Science.gov

Sample records for metal ion analysis

  1. Development of a lithium liquid metal ion source for MeV ion beam analysis

    SciTech Connect

    Read, P.M.; Maskrey, J.T.; Alton, G.D.

    1988-01-01

    Lithium liquid metal ion sources are an attractive complement to the existing gaseous ion sources that are extensively used for ion beam analysis. This is due in part to the high brightness of the liquid metal ion source and in part to the availability of a lithium ion beam. High brightness is of particular importance to MeV ion microprobes which are now approaching current density limitations on targets determined by the ion source. The availability of a lithium beam provides increased capabilities for hydrogen profiling and high resolution Rutherford backscattering spectrometry. This paper describes the design and performance of a lithium liquid metal ion source suitable for use on a 5MV Laddertron accelerator. Operational experience with the source and some of its uses for ion beam analysis are discussed. 8 refs., 2 figs.

  2. Towards metals analysis using corona discharge ionization ion mobility spectrometry.

    PubMed

    Jafari, Mohammad T; Saraji, Mohammad; Sherafatmand, Hossein

    2016-02-25

    For the first time, the capability of corona discharge ionization ion mobility spectrometry (CD-IMS) in the determination of metal complex was evaluated. The extreme simplicity of dispersive liquid-liquid microextraction (DLLME) coupled to the high sensitivity of CD-IMS measurement could make this combination really useful for simple, rapid, and sensitive determination of metals in different samples. In this regard, mercury, as a model metal, was complexed with diethyldithiocarbamate (DEDTC), and then extracted into the carbon tetrachloride using DLLME. Some parameters affecting the extraction efficiency, including the type and volume of the extraction solvent, the type and volume of the disperser solvent, the concentration of the chelating agent, salt addition and, pH were exhaustively investigated. Under the optimized condition, the enrichment factor was obtained to be 142. The linear range of 0.035-10.0 μg mL(-1) with r(2) = 0.997 and the detection limit of 0.010 μg mL(-1) were obtained. The relative standard deviation values were calculated to be lower than 4% and 8% for intra-day and inter-day, respectively. Finally, the developed method was successfully applied for the extraction and determination of mercury in various real samples. The satisfactory results revealed the capability of the proposed method in trace analysis without tedious derivatization or hydride generation. PMID:26851088

  3. Analysis of Supercritical-Extracted Chelated Metal Ions From Mixed Organic-Inorganic Samples

    NASA Technical Reports Server (NTRS)

    Sinha, Mahadeva P. (Inventor)

    1996-01-01

    Organic and inorganic contaminants of an environmental sample are analyzed by the same GC-MS instrument by adding an oxidizing agent to the sample to oxidize metal or metal compounds to form metal ions. The metal ions are converted to chelate complexes and the chelate complexes are extracted into a supercritical fluid such as CO2. The metal chelate extract after flowing through a restrictor tube is directly injected into the ionization chamber of a mass spectrometer, preferably containing a refractory metal filament such as rhenium to fragment the complex to release metal ions which are detected. This provides a fast, economical method for the analysis of metal contaminants in a sample and can be automated. An organic extract of the sample in conventional or supercritical fluid solvents can be detected in the same mass spectrometer, preferably after separation in a supercritical fluid chromatograph.

  4. Depth resolution improvement in secondary ion mass spectrometry analysis using metal cluster complex ion bombardment

    SciTech Connect

    Tomita, M.; Kinno, T.; Koike, M.; Tanaka, H.; Takeno, S.; Fujiwara, Y.; Kondou, K.; Teranishi, Y.; Nonaka, H.; Fujimoto, T.; Kurokawa, A.; Ichimura, S.

    2006-07-31

    Secondary ion mass spectrometry analyses were carried out using a metal cluster complex ion of Ir{sub 4}(CO){sub 7}{sup +} as a primary ion beam. Depth resolution was evaluated as a function of primary ion species, energy, and incident angle. The depth resolution obtained using cluster ion bombardment was considerably better than that obtained by oxygen ion bombardment under the same experimental condition due to reduction of atomic mixing in the depth. The authors obtained a depth resolution of {approx}1 nm under 5 keV, 45 deg. condition. Depth resolution was degraded by ion-bombardment-induced surface roughness at 5 keV with higher incident angles.

  5. A cross-reactive sensor array for the fluorescence qualitative analysis of heavy metal ions.

    PubMed

    Kang, Huaizhi; Lin, Liping; Rong, Mingcong; Chen, Xi

    2014-11-01

    A cross-reactive sensor array using mercaptopropionic acid modified cadmium telluride (CdTe), glutathione modified CdTe, poly(methacrylic acid) modified silver nanoclusters, bovine serum albumin modified gold nanoclusters, rhodamine derivative and calcein blue as fluorescent indicators has been designed for the detection of seven heavy metal ions (Ag(+), Hg(2+), Pb(2+), Cu(2+), Cr(3+), Mn(2+) and Cd(2+)). The discriminatory capacity of the sensor array to different heavy metal ions in different pH solutions has been tested and the results have been analyzed with linear discriminant analysis. Results showed that the sensor array could be used to qualitatively analyze the selected heavy metal ions. The array performance was also evaluated in the identification of known and unknown samples and the preliminary results suggested the promising practicability of the designed sensor assay. PMID:25127598

  6. Nanopore analysis of the effect of metal ions on the folding of peptides and proteins.

    PubMed

    Lee, Jeremy S

    2014-03-01

    In this minireview, the nanopore analysis of peptides and proteins in the presence of divalent metal ions will be surveyed. In all cases the binding of the metal ions causes the peptide or protein to adopt a more compact conformation which can no longer enter the α-hemolysin pore. In the absence of Zn(II) the 30-amino acid Zn-finger peptide can readily translocate the pore; but upon addition of Zn(II) the peptide folds and only bumping events are observed. Similarly, the octapeptide repeat from the N-terminus of the prion protein binds Cu(II), which prevents it from translocating. The full-length prion protein also undergoes conformational changes upon binding Cu(II), which results in an increase in the proportion of bumping events. Myelin basic protein of 170 residues is intrinsically disordered and, perhaps surprisingly, for a basic protein of this size, can translocate against the electric field based on the observation that the event time increases with increasing voltage. It, too, folds into a more compact conformation upon binding Cu(II) and Zn(II), which prevents translocation. Finally even proteins such as maltose binding protein which does not contain a formal binding site for metal ions undergoes conformational changes in the presence of the metal chelator, EDTA. Thus, contamination of proteins with trace metal ions should be considered when studying proteins and peptides by nanopore analysis. PMID:24370255

  7. Application of flowing stream techniques to water analysis Part III. Metal ions: alkaline and alkaline-earth metals, elemental and harmful transition metals, and multielemental analysis.

    PubMed

    Miró, Manuel; Estela, José Manuel; Cerdà, Víctor

    2004-05-28

    In the earlier parts of this series of reviews [1,2], the most relevant flowing stream techniques (namely, segmented flow analysis, continuous flow analysis, flow injection (FI) analysis, sequential injection (SI) analysis, multicommuted flow injection analysis and multisyringe flow injection analysis) applied to the determination of several core inorganic parameters for water quality assessment, such as nutrients and anionic species including nitrogen, sulfur and halogen compounds, were described. In the present paper, flow techniques are presented as powerful analytical tools for the environmental monitoring of metal ions (alkaline and alkaline-earth metals, and elemental and harmful transition metals) as well as to perform both multielemental and speciation analysis in water samples. The potentials of flow techniques for automated sample treatment involving on-line analyte separation and/or pre-concentration are also discussed in the body of the text, and demonstrated for each individual ion with a variety of strategies successfully applied to trace analysis. In this context, the coupling of flow methodologies with atomic spectrometric techniques such as flame atomic absorption spectrometry (FAAS), electrothermal atomic absorption spectrometry (ETAAS), inductively coupled plasma mass spectrometry (ICPMS) or hydride-generation (HG)/cold-vapor (CV) approaches, launching the so-called hyphenated techniques, is specially worth mentioning. PMID:18969420

  8. Metal Ion Sources for Ion Beam Implantation

    SciTech Connect

    Zhao, W. J.; Zhao, Z. Q.; Ren, X. T.

    2008-11-03

    In this paper a theme touched upon the progress of metal ion sources devoted to metal ion beam implantation (MIBI) will be reviewed. A special emphasis will be given to some kinds of ion sources such as ECR, MEVVA and Cluster ion sources. A novel dual hollow cathode metal ion source named DUHOCAMIS will be introduced and discussed.

  9. Formation of metal-ion adducts and evidence for surface-catalyzed ionization in electrospray analysis of pharmaceuticals and pesticides

    USGS Publications Warehouse

    Thurman, E.M.; Ferrer, I.

    2002-01-01

    The formation of metal ion adducts in liquid chromatography/mass spectrometry positive-ion electrospray analysis of pharmaceuticals and pesticides was investigated. The evidence of surface-catalyzed ionization in the electrospray analysis was also studied. Both positive and negative ion mass spectrometry were used for the analysis of the products. It was found that the sodium adducts formed in the analysis included single, double, and triple sodium adducts. Adduction was found to occur by attachment of the metal ion to carboxyl, carbonyl and aromatic pi electrons of the molecule.

  10. Metal Ions in Unusual Valency States.

    ERIC Educational Resources Information Center

    Sellers, Robin M.

    1981-01-01

    Discusses reactivity of metal ions with the primary products of water radiolysis, hyper-reduced metal ions, zero-valent metal ions, unstable divalent ions from the reduction of bivalent ions, hyper-oxidized metal ions, and metal complexes. (CS)

  11. Multicomponent analysis of mixed rare-earth metal ion solutions by the electronic tongue sensor system

    SciTech Connect

    Legin, A.; Kirsanov, D.; Rudnitskaya, A.; Rovny, S.; Logunov, M.

    2007-07-01

    Novel electrochemical sensors based on well-known extracting agents are developed. Sensors have shown high sensitivity towards a variety of rear earth metal ions in acidic media at pH=2. Multi-sensor system (electronic tongue) comprising newly developed sensors was successfully applied for the analysis of binary and ternary mixtures of Ce{sup 3+}, Nd{sup 3+}, Sm{sup 3+} and Gd{sup 3+} cations in different combinations. (authors)

  12. Analysis of the interactions between He + ions and transition metal surfaces using co-axial impact collision ion scattering spectroscopy

    NASA Astrophysics Data System (ADS)

    Walker, M.; Brown, M. G.; Draxler, M.; Fishwick, L.; Dowsett, M. G.; McConville, C. F.

    2011-01-01

    The interactions between low energy He + ions and a series of transition metal surfaces have been studied using co-axial impact collision ion scattering spectroscopy (CAICISS). Experimental data were collected from the Ni(110), Cu(100), Pd(111), Pt(111) and Au(111) surfaces using ion beams with primary energies between 1.5 keV and 4.0 keV. The shadow cone radii deduced from the experimental surface peak positions were found to closely match theoretical predictions. Data analysis was performed using both the FAN and Kalypso simulation codes, revealing a consistent requirement for a reduction of 0.252 in the screening length correction in the Molière approximation within the Thomas-Fermi (TFM) interaction potential. The adjustments of the screening length in the TFM potential, predicted by O'Connor, and the uncorrected Ziegler-Biersack-Littmark (ZBL) potential both yielded inaccurate results for all of the surfaces and incident energies studied. We also provide evidence that, despite their different computational methodologies, the FAN and Kalypso simulation codes generate similar results given identical input parameters for the analysis of 180° backscattering spectra.

  13. Multidiagnostics analysis of ion dynamics in ultrafast laser ablation of metals over a large fluence range

    SciTech Connect

    Anoop, K. K.; Polek, M. P.; Bruzzese, R.; Amoruso, S.; Harilal, Sivanandan S.

    2015-02-28

    The ions dynamics in ultrafast laser ablation of metals is studied over a fluence range spanning from the ablation threshold up to ~75 J/cm2 by means of three established diagnostic techniques. Langmuir probe, Faraday cup and spectrally resolved ICCD imaging simultaneously monitor the laser-produced plasma ions produced during ultrafast laser ablation of a copper target. The fluence dependence of ion yield is analyzed observing the occurrence of three different regimes. Moreover, the specific ion yield shows a maximum at about 4-5 J/cm2, followed by a gradual reduction and a transition to a high-fluence regime above ~50 J/cm2. The fluence variation of the copper ions angular distribution is also analyzed, observing a gradual increase of forward peaking of Cu ions for fluences up to ~10 J/cm2. Then, a broader ion component is observed at larger angles for fluences larger than ~10 J/cm2. Finally, an experimental characterization of the ions angular distribution for several metallic targets (Mg, Al, Cr, Fe, Cu, and W) is carried out at a relatively high fluence of ~66 J/cm2. Interestingly, the ion emission from the volatile metals show a narrow forward peaked distribution and a high peak ion yield compared to the refractory metals. Moreover, the width of ion angular distributions presents a striking correlation with the peak ion yield.

  14. Metal ion-containing epoxies

    NASA Technical Reports Server (NTRS)

    Stoakley, D. M.; St.clair, A. K.

    1982-01-01

    A variety of metallic and organometallic complexes to be used as potential additives for an epoxy used by the aerospace industry as a composite matrix resin were investigated. A total of 9 complexes were screened for compatibility and for their ability to accelerate or inhibit the cure of a highly crosslinkable epoxy resin. Methods for combining the metallic complexes with the resin were investigated, gel times recorded, and cure exotherms studied by differential scanning calorimetry. Glass transition temperatures of cured metal ion containing epoxy castings were determined by thermomechanical analysis. Thermal stabilities of the castings were determined by thermogravimetric analysis. Mechanical strength and stiffness of these doped epoxies were also measured.

  15. Hydrophilic polydopamine-coated graphene for metal ion immobilization as a novel immobilized metal ion affinity chromatography platform for phosphoproteome analysis.

    PubMed

    Yan, Yinghua; Zheng, Zhifang; Deng, Chunhui; Li, Yan; Zhang, Xiangmin; Yang, Pengyuan

    2013-09-17

    To discover trace phosphorylated proteins or peptides with great biological significance for in-depth phosphoproteome analysis, it is urgent to develop a novel technique for highly selective and effective enrichment of phosphopeptides. In this work, an IMAC (immobilized metal ion affinity chromatography) material with polydopamine coated on the surface of graphene and functionalized with titanium ions (denoted as Ti(4+)-G@PD) was initially designed and synthesized. The newly prepared Ti(4+)-G@PD with enhanced hydrophilicity and biological compatibility was characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and infrared (IR), and its performance for selective and effective enrichment of phosphopeptide was evaluated with both standard peptide mixtures and human serum. PMID:23941301

  16. Requirement for transient metal ions revealed through computational analysis for DNA polymerase going in reverse

    PubMed Central

    Perera, Lalith; Freudenthal, Bret D.; Beard, William A.; Shock, David D.; Pedersen, Lee G.; Wilson, Samuel H.

    2015-01-01

    DNA polymerases facilitate faithful insertion of nucleotides, a central reaction occurring during DNA replication and repair. DNA synthesis (forward reaction) is “balanced,” as dictated by the chemical equilibrium by the reverse reaction of pyrophosphorolysis. Two closely spaced divalent metal ions (catalytic and nucleotide-binding metals) provide the scaffold for these reactions. The catalytic metal lowers the pKa of O3′ of the growing primer terminus, and the nucleotide-binding metal facilitates substrate binding. Recent time-lapse crystallographic studies of DNA polymerases have identified an additional metal ion (product metal) associated with pyrophosphate formation, leading to the suggestion of its possible involvement in the reverse reaction. Here, we establish a rationale for a role of the product metal using quantum mechanical/molecular mechanical calculations of the reverse reaction in the confines of the DNA polymerase β active site. Additionally, site-directed mutagenesis identifies essential residues and metal-binding sites necessary for pyrophosphorolysis. The results indicate that the catalytic metal site must be occupied by a magnesium ion for pyrophosphorolysis to occur. Critically, the product metal site is occupied by a magnesium ion early in the pyrophosphorolysis reaction path but must be removed later. The proposed dynamic nature of the active site metal ions is consistent with crystallographic structures. The transition barrier for pyrophosphorolysis was estimated to be significantly higher than that for the forward reaction, consistent with kinetic activity measurements of the respective reactions. These observations provide a framework to understand how ions and active site changes could modulate the internal chemical equilibrium of a reaction that is central to genome stability. PMID:26351676

  17. Multidiagnostic analysis of ion dynamics in ultrafast laser ablation of metals over a large fluence range

    SciTech Connect

    Anoop, K. K. Bruzzese, R.; Amoruso, S.; Polek, M. P.; Harilal, S. S.

    2015-02-28

    The dynamics of ions in ultrafast laser ablation of metals is studied over fluences ranging from the ablation threshold up to ≈75 J/cm{sup 2} by means of three well-established diagnostic techniques. Langmuir probe, Faraday cup, and spectrally resolved intensified charge coupled device imaging simultaneously monitored the ions produced during ultrafast laser ablation of a pure copper target with 800 nm, ≈50 fs, Ti: Sapphire laser pulses. The fluence dependence of ion yield is analyzed, resulting in the observance of three different regimes. The specific ion yield shows a maximum at about 4–5 J/cm{sup 2}, followed by a gradual reduction and a transition to a high-fluence regime above ≈50 J/cm{sup 2}. The fluence dependence of the copper ions angular distribution is also analyzed, observing a gradual increase in forward-peaking of Cu ions for fluences up to ≈10 J/cm{sup 2}. A broader ion component is observed at larger angles for fluences larger than ≈10 J/cm{sup 2}. Finally, an experimental characterization of the ionic angular distribution for several metallic targets (Mg, Al, Cr, Fe, Cu, and W) is carried out at a relatively high fluence of ≈66 J/cm{sup 2}. Interestingly, the ion emission from the volatile metals shows a narrow, forward-peaked distribution, and a high peak ion yield compared to the refractory metals. Moreover, the width of ionic angular distributions presents a striking correlation with the peak ion yield.

  18. Analysis of Accumulating Ability of Heavy Metals in Lotus (Nelumbo nucifera) Improved by Ion Implantation

    NASA Astrophysics Data System (ADS)

    Zhang, Jianhua; Wang, Naiyan; Zhang, Fengshou

    2012-05-01

    Heavy metals have seriously contaminated soil and water, and done harm to public health. Academician WANG Naiyan proposed that ion-implantation technique should be exploited for environmental bioremediation by mutating and breeding plants or microbes. By implanting N+ into Taikonglian No.1, we have selected and bred two lotus cultivars, Jingguang No.1 and Jingguang No.2. The present study aims at analyzing the feasibility that irradiation can be used for remediation of soil and water from heavy metals. Compared with parent Taikonglian No.1, the uptaking and accumulating ability of heavy metals in two mutated cultivars was obviously improved. So ion implantation technique can indeed be used in bioremediation of heavy metals in soil and water, but it is hard to select and breed a cultivar which can remedy the soil and water from all the heavy metals.

  19. FTIR spectroscopy structural analysis of the interaction between Lactobacillus kefir S-layers and metal ions

    NASA Astrophysics Data System (ADS)

    Gerbino, E.; Mobili, P.; Tymczyszyn, E.; Fausto, R.; Gómez-Zavaglia, A.

    2011-02-01

    FTIR spectroscopy was used to structurally characterize the interaction of S-layer proteins extracted from two strains of Lactobacillus kefir (the aggregating CIDCA 8348 and the non-aggregating JCM 5818) with metal ions (Cd +2, Zn +2, Pb +2 and Ni +2). The infrared spectra indicate that the metal/protein interaction occurs mainly through the carboxylate groups of the side chains of Asp and Glut residues, with some contribution of the NH groups belonging to the peptide backbone. The frequency separation between the νCOO - anti-symmetric and symmetric stretching vibrations in the spectra of the S-layers in presence of the metal ions was found to be ca. 190 cm -1 for S-layer CIDCA 8348 and ca. 170 cm -1 for JCM 5818, denoting an unidentate coordination in both cases. Changes in the secondary structures of the S-layers induced by the interaction with the metal ions were also noticed: a general trend to increase the amount of β-sheet structures and to reduce the amount of α-helices was observed. These changes allow the proteins to adjust their structure to the presence of the metal ions at minimum energy expense, and accordingly, these adjustments were found to be more important for the bigger ions.

  20. Photoelectrochemical detection of metal ions.

    PubMed

    Zhao, Wei-Wei; Xu, Jing-Juan; Chen, Hong-Yuan

    2016-07-21

    Depending on the situation, metal ions may either play beneficial roles or be harmful to human health and ecosystems. Sensitive and accurate detection of metal ions is thus a critical issue in the field of analytical sciences and great efforts have been devoted to the development of various metal ion sensors. Photoelectrochemical (PEC) detection is an emerging technique for the bio/chemical detection of metal ions, and features a fast response, low cost and high sensitivity. Using representative examples, this review will first introduce the fundamentals and summarize recent progress in the PEC detection of metal ions. In addition, interesting strategies for the design of particular PEC metal ion sensors are discussed. Challenges and opportunities in this field are also presented. PMID:27297834

  1. Metal Ion Analysis Using Near-Infrared Dyes and the Laboratory-on-a-Chip

    SciTech Connect

    Collins, Greg E.

    2004-06-23

    The primary research objective of this effort is to develop a portable, capillary electrophoresis (CE) microchip capable of sensitively and rapidly monitoring hazardous waste metal ions critical to the successful deactivation and decommissioning (D&D) of contaminated equipment and structures at various DOE sites. Hazardous waste metal ions to be adapted for sensing on the microchip include UO2 2+, Be2+, Cr6+, Hg2+, Pb2+, Co2+, Ni2+, Cs+, and Sr2+. Particular emphasis will be placed on developing viable, new extraction methods for metal ion sampling from both the air via a microimpinger which is integrated onto the microchip itself, and from contaminated surfaces, both techniques being amenable to on-line introduction onto the microchip. Two different detection methods for monitoring the electrophoretic separations taking place down the microchannel will be exploited in this research, indirect and direct detection. Special emphasis will be placed on maintaining the ultimate portability of the final microchip device through the careful selection of metallochromic dyes and fluorophores which are amenable to use of small, inexpensive light sources (e.g., LED's) and photodetectors.

  2. Prevalence of Pseudotumor in Patients After Metal-On-Metal Hip Arthroplasty Evaluated with Metal Ion Analysis and MARS-MRI.

    PubMed

    Sutphen, Sean A; MacLaughlin, Lewis H; Madsen, Adam A; Russell, Jackie H; McShane, Michael A

    2016-01-01

    The purpose of this study is to quantify the prevalence of pseudotumors in patients with well-functioning and painful metal-on-metal total hip arthroplasty, to characterize the pseudotumor with the use of MARS-MRI, and to assess the relationship between pseudotumors and metal ions. We retrospectively reviewed 102 single surgeon patients. The results showed that 68.6% developed pseudotumor with 60.9% of the asymptomatic group developing pseudotumor. The symptomatic group had a higher proportion of patients with elevated serum cobalt levels (P=0.035). There was no difference found with elevated metal ions and prevalence of pseudotumor, but elevated cobalt levels were associated with larger pseudotumor size (P=0.001). The available evidence indicated that most patients that develop pseudotumors are asymptomatic, and that elevated serum cobalt levels may be associated with symptoms and pseudotumor size. PMID:26253484

  3. First order Raman scattering analysis of transition metal ions implanted GaN

    NASA Astrophysics Data System (ADS)

    Majid, Abdul; Rana, Usman Ali; Shakoor, Abdul; Ahmad, Naeem; Hassan, Najam al; Khan, Salah Ud-Din

    2016-03-01

    Transition Metal (TM) ions V, Cr, Mn and Co were implanted into GaN/sapphire films at fluences 5×1014, 5×1015 and 5×1016 cm-2. First order Raman Scattering (RS) measurements were carried out to study the effects of ion implantation on the microstructure of the materials, which revealed the appearance of disorder and new phonon modes in the lattice. The variations in characteristic modes 1GaN i.e. E2(high) and A1(LO), observed for different implanted samples is discussed in detail. The intensity of nitrogen vacancy related vibrational modes appearing at 363 and 665 cm-1 was observed for samples having different fluences. A gallium vacancy related mode observed at 277/281 cm-1 for TM ions implanted at 5×1014 cm-2 disappeared for all samples implanted with rest of fluences. The fluence dependent production of implantation induced disorder and substitution of TM ions on cationic sites is discussed, which is expected to provide necessary information for the potential use of these materials as diluted magnetic semiconductors in future spintronic devices.

  4. Consequences of Decontamination Procedures in Forensic Hair Analysis Using Metal-Assisted Secondary Ion Mass Spectrometry Analysis.

    PubMed

    Cuypers, Eva; Flinders, Bryn; Boone, Carolien M; Bosman, Ingrid J; Lusthof, Klaas J; Van Asten, Arian C; Tytgat, Jan; Heeren, Ron M A

    2016-03-15

    Today, hair testing is considered to be the standard method for the detection of chronic drug abuse. Nevertheless, the differentiation between systemic exposure and external contamination remains a major challenge in the forensic interpretation of hair analysis. Nowadays, it is still impossible to directly show the difference between external contamination and use-related incorporation. Although the effects of washing procedures on the distribution of (incorporated) drugs in hair remain unknown, these decontamination procedures prior to hair analysis are considered to be indispensable in order to exclude external contamination. However, insights into the effect of decontamination protocols on levels and distribution of drugs incorporated in hair are essential to draw the correct forensic conclusions from hair analysis; we studied the consequences of these procedures on the spatial distribution of cocaine in hair using imaging mass spectrometry. Additionally, using metal-assisted secondary ion mass spectrometry, we are the first to directly show the difference between cocaine-contaminated and user hair without any prior washing procedure. PMID:26878081

  5. Immobilized metal ion affinity chromatography.

    PubMed

    Yip, T T; Hutchens, T W

    1992-01-01

    Immobilized metal ion affinity chromatography (IMAC) (1,2) is also referred to as metal chelate chromatography, metal ion interaction chromatography, and ligand-exchange chromatography. We view this affinity separation technique as an intermediate between highly specific, high-affinity bioaffinity separation methods, and wider spectrum, low-specificity adsorption methods, such as ion exchange. The IMAC stationary phases are designed to chelate certain metal ions that have selectivity for specific groups (e.g., His residues) in peptides (e.g., 3-7) and on protein surfaces (8-13). The number of stationary phases that can be synthesized for efficient chelation of metal ions is unlimited, but the critical consideration is that there must be enough exposure of the metal ion to interact with the proteins, preferably in a biospecific manner. Several examples are presented in Fig. 1. The challenge to produce new immobilized chelating groups, including protein surface metal-binding domains (14,15) is being explored continuously. Table 1 presents a list of published procedures for the synthesis and use of stationary phases with immobilized chelating groups. This is by no means exhaustive, and is intended only to give an idea of the scope and versatility of IMAC. Fig. 1 Schematic illustration of several types of immobilized metal-chelating groups, including, iminodiacetate (IDA), tris(carboxymethyl) ethylenediamine (TED), and the metal-binding peptides (GHHPH)(n)G (where n = 1,2,3, and 5) (14,15). Table 1 Immobilized Chelating Groups and Metal Ions Used for Immobilized Metal Ion Affinity Chromatography Chelating group Suitable metal ions Reference Commercial source Immodiacetate Transitional1,2 Pharmacia LKB Pierce Sigma Boehringer Mannheim TosoHaas 2-Hydroxy-3[N-(2- pyrtdylmethyl) glycme]propyl Transitional3 Not available ?-Alky1 mtrilo triacetic acid Transitional4 Not available Carboxymethylated asparhc acid Ca(II)13 Not available Tris (carboxy- methyl) ethylene Diamme

  6. Analysis of metal ions in crude oil by reversed-phase high performance liquid chromatography using short column.

    PubMed

    Salar Amoli, H; Porgam, A; Bashiri Sadr, Z; Mohanazadeh, F

    2006-06-16

    In this study a rapid, simultaneous analysis of V, Ni, Fe and Cu in crude oil was achieved by high performance liquid chromatography using 10 cm length reversed-phase C18 column. Since the amount of metal ions is at a very low level, in this work, solvent extraction of metals by a ligand such as 8-hydroxyquinoline from acidic media was investigated with some modification to previous procedures. Average extraction recoveries were 99, 85, 94 and 96 for V, Ni, Fe and Cu, respectively. The proposed method was successfully applied to the crude oil which was obtained from Koshk area in southern Iran. Fast analysis of metal ion in reversed-phase short column was achieved with methanol/water (55/45, v/v) and the detection limits measured as three times the background noise were obtained. Also it was shown that if small amount of 8-hydroxyquinoline was added to the mobile phase, the peak height and the peak symmetry were improved. A typical chromatogram for the separation of the 8-hydroxyquinoline complexes of V (V), Ni (II), Fe (III) and Cu (II) in crude oil was obtained in less than 4 min. PMID:16723133

  7. Asparagus cochinchinensis Extract Alleviates Metal Ion-Induced Gut Injury in Drosophila: An In Silico Analysis of Potential Active Constituents

    PubMed Central

    Zhang, Weiyu; Jin, Li Hua

    2016-01-01

    Metal ions and sulfate are components of atmospheric pollutants that have diverse ways of entering the human body. We used Drosophila as a model to investigate the effect of Asparagus cochinchinensis (A. cochinchinensis) extracts on the gut and characterized gut homeostasis following the ingestion of metal ions (copper, zinc, and aluminum). In this study, we found that the aqueous A. cochinchinensis extract increased the survival rate, decreased epithelial cell death, and attenuated metal ion-induced gut morphological changes in flies following chronic exposure to metal ions. In addition, we screened out, by network pharmacology, six natural products (NPs) that could serve as putative active components of A. cochinchinensis that prevented gut injury. Altogether, the results of our study provide evidence that A. cochinchinensis might be an effective phytomedicine for the treatment of metal ion-induced gut injury. PMID:27123034

  8. Asparagus cochinchinensis Extract Alleviates Metal Ion-Induced Gut Injury in Drosophila: An In Silico Analysis of Potential Active Constituents.

    PubMed

    Zhang, Weiyu; Jin, Li Hua

    2016-01-01

    Metal ions and sulfate are components of atmospheric pollutants that have diverse ways of entering the human body. We used Drosophila as a model to investigate the effect of Asparagus cochinchinensis (A. cochinchinensis) extracts on the gut and characterized gut homeostasis following the ingestion of metal ions (copper, zinc, and aluminum). In this study, we found that the aqueous A. cochinchinensis extract increased the survival rate, decreased epithelial cell death, and attenuated metal ion-induced gut morphological changes in flies following chronic exposure to metal ions. In addition, we screened out, by network pharmacology, six natural products (NPs) that could serve as putative active components of A. cochinchinensis that prevented gut injury. Altogether, the results of our study provide evidence that A. cochinchinensis might be an effective phytomedicine for the treatment of metal ion-induced gut injury. PMID:27123034

  9. Ion beam modification of metals

    NASA Astrophysics Data System (ADS)

    Dearnaley, G.

    1990-04-01

    Energetic ions beams may be used in various ways to modify and so improve the tribological properties of metals. These methods include: — ion implantation of selected additive species; — ion beam mixing of thin deposited coatings; — ion-beam-assisted deposition of thicker overlay coatings. The first of these techniques has been widely used to modify the electronic properties of semiconductors, but has since been extended for the treatment of all classes of material. Tool steels can be strengthened by the ion implantation of nitrogen or titanium, to produce fine dispersions of hard second-phase precipitates. Solid solution strengthening, by combinations of substitutional and interstitial species, such as yttrium and nitrogen, has also been successful. Both ion beam mixing (IBM) and ion-beam-assisted deposition (IBAD) use a combination of coating and ion bombardment. In the first case, the objective is to intermix the coating and substrate by the aid of radiation-enhanced diffusion. In the latter case, the coating is densified and modified during deposition and the process can be continued in order to build up overlay coatings several μm in thickness. The surface can then be tailored, for instance to provide a hard and adherent ceramic such as silicon nitride, boron nitride or titanium nitride. It is an advantage that all the above processes can be applied at relatively low temperatures, below about 200° C, thereby avoiding distortion of precision components. Ion implantation is also being successfully applied for the reduction of corrosion, especially at high temperatures or in the atmosphere and to explore the mechanisms of oxidation. Ion-assisted coatings, being compact and adherent, provide a more substantial protection against corrosion: silicon nitride and boron nitride are potentially useful in this respect. Examples will be given of the successful application of these methods for the surface modification of metals and alloys, and developments in the

  10. PROGRESS REPORT. METAL ION ANALYSIS USING NEAR-INFRARED DYES AND THE "LABORATORY-ON-A-CHIP"

    EPA Science Inventory

    The primary research objective of this effort is to develop a portable, capillary electrophoresis microchip capable of sensitively and rapidly monitoring hazardous waste metal ions critical to the successful deactivation and decommissioning (D&D) of contaminated equipment and str...

  11. Mutational analysis of human DNase I at the DNA binding interface: implications for DNA recognition, catalysis, and metal ion dependence.

    PubMed

    Pan, C Q; Ulmer, J S; Herzka, A; Lazarus, R A

    1998-03-01

    Human deoxyribonuclease I (DNase I), an enzyme used to treat cystic fibrosis patients, has been systematically analyzed by site-directed mutagenesis of residues at the DNA binding interface. Crystal structures of bovine DNase I complexed with two different oligonucleotides have implicated the participation of over 20 amino acids in catalysis or DNA recognition. These residues have been classified into four groups based on the characterization of over 80 human DNase I variants. Mutations at any of the four catalytic amino acids His 134, His 252, Glu 78, and Asp 212 drastically reduced the hydrolytic activity of DNase I. Replacing the three putative divalent metal ion-coordinating residues Glu 39, Asp 168, or Asp 251 led to inactive variants. Amino acids Gln 9, Arg 41, Tyr 76, Arg 111, Asn 170, Tyr 175, and Tyr 211 were also critical for activity, presumably because of their close proximity to the active site, while more peripheral DNA interactions stemming from 13 other positions were of minimal significance. The relative importance of these 27 positions is consistent with evolutionary relationships among DNase I across different species, DNase I-like proteins, and bacterial sphingomyelinases, suggesting a fingerprint for a family of DNase I-like proteins. Furthermore, we found no evidence for a second active site that had been previously implicated in Mn2+-dependent DNA degradation. Finally, we correlated our mutational analysis of human DNase I to that of bovine DNase I with respect to their specific activity and dependence on divalent metal ions. PMID:9541395

  12. Mechanistic Enzyme Models: Pyridoxal and Metal Ions.

    ERIC Educational Resources Information Center

    Hamilton, S. E.; And Others

    1984-01-01

    Background information, procedures, and results are presented for experiments on the pyridoxal/metal ion model system. These experiments illustrate catalysis through Schiff's base formation between aldehydes/ketones and primary amines, catalysis by metal ions, and the predictable manner in which metal ions inhibit or catalyze reactions. (JN)

  13. Reversible photodeposition and dissolution of metal ions

    DOEpatents

    Foster, Nancy S.; Koval, Carl A.; Noble, Richard D.

    1994-01-01

    A cyclic photocatalytic process for treating waste water containing metal and organic contaminants. In one embodiment of the method, metal ions are photoreduced onto the photocatalyst and the metal concentrated by resolubilization in a smaller volume. In another embodiment of the method, contaminant organics are first oxidized, then metal ions removed by photoreductive deposition. The present invention allows the photocatalyst to be recycled until nearly complete removal of metal ions and organic contaminants is achieved.

  14. Metallic ions in the equatorial ionosphere

    NASA Technical Reports Server (NTRS)

    Aikin, A. C.; Goldberg, R. A.

    1972-01-01

    Four positive ion composition measurements of the equatorial E region made at Thumba, India, are presented. During the day, the major ions between 90 and 125 km are NO(+) and O2(+). A metallic ion layer centered at 92 km is observed, and found to contain Mg(+), Fe(+), Ca(+), K(+), Al(+), and Na(+) ions. The layer is explained in terms of a similarly shaped latitude distribution of neutral atoms which are photoionized and charge-exchanged with NO(+) and O2(+). Three body reactions form molecular metallic ions which are rapidly lost by dissociative ion-electron recombination. Nighttime observations show downward drifting of the metallic ion layer caused by equatorial dynamo effects. These ions react and form neutral metals which exchange charges with NO(+) and O2(+) to produce an observed depletion of those ions within the metallic ion region.

  15. Modified electrodes used for electrochemical detection of metal ions in environmental analysis.

    PubMed

    March, Gregory; Nguyen, Tuan Dung; Piro, Benoit

    2015-06-01

    Heavy metal pollution is one of the most serious environmental problems, and regulations are becoming stricter. Many efforts have been made to develop sensors for monitoring heavy metals in the environment. This review aims at presenting the different label-free strategies used to develop electrochemical sensors for the detection of heavy metals such as lead, cadmium, mercury, arsenic etc. The first part of this review will be dedicated to stripping voltammetry techniques, on unmodified electrodes (mercury, bismuth or noble metals in the bulk form), or electrodes modified at their surface by nanoparticles, nanostructures (CNT, graphene) or other innovative materials such as boron-doped diamond. The second part will be dedicated to chemically modified electrodes especially those with conducting polymers. The last part of this review will focus on bio-modified electrodes. Special attention will be paid to strategies using biomolecules (DNA, peptide or proteins), enzymes or whole cells. PMID:25938789

  16. Modified Electrodes Used for Electrochemical Detection of Metal Ions in Environmental Analysis

    PubMed Central

    March, Gregory; Nguyen, Tuan Dung; Piro, Benoit

    2015-01-01

    Heavy metal pollution is one of the most serious environmental problems, and regulations are becoming stricter. Many efforts have been made to develop sensors for monitoring heavy metals in the environment. This review aims at presenting the different label-free strategies used to develop electrochemical sensors for the detection of heavy metals such as lead, cadmium, mercury, arsenic etc. The first part of this review will be dedicated to stripping voltammetry techniques, on unmodified electrodes (mercury, bismuth or noble metals in the bulk form), or electrodes modified at their surface by nanoparticles, nanostructures (CNT, graphene) or other innovative materials such as boron-doped diamond. The second part will be dedicated to chemically modified electrodes especially those with conducting polymers. The last part of this review will focus on bio-modified electrodes. Special attention will be paid to strategies using biomolecules (DNA, peptide or proteins), enzymes or whole cells. PMID:25938789

  17. Incorporation of metal ions into polyimides

    NASA Technical Reports Server (NTRS)

    Taylor, L. T.; Carver, V. C.; Furtsch, T. A.; Saint Clair, A. K.

    1980-01-01

    The effects of the incorporation of metal ions into various polyimides on polyimide properties are investigated. Polyimide films derived from 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride (BDTA) 3,3'-diaminobenzophenone (m,m'-DABP), 4,4'-diaminobenzophenone (p,p'-DABP) or 4,4'-oxydianiline were prepared with the concurrent addition of approximately 20 metals in a variety of forms. In general, it is found that the films derived from BDTA + p,p'-DABP were brittle and of poor quality, with brittle films also produced in most of the BDTA + m, m'-DABP polyimides regardless of whether the added metal was hydrate or anhydrous. Thermomechanical analysis, torsional braid analysis, thermal gravimetric analysis, infrared spectral analysis and isothermal studies on many of the polyimide films produced indicate that the softening temperature is generally increased upon the addition of metal ions, at the expense of thermal stability, while no changes in chemical functionality are observed. The best system studied in regard to polymer property enhancement appears to be tri(acetylacetonato)aluminum(III) added to the m, m'-DABP polyamide, which has been found to exhibit four times the lap shear strength of the polyimide alone.

  18. Ion Mobility Spectrometry of Heavy Metals.

    PubMed

    Ilbeigi, Vahideh; Valadbeigi, Younes; Tabrizchi, Mahmoud

    2016-07-19

    A simple, fast, and inexpensive method was developed for detecting heavy metals via the ion mobility spectrometry (IMS) in the negative mode. In this method, Cl(-) ion produced by the thermal ionization of NaCl is employed as the dopant or the ionizing reagent to ionize heavy metals. In practice, a solution of mixed heavy metals and NaCl salts was directly deposited on a Nichrome filament and electrically heated to vaporize the salts. This produced the IMS spectra of several heavy-metal salts, including CdCl2, ZnSO4, NiCl2, HgSO4, HgCl2, PbI2, and Pb(Ac)2. For each heavy metal (M), one or two major peaks were observed, which were attributed to M·Cl(-) or [M·NaCl]Cl(-)complexes. The method proved to be useful for the analysis of mixed heavy metals. The absolute detection limits measured for ZnSO4 and HgSO4 were 0.1 and 0.05 μg, respectively. PMID:27321408

  19. Protein-Transition Metal Ion Networks

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Proteins obtained from agricultural sources were blended with divalent metal ions. Feather keratin, egg albumin, and wheat gluten showed increases of 2-3 times in modulus with addition of divalent transition metal ions Cu2+ and Zn2+. Increasing concentrations of ions resulted in increased stiffnes...

  20. Metal ions, Alzheimer's disease and chelation therapy.

    PubMed

    Budimir, Ana

    2011-03-01

    In the last few years, various studies have been providing evidence that metal ions are critically involved in the pathogenesis of major neurological diseases (Alzheimer, Parkinson). Metal ion chelators have been suggested as potential therapies for diseases involving metal ion imbalance. Neurodegeneration is an excellent target for exploiting the metal chelator approach to therapeutics. In contrast to the direct chelation approach in metal ion overload disorders, in neurodegeneration the goal seems to be a better and subtle modulation of metal ion homeostasis, aimed at restoring ionic balance. Thus, moderate chelators able to coordinate deleterious metals without disturbing metal homeostasis are needed. To date, several chelating agents have been investigated for their potential to treat neurodegeneration, and a series of 8-hydroxyquinoline analogues showed the greatest potential for the treatment of neurodegenerative diseases. PMID:21406339

  1. METAL ION ANALYSIS USING NEAR-INFRARED DYES AND THE "LABORATORY-ON-A-CHIP"

    EPA Science Inventory

    This project addresses the need for developing a new class of radionuclide and heavy metal complexation agents that are tagged with near-infrared dyes and, therefore, can be extended to the implementation of a compact and portable "laboratory-on-a-chip" operable in the stringent ...

  2. METAL ION ANALYSIS USING NEAR-INFRARED DYES AND THE ''LABORATORY-ON-A-CHIP''

    SciTech Connect

    Collins, Greg E.

    2001-09-15

    The DOE currently has the daunting task of deactivating 7,000 contaminated buildings and decommissioning 900 contaminated buildings that remain from the United States' involvement in nuclear weapons development over the last 50 years.1 In addition to decontaminating the metal and concrete building materials that comprise these building structures, this program will require the decontamination and disposal of more than 180,000 metric tons of scrap metal.1 The DOE is also currently entrenched in a massive cleanup program of their nuclear weapons facilities in an effort to prevent serious environmental problems arising from the already widespread contamination of soils, sediments and groundwaters. Incredibly, more than 600 billion gallons of water and 50 million cubic meters of soil have been contaminated by more than 5700 known DOE groundwater plumes.2 The primary concern is migration of these plumes and their potential threat to local and regional water sources. Sites of particular concern include the Snake River Aquifer in Idaho, contaminated groundwaters at the 100, 200 and 300 areas at Hanford, Washington, Oak Ridge/Savannah River groundwaters and contaminated sediments at the Nevada Test Site.2 Numerous landfills also exist at DOE facilities which are estimated to contain over three million cubic meters of radioactive and hazardous buried water.2 The challenges associated with these tasks are numerous, and have been outlined in various research needs statements associated with facility Decontamination and Decommissioning (D&D). The Environmental Management team has highlighted the need for revolutionizing technologies capable of improving characterization, monitoring and certification of contaminated equipment and facilities with emphasis on real time characterization in the field. One of the specific science research challenges critical to the advancement of decontamination and decommissioning (D&D) is the application of new principles and innovations to

  3. Ohmic model for electrodeposition of metallic ions

    NASA Astrophysics Data System (ADS)

    Gliozzi, A. S.; Alexe-Ionescu, A. L.; Barbero, G.

    2015-10-01

    An ohmic model to describe the electrodeposition of metallic ions on the electrodes is proposed. We assume that the ionic distribution is homogeneous across the electrolytic cell, and that the ionic current is due to the bulk electric field. The nucleation in the electrodeposition is supposed to be well described by a kinetic equation at the electrode, taking into account the neutralization of metallic ions on the electrodes. Two cases are considered. In the first case the characteristic time describing the neutralization of the ions is supposed to be negligible with respect to the flight time of the ions across the cell. In this framework the bulk electric field coincides with the external electric field, and our analysis gives analytical formulae for the surface density of deposited ions and for the electric current in the external circuit. The case where the two characteristic times are comparable, and the effective electric field in the bulk depends on the surface deposition, is considered too. In this case the ordinary differential equations describing the ionic distribution and the adsorption phenomenon have to be solved numerically. The agreement between the presented model and the experimental results published by several groups is reasonably good.

  4. Metal Ion Analysis Using Near-Infrared Dyes and the ''Laboratory-on-a-Chip''

    SciTech Connect

    Collins, Greg E.; Lu, Qin, Evans III, Lawrence

    1999-06-01

    This project addresses the need for developing a highly sensitive and selective, portable radionuclide analyzer which would permit a low-cost and timely characterization of DOE remediation sites. Through the application of near-infrared fluorophore tagged macrocycles, in combination with the capillary electrophoretic separation of radionuclide and heavy metal complexes on a microchip, we propose an innovative, low cost characterization approach to gaining timely characterization data in the field. The research goals for this program are summarized as follows: (a) To synthesize a new class of near-infrared tagged macrocycles that will take advantage of the inherent metal complexation properties of the macrocycle, while fluorescing in a region of the spectrum with very little background fluorescence. (b) To characterize the fluorescence and complexation behavior of this new class of complexation agents. (c) To implement these new materials into the design of a portable monitor for radionuclide and heavy metal analytes that utilizes the ''laboratory-on-a-chip'' technology for performing capillary electrophoresis on a microchip.

  5. Liquid metal ion source and alloy

    DOEpatents

    Clark, Jr., William M.; Utlaut, Mark W.; Behrens, Robert G.; Szklarz, Eugene G.; Storms, Edmund K.; Santandrea, Robert P.; Swanson, Lynwood W.

    1988-10-04

    A liquid metal ion source and alloy, wherein the species to be emitted from the ion source is contained in a congruently vaporizing alloy. In one embodiment, the liquid metal ion source acts as a source of arsenic, and in a source alloy the arsenic is combined with palladium, preferably in a liquid alloy having a range of compositions from about 24 to about 33 atomic percent arsenic. Such an alloy may be readily prepared by a combustion synthesis technique. Liquid metal ion sources thus prepared produce arsenic ions for implantation, have long lifetimes, and are highly stable in operation.

  6. Potentiometric titration of metal ions in ethanol.

    PubMed

    Gibson, Graham T T; Mohamed, Mark F; Neverov, Alexei A; Brown, R S

    2006-09-18

    The potentiometric titrations of Zn2+, Cu2+ and 12 Ln3+ metal ions were obtained in ethanol to determine the titration constants (defined as the at which the [-OEt]/[Mx+]t ratios are 0.5, 1.5, and 2.5) and in two cases (La3+ and Zn2+) a complete speciation diagram. Several simple monobasic acids and aminium ions were also titrated to test the validity of experimental titration measurements and to establish new constants in this medium that will be useful for the preparation of buffers and standard solutions. The dependence of the titration constants on the concentration and type of metal ion and specific counterion effects is discussed. In selected cases, the titration profiles were analyzed using a commercially available fitting program to obtain information about the species present in solution, including La3+ for which a dimer model is proposed. The fitting provides the microscopic values for deprotonation of one to four metal-bound ethanol molecules. Kinetics for the La3+-catalyzed ethanolysis of paraoxon as a function of are presented and analyzed in terms of La3+ speciation as determined by the analysis of potentiometric titration curves. The stability constants for the formation of Zn2+ and Cu2+ complexes with 1,5,9-triazacyclododecane as determined by potentiometric titration are presented. PMID:16961382

  7. Versatile high current metal ion implantation facility

    SciTech Connect

    Brown, I.G.; Dickinson, M.R.; Galvin, J.E.; Godechot, X.; MacGill, R.A.

    1991-06-01

    A metal ion implantation facility has been developed with which high current beams of practically all the solid metals of the periodic table can be produced. A multi-cathode, broad beam, metal vapor vacuum arc ion source is used to produce repetitively pulsed metal ion beams at an extraction voltage of up to 100 kV, corresponding to an ion energy of up to several hundred keV because of the ion-charge state multiplicity, and with a beam current of up to several amperes peak pulsed and several tens of mA time averaged delivered onto a downstream target. Implantation is done in a broad-beam mode, with a direct line-of-sight from ion source to target. Here we summarize some of the features of the ion source and the implantation facility that has been built up around it. 28 refs., 5 figs.

  8. Substrate Profile and Metal-ion Selectivity of Human Divalent Metal-ion Transporter-1*

    PubMed Central

    Illing, Anthony C.; Shawki, Ali; Cunningham, Christopher L.; Mackenzie, Bryan

    2012-01-01

    Divalent metal-ion transporter-1 (DMT1) is a H+-coupled metal-ion transporter that plays essential roles in iron homeostasis. DMT1 exhibits reactivity (based on evoked currents) with a broad range of metal ions; however, direct measurement of transport is lacking for many of its potential substrates. We performed a comprehensive substrate-profile analysis for human DMT1 expressed in RNA-injected Xenopus oocytes by using radiotracer assays and the continuous measurement of transport by fluorescence with the metal-sensitive PhenGreen SK fluorophore. We provide validation for the use of PhenGreen SK fluorescence quenching as a reporter of cellular metal-ion uptake. We determined metal-ion selectivity under fixed conditions using the voltage clamp. Radiotracer and continuous measurement of transport by fluorescence assays revealed that DMT1 mediates the transport of several metal ions that were ranked in selectivity by using the ratio Imax/K0.5 (determined from evoked currents at −70 mV): Cd2+ > Fe2+ > Co2+, Mn2+ ≫ Zn2+, Ni2+, VO2+. DMT1 expression did not stimulate the transport of Cr2+, Cr3+, Cu+, Cu2+, Fe3+, Ga3+, Hg2+, or VO+. 55Fe2+ transport was competitively inhibited by Co2+ and Mn2+. Zn2+ only weakly inhibited 55Fe2+ transport. Our data reveal that DMT1 selects Fe2+ over its other physiological substrates and provides a basis for predicting the contribution of DMT1 to intestinal, nasal, and pulmonary absorption of metal ions and their cellular uptake in other tissues. Whereas DMT1 is a likely route of entry for the toxic heavy metal cadmium, and may serve the metabolism of cobalt, manganese, and vanadium, we predict that DMT1 should contribute little if at all to the absorption or uptake of zinc. The conclusion in previous reports that copper is a substrate of DMT1 is not supported. PMID:22736759

  9. COMPUTATIONAL DESIGN OF METAL ION SEQUESTERING AGENTS

    EPA Science Inventory

    Organic ligands that exhibit a high degree of metal ion recognition are essential precursors for developing separation processes and sensors for metal ions. Since the beginning of the nuclear era, much research has focused on discovering ligands that target specific radionuclides...

  10. Trace analysis of heavy metals in groundwater samples by ion chromatography with post-column reaction and ultraviolet-visible detection.

    PubMed

    Santoyo, E; Santoyo-Gutiérrez, S; Verma, S P

    2000-07-01

    Groundwaters originating from local and regional aquifers surrounding ash deposits produced by a coal-fired power plant were collected. These water samples were chemically analyzed for quantifying their heavy metal composition at trace levels. A highly sensitive analytical technique based on ion chromatography with a UV-Vis detector and under isocratic eluent flow-rate conditions was used. In order to quantify the major heavy metals (Pb, Cu, Cd, Co, Zn and Ni), three ionic separation column systems were evaluated: (1) a cationic column (HPIC-CS2, Dionex) tested with two eluents (10 mM oxalic acid-7.5 mM citric acid; and 40 mM D-tartaric acid-12 mM citric acid); (2) an anionic column (HPIC-AS4, Dionex) evaluated with 25 mM oxalic acid as eluent: and (3) a bifunctional ion-exchange column (Ionpac CS5, Dionex) which was also tested with two eluents (6 mM pyridine, 2,6-dicarboxylic acid; and 50 mM oxalic acid/95 mM lithium hydroxide). The lowest detection limits achieved with the Ionpac CS5 column and the 50 mM oxalic acid-95 mM lithium hydroxide eluent enabled the heavy metal analysis in groundwater samples to be reliably performed. Details of this comparative study, including the ion chromatography procedure selected and its application to heavy metal analysis of groundwater samples, are presented in this work. PMID:10917442

  11. Pseudo ribbon metal ion beam source

    SciTech Connect

    Stepanov, Igor B. Ryabchikov, Alexander I.; Sivin, Denis O.; Verigin, Dan A.

    2014-02-15

    The paper describes high broad metal ion source based on dc macroparticle filtered vacuum arc plasma generation with the dc ion-beam extraction. The possibility of formation of pseudo ribbon beam of metal ions with the parameters: ion beam length 0.6 m, ion current up to 0.2 A, accelerating voltage 40 kV, and ion energy up to 160 kV has been demonstrated. The pseudo ribbon ion beam is formed from dc vacuum arc plasma. The results of investigation of the vacuum arc evaporator ion-emission properties are presented. The influence of magnetic field strength near the cathode surface on the arc spot movement and ion-emission properties of vacuum-arc discharge for different cathode materials are determined. It was shown that vacuum-arc discharge stability can be reached when the magnetic field strength ranges from 40 to 70 G on the cathode surface.

  12. Separation of metal ions from aqueous solutions

    DOEpatents

    Almon, Amy C.

    1994-01-01

    A process and apparatus for quantitatively and selectively separating metal ions from mixtures thereof in aqueous solution. The apparatus includes, in combination, a horizontal electrochemical flow cell containing flow bulk electrolyte solution and an aqueous, metal ion-containing solution, the cell containing a metal mesh working electrode, a counter electrode positioned downstream from the working electrode, an independent variable power supply/potentiostat positioned outside of the flow cell and connected to the electrodes, and optionally a detector such as a chromatographic detector, positioned outside the flow cell. This apparatus and its operation has significant application where trace amounts of metal ions are to be separated.

  13. Plasma immersion ion implantation for reducing metal ion release

    SciTech Connect

    Diaz, C.; Garcia, J. A.; Maendl, S.; Pereiro, R.; Fernandez, B.; Rodriguez, R. J.

    2012-11-06

    Plasma immersion ion implantation of Nitrogen and Oxygen on CoCrMo alloys was carried out to improve the tribological and corrosion behaviors of these biomedical alloys. In order to optimize the implantation results we were carried experiments at different temperatures. Tribocorrosion tests in bovine serum were used to measure Co, Cr and Mo releasing by using Inductively Coupled Plasma Mass Spectrometry analysis after tests. Also, X-ray Diffraction analysis were employed in order to explain any obtained difference in wear rate and corrosion tests. Wear tests reveals important decreases in rate of more than one order of magnitude for the best treatment. Moreover decreases in metal release were found for all the implanted samples, preserving the same corrosion resistance of the unimplanted samples. Finally this paper gathers an analysis, in terms of implantation parameters and achieved properties for industrial implementation of these treatments.

  14. Metallic ion production with the dione EBIS

    NASA Astrophysics Data System (ADS)

    Visentin, B.; Courtois, A.; Gobin, R.; Harrault, F.; Leroy, P. A.

    1997-01-01

    We report the first quantitative results obtained with metallic elements injected from an Hollow Cathode ion source into the Dioné EBIS. These results are concerned with the charge state distribution of gold ions, with a maximum for Au47+ of (1,3 × 107 ions), and the highest charge state detectable on a wire profiler of Au63+. The Au50+ ions have been captured in Mimas storage synchrotron, and an Fe20+ ion beam has been accelerated in the Saturne synchrotron. The Hollow Cathode ion source lifetime has been tested on a long term basis (Au1+ injected into Dioné during six weeks, 24 hours per day). This source, able to produce metallic ions with any buffer gas (Ne, Ar, Kr, Xe, or N) and is also used to inject gaseous ions into Dioné.

  15. Metal ion adsorption at the ionic liquid-mica interface

    NASA Astrophysics Data System (ADS)

    McDonald, Samila; Elbourne, Aaron; Warr, Gregory G.; Atkin, Rob

    2015-12-01

    with the IL cation and adsorb to mica charge sites. In this work amplitude modulated atomic force microscopy (AM-AFM) has been used to probe metal ion adsorption at the interface of mica with propylammonium nitrate (PAN), a room temperature IL. Lithium, sodium, potassium, magnesium and calcium nitrate salts were added to PAN at a concentration of ~60 mM. Aluminum nitrate was also investigated, but only at 5 mM because its solubility in PAN is much lower. The AM-AFM images obtained when the metal ions were present are strikingly different to that of pure PAN, indicating that the ions compete effectively with the propylammonium cation and adsorb to negatively charged sites on the mica surface despite their much lower concentration. This is a consequence of electrostatic attractions between the mica charge sites and the metal ions being significantly stronger than for the propylammonium cation; compared to the metal ions the propylammonium charged group is relatively constrained sterically. A distinct honeycomb pattern is noted for the PAN + Al3+ system, less obviously for the divalent ions and not at all for monovalent ions. This difference is attributed to the strength of electrostatic interactions between metal ions and mica charge sites increasing with the ion charge, which means that divalent and (particularly) trivalent ions are located more precisely above the charged sites of the mica lattice. The images obtained allow important distinctions between metal ion adsorption at mica-water and mica-PAN interfaces to be made. Electronic supplementary information (ESI) available: Ion diameter distribution (grain size analysis) for the PAN + metal ion solutions. See DOI: 10.1039/c5nr05833c

  16. An optical dosimeter for monitoring heavy metal ions in water

    NASA Astrophysics Data System (ADS)

    Mignani, Anna G.; Regan, Fiona; Leamy, D.; Mencaglia, A. A.; Ciaccheri, L.

    2005-05-01

    This work presents an optochemical dosimeter for determining and discriminating nickel, copper, and cobalt ions in water that can be used as an early warning system for water pollution. An inexpensive fiber optic spectrophotometer monitors the sensor's spectral behavior under exposure to water solutions of heavy metal ions in the 1-10 mg/l concentration range. The Principal Component Analysis (PCA) method quantitatively determines the heavy metals and discriminates their type and combination.

  17. Analysis of heterogeneous water vapor uptake by metal iodide cluster ions via differential mobility analysis-mass spectrometry

    SciTech Connect

    Oberreit, Derek; Rawat, Vivek K.; Larriba-Andaluz, Carlos; Ouyang, Hui; McMurry, Peter H.; Hogan, Christopher J.

    2015-09-14

    The sorption of vapor molecules onto pre-existing nanometer sized clusters is of importance in understanding particle formation and growth in gas phase environments and devising gas phase separation schemes. Here, we apply a differential mobility analyzer-mass spectrometer based approach to observe directly the sorption of vapor molecules onto iodide cluster ions of the form (MI){sub x}M{sup +} (x = 1-13, M = Na, K, Rb, or Cs) in air at 300 K and with water saturation ratios in the 0.01-0.64 range. The extent of vapor sorption is quantified in measurements by the shift in collision cross section (CCS) for each ion. We find that CCS measurements are sensitive enough to detect the transient binding of several vapor molecules to clusters, which shift CCSs by only several percent. At the same time, for the highest saturation ratios examined, we observed CCS shifts of up to 45%. For x < 4, cesium, rubidium, and potassium iodide cluster ions are found to uptake water to a similar extent, while sodium iodide clusters uptake less water. For x ≥ 4, sodium iodide cluster ions uptake proportionally more water vapor than rubidium and potassium iodide cluster ions, while cesium iodide ions exhibit less uptake. Measured CCS shifts are compared to predictions based upon a Kelvin-Thomson-Raoult (KTR) model as well as a Langmuir adsorption model. We find that the Langmuir adsorption model can be fit well to measurements. Meanwhile, KTR predictions deviate from measurements, which suggests that the earliest stages of vapor uptake by nanometer scale species are not well described by the KTR model.

  18. Analysis of heterogeneous water vapor uptake by metal iodide cluster ions via differential mobility analysis-mass spectrometry

    NASA Astrophysics Data System (ADS)

    Oberreit, Derek; Rawat, Vivek K.; Larriba-Andaluz, Carlos; Ouyang, Hui; McMurry, Peter H.; Hogan, Christopher J.

    2015-09-01

    The sorption of vapor molecules onto pre-existing nanometer sized clusters is of importance in understanding particle formation and growth in gas phase environments and devising gas phase separation schemes. Here, we apply a differential mobility analyzer-mass spectrometer based approach to observe directly the sorption of vapor molecules onto iodide cluster ions of the form (MI)xM+ (x = 1-13, M = Na, K, Rb, or Cs) in air at 300 K and with water saturation ratios in the 0.01-0.64 range. The extent of vapor sorption is quantified in measurements by the shift in collision cross section (CCS) for each ion. We find that CCS measurements are sensitive enough to detect the transient binding of several vapor molecules to clusters, which shift CCSs by only several percent. At the same time, for the highest saturation ratios examined, we observed CCS shifts of up to 45%. For x < 4, cesium, rubidium, and potassium iodide cluster ions are found to uptake water to a similar extent, while sodium iodide clusters uptake less water. For x ≥ 4, sodium iodide cluster ions uptake proportionally more water vapor than rubidium and potassium iodide cluster ions, while cesium iodide ions exhibit less uptake. Measured CCS shifts are compared to predictions based upon a Kelvin-Thomson-Raoult (KTR) model as well as a Langmuir adsorption model. We find that the Langmuir adsorption model can be fit well to measurements. Meanwhile, KTR predictions deviate from measurements, which suggests that the earliest stages of vapor uptake by nanometer scale species are not well described by the KTR model.

  19. Analysis of heterogeneous water vapor uptake by metal iodide cluster ions via differential mobility analysis-mass spectrometry.

    PubMed

    Oberreit, Derek; Rawat, Vivek K; Larriba-Andaluz, Carlos; Ouyang, Hui; McMurry, Peter H; Hogan, Christopher J

    2015-09-14

    The sorption of vapor molecules onto pre-existing nanometer sized clusters is of importance in understanding particle formation and growth in gas phase environments and devising gas phase separation schemes. Here, we apply a differential mobility analyzer-mass spectrometer based approach to observe directly the sorption of vapor molecules onto iodide cluster ions of the form (MI)xM(+) (x = 1-13, M = Na, K, Rb, or Cs) in air at 300 K and with water saturation ratios in the 0.01-0.64 range. The extent of vapor sorption is quantified in measurements by the shift in collision cross section (CCS) for each ion. We find that CCS measurements are sensitive enough to detect the transient binding of several vapor molecules to clusters, which shift CCSs by only several percent. At the same time, for the highest saturation ratios examined, we observed CCS shifts of up to 45%. For x < 4, cesium, rubidium, and potassium iodide cluster ions are found to uptake water to a similar extent, while sodium iodide clusters uptake less water. For x ≥ 4, sodium iodide cluster ions uptake proportionally more water vapor than rubidium and potassium iodide cluster ions, while cesium iodide ions exhibit less uptake. Measured CCS shifts are compared to predictions based upon a Kelvin-Thomson-Raoult (KTR) model as well as a Langmuir adsorption model. We find that the Langmuir adsorption model can be fit well to measurements. Meanwhile, KTR predictions deviate from measurements, which suggests that the earliest stages of vapor uptake by nanometer scale species are not well described by the KTR model. PMID:26374028

  20. [Trace analysis of heavy metal ions in electroplate waste water by capillary electrophoresis with visual offline sample stacking via moving neutralization boundary].

    PubMed

    Fan, Yinping; Li, Shan; Fan, Liuyin; Cao, Chengxi

    2012-08-01

    A moving neutralization boundary (MNB) was developed as a novel model of visual offline sample stacking for the trace analysis of heavy metal ions (HMIs) by capillary zone electrophoresis (CZE). In the stacking system, the motion direction of MNB to cathode was used with 2.1 mmol/L HCl-98 mmol/L KCl-trace metal ions in the anodic solution and 4.0 mmol/L NaOH-96 mmol/L KCl in the cathodic solution. The voltage was constant at 180 V and the flow rate of the anolyte and catholyte was 1 mL/min. The metal ions in the gel after stacking were detected by capillary electrophoresis. The calibration curves showed good linear relationship (r > or = 0.998 5) in the concentration range used in the experiments. The pre-concentration factors were up to 80 - 150 and the limits of detection (LODs) were 0.163, 0.256, 0.077, 0.153, 0.203, 0.062 and 0.142 mg/L for Cu(II), Zn(II), Ni(II), Mg(II), Ca(II), Cr(III) and Fe(III), respectively, obviously lower than the national standards. The intra-day and inter-day assay precisions were good (the relative standard deviations (RSDs) less than 7.42%). Finally, the developed method has been successfully used for the stacking and the detection of heavy metal ions in electroplate waste water. PMID:23256387

  1. Uptake of metal ions on humic acids

    SciTech Connect

    Pehlivan, E.; Arslan, G.

    2006-09-15

    The kinetics, the sorption capacities, pH and temperature dependence of sorption of humic acids (HAs) of Turkish brown coals with respect to Zn(II), Cu(II), Ni(II), Co(II) and Pb(II) ions were investigated, and the roles of the carboxylic and phenolic groups in the adsorption of metals ion on HAs were searched in this work. These metal ions are able to form complex compounds with carboxylic and phenolic groups of HAs. Adsorption equilibrium was achieved in between 50 and 60 min for all studied cations. HAs extracted from different brown coals have been characterized by chemical and physical methods. The chemical properties of HAs showed differences depending on the source from which they were obtained. The sorption of metals on the surface of HAs depends strongly on the pH, and sorption decreases with decreasing pH. Maximum removal of metal ions was demonstrated at pH values of 4.1-5.0. The Langmuir adsorption isotherm was used to describe observed sorption phenomena. The {Delta}G{sup 0} became negative as the temperature increased, and so the equilibrium constant decreased slightly. The investigation proved that the HAs are suitable materials for the studied heavy metal ion removal from aqueous solution and could be considered as potential material for purification of effluent polluted with toxic metal ions.

  2. ION EXCHANGE SOFTENING: EFFECTS ON METAL CONCENTRATIONS

    EPA Science Inventory

    A corrosion control pipe loop study to evaluate the effect of ion exchange water softening on metal leaching from household plumbing materials was conducted on two different water qualities having different pH's and hardness levels. The results showed that removing hardness ions ...

  3. Metal-ion recycle technology for metal electroplating waste waters

    SciTech Connect

    Sauer, N.N.; Smith, B.F.

    1993-06-01

    As a result of a collaboration with Boeing Aerospace, the authors have begun a program to identify suitable treatments or to develop new treatments for electroplating baths. The target baths are mixed-metal or alloy baths that are being integrated into the Boeing electroplating complex. These baths, which are designed to replace highly toxic chromium and cadmium baths, contain mixtures of two metals, either nickel-tungsten, nickel-zinc, or zinc-tin. This report reviews the literature and details currently available on emerging technologies that could affect recovery of metals from electroplating baths under development by Boeing Aerospace. This literature survey summarizes technologies relevant to the recovery of metals from electroplating processes. The authors expanded the scope to investigate single metal ion recovery technologies that could be applied to metal ion recovery from alloy baths. This review clearly showed that the electroplating industry has traditionally relied on precipitation and more recently on electrowinning as its waste treatment methods. Despite the almost ubiquitous use of precipitation to remove contaminant metal ions from waste electroplating baths and rinse waters, this technology is clearly no longer feasible for the electroplating industry for several reasons. First, disposal of unstabilized sludge is no longer allowed by law. Second, these methods are no longer adequate as metal-removal techniques because they cannot meet stringent new metal discharge limits. Third, precious resources are being wasted or discarded because these methods do not readily permit recovery of the target metal ions. As a result, emerging technologies for metal recovery are beginning to see application to electroplating waste recycle. This report summarizes current research in these areas. Included are descriptions of various membrane technologies, such as reverse osmosis and ultrafiltration, ion exchange and chelating polymer technology, and electrodialysis.

  4. Upgraded vacuum arc ion source for metal ion implantation

    SciTech Connect

    Nikolaev, A. G.; Oks, E. M.; Savkin, K. P.; Yushkov, G. Yu.; Brown, I. G.

    2012-02-15

    Vacuum arc ion sources have been made and used by a large number of research groups around the world over the past twenty years. The first generation of vacuum arc ion sources (dubbed ''Mevva,'' for metal vapor vacuum arc) was developed at Lawrence Berkeley National Laboratory in the 1980s. This paper considers the design, performance parameters, and some applications of a new modified version of this kind of source which we have called Mevva-V.Ru. The source produces broad beams of metal ions at an extraction voltage of up to 60 kV and a time-averaged ion beam current in the milliampere range. Here, we describe the Mevva-V.Ru vacuum arc ion source that we have developed at Tomsk and summarize its beam characteristics along with some of the applications to which we have put it. We also describe the source performance using compound cathodes.

  5. Functional Identification of Catalytic Metal Ion Binding Sites within RNA

    PubMed Central

    2005-01-01

    The viability of living systems depends inextricably on enzymes that catalyze phosphoryl transfer reactions. For many enzymes in this class, including several ribozymes, divalent metal ions serve as obligate cofactors. Understanding how metal ions mediate catalysis requires elucidation of metal ion interactions with both the enzyme and the substrate(s). In the Tetrahymena group I intron, previous work using atomic mutagenesis and quantitative analysis of metal ion rescue behavior identified three metal ions (MA, MB, and MC) that make five interactions with the ribozyme substrates in the reaction's transition state. Here, we combine substrate atomic mutagenesis with site-specific phosphorothioate substitutions in the ribozyme backbone to develop a powerful, general strategy for defining the ligands of catalytic metal ions within RNA. In applying this strategy to the Tetrahymena group I intron, we have identified the pro-SP phosphoryl oxygen at nucleotide C262 as a ribozyme ligand for MC. Our findings establish a direct connection between the ribozyme core and the functionally defined model of the chemical transition state, thereby extending the known set of transition-state interactions and providing information critical for the application of the recent group I intron crystallographic structures to the understanding of catalysis. PMID:16092891

  6. Bioavailability of Metal Ions and Evolutionary Adaptation

    PubMed Central

    Hong Enriquez, Rolando P.; Do, Trang N.

    2012-01-01

    The evolution of life on earth has been a long process that began nearly 3.5 × 109 years ago. In their initial moments, evolution was mainly influenced by anaerobic environments; with the rise of O2 and the corresponding change in bioavailability of metal ions, new mechanisms of survival were created. Here we review the relationships between ancient atmospheric conditions, metal ion bioavailability and adaptation of metals homeostasis during early evolution. A general picture linking geochemistry, biochemistry and homeostasis is supported by the reviewed literature and is further illustrated in this report using simple database searches. PMID:25371266

  7. Computational Design of Metal Ion Sequestering Agents

    SciTech Connect

    Hay, Benjamin P.; Rapko, Brian M.

    2006-06-01

    Organic ligands that exhibit a high degree of metal ion recognition are essential precursors for developing separation processes and sensors for metal ions. Since the beginning of the nuclear era, much research has focused on discovering ligands that target specific radionuclides. Members of the Group 1A and 2A cations (e.g., Cs, Sr, Ra) and the f-block metals (actinides and lanthanides) are of primary concern to DOE. Although there has been some success in identifying ligand architectures that exhibit a degree of metal ion recognition, the ability to control binding affinity and selectivity remains a significant challenge. The traditional approach for discovering such ligands has involved lengthy programs of organic synthesis and testing that, in the absence of reliable methods for screening compounds before synthesis, have resulted in much wasted research effort.

  8. Computational Design of Metal Ion Sequestering Agents

    SciTech Connect

    Hay, Benjamin P.; Rapko, Brian M.

    2005-06-15

    Organic ligands that exhibit a high degree of metal ion recognition are essential precursors for developing separation processes and sensors for metal ions. Since the beginning of the nuclear era, much research has focused on discovering ligands that target specific radionuclides. Members of the Group 1A and 2A cations (e.g., Cs, Sr, Ra) and the f-block metals (actinides and lanthanides) are of primary concern to DOE. Although there has been some success in identifying ligand architectures that exhibit a degree of metal ion recognition, the ability to control binding affinity and selectivity remains a significant challenge. The traditional approach for discovering such ligands has involved lengthy programs of organic synthesis and testing that, in the absence of reliable methods for screening compounds before synthesis, have resulted in much wasted research effort.

  9. Computational Design of Metal Ion Sequestering Agents

    SciTech Connect

    Hay, Benjamin P.; Rapko, Brian M.

    2005-06-15

    Organic ligands that exhibit a high degree of metal ion recognition are essential precursors for developing separation processes and sensors for metal ions. Since the beginning of the nuclear era, much research has focused on discovering ligands that target specific radionuclides. Members of the Group 1A and 2A cations (e.g., Cs, Sr, Ra) and the f-block metals (actinides and lanthanides) are of primary concern to DOE. Although there has been some success in identifying ligand architectures that exhibit a degree of metal ion recognition, the ability to control binding affinity and selectivity remains a significant challenge. The traditional approach for discovering such ligands has involved lengthy programs of organic synthesis and testing that, in the absence of reliable methods for screening compounds before synthesis, have resulted in much wasted research effort. This project seeks to enhance and strengthen the traditional approach through computer-aided design of new and improved host molecules. Accurate electronic structure calculations are coupled with experimental data to provide fundamental information about ligand structure and the nature of metal-donor group interactions (design criteria). This fundamental information then is used in a molecular mechanics model (MM) that helps us rapidly screen proposed ligand architectures and select the best members from a set of potential candidates. By using combinatorial methods, molecule building software has been developed that generates large numbers of candidate architectures for a given set of donor groups. The specific goals of this project are: • further understand the structural and energetic aspects of individual donor group- metal ion interactions and incorporate this information within the MM framework • further develop and evaluate approaches for correlating ligand structure with reactivity toward metal ions, in other words, screening capability • use molecule structure building software to generate

  10. The Effect of Complex Formation upon the Redox Potentials of Metallic Ions. Cyclic Voltammetry Experiments.

    ERIC Educational Resources Information Center

    Ibanez, Jorge G.; And Others

    1988-01-01

    Describes experiments in which students prepare in situ soluble complexes of metal ions with different ligands and observe and estimate the change in formal potential that the ion undergoes upon complexation. Discusses student formation and analysis of soluble complexes of two different metal ions with the same ligand. (CW)

  11. Metal analysis of cotton

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seven varieties of cotton were investigated for 8 metal ions (K, Na, Mg, Ca, Fe, Cu, Zn, and Mn) using Inductively Coupled Plasma-Optical Emission Spectroscopy. All of the varieties were grown at the same location. Half of the samples were dry (rain fed only) and the other were well-watered (irrigat...

  12. Data mining of metal ion environments present in protein structures

    PubMed Central

    Zheng, Heping; Chruszcz, Maksymilian; Lasota, Piotr; Lebioda, Lukasz; Minor, Wladek

    2010-01-01

    Analysis of metal-protein interaction distances, coordination numbers, B-factors (displacement parameters), and occupancies of metal binding sites in protein structures determined by X-ray crystallography and deposited in the PDB shows many unusual values and unexpected correlations. By measuring the frequency of each amino acid in metal ion binding sites, the positive or negative preferences of each residue for each type of cation were identified. Our approach may be used for fast identification of metal-binding structural motifs that cannot be identified on the basis of sequence similarity alone. The analysis compares data derived separately from high and medium resolution structures from the PDB with those from very high resolution small-molecule structures in the Cambridge Structural Database (CSD). For high resolution protein structures, the distribution of metal-protein or metal-water interaction distances agrees quite well with data from CSD, but the distribution is unrealistically wide for medium (2.0 – 2.5 Å) resolution data. Our analysis of cation B-factors versus average B-factors of atoms in the cation environment reveals substantial numbers of structures contain either an incorrect metal ion assignment or an unusual coordination pattern. Correlation between data resolution and completeness of the metal coordination spheres is also found. PMID:18614239

  13. Data mining of metal ion environments present in protein structures.

    PubMed

    Zheng, Heping; Chruszcz, Maksymilian; Lasota, Piotr; Lebioda, Lukasz; Minor, Wladek

    2008-09-01

    Analysis of metal-protein interaction distances, coordination numbers, B-factors (displacement parameters), and occupancies of metal-binding sites in protein structures determined by X-ray crystallography and deposited in the PDB shows many unusual values and unexpected correlations. By measuring the frequency of each amino acid in metal ion-binding sites, the positive or negative preferences of each residue for each type of cation were identified. Our approach may be used for fast identification of metal-binding structural motifs that cannot be identified on the basis of sequence similarity alone. The analysis compares data derived separately from high and medium-resolution structures from the PDB with those from very high-resolution small-molecule structures in the Cambridge Structural Database (CSD). For high-resolution protein structures, the distribution of metal-protein or metal-water interaction distances agrees quite well with data from CSD, but the distribution is unrealistically wide for medium (2.0-2.5A) resolution data. Our analysis of cation B-factors versus average B-factors of atoms in the cation environment reveals substantial numbers of structures contain either an incorrect metal ion assignment or an unusual coordination pattern. Correlation between data resolution and completeness of the metal coordination spheres is also found. PMID:18614239

  14. Effect of metal ions on positron annihilation characteristics in metal ion containing epoxies

    NASA Technical Reports Server (NTRS)

    Singh, J. J.; St. Clair, A. K.; Stoakley, D. M.; Holt, W. H.; Mock, W., Jr.

    1984-01-01

    In the course of developing improved moisture-resistant epoxy resins, two different types of epoxy resins containing variable mole ratios of chromium ions per polymer repeat unit were developed. Positron annihilation characteristics have been investigated in these resins as a function of their metal ion content. In both cases, the presence of metal ions reduces the lifetime as well as the intensity of the long life component. The long life component intensity reduction is considerably more pronounced than the lifetime reduction. These results have been discussed in terms of increased unpaired electron density at Ps formation sites due to the presence of chromium ions in the matrix.

  15. IMMUNOASSAYS FOR METAL IONS. (R824029)

    EPA Science Inventory

    Abstract

    Antibodies that recognize chelated forms of metal ions have been used to construct immunoassays for Cd(II), Hg(II), Pb(II), and Ni(II). In this paper, the format of these immunoassays is described and the binding properties of three monoclonal antibodies direc...

  16. Material Removes Heavy Metal Ions From Water

    NASA Technical Reports Server (NTRS)

    Philipp, Warren H., Jr.; Street, Kenneth W.; Hill, Carol; Savino, Joseph M.

    1995-01-01

    New high capacity ion-exchange polymer material removes toxic metal cations from contaminated water. Offers several advantages. High sensitivities for such heavy metals as lead, cadmium, and copper and capable of reducing concentrations in aqueous solutions to parts-per-billion range. Removes cations even when calcium present. Material made into variety of forms, such as thin films, coatings, pellets, and fibers. As result, adapted to many applications to purify contaminated water, usually hard wherever found, whether in wastewater-treatment systems, lakes, ponds, industrial plants, or homes. Another important feature that adsorbed metals easily reclaimed by either destructive or nondestructive process. Other tests show ion-exchange polymer made inexpensively; easy to use; strong, flexible, not easily torn; and chemically stable in storage, in aqueous solutions, and in acidic or basic solution.

  17. The role of metal ion-ligand interactions during divalent metal ion adsorption.

    PubMed

    Eldridge, Daniel S; Crawford, Russell J; Harding, Ian H

    2015-09-15

    A suite of seven different divalent metal ions (Ca(II), Cd(II), Cu(II), Mg(II), Ni(II), Pb(II), Zn(II)) was adsorbed from solution onto two Fe2O3 samples, quartz SiO2 and three different amphoteric polystyrene latices (containing amine and carboxyl functional groups). For the metal oxides, a high correlation was observed between the pH at which 50% of the metal was removed from solution (pH50) and the first hydrolysis constant for the metal ion (pK1). For the polystyrene latices, a much higher correlation was observed between the pH50 and pKc (equilibrium constant describing metal-carboxyl affinity) as opposed to pK1. These observations provide evidence of a strong relationship that exists between a metal's affinity for a particular ligand in solution and for that metal ion's affinity for the same ligand present as part of an adsorbing surface. The isoelectric point of the amphoteric latex surface can be increased by decreasing the carboxyl content of the latex surface. For all 7 metal ions, this resulted in a substantial decrease, for any given pH, in adsorption. We suggest that this may be partly due to the decreased carboxyl content, but is dominantly attributable to the presence of less favorable electrostatic conditions. This, in turn, demonstrates that electrostatics play a controlling role in metal ion adsorption onto amphoteric latex surfaces and, in addition to the nature of the metal ion, also controls the pH at which adsorption takes place. PMID:26001134

  18. Ion irradiation effects on metallic nanocrystals

    NASA Astrophysics Data System (ADS)

    Kluth, P.; Johannessen, B.; Giulian, R.; Schnohr, C. S.; Foran, G. J.; Cookson, D. J.; Byrne, A. P.; Ridgway, M. C.

    We have investigated structural and morphological properties of metallic nanocrystals (NCs) exposed to ion irradiation. NCs were characterized by transmission electron microscopy in combination with advanced synchrotron-based analytical techniques, in particular X-ray absorption spectroscopy and small-angle X-ray scattering. A number of different effects were observed depending on the irradiation conditions. At energies where nuclear stopping is predominant, structural disorder/amorphization followed by inverse Ostwald ripening/dissolution due to ion beam mixing was observed for Au and Cu NCs embedded in SiO2. The ion-irradiation-induced crystalline to amorphous transition in the NCs, which cannot be achieved in the corresponding bulk metals, was attributed to their initially higher structural energy as compared to bulk material and possibly preferential nucleation of the amorphous phase at the NC/SiO2 interface. At very high irradiation energies (swift heavy ion irradiation), where the energy loss is nearly entirely due to electronic stopping, a size-dependent shape transformation of the NCs from spheres to rod like shapes was apparent in Au NCs. Our preliminary results are in good agreement with considerations on melting of the NCs in the ion track as one mechanism involved in the shape transformation.

  19. Ion irradiation effects on metallic nanocrystals

    SciTech Connect

    Kluth, P.; Johannessen, B.; Giulian, R.; Schnohr, C.S.; Foran, G.J.; Cookson, D.J.; Byrne, A.P.; Ridgway, M.C.

    2008-04-02

    We have investigated structural and morphological properties of metallic nanocrystals (NCs) exposed to ion irradiation. NCs were characterized by transmission electron microscopy in combination with advanced synchrotron-based analytical techniques, in particular X-ray absorption spectroscopy and small-angle X-ray scattering. A number of different effects were observed depending on the irradiation conditions. At energies where nuclear stopping is predominant, structural disorder/amorphization followed by inverse Ostwald ripening/dissolution due to ion beam mixing was observed for Au and Cu NCs embedded in SiO{sub 2}. The ion-irradiation-induced crystalline to amorphous transition in the NCs, which cannot be achieved in the corresponding bulk metals, was attributed to their initially higher structural energy as compared to bulk material and possibly preferential nucleation of the amorphous phase at the NC/SiO{sub 2} interface. At very high irradiation energies (swift heavy ion irradiation), where the energy loss is nearly entirely due to electronic stopping, a size-dependent shape transformation of the NCs from spheres to rod like shapes was apparent in Au NCs. Our preliminary results are in good agreement with considerations on melting of the NCs in the ion track as one mechanism involved in the shape transformation.

  20. Electrohydrostatic analysis of equilibrium shape and stability of stressed conducting fluids: Application to liquid metal ion sources

    SciTech Connect

    Chung, M.; Miskovsky, N.M.; Cutler, P.H.; Feuchtwang, T.E.; Kazes, E.

    1987-11-01

    An exact mathematical treatment of the problem of an electrically stressed fluid from zero field to the onset of instability gives rise to the nonlinear electrohydrodynamic equations which, in general, are not amenable to analytic solution. To make the problem more tractable, one considers two limiting regimes, the electrohydrostatic (EHS) and the electrohydrodynamic (EHD) limits. In the EHS case, the fields and the velocities are assumed to be small so that quasistatic equilibrium exists and the fluid surface is essentially at rest. In this paper we consider the electrohydrostatic analysis of the equilibrium shape and stability of the electrically stressed fluids. The current work reintroduces the EHS stability criterion due to Zeleny, as well as a new set of equations and numerical procedure for analyzing the stability of an axially symmetric fluid with an arbitrary shaped surface. These are contrasted with a stability criterion, introduced by Taylor, which it is argued, is only an equilibrium condition and not a proper criterion for analyzing the general stability of electrified fluids. The Taylor and Zeleny criteria are applied to fluid sources modeled as simple coordinate surfaces, such as the cone, the cusp, and the hyperboloid. These results lead to a new physical interpretation of the onset of fluid instability in the EHS limit. A set of partial differential equations is derived, whose solution describes the equilibrium shape of a conducting fluid as a function of the applied electric field. Numerical results are presented for the evolution of the equilibrium shapes of several liquid metals as a function of the applied voltage. Values of the critical or breakdown voltage are obtained from these results and found to be in good agreement with experiment. Finally, the EHS analysis indicates that a realistic and accurate treatment of the onset of instability requires fluid flow in a dynamical model.

  1. Complexing of metal ions by humic substances

    SciTech Connect

    Bryan, N.D.; Zhang, Y.; Jones, M.N.

    1995-12-31

    The interaction of metal ions with humic substances is being studied using two different techniques. UV-scanning ultracentrifugation is being used to determine molecular weights and to investigate changes in aggregation brought about by metal ion complexation. The relationship between cation charge and conformation of the humic ligands is also being investigated. The complexation of actinide elements (U, Np, Pu, Am) by humic substances from soils contaminated by both natural processes and by low-level effluent releases is also being studied. Gel permeation chromatography has been used to show both that different fractions of humic substances vary greatly in their effectiveness as ligands and that different actinide elements associate with different fractions. These studies have also shown that uranium desorption is kinetically controlled by humic substances.

  2. Interplay of metal ions and urease.

    PubMed

    Carter, Eric L; Flugga, Nicholas; Boer, Jodi L; Mulrooney, Scott B; Hausinger, Robert P

    2009-01-01

    Urease, the first enzyme to be crystallized, contains a dinuclear nickel metallocenter that catalyzes the decomposition of urea to produce ammonia, a reaction of great agricultural and medical importance. Several mechanisms of urease catalysis have been proposed on the basis of enzyme crystal structures, model complexes, and computational efforts, but the precise steps in catalysis and the requirement of nickel versus other metals remain unclear. Purified bacterial urease is partially activated via incubation with carbon dioxide plus nickel ions; however, in vitro activation also has been achieved with manganese and cobalt. In vivo activation of most ureases requires accessory proteins that function as nickel metallochaperones and GTP-dependent molecular chaperones or play other roles in the maturation process. In addition, some microorganisms control their levels of urease by metal ion-dependent regulatory mechanisms. PMID:20046957

  3. Metal hydrides for lithium-ion batteries.

    PubMed

    Oumellal, Y; Rougier, A; Nazri, G A; Tarascon, J-M; Aymard, L

    2008-11-01

    Classical electrodes for Li-ion technology operate via an insertion/de-insertion process. Recently, conversion electrodes have shown the capability of greater capacity, but have so far suffered from a marked hysteresis in voltage between charge and discharge, leading to poor energy efficiency and voltages. Here, we present the electrochemical reactivity of MgH(2) with Li that constitutes the first use of a metal-hydride electrode for Li-ion batteries. The MgH(2) electrode shows a large, reversible capacity of 1,480 mAh g(-1) at an average voltage of 0.5 V versus Li(+)/Li(o) which is suitable for the negative electrode. In addition, it shows the lowest polarization for conversion electrodes. The electrochemical reaction results in formation of a composite containing Mg embedded in a LiH matrix, which on charging converts back to MgH(2). Furthermore, the reaction is not specific to MgH(2), as other metal or intermetallic hydrides show similar reactivity towards Li. Equally promising, the reaction produces nanosized Mg and MgH(2), which show enhanced hydrogen sorption/desorption kinetics. We hope that such findings can pave the way for designing nanoscale active metal elements with applications in hydrogen storage and lithium-ion batteries. PMID:18849978

  4. Metal assisted focused-ion beam nanopatterning

    NASA Astrophysics Data System (ADS)

    Kannegulla, Akash; Cheng, Li-Jing

    2016-09-01

    Focused-ion beam milling is a versatile technique for maskless nanofabrication. However, the nonuniform ion beam profile and material redeposition tend to disfigure the surface morphology near the milling areas and degrade the fidelity of nanoscale pattern transfer, limiting the applicability of the technique. The ion-beam induced damage can deteriorate the performance of photonic devices and hinders the precision of template fabrication for nanoimprint lithography. To solve the issue, we present a metal assisted focused-ion beam (MAFIB) process in which a removable sacrificial aluminum layer is utilized to protect the working material. The new technique ensures smooth surfaces and fine milling edges; in addition, it permits direct formation of v-shaped grooves with tunable angles on dielectric substrates or metal films, silver for instance, which are rarely achieved by using traditional nanolithography followed by anisotropic etching processes. MAFIB was successfully demonstrated to directly create nanopatterns on different types of substrates with high fidelity and reproducibility. The technique provides the capability and flexibility necessary to fabricate nanophotonic devices and nanoimprint templates.

  5. Metal assisted focused-ion beam nanopatterning.

    PubMed

    Kannegulla, Akash; Cheng, Li-Jing

    2016-09-01

    Focused-ion beam milling is a versatile technique for maskless nanofabrication. However, the nonuniform ion beam profile and material redeposition tend to disfigure the surface morphology near the milling areas and degrade the fidelity of nanoscale pattern transfer, limiting the applicability of the technique. The ion-beam induced damage can deteriorate the performance of photonic devices and hinders the precision of template fabrication for nanoimprint lithography. To solve the issue, we present a metal assisted focused-ion beam (MAFIB) process in which a removable sacrificial aluminum layer is utilized to protect the working material. The new technique ensures smooth surfaces and fine milling edges; in addition, it permits direct formation of v-shaped grooves with tunable angles on dielectric substrates or metal films, silver for instance, which are rarely achieved by using traditional nanolithography followed by anisotropic etching processes. MAFIB was successfully demonstrated to directly create nanopatterns on different types of substrates with high fidelity and reproducibility. The technique provides the capability and flexibility necessary to fabricate nanophotonic devices and nanoimprint templates. PMID:27479713

  6. Transparent monolithic metal ion containing nanophase aerogels

    SciTech Connect

    Risen, W. M., Jr.; Hu, X.; Ji, S.; Littrell, K.

    1999-12-01

    The formation of monolithic and transparent transition metal containing aerogels has been achieved through cooperative interactions of high molecular weight functionalized carbohydrates and silica precursors, which strongly influence the kinetics of gelation. After initial gelation, subsequent modification of the ligating character of the system, coordination of the group VIII metal ions, and supercritical extraction afford the aerogels. The structures at the nanophase level have been probed by photon and electron transmission and neutron scattering techniques to help elucidate the basis for structural integrity together with the small entity sizes that permit transparency in the visible range. They also help with understanding the chemical reactivities of the metal-containing sites in these very high surface area materials. These results are discussed in connection with new reaction studies.

  7. On the Metal Ion Selectivity of Oxoacid Extractants

    SciTech Connect

    Hay, Benjamin; Chagnes, Alexandre; Cote, Gerard

    2013-01-01

    Relationships between metal chelate stability, ligand basicity, and metal ion acidity are reviewed and the general applicability is illustrated by linear correlations between aqueous stability constants and ligand pKa values for 35 metals with 26 ligands. The results confirm that most individual ligands of this type exhibit a stability ordering that correlates with the Lewis acidity of the metal ion. It is concluded that the general metal ion selectivity exhibited by liquid-liquid oxoacid extractants such as carboxylic acids, -diketones, and alkylphosphoric acids reflects the intrinsic affinity of the metal ion for the negative oxygen donor ligand.

  8. Quantitative Phosphoproteome Analysis of Lysophosphatidic Acid Induced Chemotaxis applying Dual-step ¹⁸O Labeling Coupled with Immobilized Metal-ion Affinity Chromatography

    SciTech Connect

    Ding, Shi-Jian; Wang, Yingchun; Jacobs, Jon M.; Qian, Weijun; Yang, Feng; Tolmachev, Aleksey V.; Du, Xiuxia; Wang, Wei; Moore, Ronald J.; Monroe, Matthew E.; Purvine, Samuel O.; Waters, Katrina M.; Heibeck, Tyler H.; Adkins, Joshua N.; Camp, David G.; Klemke, Richard L.; Smith, Richard D.

    2008-10-01

    Reversible protein phosphorylation is a central cellular regulatory mechanism in modulating protein activity and propagating signals within cellular pathways and networks. Development of more effective methods for the simultaneous identification of phosphorylation sites and quantification of temporal changes in protein phosphorylation could provide important insights into molecular signaling mechanisms in a variety of different cellular processes. Here we present an integrated quantitative phosphoproteomics approach and its applications for comparative analysis of Cos-7 cells in response to lysophosphatidic acid (LPA) gradient stimulation. The approach combines trypsin-catalyzed 16O/18O labeling plus 16O/18O-methanol esterification labeling for quantitation, a macro- Immobilized Metal-ion Affinity Chromatography trap for phosphopeptide enrichment, and a monolithic capillary column with integrated electrospray emitter. LC separation and MS/MS is followed by neutral loss-dependent MS/MS/MS for phosphopeptide identification using a linear ion trap (LTQ)-FT mass spectrometer and complementary searching algorithms for interpreting MS/MS spectra. Protein phosphorylation involved in various signaling pathways of cell migration were identified and quantified, such as mitogen-activated protein kinase 1, dual-specificity mitogen-activated protein kinase kinase 2, and dual-specificity tyrosine-phosphorylation regulated kinase 1b, and a number of Rho GTPase-activating proteins. These results demonstrate the efficiency of this quantitative phosphoproteomics approach and its application for rapid discovery of phosphorylation events associated with gradient sensing and cell chemotaxis.

  9. Liquid metal alloy ion source based metal ion injection into a room-temperature electron beam ion source

    SciTech Connect

    Thorn, A.; Ritter, E.; Zschornack, G.; Ullmann, F.; Pilz, W.; Bischoff, L.

    2012-02-15

    We have carried out a series of measurements demonstrating the feasibility of using the Dresden electron beam ion source (EBIS)-A, a table-top sized, permanent magnet technology based electron beam ion source, as a charge breeder. Low charged gold ions from an AuGe liquid metal alloy ion source were injected into the EBIS and re-extracted as highly charged ions, thereby producing charge states as high as Au{sup 60+}. The setup, the charge breeding technique, breeding efficiencies as well as acceptance and emittance studies are presented.

  10. Theory of oxidation/reduction-induced valence transformations of metal ion dopants in oxide crystals mediated by oxide-vacancy diffusion: I. Thermodynamic analysis

    NASA Astrophysics Data System (ADS)

    Sinder, M.; Burshtein, Z.; Pelleg, J.

    2014-04-01

    We consider theoretically valence transformations of doping metal ions in oxide crystals induced by oxidation and reduction obtained by changes in the ambient oxygen partial pressure. Three types of oxygen vacancies are assumed to mediate transformations: neutral, singly ionized, and doubly ionized. We provide thermodynamic equilibrium analyses, yielding concentration relations among the oxygen vacancy, metal ions, holes and electrons as functions of the ambient oxygen pressure. The results suggest that experimental study of different species concentrations at thermodynamic equilibrium as functions of pressure and temperature should allow assessment of various reversible reaction constants controlling the process. In the Part II companion paper, the kinetic (diffusion) characteristics are considered in detail.

  11. Liquid metal ion source assembly for external ion injection into an electron string ion source (ESIS)

    NASA Astrophysics Data System (ADS)

    Segal, M. J.; Bark, R. A.; Thomae, R.; Donets, E. E.; Donets, E. D.; Boytsov, A.; Ponkin, D.; Ramsdorf, A.

    2016-02-01

    An assembly for a commercial Ga+ liquid metal ion source in combination with an ion transportation and focusing system, a pulse high-voltage quadrupole deflector, and a beam diagnostics system has been constructed in the framework of the iThemba LABS (Cape Town, South Africa)—JINR (Dubna, Russia) collaboration. First, results on Ga+ ion beam commissioning will be presented. Outlook of further experiments for measurements of charge breeding efficiency in the electron string ion source with the use of external injection of Ga+ and Au+ ion beams will be reported as well.

  12. Metal ion binding to iron oxides

    NASA Astrophysics Data System (ADS)

    Ponthieu, M.; Juillot, F.; Hiemstra, T.; van Riemsdijk, W. H.; Benedetti, M. F.

    2006-06-01

    The biogeochemistry of trace elements (TE) is largely dependent upon their interaction with heterogeneous ligands including metal oxides and hydrous oxides of iron. The modeling of TE interactions with iron oxides has been pursued using a variety of chemical models. The objective of this work is to show that it is possible to model the adsorption of protons and TE on a crystallized oxide (i.e., goethite) and on an amorphous oxide (HFO) in an identical way. Here, we use the CD-MUSIC approach in combination with valuable and reliable surface spectroscopy information about the nature of surface complexes of the TE. The other objective of this work is to obtain generic parameters to describe the binding of the following elements (Cd, Co, Cu, Ni, Pb, and Zn) onto both iron oxides for the CD-MUSIC approach. The results show that a consistent description of proton and metal ion binding is possible for goethite and HFO with the same set of model parameters. In general a good prediction of almost all the collected experimental data sets corresponding to metal ion binding to HFO is obtained. Moreover, dominant surface species are in agreement with the recently published surface complexes derived from X-ray absorption spectroscopy (XAS) data. Until more detailed information on the structure of the two iron oxides is available, the present option seems a reasonable approximation and can be used to describe complex geochemical systems. To improve our understanding and modeling of multi-component systems we need more data obtained at much lower metal ion to iron oxide ratios in order to be able to account eventually for sites that are not always characterized in spectroscopic studies.

  13. Rational Design of Metal Ion Sequestering Agents

    SciTech Connect

    Raymond, Kenneth N.

    2000-09-30

    The discriminate bonding of metal ions is a challenge to the synthetic chemist and a phenomenon of considerable practical importance.1 An important feature of many technical applications is the specific or preferential binding of a single metal ion in the presence of many metals. Examples range from large-volume uses (e.g. ferric EDTA as a plant food, calcium complexing agents as water softeners or anticaking formulations) to very high technology applications (technetium complexation in radiopharmaceuticals, synthetic metalloenzymes). We are interested in efficient and discriminate binding of actinides for waste stream remediation. Actinides represent a major and long-lived contaminant in nuclear waste. While the separation of actinides from other radioactive components of waste, such as Sr and Cs, is relatively well established, the separation of actinides from each other and in complex solutions (e.g. those found in tank wastes) is not as well resolved. The challenge of designing metal-specific (actinide) ligands is facilitated by examples from nature. Bacteria synthesize Fe(III)-specific ligands, called siderophores, to sequester Fe(III) from the environment and return it to the cell. The similarities between Fe(III) and Pu(IV) (their charge-to-size ratios and acidity), make the siderophores prototypical for designing actinide-specific ligands. The chelating groups present in siderophores are usually hydroxamic acids and catecholamides. We have developed derivatives of these natural products which have improved properties. The catechol derivatives are the 2,3-dihydroxyterephthalamides (TAMs), and 3,4-dihydroxysulfonamides (SFAMs), and the hydroxamic acid derivatives are three isomers of hydroxypyridinones, 1,2- HOPO, 3,2-HOPO, and 3,4-HOPO. All of these ligands are attached to molecular backbones by amides and a very important feature of HOPO and CAM ligands is a strong hydrogen bonds formed between the amide proton and the adjacent phenolic oxygen in the metal

  14. PROJECT SUMMARY. METAL ION ANALYSIS USING NEAR-INFRARED DYES AND THE "LABORATORY-ON-A-CHIP"

    EPA Science Inventory

    The primary objective of this project is to develop a sensitive and selective, portable sensor for radionuclides and heavy metals that utilizes a "laboratory-on-a-chip" platform for enabling low-cost, timely characterization of DOE remediation sites. This will be accomplished by ...

  15. Ion beam mixing of metal/fluoropolymer interfaces

    SciTech Connect

    Dennis, D. L.; Giedd, R. E.; Wang, Y. Q.; Glass, G. A.

    1999-06-10

    Ion beam mixing of metals and polymers with very low dielectric constants such as Teflon can provide many applications in the area of electronic materials. This work is a study of the 'mixing' effect of 50 keV nitrogen implanted thin metal layers on Teflon PTFE (polytetrafluoroethylene) substrates. RBS analysis shows that the distribution of thin layers of copper and chromium (approximately 300-400 A thick) through the implant layer of the Teflon depends on the reactivity of the metal. As the implant fluence is increased, the distribution of metal atoms in the polymer matrix becomes concentrated over smaller ranges near the bottom of the implant layer. In situ RGA analysis during the implantation shows the liberation of an abundance of fluorine in many different forms. This is supported by results from a NRA experiment that shows the non-uniform concentration profile of fluorine throughout the implant layer. During the implantation process, the fluorine is released through the incident ion track leaving a carbon and metal rich region near the surface of the implant layer. The fluorine density increases with depth through the implant layer making a smooth transition to the undamaged bulk Teflon below. Low dielectric materials with highly conductive surfaces, such as this one, may provide an opportunity for a broad range of new microelectronic applications.

  16. Ion beam mixing of metal/fluoropolymer interfaces

    SciTech Connect

    Dennis, D.L.; Giedd, R.E.; Wang, Y.Q.; Glass, G.A.

    1999-06-01

    Ion beam mixing of metals and polymers with very low dielectric constants such as Teflon can provide many applications in the area of electronic materials. This work is a study of the {open_quotes}mixing{close_quotes} effect of 50 keV nitrogen implanted thin metal layers on Teflon PTFE (polytetrafluoroethylene) substrates. RBS analysis shows that the distribution of thin layers of copper and chromium (approximately 300-400 {Angstrom} thick) through the implant layer of the Teflon depends on the reactivity of the metal. As the implant fluence is increased, the distribution of metal atoms in the polymer matrix becomes concentrated over smaller ranges near the bottom of the implant layer. {ital In situ} RGA analysis during the implantation shows the liberation of an abundance of fluorine in many different forms. This is supported by results from a NRA experiment that shows the non-uniform concentration profile of fluorine throughout the implant layer. During the implantation process, the fluorine is released through the incident ion track leaving a carbon and metal rich region near the surface of the implant layer. The fluorine density increases with depth through the implant layer making a smooth transition to the undamaged bulk Teflon below. Low dielectric materials with highly conductive surfaces, such as this one, may provide an opportunity for a broad range of new microelectronic applications. {copyright} {ital 1999 American Institute of Physics.}

  17. Measurement of Two-Photon Absorption Cross Section of Metal Ions by a Mass Sedimentation Approach

    PubMed Central

    Ma, Zhuo-Chen; Chen, Qi-Dai; Han, Bing; Liu, Xue-Qing; Song, Jun-Feng; Sun, Hong-Bo

    2015-01-01

    The photo-reduction of metal ions in solution induced by femtosecond laser is an important and novel method for fabricating three-dimensional metal microstructures. However, the nonlinear absorption cross section of metal ions remains unknown because its measurement is difficult. In the present study, a method based on Two-Photon Excited Sedimentation (TPES) is proposed to measure the two-photon absorption cross section (TPACS) of metal ions in solution. The power-squared dependence of the amount of sediment on the excitation intensity was confirmed, revealing that 800 nm femtosecond laser induced reduction of metal ions was a two photon absorption process. We believe that the proposed method may be applied to measure the TPACS of several metal ions, thereby opening a new avenue towards future analysis of two-photon absorption materials. PMID:26657990

  18. Measurement of Two-Photon Absorption Cross Section of Metal Ions by a Mass Sedimentation Approach.

    PubMed

    Ma, Zhuo-Chen; Chen, Qi-Dai; Han, Bing; Liu, Xue-Qing; Song, Jun-Feng; Sun, Hong-Bo

    2015-01-01

    The photo-reduction of metal ions in solution induced by femtosecond laser is an important and novel method for fabricating three-dimensional metal microstructures. However, the nonlinear absorption cross section of metal ions remains unknown because its measurement is difficult. In the present study, a method based on Two-Photon Excited Sedimentation (TPES) is proposed to measure the two-photon absorption cross section (TPACS) of metal ions in solution. The power-squared dependence of the amount of sediment on the excitation intensity was confirmed, revealing that 800 nm femtosecond laser induced reduction of metal ions was a two photon absorption process. We believe that the proposed method may be applied to measure the TPACS of several metal ions, thereby opening a new avenue towards future analysis of two-photon absorption materials. PMID:26657990

  19. Antifungal Properties of Electrically Generated Metallic Ions

    PubMed Central

    Berger, T. J.; Spadaro, J. A.; Bierman, Richard; Chapin, S. E.; Becker, R. O.

    1976-01-01

    A qualitative and quantitative investigation was undertaken to study the susceptibility of unicellular eucaryotic organisms (yeasts) to metallic cations generated by low levels of direct current. Results were characteristic of effects obtained previously using clinical and standard bacteria test organisms. The present study demonstrated that anodic silver (Ag+) at low direct currents had inhibitory and fungicidal properties. Broth dilution susceptibility tests were made on several species of Candida and one species of Torulopsis. Growth in all isolates was inhibited by concentrations of electrically generated silver ions between 0.5 and 4.7 μg/ml, and silver exhibited fungicidal properties at concentrations as low as 1.9 μg/ml. The inhibitory and fungicidal concentrations of electrically generated silver ions are lower than those reported for other silver compounds. Images PMID:1034467

  20. Metal Ion Intercalated graphitic as Transparent Electrodes

    NASA Astrophysics Data System (ADS)

    Wan, Jiayu; Bao, Wenzhong; Gu, Feng; Fuhrer, Michael; Hu, Liangbing; UMD Team

    To best utilize the performance of graphene based transparent electrodes, we novelized Li-ion intercalation in graphene, and achieved highest performance of carbon based transparent electrodes. Transmission as high as 91.7% with a sheet resistance of 3.0 ohm/sq is achieved for 19-layer LiC6, significantly higher than any other continuous transparent electrodes. The unconventional modification of ultrathin graphite optoelectronic properties is explained by the suppression of interband optical transitions and a small intraband Drude conductivity near the interband edge. To achieve low cost, large scale graphene-based transparent electrodes, we further developed Na-ion intercalated printed reduced graphene oxide (RGO) film. The larger layer-layer distance of RGO allows Na-ion intercalation, leading to simultaneously much higher DC conductivity and higher optical transmittance. Typical increase of transmittance from 36% to 79% and decrease of sheet resistance from 83 kohms/sq to 311 ohms/sq in the printed network was observed. This study demonstrated the great potential of metal-ion intercalation to improve the performance of graphene-based materials for transparent conductor applications.

  1. An artificial tongue fluorescent sensor array for identification and quantitation of various heavy metal ions.

    PubMed

    Xu, Wang; Ren, Changliang; Teoh, Chai Lean; Peng, Juanjuan; Gadre, Shubhankar Haribhau; Rhee, Hyun-Woo; Lee, Chi-Lik Ken; Chang, Young-Tae

    2014-09-01

    Herein, a small-molecule fluorescent sensor array for rapid identification of seven heavy metal ions was designed and synthesized, with its sensing mechanism mimicking that of a tongue. The photoinduced electron transfer and intramolecular charge transfer mechanism result in combinatorial interactions between sensor array and heavy metal ions, which lead to diversified fluorescence wavelength shifts and emission intensity changes. Upon principle component analysis (PCA), this result renders clear identification of each heavy metal ion on a 3D spatial dispersion graph. Further exploration provides a concentration-dependent pattern, allowing both qualitative and quantitative measurements of heavy metal ions. On the basis of this information, a "safe-zone" concept was proposed, which provides rapid exclusion of versatile hazardous species from clean water samples based on toxicity characteristic leaching procedure standards. This type of small-molecule fluorescent sensor array could open a new avenue for multiple heavy metal ion detection and simplified water quality analysis. PMID:25144824

  2. Behavior of metal ions in bioelectrochemical systems: A review

    NASA Astrophysics Data System (ADS)

    Lu, Zhihao; Chang, Dingming; Ma, Jingxing; Huang, Guangtuan; Cai, Lankun; Zhang, Lehua

    2015-02-01

    Bioelectrochemical systems (BESs) have been focused on by many researchers to treat wastewater and recover energy or valuable chemicals from wastes. In BESs, metal ions play an important role in the conductivity of solution, reactors' internal resistance, power generation, chemical production and activity of microorganisms. Additionally, the metal ions are also involved in anodic or cathodic reaction processes directly or indirectly in BESs. This paper reviews the behavior of metal ions in BESs, including (1) increase of the conductivity of electrolyte and decrease of internal resistance, (2) transfer for desalination, (3) enhancement or inhibition of the biocatalysis in anode, (4) improvement of cathodic performance by metal ions through electron acceptance or catalysis in cathodic process and (5) behavior of metal ions on membranes. Moreover, the perspectives of BESs removing heavy metal ions in wastewater or solid waste are discussed to realize recovery, reduction and detoxification simultaneously.

  3. Metal ion cooperativity in ribozyme cleavage of RNA

    PubMed Central

    Brännvall, Mathias; Kirsebom, Leif A.

    2001-01-01

    Combinations of chemical and genetic approaches were used to study the function of divalent metal ions in cleavage of RNA by the ribozyme RNase P RNA. We show that different divalent metal ions have differential effects on cleavage site recognition and rescue of cleavage activity by mixing divalent metal ions that do not promote cleavage by themselves. We conclude that efficient and correct cleavage is the result of cooperativity between divalent metal ions bound at different sites in the RNase P RNA-substrate complex. Complementation of a mutant RNase P RNA phenotype as a result of divalent metal ion replacement is demonstrated also. This finding together with other data indicate that one of the metal ions involved in this cooperativity is positioned near the cleavage site. The possibility that the Mg2+/Ca2+ ratio might regulate the activity of biocatalysts that depend on RNA for activity is discussed. PMID:11606743

  4. Nanomagnetic chelators for removal of toxic metal ions

    NASA Astrophysics Data System (ADS)

    Singh, Sarika; Barick, K. C.; Bahadur, D.

    2013-02-01

    Ethylenediamine trtraaceteic acid (EDTA) functionalized Fe3O4 nanomagnetic chelators (NMCs) were synthesized by co-precipitation method followed by in-situ grafting of EDTA. XRD and TEM analyses reveal the formation of highly crystalline single-phase Fe3O4 nanoparticles of size about 10 nm. Surface functionalization of Fe3O4 with EDTA was evident from FTIR spectroscopy, TGA analysis and zeta-potential measurement. These NMCs exhibit superparamagnetic behavior at room temperature with strong field dependent magnetic responsivity. It has been observed that NMCs have strong tendency for adsorption of various toxic metal ions (Ni2+, Cr3+, Cu2+, Cd2+, Co2+ and Pb2+) from waste-water. Furthermore, these magnetic chelators can be used as highly efficient separable and reusable material for removal of toxic metal ions.

  5. Fluorescence enhancement aided by metal ion displacement.

    PubMed

    Susini, Vanessa; Ienco, Andrea; Lucia Rossi, Veronica; Paolicchi, Aldo; Sanesi, Antonio

    2016-06-15

    Immunosensors are one of the most common platform used in clinical laboratories, in particular the class based on Enzyme Linked Fluorescent Assays (ELFA) takes advantage of the amplification step of the enzyme, usually the alkaline phosphatase, that catalyzes the hydrolysis of a fluorescent substrate leading it to fluoresce. Anyway, they suffer in sensitivity if compared to molecular diagnostic or more modern in vitro diagnostic devices. In our work, a simple and effective mechanism to enhance the fluorescent signal, and hence the sensitivity of the system, is presented. It is based on the metal ion displacement principle in which a second fluorophore, in our case Calcein Blue, quenched by a cobalt ion is add to the first one (4-MUP), and, in presence of inorganic phosphate, it will be progressively activated by the inorganic phosphate itself leading to the metal displacement. In this way Calcein Blue, newly free to fluoresce, contributes to global fluorescent signal generated by 4-MU. We have tested our proof of principle on a currently used immunoanalyzer, that is VIDAS® system (bioMérieux, Marcy l'Etoile, France) obtaining a fluorescence enhancement of about 50% for each concentration of hydrolyzed 4-MUP tested. PMID:26851581

  6. Microbial metal-ion reduction and Mars: extraterrestrial expectations?

    PubMed

    Nealson, Kenneth H; Cox, B Lea

    2002-06-01

    Dissimilatory metal-ion-reducing bacteria (DMRB) can couple the reduction of a variety of different metal ions to cellular respiration and growth. The excitement of this metabolic group lies not only in the elucidation of a new type of metabolism, but also in the potential use of these abilities for the removal of toxic organics, and in their ability to reduce (and thus, detoxify) other toxic metals, such as U(VI) and Cr(VI). This review focuses on recent advances in the study of DMRB, including the use of external electron shuttles to enhance rates of metal reduction; genome sequencing and consequent genomic and proteomic analyses; new imaging approaches for high resolution analysis of both cells and chemical components; the demonstration of fractionation of stable isotopes of iron during iron reduction; and the elucidation of the types and patterns of secondary mineral formation during metal reduction. One of the secondary minerals is magnetite, the subject of intense controversy regarding the possibility of evidence for life from the Martian meteorite ALH84001. This review thus ends with a short consideration of the evidence for magnetic 'proof' of the existence of past life on Mars. PMID:12057684

  7. Separation of traces of metal ions from sodium matrices

    NASA Technical Reports Server (NTRS)

    Korkisch, J.; Orlandini, K. A.

    1969-01-01

    Method for isolating metal ion traces from sodium matrices consists of two extractions and an ion exchange step. Extraction is accomplished by using 2-thenoyltrifluoracetone and dithizone followed by cation exchange.

  8. MeRNA: a Database of Metal Ion Binding Sites in RNAStructures

    SciTech Connect

    Stefan, Liliana R.; Zhang, Rui; Levitan, Aaron G.; Hendrix, DonnaF.; Brenner, Steven E.; Holbrook, Stephen R.

    2005-10-05

    Metal ions are essential for the folding of RNA into stable tertiary structures and for the catalytic activity of some RNA enzymes. To aid in the study of the roles of metal ions in RNA structural biology, we have created MeRNA (Metals in RNA), a comprehensive compilation of all metal binding sites identified in RNA three-dimensional structures available from the Protein Data Bank (PDB) and Nucleic Acid Database (NDB). Currently, our database contains information relating to binding of 9764 metal ions corresponding to 23 distinct elements; in 256 RNA structures. The metal ion locations were confirmed and ligands characterized using original literature references. MeRNA includes eight manually identified metal-ion binding motifs, which are described in the literature. MeRNA is searchable by PDB identifier, metal ion, method of structure determination, resolution and R-values for X-ray structure, and distance from metal to any RNA atom or to water. New structures with their respective binding motifs will be added to the database as they become available. The MeRNA database will further our understanding of the roles of metal ions in RNA folding and catalysis and have applications in structural and functional analysis, RNA design and engineering.

  9. Paramagnetic metal ions in pulsed ESR distance distribution measurements.

    PubMed

    Ji, Ming; Ruthstein, Sharon; Saxena, Sunil

    2014-02-18

    The use of pulsed electron spin resonance (ESR) to measure interspin distance distributions has advanced biophysical research. The three major techniques that use pulsed ESR are relaxation rate based distance measurements, double quantum coherence (DQC), and double electron electron resonance (DEER). Among these methods, the DEER technique has become particularly popular largely because it is easy to implement on commercial instruments and because programs are available to analyze experimental data. Researchers have widely used DEER to measure the structure and conformational dynamics of molecules labeled with the methanethiosulfonate spin label (MTSSL). Recently, researchers have exploited endogenously bound paramagnetic metal ions as spin probes as a way to determine structural constraints in metalloproteins. In this context Cu(2+) has served as a useful paramagnetic metal probe at X-band for DEER based distance measurements. Sample preparation is simple, and a coordinated-Cu(2+) ion offers limited spatial flexibility, making it an attractive probe for DEER experiments. On the other hand, Cu(2+) has a broad absorption ESR spectrum at low temperature, which leads to two potential complications. First, the Cu(2+)-based DEER time domain data has lower signal to noise ratio compared with MTSSL. Second, accurate distance distribution analysis often requires high-quality experimental data at different external magnetic fields or with different frequency offsets. In this Account, we summarize characteristics of Cu(2+)-based DEER distance distribution measurements and data analysis methods. We highlight a novel application of such measurements in a protein-DNA complex to identify the metal ion binding site and to elucidate its chemical mechanism of function. We also survey the progress of research on other metal ions in high frequency DEER experiments. PMID:24289139

  10. Programmed gradient descent biosorption of strontium ions by Saccaromyces cerevisiae and ashing analysis: A decrement solution for nuclide and heavy metal disposal.

    PubMed

    Liu, Mingxue; Dong, Faqin; Zhang, Wei; Nie, Xiaoqin; Sun, Shiyong; Wei, Hongfu; Luo, Lang; Xiang, Sha; Zhang, Gege

    2016-08-15

    One of the waste disposal principles is decrement. The programmed gradient descent biosorption of strontium ions by Saccaromyces cerevisiae regarding bioremoval and ashing process for decrement were studied in present research. The results indicated that S. cerevisiae cells showed valid biosorption for strontium ions with greater than 90% bioremoval efficiency for high concentration strontium ions under batch culture conditions. The S. cerevisiae cells bioaccumulated approximately 10% of strontium ions in the cytoplasm besides adsorbing 90% strontium ions on cell wall. The programmed gradient descent biosorption presented good performance with a nearly 100% bioremoval ratio for low concentration strontium ions after 3 cycles. The ashing process resulted in a huge volume and weight reduction ratio as well as enrichment for strontium in the ash. XRD results showed that SrSO4 existed in ash. Simulated experiments proved that sulfate could adjust the precipitation of strontium ions. Finally, we proposed a technological flow process that combined the programmed gradient descent biosorption and ashing, which could yield great decrement and allow the supernatant to meet discharge standard. This technological flow process may be beneficial for nuclides and heavy metal disposal treatment in many fields. PMID:27136735

  11. Biosorption of metal ions from aqueous solutions

    SciTech Connect

    Chen, Jiaping; Yiacoumi, Sotira

    1997-01-01

    Copper biosorption from aqueous solutions by calcium alginate is reported in this paper. The experimental section includes potentiometric titrations of biosorbents, batch equilibrium and kinetic studies of copper biosorption, as well as fixed-bed biosorption experiments. The potentiometric titration results show that the surface charge increases with decreasing pH. The biosorption of copper strongly depends on solution pH; the metal ion binding increases from 0 to 90 percent in pH ranging from 1.5 to 5.0. In addition, a decrease in ionic strength results in an increase of copper ion removal. Kinetic studies indicate that mass transfer plays an important role in the biosorption rate. Furthermore, a fixed-bed biosorption experiment shows that calcium alginate has a significant capacity for copper ion removal. The two-pK Basic Stem model successfully represents the surface charge and equilibrium biosorption experimental data. The calculation results demonstrate that the copper removal may result from the binding of free copper and its hydroxide with surface functional groups of the biosorbents.

  12. Comet Encke: Meteor metallic ion identification by mass spectrometer

    NASA Technical Reports Server (NTRS)

    Goldberg, R. A.; Aikin, A. C.

    1973-01-01

    Positive metallic ions have been measured in the earth's atmosphere between 85 and 120 km, during the period of the beta Taurids meteor shower, which is associated with Comet Encke. The ions originate during and following ablation of extraterrestrial debris by the earth's atmosphere. The enhancement of metal ion density during meteor showers is primary evidence for their extraterrestrial origin. The present results were obtained from a rocket-borne ion mass spectrometer.

  13. THE ROLES OF METAL IONS IN REGULATION BY RIBOSWITCHES

    PubMed Central

    2012-01-01

    Metal ions are required by all organisms in order to execute an array of essential molecular functions. They play a critical role in many catalytic mechanisms and structural properties. Proper homeostasis of ions is critical; levels that are aberrantly low or high are deleterious to cellular physiology. To maintain stable intracellular pools, metal ion-sensing regulatory (metalloregulatory) proteins couple metal ion concentration fluctuations with expression of genes encoding for cation transport or sequestration. However, these transcriptional-based regulatory strategies are not the only mechanisms by which organisms coordinate metal ions with gene expression. Intriguingly, a few classes of signal-responsive RNA elements have also been discovered to function as metalloregulatory agents. This suggests that RNA-based regulatory strategies can be precisely tuned to intracellular metal ion pools, functionally akin to metalloregulatory proteins. In addition to these metal-sensing regulatory RNAs, there is a yet broader role for metal ions in directly assisting the structural integrity of other signal-responsive regulatory RNA elements. In this chapter, we discuss how the intimate physicochemical relationship between metal ions and nucleic acids is important for the structure and function of metal ion- and metabolite-sensing regulatory RNAs. PMID:22010271

  14. Statistical evaluation of biogeochemical variables affecting spatiotemporal distributions of multiple free metal ion concentrations in an urban estuary.

    PubMed

    Dong, Zhao; Lewis, Christopher G; Burgess, Robert M; Coull, Brent; Shine, James P

    2016-05-01

    Free metal ion concentrations have been recognized as a better indicator of metal bioavailability in aquatic environments than total dissolved metal concentrations. However, our understanding of the determinants of free ion concentrations, especially in a metal mixture, is limited, due to underexplored techniques for measuring multiple free metal ions simultaneously. In this work, we performed statistical analyses on a large dataset containing repeated measurements of free ion concentrations of Cu, Zn, Pb, Ni, and Cd, the most commonly measured metals in seawater, at five inshore locations in Boston Harbor, previously collected using an in-situ equilibrium-based multi-metal free ion sampler, the 'Gellyfish'. We examined correlations among these five metals by season, and evaluated effects of 10 biogeochemical variables on free ion concentrations over time and location through multivariate regressions. We also explored potential clustering among the five metals through a principal component analysis. We found significant correlations among metals, with varying patterns over season. Our regression results suggest that instead of dissolved metals, pH, salinity, temperature and rainfall were the most significant determinants of free metal ion concentrations. For example, a one-unit decrease in pH was associated with a 2.2 (Cd) to 99 (Cu) times increase in free ion concentrations. This work is among the first to reveal key contributors to spatiotemporal variations in free ion concentrations, and demonstrated the usefulness of the Gellyfish sampler in routine sampling of free ions within metal mixtures and in generating data for statistical analyses. PMID:26901477

  15. Fluorescence imaging of metal ions implicated in diseases.

    PubMed

    Qian, Xuhong; Xu, Zhaochao

    2015-07-21

    Metal ions play an important role in various biological processes, their abnormal homeostasis in cells is related to many diseases, such as neurodegenerative disease, cancer and diabetes. Fluorescent imaging offers a unique route to detect metal ions in cells via a contactless and damage-free way with high spatial and temporal fidelity. Consequently, it represents a promising method to advance the understanding of physiological and pathological functions of metal ions in cell biology. In this highlight article, we will discuss recent advances in fluorescent imaging of metal ions by small-molecule sensors for understanding the role of metals in related diseases. We will also discuss challenges and opportunities for the design of small-molecule sensors for fluorescent detection of cellular metal ions as a potential method for disease diagnosis. PMID:25556818

  16. A biosystem for removal of metal ions from water

    SciTech Connect

    Kilbane, J.J. II.

    1990-01-01

    The presence of heavy metal ions in ground and surface waters constitutes a potential health risk and is an environmental concern. Moreover, processes for the recovery of valuable metal ions are of interest. Bioaccumulation or biosorption is not only a factor in assessing the environmental risk posed by metal ions; it can also be used as a means of decontamination. A biological system for the removal and recovery of metal ions from contaminated water is reported here. Exopolysaccharide-producing microorganisms, including a methanotrophic culture, are demonstrated to have superior metal binding ability, compared with other microbial cultures. This paper describes a biosorption process in which dried biomass obtained from exopolysaccharide-producing microorganisms is encapsulated in porous plastic beads and is used for metal ion binding and recovery. 22 refs., 13 figs.

  17. Metal Ion Capture Mechanism of a Copper Metallochaperone.

    PubMed

    Chakravorty, Dhruva K; Li, Pengfei; Tran, Trang T; Bayse, Craig A; Merz, Kenneth M

    2016-01-26

    A novel cation-π interaction between the bound Cu(+) metal ion and Trp44 in the periplasmic Cu(+)/Ag(+) metallochaperone Escherichia coli CusF protects Cu(+) from the oxidative influence of the periplasm. In a popular model of metal ion transfer, a conformational change in the metal binding loop disrupts the cation-π interaction and moves Trp44 aside to provide access to the occluded metal ion binding site in an "open" conformation. In this study, our molecular dynamics simulations support this putative mechanism of metal ion transfer. We find that the apoprotein undergoes a transition back and forth from the crystallographically observed "closed" state to the hypothesized open conformation over multiple microseconds. In agreement with nuclear magnetic resonance data, our simulations show that similar transitions are prohibited in Cu(+)·CusF, suggesting that the conformational transitions are gated by a metal ion-mediated second-shell hydrogen bond between metal binding residue His36 and Asp37 of the metal binding loop region. Ab initio quantum mechanical calculations indicate that metal ion binding strengthens this interaction significantly, much like what is found in the case of other metalloproteins. The study builds toward a common evolutionary role of metal ion-mediated second-shell hydrogen bonds in metalloprotein structure and function. PMID:26690586

  18. Molecular Turnstiles Regulated by Metal Ions.

    PubMed

    Wang, Guangxia; Xiao, Hongmei; He, Jiaojiao; Xiang, Junfeng; Wang, Ying; Chen, Xuebo; Che, Yanke; Jiang, Hua

    2016-04-15

    A family of novel molecular turnstiles 1-3 composed of two stators with pyridyl binding sites and a different-sized triptycene rotor was synthesized. The molecular turnstiles behave in an open state at room temperature in the absence of metal ions but display significantly different closed states in the presence of Ag(+) and Pd(2+). The Ag(+)-mediated turnstiles 1-3Ag exhibited closed states but unreadable bistability at ambient temperature because the Ag(+)-mediated macrocyclic framework is not able to restrict the rotations of the rotors; while temperature was decreased, the macrocyclic frameworks became stable enough to halt the rotations of the rotors, eventually leading to the readable closed states for 1-3Ag. In contrast, Pd(2+)-mediated macrocyclic frameworks are stable, giving rise to a detectable closed state of turnstiles 1-3Pd in a wide range of temperatures. These findings have also been supported by DFT calculations. PMID:26986992

  19. No association between serum metal ions and implant fixation in large-head metal-on-metal total hip arthroplasty

    PubMed Central

    Søballe, Kjeld; Jakobsen, Stig Storgaard; Lorenzen, Nina Dyrberg; Mechlenburg, Inger; Stilling, Maiken

    2014-01-01

    Background The mechanism of failure of metal-on-metal (MoM) total hip arthroplasty (THA) has been related to a high rate of metal wear debris, which is partly generated from the head-trunnion interface. However, it is not known whether implant fixation is affected by metal wear debris. Patients and methods 49 cases of MoM THA in 41 patients (10 women) with a mean age of 52 (28–68) years were followed with stereoradiographs after surgery and at 1, 2, and 5 years to analyze implant migration by radiostereometric analysis (RSA). Patients also participated in a 5- to 7-year follow-up with measurement of serum metal ions, questionnaires (Oxford hip score (OHS) and Harris hip score (HHS)), and measurement of cup and stem positions and systemic bone mineral density. Results At 1–2 years, mean total translation (TT) was 0.04 mm (95% CI: –0.07 to 0.14; p = 0.5) for the stems; at 2–5 years, mean TT was 0.13 mm (95% CI: –0.25 to –0.01; p = 0.03), but within the precision limit of the method. For the cups, there was no statistically significant TT or total rotation (TR) at 1–2 and 2–5 years. At 2–5 years, we found 4 cups and 5 stems with TT migrations exceeding the precision limit of the method. There was an association between cup migration and total OHS < 40 (4 patients, 4 hips; p = 0.04), but there were no statistically significant associations between cup or stem migration and T-scores < –1 (n = 10), cup and stem positions, or elevated serum metal ion levels (> 7µg/L (4 patients, 6 hips)). Interpretation Most cups and stems were well-fixed at 1–5 years. However, at 2–5 years, 4 cups and 5 stems had TT migrations above the precision limits, but these patients had serum metal ion levels similar to those of patients without measurable migrations, and they were pain-free. Patients with serum metal ion levels > 7 µg/L had migrations similar to those in patients with serum metal ion levels < 7 µg/L. Metal wear debris does not appear to influence the

  20. Synthesis, Spectral Analysis and Preliminary in Vitro Evaluation of Some Tetrapyrrolic Complexes with 3d Metal Ions.

    PubMed

    Socoteanu, Radu; Manda, Gina; Boscencu, Rica; Vasiliu, Georgiana; Oliveira, Anabela Sousa

    2015-01-01

    In this paper, two tetrapyrrolic complexes, Zn(II)-5-(3-hydroxyphenyl)-10,15,20-tris-(4-acetoxy-3-methoxyphenyl)porphyrin and Cu(II)-5-(3-hydroxyphenyl)-10,15,20-tris-(4-acetoxy-3-methoxyphenyl)porphyrin were synthesized, and characterized from a spectral and biological point of view. The study provided data concerning the behavior of identical external substituents vs. two different core insertions. Some of the properties of the proposed tetrapyrrolic structures were highlighted, having photodynamic therapy of cancer as a targeted biomedical application. Elemental analysis, NMR, FTIR and UV-Vis data in various solvents were provided. A preliminary in vitro study on normal and cancer cultured cells was carried out for biocompatibility assessment in dark conditions. The preliminary in vitro study performed on human peripheral mononuclear cells exposed to tetrapyrrolic compounds (2 µM) showed that the proposed compounds had a convenient cytotoxic profile on human normal peripheral blood mononuclear cells under dark conditions. Meanwhile, the investigated compounds reduced the number of metabolically active breast tumor MCF-7 cells, with the exception of Zn(II) complex-containing a symmetrical ligand. Accordingly, preliminary in vitro data suggest that the proposed tetrapyrrolic compounds are good candidates for PDT, as they limit tumor expansion even under dark conditions, whilst sparing normal cells. PMID:26343614

  1. Electron Capture Dissociation of Trivalent Metal Ion-Peptide Complexes

    NASA Astrophysics Data System (ADS)

    Flick, Tawnya G.; Donald, William A.; Williams, Evan R.

    2013-02-01

    With electrospray ionization from aqueous solutions, trivalent metal ions readily adduct to small peptides resulting in formation of predominantly (peptide + MT - H)2+, where MT = La, Tm, Lu, Sm, Ho, Yb, Pm, Tb, or Eu, for peptides with molecular weights below ~1000 Da, and predominantly (peptide + MT)3+ for larger peptides. ECD of (peptide + MT - H)2+ results in extensive fragmentation from which nearly complete sequence information can be obtained, even for peptides for which only singly protonated ions are formed in the absence of the metal ions. ECD of these doubly charged complexes containing MT results in significantly higher electron capture efficiency and sequence coverage than peptide-divalent metal ion complexes that have the same net charge. Formation of salt-bridge structures in which the metal ion coordinates to a carboxylate group are favored even for (peptide + MT)3+. ECD of these latter complexes for large peptides results in electron capture by the protonation site located remotely from the metal ion and predominantly c/ z fragments for all metals, except Eu3+, which undergoes a one electron reduction and only loss of small neutral molecules and b/ y fragments are formed. These results indicate that solvation of the metal ion in these complexes is extensive, which results in the electrochemical properties of these metal ions being similar in both the peptide environment and in bulk water.

  2. Metal Ion Sensors Based on DNAzymes and Related DNA Molecules

    NASA Astrophysics Data System (ADS)

    Zhang, Xiao-Bing; Kong, Rong-Mei; Lu, Yi

    2011-07-01

    Metal ion sensors are an important yet challenging field in analytical chemistry. Despite much effort, only a limited number of metal ion sensors are available for practical use because sensor design is often a trial-and-error-dependent process. DNAzyme-based sensors, in contrast, can be developed through a systematic selection that is generalizable for a wide range of metal ions. Here, we summarize recent progress in the design of DNAzyme-based fluorescent, colorimetric, and electrochemical sensors for metal ions, such as Pb2+, Cu2+, Hg2+, and UO22+. In addition, we also describe metal ion sensors based on related DNA molecules, including T-T or C-C mismatches and G-quadruplexes.

  3. Metal Ion Sensors Based on DNAzymes and Related DNA Molecules

    PubMed Central

    Kong, Rong-Mei

    2011-01-01

    Metal ion sensors are an important yet challenging field in analytical chemistry. Despite much effort, only a limited number of metal ion sensors are available for practical use because sensor design is often a trial-and-error-dependent process. DNAzyme-based sensors, in contrast, can be developed through a systematic selection that is generalizable for a wide range of metal ions. Here, we summarize recent progress in the design of DNAzyme-based fluorescent, colorimetric, and electrochemical sensors for metal ions, such as Pb2+, Cu2+, Hg2+, and UO22+ In addition, we also describe metal ion sensors based on related DNA molecules, including T-T or C-C mismatches and G-quadruplexes. PMID:21370984

  4. Multiply stripped ion generation in the metal vapor vacuum arc

    SciTech Connect

    Brown, I.G.; Feinberg, B.; Galvin, J.E.

    1986-08-01

    We consider the charge state distribution of ions produced in the metal vapor vacuum arc plasma discharge. A high current metal ion source, the MEVVA ion source, in which the ion beam is extracted from a metal vapor vacuum arc plasma, has been used to obtain the spectra of multiple charged ions produced within the cathode spots. A computer calculation of the charge state distribution that evolves within the spots via stepwide ionization of ions by electron impact provides a theoretical basis for comparison of the data. In this paper we report on the measured charge state distributions for a wide variety of metallic species and compare these results with the predictions of this theory. 55 refs.

  5. RNA structure analysis using T2 ribonuclease: detection of pH and metal ion induced conformational changes in yeast tRNAPhe.

    PubMed Central

    Vary, C P; Vournakis, J N

    1984-01-01

    We describe the use of an enzymic probe of RNA structure, T2 ribonuclease, to detect alterations of RNA conformation induced by changes in Mg2+ ion concentration and pH. T2 RNase is shown to possess single-strand specificity similar to S1 nuclease. In contrast to S1 nuclease, T2 RNase does not require divalent cations for activity. We have used this enzyme to investigate the role of Mg2+ ions in the stabilization of RNA conformation. We find that, at neutral pH, drastic reduction of the available divalent metal ions results in a decrease in the ability of T2 RNase to cleave the anticodon loop of tRNAPhe. This change accompanies an increase in the cleavage of the molecule in the T psi C and in the dihydrouracil loops. Similar treatment of Tetrahymena thermophila 5S ribosomal RNA shows that changes in magnesium ion concentration does not have a pronounced effect on the cleavage pattern produced by T2 RNase. T2 RNase activity has a broader pH range than S1 nuclease and can be used to study pH induced conformational shifts in RNA structure. We find that upon lowering the pH from 7.0 to 4.5, nucleotide D16 in the dihydrouracil loop of tRNAPhe becomes highly sensitive to T2 RNase hydrolysis. This change accompanies a decrease in the relative sensitivity of the anticodon loop to the enzyme. The role of metal ion and proton concentrations in maintenance of the functional conformation of tRNAPhe is discussed. Images PMID:6207483

  6. Structural insights into protein-metal ion partnerships.

    PubMed

    Barondeau, David P; Getzoff, Elizabeth D

    2004-12-01

    New metalloprotein structures continue to provide discoveries regarding protein-metal ion partnerships. Many recent structures reveal metal ion sites that control or are controlled by protein conformational change, including modulation by alternative splice variants and striking conformational changes. Only a few novel catalytic metal centers have been revealed recently, such as the surprising Ni-hook superoxide dismutase catalytic site and the cubane-like Mn(3)CaO(4) photosynthetic oxygen-evolving center. However, important new variations on old heme themes, breakthroughs in the fields of metal ion regulation and metallochaperones, and captivating insights into partnerships between proteins and minerals have also been described. Very high resolution metal site structures and metalloprotein design will be increasingly important in order to leverage the wealth of native metalloprotein structures into a deep understanding of metal ion site specificity and activity. PMID:15582401

  7. Selective retention of basic compounds by metal aquo-ion affinity chromatography.

    PubMed

    Asakawa, Yoshiki; Yamamoto, Eiichi; Asakawa, Naoki

    2014-10-01

    A novel metal aquo-ion affinity chromatography has been developed for the analysis of basic compounds using heat-treated silica gel containing hydrated metal cations (metal aquo-ions) as the packing material. The packing materials of the metal aquo-ion affinity chromatography were prepared by the immobilization of a single metal component such as Fe(III), Al(III), Ag(I), and Ni(II) on silica gel followed by extensive heat treatment. The immobilized metals form aquo-ions to present cation-exchange ability for basic analytes and the cation-exchange ability for basic analytes depends on pKa of the immobilized metal species. In the present study, to evaluate the retention characteristics of metal aquo-ion affinity chromatography, the on-line solid-phase extraction of drugs was investigated. Obtained data clearly evidence the selective retention capability of metal aquo-ion affinity chromatography for basic analytes with sufficient capacity. PMID:25044622

  8. Impact of Protein-Metal Ion Interactions on the Crystallization of Silk Fibroin Protein

    NASA Astrophysics Data System (ADS)

    Hu, Xiao; Lu, Qiang; Kaplan, David; Cebe, Peggy

    2009-03-01

    Proteins can easily form bonds with a variety of metal ions, which provides many unique biological functions for the protein structures, and therefore controls the overall structural transformation of proteins. We use advanced thermal analysis methods such as temperature modulated differential scanning calorimetry and quasi-isothermal TMDSC, combined with Fourier transform infrared spectroscopy, and scanning electron microscopy, to investigate the protein-metallic ion interactions in Bombyx mori silk fibroin proteins. Silk samples were mixed with different metal ions (Ca^2+, K^+, Ma^2+, Na^+, Cu^2+, Mn^2+) with different mass ratios, and compared with the physical conditions in the silkworm gland. Results show that all metallic ions can directly affect the crystallization behavior and glass transition of silk fibroin. However, different ions tend to have different structural impact, including their role as plasticizer or anti-plasticizer. Detailed studies reveal important information allowing us better to understand the natural silk spinning and crystallization process.

  9. Alkali metal ion battery with bimetallic electrode

    SciTech Connect

    Boysen, Dane A; Bradwell, David J; Jiang, Kai; Kim, Hojong; Ortiz, Luis A; Sadoway, Donald R; Tomaszowska, Alina A; Wei, Weifeng; Wang, Kangli

    2015-04-07

    Electrochemical cells having molten electrodes having an alkali metal provide receipt and delivery of power by transporting atoms of the alkali metal between electrode environments of disparate chemical potentials through an electrochemical pathway comprising a salt of the alkali metal. The chemical potential of the alkali metal is decreased when combined with one or more non-alkali metals, thus producing a voltage between an electrode comprising the molten the alkali metal and the electrode comprising the combined alkali/non-alkali metals.

  10. A self-sputtering ion source: A new approach to quiescent metal ion beams

    SciTech Connect

    Oks, Efim M.; Anders, Andre

    2009-09-03

    A new metal ion source is presented based on sustained self-sputtering plasma in a magnetron discharge. Metals exhibiting high self-sputtering yield like Cu, Ag, Zn, and Bi can be used in a high-power impulse magnetron sputtering (HIPIMS) discharge such that the plasma almost exclusively contains singly charged metal ions of the target material. The plasma and extracted ion beam are quiescent. The ion beams consist mostly of singly charged ions with a space-charge limited current density which reached about 10 mA/cm2 at an extraction voltage of 45 kV and a first gap spacing of 12 mm.

  11. A self-sputtering ion source: A new approach to quiescent metal ion beams

    SciTech Connect

    Oks, Efim

    2010-02-15

    A new metal ion source is presented based on sustained self-sputtering plasma in a magnetron discharge. Metals exhibiting high self-sputtering yield such as Cu, Ag, Zn, and Bi can be used in a high-power impulse magnetron sputtering discharge such that the plasma almost exclusively contains singly charged metal ions of the target material. The plasma and extracted ion beam are quiescent. The ion beams consist mostly of singly charged ions with a space-charge limited current density which reached about 10 mA/cm{sup 2} at an extraction voltage of 45 kV and a first gap spacing of 12 mm.

  12. Determination of metal ion concentrations by SERS using 2,2'-bipyridyl complexes.

    PubMed

    Docherty, Julie; Mabbott, Samuel; Smith, W Ewen; Reglinski, John; Faulds, Karen; Davidson, Christine; Graham, Duncan

    2015-10-01

    Surface enhanced Raman scattering (SERS) can generate characteristic spectral "fingerprints" from metal complexes, thus providing the potential for the development of methods of analysis for the identification and quantitation of a range of metal ions in solution. The advantages include sensitivity and the use of one ligand for several metals without the need for a specific chromophore. Aqueous solutions of Fe(II), Ni(II), Zn(II), Cu(II), Cr(III) and Cd(II) in the presence of excess 2,2'-bipyridyl (bipy) were analysed using SERS. Specific marker bands enabled the identification of each metal ion and the limit of detection for each metal ion was estimated. Two of the ions, Zn(II) and Cu(II), could be detected below the World Health Organisation's (WHO) recommended limits for drinking water at levels of 0.22 and 0.6 mg L(-1), respectively. PMID:26312259

  13. Impregnated-electrode-type liquid metal ion source

    NASA Astrophysics Data System (ADS)

    Ishikawa, J.; Gotoh, Y.; Tsuji, H.; Takagi, T.

    We have developed an impregnated-electrode-type liquid metal ion source whose tip is a sintered-porous structure made of a refractory metal such as tungsten. By this structure the ratio of the liquid metal surface area facing the vacuum to the volume is low, which decreases useless metal evaporation from the surface. The maximum vapour pressure of the metal in operation for this ion source is 10 -1-10 0 Torr, which is 2-3 orders of magnitude higher than that for the needle type. Therefore, useful metal ions such as Ga +, Au +, Ag +, In +, Si 2+, Ge 2+, and Sb 2+ can be extracted from single element metals or alloys. The porous structure of the tip has also an effect on the positive control of the liquid metal flow rate to the tip head. Thus, a stable operation with a high current of a few hundreds of μA can be obtained together with a low current high brightness ion beam. Therefore, this ion source is suitable not only for microfocusing but also for a general use as a metal ion source.

  14. Structures and energetics of complexation of metal ions with ammonia, water, and benzene: A computational study.

    PubMed

    Sharma, Bhaskar; Neela, Y Indra; Narahari Sastry, G

    2016-04-30

    Quantum chemical calculations have been performed at CCSD(T)/def2-TZVP level to investigate the strength and nature of interactions of ammonia (NH3 ), water (H2 O), and benzene (C6 H6 ) with various metal ions and validated with the available experimental results. For all the considered metal ions, a preference for C6 H6 is observed for dicationic ions whereas the monocationic ions prefer to bind with NH3 . Density Functional Theory-Symmetry Adapted Perturbation Theory (DFT-SAPT) analysis has been employed at PBE0AC/def2-TZVP level on these complexes (closed shell), to understand the various energy terms contributing to binding energy (BE). The DFT-SAPT result shows that for the metal ion complexes with H2 O electrostatic component is the major contributor to the BE whereas, for C6 H6 complexes polarization component is dominant, except in the case of alkali metal ion complexes. However, in case of NH3 complexes, electrostatic component is dominant for s-block metal ions, whereas, for the d and p-block metal ion complexes both electrostatic and polarization components are important. The geometry (M(+) -N and M(+) -O distance for NH3 and H2 O complexes respectively, and cation-π distance for C6 H6 complexes) for the alkali and alkaline earth metal ion complexes increases down the group. Natural population analysis performed on NH3 , H2 O, and C6 H6 complexes shows that the charge transfer to metal ions is higher in case of C6 H6 complexes. PMID:26833683

  15. Reusable chelating resins concentrate metal ions from highly dilute solutions

    NASA Technical Reports Server (NTRS)

    Bauman, A. J.; Weetal, H. H.; Weliky, N.

    1966-01-01

    Column chromatographic method uses new metal chelating resins for recovering heavy-metal ions from highly dilute solutions. The absorbed heavy-metal cations may be removed from the chelating resins by acid or base washes. The resins are reusable after the washes are completed.

  16. Ligational behavior of Schiff bases towards transition metal ion and metalation effect on their antibacterial activity

    NASA Astrophysics Data System (ADS)

    Devi, Jai; Batra, Nisha; Malhotra, Rajesh

    2012-11-01

    New Schiff bases pyrazine-2-carboxylicacid (phenyl-pyridin-2-yl-methylene)-hydrazide (Hpch-bp) HL1 and pyrazine-2-carboxylicacid (pyridin-2-ylmethylene)-hydrazide (Hpch-pc) HL2 derived from condensation of pyrazine carboxylic hydrazide (Hpch) with 2-benzoyl pyridine (bp) or pyridine 2-carbaldehyde (pc) and their transition metal complexes of type ML(1-2)2 have been synthesized, where M = Mn(II), Co(II), Ni(II), Cu(II) and Zn(II). Characterization of ligands and their metal complexes was carried out by elemental analysis, conductimetric studies, magnetic susceptibility, spectroscopic techniques (IR, UV-VIS, NMR, ESR, Mass) and thermogravimetric analysis. The physico-chemical studies revealed octahedral geometry or distorted octahedral geometry around metal ion. These azomethine Schiff base ligands acted as tridentate ? coordinating through carbonyl, azomethine and pyridine nitrogen present in the ligand. The thermodynamic and thermal properties of the complexes have been investigated and it was observed on the basis of these studies that thermal stability of complexes follows the order Mn < Zn < Cu < Co < Ni. The ligands and their complexes were tested for in vitro antibacterial activity at different concentrations against bacteria viz. Gram positive Bacillus subtilis, Micrococcus luteus and Gram negative Pseudomonas aeruginosa, Pseudomonas mendocina. A marked enhancement in biocidal activity of the ligands under similar experimental conditions was observed as a consequence of coordination with metal ions. The trend of growth inhibition in the complexes was found to be in the order: Cu > Mn > Ni > Co > Zn.

  17. Blood metal ion testing is an effective screening tool to identify poorly performing metal-on-metal bearing surfaces

    PubMed Central

    Sidaginamale, R. P.; Joyce, T. J.; Lord, J. K.; Jefferson, R.; Blain, P. G.; Nargol, A. V. F.; Langton, D. J.

    2013-01-01

    Objectives The aims of this piece of work were to: 1) record the background concentrations of blood chromium (Cr) and cobalt (Co) concentrations in a large group of subjects; 2) to compare blood/serum Cr and Co concentrations with retrieved metal-on-metal (MoM) hip resurfacings; 3) to examine the distribution of Co and Cr in the serum and whole blood of patients with MoM hip arthroplasties; and 4) to further understand the partitioning of metal ions between the serum and whole blood fractions. Methods A total of 3042 blood samples donated to the local transfusion centre were analysed to record Co and Cr concentrations. Also, 91 hip resurfacing devices from patients who had given pre-revision blood/serum samples for metal ion analysis underwent volumetric wear assessment using a coordinate measuring machine. Linear regression analysis was carried out and receiver operating characteristic curves were constructed to assess the reliability of metal ions to identify abnormally wearing implants. The relationship between serum and whole blood concentrations of Cr and Co in 1048 patients was analysed using Bland-Altman charts. This relationship was further investigated in an in vitro study during which human blood was spiked with trivalent and hexavalent Cr, the serum then separated and the fractions analysed. Results Only one patient in the transfusion group was found to have a blood Co > 2 µg/l. Blood/Serum Cr and Co concentrations were reliable indicators of abnormal wear. Blood Co appeared to be the most useful clinical test, with a concentration of 4.5 µg/l showing sensitivity and specificity for the detection of abnormal wear of 94% and 95%, respectively. Generated metal ions tended to fill the serum compartment preferentially in vivo and this was replicated in the in vitro study when blood was spiked with trivalent Cr and bivalent Co. Conclusions Blood/serum metal ion concentrations are reliable indicators of abnormal wear processes. Important differences exist

  18. Catalysis using hydrous metal oxide ion exchanges

    DOEpatents

    Dosch, Robert G.; Stephens, Howard P.; Stohl, Frances V.

    1985-01-01

    In a process which is catalyzed by a catalyst comprising an active metal on a carrier, said metal being active as a catalyst for the process, an improvement is provided wherein the catalyst is a hydrous, alkali metal or alkaline earth metal titanate, zirconate, niobate or tantalate wherein alkali or alkaline earth metal cations have been exchanged with a catalytically effective amount of cations of said metal.

  19. Catalysis using hydrous metal oxide ion exchangers

    DOEpatents

    Dosch, R.G.; Stephens, H.P.; Stohl, F.V.

    1983-07-21

    In a process which is catalyzed by a catalyst comprising an active metal on a carrier, said metal being active as a catalyst for the process, an improvement is provided wherein the catalyst is a hydrous, alkali metal or alkaline earth metal titanate, zirconate, niobate or tantalate wherein alkali or alkaline earth metal cations have been exchanged with a catalytically effective amount of cations of said metal.

  20. Bioinorganic Chemistry of the Alkali Metal Ions.

    PubMed

    Kim, Youngsam; Nguyen, Thuy-Tien T; Churchill, David G

    2016-01-01

    The common Group 1 alkali metals are indeed ubiquitous on earth, in the oceans and in biological systems. In this introductory chapter, concepts involving aqueous chemistry and aspects of general coordination chemistry and oxygen atom donor chemistry are introduced. Also, there are nuclear isotopes of importance. A general discussion of Group 1 begins from the prevalence of the ions, and from a comparison of their ionic radii and ionization energies. While oxygen and water molecule binding have the most relevance to biology and in forming a detailed understanding between the elements, there is a wide range of basic chemistry that is potentially important, especially with respect to biological chelation and synthetic multi-dentate ligand design. The elements are widely distributed in life forms, in the terrestrial environment and in the oceans. The details about the workings in animal, as well as plant life are presented in this volume. Important biometallic aspects of human health and medicine are introduced as well. Seeing as the elements are widely present in biology, various particular endogenous molecules and enzymatic systems can be studied. Sodium and potassium are by far the most important and central elements for consideration. Aspects of lithium, rubidium, cesium and francium chemistry are also included; they help in making important comparisons related to the coordination chemistry of Na(+) and K(+). Physical methods are also introduced. PMID:26860297

  1. Sequence-selective metal ion binding to DNA oligonucleotides.

    PubMed

    Frøystein, N A; Davis, J T; Reid, B R; Sletten, E

    1993-07-01

    Metal ion titrations of several DNA oligonucleotides, 10 dodecamers and one decamer have been monitored by 1H NMR spectroscopy in order to elucidate metal ion binding patterns. Also, the effects of paramagnetic impurities on resonance linewidths and NOESY cross-peak intensities have been reversed by EDTA back-titration experiments. 1H 1D NMR spectra were recorded after successive additions of aliquots of different metal salts to oligonucleotide samples. Paramagnetic manganese(II) salts were used in most cases, but a few samples were also titrated with diamagnetic zinc(II). From this study, we conclude that there exists a sequence-selective metal ion binding pattern. The metal ions bind predominantly to 5'-G in the contexts 5'-GC and 5'-GA. The order of preference seems to be GG > or = GA > GT > > GC. No evidence of metal ion binding to 5'-G in 5'-GC steps or to non-G residues was found. The H6 or H8 resonances on preceding (5'-) bases were affected by the adjacent bound paramagnetic metal ion, but no effect was observed on the protons of the succeeding (3'-) base. The metal binding site in the duplexes is most likely at G-N7, as manifested by the pronounced paramagnetic line broadening or diamagnetic shift of the G-H8 signal. This sequence selectivity may be qualitatively explained by a sequence-dependent variation in the molecular electrostatic potentials of guanine residues (MEPs) along the oligonucleotide chain. PMID:8363924

  2. Does bearing size influence metal ion levels in large-head metal-on-metal total hip arthroplasty? A comparison of three total hip systems

    PubMed Central

    2014-01-01

    Background The purpose of the study was twofold: first, to determine whether there is a statistically significant difference in the metal ion levels among three different large-head metal-on-metal (MOM) total hip systems. The second objective was to assess whether position of the implanted prostheses, patient demographics or factors such as activity levels influence overall blood metal ion levels and whether there is a difference in the functional outcomes between the systems. Methods In a cross-sectional cohort study, three different metal-on-metal total hip systems were assessed: two monoblock heads, the Durom socket (Zimmer, Warsaw, IN, USA) and the Birmingham socket (Smith and Nephew, Memphis, TN, USA), and one modular metal-on-metal total hip system (Pinnacle, Depuy Orthopedics, Warsaw, IN, USA). Fifty-four patients were recruited, with a mean age of 59.7 years and a mean follow-up time of 41 months (12 to 60). Patients were evaluated clinically, radiologically and biochemically. Statistical analysis was performed on all collected data to assess any differences between the three groups in terms of overall blood metal ion levels and also to identify whether there was any other factor within the group demographics and outcomes that could influence the mean levels of Co and Cr. Results Although the functional outcome scores were similar in all three groups, the blood metal ion levels in the larger monoblock large heads (Durom, Birmingham sockets) were significantly raised compared with those of the Pinnacle group. In addition, the metal ion levels were not found to have a statistically significant relationship to the anteversion or abduction angles as measured on the radiographs. Conclusions When considering a MOM THR, the use of a monoblock large-head system leads to higher elevations in whole blood metal ions and offers no advantage over a smaller head modular system. PMID:24472283

  3. Metal ion adsorption at the ionic liquid-mica interface.

    PubMed

    McDonald, Samila; Elbourne, Aaron; Warr, Gregory G; Atkin, Rob

    2016-01-14

    Mica has been employed in many studies of ionic liquid (IL) interfaces on account of its atomic smoothness and well defined surface properties. However, until now it has been unclear whether ions dissolved in ILs can compete with the IL cation and adsorb to mica charge sites. In this work amplitude modulated atomic force microscopy (AM-AFM) has been used to probe metal ion adsorption at the interface of mica with propylammonium nitrate (PAN), a room temperature IL. Lithium, sodium, potassium, magnesium and calcium nitrate salts were added to PAN at a concentration of ∼60 mM. Aluminum nitrate was also investigated, but only at 5 mM because its solubility in PAN is much lower. The AM-AFM images obtained when the metal ions were present are strikingly different to that of pure PAN, indicating that the ions compete effectively with the propylammonium cation and adsorb to negatively charged sites on the mica surface despite their much lower concentration. This is a consequence of electrostatic attractions between the mica charge sites and the metal ions being significantly stronger than for the propylammonium cation; compared to the metal ions the propylammonium charged group is relatively constrained sterically. A distinct honeycomb pattern is noted for the PAN + Al(3+) system, less obviously for the divalent ions and not at all for monovalent ions. This difference is attributed to the strength of electrostatic interactions between metal ions and mica charge sites increasing with the ion charge, which means that divalent and (particularly) trivalent ions are located more precisely above the charged sites of the mica lattice. The images obtained allow important distinctions between metal ion adsorption at mica-water and mica-PAN interfaces to be made. PMID:26661934

  4. Separation of platinum group metal ions by Donnan dialysis

    SciTech Connect

    Brajter, K.; Slonawska, K.; Cox, J.A.

    1985-10-01

    Separations of metal ions on the basis of Donnan dialysis across anion-exchange membranes should be possible if the receiver electrolyte composition favors the formation of selected anionic complexes of the sample metal ions. Moreover, such a separation has the possibility of being better suited from some applications than batch or column experiments with anion-exchange resins. The above hypothesis are tested on the platinum-group metal ions, Pt(IV), Rh(III), Pd(II), Ir(III), and Ir(IV). 13 references, 4 tables.

  5. Progress in metal ion separation and preconcentration : an overview.

    SciTech Connect

    Bond, A. H.

    1998-05-19

    A brief historical perspective covering the most mature chemically-based metal ion separation methods is presented, as is a summary of the recommendations made in the 1987 National Research Council (NRC) report entitled ''Separation and Purification: Critical Needs and Opportunities''. A review of Progress in Metal Ion Separation and Preconcentration shows that advances are occurring in each area of need cited by the NRC. Following an explanation of the objectives and general organization of this book, the contents of each chapter are briefly summarized and some future research opportunities in metal ion separations are presented.

  6. An Animal Model Using Metallic Ions to Produce Autoimmune Nephritis.

    PubMed

    Ramírez-Sandoval, Roxana; Luévano-Rodríguez, Nayeli; Rodríguez-Rodríguez, Mayra; Pérez-Pérez, María Elena; Saldívar-Elias, Sergio; Gurrola-Carlos, Reinaldo; Avalos-Díaz, Esperanza; Bollain-y-Goytia, Juan José; Herrera-Esparza, Rafael

    2015-01-01

    Autoimmune nephritis triggered by metallic ions was assessed in a Long-Evans rat model. The parameters evaluated included antinuclear autoantibody production, kidney damage mediated by immune complexes detected by immunofluorescence, and renal function tested by retention of nitrogen waste products and proteinuria. To accomplish our goal, the animals were treated with the following ionic metals: HgCl2, CuSO4, AgNO3, and Pb(NO3)2. A group without ionic metals was used as the control. The results of the present investigation demonstrated that metallic ions triggered antinuclear antibody production in 60% of animals, some of them with anti-DNA specificity. Furthermore, all animals treated with heavy metals developed toxic glomerulonephritis with immune complex deposition along the mesangium and membranes. These phenomena were accompanied by proteinuria and increased concentrations of urea. Based on these results, we conclude that metallic ions may induce experimental autoimmune nephritis. PMID:26064998

  7. An Animal Model Using Metallic Ions to Produce Autoimmune Nephritis

    PubMed Central

    Ramírez-Sandoval, Roxana; Luévano-Rodríguez, Nayeli; Rodríguez-Rodríguez, Mayra; Pérez-Pérez, María Elena; Saldívar-Elias, Sergio; Gurrola-Carlos, Reinaldo; Avalos-Díaz, Esperanza; Bollain-y-Goytia, Juan José

    2015-01-01

    Autoimmune nephritis triggered by metallic ions was assessed in a Long-Evans rat model. The parameters evaluated included antinuclear autoantibody production, kidney damage mediated by immune complexes detected by immunofluorescence, and renal function tested by retention of nitrogen waste products and proteinuria. To accomplish our goal, the animals were treated with the following ionic metals: HgCl2, CuSO4, AgNO3, and Pb(NO3)2. A group without ionic metals was used as the control. The results of the present investigation demonstrated that metallic ions triggered antinuclear antibody production in 60% of animals, some of them with anti-DNA specificity. Furthermore, all animals treated with heavy metals developed toxic glomerulonephritis with immune complex deposition along the mesangium and membranes. These phenomena were accompanied by proteinuria and increased concentrations of urea. Based on these results, we conclude that metallic ions may induce experimental autoimmune nephritis. PMID:26064998

  8. Theory of oxidation/reduction-induced valence transformations of metal ion dopants in oxide crystals mediated by oxide-vacancy diffusion: II. Kinetic analysis

    NASA Astrophysics Data System (ADS)

    Sinder, M.; Burshtein, Z.; Pelleg, J.

    2014-04-01

    We consider theoretically valence transformations of doping metal ions in oxide crystals induced by oxidation and reduction obtained by changes in the ambient oxygen partial pressure. Three types of oxygen vacancies are assumed to mediate transformations: neutral, singly ionized, and doubly ionized. In the companion part I paper we provide thermodynamic analyses yielding concentration relations among the oxygen vacancy, metal ions, holes and electrons, as functions of the ambient oxygen pressure. In the present companion part II paper we provide time dependent concentration profiles of the various species and reaction rate profiles. The diffusion exhibits a complex behavior; under some conditions, it may be described by a constant diffusivity, and is symmetric with respect to oxidation and reduction. However, under a wide range of conditions, the ionic state changes are highly asymmetric with respect to oxidation and reduction. For example, in the case of a neutral vacancy, a very narrow reaction front may establish during reduction. In the inverse (oxidation) process, however, the different species' profiles are quite smooth.

  9. Rechargeable dual-metal-ion batteries for advanced energy storage.

    PubMed

    Yao, Hu-Rong; You, Ya; Yin, Ya-Xia; Wan, Li-Jun; Guo, Yu-Guo

    2016-04-14

    Energy storage devices are more important today than any time before in human history due to the increasing demand for clean and sustainable energy. Rechargeable batteries are emerging as the most efficient energy storage technology for a wide range of portable devices, grids and electronic vehicles. Future generations of batteries are required to have high gravimetric and volumetric energy, high power density, low price, long cycle life, high safety and low self-discharge properties. However, it is quite challenging to achieve the above properties simultaneously in state-of-the-art single metal ion batteries (e.g. Li-ion batteries, Na-ion batteries and Mg-ion batteries). In this contribution, hybrid-ion batteries in which various metal ions simultaneously engage to store energy are shown to provide a new perspective towards advanced energy storage: by connecting the respective advantages of different metal ion batteries they have recently attracted widespread attention due to their novel performances. The properties of hybrid-ion batteries are not simply the superposition of the performances of single ion batteries. To enable a distinct description, we only focus on dual-metal-ion batteries in this article, for which the design and the benefits are briefly discussed. We enumerate some new results about dual-metal-ion batteries and demonstrate the mechanism for improving performance based on knowledge from the literature and experiments. Although the search for hybrid-ion batteries is still at an early age, we believe that this strategy would be an excellent choice for breaking the inherent disadvantages of single ion batteries in the near future. PMID:26996438

  10. Metal ion levels: how can they help us?

    PubMed

    Griffin, William L

    2014-04-01

    Ion levels have been shown to reliably predict abnormal function of the bearing surface with increased wear, but ion levels should not be used alone as a trigger for when to proceed with revision surgery with metal-metal articulations. Risk stratification strategies help determine which patients should be monitored more closely with serial ion levels, cross-sectional imaging with a MARS MRI, or proceed on to revision. Based on the current data available, an ion level greater than 4.5 ppb (Cr or Co) may serve as a threshold for when abnormal wear is occurring, and is suggested as a trigger for a MARS MRI scan. PMID:24655610

  11. Characteristics of flows of energetic atoms reflected from metal targets during ion bombardment

    NASA Astrophysics Data System (ADS)

    Kuzmichev, A.; Perevertaylo, V.; Tsybulsky, L.; Volpian, O.

    2016-07-01

    Particle number and energy reflection coefficients for energetic neutralized gas ions (Ar and O atoms) backscattered from metal targets during ion bombardment have been calculated using TRIM code. The energy distributions of reflected atoms are computed, too, and their dependence on the primary ion energy and the angle of ion incidence is determined. The obtained data confirm the possibility of employing energetic atoms reflection for generation of high energy neutral beams and point out to take this phenomenon into account under analysis of the ion technology for coating deposition.

  12. Effects of metal ions on fibroblasts and spiral ganglion cells.

    PubMed

    Paasche, G; Ceschi, P; Löbler, M; Rösl, C; Gomes, P; Hahn, A; Rohm, H W; Sternberg, K; Lenarz, T; Schmitz, K-P; Barcikowski, S; Stöver, T

    2011-04-01

    Degeneration of spiral ganglion cells (SGC) after deafness and fibrous tissue growth around the electrode carrier after cochlear implantation are two of the major challenges in current cochlear implant research. Metal ions are known to possess antimicrobial and antiproliferative potential. The use of metal ions could therefore provide a way to reduce tissue growth around the electrode array after cochlear implantation. Here, we report on in vitro experiments with different concentrations of metal salts with antiproliferative and toxic effects on fibroblasts, PC-12 cells, and freshly isolated spiral ganglion cells, the target cells for electrical stimulation by a cochlear implant. Standard cell lines (NIH/3T3 and L-929 fibroblasts and PC-12 cells) and freshly isolated SGC were incubated with concentrations of metal ions between 0.3 μmol/liter and 10 mmol/liter for 48 hr. Cell survival was investigated by neutral red uptake, CellQuantiBlue assay, or counting of stained surviving neurons. Silver ions exhibited distinct thresholds for proliferating and confluent cells. For zinc ions, the effective concentration was lower for fibroblasts than for PC-12 cells. SGC showed comparable thresholds for reduced cell survival not only for silver and zinc ions but also for copper(II) ions, indicating that these ions might be promising for reducing tissue growth on the surface of CI electrode arrays. These effects were also observed when combinations of two of these ions were investigated. PMID:21312225

  13. Extracting metal ions with diphosphonic acid, or derivative thereof

    DOEpatents

    Horwitz, Earl P.; Gatrone, Ralph C.; Nash, Kenneth L.

    1994-01-01

    Thermodynamically-unstable complexing agents which are diphosphonic acids and diphosphonic acid derivatives (or sulphur containing analogs), like carboxyhydroxymethanediphosphonic acid and vinylidene-1,1-diphosphonic acid, are capable of complexing with metal ions, and especially metal ions in the II, III, IV, V and VI oxidation states, to form stable, water-soluble metal ion complexes in moderately alkaline to highly-acidic media. However, the complexing agents can be decomposed, under mild conditions, into non-organic compounds which, for many purposes are environmentally-nondamaging compounds thereby degrading the complex and releasing the metal ion for disposal or recovery. Uses for such complexing agents as well as methods for their manufacture are also described.

  14. Extracting metal ions with diphosphonic acid, or derivative thereof

    DOEpatents

    Horwitz, E.P.; Gatrone, R.C.; Nash, K.L.

    1994-07-26

    Thermodynamically-unstable complexing agents which are diphosphonic acids and diphosphonic acid derivatives (or sulfur containing analogs), like carboxyhydroxymethanediphosphonic acid and vinylidene-1,1-diphosphonic acid, are capable of complexing with metal ions, and especially metal ions in the II, III, IV, V and VI oxidation states, to form stable, water-soluble metal ion complexes in moderately alkaline to highly-acidic media. However, the complexing agents can be decomposed, under mild conditions, into non-organic compounds which, for many purposes are environmentally-nondamaging compounds thereby degrading the complex and releasing the metal ion for disposal or recovery. Uses for such complexing agents as well as methods for their manufacture are also described. 1 fig.

  15. Metallic glass as a temperature sensor during ion plating

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Spalvins, T.; Buckley, D. H.

    1984-01-01

    The temperature of the interface and/or a superficial layer of a substrate during ion plating was investigated using a metallic glass of the composition Fe67Co18B14Si1 as the substrate and as the temperature sensor. Transmission electron microscopy and diffraction studies determined the microstructure of the ion-plated gold film and the substrate. Results indicate that crystallization occurs not only in the film, but also in the substrate. The grain size of crystals formed during ion plating was 6 to 60 nm in the gold film and 8 to 100 nm in the substrate at a depth of 10 to 15 micrometers from the ion-plated interface. The temperature rise of the substrate during ion plating was approximately 500 C. Discontinuous changes in metallurgical microstructure, and physical, chemical, and mechanical properties during the amorphous to crystalline transition in metallic glasses make metallic glasses extremely useful materials for temperature sensor applications in coating processes.

  16. Metallic glass as a temperature sensor during ion plating

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Spalvins, T.; Buckley, D. H.

    1985-01-01

    The temperature of the interface and/or a superficial layer of a substrate during ion plating was investigated using a metallic glass of the composition Fe67Co18B14Si1 as the substrate and as the temperature sensor. Transmission electron microscopy and diffraction studies determined the microstructure of the ion-plated gold film and the substrate. Results indicate that crystallization occurs not only in the film, but also in the substrate. The grain size of crystals formed during ion plating was 6 to 60 nm in the gold film and 8 to 100 nm in the substrate at a depth of 10 to 15 micrometers from the ion-plated interface. The temperature rise of the substrate during ion plating was approximately 500 C. Discontinuous changes in metallurgical microstructure, and physical, chemical, and mechanical properties during the amorphous to crystalline transition in metallic glasses make metallic glasses extremely useful materials for temperature sensor applications in coating processes.

  17. Comparison of synovial fluid, urine, and serum ion levels in metal-on-metal total hip arthroplasty at a minimum follow-up of 18 years.

    PubMed

    Lass, Richard; Grübl, Alexander; Kolb, Alexander; Stelzeneder, David; Pilger, Alexander; Kubista, Bernd; Giurea, Alexander; Windhager, Reinhard

    2014-09-01

    Diagnosis of adverse reactions to metal debris in metal-on-metal hip arthroplasty is a multifactorial process. Systemic ion levels are just one factor in the evaluation and should not be relied upon solely to determine the need for revision surgery. Furthermore, the correlation between cobalt or chromium serum, urine, or synovial fluid levels and adverse local tissue reactions is still incompletely understood. The hypothesis was that elevated serum and urine metal-ion concentrations are associated with elevated local metal-ion concentrations in primary total hip arthroplasties (THA) and with failure of metal-on-metal articulations in the long-term. In our present study, we evaluated these concentrations in 105 cementless THA with metal-on-metal articulating surfaces with small head diameter at a minimum of 18 years postoperatively. Spearman correlation showed a high correlation between the joint fluid aspirate concentration of cobalt and chromium with the serum cobalt (r = 0.81) and chromium level (r = 0.77) in patients with the THA as the only source of metal-ions. In these patients serum metal-ion analysis is a valuable method for screening. In patients with more than one source of metal or renal insufficiency additional investigations, like joint aspirations are an important tool for evaluation of wear and adverse tissue reactions in metal-on-metal THA. PMID:24841922

  18. Predicting the relative toxicity of metal ions using ion characteristics: Microtox{reg_sign} bioluminescence assay

    SciTech Connect

    McCloskey, J.T.; Newman, M.C.; Clark, S.B.

    1996-10-01

    Quantitative structure-activity relationships have been used to predict the relative toxicity of organic compounds. Although not as common, ion characteristics have also proven useful for predicting the relative toxicity of metal ions. The purpose of this study was to determine if the relative toxicity of metal ions using the Microtox{reg_sign} bioassay was predictable using ion characteristics. Median effect concentrations (EC50s) were determined for 20 metals in a NaNO{sub 3} medium, which reflected freshwater speciation conditions, using the Microtox bacterial assay. The log of EC50 values was modeled using several ion characteristics, and Akaike`s Information Criterion was calculated to determine which ion characteristics provided the best fit. Whether modeling total ion or free ion EC50 values, the one variable which best modeled EC50s was the softness index, while a combination of {chi}{sub m}{sup 2}r ({chi}{sub m} = electronegativity, r = Pauling ionic radius) and {vert_bar}log K{sub OH}{vert_bar} was the best two-variable model. Other variables, including {Delta}E{sub 0} and {chi}{sub m}{sup 2}r (one-variable models) and (AN/{Delta}IP, {Delta}E{sub 0}) and ({chi}{sub m}{sup 2}r, Z{sup 2}/r) (two-variable models), also gave adequate fits. Modeling with speciated (free ion) versus unspeciated (total ion) EC50 values did not improve fits. Modeling mono-, di-, and trivalent metal ions separately improved the models. The authors conclude that ion characteristics can be used to predict the relative toxicity of metal ions whether in freshwater (NaNO{sub 3} medium) or saltwater (NaCl medium) speciation conditions and that this approach can be applied to metal ions varying widely in both valence and binding tendencies.

  19. An Engineered Palette of Metal Ion Quenchable Fluorescent Proteins

    PubMed Central

    Yu, Xiaozhen; Strub, Marie-Paule; Barnard, Travis J.; Noinaj, Nicholas; Piszczek, Grzegorz; Buchanan, Susan K.; Taraska, Justin W.

    2014-01-01

    Many fluorescent proteins have been created to act as genetically encoded biosensors. With these sensors, changes in fluorescence report on chemical states in living cells. Transition metal ions such as copper, nickel, and zinc are crucial in many physiological and pathophysiological pathways. Here, we engineered a spectral series of optimized transition metal ion-binding fluorescent proteins that respond to metals with large changes in fluorescence intensity. These proteins can act as metal biosensors or imaging probes whose fluorescence can be tuned by metals. Each protein is uniquely modulated by four different metals (Cu2+, Ni2+, Co2+, and Zn2+). Crystallography revealed the geometry and location of metal binding to the engineered sites. When attached to the extracellular terminal of a membrane protein VAMP2, dimeric pairs of the sensors could be used in cells as ratiometric probes for transition metal ions. Thus, these engineered fluorescent proteins act as sensitive transition metal ion-responsive genetically encoded probes that span the visible spectrum. PMID:24752441

  20. Smart textile device using ion polymer metal compound.

    PubMed

    Nakamura, Taro; Ihara, Tadashi

    2013-01-01

    We have developed a smart textile device that detects angular displacement of attached surface using ion polymer metal compound. The device was composed of ion polymer metal compound (IPMC) which was fabricated from Nafion resin by heat-press and chemical gold plating. The generated voltage from IPMC was measured as a function of bending angle. Fabricated IPMC device was weaved into a cotton cloth and multidirectional movements were detected. PMID:24109750

  1. Metal ion implantation for large scale surface modification

    SciTech Connect

    Brown, I.G.

    1992-10-01

    Intense energetic beams of metal ions can be produced by using a metal vapor vacuum arc as the plasma discharge from which the ion beam is formed. We have developed a number of ion sources of this kind and have built a metal ion implantation facility which can produce repetitively pulsed ion beams with mean ion energy up to several hundred key, pulsed beam current of more than an ampere, and time averaged current of several tens of milliamperes delivered onto a downstream target. We've also done some preliminary work on scaling up this technology to very large size. For example, a 50-cm diameter (2000 cm[sup 2]) set of beam formation electrodes was used to produce a pulsed titanium beam with ion current over 7 amperes at a mean ion energy of 100 key. Separately, a dc embodiment has been used to produce a dc titanium ion beam with current over 600 mA, power supply limited in this work, and up to 6 amperes of dc plasma ion current was maintained for over an hour. In a related program we've developed a plasma immersion method for applying thin metallic and compound films in which the added species is atomically mixed to the substrate. By adding a gas flow to the process, well-bonded compound films can also be formed; metallic films and multilayers as well as oxides and nitrides with mixed transition zones some hundreds of angstroms thick have been synthesized. Here we outline these parallel metal-plasma-based research programs and describe the hardware that we've developed and some of the surface modification research that we've done with it.

  2. Production of negative hydrogen ions on metal grids

    SciTech Connect

    Oohara, W.; Maetani, Y.; Takeda, Takashi; Takeda, Toshiaki; Yokoyama, H.; Kawata, K.

    2015-03-15

    Negative hydrogen ions are produced on a nickel grid with positive-ion irradiation. In order to investigate the production mechanism, a copper grid without the chemisorption of hydrogen atoms and positive helium ions without negative ionization are used for comparison. Positive hydrogen ions reflected on the metal surface obtain two electrons from the surface and become negatively ionized. It is found that the production yield of negative ions by desorption ionization of chemisorbed hydrogen atoms seems to be small, and the production is a minor mechanism.

  3. The Interchangeability of Plasma and Whole Blood Metal Ion Measurement in the Monitoring of Metal on Metal Hips

    PubMed Central

    Malek, Ibrahim A.; Rogers, Joanne; King, Amanda Christina; Clutton, Juliet; Winson, Daniel; John, Alun

    2015-01-01

    One hundred and twenty six paired samples of plasma and whole blood were measured with inductively coupled plasma mass spectrometry technique for metal ions analysis to determine a relationship between them. There was a significant difference between the mean plasma and whole blood concentrations of both cobalt (Co) and chromium (Cr) (p < 0.0001 for both Co and Cr). The mean ratio between plasma and whole blood Cr and Co was 1.56 (range: 0.39–3.85) and 1.54 (range: 0.64–18.26), respectively, but Bland and Altman analysis illustrated that this relationship was not universal throughout the range of concentrations. There was higher variability at high concentrations for both ions. We conclude that both these concentrations should not be used interchangeably and conversion factors are unreliable due to concentration dependent variability. PMID:26798516

  4. Implantation of nitrogen, carbon, and phosphorus ions into metals

    SciTech Connect

    Guseva, M.I.; Gordeeva, G.V.

    1987-01-01

    The application of ion implantation for alloying offers a unique opportunity to modify the chemical composition, phase constitution, and microstructure of the surface layers of metals. The authors studied ion implantation of nitrogen and carbon into the surface layers of metallic targets. The phase composition of the implanted layers obtained on the Kh18N10T stainless steel, the refractory molybdenum alloy TsM-6, niobium, and nickel was determined according to the conventional method of recording the x-ray diffraction pattern of the specimens using monochromatic FeK/sub alpha/-radiation on a DRON-2,0 diffractometer. The targets were bombarded at room temperature in an ILU-3 ion accelerator. The implantation of metalloid ions was also conducted with the targets being bombarded with 100-keV phosphorus ions and 40-keV carbon ions.

  5. Quantum ion-acoustic wave oscillations in metallic nanowires

    SciTech Connect

    Moradi, Afshin

    2015-05-15

    The low-frequency electrostatic waves in metallic nanowires are studied using the quantum hydrodynamic model, in which the electron and ion components of the system are regarded as a two-species quantum plasma system. The Poisson equation as well as appropriate quantum boundary conditions give the analytical expressions of dispersion relations of the surface and bulk quantum ion-acoustic wave oscillations.

  6. Metal ion adsorption to complexes of humic acid and metal oxides: Deviations from the additivity rule

    SciTech Connect

    Vermeer, A.W.P.; McCulloch, J.K.; Van Riemsdijk, W.H.; Koopal, L.K.

    1999-11-01

    The adsorption of cadmium ions to a mixture of Aldrich humic acid and hematite is investigated. The actual adsorption to the humic acid-hematite complex is compared with the sum of the cadmium ion adsorptivities to each of the isolated components. It is shown that the sum of the cadmium ion adsorptivities is not equal to the adsorption to the complex. In general, the adsorption of a specific metal ion to the complex can be understood and qualitatively predicted using the adsorptivities to each of the pure components and taking into account the effect of the pH on the interaction between humic acid and iron oxide on the metal ion adsorption. Due to the interaction between the negatively charged humic acid and the positively charged iron oxide, the adsorption of metal ions on the mineral oxide in the complex will increase as compared to that on the isolated oxide, whereas the adsorption to the humic acid will decrease as compared to that on the isolated humic acid. As a result, the overall adsorption of a specific metal ion to the complex will be smaller than predicted by the additivity rule when this metal ion has a more pronounced affinity for the humic acid than for the mineral oxide, whereas it will be larger than predicted by the additivity rule when the metal ion has a higher affinity for the oxide than for the humic acid.

  7. Ion chromatographic determination of transition metals in irradiated nuclear reactor surveillance samples.

    PubMed

    Louw, I

    1996-02-01

    The determination of transition metal ions in radioactive (+/-25 microCi/g) low-alloy steels (nuclear reactor surveillance samples) by ion chromatography (IC) is described. The analysis has been done directly without prior separation of the iron matrix. The eluted metal ions have been detected with a UV-visible spectrophotometric detector after post-column complexation with 4-(2-pyridylazo)resorcinol. The results are in a good agreement with the certified values for the standard reference material used. The method was applied to nuclear reactor surveillance samples for the determination of Cu, Mn, Co and Ni. PMID:15048428

  8. Structural Metals in the Group I Intron: A Ribozyme with a Multiple Metal Ion Core

    SciTech Connect

    Stahley,M.; Adams, P.; Wang, J.; Strobel, S.

    2007-01-01

    Metal ions play key roles in the folding and function for many structured RNAs, including group I introns. We determined the X-ray crystal structure of the Azoarcus bacterial group I intron in complex with its 5' and 3' exons. In addition to 222 nucleotides of RNA, the model includes 18 Mg2+ and K+ ions. Five of the metals bind within 12 Angstroms of the scissile phosphate and coordinate the majority of the oxygen atoms biochemically implicated in conserved metal-RNA interactions. The metals are buried deep within the structure and form a multiple metal ion core that is critical to group I intron structure and function. Eight metal ions bind in other conserved regions of the intron structure, and the remaining five interact with peripheral structural elements. Each of the 18 metals mediates tertiary interactions, facilitates local bends in the sugar-phosphate backbone or binds in the major groove of helices. The group I intron has a rich history of biochemical efforts aimed to identify RNA-metal ion interactions. The structural data are correlated to the biochemical results to further understand the role of metal ions in group I intron structure and function.

  9. Plasma spectroscopy of metal ions for hyper-electron cyclotron resonance ion source.

    PubMed

    Muto, Hideshi; Ohshiro, Yukimitsu; Yamaka, Shoichi; Watanabe, Shin-ichi; Oyaizu, Michihiro; Kubono, Shigeru; Yamaguchi, Hidetoshi; Kase, Masayuki; Hattori, Toshiyuki; Shimoura, Susumu

    2014-02-01

    In this research, the optical line spectra of metal ions from ECR plasma were observed using a grating monochromator with a photomultiplier. The light intensity of line spectrum from the ECR plasma had a strong correlation with ion beam intensity measured by a magnetic mass analyzer. This correlation is a significant information for the beam tuning process, because it allows to conduct the extraction of the desired metal ion species from the ECR plasma. Separation of ion species of the same charge to mass ratio with an electromagnetic mass analyzer is known to be an exceptionally complex process, but this research provides a new approach for its simplification. In this paper the grating monochromator method for metal ion beam tuning such as (40)Ca(12+), (56)Fe(15+), and (85)Rb(20+) of hyper-ECR ion source as an injector for RIKEN Azimuthal Varying Field cyclotron is described. PMID:24593484

  10. Comparative study of metal and non-metal ion implantation in polymers: Optical and electrical properties

    NASA Astrophysics Data System (ADS)

    Resta, V.; Quarta, G.; Farella, I.; Maruccio, L.; Cola, A.; Calcagnile, L.

    2014-07-01

    The implantation of 1 MeV metal (63Cu+, 107Ag+, 197Au+) and non-metal (4He+, 12C+) ions in a polycarbonate (PC) matrix has been studied in order to evaluate the role of ion species in the modification of optical and electrical properties of the polymer. When the ion fluence is above ∼1 × 1013 ions cm-2, the threshold for latent tracks overlapping is overcome and π-bonded carbon clusters grow and aggregate forming a network of conjugated Cdbnd C bonds. For fluences around 1 × 1017 ions cm-2, the aggregation phenomena induce the formation of amorphous carbon and/or graphite like structures. At the same time, nucleation of metal nanoparticles (NPs) from implanted species can take place when the supersaturation threshold is overcome. The optical absorption of the samples increases in the visible range and the optical band gap redshifts from 3.40 eV up to 0.70 eV mostly due to the carbonization process and the formation of C0x clusters and cluster aggregates. Specific structures in the extinction spectra are observed when metal ions are selected in contrast to the non-metal ion implanted PC, thus revealing the possible presence of noble metal based NPs interstitial to the C0x cluster network. The corresponding electrical resistance decreases much more when metal ions are implanted with at least a factor of 2 orders of magnitude difference than the non-metal ions based samples. An absolute value of ∼107 Ω/sq has been measured for implantation with metals at doses higher than 5 × 1016 ions cm-2, being 1017 Ω/sq the corresponding sheet resistance for pristine PC.

  11. Removal of metal ions from aqueous solution

    SciTech Connect

    Jackson, P.J.; Delhaize, E.; Robinson, N.J.; Unkefer, C.J.; Furlong, C.

    1990-03-20

    This patent describes a method of removing heavy metals from aqueous solution, a composition of matter used in effecting the removal, and apparatus used in effecting the removal. One or more of the polypeptides, poly ({gamma}-glutamylcysteinyl)glycines, is immobilized on an inert material in particulate form. Upon contact with an aqueous solution containing heavy metals, the polypeptides sequester the metals, removing them from the solution. There is selectivity of poly ({gamma}-glutamylcysteinyl)glycines having a particular number of monomer repeat units for particular metals. The polypeptides are easily regenerated by contact with a small amount of an organic acid, so that they can be used again to remove heavy metals from solution. This also results in the removal of the metals from the column in a concentrated form.

  12. Removal of metal ions from aqueous solution

    DOEpatents

    Jackson, Paul J.; Delhaize, Emmanuel; Robinson, Nigel J.; Unkefer, Clifford J.; Furlong, Clement

    1990-01-01

    A method of removing heavy metals from aqueous solution, a composition of matter used in effecting said removal, and apparatus used in effecting said removal. One or more of the polypeptides, poly (.gamma.-glutamylcysteinyl)glycines, is immobilized on an inert material in particulate form. Upon contact with an aqueous solution containing heavy metals, the polypeptides sequester the metals, removing them from the solution. There is selectivity of poly (.gamma.-glutamylcysteinyl)glycines having a particular number of monomer repeat units for particular metals. The polypeptides are easily regenerated by contact with a small amount of an organic acid, so that they can be used again to remove heavy metals from solution. This also results in the removal of the metals from the column in a concentrated form.

  13. Removal of metal ions from aqueous solution

    SciTech Connect

    Jackson, P.J.; Delhaize, E.; Robinson, N.J.; Unkefer, C.J.; Furlong, C.

    1988-08-26

    A method of removing heavy metals from aqueous solution, a composition of matter used in effecting said removal, and apparatus used in effecting said removal. One or more of the polypeptides, poly ({gamma}-glutamylcysteinyl)glycines, is immobilized on an inert material in particulate form. Upon contact with an aqueous solution containing heavy metals, the polypeptides sequester the metals, removing them from the solution. There is selectivity of poly ({gamma}-glutamylcysteinyl)glycines having a particular number of monomer repeat units for particular metals. The polypeptides are easily regenerated by contact with a small amount of an organic acid, so that they can be used again to remove heavy metals from solution. This also results in the removal of the metals from the column in a concentrated form.

  14. Removal of metal ions from aqueous solution

    SciTech Connect

    Jackson, P.J.; Delhaize, E.; Robinson, N.J.; Unkefer, C.J.; Furlong, C.

    1990-11-13

    A method is disclosed of removing heavy metals from aqueous solution, a composition of matter used in effecting said removal, and apparatus used in effecting said removal. One or more of the polypeptides, poly ([gamma]glutamylcysteinyl)glycines, is immobilized on an inert material in particulate form. Upon contact with an aqueous solution containing heavy metals, the polypeptides sequester the metals, removing them from the solution. There is selectivity of poly ([gamma]glutamylcysteinyl)glycines having a particular number of monomer repeat unit for particular metals. The polypeptides are easily regenerated by contact with a small amount of an organic acid, so that they can be used again to remove heavy metals from solution. This also results in the removal of the metals from the column in a concentrated form. 1 fig.

  15. Removal of metal ions from aqueous solution

    SciTech Connect

    Jackson, Paul J.; Delhaize, Emmanuel; Robinson, Nigel J.; Unkefer, Clifford J.; Furlong, Clement

    1990-11-13

    A method of removing heavy metals from aqueous solution, a composition of matter used in effecting said removal, and apparatus used in effecting said removal. One or more of the polypeptides, poly (.gamma.-glutamylcysteinyl)glycines, is immobilized on an inert material in particulate form. Upon contact with an aqueous solution containing heavy metals, the polypeptides sequester the metals, removing them from the solution. There is selectivity of poly (.gamma.-glutamylcysteinyl)glycines having a particular number of monomer repeat unit for particular metals. The polypeptides are easily regenerated by contact with a small amount of an organic acid, so that they can be used again to remove heayv metals from solution. This also results in the removal of the metals from the column in a concentrated form.

  16. In Vivo Metal Ion Imaging Using Fluorescent Sensors.

    PubMed

    Van de Bittner, Genevieve C; Hirayama, Tasuku

    2016-01-01

    In vivo imaging in living animals provides the ability to monitor alterations of signaling molecules, ions, and other biological components during various life stages and in disease. The data gained from in vivo imaging can be used for biological discovery or to determine elements of disease progression and can inform the development and translation of therapeutics. Herein, we present theories behind small-molecule, fluorescent, metal ion sensors as well as the methods for their successful application to in vivo metal ion imaging, including ex vivo validation. PMID:27283424

  17. A new paradigm of DNA synthesis: three-metal-ion catalysis.

    PubMed

    Yang, Wei; Weng, Peter J; Gao, Yang

    2016-01-01

    Enzyme catalysis has been studied for over a century. How it actually occurs has not been visualized until recently. By combining in crystallo reaction and X-ray diffraction analysis of reaction intermediates, we have obtained unprecedented atomic details of the DNA synthesis process. Contrary to the established theory that enzyme-substrate complexes and transition states have identical atomic composition and catalysis occurs by the two-metal-ion mechanism, we have discovered that an additional divalent cation has to be captured en route to product formation. Unlike the canonical two metal ions, which are coordinated by DNA polymerases, this third metal ion is free of enzyme coordination. Its location between the α- and β-phosphates of dNTP suggests that the third metal ion may drive the phosphoryltransfer from the leaving group opposite to the 3'-OH nucleophile. Experimental data indicate that binding of the third metal ion may be the rate-limiting step in DNA synthesis and the free energy associated with the metal-ion binding can overcome the activation barrier to the DNA synthesis reaction. PMID:27602203

  18. Investigation of trap properties in high-k/metal gate p-type metal-oxide-semiconductor field-effect-transistors with aluminum ion implantation using random telegraph noise analysis

    SciTech Connect

    Kao, Tsung-Hsien; Chang, Shoou-Jinn Fang, Yean-Kuen; Huang, Po-Chin; Wu, Chung-Yi; Wu, San-Lein

    2014-08-11

    In this study, the impact of aluminum ion implantation (Al I/I) on random telegraph noise (RTN) in high-k/metal gate (HK/MG) p-type metal-oxide-semiconductor field-effect-transistors (pMOSFETs) was investigated. The trap parameters of HK/MG pMOSFETs with Al I/I, such as trap energy level, capture time and emission time, activation energies for capture and emission, and trap location in the gate dielectric, were determined. The configuration coordinate diagram was also established. It was observed that the implanted Al could fill defects and form a thin Al{sub 2}O{sub 3} layer and thus increase the tunneling barrier height for holes. It was also observed that the trap position in the Al I/I samples was lower due to the Al I/I-induced dipole at the HfO{sub 2}/SiO{sub 2} interface.

  19. Neutralization by Metal Ions of the Toxicity of Sodium Selenide

    PubMed Central

    Dauplais, Marc; Lazard, Myriam; Blanquet, Sylvain; Plateau, Pierre

    2013-01-01

    Inert metal-selenide colloids are found in animals. They are believed to afford cross-protection against the toxicities of both metals and selenocompounds. Here, the toxicities of metal salt and sodium selenide mixtures were systematically studied using the death rate of Saccharomyces cerevisiae cells as an indicator. In parallel, the abilities of these mixtures to produce colloids were assessed. Studied metal cations could be classified in three groups: (i) metal ions that protect cells against selenium toxicity and form insoluble colloids with selenide (Ag+, Cd2+, Cu2+, Hg2+, Pb2+ and Zn2+), (ii) metal ions which protect cells by producing insoluble metal-selenide complexes and by catalyzing hydrogen selenide oxidation in the presence of dioxygen (Co2+ and Ni2+) and, finally, (iii) metal ions which do not afford protection and do not interact (Ca2+, Mg2+, Mn2+) or weakly interact (Fe2+) with selenide under the assayed conditions. When occurring, the insoluble complexes formed from divalent metal ions and selenide contained equimolar amounts of metal and selenium atoms. With the monovalent silver ion, the complex contained two silver atoms per selenium atom. Next, because selenides are compounds prone to oxidation, the stabilities of the above colloids were evaluated under oxidizing conditions. 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB), the reduction of which can be optically followed, was used to promote selenide oxidation. Complexes with cadmium, copper, lead, mercury or silver resisted dissolution by DTNB treatment over several hours. With nickel and cobalt, partial oxidation by DTNB occurred. On the other hand, when starting from ZnSe or FeSe complexes, full decompositions were obtained within a few tens of minutes. The above properties possibly explain why ZnSe and FeSe nanoparticles were not detected in animals exposed to selenocompounds. PMID:23342137

  20. The catalytic role of the M2 metal ion in PP2Cα

    NASA Astrophysics Data System (ADS)

    Pan, Chang; Tang, Jun-Yi; Xu, Yun-Fei; Xiao, Peng; Liu, Hong-Da; Wang, Hao-An; Wang, Wen-Bo; Meng, Fan-Guo; Yu, Xiao; Sun, Jin-Peng

    2015-02-01

    PP2C family phosphatases (the type 2C family of protein phosphatases; or metal-dependent phosphatase, PPM) constitute an important class of signaling enzymes that regulate many fundamental life activities. All PP2C family members have a conserved binuclear metal ion active center that is essential for their catalysis. However, the catalytic role of each metal ion during catalysis remains elusive. In this study, we discovered that mutations in the structurally buried D38 residue of PP2Cα (PPM1A) redefined the water-mediated hydrogen network in the active site and selectively disrupted M2 metal ion binding. Using the D38A and D38K mutations of PP2Cα as specific tools in combination with enzymology analysis, our results demonstrated that the M2 metal ion determines the rate-limiting step of substrate hydrolysis, participates in dianion substrate binding and stabilizes the leaving group after P-O bond cleavage. The newly characterized catalytic role of the M2 metal ion in this family not only provides insight into how the binuclear metal centers of the PP2C phosphatases are organized for efficient catalysis but also helps increase our understanding of the function and substrate specificity of PP2C family members.

  1. The catalytic role of the M2 metal ion in PP2Cα.

    PubMed

    Pan, Chang; Tang, Jun-yi; Xu, Yun-fei; Xiao, Peng; Liu, Hong-da; Wang, Hao-an; Wang, Wen-bo; Meng, Fan-guo; Yu, Xiao; Sun, Jin-peng

    2015-01-01

    PP2C family phosphatases (the type 2C family of protein phosphatases; or metal-dependent phosphatase, PPM) constitute an important class of signaling enzymes that regulate many fundamental life activities. All PP2C family members have a conserved binuclear metal ion active center that is essential for their catalysis. However, the catalytic role of each metal ion during catalysis remains elusive. In this study, we discovered that mutations in the structurally buried D38 residue of PP2Cα (PPM1A) redefined the water-mediated hydrogen network in the active site and selectively disrupted M2 metal ion binding. Using the D38A and D38K mutations of PP2Cα as specific tools in combination with enzymology analysis, our results demonstrated that the M2 metal ion determines the rate-limiting step of substrate hydrolysis, participates in dianion substrate binding and stabilizes the leaving group after P-O bond cleavage. The newly characterized catalytic role of the M2 metal ion in this family not only provides insight into how the binuclear metal centers of the PP2C phosphatases are organized for efficient catalysis but also helps increase our understanding of the function and substrate specificity of PP2C family members. PMID:25708299

  2. The Use of Divalent Metal Ions by Type II Topoisomerases

    PubMed Central

    Deweese, Joseph E.; Osheroff, Neil

    2010-01-01

    Type II topoisomerases are essential enzymes that regulate DNA under- and overwinding and remove knots and tangles from the genetic material. In order to carry out their critical physiological functions, these enzymes utilize a double-stranded DNA passage mechanism that requires them to generate a transient double-stranded break. Consequently, while necessary for cell survival, type II topoisomerases also have the capacity to fragment the genome. This feature of the prokaryotic and eukaryotic enzymes, respectively, is exploited to treat a variety of bacterial infections and cancers in humans. All type II topoisomerases require divalent metal ions for catalytic function. These metal ions function in two separate active sites and are necessary for the ATPase and DNA cleavage/ligation activities of the enzymes. ATPase activity is required for the strand passage process and utilizes the metal-dependent binding and hydrolysis of ATP to drive structural rearrangements in the protein. Both the DNA cleavage and ligation activities of type II topoisomerases require divalent metal ions and appear to utilize a novel variant of the canonical two-metal-ion phosphotransferase/hydrolase mechanism to facilitate these reactions. This article will focus primarily on eukaryotic type II topoisomerases and the roles of metal ions in the catalytic functions of these enzymes. PMID:20703329

  3. Metal ion implantation in inert polymers for strain gauge applications

    NASA Astrophysics Data System (ADS)

    Di Girolamo, Giovanni; Massaro, Marcello; Piscopiello, Emanuela; Tapfer, Leander

    2010-10-01

    Metal ion implantation in inert polymers may produce ultra-thin conducting films below the polymer surface. These subsurface films are promising structures for strain gauge applications. To this purpose, polycarbonate substrates were irradiated at room temperature with low-energy metal ions (Cu + and Ni +) and with fluences in the range between 1 × 10 16 and 1 × 10 17 ions/cm 2, in order to promote the precipitation of dispersed metal nanoparticles or the formation of a continuous thin film. The nanoparticle morphology and the microstructural properties of polymer nanocomposites were investigated by glancing-incidence X-ray diffraction and transmission electron microscopy (TEM) measurements. At lower fluences (<5 × 10 16 ions/cm 2) a spontaneous precipitation of spherical-shaped metal nanoparticles occurred below the polymer top-surface (˜50 nm), whereas at higher fluences the aggregation of metal nanoparticles produced the formation of a continuous polycrystalline nanofilm. Furthermore, a characteristic surface plasmon resonance peak was observed for nanocomposites produced at lower ion fluences, due to the presence of Cu nanoparticles. A reduced electrical resistance of the near-surface metal-polymer nanocomposite was measured. The variation of electrical conductivity as a function of the applied surface load was measured: we found a linear relationship and a very small hysteresis.

  4. The use of divalent metal ions by type II topoisomerases.

    PubMed

    Deweese, Joseph E; Osheroff, Neil

    2010-07-01

    Type II topoisomerases are essential enzymes that regulate DNA under- and overwinding and remove knots and tangles from the genetic material. In order to carry out their critical physiological functions, these enzymes utilize a double-stranded DNA passage mechanism that requires them to generate a transient double-stranded break. Consequently, while necessary for cell survival, type II topoisomerases also have the capacity to fragment the genome. This feature of the prokaryotic and eukaryotic enzymes, respectively, is exploited to treat a variety of bacterial infections and cancers in humans. All type II topoisomerases require divalent metal ions for catalytic function. These metal ions function in two separate active sites and are necessary for the ATPase and DNA cleavage/ligation activities of the enzymes. ATPase activity is required for the strand passage process and utilizes the metal-dependent binding and hydrolysis of ATP to drive structural rearrangements in the protein. Both the DNA cleavage and ligation activities of type II topoisomerases require divalent metal ions and appear to utilize a novel variant of the canonical two-metal-ion phosphotransferase/hydrolase mechanism to facilitate these reactions. This article will focus primarily on eukaryotic type II topoisomerases and the roles of metal ions in the catalytic functions of these enzymes. PMID:20703329

  5. Luminometric Label Array for Quantification and Identification of Metal Ions.

    PubMed

    Pihlasalo, Sari; Montoya Perez, Ileana; Hollo, Niklas; Hokkanen, Elina; Pahikkala, Tapio; Härmä, Harri

    2016-05-17

    Quantification and identification of metal ions has gained interest in drinking water and environmental analyses. We have developed a novel label array method for the quantification and identification of metal ions in drinking water. This simple ready-to-go method is based on the nonspecific interactions of multiple unstable lanthanide chelates and nonantenna ligands with sample leading to a luminescence signal profile, unique to the sample components. The limit of detection at ppb concentration level and average coefficient of variation of 10% were achieved with the developed label array. The identification of 15 different metal ions including different oxidation states Cr(3+)/Cr(6+), Cu(+)/Cu(2+), Fe(2+)/Fe(3+), and Pb(2+)/Pb(4+) was demonstrated. Moreover, a binary mixture of Cu(2+) and Fe(3+) and ternary mixture of Cd(2+), Ni(2+), and Pb(2+) were measured and individual ions were distinguished. PMID:27086705

  6. Ion beam induced nanosized Ag metal clusters in glass

    NASA Astrophysics Data System (ADS)

    Mahnke, H.-E.; Schattat, B.; Schubert-Bischoff, P.; Novakovic, N.

    2006-04-01

    Silver metal clusters have been formed in soda lime glass by high-energy heavy-ion irradiation at ISL. The metal cluster formation was detected with X-ray absorption spectroscopy (EXAFS) in fluorescence mode, and the shape of the clusters was imaged with transmission electron microscopy. While annealing in reducing atmosphere alone, leads to the formation of metal clusters in Ag-containing glasses, where the Ag was introduced by ion-exchange, such clusters are not very uniform in size and are randomly distributed over the Ag-containing glass volume. Irradiation with 600-MeV Au ions followed by annealing, however, results in clusters more uniform in size and arranged in chains parallel to the direction of the ion beam.

  7. Hall transport of divalent metal ion modified DNA lattices

    SciTech Connect

    Dugasani, Sreekantha Reddy; Lee, Keun Woo; Yoo, Sanghyun; Gnapareddy, Bramaramba; Bashar, Saima; Park, Sung Ha; Kim, Si Joon; Jung, Joohye; Jung, Tae Soo; Kim, Hyun Jae

    2015-06-29

    We investigate the Hall transport characteristics of double-crossover divalent metal ion (Cu{sup 2+}, Ni{sup 2+}, Zn{sup 2+}, and Co{sup 2+})-modified DNA (M-DNA) lattices grown on silica via substrate-assisted growth. The electronic characteristics of the M-DNA lattices are investigated by varying the concentration of the metal ions and then conducting Hall measurements, including resistivity, Hall mobility, carrier concentration, and magneto resistance. The tendency of the resistivity and Hall mobility was to initially decrease as the ion concentration increased, until reaching the saturation concentration (C{sub s}) of each metal ion, and then to increase as the ion concentration increased further. On the other hand, the carrier concentration revealed the opposite tendency as the resistivity and Hall mobility. The specific binding (≤C{sub s}) and the nonspecific aggregates (>C{sub s}) of the ions into the DNA lattices were significantly affected by the Hall characteristics. The numerical ranges of the Hall parameters revealed that the M-DNA lattices with metal ions had semiconductor-like characteristics. Consequently, the distinct characteristics of the electrical transport through M-DNA lattices will provide useful information on the practical use of such structures in physical devices and chemical sensors.

  8. Means for obtaining a metal ion beam from a heavy-ion cyclotron source

    DOEpatents

    Hudson, E.D.; Mallory, M.L.

    1975-08-01

    A description is given of a modification to a cyclotron ion source used in producing a high intensity metal ion beam. A small amount of an inert support gas maintains the usual plasma arc, except that it is necessary for the support gas to have a heavy mass, e.g., xenon or krypton as opposed to neon. A plate, fabricated from the metal (or anything that can be sputtered) to be ionized, is mounted on the back wall of the ion source arc chamber and is bombarded by returning energetic low-charged gas ions that fail to cross the initial accelerating gap between the ion source and the accelerating electrode. Some of the atoms that are dislodged from the plate by the returning gas ions become ionized and are extracted as a useful beam of heavy ions. (auth)

  9. Ligational behavior of Schiff bases towards transition metal ion and metalation effect on their antibacterial activity.

    PubMed

    Devi, Jai; Batra, Nisha; Malhotra, Rajesh

    2012-11-01

    New Schiff bases pyrazine-2-carboxylicacid (phenyl-pyridin-2-yl-methylene)-hydrazide (Hpch-bp) HL(1) and pyrazine-2-carboxylicacid (pyridin-2-ylmethylene)-hydrazide (Hpch-pc) HL(2) derived from condensation of pyrazine carboxylic hydrazide (Hpch) with 2-benzoyl pyridine (bp) or pyridine 2-carbaldehyde (pc) and their transition metal complexes of type ML((1-2)2) have been synthesized, where M=Mn(II), Co(II), Ni(II), Cu(II) and Zn(II). Characterization of ligands and their metal complexes was carried out by elemental analysis, conductimetric studies, magnetic susceptibility, spectroscopic techniques (IR, UV-VIS, NMR, ESR, Mass) and thermogravimetric analysis. The physico-chemical studies revealed octahedral geometry or distorted octahedral geometry around metal ion. These azomethine Schiff base ligands acted as tridentate coordinating through carbonyl, azomethine and pyridine nitrogen present in the ligand. The thermodynamic and thermal properties of the complexes have been investigated and it was observed on the basis of these studies that thermal stability of complexes follows the order Mnmetal ions. The trend of growth inhibition in the complexes was found to be in the order: Cu>Mn>Ni>Co>Zn. PMID:22813991

  10. Complexation-induced supramolecular assembly drives metal-ion extraction.

    PubMed

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

    2014-09-26

    Combining experiment with theory reveals the role of self-assembly and complexation in metal-ion transfer through the water-oil interface. The coordinating metal salt Eu(NO3)3 was extracted from water into oil by a lipophilic neutral amphiphile. Molecular dynamics simulations were coupled to experimental spectroscopic and X-ray scattering techniques to investigate how local coordination interactions between the metal ion and ligands in the organic phase combine with long-range interactions to produce spontaneous changes in the solvent microstructure. Extraction of the Eu(3+)-3(NO3(-)) ion pairs involves incorporation of the "hard" metal complex into the core of "soft" aggregates. This seeds the formation of reverse micelles that draw the water and "free" amphiphile into nanoscale hydrophilic domains. The reverse micelles interact through attractive van der Waals interactions and coalesce into rod-shaped polynuclear Eu(III) -containing aggregates with metal centers bridged by nitrate. These preorganized hydrophilic domains, containing high densities of O-donor ligands and anions, provide improved Eu(III) solvation environments that help drive interfacial transfer, as is reflected by the increasing Eu(III) partitioning ratios (oil/aqueous) despite the organic phase approaching saturation. For the first time, this multiscale approach links metal-ion coordination with nanoscale structure to reveal the free-energy balance that drives the phase transfer of neutral metal salts. PMID:25169678

  11. A vacuum spark ion source: High charge state metal ion beams

    NASA Astrophysics Data System (ADS)

    Yushkov, G. Yu.; Nikolaev, A. G.; Oks, E. M.; Frolova, V. P.

    2016-02-01

    High ion charge state is often important in ion beam physics, among other reasons for the very practical purpose that it leads to proportionately higher ion beam energy for fixed accelerating voltage. The ion charge state of metal ion beams can be increased by replacing a vacuum arc ion source by a vacuum spark ion source. Since the voltage between anode and cathode remains high in a spark discharge compared to the vacuum arc, higher metal ion charge states are generated which can then be extracted as an ion beam. The use of a spark of pulse duration less than 10 μs and with current up to 10 kA allows the production of ion beams with current of several amperes at a pulse repetition rate of up to 5 pps. We have demonstrated the formation of high charge state heavy ions (bismuth) of up to 15 + and a mean ion charge state of more than 10 +. The physics and techniques of our vacuum spark ion source are described.

  12. A vacuum spark ion source: High charge state metal ion beams.

    PubMed

    Yushkov, G Yu; Nikolaev, A G; Oks, E M; Frolova, V P

    2016-02-01

    High ion charge state is often important in ion beam physics, among other reasons for the very practical purpose that it leads to proportionately higher ion beam energy for fixed accelerating voltage. The ion charge state of metal ion beams can be increased by replacing a vacuum arc ion source by a vacuum spark ion source. Since the voltage between anode and cathode remains high in a spark discharge compared to the vacuum arc, higher metal ion charge states are generated which can then be extracted as an ion beam. The use of a spark of pulse duration less than 10 μs and with current up to 10 kA allows the production of ion beams with current of several amperes at a pulse repetition rate of up to 5 pps. We have demonstrated the formation of high charge state heavy ions (bismuth) of up to 15 + and a mean ion charge state of more than 10 +. The physics and techniques of our vacuum spark ion source are described. PMID:26931966

  13. Intercalation of Coordinatively Unsaturated Fe(III) Ion within Interpenetrated Metal-Organic Framework MOF-5.

    PubMed

    Holmberg, Rebecca J; Burns, Thomas; Greer, Samuel M; Kobera, Libor; Stoian, Sebastian A; Korobkov, Ilia; Hill, Stephen; Bryce, David L; Woo, Tom K; Murugesu, Muralee

    2016-06-01

    Coordinatively unsaturated Fe(III) metal sites were successfully incorporated into the iconic MOF-5 framework. This new structure, Fe(III) -iMOF-5, is the first example of an interpenetrated MOF linked through intercalated metal ions. Structural characterization was performed with single-crystal and powder XRD, followed by extensive analysis by spectroscopic methods and solid-state NMR, which reveals the paramagnetic ion through its interaction with the framework. EPR and Mössbauer spectroscopy confirmed that the intercalated ions were indeed Fe(III) , whereas DFT calculations were employed to ascertain the unique pentacoordinate architecture around the Fe(III) ion. Interestingly, this is also the first crystallographic evidence of pentacoordinate Zn(II) within the MOF-5 SBU. This new MOF structure displays the potential for metal-site addition as a framework connector, thus creating further opportunity for the innovative development of new MOF materials. PMID:27061210

  14. Metal ions potentiate microglia responsiveness to endotoxin.

    PubMed

    Rachmawati, Dessy; Peferoen, Laura A N; Vogel, Daphne Y S; Alsalem, Inás W A; Amor, Sandra; Bontkes, Hetty J; von Blomberg, B Mary E; Scheper, Rik J; van Hoogstraten, Ingrid M W

    2016-02-15

    Oral metal exposure has been associated with diverse adverse reactions, including neurotoxicity. We showed previously that dentally applied metals activate dendritic cells (MoDC) via TLR4 (Ni, Co, Pd) and TLR3 (Au). It is still unknown whether the low levels of dental metals reaching the brain can trigger local innate cells or prime them to become more responsive. Here we tested whether dentally applied metals (Cr, Fe, Co, Ni, Cu, Zn, Au, Hg) activate primary human microglia in vitro and, as a model, monocytic THP-1-cells, in high non-toxic as well as near-physiological concentrations. In addition the effects of 'near-physiological' metal exposure on endotoxin (LPS) responsiveness of these cells were evaluated. IL-8 and IL-6 production after 24h was used as read out. In high, non-toxic concentrations all transition metals except Cr induced IL-8 and IL-6 production in microglia, with Ni and Co providing the strongest stimulation. When using near-physiological doses (up to 10× the normal plasma concentration), only Zn and Cu induced significant IL-8 production. Of note, the latter metals also markedly potentiated LPS responsiveness of microglia and THP-1 cells. In conclusion, transition metals activate microglia similar to MoDCs. In near-physiological concentrations Zn and Cu are the most effective mediators of innate immune activation. A clear synergism between innate responses to Zn/Cu and LPS was observed, shedding new light on the possible relation between oral metal exposure and neurotoxicity. PMID:26857501

  15. Analytical strategies based on quantum dots for heavy metal ions detection

    NASA Astrophysics Data System (ADS)

    Vázquez-González, Margarita; Carrillo-Carrion, Carolina

    2014-10-01

    Heavy metal contamination is one of the major concerns to human health because these substances are toxic and retained by the ecological system. Therefore, in recent years, there has been a pressing need for fast and reliable methods for the analysis of heavy metal ions in environmental and biological samples. Quantum dots (QDs) have facilitated the development of sensitive sensors over the past decade, due to their unique photophysical properties, versatile surface chemistry and ligand binding ability, and the possibility of the encapsulation in different materials or attachment to different functional materials, while retaining their native luminescence property. This paper comments on different sensing strategies with QD for the most toxic heavy metal ions (i.e., cadmium, Cd2+; mercury, Hg and lead, Pb2+). Finally, the challenges and outlook for the QD-based sensors for heavy metals ions are discussed.

  16. Does Ion Release Differ Between Hip Resurfacing and Metal-on-metal THA?

    PubMed Central

    Moroni, Antonio; Cadossi, Matteo; Baldini, Nicola; Giannini, Sandro

    2008-01-01

    Modern metal-on-metal hip resurfacing was introduced as a bone-preserving method of joint reconstruction for young and active patients; however, the large diameter of the bearing surfaces is of concern for potential increased metal ion release. We hypothesized there were no differences in serum concentrations of chromium, cobalt, and molybdenum between patients who had metal-on-metal hip resurfacing (Group A; average head diameter, 48 mm; median followup, 24 months) and patients who had 28-mm metal-on-metal THA (Group B; median followup, 25 months). Serum concentrations also were compared with concentrations in healthy subjects. We identified no differences in ion levels between Groups A and B. A distinction was made according to gender. Women showed a higher chromium release in Group A whereas men had a higher cobalt release in Group B. Values obtained from Group A were higher than those of the control subjects. Our data suggest metal-on-metal bearings for THA should not be rejected because of concern regarding potential increased metal ion release; however, patients with elevated ion levels, even without loosening or toxicity, could be at higher risk and should be followed up periodically. Level of Evidence: Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence. PMID:18196364

  17. Colored thin films for specific metal ion detection.

    PubMed

    Schauer, Caroline L; Chen, Mu-San; Price, Ronald R; Schoen, Paul E; Ligler, Frances S

    2004-08-15

    This paper describes the investigation of chitosan and poly(allylamine) (PAH) for the creation of a multi-film, color-based dipstick for the detection of metal ions in solution. Thin, colored films of chitosan and PAH cross-linked with hexamethylene 1,6-di(aminocarboxysulfonate) (HDACS) are created where color is due to film thickness and optical interference effects. The films are investigated for their ability to selectively detect aqueous metal ions via changes in thickness and/or color. Chitosan-HDACS films were selective for Cr(VI) over all other metal ions tested including Cr(acac)3 and Cr(NO3)3 x 9H2O, and PAH-HDACS films were selective for Cu(II) and Cu(I) salts over all other metal ions tested. The irreversible, selective changes due to metal ion solutions were not caused by varying the pH. Potomac River water was also tested using the two films, with results indicating the presence of Cu(II) in the aqueous sample. PMID:15382871

  18. Metal ion coupled protein folding and allosteric motions

    NASA Astrophysics Data System (ADS)

    Wang, Wei

    2014-03-01

    Many proteins need the help of cofactors for their successful folding and functioning. Metal ions, i.e., Zn2+, Ca2+, and Mg2+ etc., are typical biological cofactors. Binding of metal ions can reshape the energy landscapes of proteins, thereby modifying the folding and allosteric motions. For example, such binding may make the intrinsically disordered proteins have funneled energy landscapes, consequently, ensures their spontaneous folding. In addition, the binding may activate certain biological processes by inducing related conformational changes of regulation proteins. However, how the local interactions involving the metal ion binding can induce the global conformational motions of proteins remains elusive. Investigating such question requires multiple models with different details, including quantum mechanics, atomistic models, and coarse grained models. In our recent work, we have been developing such multiscale methods which can reasonably model the metal ion binding induced charge transfer, protonation/deprotonation, and large conformational motions of proteins. With such multiscale model, we elucidated the zinc-binding induced folding mechanism of classical zinc finger and the calcium-binding induced dynamic symmetry breaking in the allosteric motions of calmodulin. In addition, we studied the coupling of folding, calcium binding and allosteric motions of calmodulin domains. In this talk, I will introduce the above progresses on the metal ion coupled protein folding and allosteric motions. We thank the finacial support from NSFC and the 973 project.

  19. Membranes Remove Metal Ions Fron Industrial Liquids

    NASA Technical Reports Server (NTRS)

    Hsu, W. P. L.; May, C.

    1983-01-01

    Use of membrane films affords convenient and economical alternative for removing and recovering metal cations present in low concentrations from large quantities of liquid solutions. Possible applications of membrane films include use in analytical chemistry for determination of small amounts of toxic metallic impurities in lakes, streams, and municipal effluents. Also suitable for use as absorber of certain pollutant gases and odors present in confined areas.

  20. Process for modifying the metal ion sorption capacity of a medium

    DOEpatents

    Lundquist, Susan H.

    2002-01-01

    A process for modifying a medium is disclosed that includes treating a medium having a metal ion sorption capacity with a solution that includes: A) an agent capable of forming a complex with metal ions; and B) ions selected from the group consisting of sodium ions, potassium ions, magnesium ions, and combinations thereof, to create a medium having an increased capacity to sorb metal ions relative to the untreated medium.

  1. Topographical analysis of regulatory and metal ion binding sites on glutamine synthetase from Escherichia coli: 13C and 31P nuclear magnetic resonance and fluorescence energy transfer study

    PubMed Central

    Villafranca, J. J.; Rhee, S. G.; Chock, P. B.

    1978-01-01

    The paramagnetic effect of Mn(II) on 13C and 31P nuclear magnetic resonance signals from the [2-13C]ATP adenylylated glutamine synthetase [L-glutamate:ammonia ligase (ADP-forming); EC 6.3.1.2] from Escherichia coli was measured. This effect permitted the determination of distances from the 2-C position and the phosphorus of covalently bound AMP to the two Mn(II) binding sites, n1 and n2. Binding of Mn(II) to the n1 site converts an inactive apo-enzyme to its active form, while the metal ion bound at n2 occupies the metal-nucleotide substrate site. The distances from Mn(II) at the n1 and n2 sites to phosphorus are ∼10 and ∼7 Å and to the 2-C position of the adenine ring are ∼12 and ∼11 Å, respectively. The fluorescence energy transfer method was used to determine distances between Co(II) at n1 and n2 and the adenylyl site. For this experiment the enzyme was adenylylated with ε-ATP. The distances between ε-adenine and Co(II) at n1 and n2 are ∼13 and ∼11 Å, respectively. Quantitation of the paramagnetic effect due to Co(II) on the 31P nuclear magnetic resonance signal yielded values of 8 and 6 Å for the distances between the phosphorus of the covalently bound AMP and the n1 and n2 sites, respectively. The results reveal that the covalent modification site is very close to the catalytic center of the enzyme. In this study both nuclear magnetic resonance and fluorescence energy transfer techniques have been used to determine distances between the same set of sites on an enzyme surface. PMID:26053

  2. Decreased fluidity of cell membranes causes a metal ion deficiency in recombinant Saccharomyces cerevisiae producing carotenoids.

    PubMed

    Liu, Peitong; Sun, Liang; Sun, Yuxia; Shang, Fei; Yan, Guoliang

    2016-04-01

    The genome-wide transcriptional responses of S. cerevisiae to heterologous carotenoid biosynthesis were investigated using DNA microarray analysis. The results show that the genes involved in metal ion transport were specifically up-regulated in the recombinant strain, and metal ions, including Cu(2+), Fe(2+), Mn(2+), and Mg(2+), were deficient in the recombinant strain compared to the ion content of the parent strain. The decrease in metal ions was ascribed to a decrease in cell membrane (CM) fluidity caused by lower levels of unsaturated fatty acids and ergosterol. This was confirmed by the observation that metal ion levels were restored when CM fluidity was increased by supplying linoleic acid. In addition, a 24.3 % increase in the β-carotene concentration was observed. Collectively, our results suggest that heterologous production of carotenoids in S. cerevisiae can induce cellular stress by rigidifying the CM, which can lead to a deficiency in metal ions. Due to the importance of CM fluidity in cellular physiology, maintaining normal CM fluidity might be a potential approach to improving carotenoid production in genetically engineered S. cerevisiae. PMID:26749524

  3. In situ secondary ion mass spectrometry analysis

    SciTech Connect

    Groenewold, G.S.; Applehans, A.D.; Ingram, J.C.; Delmore, J.E.; Dahl, D.A.

    1993-01-01

    The direct detection of tributyl phosphate (TBP) on rocks using molecular beam surface analysis [MBSA or in situ secondary ion mass spectrometry (SIMS)] is demonstrated. Quantities as low as 250 ng were detected on basalt and sandstone with little or no sample preparation. Detection of TBP on soil has proven to be more problematic and requires further study. Ethylenediaminetetraacetic acid (EDTA) is more difficult to detect because it is very reactive with surfaces of interest. Nevertheless, it is possible to detect EDTA if the acidity of the surface is controlled. The detection of EDTA-metal complexes is currently an open question, but evidence is presented for the detection of ions arising from a EDTA-lead complex. Carboxylic acids (i.e., citric, ascorbic, malic, succinic, malonic, and oxalic) give characteristic SIM spectra, but their detection on sample surfaces awaits evaluation.

  4. Theoretical study of metal noble-gas positive ions

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Partridge, Harry; Langhoff, Stephen R.

    1989-01-01

    Theoretical calculations have been performed to determine the spectroscopic constant for the ground and selected low-lying electronic states of the transition-metal noble-gas ions Var(+), FeAr(+), CoAr(+), CuHe(+), CuAr(+), and CuKr(+). Analogous calculations have been performed for the ground states of the alkali noble-gas ions LiAr(+), LiKr(+), NaAr(+), and KAr(+) and the alkaline-earth noble-gas ion MgAr(+) to contrast the difference in binding energies between the simple and transition-metal noble-gas ions. The binding energies increase with increasing polarizability of the noble-gas ions, as expected for a charge-induced dipole bonding mechanism. It is found that the spectroscopic constants of the X 1Sigma(+) states of the alkali noble-gas ions are well described at the self-consistent field level. In contrast, the binding energies of the transition-metal noble-gas ions are substantially increased by electron correlation.

  5. BODIPY-based fluorometric sensor array for the highly sensitive identification of heavy-metal ions.

    PubMed

    Niu, Li-Ya; Li, Hui; Feng, Liang; Guan, Ying-Shi; Chen, Yu-Zhe; Duan, Chun-Feng; Wu, Li-Zhu; Guan, Ya-Feng; Tung, Chen-Ho; Yang, Qing-Zheng

    2013-05-01

    A BODIPY(4,4-difluoro-4-bora-3a,4a-diaza-s-indacene)-based fluorometric sensor array has been developed for the highly sensitive detection of eight heavy-metal ions at micromolar concentration. The di-2-picolyamine (DPA) derivatives combine high affinities for a variety of heavy-metal ions with the capacity to perturb the fluorescence properties of BODIPY, making them perfectly suitable for the design of fluorometric sensor arrays for heavy-metal ions. 12 cross-reactive BODIPY fluorescent indicators provide facile identification of the heavy-metal ions using a standard chemometric approach (hierarchical clustering analysis); no misclassifications were found over 45 trials. Clear differentiation among heavy-metal ions as a function of concentration was also achieved, even down to 10(-7)M. A semi-quantitative interpolation of the heavy-metal concentration is obtained by comparing the total Euclidean distance of the measurement with a set of known concentrations in the library. PMID:23601979

  6. Localized ion milling of metallic and ceramic TEM specimens

    SciTech Connect

    Fisher, A.T.; Bentley, J.

    1986-01-01

    The utility of localized ion milling in the preparation of metallic and ceramic specimens for TEM and AEM is being evaluated from the standpoint of optimizing procedures and identifying limitations and milling characteristics. The equipment used was a Gatan model 645 precision ion milling system (PIMS). This device is a scanning ion beam instrument with which selected areas of a sample can be imaged by either secondary electron or secondary ion signals and selectively ion milled in a small region within the imaged area. The 1 to 10 keV ion beam can be focussed to a 2 ..mu..m spot. Specimens are thinned without removing them from the electron microscope specimen holder.

  7. Reducing hazardous heavy metal ions using mangium bark waste.

    PubMed

    Khabibi, Jauhar; Syafii, Wasrin; Sari, Rita Kartika

    2016-08-01

    The objective of this study was to evaluate the characteristics of mangium bark and its biosorbent ability to reduce heavy metal ions in standard solutions and wastewater and to assess changes in bark characteristics after heavy metal absorption. The experiments were conducted to determine heavy metal absorption from solutions of heavy metals alone and in mixtures as well as from wastewater. The results show that mangium bark can absorb heavy metals. Absorption percentages and capacities from single heavy metal solutions showed that Cu(2+) > Ni(2+) > Pb(2+) > Hg(2+), while those from mixture solutions showed that Hg(2+) > Cu(2+) > Pb(2+) > Ni(2+). Wastewater from gold mining only contained Cu, with an absorption percentage and capacity of 42.87 % and 0.75 mg/g, respectively. The highest absorption percentage and capacity of 92.77 % and 5.18 mg/g, respectively, were found for Hg(2+) in a mixture solution and Cu(2+) in single-metal solution. The Cu(2+) absorption process in a single-metal solution changed the biosorbent characteristics of the mangium bark, yielding a decreased crystalline fraction; changed transmittance on hydroxyl, carboxyl, and carbonyl groups; and increased the presence of Cu. In conclusion, mangium bark biosorbent can reduce hazardous heavy metal ions in both standard solutions and wastewater. PMID:27179811

  8. Low coefficient of thermal expansion polyimides containing metal ion additives

    NASA Technical Reports Server (NTRS)

    Stoakley, D. M.; St. Clair, A. K.

    1992-01-01

    Polyimides have become widely used as high performance polymers as a result of their excellent thermal stability and toughness. However, lowering their coefficient of thermal expansion (CTE) would increase their usefulness for aerospace and electronic applications where dimensional stability is a requirement. The incorporation of metal ion-containing additives into polyimides, resulting in significantly lowered CTE's, has been studied. Various metal ion additives have been added to both polyamic acid resins and soluble polyimide solutions in the concentration range of 4-23 weight percent. The incorporation of these metal ions has resulted in reductions in the CTE's of the control polyimides of 12 percent to over 100 percent depending on the choice of additive and its concentration.

  9. Ion exchange properties of novel hydrous metal oxide materials

    SciTech Connect

    Gardner, T.J.; McLaughlin, L.I.

    1996-12-31

    Hydrous metal oxide (HMO) materials are inorganic ion exchangers which have many desirable characteristics for catalyst support applications, including high cation exchange capacity, anion exchange capability, high surface area, ease of adjustment of acidity and basicity, bulk or thin film preparation, and similar chemistry for preparation of various transition metal oxides. Cation exchange capacity is engineered into these materials through the uniform incorporation of alkali cations via manipulation of alkoxide chemistry. Specific examples of the effects of Na stoichiometry and the addition of SiO{sub 2} to hydrous titanium oxide (HTO) on ion exchange behavior will be given. Acid titration and cationic metal precursor complex exchange will be used to characterize the ion exchange behavior of these novel materials.

  10. Low coefficient of thermal expansion polyimides containing metal ion additives

    SciTech Connect

    Stoakley, D.M.; St.Clair, A.K. )

    1992-07-01

    Polyimides have become widely used as high performance polymers as a result of their excellent thermal stability and toughness. However, lowering their coefficient of thermal expansion (CTE) would increase their usefulness for aerospace and electronic applications where dimensional stability is a requirement. The CTE's of conventional polyimides range from 30 to 60 ppm/C. Approaches that have been reported to lower their CTE's include linearizing the polymer molecular structure and orienting the polyimide film. This current study involves the incorporation of metal ion-containing additives into polyimides and has resulted in significantly lowered CTE's. Various metal ion additives have been added to both polyamic acid resins and soluble polyimide solutions in the concentration range of 4-23 weight percent. The incorporation of these metal ions has resulted in reductions in the CTE's of the control polyimides of 12% to over 100% depending on the choice of additive and its concentration.

  11. Metal plasma immersion ion implantation and deposition: A review

    SciTech Connect

    Anders, A.

    1996-09-01

    Metal Plasma Immersion Ion Implantation and Deposition (MePIIID) is a hybrid process combining cathodic arc deposition and plasma immersion ion implantation. The properties of metal plasma produced by vacuum arcs are reviewed and the consequences for MePIIID are discussed. Different version of MePIIID are described and compared with traditional methods of surface modification such as ion beam assisted deposition (IBAD). MePIIID is a very versatile approach because of the wide range of ion species and energies used. In one extreme case, films are deposited with ions in the energy range 20--50 eV, and at the other extreme, ions can be implanted with high energy (100 keV or more) without film deposition. Novel features of the technique include the use of improved macroparticle filters; the implementation of several plasma sources for multi-element surface modification; tuning of ion energy during implantation and deposition to tailor the substrate-film intermixed layer and structure of the growing film; simultaneous pulsing of the plasma potential (positive) and substrate bias (negative) with a modified Marx generator; and the use of high ion charge states.

  12. Comet encke: meteor metallic ion identification by mass spectrometer.

    PubMed

    Goldberg, R A; Aikin, A C

    1973-04-20

    Metal ions including 23(+) (Na(+)), 24(+) (Mg(+)) 28(+) (Si(+)), 39(+) (K(+)), 40(+) (Ca(+)), 45(+) (Sc(+)), 52(+) Cr(+)). 56(+) (Fe(+)), and 58(+) (Ni(+)) have been detected in the upper atmosphere during the period of the Beta Taurids meteor shower. The abundances of these ions relative to Si(+) show, agreement in most instances with abundances in chondrites. A notable exception is 45(+), which, if it is Sc(+), is 100 times more abundant than neutral scandium found in chondrites. PMID:17816288

  13. Comet Encke: Meteor metallic ion identification by mass spectrometer

    NASA Technical Reports Server (NTRS)

    Goldberg, R. A.; Aikin, A. C.

    1972-01-01

    Metal ions including Na-40(+), Mg-24(+), Si-28(+), K-39(+), Ca-40(+), Sc-45(+), Cr-52(+), Fe-56(+), and Ni-58(+) were detected in the upper atmosphere during the beta Taurids meteor shower. Abundances of these ions relative to Si(+) show agreement in most instances with chondrites. A notable exception is 45(+), which is Sc(+), is 100 times more abundant than neutral scandium found in chondrites.

  14. Two Divalent Metal Ions and Conformational Changes Play Roles in the Hammerhead Ribozyme Cleavage Reaction.

    PubMed

    Mir, Aamir; Chen, Ji; Robinson, Kyle; Lendy, Emma; Goodman, Jaclyn; Neau, David; Golden, Barbara L

    2015-10-20

    The hammerhead ribozyme is a self-cleaving RNA broadly dispersed across all kingdoms of life. Although it was the first of the small, nucleolytic ribozymes discovered, the mechanism by which it catalyzes its reaction remains elusive. The nucleobase of G12 is well positioned to be a general base, but it is unclear if or how this guanine base becomes activated for proton transfer. Metal ions have been implicated in the chemical mechanism, but no interactions between divalent metal ions and the cleavage site have been observed crystallographically. To better understand how this ribozyme functions, we have solved crystal structures of wild-type and G12A mutant ribozymes. We observe a pH-dependent conformational change centered around G12, consistent with this nucleotide becoming deprotonated. Crystallographic and kinetic analysis of the G12A mutant reveals a Zn(2+) specificity switch suggesting a direct interaction between a divalent metal ion and the purine at position 12. The metal ion specificity switch and the pH-rate profile of the G12A mutant suggest that the minor imino tautomer of A12 serves as the general base in the mutant ribozyme. We propose a model in which the hammerhead ribozyme rearranges prior to the cleavage reaction, positioning two divalent metal ions in the process. The first metal ion, positioned near G12, becomes directly coordinated to the O6 keto oxygen, to lower the pKa of the general base and organize the active site. The second metal ion, positioned near G10.1, bridges the N7 of G10.1 and the scissile phosphate and may participate directly in the cleavage reaction. PMID:26398724

  15. Adsorbent for metal ions and method of making and using

    DOEpatents

    White, Lloyd R.; Lundquist, Susan H.

    2000-01-01

    A method comprises the step of spray-drying a solution or slurry comprising (alkali metal or ammonium) (metal) hexacyanoferrate particles in a liquid, to provide monodisperse, substantially spherical particles in a yield of at least 70 percent of theoretical yield and having a particle size in the range of 1 to 500 micrometers, said particles being active towards Cs ions. The particles, which can be of a single salt or a combination of salts, can be used free flowing, in columns or beds, or entrapped in a nonwoven, fibrous web or matrix or a cast porous membrane, to selectively remove Cs ions from aqueous solutions.

  16. Adsorbent for metal ions and method of making and using

    DOEpatents

    White, L.R.; Lundquist, S.H.

    1999-08-10

    A method comprises the step of spray-drying a solution or slurry comprising (alkali metal or ammonium) (metal) hexacyanoferrate particles in a liquid, to provide monodisperse, substantially spherical particles in a yield of at least 70 percent of theoretical yield and having a particle size in the range of 1 to 500 micrometers, said particles being active towards Cs ions. The particles, which can be of a single salt or a combination of salts, can be used free flowing, in columns or beds, or entrapped in a nonwoven, fibrous web or matrix or a cast porous membrane, to selectively remove Cs ions from aqueous solutions. 2 figs.

  17. Adsorbent for metal ions and method of making and using

    DOEpatents

    White, Lloyd R.; Lundquist, Susan H.

    1999-01-01

    A method comprises the step of spray-drying a solution or slurry comprising (alkali metal or ammonium) (metal) hexacyanoferrate particles in a liquid, to provide monodisperse, substantially spherical particles in a yield of at least 70 percent of theoretical yield and having a particle size in the range of 1 to 500 micrometers, said particles being active towards Cs ions. The particles, which can be of a single salt or a combination of salts, can be used free flowing, in columns or beds, or entrapped in a nonwoven, fibrous web or matrix or a cast porous membrane, to selectively remove Cs ions from aqueous solutions.

  18. Smart responsive microcapsules capable of recognizing heavy metal ions.

    PubMed

    Pi, Shuo-Wei; Ju, Xiao-Jie; Wu, Han-Guang; Xie, Rui; Chu, Liang-Yin

    2010-09-15

    Smart responsive microcapsules capable of recognizing heavy metal ions are successfully prepared with oil-in-water-in-oil double emulsions as templates for polymerization in this study. The microcapsules are featured with thin poly(N-isopropylacrylamide-co-benzo-18-crown-6-acrylamide) (P(NIPAM-co-BCAm)) membranes, and they can selectively recognize special heavy metal ions such as barium(II) or lead(II) ions very well due to the "host-guest" complexation between the BCAm receptors and barium(II) or lead(II) ions. The stable BCAm/Ba(2+) or BCAm/Pb(2+) complexes in the P(NIPAM-co-BCAm) membrane cause a positive shift of the volume phase transition temperature of the crosslinked P(NIPAM-co-BCAm) hydrogel to a higher temperature, and the repulsion among the charged BCAm/Ba(2+) or BCAm/Pb(2+) complexes and the osmotic pressure within the P(NIPAM-co-BCAm) membranes result in the swelling of microcapsules. Induced by recognizing barium(II) or lead(II) ions, the prepared microcapsules with P(NIPAM-co-BCAm) membranes exhibit isothermal and significant swelling not only in outer and inner diameters but also in the membrane thickness. The proposed microcapsules in this study are highly attractive for developing smart sensors and/or carriers for detection and/or elimination of heavy metal ions. PMID:20656104

  19. Metal-Ion Additives Reduce Thermal Expansion Of Polyimides

    NASA Technical Reports Server (NTRS)

    Stoakley, Diane M.; St. Clair, Anne K.; Emerson, Burt R., Jr.; Willis, George L.

    1994-01-01

    Polyimides widely used as high-performance polymers because of their excellent thermal stability and toughness. However, their coefficients of thermal expansion (CTE's) greater than those of metals, ceramics, and glasses. Decreasing CTE's of polyimides increase usefulness for aerospace and electronics applications in which dimensional stability required. Additives containing metal ions reduce coefficients of thermal expansion of polyimides. Reductions range from 11 to over 100 percent.

  20. Existence of efficient divalent metal ion-catalyzed and inefficient divalent metal ion-independent channels in reactions catalyzed by a hammerhead ribozyme

    PubMed Central

    Zhou, Jing-Min; Zhou, De-Min; Takagi, Yasuomi; Kasai, Yasuhiro; Inoue, Atsushi; Baba, Tadashi; Taira, Kazunari

    2002-01-01

    The hammerhead ribozyme is generally accepted as a well characterized metalloenzyme. However, the precise nature of the interactions of the RNA with metal ions remains to be fully defined. Examination of metal ion-catalyzed hammerhead reactions at limited concentrations of metal ions is useful for evaluation of the role of metal ions, as demonstrated in this study. At concentrations of Mn2+ ions from 0.3 to 3 mM, addition of the ribozyme to the reaction mixture under single-turnover conditions enhances the reaction with the product reaching a fixed maximum level. Further addition of the ribozyme inhibits the reaction, demonstrating that a certain number of divalent metal ions is required for proper folding and also for catalysis. At extremely high concentrations, monovalent ions, such as Na+ ions, can also serve as cofactors in hammerhead ribozyme-catalyzed reactions. However, the catalytic efficiency of monovalent ions is extremely low and, thus, high concentrations are required. Furthermore, addition of monovalent ions to divalent metal ion-catalyzed hammerhead reactions inhibits the divalent metal ion-catalyzed reactions, suggesting that the more desirable divalent metal ion–ribozyme complexes are converted to less desirable monovalent metal ion–ribozyme complexes via removal of divalent metal ions, which serve as a structural support in the ribozyme complex. Even though two channels appear to exist, namely an efficient divalent metal ion-catalyzed channel and an inefficient monovalent metal ion-catalyzed channel, it is clear that, under physiological conditions, hammerhead ribozymes are metalloenzymes that act via the significantly more efficient divalent metal ion-dependent channel. Moreover, the observed kinetic data are consistent with Lilley’s and DeRose’s two-phase folding model that was based on ground state structure analyses. PMID:12034824

  1. Photoluminescence properties of Jahn-Teller transition-metal ions

    NASA Astrophysics Data System (ADS)

    Sanz-Ortiz, Marta N.; Rodríguez, Fernando

    2009-09-01

    This work investigates the influence of electron-phonon coupling associated with E ⊗e and T ⊗e Jahn-Teller (JT) effect in different transition-metal (TM) ions on de-excitation phenomena through nonradiative multiphonon relaxation, i.e., photoluminescence (PL) quenching. We developed a configurational curve model which is able to predict from the absorption spectrum whether a given JT-TM ion is PL or quenched. The prediction is made on the basis of an adapted Dexter-Klick-Russell parameter for JT systems, defined in terms of spectroscopic parameters through ΛJT=αΔeabs/Eabs, where Δeabs refers to the splitting of the parent octahedral Eg states by the JT distortion in E ⊗e (α =3/4) or T ⊗e (α =1/4), and Eabs is the energy of the first absorption band involving electronic transition between Eg and T2g. We show that PL in any JT-TM ion occurs whenever ΛJT<0.1 or is quenched if ΛJT>0.2. This result is noteworthy since it allows us to establish structural requirements for the JT-TM ion and the host crystal to be PL. Although PL properties of materials containing TM ions depend on a variety of structural factors such as the electronic configuration, the site symmetry, and the crystal field produced by neighboring atoms, the present model achieves this goal through a simple spectroscopic parameter: ΛJT. In this work we correlated the PL properties of different sixfold-coordinated JT systems such as Ti3+, Cu2+, Mn3+, Cr2+, Fe2+, Co3+, and Ni3+ in halides and oxides with ΛJT obtained from their respective absorption spectra. From this analysis we conclude that depending on the nature of the JT coupling and its strength, PL is either strongly favored or quenched in T ⊗e while it is mostly quenched in E ⊗e systems due to the larger JT distortion.

  2. How do energetic ions damage metallic surfaces?

    SciTech Connect

    Osetskiy, Yury N.; Calder, Andrew F.; Stoller, Roger E.

    2015-02-20

    Surface modification under bombardment by energetic ions observed under different conditions in structural and functional materials and can be either unavoidable effect of the conditions or targeted modification to enhance materials properties. Understanding basic mechanisms is necessary for predicting properties changes. The mechanisms activated during ion irradiation are of atomic scale and atomic scale modeling is the most suitable tool to study these processes. In this paper we present results of an extensive simulation program aimed at developing an understanding of primary surface damage in iron by energetic particles. We simulated 25 keV self-ion bombardment of Fe thin films with (100) and (110) surfaces at room temperature. A large number of simulations, ~400, were carried out allow a statistically significant treatment of the results. The particular mechanism of surface damage depends on how the destructive supersonic shock wave generated by the displacement cascade interacts with the free surface. Three basic scenarios were observed, with the limiting cases being damage created far below the surface with little or no impact on the surface itself, and extensive direct surface damage on the timescale of a few picoseconds. In some instances, formation of large <100> vacancy loops beneath the free surface was observed, which may explain some earlier experimental observations.

  3. How do energetic ions damage metallic surfaces?

    DOE PAGESBeta

    Osetskiy, Yury N.; Calder, Andrew F.; Stoller, Roger E.

    2015-02-20

    Surface modification under bombardment by energetic ions observed under different conditions in structural and functional materials and can be either unavoidable effect of the conditions or targeted modification to enhance materials properties. Understanding basic mechanisms is necessary for predicting properties changes. The mechanisms activated during ion irradiation are of atomic scale and atomic scale modeling is the most suitable tool to study these processes. In this paper we present results of an extensive simulation program aimed at developing an understanding of primary surface damage in iron by energetic particles. We simulated 25 keV self-ion bombardment of Fe thin films withmore » (100) and (110) surfaces at room temperature. A large number of simulations, ~400, were carried out allow a statistically significant treatment of the results. The particular mechanism of surface damage depends on how the destructive supersonic shock wave generated by the displacement cascade interacts with the free surface. Three basic scenarios were observed, with the limiting cases being damage created far below the surface with little or no impact on the surface itself, and extensive direct surface damage on the timescale of a few picoseconds. In some instances, formation of large <100> vacancy loops beneath the free surface was observed, which may explain some earlier experimental observations.« less

  4. Removal and recovery of toxic metal ions from aqueous waste sites using polymer pendant ligands

    SciTech Connect

    Fish, D.

    1996-10-01

    The purpose of this project is to investigate the use of polymer pendant ligand technology to remove and recover toxic metal ions from DOE aqueous waste sites. Polymer pendant lgiands are organic ligands, anchored to crosslinked, modified divinylbenzene-polystyrene beads, that can selectively complex metal ions. The metal ion removal step usually occurs through a complexation or ion exchange phenomena, thus recovery of the metal ions and reuse of the beads is readily accomplished.

  5. Metal ion effects on enolase activity

    SciTech Connect

    Lee, M.E.; Nowak, T.

    1986-05-01

    Most metal binding studies with yeast enolase suggest that two metals per monomer are required for catalytic activity. The functions of metal I and metal II have not been unequivocally defined. In a series of kinetic experiments where the concentration of MgII is kept constant at subsaturating levels (1mM), the addition of MnII or of ZnII gives a hyperbolic decrease in activity. The final velocity of these mixed metal systems is the same velocity obtained with either only MnII or ZnII respectively. The concentration of MnII (40 ..mu..M) or of Zn (2..mu..M) which gives half maximal effect in the presence of (1mM) MgII is approximately the same as the Km' value for MnII (9..mu..M) or ZnII (3..mu..M) respectively. Direct binding of MnII to enolase in the absence and presence of MgII shows that MnII and MgII compete for the same metal site on enolase. In the presence of 2-phosphoglycerate (2-PGA) and MgII, only a single site is occupied by MnII. Results suggest MnII at site I and MgII at site II. PRR and high resolution /sup 1/H and /sup 31/P NMR studies of enzyme-ligand complexes containing MnII and MgII and MnII are consistent with this model. /sub 31/P measurements allow a measure of the equilibrium constant (0.36) for enolase. Saturation transfer measurements yield net rate constants (k/sub f/ = 0.49s/sup -1/; k/sub r/ = 1.3s/sup -1/) for the overall reaction. These values are smaller than k/sub cat/ (38s/sup -1/) measured under analogous conditions. The cation at site I appears to determine catalytic activity.

  6. DUHOCAMIS: A dual hollow cathode ion source for metal ion beams

    SciTech Connect

    Zhao, W. J.; Mueller, M. W. O.; Janik, J.; Liu, K. X.; Ren, X. T.

    2008-02-15

    In this paper we describe a novel ion source named DUHOCAMIS for multiply charged metal ion beams. This ion source is derived from the hot cathode Penning ion gauge ion source (JINR, Dubna, 1957). A notable characteristic is the modified Penning geometry in the form of a hollow sputter electrode, coaxially positioned in a compact bottle-magnetic field along the central magnetic line of force. The interaction of the discharge geometry with the inhomogeneous but symmetrical magnetic field enables this device to be operated as hollow cathode discharge and Penning discharge as well. The main features of the ion source are the very high metal ion efficiency (up to 25%), good operational reproducibility, flexible and efficient operations for low charged as well as highly charged ions, compact setup, and easy maintenance. For light ions, e.g., up to titanium, well-collimated beams in the range of several tens of milliamperes of pulsed ion current (1 ms, 10/s) have been reliably performed in long time runs.

  7. DUHOCAMIS: a dual hollow cathode ion source for metal ion beams.

    PubMed

    Zhao, W J; Müller, M W O; Janik, J; Liu, K X; Ren, X T

    2008-02-01

    In this paper we describe a novel ion source named DUHOCAMIS for multiply charged metal ion beams. This ion source is derived from the hot cathode Penning ion gauge ion source (JINR, Dubna, 1957). A notable characteristic is the modified Penning geometry in the form of a hollow sputter electrode, coaxially positioned in a compact bottle-magnetic field along the central magnetic line of force. The interaction of the discharge geometry with the inhomogeneous but symmetrical magnetic field enables this device to be operated as hollow cathode discharge and Penning discharge as well. The main features of the ion source are the very high metal ion efficiency (up to 25%), good operational reproducibility, flexible and efficient operations for low charged as well as highly charged ions, compact setup, and easy maintenance. For light ions, e.g., up to titanium, well-collimated beams in the range of several tens of milliamperes of pulsed ion current (1 ms, 10/s) have been reliably performed in long time runs. PMID:18315181

  8. Sensing Metal Ions with DNA Building Blocks: Fluorescent Pyridobenzimidazole Nucleosides

    PubMed Central

    Kim, Su Jeong; Kool, Eric T.

    2008-01-01

    We describe novel fluorescent N-deoxyribosides (1 and 2) having 2-pyrido-2-benzimidazole and 2-quino-2-benzimidazole as aglycones. The compounds were prepared from the previously unknown heterocyclic precursors and Hoffer’s chlorosugar, yielding alpha anomers as the chief products. X-ray crystal structures confirmed the geometry, and showed that the pyridine and benzimidazole ring systems deviated from coplanarity in the solid state by 154° and 140°, respectively. In methanol the compounds 1 and 2 had absorption maxima at 360 and 370 nm respectively, and emission maxima at 494 and 539 nm. Experiments revealed varied fluorescence responses of the nucleosides to a panel of seventeen monovalent, divalent and trivalent metal ions in methanol. One or both of the nucleosides showed significant changes with ten of the metal ions. The most pronounced spectral changes for ligand-nucleoside 1 included red shifts in fluorescence (Au+, Au3+), strong quenching (Cu2+, Ni2+, Pt2+), and in substantial enhancements in emission intensity coupled with redshifts (Ag+, Cd2+, Zn2+). The greatest spectral changes for ligand-nucleoside 2 included a redshift in fluorescence (Ag+), a blueshift (Cd2+), strong quenching (Pd2+, Pt2+), and in substantial enhancements in emission intensity coupled with a blueshift (Zn2+). The compounds could be readily incorporated into oligodeoxynucleotides, where an initial study revealed that they retained sensitivity to metal ions in aqueous solution, and demonstrated possible cooperative sensing behavior with several ions. The two free nucleosides alone can act as differential sensors for at multiple metal ions, and they are potentially useful monomers for contributing metal ion sensing capability to DNAs. PMID:16669686

  9. Metallic ions in cometary comae and plasma tails

    NASA Astrophysics Data System (ADS)

    Ip, W.-H.; Axford, W. I.

    1986-06-01

    A surprising result of the International Cometary Explorer (ICE) observations of the comet Giacobini-Zinner was the detection of ions of mass 23-24 AMU with a relatively high abundance. According to the experiments, these ions may be either Na(+) or C2(+), if not both. It is suggested here that the detected ions may indeed be in part Na(+) and/or Mg(+), and that these and other metallic ions, especially Si(+) and Fe(+), may be an important component of the cometary ionosphere and central plasma tail. The reasons are similar in principle to those which account for the prevalence of such ions in sporadic E layers in the terrestrial ionosphere, notably the comparatively short timescales for ionization of their neutral parent atoms and the large difference between the rates of dissociative and radiative recombination.

  10. Mechanism of Metal Ion Activation of the Diphtheria Toxin Repressor DtxR

    NASA Astrophysics Data System (ADS)

    D'Aquino, J. Alejandro; Ringe, Dagmar

    2006-08-01

    The diphtheria toxin repressor, DtxR, is a metal ion-activated transcriptional regulator that has been linked to the virulence of Corynebacterium diphtheriae. Structure determination has shown that there are two metal ion binding sites per repressor monomer, and site-directed mutagenesis has demonstrated that binding site 2 (primary) is essential for recognition of the target DNA repressor, leaving the role of binding site 1 (ancillary) unclear (1 - 3). Calorimetric techniques have demonstrated that while binding site 1 (ancillary) has high affinity for metal ion with a binding constant of 2 × 10-7, binding site 2 (primary) is a low affinity binding site with a binding constant of 6.3 × 10-4. These two binding sites act independently and their contribution can be easily dissected by traditional mutational analysis. Our results clearly demonstrate that binding site 1 (ancillary) is the first one to be occupied during metal ion activation, playing a critical role in stabilization of the repressor. In addition, structural data obtained for the mutants Ni-DtxR(H79A,C102D), reported here and the previously reported DtxR(H79A) (4) has allowed us to propose a mechanism of metal ion activation for DtxR.

  11. Formation of Metal-Related Ions in Matrix-Assisted Laser Desorption Ionization.

    PubMed

    Lee, Chuping; Lu, I-Chung; Hsu, Hsu Chen; Lin, Hou-Yu; Liang, Sheng-Ping; Lee, Yuan-Tseh; Ni, Chi-Kung

    2016-09-01

    In a study of the metal-related ion generation mechanism in matrix-assisted laser desorption ionization (MALDI), crystals of matrix used in MALDI were grown from matrix- and salt-containing solutions. The intensities of metal ion and metal adducts of the matrix ion obtained from unwashed crystals were higher than those from crystals washed with deionized water, indicating that metal ions and metal adducts of the matrix ions are mainly generated from the surface of crystals. The contributions of preformed metal ions and metal adducts of the matrix ions inside the matrix crystals were minor. Metal adducts of the matrix and analyte ion intensities generated from a mixture of dried matrix, salt, and analyte powders were similar to or higher than those generated from the powder of dried droplet crystals, indicating that the contributions of the preformed metal adducts of the matrix and analyte ions were insignificant. Correlation between metal-related ion intensity fluctuation and protonated ion intensity fluctuation was observed, indicating that the generation mechanism of the metal-related ions is similar to that of the protonated ions. Because the thermally induced proton transfer model effectively describes the generation of the protonated ions, we suggest that metal-related ions are mainly generated from the salt dissolution in the matrix melted by the laser. Graphical Abstract ᅟ. PMID:27306427

  12. Formation of Metal-Related Ions in Matrix-Assisted Laser Desorption Ionization

    NASA Astrophysics Data System (ADS)

    Lee, Chuping; Lu, I.-Chung; Hsu, Hsu Chen; Lin, Hou-Yu; Liang, Sheng-Ping; Lee, Yuan-Tseh; Ni, Chi-Kung

    2016-06-01

    In a study of the metal-related ion generation mechanism in matrix-assisted laser desorption ionization (MALDI), crystals of matrix used in MALDI were grown from matrix- and salt-containing solutions. The intensities of metal ion and metal adducts of the matrix ion obtained from unwashed crystals were higher than those from crystals washed with deionized water, indicating that metal ions and metal adducts of the matrix ions are mainly generated from the surface of crystals. The contributions of preformed metal ions and metal adducts of the matrix ions inside the matrix crystals were minor. Metal adducts of the matrix and analyte ion intensities generated from a mixture of dried matrix, salt, and analyte powders were similar to or higher than those generated from the powder of dried droplet crystals, indicating that the contributions of the preformed metal adducts of the matrix and analyte ions were insignificant. Correlation between metal-related ion intensity fluctuation and protonated ion intensity fluctuation was observed, indicating that the generation mechanism of the metal-related ions is similar to that of the protonated ions. Because the thermally induced proton transfer model effectively describes the generation of the protonated ions, we suggest that metal-related ions are mainly generated from the salt dissolution in the matrix melted by the laser.

  13. Formation of Metal-Related Ions in Matrix-Assisted Laser Desorption Ionization

    NASA Astrophysics Data System (ADS)

    Lee, Chuping; Lu, I.-Chung; Hsu, Hsu Chen; Lin, Hou-Yu; Liang, Sheng-Ping; Lee, Yuan-Tseh; Ni, Chi-Kung

    2016-09-01

    In a study of the metal-related ion generation mechanism in matrix-assisted laser desorption ionization (MALDI), crystals of matrix used in MALDI were grown from matrix- and salt-containing solutions. The intensities of metal ion and metal adducts of the matrix ion obtained from unwashed crystals were higher than those from crystals washed with deionized water, indicating that metal ions and metal adducts of the matrix ions are mainly generated from the surface of crystals. The contributions of preformed metal ions and metal adducts of the matrix ions inside the matrix crystals were minor. Metal adducts of the matrix and analyte ion intensities generated from a mixture of dried matrix, salt, and analyte powders were similar to or higher than those generated from the powder of dried droplet crystals, indicating that the contributions of the preformed metal adducts of the matrix and analyte ions were insignificant. Correlation between metal-related ion intensity fluctuation and protonated ion intensity fluctuation was observed, indicating that the generation mechanism of the metal-related ions is similar to that of the protonated ions. Because the thermally induced proton transfer model effectively describes the generation of the protonated ions, we suggest that metal-related ions are mainly generated from the salt dissolution in the matrix melted by the laser.

  14. Metal ions affecting the gastrointestinal system including the liver.

    PubMed

    Naughton, Declan P; Nepusz, Tamás; Petroczi, Andrea

    2011-01-01

    In the present context, metal ions can be categorized into several classes including those that are essential for life and those that have no known biological function and thus can be considered only as potentially hazardous. Many complexities arise with regard to metal toxicity and there is a paucity of studies relating to many metals which are frequent components of the diet. For many people ingestion of mineral supplements is considered a risk-free health choice despite growing evidence to the contrary. Numerous approaches have been developed to assess risk associated with ingestion of metal ions. These include straightforward estimation of safe limits such as oral reference dose which are often based on data derived from animal experiments. More convoluted approaches such as the Target Hazard Quotient involve assessment of hazard with frequent exposure over long durations such as a lifetime. The latter calculation also affords facile consideration of the effects of many metals together. In many cases, rigorous data are unavailable, hence, large factors of uncertainty are employed to relate risk to humans. Owing to the nature of metal toxicity, data pertaining to the gastrointestinal tract and liver are often acquired from diseases of metal homeostasis or episodes of considerable metal overload. Whilst these studies provide evidence for mechanisms of metal-induced toxicity such as enhancing oxidative stress, extrapolation of these results to healthy individuals or patients with chronic inflammatory diseases is not straightforward. In summary, the diverse nature of metals and their effects on human tissues along with a paucity of studies on the full range of their effects, warrant further in-depth studies on the association of metals to ageing, chronic inflammatory diseases, and cancer. PMID:21473378

  15. Adsorption characteristics of metal ions on chitosan chemically modified by D-galactose

    SciTech Connect

    Kondo, Kazuo; Sumi, Hisaharu; Matsumoto, Michiaki

    1996-07-01

    The adsorption characteristics of metal ions on chitosan chemically modified by D-galactose were examined. The pH dependency on the distribution ratio was found to be affected by the valency of the metal ion, and the apparent adsorption equilibrium constants of the metal ions were determined. The order of adsorption of the metal ions is Ga > In > Nd > Eu for the trivalent metal ions and Cu > Ni > Co for the divalent metal ions. It is believed that amino and hydroxyl groups in the chitosan act as a chelating ligand.

  16. Metal ion bombardment of onion skin cell wall

    SciTech Connect

    Sangyuenyongpipat, S.; Vilaithong, T.; Yu, L.D.; Verdaguer, A.; Ratera, I.; Ogletree, D.F.; Monteiro, O.R.; Brown, I.G.

    2004-05-10

    Ion bombardment of living cellular material is a novel subfield of ion beam surface modification that is receiving growing attention from the ion beam and biological communities. Although it has been demonstrated that the technique is sound, in that an adequate fraction of the living cells can survive both the vacuum environment and energetic ion bombardment, there remains much uncertainty about the process details. Here we report on our observations of onion skin cells that were subjected to ion implantation, and propose some possible physical models that tend to support the experimental results. The ion beams used were metallic (Mg, Ti, Fe, Ni, Cu), mean ion energy was typically 30keV, and the implantation fluence was in the range 1014 1016 ions/cm2. The cells were viewed using Atomic Force Microscopy, revealing the formation of microcrater-like structures due to ion bombardment. The implantation depth profile was measured with Rutherford backscattering spectrometry and compared to the results of the TRIM, T-DYN and PROFILE computer codes.

  17. Laser-driven ion sources for metal ion implantation for the reduction of dry friction

    SciTech Connect

    Boody, F. P.; Juha, L.; Kralikova, B.; Krasa, J.; Laska, L.; Masek, K.; Pfeifer, M.; Rohlena, K.; Skala, J.; Straka, P.; Perina, V.; Woryna, E.; Giersch, D.; Hoepfl, R.; Kelly, J. C.; Hora, H.

    1997-04-15

    The anomalously high ion currents and very high ionization levels of laser-produced plasmas give laser-driven ion sources significant advantages over conventional ion sources. In particular, laser-driven ion sources should provide higher currents of metal ions at lower cost, for implantation into solids in order to improve their material properties such as friction. The energy and charge distributions for Pb and Sn ions produced by ablation of solid targets with {approx}25 J, {approx}300 ps iodine laser pulses, resulting in up to 48-times ionized MeV ions, as well as the optimization of focus position, are presented. Implantation of these ions into Ck-45 steel, without electrostatic acceleration, produced profiles with two regions. Almost all of the ions were implanted in a near surface region a few nm deep. However, a small but significant number of ions were implanted as deep as could be measured with Rutherford backscattering (RBS), here 150 nm for Sn and 250 nm for Pb. For the implanted ion densities and profiles achieved, no change in the coefficient of friction was measured for either ion.

  18. Experimental study of transition metal ion doping on TiO2 with photocatalytic behavior.

    PubMed

    Siddhapara, K S; Shah, D V

    2014-08-01

    In this research, we have studied the doping behaviors of three transition metal ion dopants on the crystal phase, particle sizes, XRD patterns, EDAX spectra, and photoreactivity of TiO2 nanoparticles. Test metal ion concentrations ranged from 1% to 4 at.%, we report the growth of [Fe, Co and Mn]xTiO2 nanocrystals prepared by Sol-Gel technique, followed by freeze-drying treatment at -30 °C temperature for 12 hrs. The obtained Gel was thermally treated at different temperature like 200 °C, 400 °C, 600 °C, 800 °C. Thermal gravimetric analysis (TGA) shows that dopant concentration affects thermal decomposition. The photoreactivities of transition metal ion-doped TiO2 nanoparticles under UV irradiation were quantified by the degradation of formaldehyde. PMID:25936115

  19. Depth concentrations of deuterium ions implanted into some pure metals and alloys

    NASA Astrophysics Data System (ADS)

    Didyk, A. Yu.; Wiśniewski, R.; Kitowski, K.; Kulikauskas, V.; Wilczynska, T.; Hofman, A.; Shiryaev, A. A.; Zubavichus, Ya. V.

    2012-01-01

    Pure metals (Cu, Ti, Zr, V, Pd) and diluted Pd alloys (Pd-Ag, Pd-Pt, Pd-Ru, Pd-Rh) were implanted by 25-keV deuterium ions at fluences in the range (1.2-2.3) × 1022 m-2. The post-treatment depth distributions of deuterium ions were measured 10 days and three months after the implantation by using Elastic Recoil Detection Analysis (ERDA) and Rutherford Backscattering (RBS). Comparison of the obtained results allowed us to make conclusions about relative stability of deuterium and hydrogen gases in pure metals and diluted Pd alloys. Very high diffusion rates of implanted deuterium ions in V and Pd pure metals and Pd alloys were observed. Small-angle X-ray scattering revealed formation of nanosized defects in implanted corundum and titanium.

  20. The chemistry of river-lake systems in the context of permafrost occurrence (Mongolia, Valley of the Lakes). Part I. Analysis of ion and trace metal concentrations

    NASA Astrophysics Data System (ADS)

    Szopińska, Małgorzata; Szumińska, Danuta; Polkowska, Żaneta; Machowiak, Katarzyna; Lehmann, Sara; Chmiel, Stanisław

    2016-07-01

    This study provides a description of water chemistry in river-lake systems located in central Mongolia, at the borderline of permafrost occurrence. The analysis involved water samples collected from two river-lake systems: Baydrag River-Böön Tsagaan Lake system, and Shargalyuut/Tuyn Rivers-Orog Lake system. In the water samples, ions and trace elements were detected and quantified. Additionally, the parameters of pH, electrical conductivity (SEC), total dissolved solids (TDS) and total organic carbon (TOC) were determined. Principal Component Analysis (PCA) was performed on the sample results. Water chemistry is mostly influenced by geochemical and hydrometeorological processes. Permafrost thawing could increase the concentration of nitrogen (NH4+, NO3-) as well as Na+ and Ca2+, Cl- and SO42 -. However, it may also be an effect of other factors such as livestock farming. Seasonal drying out of lakes (e.g., Lake Orog) may also influence water chemistry by deflation of evaporites from exposed lake beds and, at the same time, with lower concentration of chemical compounds in water. The PCA shows that water samples can be divided into two groups. The first group contains lake samples, where water chemistry is shaped by prevailing evaporation processes, whereas the second includes samples from rivers and springs. Water chemistry of the latter is predominantly influenced by geochemical and hydro-meteorological processes.

  1. Electropositive bivalent metallic ion unsaturated polyester complexed polymer concrete

    DOEpatents

    Sugama, Toshifumi; Kukacka, Lawrence E.; Horn, William H.

    1985-01-01

    Quick setting polymer concrete compositions with excellent structural properties are disclosed; these polymer concrete compositions are mixtures of unsaturated polyesters and crosslinking monomers together with appropriate initiators and promoters in association with aggregate, which may be wet, and with a source of bivalent metallic ions.

  2. Electropositive bivalent metallic ion unsaturated polyester complexed polymer concrete

    DOEpatents

    Sugama, T.; Kukacka, L.E.; Horn, W.H.

    1981-11-04

    Quick setting polymer concrete compositions which are mixtures of unsaturated polyesters and crosslinking monomers together with appropriate initiators and promoters in association with aggregate which may be wet and a source of bivalent metallic ions which will set to polymer concrete with excellent structural properties.

  3. Electropositive bivalent metallic ion unsaturated polyester complexed polymer concrete

    DOEpatents

    Sugama, T.; Kukacka, L.E.; Horn, W.H.

    1983-05-13

    Quick setting polymer concrete compositions are described which are mixtures of unsaturated polyesters and crosslinking monomers together with appropriate initiators and promoters in association with aggregate which may be wet and a source of bivalent metallic ions which will set to polymer concrete with excellent structural properties.

  4. Principles Governing Metal Ion Selectivity in Ion Channel Proteins

    NASA Astrophysics Data System (ADS)

    Lim, Carmay

    2014-03-01

    Our research interests are to (i) unravel the principles governing biological processes and use them to identify novel drug targets and guide drug design, and (ii) develop new methods for studying macromolecular interactions. This talk will provide an overview of our work in these two areas and an example of how our studies have helped to unravel the principles underlying the conversion of Ca2+-selective to Na+-selective channels. Ion selectivity of four-domain voltage-gated Ca2+(Cav) and sodium (Nav) channels, which is controlled by the selectivity filter (SF, the narrowest region of an open pore), is crucial for electrical signaling. Over billions of years of evolution, mutation of the Glu from domain II/III in the EEEE/DEEA SF of Ca2+-selective Cav channels to Lys made these channels Na+-selective. This talk will delineate the physical principles why Lys is sufficient for Na+/Ca2+selectivity and why the DEKA SF is more Na+-selective than the DKEA one.

  5. Tetrabutylammonium-modified clay film electrodes: characterization and application to the detection of metal ions.

    PubMed

    Maghear, Adela; Tertiş, Mihaela; Fritea, Luminţa; Marian, Iuliu O; Indrea, Emil; Walcarius, Alain; Săndulescu, Robert

    2014-07-01

    This work describes the preparation and characterization of smectite clay partially exchanged with tetrabutylammonium ions (TBA(+)) and its subsequent deposition onto glassy carbon electrode (GCE) for application to the preconcentration electroanalysis of metal ions (Cd, Pb, and Cu). Such partial exchange of TBA(+) induces the expansion of the interlayer region between the clay sheets (as ascertained by XRD) while maintaining its ion exchange capacity, which resulted in enhanced mass transport rates (as pointed out by electrochemical monitoring of permeability properties of these thin (organo)clay films on GCE). This principle was applied here to the anodic stripping square wave voltammetric analysis of metal ions after accumulation at open circuit. Among others, detection limits as low as 3.6×10(-8)M for copper and 7.2×10(-8)M for cadmium have been achieved. PMID:24840412

  6. [Spectroscopic studies on transition metal ions in colored diamonds].

    PubMed

    Meng, Yu-Fei; Peng, Ming-Sheng

    2004-07-01

    Transition metals like nickel, cobalt and iron have been often used as solvent catalysts in high pressure high temperature (HPHT) synthesis of diamond, and nickel and cobalt ions have been found in diamond lattice. Available studies indicated that nickel and cobalt ions could enter the lattice as interstitial or substitutional impurities and form complexes with nitrogen. Polarized microscopy, SEM-EDS, EPR, PL and FTIR have been used in this study to investigate six fancy color natural and synthetic diamonds in order to determine the spectroscopic characteristics and the existing forms of transition metal ions in colored diamond lattice. Cobalt-related optical centers were first found in natural chameleon diamonds, and some new nickel and cobalt-related optical and EPR centers have also been detected in these diamond samples. PMID:15766067

  7. Method for removing metal ions from solution with titanate sorbents

    DOEpatents

    Lundquist, Susan H.; White, Lloyd R.

    1999-01-01

    A method for removing metal ions from solution comprises the steps of providing titanate particles by spray-drying a solution or slurry comprising sorbent titanates having a particle size up to 20 micrometers, optionally in the presence of polymer free of cellulose functionality as binder, said sorbent being active towards heavy metals from Periodic Table (CAS version) Groups IA, IIA, IB, IIB, IIIB, and VIII, to provide monodisperse, substantially spherical particles in a yield of at least 70 percent of theoretical yield and having a particle size distribution in the range of 1 to 500 micrometers. The particles can be used free flowing in columns or beds, or entrapped in a nonwoven, fibrous web or matrix or a cast porous membrane, to selectively remove metal ions from aqueous or organic liquid.

  8. Metal ion influence on eumelanin fluorescence and structure

    NASA Astrophysics Data System (ADS)

    Sutter, Jens-Uwe; Birch, David J. S.

    2014-06-01

    Melanin has long been thought to have an unworkably weak and complex fluorescence, but here we study its intrinsic fluorescence in order to demonstrate how metal ions can be used to control the rate of formation, constituents and structure of eumelanin formed from the well-known laboratory auto-oxidation of 3,4-dihydroxy-L-phenylalanine (L-DOPA). The effect on eumelanin absorption and fluorescence of a range of solvated metal ions is reported including Cu, Zn, Ni, Na and K. Monovalent cations and Zn have little effect, but the effect of transition metal cations can be considerable. For example, at pH 10, copper ions are shown to accelerate the onset of eumelanin formation, but not the rate of formation once it commences, and simplify the usual complex structure and intrinsic fluorescence of eumelanin in a way that is consistent with an increased abundance of 5,5-dihydroxyindole-2-carboxylic acid (DHICA). The presence of a dominant 6 ns fluorescence decay time at 480 nm, when excited at 450 nm describes a distinct photophysical species, which we tentatively assign to small oligomers. Copper is well-known to normally quench fluorescence, but increasing amounts of copper surprisingly leads to an increase in the fluorescence decay time of eumelanin, while reducing the fluorescence intensity, suggesting copper modification of the excited state. Such results have bearing on diverse areas. The most accepted morphology for melanin is that of a graphite-like sheet structure, and one which readily binds metal ions, an interaction that is thought to have an important, though as yet unclear bearing on several areas of medicine including neurology. There is also increasing interest in bio-mimicry by preparing and labelling sheet structures with metal ions for new electronic and photonic materials.

  9. Chitosan removes toxic heavy metal ions from cigarette mainstream smoke

    NASA Astrophysics Data System (ADS)

    Zhou, Wen; Xu, Ying; Wang, Dongfeng; Zhou, Shilu

    2013-09-01

    This study investigated the removal of heavy metal ions from cigarette mainstream smoke using chitosan. Chitosan of various deacetylation degrees and molecular weights were manually added to cigarette filters in different dosages. The mainstream smoke particulate matter was collected by a Cambridge filter pad, digested by a microwave digestor, and then analyzed for contents of heavy metal ions, including As(III/V), Pb(II), Cd(II), Cr(III/VI) and Ni(II), by graphite furnace atomic absorption spectrometry (GFAAS). The results showed that chitosan had a removal effect on Pb(II), Cd(II), Cr(III/VI) and Ni(II). Of these, the percent removal of Ni(II) was elevated with an increasing dosage of chitosan. Chitosan of a high deace tylation degree exhibited good binding performance toward Cd(II), Cr(III/VI) and Ni(II), though with poor efficiency for Pb(II). Except As(III/V), all the tested metal ions showed similar tendencies in the growing contents with an increasing chitosan molecular weight. Nonetheless, the percent removal of Cr(III/VI) peaked with a chitosan molecular weight of 200 kDa, followed by a dramatic decrease with an increasing chitosan molecular weight. Generally, chitosan had different removal effects on four out of five tested metal ions, and the percent removal of Cd(II), Pb(II), Cr(III/VI) and Ni(II) was approximately 55%, 45%, 50%, and 16%, respectively. In a word, chitosan used in cigarette filter can remove toxic heavy metal ions in the mainstream smoke, improve cigarette safety, and reduce the harm to smokers.

  10. Synergistic cytotoxic effects of ions released by zinc-aluminum bronze and the metallic salts on osteoblastic cells.

    PubMed

    Grillo, Claudia A; Morales, María L; Mirífico, María V; Fernández Lorenzo de Mele, Mónica A

    2013-07-01

    The use of copper-based alloys for fixed dental crowns and bridges is increasingly widespread in several countries. The aim of this work is to study the dissolution of a zinc-aluminum-bronze and the cytotoxic effects of the ions released on UMR-106 osteoblastic cell line. Two sources of ions were used: (1) ions released by the metal alloy immersed in the cell culture and (2) salts of the metal ions. Conventional electrochemical techniques, atomic absorption spectroscopy [to obtain the average concentration of ions (AC) in solution], and energy dispersive X-ray (EDX) spectroscopy analysis were used to study the corrosion process. Corrosion tests revealed a strong influence of the composition of the electrolyte medium and the immersion time on the electrochemical response. The cytotoxicity was evaluated with (a) individual ions, (b) combinations of two ions, and (c) the mixture of all the ions released by a metal disc of the alloy. Importantly, synergistic cytotoxic effects were found when Al-Zn ion combinations were used at concentration levels lower than the cytotoxic threshold values of the individual ions. Cytotoxic effects in cells in the vicinity of the metal disc were also found. These results were interpreted considering synergistic effects and a diffusion controlled mechanism that yields to concentration levels, in the metal surroundings, several times higher than the measured AC value. PMID:23596152