FT-IR studies were carried out in an acetonitrile/DMSO mixture, suitably chosen to follow the changes in the primary solvation sphere of lanthanide(III) due to complexation of amine groups. Results show that the mean number of molecules of DMSO removed from the inner coordination sphere of lanthanides(III) is lower than ligand denticity and that the coordination number of the metal ions increases with amine complexation from approximately 8 to approximately 10. Independently of the number and structure of the amines, linear trends, similar for all lanthanides, were obtained by plotting the values of DeltaGj degrees, DeltaHj degrees, and TDeltaSj degrees for the complexation of ethylenediamine (en), dien, trien, tren, and tetren as a function of the number of amine metal-coordinated nitrogen atoms. The main factors on which the thermodynamic functions of lanthanide(III) complexation reactions in DMSO depend are discussed. PMID:18166040

Di Bernardo, P; Zanonato, P L; Melchior, A; Portanova, R; Tolazzi, M; Choppin, G R; Wang, Z

2008-02-01

436

Near-infrared reagents for fibre-optic ammonia sensors  

Microsoft Academic Search

Representatives of three types of near-infrared dyes, i.e., Cu(II) complex of 5-(N?-diethylamino-phenylimino)quinoline-8-one (D1), NIR acid-base indicator 1,5-bis-[p-dimethylamino-phenyl]-divinylene-carbenium-perchlorate (D2) and squaraine dye (D3), have been tested as reagents for fibre-optic ammonia sensors. Both D1 and D2 show reversible response to ammonia and are thus suitable for the monitoring of gas ammonia. D1 has low stability and hence cannot be easily incorporated

P. Šimon; S. Sekretár; B. D. MacCraith; F. Kvasnik

1997-01-01

437

An amino acid-based heterofunctional cross-linking reagent.  

PubMed

We describe the synthesis and characterization of a new lysine-based heterofunctional cross-linking reagent. It carries two readily available aminooxy functionalities and an activated and protected thiol group that is capable of generating reducible disulfides, the former enable bioorthogonal modification of ketones and aldehydes by the formation of an oxime bond. The efficacy of the linker was proven by coupling two doxorubicin molecules to the functionalized amino acid core and the subsequent bioconjugation of this drug conjugate with a thiolated antibody. PMID:24504931

Lelle, Marco; Peneva, Kalina

2014-05-01

438

SPECTROPHOTOMETRIC DETERMINATION OF COPPER AND PALLADIUM USING A NEW REAGENT  

Microsoft Academic Search

Highly sensitive spectrophotometric methods for determination of copper and palladium by a new synthesized chromogenic reagent N-dodecyl-N?-(sodium p-amino-benzenesulfonate)-thiourea (DOPT) were developed. In the presence of CTMAB and NaAc-HAc buffer solution, under the optimum conditions for color reaction of copper and palladium with DOPT, their molar absorptivities are ?300.4 nm = 1.56 × 10 l mol cm at 300.4 nm for copper and ?296.0 nm = 7.41

Donglan Ma; Fengling Cui; Dongsheng Xia; Yulu Wang

2002-01-01

439

Palladium pincer complex-catalyzed allylic stannylation with hexaalkylditin reagents.  

PubMed

Palladium pincer complex (1)-catalyzed stannylation of allyl chloride, phosphonate, and epoxide substrates (4a-h) could be performed with hexaalkylditin reagents (3) under mild neutral reaction conditions. This catalytic reaction proceeds via palladium(II) intermediates without involvement of allyl-palladium complexes, and therefore the allylstannane product does not interfere with the palladium catalyst. Use of a combined catalytic system (1 + 2) allowed the development of an effective one-pot procedure for allylation of aldehyde and imine electrophiles. [reaction: see text] PMID:15151425

Wallner, Olov A; Szabó, Kálmán J

2004-05-27

440

Surface electric properties of emulsions of apolar reagents  

SciTech Connect

This article presents the results of studies of surface electric properties of kerosene and AAR-2 (apolar aromatized reagent) emulsons in water, which can be used in coal slime flotation, in presence of various salts and high-molecular flocculants. The data obtained were compared with the effect of electrolytes on the surface electric properties of a model emulsion of heptane in water stabilized by sodium hapthenate. The studies indicate that similarity of changes in the electrokinetic properties of various emulsions in presence of electrolytes and flocculants.

Baichenko, A.A.; Baran, A.A.

1986-09-01

441

Even-shift orthogonal sequences  

Microsoft Academic Search

A class of binary sequences whose elements are either1or-1and whose autocorrelation function is0for all even shifts except the zero shift is discussed. These sequences will be calledEsequences. It is proved that everyEsequence is paired with anotherEsequence, its mate, so that the cross-correlation function between them is0for all even shifts including the zero shift. Using these sequences, new complete orthogonal function

Y. Taki; H. Miyakawa; M. Hatori; S. Namba

1969-01-01

442

Lanthanide(III)/pyrimidine-4,6-dicarboxylate/oxalate extended frameworks: a detailed study based on the lanthanide contraction and temperature effects.  

PubMed

Detailed structural, magnetic, and luminescence studies of six different crystalline phases obtained in the lanthanide/pyrimidine-4,6-dicarboxylate/oxalate system have been afforded: {[Ln(?-pmdc)(?-ox)(0.5)(H(2)O)(2)]·3H(2)O}(n) (1-Ln), {[Ln(?-pmdc)(?-ox)(0.5)(H(2)O)(3)]·2H(2)O}(n) (2-Ln), {[Ln(?(3)-pmdc)(?-ox)(0.5)(H(2)O)(2)]·~2.33H(2)O}(n) (3-Ln), {[Ln(2)(?(3)-pmdc)(?(4)-pmdc)(?-ox)(H(2)O)(3)]·5H(2)O}(n) (4-Ln), {[Ln(?(3)-pmdc)(?-ox)(0.5)(H(2)O)(2)]·H(2)O}(n) (5-Ln), and [Ln(pmdc)(1.5)(H(2)O)(2.5)] (6-Ln). The slow generation of the oxalate (ox) anion, obtained from the in situ partial hydrothermal decomposition of the pyrimidine-4,6-dicarboxylate (pmdc) ligand, allows us to obtain good shaped single crystals, while direct addition of potassium oxalate provides the same compounds but as polycrystalline samples. The crystal structures of all compounds are based on the double chelation established by the pmdc and ox ligands to provide distorted 2D honeycomb layers that, in some cases, are fused together, leading to 3D systems, by replacing some of the coordinated water molecules that complete the coordination sphere of the lanthanide by uncoordinated carboxylate oxygen atoms of the pmdc. The presence of channels occupied by crystallization water molecules is also a common feature with the exception of compounds 5-Ln. It is worth noting that compounds 3-Ln present a commensurate crystal structure related to the partial occupancy of the crystallization water molecules placed within the channels. Topological analyses have been carried out, showing a previously nonregistered topology for compounds 4-Ln, named as jcr1. The crystal structures are strongly dependent on the lanthanide ion size and the temperature employed during the hydrothermal synthesis. The lanthanide contraction favors crystal structures involving sterically less hindranced coordination environments for the final members of the lanthanide series. Additionally, reinforcement of the entropic effects at high temperatures directs the crystallization process toward less hydrated crystal structures. The magnetic data of these compounds indicate that the exchange coupling between the lanthanide atoms is almost negligible, so the magnetic behavior is dominated by the spin-orbit coupling and the ligand field perturbation. The luminescence properties that exhibit the compounds containing Nd(III), Eu(III), and Tb(III) have been also characterized. PMID:21800833

Cepeda, Javier; Balda, Rolindes; Beobide, Garikoitz; Castillo, Oscar; Fernández, Joaquín; Luque, Antonio; Pérez-Yáñez, Sonia; Román, Pascual; Vallejo-Sánchez, Daniel

2011-09-01

443

Labelling of silica microspheres with fluorescent lanthanide-doped LaF3 nanocrystals  

NASA Astrophysics Data System (ADS)

Fluorescent microspheres have been demonstrated to be useful in a variety of biological applications. Fluorescent silica or polymer microspheres have been produced by incorporation of chromophores into the microspheres, which usually produces microspheres with nonuniform sizes and reduced fluorescence. Here we present a simple and straightforward method to produce silica microspheres with fluorescent lanthanide-doped LaF3 nanocrystals grown on the surface. LaF3 nanocrystals are in situ grown on silica microspheres of different sizes to form a raspberry-like structure. The microspheres exhibit strong fluorescence and the colour could be altered by changing the lanthanide ions doped in LaF3 nanocrystals.

Zhang, Yong; Lu, Meihua

2007-07-01

444

Trivalent lanthanide ions do not cleave RNA in DNA-RNA hybrids  

SciTech Connect

Lanthanide(III) complexes rapidly catalyze cleavage of single-stranded RNA. RNA cleavage by lanthanide complexes is, however, dependent on RNA structure. A DNA-RNA hybrid formed by annealing a complementary oligodeoxynucleotide to t-RNA[sup phe] is found to be inert to cleavage by a europium(III) hexadentate Schiff base complex and by Eu(CO[sub 2]CH[sub 3])[sub 3]. Because DNA-RNA hybrids are important structures in antisense oligonucleotide strategies, these results may influence the design of antisense oligonucleotides with attached metal complex cleaving agents.

Kolasa, K.A.; Morrow, J.R.; Sharma, A.P. (State Univ. of New York, Buffalo, NY (United States))

1993-09-15

445

Syntheses and structural analyses of four isostructural lanthanide dimers derived from thiourea-based carboxylato ligands  

NASA Astrophysics Data System (ADS)

From the reactions of 2-(3-benzoylthioureido)ethanoic acid (H 3L) and 1,10-phenanthroline (phen) with lanthanide ions, four crystalline isostructural homodinuclear complexes [Ln 2( ?2- ?2-H 2L) 2( ?2-H 2L) 2(phen) 2(NO 3) 2] 2CH 3OH (Ln = Eu ( 1), Sm ( 2), Tb ( 3) and Dy ( 4)) have been produced. In these complexes, two neighboring lanthanide ions are connected by carboxylate groups in ?2- ?2- or ?2-bridging modes. The four complexes present similar themostabilities. Their solid-state fluorescence properties have been investigated at room temperature.

Wang, Wenyue; Guo, Mengwei; Guo, Xiaofang; Lu, Huijie; Li, Gang

2011-05-01

446

Method for extracting lanthanides and actinides from acid solutions by modification of Purex solvent  

DOEpatents

A process has been developed for the extraction of multivalent lanthanide and actinide values from acidic waste solutions, and for the separation of these values from fission product and other values, which utilizes a new series of neutral bi-functional extractants, the alkyl(phenyl)-N, N-dialkylcarbamoylmethylphosphine oxides, in combination with a phase modifier to form an extraction solution. The addition of the extractant to the Purex process extractant, tri-n-butylphosphate in normal paraffin hydrocarbon diluent, will permit the extraction of multivalent lanthanide and actinide values from 0.1 to 12.0 molar acid solutions.

Horwitz, E.P.; Kalina, D.G.

1984-05-21

447

Lanthanide impurities in wide bandgap semiconductors: A possible roadmap for spintronic devices  

NASA Astrophysics Data System (ADS)

The electronic properties of lanthanide (from Eu to Tm) impurities in wurtzite gallium nitride and zinc oxide were investigated by first principles calculations, using an all electron methodology plus a Hubbard potential correction. The results indicated that the 4f-related energy levels remain outside the bandgap in both materials, in good agreement with a recent phenomenological model, based on experimental data. Additionally, zinc oxide doped with lanthanide impurities became an n-type material, showing a coupling between the 4f-related spin polarized states and the carriers. This coupling may generate spin polarized currents, which could lead to applications in spintronic devices.

Caroena, G.; Machado, W. V. M.; Justo, J. F.; Assali, L. V. C.

2013-02-01

448

Synthesis, characterization and preliminary cytotoxicity evaluation of five lanthanide(III)-plumbagin complexes.  

PubMed

Plumbagin (5-hydroxy-2-methyl-1,4-naphthoquinone, H-PLN) was isolated from Plumbago zeylanica, the anticancer traditional Chinese medicine (TCM). Five new lanthanide(III) complexes of deprotonated plumbagin: [Y(PLN)(3)(H(2)O)(2)] (1), [La(PLN)(3)(H(2)O)(2)] (2), [Sm(PLN)(3)(H(2)O)(2)]?H(2)O (3), [Gd(PLN)(3)(H(2)O)(2)] (4), and [Dy(PLN)(3)(H(2)O)(2)] (5) were synthesized by the reaction of plumbagin with the corresponding lanthanide salts, in amounts equal to ligand/metal molar ratio of 3:1. The PLN-lanthanide(III) complexes were characterized by different physicochemical methods: elemental analyses, UV-visible, IR and (1)H NMR and ESI-MS (electrospray ionization mass spectrum) as well as TGA (thermogravimetric analysis). The plumbagin and its lanthanide(III) complexes 1-5, were tested for their in vitro cytotoxicity against BEL7404 (liver cancer) cell lines by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. The five PLN-lanthanide (III) complexes 1-5 effectively inhibited BEL7404 cell lines growth with IC(50) values of 11.0±3.5, 5.1±1.3, 6.1±1.1, 6.4±1.3, and 9.8±1.5 ?M, respectively, and exhibited a significantly enhanced cytotoxicity compared to plumbagin and the corresponding lanthanide salts, suggesting a synergistic effect upon plumbagin coordination to the Ln(III) ion. The lanthanide complexes under investigation also exerted dose- and time-dependent cytotoxic activity. [La(PLN)(3)(H(2)O)(2)] (2) and plumbagin interact with calf thymus DNA (ct-DNA) mainly via intercalation mode, but for [La(PLN)(3)(H(2)O)(2)] (2), the electrostatic interaction should not be excluded; the binding affinity of [La(PLN)(3)(H(2)O)(2)] (2) to DNA is stronger than that of free plumbagin, which may correlate with the enhanced cytotoxicity of the PLN-lanthanide(III) complexes. PMID:21421129

Chen, Zhen-Feng; Tan, Ming-Xiong; Liu, Yan-Cheng; Peng, Yan; Wang, Hong-Hong; Liu, Hua-Gang; Liang, Hong

2011-03-01

449

Synthesis of chlorin-sensitized near infrared-emitting lanthanide complexes.  

PubMed

Lanthanide (Yb(3+), Nd(3+)) complexes equipped with red-absorbing hydroporphyrin (chlorin) antennae were synthesized and characterized. The syntheses are scalable, highly modular, and enable the introduction of different chlorins functionalized with a single reactive group (COOH or NH(2)). Absorption maxima were dependent on chlorin substitution pattern (monomeso aryl or dimeso aryl) and metalation state (free base or zinc chelate). The complexes benefit from dual chlorin (610-639 nm) and lanthanide (980 or 1065 nm for Yb- or Nd-complexes, respectively) emission in the biologically relevant red and near IR region of the spectrum. PMID:22978627

Laakso, Johanna; Rosser, Geraldine A; Szíjjártó, Csongor; Beeby, Andrew; Borbas, K Eszter

2012-10-01

450

Investigating metal size effects in the Ln/As/Se/amine (Ln = lanthanide excluding Pm, amine = en, dien, en+trien) systems: solvothermal syntheses and characterizations of lanthanide selenidoarsenates.  

PubMed

Three solvothermal systems Ln/As/Se/en, Ln/As/Se/dien and Ln/As/Se/(en+trien) (Ln = lanthanide excluding Pm, en = ethylenediamine, dien = diethylenetriamine, trien = triethylenetetramine) were investigated in detail across the lanthanide series, and ternary lanthanide selenidoarsenates [Ln(en)(3)(H(2)O)(mu-eta(1),eta(1)-AsSe(4))] (Ln = La(1a), Ce(1b), Nd(1c)), [Ln(en)(4)]AsSe(4) x 0.5 en (Ln = Sm(1d), Gd(1e), Dy(1f)), [Ln(dien)(2)(mu-eta(1),eta(2)-AsSe(4))] (Ln = La(2a), Ce(2b), Pr(2c)), [Ln(en)(trien)(mu-eta(1),eta(2)-AsSe(4))] (Ln = La(3a), Nd(3b)) and [Sm(en)(trien)(eta(2)-AsSe(4))] (3c) were prepared. Systematic investigations of the three systems clarify the relationship between the molecular structures of the synthetic lanthanide selenidoarsenates and the metal size evolution of the lanthanide series. Meanwhile, the coordination modes of the [AsSe(4)](3-) tetrahedral anion to the same lanthanide ion are dependent on the denticity of ethylene polyamine as the second ligand. The lanthanide selenidoarsenates exhibit semiconducting properties with E(g) between 2.15 and 2.31 eV. PMID:20574575

Wang, Jiao; Pan, Yingli; Chen, Jiangfang; Gu, Jiansheng; Zhang, Yong; Jia, Dingxian

2010-08-14

451

Microfluidic Screening of Electrophoretic Mobility Shifts Elucidates Riboswitch Binding Function  

PubMed Central

Riboswitches are RNA sensors that change conformation upon binding small molecule metabolites, in turn modulating gene expression. Our understanding of riboswitch regulatory function would be accelerated by a high throughput, quantitative screening tool capable of measuring riboswitch-ligand binding. We introduce a microfluidic mobility shift assay that enables precise and rapid quantitation of ligand binding and subsequent riboswitch conformational change. In 0.3% of the time required for bench top assays (3.2 min vs. 1020 min), we screen and validate five candidate SAM-I riboswitches isolated from thermophilic and cryophilic bacteria. The format offers enhanced resolution of conformational change compared to slab gel formats, quantitation and repeatability for statistical assessment of small mobility shifts, low reagent consumption, and riboswitch characterization without modification of the aptamer structure. Appreciable analytical sensitivity coupled with high resolution separation performance allows quantitation of equilibrium dissociation constants (Kd) for both rapidly and slowly interconverting riboswitch-ligand pairs as validated through experiments and modeling. Conformational change, triplicate mobility shift measurements, and Kd are reported for both a known and a candidate SAM-I riboswitch with comparison to in-line probing assay results. The microfluidic mobility shift assay establishes a scalable format for the study of riboswitch-ligand binding that will advance the discovery and selection of novel riboswitches and the development of antibiotics to target bacterial riboswitches.

Karns, Kelly; Vogan, Jacob M.; Qin, Qian; Hickey, Scott F.; Wilson, Stephen C.; Hammond, Ming C.; Herr, Amy E.

2013-01-01

452

Phase shifting diffraction interferometer  

DOEpatents

An interferometer which has the capability of measuring optical elements and systems with an accuracy of {lambda}/1000 where {lambda} is the wavelength of visible light. Whereas current interferometers employ a reference surface, which inherently limits the accuracy of the measurement to about {lambda}/50, this interferometer uses an essentially perfect spherical reference wavefront generated by the fundamental process of diffraction. This interferometer is adjustable to give unity fringe visibility, which maximizes the signal-to-noise, and has the means to introduce a controlled prescribed relative phase shift between the reference wavefront and the wavefront from the optics under test, which permits analysis of the interference fringe pattern using standard phase extraction algorithms. 8 figs.

Sommargren, G.E.

1996-08-29

453

Phase shifting diffraction interferometer  

DOEpatents

An interferometer which has the capability of measuring optical elements and systems with an accuracy of .lambda./1000 where .lambda. is the wavelength of visible light. Whereas current interferometers employ a reference surface, which inherently limits the accuracy of the measurement to about .lambda./50, this interferometer uses an essentially perfect spherical reference wavefront generated by the fundamental process of diffraction. This interferometer is adjustable to give unity fringe visibility, which maximizes the signal-to-noise, and has the means to introduce a controlled prescribed relative phase shift between the reference wavefront and the wavefront from the optics under test, which permits analysis of the interference fringe pattern using standard phase extraction algorithms.

Sommargren, Gary E. (Santa Cruz, CA) [Santa Cruz, CA

1996-01-01

454

Phase shifting interferometer  

DOEpatents

An interferometer which has the capability of measuring optical elements and systems with an accuracy of .lambda./1000 where .lambda. is the wavelength of visible light. Whereas current interferometers employ a reference surface, which inherently limits the accuracy of the measurement to about .lambda./50, this interferometer uses an essentially perfect spherical reference wavefront generated by the fundamental process of diffraction. Whereas current interferometers illuminate the optic to be tested with an aberrated wavefront which also limits the accuracy of the measurement, this interferometer uses an essentially perfect spherical measurement wavefront generated by the fundamental process of diffraction. This interferometer is adjustable to give unity fringe visibility, which maximizes the signal-to-noise, and has the means to introduce a controlled prescribed relative phase shift between the reference wavefront and the wavefront from the optics under test, which permits analysis of the interference fringe pattern using standard phase extraction algorithms.

Sommargren, Gary E. (Santa Cruz, CA) [Santa Cruz, CA

1999-01-01

455

Optically transparent, superhydrophobic methyltrimethoxysilane based silica coatings without silylating reagent  

NASA Astrophysics Data System (ADS)

The superhydrophobic surfaces have drawn lot of interest, in both academic and industries because of optically transparent, adherent and self-cleaning behavior. Surface chemical composition and morphology plays an important role in determining the superhydrophobic nature of coating surface. Such concert of non-wettability can be achieved, using surface modifying reagents or co-precursor method in sol-gel process. Attempts have been made to increase the hydrophobicity and optical transparency of methyltrimethoxysilane (MTMS) based silica coatings using polymethylmethacrylate (PMMA) instead of formal routes like surface modification using silylating reagents. The optically transparent, superhydrophobic uniform coatings were obtained by simple dip coating method. The molar ratio of MTMS:MeOH:H 2O was kept constant at 1:5.63:1.58, respectively with 0.5 M NH 4F as a catalyst and the weight percent of PMMA varied from 1 to 8. The hydrophobicity of silica coatings was analyzed by FTIR and contact angle measurements. These substrates exhibited 91% optical transmittance as compared to glass and water drop contact angle as high as 171 ± 1°. The effect of humidity on hydrophobic nature of coating has been studied by exposing these films at relative humidity of 90% at constant temperature of 30 °C for a period of 45 days. The micro-structural studies carried out by transmission electron microscopy (TEM).

Kavale, Mahendra S.; Mahadik, D. B.; Parale, V. G.; Wagh, P. B.; Gupta, Satish C.; Rao, A. Venkateswara; Barshilia, Harish C.

2011-10-01

456

Surface immobilized hydrogels as versatile reagent reservoirs for microarrays.  

PubMed

The accuracy of antibody-based microarrays depends on eliminating or at least minimizing the effect of cross-reactive components. In this work, a method to create a versatile, compartmentalized storage system for antibodies and soluble microarray reagents is described. These containers are made of hydrogel plugs immobilized on a slide facing the corresponding sub-array on a printed surface. The hydrogels were polymerized using a 4% w/v N,N-dimethylacrylamide and 3% w/v bisacrylamide solution, thus generating large pore sizes to allow the facile transfer of intact, functional biomolecules. The hydrogel microenvironments can be desiccated and rehydrated with a desired solution, and they can store reagents in a dry form. These hydrogels were shown to provide limits of detection similar to those obtained by conventional incubation conditions in an assay for HIV p24 antigen. Moreover, they prevent cross-reactivity issues in the detection of Staphylococcus aureus enterotoxins A and B and promote the accurate quantification of interleukin 10 by a microarray-integrated calibration curve. PMID:23454034

Sola, Laura; Gagni, Paola; Cretich, Marina; Chiari, Marcella

2013-05-31

457

Advanced oxidation and mineralization of simazine using Fenton's reagent.  

PubMed

Removal of simazine from aqueous solution by Fenton's reagent oxidation was investigated. Box-Behnken statistical experiment design and the response surface methods were used to investigate the effects of simazine, H(2)O(2) and Fe (II) concentrations on simazine degradation and mineralization. Total organic carbon (TOC) and simazine removals were investigated at different reagent doses to determine the experimental conditions yielding the highest removal of simazine and TOC. Fe (II) concentration had more profound effect than H(2)O(2) for simazine removal while all parameters affected mineralization (TOC removal). Complete disappearance of simazine was achieved within 6 min reaction period. However, only 32% of simazine was mineralized after 15 min indicating formation of some intermediate products. The optimal H(2)O(2)/Fe (II)/simazine ratio resulting in the maximum pesticide (100%) and TOC removal (32%) was found to be 55/15/3 (mg L(-1)). The initial rate of simazine degradation was found to be first-order with respect to the initial simazine concentration. PMID:19297085

Catalkaya, Ebru Cokay; Kargi, Fikret

2009-09-15

458

The Effect of Reagents Mimicking Oxidative Stress on Fibrinogen Function  

PubMed Central

Fibrinogen is one of the plasma proteins most susceptible to oxidative modification. It has been suggested that modification of fibrinogen may cause thrombotic/bleeding complications associated with many pathophysiological states of organism. We exposed fibrinogen molecules to three different modification reagents—malondialdehyde, sodium hypochlorite, and peroxynitrite—that are presented to various degrees in different stages of oxidative stress. We studied the changes in fibrin network formation and platelet interactions with modified fibrinogens under flow conditions. The fastest modification of fibrinogen was caused by hypochlorite. Fibers from fibrinogen modified with either reagent were thinner in comparison with control fibers. We found that platelet dynamic adhesion was significantly lower on fibrinogen modified with malondialdehyde and significantly higher on fibrinogen modified either with hypochlorite or peroxynitrite reflecting different prothrombotic/antithrombotic properties of oxidatively modified fibrinogens. It seems that, in the complex reactions ongoing in living organisms at conditions of oxidation stress, hypochlorite modifies proteins (e.g., fibrinogen) faster and more preferentially than malondialdehyde. It suggests that the prothrombotic effects of prior fibrinogen modifications may outweigh the antithrombotic effect of malondialdehyde-modified fibrinogen in real living systems.

Stikarova, Jana; Kotlin, Roman; Riedel, Tomas; Suttnar, Jiri; Pimkova, Kristyna; Chrastinova, Leona; Dyr, Jan E.

2013-01-01

459

Reduction of Amine N-Oxides by Diboron Reagents  

PubMed Central

Facile reduction of alkylamino-, anilino-, and pyridyl-N-oxides can be achieved via the use of diboron reagents, predominantly bis(pinacolato)- and in some cases bis(catecholato)diboron [(pinB)2 and (catB)2, respectively]. Reductions occur upon simply mixing the amine N-oxide and the diboron reagent in a suitable solvent, at a suitable temperature. Extremely fast reductions of alkylamino- and anilino-N-oxides occur, whereas pyridyl-N-oxides undergo slower reduction. The reaction is tolerant of a variety of functionalities such as hydroxyl, thiol, and cyano groups, as well as halogens. Notably, a sensitive nucleoside N-oxide has also been reduced efficiently. The different rates with which alkylamino- and pyridyl-N-oxides are reduced has been used to perform stepwise reduction of the N,N’-dioxide of (S)-(–)-nicotine. Because it was observed that (pinB)2 was unaffected by the water of hydration in amine oxides, the feasibility of using water as solvent was evaluated. These reactions also proceeded exceptionally well, giving high product yields. In constrast to the reactions with (pinB)2, triethylborane reduced alkylamino-N-oxides, but pyridine N-oxide did not undergo efficient reduction even at elevated temperature. Finally, the mechanism of the reductive process by (pinB)2 has been probed by 1H and 11B NMR.

Kokatla, Hari Prasad; Thomson, Paul F.; Bae, Suyeal; Doddi, Venkata Ramana; Lakshman, Mahesh K.

2011-01-01

460

Radiation resistance of biological reagents for in situ life detection.  

PubMed

Life on Mars, if it exists, may share a common ancestry with life on Earth derived from meteoritic transfer of microbes between the planets. One means to test this hypothesis is to isolate, detect, and sequence nucleic acids in situ on Mars, then search for similarities to known common features of life on Earth. Such an instrument would require biological and chemical components, such as polymerase and fluorescent dye molecules. We show that reagents necessary for detection and sequencing of DNA survive several analogues of the radiation expected during a 2-year mission to Mars, including proton (H-1), heavy ion (Fe-56, O-18), and neutron bombardment. Some reagents have reduced performance or fail at higher doses. Overall, our findings suggest it is feasible to utilize space instruments with biological components, particularly for mission durations of up to several years in environments without large accumulations of charged particles, such as the surface of Mars, and have implications for the meteoritic transfer of microbes between planets. PMID:23330963

Carr, Christopher E; Rowedder, Holli; Vafadari, Cyrus; Lui, Clarissa S; Cascio, Ethan; Zuber, Maria T; Ruvkun, Gary

2013-01-01

461

Partial inactivation of cytochrome c oxidase by nonpolar mercurial reagents  

SciTech Connect

Purified beef heart cytochrome c oxidase is inactivated to the extent of 35 to 50% by the nonpolar mercurial reagents mercuric chloride and ethylmercuric chloride. The inactivation is complete within 5 min. In titrations of activity, the plateau level of inactivation is attained at added ethylmercuric chloride:heme a ratios of about 1:1. Up to 3 mercury atoms/heme a are bound to the oxidase, although only the first of these affects its enzymatic activity. Incubation of the ethylmercury-modified oxidase with sulfhydryl compounds reverses the inactivation, with 2,3-dimercaptopropanol being most effective of the reagents tested. Spectrophotometric and polarographic assays of enzymatic activity show that K/sub m/ values for the native and the ethylmercury-modified enzymes are practically indistinguishable, and that the partial inactivation observed for the latter is reflected exclusively in a lower value of V/sub max/ compared to that of the native enzyme. Based on these results, we propose that ethylmercuric chloride reacts with a single crucial--SH group per heme a, and that electron transfer processes in the modified product are partially inhibited.

Mann, A.J.; Auer, H.E.

1980-01-25

462

Hydraulically actuated well shifting tool  

SciTech Connect

This patent describes a hydraulically actuated shifting tool for actuating a sliding member in a well tool. It comprises: a housing having a hydraulic fluid bore therein; shifting dog means positioned on the housing for movement away and toward the housing; locking dog means positioned on the housing for movement away and toward the body; shifting dog hydraulic actuating means in fluid communication with the bore for causing engagement of the shifting dogs with the sliding member; locking dog hydraulic actuating means in communication with the bore for causing engagement of the locking dogs with the locking means; and hydraulic shifting means in communication with the bore for causing relative movement between the shifting dog means and the locking dog means for shifting the sliding sleeve.

Roth, B.A.

1992-10-20

463

Oxidative injury in the brain of mice caused by lanthanid.  

PubMed

The organ toxicity of lanthanides (Ln) on organisms had been recognized, but very little is known about the oxidative injury of brain caused by Ln. In order to study the mechanisms underlying the effects of Ln on the brain, ICR mice were injected with a single 20 mg/kg body weight dose of LaCl(3), CeCl(3), and NdCl(3) into the abdominal cavity daily for 14 days. We then examined the coefficient of the brain, the brain pathological changes and oxidative stress-mediated responses, and the accumulation of Ln and levels of neurochemicals in the brain. The results showed that CeCl(3) and NdCl(3) could induce some neurons to turn inflammatory cells and slight edema but did not observe the brain pathological changes from LaCl(3)-treated group. The concentrations of La, Ce, and Nd in the brain were significantly different and ranked in the order of Ce, Nd, and La. The injury of the brain and oxidative stress occurred as Ln appeared to trigger a cascade of reactions such as lipid peroxidation, the decreases of the total antioxidation capacity and activities of antioxidative enzymes, the excessive release of nitric oxide, the increase of glutamic acid, and the downregulated level of acetylcholinesterase activities. Furthermore, both Ce(3+) and Nd(3+) exhibited higher oxidative stress and toxicity on brain than La(3+), and Ce(3+) caused more severe brain injuries and oxidative stress than Nd(3+), implying that the differences in the brain injuries caused by Ln might be related to the number of 4f electrons of Ln. PMID:20614199

Zhao, Haiquan; Cheng, Zhe; Hu, Renping; Chen, Jie; Hong, Mengmeng; Zhou, Min; Gong, Xiaolan; Wang, Ling; Hong, Fashui

2011-08-01