Sample records for advantageous metal ion

  1. Clinical advantages of carbon-ion radiotherapy

    Tsujii, Hirohiko; Kamada, Tadashi; Baba, Masayuki; Tsuji, Hiroshi; Kato, Hirotoshi; Kato, Shingo; Yamada, Shigeru; Yasuda, Shigeo; Yanagi, Takeshi; Kato, Hiroyuki; Hara, Ryusuke; Yamamoto, Naotaka; Mizoe, Junetsu


    Carbon-ion radiotherapy (C-ion RT) possesses physical and biological advantages. It was started at NIRS in 1994 using the Heavy Ion Medical Accelerator in Chiba (HIMAC); since then more than 50 protocol studies have been conducted on almost 4000 patients with a variety of tumors. Clinical experiences have demonstrated that C-ion RT is effective in such regions as the head and neck, skull base, lung, liver, prostate, bone and soft tissues, and pelvic recurrence of rectal cancer, as well as for histological types including adenocarcinoma, adenoid cystic carcinoma, malignant melanoma and various types of sarcomas, against which photon therapy could be less effective. Furthermore, when compared with photon and proton RT, a significant reduction of overall treatment time and fractions has been accomplished without enhancing toxicities. Currently, the number of irradiation sessions per patient averages 13 fractions spread over approximately three weeks. This means that in a carbon therapy facility a larger number of patients than is possible with other modalities can be treated over the same period of time.

  2. Metal Ions in Unusual Valency States.

    Sellers, Robin M.


    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)

  3. Engineering of microorganisms towards recovery of rare metal ions

    Kuroda, Kouichi; Ueda, Mitsuyoshi [Kyoto Univ. (Japan). Div. of Applied Life Sciences


    The bioadsorption of metal ions using microorganisms is an attractive technology for the recovery of rare metal ions as well as removal of toxic heavy metal ions from aqueous solution. In initial attempts, microorganisms with the ability to accumulate metal ions were isolated from nature and intracellular accumulation was enhanced by the overproduction of metal-binding proteins in the cytoplasm. As an alternative, the cell surface design of microorganisms by cell surface engineering is an emerging strategy for bioadsorption and recovery of metal ions. Cell surface engineering was firstly applied to the construction of a bioadsorbent to adsorb heavy metal ions for bioremediation. Cell surface adsorption of metal ions is rapid and reversible. Therefore, adsorbed metal ions can be easily recovered without cell breakage, and the bioadsorbent can be reused or regenerated. These advantages are suitable for the recovery of rare metal ions. Actually, the cell surface display of a molybdate-binding protein on yeast led to the enhanced adsorption of molybdate, one of the rare metal ions. An additional advantage is that the cell surface display system allows high-throughput screening of protein/peptide libraries owing to the direct evaluation of the displayed protein/peptide without purification and concentration. Therefore, the creation of novel metal-binding protein/ peptide and engineering of microorganisms towards the recovery of rare metal ions could be simultaneously achieved. (orig.)

  4. [Development of metal ions analysis by ion chromatography].

    Yu, Hong; Wang, Yuxin


    Analysis of metal ions by ion chromatography, including cation-exchange ion chromatography, anion-exchange ion chromatography and chelation ion chromatography, is reviewed. The cation-exchange ion chromatography is a main method for the determination of metal ions. Stationary phases in cation-exchange ion chromatography are strong acid cation exchanger (sulfonic) and weak acid cation exchanger (carboxylic). Alkali metal ions, alkaline earth metal ions, transition metal ions, rare earth metal ions, ammonium ions and amines can be analyzed by cation-exchange ion chromatography with a suitable detector. The anion-exchange ion chromatography is suitable for the separation and analysis of alkaline earth metal ions, transition metal ions and rare earth metal ions. The selectivity for analysis of metal ions with anion-exchange ion chromatography is good. Simultaneous determination of metal ions and inorganic anions can be achieved using anion-exchange ion chromatography. Chelation ion chromatography is suitable for the determination of trace metal ions in complex matrices. A total of 125 references are cited.

  5. Protontherapy versus carbon ion therapy advantages, disadvantages and similarities

    d’Ávila Nunes, Marcos


    This book presents a comparison analysis of two cancer treatment therapies: carbon ion therapy and protontherapy. It is divided in 5 sections. The first ones gives the reader a brief history of Radiotherapy and types of radiation. In the second section, the techniques and equipments, including new ones in development such as Cyclinac , Laser and DWA, are described. The third section describes biophysical (such as stopping power and LET) and biological (such as RBE and OER) properties, the fundamental experiments and clinical area. The fourth section presents models and the fifth section compares both techniques, showing advantages and disadvantages of each, and their similarities.

  6. Material Removes Heavy Metal Ions From Water

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


    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.

  7. Bacterial antimicrobial metal ion resistance.

    Hobman, Jon L; Crossman, Lisa C


    Metals such as mercury, arsenic, copper and silver have been used in various forms as antimicrobials for thousands of years with until recently, little understanding of their mode of action. The discovery of antibiotics and new organic antimicrobial compounds during the twentieth century saw a general decline in the clinical use of antimicrobial metal compounds, with the exception of the rediscovery of the use of silver for burns treatments and niche uses for other metal compounds. Antibiotics and new antimicrobials were regarded as being safer for the patient and more effective than the metal-based compounds they supplanted. Bacterial metal ion resistances were first discovered in the second half of the twentieth century. The detailed mechanisms of resistance have now been characterized in a wide range of bacteria. As the use of antimicrobial metals is limited, it is legitimate to ask: are antimicrobial metal resistances in pathogenic and commensal bacteria important now? This review details the new, rediscovered and 'never went away' uses of antimicrobial metals; examines the prevalence and linkage of antimicrobial metal resistance genes to other antimicrobial resistance genes; and examines the evidence for horizontal transfer of these genes between bacteria. Finally, we discuss the possible implications of the widespread dissemination of these resistances on re-emergent uses of antimicrobial metals and how this could impact upon the antibiotic resistance problem. © 2014 The Authors.

  8. Rational Design of Metal Ion Sequestering Agents

    Raymond, Kenneth N.; Xu, Jide; Gramer, Christine


    This project addresses the fundamental issues and requirements for developing hazardous metal ion separation technologies applicable to the treatment and disposal of radioactive waste. Our research encompasses the following areas: the design and synthesis of metal ion specific sequestering ligands, structural and thermodynamic investigations of these ligand and the complexes formed with targeted metal ions, and the development and incorporation of these ligands into applied separation technologies as highly effective materials for hazardous metal ion decontamination.

  9. Competing binding of metal ions with protein studied by microdialysis

    GUO; Ming(郭明); KONG; Liang(孔亮); MAO; Xiqin(毛希琴); LI; Xin(历欣); ZOU; Hanfa(邹汉法)


    A method has been established to study the competing binding of metal ions with protein by a combined technique of microdialysis with high performance liquid chromatography (HPLC). Ni2+, Cd2+, Zn2+, Cu2+ and human serum albumin (HSA) were chosen as model metal ions and protein. The experimental results show that Ni2+ and Cu2+ share a common primary binding site on HSA, and Zn2+ and Cd2+ share a different common primary binding site from them, but there is a common multi-metal binding site for all of those four metal ions. This method show advantages of fast sampling, easily to be operated and especially to be useful when ideal spectroscopic probes are not available for the study of interaction between protein and metal ions.

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

    Budimir, Ana


    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.

  11. Advantages of ion-exchange chromatography for oligonucleotide analysis.

    Cook, Ken; Thayer, Jim


    The rapid development of therapeutic oligonucleotides (ONs) has created a need for in-depth characterization of ONs, beyond previous requirements. The natural migration to LC-MS requires the use of chromatography with MS-compatible eluents to introduce the large, highly charged biopolymers into the mass spectrometer. Most frequently this employs ion-pair reversed-phase liquid chromatography, which may leave gaps in the characterization, but these can be filled with the use of high-resolution ion-exchange chromatography. Several classes of isobaric isomers are among the impurities that will require further separation prior to MS analysis. This review shows how the use of ion exchange as an additional orthogonal analytical method can be used as standalone or interfaced with MS to achieve the highest possible analytical coverage in the characterization and quantification of impurities present in single- and double-stranded ON formulations. Some of these techniques have been in use for some time and the importance of others is just being recognized.

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

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


    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.

  13. Advantages of fluoride ion cleaning at sub-atmospheric pressure

    Miglietti, W


    Full Text Available stream_source_info miglietti_1998.pdf.txt stream_content_type text/plain stream_size 34169 Content-Encoding UTF-8 stream_name miglietti_1998.pdf.txt Content-Type text/plain; charset=UTF-8 En‘ineerin‘ Failure Analysis... are present in the base metal\\ the FIC process depletes these elements from the surface\\ thereby improving the braze ~ow and repair of the cracked components[ The objective of this paper is to highlight the bene_ts of using the FIC process at sub...

  14. Metal Ion Controlled Polymorphism of a Peptide

    Hemmingsen, Lars Bo Stegeager; Jancso, Attila; Szunyogh, Daniel;


    , …) in the peptide, and the ligand and structural preferences of the metal ion (in our studies Zn2+, Cd2+, Hg2+, Cu+/2+). Simultaneously, new species such as metal ion bridged ternary complexes or even oligomers may be formed. In recent previous studies we have observed similar polymorphism of zinc finger model...

  15. Measuring free metal ion concentrations in multicomponent solutions using Donnan Membrane Technique

    Kalis, E.J.J.; Temminghoff, E.J.M.; Weng, L.P.; Riemsdijk, van W.H.


    Among speciation techniques that are able to measure free metal ion concentrations, the Donnan membrane technique (DMT) has the advantage that it can measure many different free metal ion concentrations simultaneously in a multicomponent sample. Even though the DMT has been applied to several system

  16. Recovery of metal ions by microfungal filters.

    Wales, D S; Sagar, B F


    Many microfungi contain chitin/chitosan as an integral part of the cell wall structure. The binding of toxic and heavy metal ions by chitosan or partly deacetylated chitin is a direct consequence of the base strength of the primary amine group and is most effective for those metals that form complexes with ammonia. Of the microfungi studied, hyphae from Mucor mucedo and Rhizomucor miehei, after treatment with hydroxide to expose the chitin/chitosan, were found to be most effective in the capture of metal ions. Chemically treated mycelia have so far been shown to bind silver, zinc, lead, copper, nickel, cobalt, cadmium, iron and chromium, with the efficiency of metal-ion binding apparently being inversely proportional to the valency state of the metal ions to be bound. Wet-laid papers produced from mixed slurries of treated mycelia and various conventional paper-making and textile fibres have exceptionally good tensile- and bursting-strength properties, particularly in the wet state. Papers containing 1 g treated mycelia removed up to 90% of various metal ions in solution (50 cm3, 1.5 mmol dm-3) with flow rates of 0.5 cm3 cm-2 min-1. However, the total metal-ion binding capacities of single-thickness microfungal papers are limited under constant flow conditions. The total volume flowing through the system before metal-ion breakthrough occurs increases in direct proportion to the number of sheets of microfungal paper but the concomitant reduction in flow rates becomes a limiting factor. Mycelia-containing structures that allow efficient metal-ion binding at commercially acceptable flow rates are currently being investigated.

  17. Metal Ion Modeling Using Classical Mechanics.

    Li, Pengfei; Merz, Kenneth M


    Metal ions play significant roles in numerous fields including chemistry, geochemistry, biochemistry, and materials science. With computational tools increasingly becoming important in chemical research, methods have emerged to effectively face the challenge of modeling metal ions in the gas, aqueous, and solid phases. Herein, we review both quantum and classical modeling strategies for metal ion-containing systems that have been developed over the past few decades. This Review focuses on classical metal ion modeling based on unpolarized models (including the nonbonded, bonded, cationic dummy atom, and combined models), polarizable models (e.g., the fluctuating charge, Drude oscillator, and the induced dipole models), the angular overlap model, and valence bond-based models. Quantum mechanical studies of metal ion-containing systems at the semiempirical, ab initio, and density functional levels of theory are reviewed as well with a particular focus on how these methods inform classical modeling efforts. Finally, conclusions and future prospects and directions are offered that will further enhance the classical modeling of metal ion-containing systems.

  18. Metal Ion Modeling Using Classical Mechanics


    Metal ions play significant roles in numerous fields including chemistry, geochemistry, biochemistry, and materials science. With computational tools increasingly becoming important in chemical research, methods have emerged to effectively face the challenge of modeling metal ions in the gas, aqueous, and solid phases. Herein, we review both quantum and classical modeling strategies for metal ion-containing systems that have been developed over the past few decades. This Review focuses on classical metal ion modeling based on unpolarized models (including the nonbonded, bonded, cationic dummy atom, and combined models), polarizable models (e.g., the fluctuating charge, Drude oscillator, and the induced dipole models), the angular overlap model, and valence bond-based models. Quantum mechanical studies of metal ion-containing systems at the semiempirical, ab initio, and density functional levels of theory are reviewed as well with a particular focus on how these methods inform classical modeling efforts. Finally, conclusions and future prospects and directions are offered that will further enhance the classical modeling of metal ion-containing systems. PMID:28045509

  19. Gas and metal ion sources

    Oaks, E. [High Current Electronics Institute, Tomsk (Russian Federation)]|[State Academy of Control System and Radioelectronics, Tomsk (Russian Federation); Yushkov, G. [High Current Electronics Institute, Tomsk (Russian Federation)


    The positive ion sources are now of interest owing to both their conventional use, e.g., as injectors in charged-particle accelerators and the promising capabilities of intense ion beams in the processes related to the action of ions on various solid surfaces. For industrial use, the sources of intense ion beams and their power supplies should meet the specific requirements as follows: They should be simple, technologically effective, reliable, and relatively low-cost. Since the scanning of an intense ion beam is a complicated problem, broad ion beams hold the greatest promise. For the best use of such beams it is desirable that the ion current density be uniformly distributed over the beam cross section. The ion beam current density should be high enough for the treatment process be accomplished for an acceptable time. Thus, the ion sources used for high-current, high-dose metallurgical implantation should provide for gaining an exposure dose of {approximately} 10{sup 17} cm{sup {minus}2} in some tens of minutes. So the average ion current density at the surface under treatment should be over 10{sup {minus}5} A/cm{sup 2}. The upper limit of the current density depends on the admissible heating of the surface under treatment. The accelerating voltage of an ion source is dictated by its specific use; it seems to lie in the range from {approximately}1 kV (for the ion source used for surface sputtering) to {approximately}100 kV and over (for the ion sources used for high-current, high-dose metallurgical implantation).

  20. Capacity-controllable nanocarriers for metal ions

    Yan, Y.; Keizer, de A.; Cohen Stuart, M.A.; Besseling, N.A.M.


    We report on capacity-controllable nanocarrier system for metal ions based on a novel kind of polymeric microemulsion. These microemulsions are formed in mixed systems of negatively charged metal-bisligand coordination polymers (cp), positively charged homopolyelectrolyte (hp), and positive-neutral

  1. Determination of metal ions by fluorescence anisotropy exhibits a broad dynamic range

    Thompson, Richard B.; Maliwal, Badri P.; Fierke, Carol A.


    Recently, we have shown that metal ions free in solution may be determined at low levels by fluorescence anisotropy (polarization) measurements. Anisotropy measurements enjoy the advantages of wavelength ratiometric techniques for determining metal ions such as calcium, because anisotropy measurements are ratiometric as well. Furthermore, fluorescence anisotropy may be imaged in the microscope. An advantage of anisotropy not demonstrated for wavelength ratiometric approaches using indicators such as Fura-2 and Indo-1 is that under favorable circumstances anisotropy-based determinations exhibit a much broader dynamic range in metal ion concentration. Determinations of free Zn(II) in the picomolar range are demonstrated.

  2. Bioavailability of Metal Ions and Evolutionary Adaptation

    Rolando P. Hong Enriquez


    Full Text Available The evolution of life on earth has been a long process that began nearly 3,5 x 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.

  3. Computational Design of Metal Ion Sequestering Agents

    Hay, Benjamin P.; Rapko, Brian M.


    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.

  4. Removal of toxic metal ions with magnetic hydrogels.

    Ozay, Ozgur; Ekici, Sema; Baran, Yakup; Aktas, Nahit; Sahiner, Nurettin


    Hydrogels, based on 2-acrylamido-2-methyl-1-propansulfonic acid (AMPS) were synthesized via photopolymerization technique and used for the preparation of magnetic responsive composite hydrogels. These composite hydrogels with magnetic properties were further utilized for the removal of toxic metal ions such as Cd(II), Co(II), Fe(II), Pb(II), Ni(II), Cu(II) and Cr(III) from aqueous environments. It was revealed that hydrogel networks with magnetic properties can effectively be utilized in the removal of pollutants. The results verified that magnetic iron particle containing p(AMPS) hydrogel networks provide advantageous over conventional techniques. Langmuir and Freundlich adsorption isotherms were applied for toxic metal removal and both isotherms were fit reasonably well for the metal ion absorptions.

  5. Separation of metal ions in nitrate solution by ultrasonic atomization

    Sato, Masanori; Ikeno, Masayuki; Fujii, Toshitaka


    In the ultrasonic atomization of metal nitrate solutions, the molar ratio of metal ions is changed between solution and mist. Small molar metal ions tend to be transferred to mist by ultrasonic wave acceleration, while large molar ions tend to remain in solution. As a result, metal ions can be separated by ultrasonic atomization. We show experimental data and propose a conceptual mechanism for the ultrasonic separation of metal ions.

  6. Assessment of potential advantages of relevant ions for particle therapy: A model based study

    Grün, Rebecca, E-mail: [Department of Biophysics, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt 64291 (Germany); Institute of Medical Physics and Radiation Protection, University of Applied Sciences Gießen, Gießen 35390 (Germany); Medical Faculty of Philipps-University Marburg, Marburg 35032 (Germany); Friedrich, Thomas; Krämer, Michael; Scholz, Michael [Department of Biophysics, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt 64291 (Germany); Zink, Klemens [Institute of Medical Physics and Radiation Protection, University of Applied Sciences Gießen, Gießen 35390, Germany and Department of Radiotherapy and Radiation Oncology, University Medical Center Giessen and Marburg, Marburg 35043 (Germany); Durante, Marco [Department of Biophysics, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt 64291, Germany and Department of Condensed Matter Physics, Darmstadt University of Technology, Darmstadt 64289 (Germany); Engenhart-Cabillic, Rita [Medical Faculty of Philipps-University Marburg, Marburg 35032, Germany and Department of Radiotherapy and Radiation Oncology, University Medical Center Giessen and Marburg, Marburg 35043 (Germany)


    Purpose: Different ion types offer different physical and biological advantages for therapeutic applications. The purpose of this work is to assess the advantages of the most commonly used ions in particle therapy, i.e., carbon ({sup 12}C), helium ({sup 4}He), and protons ({sup 1}H) for different treatment scenarios. Methods: A treatment planning analysis based on idealized target geometries was performed using the treatment planning software TRiP98. For the prediction of the relative biological effectiveness (RBE) that is required for biological optimization in treatment planning the local effect model (LEM IV) was used. To compare the three ion types, the peak-to-entrance ratio (PER) was determined for the physical dose (PER{sub PHY} {sub S}), the RBE (PER{sub RBE}), and the RBE-weighted dose (PER{sub BIO}) resulting for different dose-levels, field configurations, and tissue types. Further, the dose contribution to artificial organs at risk (OAR) was assessed and a comparison of the dose distribution for the different ion types was performed for a patient with chordoma of the skull base. Results: The study showed that the advantages of the ions depend on the physical and biological properties and the interplay of both. In the case of protons, the consideration of a variable RBE instead of the clinically applied generic RBE of 1.1 indicates an advantage in terms of an increased PER{sub RBE} for the analyzed configurations. Due to the fact that protons show a somewhat better PER{sub PHY} {sub S} compared to helium and carbon ions whereas helium shows a higher PER{sub RBE} compared to protons, both protons and helium ions show a similar RBE-weighted dose distribution. Carbon ions show the largest variation of the PER{sub RBE} with tissue type and a benefit for radioresistant tumor types due to their higher LET. Furthermore, in the case of a two-field irradiation, an additional gain in terms of PER{sub BIO} is observed when using an orthogonal field configuration

  7. Ion beam analysis of metal ion implanted surfaces

    Evans, P.J.; Chu, J.W.; Johnson, E.P.; Noorman, J.T. [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia); Sood, D.K. [Royal Melbourne Inst. of Tech., VIC (Australia)


    Ion implantation is an established method for altering the surface properties of many materials. While a variety of analytical techniques are available for the characterisation of implanted surfaces, those based on particle accelerators such as Rutherford backscattering (RBS) and nuclear reaction analysis (NRA) provide some of the most useful and powerful for this purpose. Application of the latter techniques to metal ion implantation research at ANSTO will be described with particular reference to specific examples from recent studies. Where possible, the information obtained from ion beam analysis will be compared with that derived from other techniques such as Energy Dispersive X-ray (EDX) and Auger spectroscopies. 4 refs., 5 figs.

  8. Kinetic study of heavy metal ions removal by ion exchange in batch conical air spouted bed

    T.M. Zewail


    Full Text Available Spouted bed contactor is a hybrid of fixed and fluidized bed contactors, which retains the advantages of each with good hydrodynamic conditions. The aim of the present study is to investigate the performance of a batch conical air spouted vessel for heavy metal removal by strong cation exchange resins (AMBERJET 1200 Na. The effect of various parameters such as type of heavy metal ions (Ni+2 and Pb+2, contact time, superficial air velocity and initial heavy metal ion concentration on % heavy metal ion removal has been investigated. It has been found that under optimum conditions 98% and 99% removal of Ni+2 and Pb+2 were achieved respectively. Several kinetic models were used to test the experimental data and to examine the controlling mechanism of the sorption process. The present results of Ni+2 and Pb+2 well fit pseudo second order kinetic model with a high correlation coefficient. Both film diffusion and intra-particle diffusion contribute to the ion exchange process. The present study revealed that spouted bed vessel may provide an effective alternative for conducting ion exchange reactions.

  9. [Development of trace metal ion analysis].

    Kobayashi, J


    Analyses of trace biologically essential or toxic ionic compounds found in the environment are very important. However, the lack of sensitivity and interference caused by coexisting components are often serious problems. To determine trace levels of metal ions without the above problems, new preconcentration and analytical methods have been developed. Firstly, three methods for the selective preconcentration of metal ions are shown below: 1) 3-Chloropyridazine-6-carbohydrazide was immobilized on glass beads supports to be used as a column packing material. Multi-metal ions were concentrated on the column and eluted selectively with several buffers and hydrochloric acid. The eluate was analyzed off-line by flame atomized-atomic absorption spectrometry (AAS). This method was able to determine sub-ppb levels of cupper- and cadmium-ions in environmental samples. 2) Salicylideneamino-2-thiophenol was immobilized on the supports. Aluminum ion was concentrated selectively on the column and eluted with nitric acid. The eluate was analyzed off-line by flameless-AAS or on-line by flow injection analysis using pyrocatechol violet for a post-column colorimetric reagent. These methods were able to determine ppb-ppt levels of aluminium in environmental samples and were suitable for its state-analysis. 3) Bathocuproinesulfonic acid was immobilized on the supports. Copper ion was concentrated selectively on the column and eluted with nitric acid. The eluate was analyzed on-line by flow injection analysis using bathocuproinesulfonic acid. This method was able to determine sub-ppb levels of copper in environmental samples. On the other hand, to analyze simultaneously trace metal ions and anions, capillary electrophoresis was performed using ethylenediaminetetraacetic acid as an electrolyte component. Simultaneous determination of several ions in mineral waters was achieved by the system.

  10. The Advantages of the Use of Ion- Selective Potentiometry in Relation to UV/VIS Spectroscopy

    Amra Bratovčić


    Full Text Available Electro analytical methods have a long history of development. Ion-selective potentiometry is one of the electro analytical methods. There are some advantages of the use of Ion selective potentiometry (ISP which is accurate, fast, economic and sensitive in relation to the standard method, UV/VIS spectroscopy. The development of potentiometric ion-selective electrodes is a very interesting field because it has a wide range of applications in determining ions in water and other mediums. The use of ion-selective electrodes enables the determination of ion species in a trace. Ion-selective electrodes are suitable for analysis in industry, for control processes, for physiological measurements and environmental monitoring. In recent years it was used for the determination of many ions in the food industry such as determination of calcium in milk products, fruit juice and different kinds of vegetables. In our experiment measurement of bottled water using ISP showed lower level of fluoride compared to measurement by UV/ VIS spectroscopy. This results confirmed higher sensitivity of ISE in reference to UV/VIS spectroscopy. By our experimental data we can conclude that the concentration in examined sample was within the allowed concentration according to World Health Organisation

  11. Liquid metal alloy ion sources—An alternative for focussed ion beam technology

    Bischoff, Lothar; Mazarov, Paul; Bruchhaus, Lars; Gierak, Jacques


    Today, Focused Ion Beam (FIB) processing is nearly exclusively based on gallium Liquid Metal Ion Sources (LMIS). But, many applications in the μm- or nm range could benefit from ion species other than gallium: local ion implantation, ion beam mixing, ion beam synthesis, or Focused Ion Beam Lithography (IBL). Therefore, Liquid Metal Alloy Ion Sources (LMAIS) represent a promising alternative to expand the remarkable application fields for FIB. Especially, the IBL process shows potential advantages over, e.g., electron beam or other lithography techniques: direct, resistless, and three-dimensional patterning, enabling a simultaneous in-situ process control by cross-sectioning and inspection. Taking additionally into account that the used ion species influences significantly the physical and chemical nature of the resulting nanostructures—in particular, the electrical, optical, magnetic, and mechanic properties leading to a large potential application area which can be tuned by choosing a well suited LMAIS. Nearly half of the elements of the periodic table are recently available in the FIB technology as a result of continuous research in this area during the last forty years. Key features of a LMAIS are long life-time, high brightness, and stable ion current. Recent developments could make these sources feasible for nano patterning issues as an alternative technology more in research than in industry. The authors will review existing LMAIS, LMIS other than Ga, and binary and ternary alloys. These physical properties as well as the fabrication technology and prospective domains for modern FIB applications will similarly be reviewed. Other emerging ion sources will be also presented and their performances discussed.

  12. Chitosan Hydrogel Structure Modulated by Metal Ions

    Nie, Jingyi; Wang, Zhengke; Hu, Qiaoling


    As one of the most important polysaccharide, chitosan (CS) has generated a great deal of interest for its desirable properties and wide applications. In the utilization of CS materials, hydrogel is a major and vital branch. CS has the ability to coordinate with many metal ions by a chelation mechanism. While most researchers focused on the applications of complexes between CS and metal ions, the complexes can also influence gelation process and structure of CS hydrogel. In the present work, such influence was studied with different metal ions, revealing two different kinds of mechanisms. Strong affinity between CS and metal ions leads to structural transition from orientation to multi-layers, while weak affinity leads to composite gel with in-situ formed inorganic particles. The study gave a better understanding of the gelation mechanism and provided strategies for the modulation of hydrogel morphology, which benefited the design of new CS-based materials with hierarchical structure and facilitated the utilization of polysaccharide resources.

  13. A metal ion regulated artificial metalloenzyme

    Bersellini, Manuela; Roelfes, Gerard


    Regulation of enzyme activity is essential in living cells. The rapidly increasing number of designer enzymes with new-to-nature activities makes it necessary to develop novel strategies for controlling their catalytic activity. Here we present the development of a metal ion regulated artificial met


    G. Q. Liu; Y.Y. Meng; S.H. Liu; Y.H. Hu


    DNA takes on multi-different conformations such as A-, B-, C-, D- and Z-form. These conformations can transit to one another when DNA deposited in some metal ions solutions or when changing the concentrations of the same metal ions. Here, several major conformational transitions of DNA induced by metal ions under different environment were introduced and the mechanism of the interaction of metal ions with DNA was discuss in detail.

  15. Ion irradiation effects on metallic nanocrystals

    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.

  16. Ohmic model for electrodeposition of metallic ions

    Gliozzi, A.S. [Department of Applied Science and Technology (DISAT), Politecnico di Torino, Corso Duca degli Abruzzi 29, 10129 Torino (Italy); Alexe-Ionescu, A.L. [Department of Applied Science and Technology (DISAT), Politecnico di Torino, Corso Duca degli Abruzzi 29, 10129 Torino (Italy); Department of Physics, University Politehnica of Bucharest, Splaiul Independentei 313, 060042 Bucharest (Romania); Barbero, G., E-mail: [Department of Applied Science and Technology (DISAT), Politecnico di Torino, Corso Duca degli Abruzzi 29, 10129 Torino (Italy)


    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.

  17. Fluorescence enhancement of photoswitchable metal ion sensors

    Sylvia, Georgina; Heng, Sabrina; Abell, Andrew D.


    Spiropyran-based fluorescence sensors are an ideal target for intracellular metal ion sensing, due to their biocompatibility, red emission frequency and photo-controlled reversible analyte binding for continuous signal monitoring. However, increasing the brightness of spiropyran-based sensors would extend their sensing capability for live-cell imaging. In this work we look to enhance the fluorescence of spiropyran-based sensors, by incorporating an additional fluorophore into the sensor design. We report a 5-membered monoazacrown bearing spiropyran with metal ion specificity, modified to incorporate the pyrene fluorophore. The effect of N-indole pyrene modification on the behavior of the spiropyran molecule is explored, with absorbance and fluorescence emission characterization. This first generation sensor provides an insight into fluorescence-enhancement of spiropyran molecules.

  18. Effects of metal ion adduction on the gas-phase conformations of protein ions.

    Flick, Tawnya G; Merenbloom, Samuel I; Williams, Evan R


    Changes in protein ion conformation as a result of nonspecific adduction of metal ions to the protein during electrospray ionization (ESI) from aqueous solutions were investigated using traveling wave ion mobility spectrometry (TWIMS). For all proteins examined, protein cations (and in most cases anions) with nonspecific metal ion adducts are more compact than the fully protonated (or deprotonated) ions with the same charge state. Compaction of protein cations upon nonspecific metal ion binding is most significant for intermediate charge state ions, and there is a greater reduction in collisional cross section with increasing number of metal ion adducts and increasing ion valency, consistent with an electrostatic interaction between the ions and the protein. Protein cations with the greatest number of adducted metal ions are no more compact than the lowest protonated ions formed from aqueous solutions. These results show that smaller collisional cross sections for metal-attached protein ions are not a good indicator of a specific metal-protein interaction in solution because nonspecific metal ion adduction also results in smaller gaseous protein cation cross sections. In contrast, the collisional cross section of α-lactalbumin, which specifically binds one Ca(2+), is larger for the holo-form compared with the apo-form, in agreement with solution-phase measurements. Because compaction of protein cations occurs when metal ion adduction is nonspecific, elongation of a protein cation may be a more reliable indicator that a specific metal ion-protein interaction occurs in solution.

  19. Liquid metal ion source analysis system

    Marriott, P.


    An analysis system for angular and mass resolved energy distribution measurements of liquid metal ion source beams has been constructed. The energy analyser has been calibrated, and preliminary on-axis energy distribution measurements of a gallium source operating between 0.26 and 30.0 have been made. These results closely agree with measurements reported by other workers, confirming the unusual FWHM behaviour of gallium sources below approx. 2

  20. Metal hydrides for lithium-ion batteries.

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


    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.

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

    Segal, M. J., E-mail: [iThemba LABS, P.O. Box 722, Somerset West 7130 (South Africa); University of Cape Town, Rondebosch, Cape Town 7700 (South Africa); Bark, R. A.; Thomae, R. [iThemba LABS, P.O. Box 722, Somerset West 7130 (South Africa); Donets, E. E.; Donets, E. D.; Boytsov, A.; Ponkin, D.; Ramsdorf, A. [Joint Institute for Nuclear Research, Joloit-Curie 6, 141980 Dubna, Moscow Region (Russian Federation)


    An assembly for a commercial Ga{sup +} 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{sup +} 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{sup +} and Au{sup +} ion beams will be reported as well.

  2. Fast growth increases the selective advantage of a mutation arising recurrently during evolution under metal limitation.

    Hsin-Hung Chou


    Full Text Available Understanding the evolution of biological systems requires untangling the molecular mechanisms that connect genetic and environmental variations to their physiological consequences. Metal limitation across many environments, ranging from pathogens in the human body to phytoplankton in the oceans, imposes strong selection for improved metal acquisition systems. In this study, we uncovered the genetic and physiological basis of adaptation to metal limitation using experimental populations of Methylobacterium extorquens AM1 evolved in metal-deficient growth media. We identified a transposition mutation arising recurrently in 30 of 32 independent populations that utilized methanol as a carbon source, but not in any of the 8 that utilized only succinate. These parallel insertion events increased expression of a novel transporter system that enhanced cobalt uptake. Such ability ensured the production of vitamin B(12, a cobalt-containing cofactor, to sustain two vitamin B(12-dependent enzymatic reactions essential to methanol, but not succinate, metabolism. Interestingly, this mutation provided higher selective advantages under genetic backgrounds or incubation temperatures that permit faster growth, indicating growth-rate-dependent epistatic and genotype-by-environment interactions. Our results link beneficial mutations emerging in a metal-limiting environment to their physiological basis in carbon metabolism, suggest that certain molecular features may promote the emergence of parallel mutations, and indicate that the selective advantages of some mutations depend generically upon changes in growth rate that can stem from either genetic or environmental influences.

  3. Fast growth increases the selective advantage of a mutation arising recurrently during evolution under metal limitation.

    Chou, Hsin-Hung; Berthet, Julia; Marx, Christopher J


    Understanding the evolution of biological systems requires untangling the molecular mechanisms that connect genetic and environmental variations to their physiological consequences. Metal limitation across many environments, ranging from pathogens in the human body to phytoplankton in the oceans, imposes strong selection for improved metal acquisition systems. In this study, we uncovered the genetic and physiological basis of adaptation to metal limitation using experimental populations of Methylobacterium extorquens AM1 evolved in metal-deficient growth media. We identified a transposition mutation arising recurrently in 30 of 32 independent populations that utilized methanol as a carbon source, but not in any of the 8 that utilized only succinate. These parallel insertion events increased expression of a novel transporter system that enhanced cobalt uptake. Such ability ensured the production of vitamin B(12), a cobalt-containing cofactor, to sustain two vitamin B(12)-dependent enzymatic reactions essential to methanol, but not succinate, metabolism. Interestingly, this mutation provided higher selective advantages under genetic backgrounds or incubation temperatures that permit faster growth, indicating growth-rate-dependent epistatic and genotype-by-environment interactions. Our results link beneficial mutations emerging in a metal-limiting environment to their physiological basis in carbon metabolism, suggest that certain molecular features may promote the emergence of parallel mutations, and indicate that the selective advantages of some mutations depend generically upon changes in growth rate that can stem from either genetic or environmental influences.

  4. Rational Design of Metal Ion Sequestering Agents

    Raymond, Kenneth N.


    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

  5. Laser materials based on transition metal ions

    Moncorgé, Richard


    The purpose of this presentation is to review the spectroscopic properties of the main laser materials based on transition metal ions which lead to noticeable laser performance at room temperature and, for very few cases, because of unique properties, when they are operated at cryogenic temperatures. The description also includes the materials which are currently being used as saturable absorbers for passive-Q-switching of a variety of other near- and mid-infrared solid state lasers. A substantial part of the article is devoted first to the description of the energy levels and of the absorption and emission transitions of the transition metal ions in various types of environments by using the well-known Tanabe-Sugano diagrams. It is shown in particular how these diagrams can be used along with other theoretical considerations to understand and describe the spectroscopic properties of ions sitting in crystal field environments of near-octahedral or near-tetrahedral symmetry. The second part is then dedicated to the description (positions and intensities) of the main absorption and emission features which characterize the different types of materials.

  6. Systems and methods for producing metal clusters; functionalized surfaces; and droplets including solvated metal ions

    Cooks, Robert Graham; Li, Anyin; Luo, Qingjie


    The invention generally relates to systems and methods for producing metal clusters; functionalized surfaces; and droplets including solvated metal ions. In certain aspects, the invention provides methods that involve providing a metal and a solvent. The methods additionally involve applying voltage to the solvated metal to thereby produce solvent droplets including ions of the metal containing compound, and directing the solvent droplets including the metal ions to a target. In certain embodiments, once at the target, the metal ions can react directly or catalyze reactions.

  7. Systems and methods for producing metal clusters; functionalized surfaces; and droplets including solvated metal ions

    Cooks, Robert Graham; Li, Anyin; Luo, Qingjie


    The invention generally relates to systems and methods for producing metal clusters; functionalized surfaces; and droplets including solvated metal ions. In certain aspects, the invention provides methods that involve providing a metal and a solvent. The methods additionally involve applying voltage to the solvated metal to thereby produce solvent droplets including ions of the metal containing compound, and directing the solvent droplets including the metal ions to a target. In certain embodiments, once at the target, the metal ions can react directly or catalyze reactions.

  8. Metal-ion rescue revisited: biochemical detection of site-bound metal ions important for RNA folding.

    Frederiksen, John K; Li, Nan-Sheng; Das, Rhiju; Herschlag, Daniel; Piccirilli, Joseph A


    Within the three-dimensional architectures of RNA molecules, divalent metal ions populate specific locations, shedding their water molecules to form chelates. These interactions help the RNA adopt and maintain specific conformations and frequently make essential contributions to function. Defining the locations of these site-bound metal ions remains challenging despite the growing database of RNA structures. Metal-ion rescue experiments have provided a powerful approach to identify and distinguish catalytic metal ions within RNA active sites, but the ability of such experiments to identify metal ions that contribute to tertiary structure acquisition and structural stability is less developed and has been challenged. Herein, we use the well-defined P4-P6 RNA domain of the Tetrahymena group I intron to reevaluate prior evidence against the discriminatory power of metal-ion rescue experiments and to advance thermodynamic descriptions necessary for interpreting these experiments. The approach successfully identifies ligands within the RNA that occupy the inner coordination sphere of divalent metal ions and distinguishes them from ligands that occupy the outer coordination sphere. Our results underscore the importance of obtaining complete folding isotherms and establishing and evaluating thermodynamic models in order to draw conclusions from metal-ion rescue experiments. These results establish metal-ion rescue as a rigorous tool for identifying and dissecting energetically important metal-ion interactions in RNAs that are noncatalytic but critical for RNA tertiary structure.

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

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


    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.

  10. Association of soil organic matter with metal phases examined by selective dissolution approach: limitations and advantages

    Wagai, R.; Mayer, L. M.


    Positive co-variation of organic matter (OM) with iron and aluminum phases has been known for decades in soil and, in case of OM-Fe, in marine sediments. More recent studies point to the metal control on the mean residence time of organic carbon in soils, suggesting that better understanding of the role of these metal phases and the nature of these organo-metal associations would help to improve the models of soil OM dynamics. We developed a selective dissolution approach to assess these associations (Wagai and Mayer, 2007; Wagai et al., 2013). By taking advantage of well-established extraction techniques that were targeted to dissolve specific metal and aluminosilicate phases in soil, we quantified the amounts of OM co-dissolved by the selective dissolution of these inorganic phases. The inherent limitations in this conceptually simple approach include the presence of C-based compounds (often as complexing agent for metal) in the extractants and the lack of selectivity when dissolving specific inorganic phases. The former was resolved by using nitrogen (N), instead of C, as a surrogate for OM because (i) soil N is mostly present as soil OM with relatively narrow C:N ratio, and (ii) the extractants are N free. We were able to partially overcome the lack of selectivity problem by comparing the co-dissolution of OM from a variety of extractants that use reductive, complexation, and acid/alkaline dissolutions. The potential advantages of our approach include the ability (i) to estimate the contribution of specific inorganic phases to OM stabilization, and (ii) to infer the possible modes of the organo-mineral associations that were extracted from field soils (e.g., adsorptive association vs. coprecipitation of organo-metallic complexes). In this presentation, we will further consider the advantages and limitations of this approach (e.g., methodological cautions), present some of the previous and new findings gained from this approach (including its application to

  11. Experiments and Researches on Production of Highly Charged Metallic Ions


    To satisfy the requirements of HIRFL (Heavy Ion Research Facility in Lanzhou), series of experiments have been done to produce metallic ion beams on the 14.5 GHz ECR ion source. By now, numerous methods have been tested, in which oven heating and MIVOC (Metallic Ion from Volatile Compounds) are both included.According to the experiments, the results show that oven heating is much better than MIVOC. In most of our

  12. Effects of metal ions on recombinant calcineurin A subunit


    Effects of metal ions on activities and solution conformations of calcineurin A subunit have been examined.The ability of several metal ions to activate calcineurin A has been tested with Ni2+>Mn2+>Mg2+/Ca2+.The corresponding CD spectra and intrinsic fluorescent emission spectra show that calcineurin A exists in different metal ion-dependent conformation states.Effects of the different concentritions of Ni2+ on activities and solution conformations of calcineurin A have been tested too.Results indicate that effects of these metal ions to activate calcineurin are due to their conformational changes.

  13. Plasma immersion ion implantation for reducing metal ion release

    Diaz, C.; Garcia, J. A.; Maendl, S.; Pereiro, R.; Fernandez, B.; Rodriguez, R. J. [Centro de Ingenieria Avanzada de Superficies AIN, 31191, Cordovilla-Pamplona (Spain); Leibniz-Institut fuer Oberflaechenmodifizierung, 04318 Leipzig (Germany); Universidad de Oviedo, Departamento Quimica Fisica y Analitica (Spain); Centro de Ingenieria Avanzada de Superficies AIN, 31191, Cordovilla-Pamplona (Spain)


    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. Conformational thermodynamics of metal-ion binding to a protein

    Das, Amit; Chakrabarti, J.; Ghosh, Mahua


    Conformational changes in proteins induced by metal-ions play extremely important role in various cellular processes and technological applications. Dihedral angles are suitable conformational variables to describe microscopic conformations of a biomacromolecule. Here, we use the histograms of the dihedral angles to study the thermodynamics of conformational changes of a protein upon metal-ion binding. Our method applied to Ca2+ ion binding to an important metalloprotein, Calmodulin, reveals different thermodynamic changes in different metal-binding sites. The ligands coordinating to Ca2+ ions also play different roles in stabilizing the metal-ion coordinated protein-structure. Metal-ion binding induce remarkable thermodynamic changes in distant part of the protein via modification of secondary structural elements.

  15. Study on the Flocculability of Metal Ions by Bacillus Mucilaginosus GY03 Strain

    连宾; 陈烨; 袁生; 朱立军; 刘丛强


    This study deals with the flocculability of two types of metal ions by Bacillus mucilaginosus GY03 Strain, with an emphasis on the influence of pH conditions, volume and time of flocculants produced by GY03 Strain on the adsorption of metal irons such as Pb+2 and Mn+2 and the capabilities of flocculants to adsorb metal ions of different concentrations. The results showed that microbial flocculants produced by Bacillus mucilaginosus GY03 Strain are highly capable of flocculating metal ions, but show different effectiveness with respect to the adsorption of Pb+2 and Mn+2. In accordance with the experimental data and actual waste-water treatment conditions, the relevant regression equation of flocculation has been deduced, which has found some application in practice. The experimental results of this study demonstrated that microbial flocculants produced by Bacillus mucilaginosus can be used to treat metallic ion-containing waste water. In practical application the volume of microbial flocculants required and flocculation conditions should be taken into comprehensive consideration in accordance with the properties of metal ions, the composition of anions and the solubility of other metals, in combination with the cost and effectiveness of flocculants to be used. Flocculant used in this experiment has the advantages of being applied over a wide range of pH values, small flocculant volume, and rapid speed of flocculation. So this kind of flocculant is within excellent prospect of application.

  16. In vitro cytotoxicity of metallic ions released from dental alloys

    Milheiro, A.; Nozaki, K.; Kleverlaan, C.J.; Muris, J.; Miura, H.; Feilzer, A.J.


    The cytotoxicity of a dental alloy depends on, but is not limited to, the extent of its corrosion behavior. Individual ions may have effects on cell viability that are different from metals interacting within the alloy structure. We aimed to investigate the cytotoxicity of individual metal ions in c

  17. Metal ion binding to peptides: Oxygen or nitrogen sites?

    Dunbar, R. C.; Polfer, N. C.; G. Berden,; Oomens, J.


    Infrared multiple-photon dissociation (IRMPD) spectroscopy was used to probe the conformations of gas-phase metal-ion complexes between a series of five metal ions and six small peptide ligands. This report is presented in recognition and tribute for the Armentrout group's long and hugely produ

  18. Metal ion binding to peptides: oxygen or nitrogen sites?

    R.C. Dunbar; N.C. Polfer; G. Berden; J. Oomens


    Infrared multiple-photon dissociation (IRMPD) spectroscopy was used to probe the conformations of gas-phase metal-ion complexes between a series of five metal ions and six small peptide ligands. This report is presented in recognition and tribute for the Armentrout group's long and hugely productive

  19. In vitro cytotoxicity of metallic ions released from dental alloys

    Milheiro, A.; Nozaki, K.; Kleverlaan, C.J.; Muris, J.; Miura, H.; Feilzer, A.J.


    The cytotoxicity of a dental alloy depends on, but is not limited to, the extent of its corrosion behavior. Individual ions may have effects on cell viability that are different from metals interacting within the alloy structure. We aimed to investigate the cytotoxicity of individual metal ions in

  20. Negative Ion Photoelectron Spectroscopy Reveals Thermodynamic Advantage of Organic Acids in Facilitating Formation of Bisulfate Ion Clusters: Atmospheric Implications

    Hou, Gao-Lei; Lin, Wei; Deng, Shihu; Zhang, Jian; Zheng, Weijun; Paesani, Francesco; Wang, Xue B.


    Recent lab and field measurements have indicated critical roles of organic acids in enhancing new atmospheric aerosol formation. Such findings have stimulated theoretical studies with the aim of understanding interaction of organic acids with common aerosol nucleation precursors like bisulfate (HSO4-). In this Letter, we report a combined negative ion photoelectron spectroscopic and theoretical investigation of molecular clusters formed by HSO4- with succinic acid (SUA, HO2C(CH2)2CO2H), HSO4-(SUA)n (n = 0-2), along with HSO4-(H2O)n and HSO4-(H2SO4)n. It is found that one SUA molecule can stabilize HSO4- by ca. 39 kcal/mol, triple the corresponding value that one water molecule is capable of (ca. 13 kcal/mol). Molecular dynamics simulations and quantum chemical calculations reveal the most plausible structures of these clusters and attribute the stability of these clusters due to formation of strong hydrogen bonds. This work provides direct experimental evidence showing significant thermodynamic advantage by involving organic acid molecules to promote formation and growth in bisulfate clusters and aerosols.

  1. Analysis of metal ion release from biomedical implants

    Ivana Dimić


    Full Text Available Metallic biomaterials are commonly used for fixation or replacement of damaged bones in the human body due to their good combination of mechanical properties. The disadvantage of metals as implant materials is their susceptibility to corrosion and metal ion release, which can cause serious health problems. In certain concentrations metals and metal ions are toxic and their presence can cause diverse inflammatory reactions, genetic mutations or even cancer. In this paper, different approaches to metal ion release examination, from biometallic materials sample preparation to research results interpretation, will be presented. An overview of the analytical techniques, used for determination of the type and concentration of released ions from implants in simulated biofluids, is also given in the paper.

  2. DNA as sensors and imaging agents for metal ions.

    Xiang, Yu; Lu, Yi


    Increasing interest in detecting metal ions in many chemical and biomedical fields has created demands for developing sensors and imaging agents for metal ions with high sensitivity and selectivity. This review covers recent progress in DNA-based sensors and imaging agents for metal ions. Through both combinatorial selection and rational design, a number of metal-ion-dependent DNAzymes and metal-ion-binding DNA structures that can selectively recognize specific metal ions have been obtained. By attachment of these DNA molecules with signal reporters such as fluorophores, chromophores, electrochemical tags, and Raman tags, a number of DNA-based sensors for both diamagnetic and paramagnetic metal ions have been developed for fluorescent, colorimetric, electrochemical, and surface Raman detection. These sensors are highly sensitive (with a detection limit down to 11 ppt) and selective (with selectivity up to millions-fold) toward specific metal ions. In addition, through further development to simplify the operation, such as the use of "dipstick tests", portable fluorometers, computer-readable disks, and widely available glucose meters, these sensors have been applied for on-site and real-time environmental monitoring and point-of-care medical diagnostics. The use of these sensors for in situ cellular imaging has also been reported. The generality of the combinatorial selection to obtain DNAzymes for almost any metal ion in any oxidation state and the ease of modification of the DNA with different signal reporters make DNA an emerging and promising class of molecules for metal-ion sensing and imaging in many fields of applications.


    XiwenWang; HuaiyuZhan; WeiHe


    The effects of five metal ions(Fe-'~,Ca-~*,Mg2*,Mn-'-"Cu2") on ABTS oxidation catalyzed by laccase werestudied under condition of pH=4.5 byspectrophotometer. The results show that Fe2+ ionhas obvious effect on the activity and the nature ofinhibition is competitive type. It is found that theinhibition is realized through the reduction Fe2+ ion. Other metal ions have slight influence onlaccase activity.


    Ye, Juanying; Zhang, Xumin; Young, Clifford

      Introduction Immobilized metal ion affinity chromatography (IMAC) is a widely used technique for phosphopeptide enrichment prior to mass spectrometry. Fe(III)-IMAC is based on the strong affinity between positively charged metal ions (Fe(III)) and negatively charged phosphate groups. Many reports...... that highly selective enrichment can be achieved by the improved method even when using highly diluted phosphopeptide samples in a background of peptides (1:1000). The improved method also proved to be advantageous in minimizing sample loss. The explanation of the improvement might result from the enhanced...

  5. Oxidation of cyclohexane catalyzed by metal-ion-exchanged zeolites.

    Sökmen, Ilkay; Sevin, Fatma


    The ion-exchange rates and capacities of the zeolite NaY for the Cu(II), Co(II), and Pb(II) metal ions were investigated. Ion-exchange equilibria were achieved in approximately 72 h for all the metal ions. The maximum ion exchange of metal ions into the zeolite was found to be 120 mg Pb(II), 110 mg Cu(II), and 100 mg Co(II) per gram of zeolite NaY. It is observed that the exchange capacity of a zeolite varies with the exchanged metal ion and the amount of metal ions exchanged into zeolite decreases in the sequence Pb(II) > Cu(II) > Co(II). Application of the metal-ion-exchanged zeolites in oxidation of cyclohexane in liquid phase with visible light was examined and it is observed that the order of reactivity of the zeolites for the conversion of cyclohexane to cyclohexanone and cyclohexanol is CuY > CoY > PbY. It is found that conversion increases by increase of the empty active sites of a zeolite and the formation of cyclohexanol is favored initially, but the cyclohexanol is subsequently converted to cyclohexanone.

  6. The development and advantages of helium ion microscopy for the study of block copolymer nanopatterns

    Bell, Alan P.; Senthamaraikannan, Ramsankar; Ghoshal, Tandra; Chaudhari, Atul; Leeson, Michael; Morris, Mick A.


    Helium ion microscopy (HIM) has been used to study nanopatterns formed in block copolymer (BCP) thin films. Owing to its' small spot size, minimal forward scattering of the incident ion and reduced velocity compared to electrons of comparable energy, HIM has considerable advantages and provides pattern information and resolution not attainable with other commercial microscopic techniques. In order to realize the full potential of BCP nanolithography in producing high density ultra-small features, the dimensions and geometry of these BCP materials will need to be accurately characterized through pattern formation, development and pattern transfer processes. The preferred BCP pattern inspection techniques (to date) are principally atomic force microscopy (AFM) and secondary electron microscopy (SEM) but suffer disadvantages in poor lateral resolution (AFM) and the ability to discriminate individual polymer domains (SEM). SEM suffers from reduced resolution when a more surface sensitive low accelerating voltage is used and low surface signal when a high accelerating voltage is used. In addition to these drawbacks, SEM can require the use of a conductive coating on these insulating materials and this reduces surface detail as well as increasing the dimensions of coated features. AFM is limited by the dimensions of the probe tip and a skewing of lateral dimension results. This can be eliminated through basic geometry for large sparse features, but when dense small features need to be characterized AFM lacks reliability. With this in mind, BCP inspection by HIM can offer greater insight into block ordering, critical dimensions and, critically, line edge roughness (LER) a critical parameter whose measurement is well suited to HIM because of its' enhanced edge contrast. In this work we demonstrate the resolution capabilities of HIM using various BCP systems (lamellar and cylinder structures). Imaging of BCP patterns of low molecular weight (MW)/low feature size which

  7. Preparation of Dithizone Functionalized Polystyrene for Detecting Heavy Metal Ion

    Shin, Hyeon Ho; Kim, Younghun [Kwangwoon University, Seoul (Korea, Republic of)


    Colorimetric sensors were usually used to detect specific metal ions using selective color change of solutions. While almost organic dye in colorimetric sensors detected single molecule, dithizone (DTZ) solution could be separately detected above 5 kinds of heavy metal ions by the change of clear color. Namely, DTZ could be used as multicolorimetric sensors. However, DTZ was generally used as aqueous type and paper/pellet-type DTZ was not reported yet. Therefore, in this work, polystyrene (PS) was prepared to composite with DTZ and then DTZ/PS pellet was obtained, which was used to selectively detect 10 kinds of heavy metal ions. When 10 ppm of Hg and Co ions was exposed in DTZ/PS pellets, clear color change was revealed. It is noted that DTZ/PS pellet could be used in detecting of heavy metal ion as dry type.

  8. Catalysis using hydrous metal oxide ion exchanges

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


    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.

  9. Catalysis using hydrous metal oxide ion exchangers

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


    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.

  10. Metallic ion release from biocompatible cobalt-based alloy

    Dimić Ivana D.


    Full Text Available Metallic biomaterials, which are mainly used for the damaged hard tissue replacements, are materials with high strength, excellent toughness and good wear resistance. The disadvantages of metals as implant materials are their susceptibility to corrosion, the elastic modulus mismatch between metals and human hard tissues, relatively high density and metallic ion release which can cause serious health problems. The aim of this study was to examine metallic ion release from Co-Cr-Mo alloy in artificial saliva. In that purpose, alloy samples were immersed into artificial saliva with different pH values (4.0, 5.5 and 7.5. After a certain immersion period (1, 3 and 6 weeks the concentrations of released ions were determined using Inductively Coupled Plasma - Mass Spectrophotometer (ICP-MS. The research findings were used in order to define the dependence between the concentration of released metallic ions, artificial saliva pH values and immersion time. The determined released metallic ions concentrations were compared with literature data in order to describe and better understand the phenomenon of metallic ion release from the biocompatible cobalt-based alloy. [Projekat Ministarstva nauke Republike Srbije, br. III 46010 i br. ON 174004

  11. Bioinorganic Chemistry of the Alkali Metal Ions.

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


    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.

  12. Adsorption of rare earth metal ion by algae. Sorui ni yoru kidorui ion no kyuchaku

    Kuwabara, T.; Yazawa, A. (Miyagi National College of Technology, Miyagi (Japan))


    This paper reports the result of investigations on adsorption of rare earth metal ion by using algae, and adsorption of different metal ions by using egg white and soy bean protein. Rare earth metal ion is adsorbed at a considerably high rate with alga powder of different kinds. The adsorption has been judged to be cation exchange reactive adsorption, while with use of spirulina and chlorella a maximum value of adsorption rate has been observed at pH from 3 to 4.5. Therefore, selective adsorption and separation of metal ions other than rare earth metal ion has become possible. When the blue pigment extracted from spirulina, the spirulina blue, is used, the rare earth metal ion had its selective adsorption and separation performance improved higher than using spirulina itself at pH from 3 to 4.5. As a result of adsorption experiment using egg white and soy bean protein, it has been found that the metal ion adsorption behavior of the spirulina blue depends on coagulative action of protein structure to some extent. However, the sharp selective adsorption performance on rare earth metal ion due to particular pH strength has been found because of actions unique to the pigment structure of phycocyanin, a major component in the spirulina blue. 7 refs., 19 figs.

  13. Porous metal oxide microspheres from ion exchange resin

    Picart, S.; Parant, P.; Caisso, M.; Remy, E.; Mokhtari, H.; Jobelin, I.; Bayle, J. P.; Martin, C. L.; Blanchart, P.; Ayral, A.; Delahaye, T.


    This study is devoted to the synthesis and the characterization of porous metal oxide microsphere from metal loaded ion exchange resin. Their application concerns the fabrication of uranium-americium oxide pellets using the powder-free process called Calcined Resin Microsphere Pelletization (CRMP). Those mixed oxide ceramics are one of the materials envisaged for americium transmutation in sodium fast neutron reactors. The advantage of such microsphere precursor compared to classical oxide powder is the diminution of the risk of fine dissemination which can be critical for the handling of highly radioactive powders such as americium based oxides and the improvement of flowability for the filling of compaction chamber. Those millimetric oxide microspheres incorporating uranium and americium were synthesized and characterizations showed a very porous microstructure very brittle in nature which occurred to be adapted to shaping by compaction. Studies allowed to determine an optimal heat treatment with calcination temperature comprised between 700-800 °C and temperature rate lower than 2 °C/min. Oxide Precursors were die-pressed into pellets and then sintered under air to form regular ceramic pellets of 95% of theoretical density (TD) and of homogeneous microstructure. This study validated thus the scientific feasibility of the CRMP process to prepare bearing americium target in a powder free manner.

  14. Synthesis of Novel Metal Ion Sensors Based on DNA-Metal Interactions

    Akira Ono; Shiqi Cao; Humika Togashi; Yoko Miyake


    @@ 1Introduction The interactions of metal ions with nucleic acids, nucleosides, and nucleo-bases have been extensively investigated[1,2]. We have reported that thymine-thymine (T-T) and cytosine-cytosine (C- C) miss base pairs in DNA duplexes highly selectively capture HgⅡ ion and Ag Ⅰ ion, which result in formations of metal-mediated base pairs, T-HgⅡ -T and C-AgⅠ -C, in duplexes[3]. The phenomenon is expected to be useful for a variety of studies such as synthesis of nano-wires containing metal ions, developing metal-ion sensing methods, etc.Here, we report novel oligodeoxyribonucleotide (ODN)-based sensors that detect HgⅡ ions and AgⅠ ions in aqueous solutions.

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

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


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


    Xiwen Wang; Huaiyu Zhan; Wei He


    The effects of five metal ions(Fe2+、Ca2+、Mg2+、Mn2+、Cu2+) on ABTS oxidation catalyzed by laccase were studied under condition of pH=4.5 by spectrophotometer. The results show that Fe2+ ion has obvious effect on the activity and the nature of inhibition is competitive type. It is found that the inhibition is realized through the reduction Fe2+ ion. Other metal ions have slight influence on laccase activity.


    Pingping Su,


    Full Text Available Sorption of metal ions from aqueous solutions to birch wood and spruce heartwood and sapwood has been studied. Functional groups in wood were determined by acid-base titrations. The sorption of metal ions to wood of the different tree species was investigated by a column chromatographic technique. The mechanism of sorption is mainly ion exchange by complexation of metal ions to the functional groups, e.g. carboxyl groups and phenolic hydroxyl groups, in the wood phase. By combination of the sorption experiments with four different metal ion mixtures, the following affinity order was established for spruce sapwood particles: Fe3+>>Pb2+>>Cu2+>>Fe2+>Cd2+>Zn2+>Ni2+>Mn2+≥Ca2+≥Sr2+≥Ba2+>>Mg2+>>K+>Na+≈Li+. For all three types of stemwood studied, the affinity orders were almost the same. The ion exchange properties of wood were comparable to those of a weakly acid cation exchanger. The affinity order obtained for the synthetic resin was quite similar to the order given above for wood. The metal sorption properties of wood materials imply that they could be a potential material for removal of metal ions from aqueous solutions.

  18. Advantage of spatial map ion imaging in the study of large molecule photodissociation.

    Lee, Chin; Lin, Yen-Cheng; Lee, Shih-Huang; Lee, Yin-Yu; Tseng, Chien-Ming; Lee, Yuan-Tseh; Ni, Chi-Kung


    The original ion imaging technique has low velocity resolution, and currently, photodissociation is mostly investigated using velocity map ion imaging. However, separating signals from the background (resulting from undissociated excited parent molecules) is difficult when velocity map ion imaging is used for the photodissociation of large molecules (number of atoms ≥ 10). In this study, we used the photodissociation of phenol at the S1 band origin as an example to demonstrate how our multimass ion imaging technique, based on modified spatial map ion imaging, can overcome this difficulty. The photofragment translational energy distribution obtained when multimass ion imaging was used differed considerably from that obtained when velocity map ion imaging and Rydberg atom tagging were used. We used conventional translational spectroscopy as a second method to further confirm the experimental results, and we conclude that data should be interpreted carefully when velocity map ion imaging or Rydberg atom tagging is used in the photodissociation of large molecules. Finally, we propose a modified velocity map ion imaging technique without the disadvantages of the current velocity map ion imaging technique.

  19. Designer ligands: The search for metal ion selectivity

    Perry T. Kaye


    Full Text Available The paper reviews research conducted at Rhodes University towards the development of metal-selective ligands. The research has focused on the rational design, synthesis and evaluation of novel ligands for use in the formation of copper complexes as biomimetic models of the metalloenzyme, tyrosinase, and for the selective extraction of silver, nickel and platinum group metal ions in the presence of contaminating metal ions. Attention has also been given to the development of efficient, metal-selective molecular imprinted polymers.

  20. Metal ion removal from aqueous solution using physic seed hull.

    Mohammad, Masita; Maitra, Saikat; Ahmad, Naveed; Bustam, Azmi; Sen, T K; Dutta, Binay K


    The potential of physic seed hull (PSH), Jantropha curcas L. as an adsorbent for the removal of Cd(2+) and Zn(2+) metal ions from aqueous solution has been investigated. It has been found that the amount of adsorption for both Cd(2+) and Zn(2+) increased with the increase in initial metal ions concentration, contact time, temperature, adsorbent dosage and the solution pH (in acidic range), but decreased with the increase in the particle size of the adsorbent. The adsorption process for both metal ions on PSH consists of three stages-a rapid initial adsorption followed by a period of slower uptake of metal ions and virtually no uptake at the final stage. The kinetics of metal ions adsorption on PSH followed a pseudo-second-order model. The adsorption equilibrium data were fitted in the three adsorption isotherms-Freundlich, Langmuir and Dubinin-Radushkevich isotherms. The data best fit in the Langmuir isotherm indication monolayer chemisorption of the metal ions. The adsorption capacity of PSH for both Zn(2+) and Cd(2+) was found to be comparable with other available adsorbents. About 36-47% of the adsorbed metal could be leached out of the loaded PSH using 0.1M HCl as the eluting medium.

  1. Antimicrobial Effect of Metal Ions Substitution to HAp, Zeolite

    Kim, Y. J.; Kim, S. B.; Cho, S. B; Cho, K. J.; Lee, T. H. [Pai Chai University, Taejeon (Korea); Kim, T. N. [Korea Institute of Geoscience and Mineral Resources, Taejeon (Korea)


    Generally, hydroxyapatite(HAp), zeolite, carbon molecular sieve, activated carbon and alumina are used as heavy metal ions adsorption materials. Among those adsorption materials, HAp which has good positive ion-exchange ability with metal ion, and zeolite are utilized in wastewater treatment. Most of water pollutions are caused by hazardous heavy metals ions as well as bacteria in waste water. In this study, a adsorption materials (HAp and zeolite) are ion-exchanged with a well known antimicrobial metal ions, such as Ag{sup +}, Cu{sup 2+}, and Zn{sup 2+}, in order to give a adsorption of heavy metal ions and a killing effects of bacteria. The antimicrobial effects of adsorption materials are observed using by E. Coli. The results show that there is a complete antimicrobial effect in the adsorption materials with Ag{sup +} at the concentration of 1x10{sup -4}cell/ml of E. Coli until 24 hours. However, there is not good antimicrobial effects in the adsorption materials with Cu{sup 2+} and Zn{sup 2+} substitution. Feng et. al. showed the denaturation effects of silver ions which induces the condensed DNA molecules and losing their replication abilities. (author). 13 refs., 6 figs., 2 tabs.

  2. Experimental Study on Surface Reactions of Heavy Metal Ions With Quartz—Aqueous Ion Concentration Dependence

    吴宏海; 吴大清; 等


    Adsorption of divalent metal ions,including Cu2+,Pb2+,Zn2+,Cd2+ and Ni2+,on quartz surface was measured as a function of metal ion concentration at 30℃under condi tions of solution pH=6.5 and ion strength I=0.1mol/L.Results of the experimental measuements can be described very well by adsorption isoterm dquations of Freudlich.The correlation coefficients(r)of adsorption isotherm lines are>0.96.Moreover,the exprimental data were interpreted on the basis of surface complexation model.Te experimental results showed that the monodentate-coordinated metal ion surface complex species(SOM+)are predominant over the bidentate-coordinated metal ion surface complex species[(SO)2M]formed only by the ions Cu2+,Zn2+ and Ni2+,And the relevant apparent surface complexation constants are lgKM=2.2-3.3 in order of KCd≥KPb>KZn>KNi≥KCu,and lgβM=5.8-6.8 in oder of βNi>βZn>βCu.Therefore,the reactive ability of the ions onto mineral surface of quartz follows the order of Cd>Pb>Zn>Ni>Cu under the above-mentioned solution conditions.The apparent surface complexation constants,influenced by the surface potential,surface species and hydrolysis of metal ions,depend mainly on the Born solvation coefficeient of the metal ions.

  3. Kinetic Analysis of Metal Ions: An Undergraduate Laboratory Experiment.

    Williams, Kathryn R.


    Reports on the adaptation of a kinetic method of analysis of metal ions for use in an undergraduate teaching laboratory. Background information, procedures used, and analysis of typical results obtained are provided. (JN)

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

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


    .... 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...



    Soc. Ethiop. 2003, 17(2), 155-165. ISSN 1011-3924 ... Cassava starch formed Werner-type complexes with ions of metals from the transition groups. This was proven by conductivity and electron paramagnetic resonance measurements.

  6. Metal Ion Selectivity of Kojate Complexes: A Theoretical Study

    Sarita Singh


    Full Text Available Density functional calculations have been performed on four-coordinate kojate complexes of selected divalent metal ions in order to determine the affinity of the metal ions for the kojate ion. The complexation reactions are characterized by high energies, showing that they are highly exothermic. It is found that Ni(II exhibits the highest affinity for the kojate ion, and this is attributed to the largest amount of charge transfer from the ligand to the metal ion. The Ni(II complex has distorted square planar structure. The HOMOs and LUMOs of the complexes are also discussed. All complexes display a strong band at ~1500 cm−1 corresponding to the stretching frequency of the weakened carbonyl bond. Comparison of the complexation energies for the two steps shows that most of the complexation energy is realized in the first step. The energy released in the second step is about one-third that of the first step.

  7. Smart textile device using ion polymer metal compound.

    Nakamura, Taro; Ihara, Tadashi


    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.

  8. Isothermal Titration Calorimetry Measurements of Metal Ions Binding to Proteins.

    Quinn, Colette F; Carpenter, Margaret C; Croteau, Molly L; Wilcox, Dean E


    ITC measurements involving metal ions are susceptible to a number of competing reactions (oxidation, precipitation, and hydrolysis) and coupled reactions involving the buffer and protons. Stabilization and delivery of the metal ion as a well-defined and well-characterized complex with the buffer, or a specific ligand, can suppress undesired solution chemistry and, depending on the stability of the metal complex, allow accurate measurements of higher affinity protein-binding sites. This requires, however, knowledge of the thermodynamics of formation of the metal complex and accounting for its contribution to the experimentally measured values (KITC and ΔHITC) through a post hoc analysis that provides the condition-independent binding thermodynamics (K, ΔG(o), ΔH, ΔS, and ΔCP). This analysis also quantifies the number of protons that are displaced when the metal ion binds to the protein. © 2016 Elsevier Inc. All rights reserved.

  9. Erosion yield of metal surface under ion pulsed irradiation

    Krivobokov, Valery; Stepanova, Olga, E-mail:; Yuryeva, Alena


    The paper is devoted to the study of erosion processes on a metal surface (Ag, Ni, Cu, W) under argon ion bombardment. The erosion yields including the sputtered and evaporated particles have been calculated for a wide range of the initial ion energy (1–1000 keV). They are revealed to reach the values from units to 10{sup 4} atom/ion under a pulsed ion beam with the power density of 10{sup 2}–10{sup 10} W/cm{sup 2}. The ion beam and target parameters are shown to influence on the erosion intensity.

  10. Functional identification of catalytic metal ion binding sites within RNA.

    James L Hougland


    Full Text Available 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.

  11. Laccase Immobilization by Chelated Metal Ion Coordination Chemistry

    Qingqing Wang


    Full Text Available In this work, amidoxime polyacrylonitrile (AOPAN nanofibrous membrane was prepared by a reaction between PAN nanofibers and hydroxylamine hydrochloride. The AOPAN nanofibrous membranes were used for four metal ions (Fe3+, Cu2+, Ni2+, Cd2+ chelation under different conditions. Further, the competition of different metal ions coordinating with AOPAN nanofibrous membrane was also studied. The AOPAN chelated with individual metal ion (Fe3+, Cu2+, Ni2+, Cd2+ and also the four mixed metal ions were further used for laccase (Lac immobilization. Compared with free laccase, the immobilized laccase showed better resistance to pH and temperature changes as well as improved storage stability. Among the four individual metal ion chelated membranes, the stability of the immobilized enzymes generally followed the order as Fe–AOPAN–Lac > Cu–AOPAN–Lac > Ni–AOPAN–Lac > Cd–AOPAN–Lac. In addition, the immobilized enzyme on the carrier of AOPAN chelated with four mixed metal ions showed the best properties.

  12. metal ion sequestration: an exciting dimension for molecularly ...

    The use of a tight binding macrocyclic ligand to complex a metal ion so that this serves as receptee on ... nickel(lI) ion whose chemistry is a reasonable substitute for many of the common environmentally .... certain soil bacteria secrete powerful.

  13. Metal ion trend may be more predictive for malfunctioning metal-on-metal implants than a single measurement

    Smolders, J.M.; Hol, A.; Susante, J.L.C. van


    Forty-eight unilateral hip resurfacing arthroplasty patients were evaluated for cobalt and chromium levels. The metal ion trend of 42 well-functioning patients was compared with six sub-optimal functioning patients. Median metal ion levels were significantly higher for the sub-optimal group. For the

  14. In Vivo Metal Ion Imaging Using Fluorescent Sensors.

    Van de Bittner, Genevieve C; Hirayama, Tasuku


    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.

  15. Detection of trace heavy metal ions in water by nanostructured porous Si biosensors.

    Shtenberg, Giorgi; Massad-Ivanir, Naama; Segal, Ester


    A generic biosensing platform, based on nanostructured porous Si (PSi), Fabry-Pérot thin films, for label-free monitoring of heavy metal ions in aqueous solutions by enzymatic activity inhibition, is described. First, we show a general detection assay by immobilizing horseradish peroxidase (HRP) within the oxidized PSi nanostructure and monitor its catalytic activity in real time by reflective interferometric Fourier transform spectroscopy. Optical studies reveal the high specificity and sensitivity of the HRP-immobilized PSi towards three metal ions (Ag(+) > Pb(2+) > Cu(2+)), with a detection limit range of 60-120 ppb. Next, we demonstrate the concept of specific detection of Cu(2+) ions (as a model heavy metal) by immobilizing Laccase, a multi-copper oxidase, within the oxidized PSi. The resulting biosensor allows for specific detection and quantification of copper ions in real water samples by monitoring the Laccase relative activity. The optical biosensing results are found to be in excellent agreement with those obtained by the gold standard analytical technique (ICP-AES) for all water samples. The main advantage of the presented biosensing concept is the ability to detect heavy metal ions at environmentally relevant concentrations using a simple and portable experimental setup, while the specific biosensor design can be tailored by varying the enzyme type.



    The interactions between metal ions such as Zn2+, Pb2+, Mn2+, Hg2+, Cd2+, Ni2+ and chitosan have been investigated using the model cluster model method and density functional method. Full optimization and frequency analysis of all cluster models have been performed employing B3LYP hybrid method at 3-21G basis set level except metal ions which were invoked to use effective core potential (ECP) method. The energy changes, and the main structural parameters have been obtained during the theoretical study of the adsorption of metal ions on the chitosan. The calculations showed that the coordination modes of metal ions with chitosan models were different, the geometries of Mn2+, Zn2+, Cd2+, Hg2+, Pb2+ ions coordinated with two nitrogen atoms and two oxygen atoms were distorted tetrahedral, while the square planar structure of Ni2+ coordinated two nitrogen atoms and two oxygen atoms was observed. The heat of reaction between six metal ions and chitosan models showed the order: Mn2+ >Ni2+ >Zn2+ >Pb2+ >Hg2+ >Cd2+, this suggested that the coordination strength of Mn2+ >Ni2+ >Zn2+ >Pb2+ >Hg2+ >Cd2+.

  17. Hall transport of divalent metal ion modified DNA lattices

    Dugasani, Sreekantha Reddy; Lee, Keun Woo; Yoo, Sanghyun; Gnapareddy, Bramaramba; Bashar, Saima; Park, Sung Ha, E-mail: [Department of Physics and Sungkyunkwan Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Kim, Si Joon; Jung, Joohye; Jung, Tae Soo; Kim, Hyun Jae, E-mail: [School of Electrical and Electronic Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of)


    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.

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

    Yushkov, G. Yu., E-mail:; Nikolaev, A. G.; Frolova, V. P. [High Current Electronics Institute, Siberian Branch of the Russian Academy of Science, Tomsk 634055 (Russian Federation); Oks, E. M. [High Current Electronics Institute, Siberian Branch of the Russian Academy of Science, Tomsk 634055 (Russian Federation); Tomsk State University of Control System and Radioelectronics, Tomsk 634050 (Russian Federation)


    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.

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

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


    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.

  20. Synthesis and Characteristics of A Novel Heavy Metal Ions Chelator

    LIU Zhuannian; SONG Yejing; HAN Xiaogang


    Polyacrylamide-urea-sulfanilamide(PUS) was prepared as a novel heavy metal ions chelator and successfully used to simultaneously remove heavy metals from wastewater effluents.The effects of reaction parameters (sodium hydroxide,material ratio,temprature and contact time) were monitored to specify the best synthesis conditions.PUS was chemically characterized by means of infrared spectroscopy (FTIR) and ultraviolet-visible (UV-Vis).The simultaneous chelation performance of PUS towards selected heavy metals ions,Ni2+,Cu2+,Pb2+,Zn2+,Cd2+ was discussed,showing that Ni2+,Cu2+,Pb2+,Zn2+ could be better chelated.It is indicated that the synthesized PUS is a potential remediation material when used for the treatment of wastewater containing metal ions.

  1. Rational design of metal oxide nanocomposite anodes for advanced lithium ion batteries

    Li, Yong; Yu, Shenglan; Yuan, Tianzhi; Yan, Mi; Jiang, Yinzhu


    Metal-oxide anodes represent a significant future direction for advanced lithium ion batteries. However, their practical applications are still seriously hampered by electrode disintegration and capacity fading during cycling. Here, we report a rational design of 3D-staggered metal-oxide nanocomposite electrode directly fabricated by pulsed spray evaporation chemical vapor deposition, where various oxide nanocomponents are in a staggered distribution uniformly along three dimensions and across the whole electrode. Such a special design of nanoarchitecture combines the advantages of nanoscale materials in volume change and Li+/electron conduction as well as uniformly staggered and compact structure in atom migration during lithiation/delithiation, which exhibits high specific capacity, good cycling stability and excellent rate capability. The rational design of metal-oxide nanocomposite electrode opens up new possibilities for high performance lithium ion batteries.

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

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


    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.

  3. Single site porphyrine-like structures advantages over metals for selective electrochemical CO2 reduction

    Bagger, Alexander; Ju, Wen; Varela, Ana Sofia


    Currently, no catalysts are completely selective for the electrochemical CO2 Reduction Reaction (CO2RR). Based on trends in density functional theory calculations of reaction intermediates we find that the single metal site in a porphyrine-like structure has a simple advantage of limiting the com...

  4. Therapeutic redistribution of metal ions to treat Alzheimer's disease.

    Crouch, Peter J; Barnham, Kevin J


    Currently, therapeutics that modify Alzheimer's disease (AD)are not available. Increasing age is the primary risk factor for AD and due to an aging global population the urgent need for effective therapeutics increases every year. This Account presents the development of an AD treatment strategy that incorporates diverse compounds with a common characteristic: the ability to redistribute metal ions within the brain. Central to cognitive decline in AD is the amyloid-β peptide (Aβ) that accumulates in the AD brain. A range of therapeutic strategies have been developed based on the premise that decreasing the brain Aβ burden will attenuate the severity of the disease symptoms. Unfortunately these treatments have failed to show any positive outcomes in large-scale clinical trials, raising many questions regarding whether therapeutics for AD can rely solely on decreasing Aβ levels. An alternate strategy is to target the interaction between Aβ and metal ions using compounds with the potential to redistribute metal ions within the brain. The original rationale for this strategy came from studies showing that metal ions promote Aβ toxicity and aggregation. In initial studies using the prototype metal-chelating compound clioquinol (CQ), CQ prevented Aβ toxicity in vitro, out-competed Aβ for metal ions without affecting the activity of metal-dependent enzymes, and attenuated the rate of cognitive decline in AD subjects in a small phase II clinical trial. All these outcomes were consistent with the original hypothesized mechanism of action for CQ where prevention or reversal of the extracellular Aβ-metal interactions could prevent Aβ toxicity. Soon after the completion of these studies, a new body of work began to suggest that this hypothesized mechanism of action for CQ was simplistic and that other factors were also important for the positive therapeutic outcomes. Perhaps most significantly, it was shown that after CQ sequesters metal ions the neutral CQ-metal

  5. Auger neutralization rates of multiply charged ions near metal surfaces

    Nedeljkovic, N.N.; Janev, R.K.; Lazur, V.Y.


    Transition rates for the Auger neutralization processes of multiply charged ions on metal surfaces are calculated in closed analytical form. The core potential of a multiply charged ion is represented by a pseudopotential, which accounts for the electron screening effects and allows transition to the pure Coulomb case (fully stripped ions). The relative importance of various neutralization channels in slow-ion--surface collisions is discussed for the examples of He/sup 2+/+Mo(100) and C/sup 3+/+Mo(100) collisional systems.

  6. Metal ions potentiate microglia responsiveness to endotoxin.

    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


    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.

  7. Metal ion interpretation in resurfacing versus conventional hip arthroplasty and in whole blood versus serum. How should we interpret metal ion data

    Smolders, J.M.; Bisseling, P.; Hol, A.; Straeten, C. Van Der; Schreurs, B.W.; Susante, J.L.C. van


    Metal ions generated from joint replacements are a cause for concern. There is no consensus on the best surrogate measure of metal ion exposure, and both serum and whole blood measurements are used in clinical practice. This study provides a guideline for interpretation of metal ion analysis in clin

  8. Metal ion interpretation in resurfacing versus conventional hip arthroplasty and in whole blood versus serum. How should we interpret metal ion data

    Smolders, J.M.; Bisseling, P.; Hol, A.; Straeten, C. Van Der; Schreurs, B.W.; Susante, J.L.C. van


    Metal ions generated from joint replacements are a cause for concern. There is no consensus on the best surrogate measure of metal ion exposure, and both serum and whole blood measurements are used in clinical practice. This study provides a guideline for interpretation of metal ion analysis in clin

  9. Chromosomal antioxidant genes have metal ion-specific roles as determinants of bacterial metal tolerance.

    Harrison, Joe J; Tremaroli, Valentina; Stan, Michelle A; Chan, Catherine S; Vacchi-Suzzi, Caterina; Heyne, Belinda J; Parsek, Matthew R; Ceri, Howard; Turner, Raymond J


    Microbiological metal toxicity involves redox reactions between metal species and cellular molecules, and therefore, we hypothesized that antioxidant systems might be chromosomal determinants affecting the susceptibility of bacteria to metal toxicity. Here, survival was quantified in metal ion-exposed planktonic cultures of several Escherichia coli strains, each bearing a mutation in a gene important for redox homeostasis. This characterized approximately 250 gene-metal combinations and identified that sodA, sodB, gor, trxA, gshA, grxA and marR have distinct roles in safeguarding or sensitizing cells to different toxic metal ions (Cr(2)O(7)(2-), Co(2+), Cu(2+), Ag(+), Zn(2+), AsO(2)(-), SeO(3)(2-) or TeO(3)(2-)). To shed light on these observations, fluorescent sensors for reactive oxygen species (ROS) and reduced thiol (RSH) quantification were used to ascertain that different metal ions exert oxidative toxicity through disparate modes-of-action. These oxidative mechanisms of metal toxicity were categorized as involving ROS and thiol-disulfide chemistry together (AsO(2)(-), SeO(3)(2-)), ROS predominantly (Cu(2+), Cr(2)O(7)(2-)) or thiol-disulfide chemistry predominantly (Ag(+), Co(2+), Zn(2+), TeO(3)(2-)). Corresponding to this, promoter-luxCDABE fusions showed that toxic doses of different metal ions up- or downregulate the transcription of gene sets marking distinct pathways of cellular oxidative stress. Altogether, our findings suggest that different metal ions are lethal to cells through discrete pathways of oxidative biochemistry, and moreover, indicate that chromosomally encoded antioxidant systems may have metal ion-specific physiological roles as determinants of bacterial metal tolerance.

  10. Ion conducting fluoropolymer carbonates for alkali metal ion batteries

    DeSimone, Joseph M.; Pandya, Ashish; Wong, Dominica; Balsara, Nitash P.; Thelen, Jacob; Devaux, Didier


    Liquid or solid electrolyte compositions are described that comprise a homogeneous solvent system and an alkali metal salt dissolved in said solvent system. The solvent system may comprise a fluoropolymer, having one or two terminal carbonate groups covalently coupled thereto. Batteries containing such electrolyte compositions are also described.

  11. Interactions Between Metal Ions and Carbohydrates: Coordination Behavior of D-Ribose to Lanthanide Ions

    苏允兰; 杨丽敏; 翁诗甫; 吴瑾光


    Lanthanum chloride α-D-ribopyranose pentahydrate complex was prepared and speculated its structure from the similar IR spectra of corresponding praseodymium and neodymium-D-ribose complexes, which reveal the coordination behavior of D-ribose to lanthanide ions and give us a model of the interactions between metal ions and carbohydrates.

  12. Ab Initio Molecular Dynamics Study on the Interactions between Carboxylate Ions and Metal Ions in Water.

    Mehandzhiyski, Aleksandar Y; Riccardi, Enrico; van Erp, Titus S; Trinh, Thuat T; Grimes, Brian A


    The interaction between a carboxylate anion (deprotonated propanoic acid) and the divalent Mg(2+), Ca(2+), Sr(2+), Ba(2+) metal ions is studied via ab initio molecular dynamics. The main focus of the study is the selectivity of the carboxylate-metal ion interaction in aqueous solution. The interaction is modeled by explicitly accounting for the solvent molecules on a DFT level. The hydration energies of the metal ions along with their diffusion and mobility coefficients are determined and a trend correlated with their ionic radius is found. Subsequently, a series of 16 constrained molecular dynamics simulations for every ion is performed, and the interaction free energy is obtained from thermodynamic integration of the forces between the metal ion and the carboxylate ion. The results indicate that the magnesium ion interacts most strongly with the carboxylate, followed by calcium, strontium, and barium. Because the interaction free energy is not enough to explain the selectivity of the reaction observed experimentally, more detailed analysis is performed on the simulation trajectories to understand the steric changes in the reaction complex during dissociation. The solvent dynamics appear to play an important role during the dissociation of the complex and also in the observed selectivity behavior of the divalent ions.

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

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


    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.

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

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


    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.

  15. Sensitive Determination of DNA by RLS Enhancement of Metal Ions

    Huang Jian-ping; Chen Fang; Ai Xin-ping; He Zhi-ke


    The interactions between metal ions and DNA have been studied by the resonance light scattering (RLS) spectra. In the acidic condition, the RLS signals of metal ions, especially the transition metal ions in group ⅠB and ⅡB, were increased by DNA. And it is found that the enhancement of RLS signals is linear to the concentration of DNA, so the RLS method for DNA determination was proposed in the presence of Cu2+. On the optimum conditions, the linear range and the detect limit of ctDNA is 4×10-8-4×10-6 g·5mL-1 and 1.13×10-8 g·5mL-1, respectively. The proposed method is successfully applied to determine the extracted plasmid DNA of Bacillus subtilis DB104.

  16. Determination of Some Heavy-metal-ions Using a Sulfur Ion Modified BZ Oscillating System

    Hua CHEN; Wu YANG; Hong Xia DAI; Xiao Xia WEI; Jie QU; Jin Zhang GAO


    A highly sensitive method is developed for the determination of trace amounts of some heavy metal ions in aqueous solution based on the classical Belousov-Zhabotinskii (BZ) oscillating chemical system. Introducing of S2- ion makes the new oscillating system Ce(SO4)2 - KBrO3-CH2(COOH)2 - Na2S - H2SO4 have to a high sensitivity for some heavy metal ions such as Ag+,pb2+, Hg2+, Cd2+, Cu2+and Bi3+ with detection limits down to 10-12 mol. L-1.

  17. Binding of alkali metal ions by cyclic polyethers: significance in ion transport processes.

    Izatt, R M; Rytting, J H; Nelson, D P; Haymore, B L; Christensen, J J


    Values for the formation constant (log K), the change in enthalpy (triangle upH degrees ), and the change in entropy (triangle upS degrees ) have been determined for the interaction of lithium, sodium, potassium, rubidium, and cesium ions with the two isomers of the cyclic polyether, 2,5,8,15,18,21-hexaoxatricyclo[,14)] hexacosane. The stability order of these metal ions with either isomer is identical to the permeability order for these same metal ions with the structurally related antibiotics, valinomycin and monactin.

  18. Metal ion coordination, conditional stability constants, and solution behavior of chelating surfactant metal complexes.

    Svanedal, Ida; Boija, Susanne; Almesåker, Ann; Persson, Gerd; Andersson, Fredrik; Hedenström, Erik; Bylund, Dan; Norgren, Magnus; Edlund, Håkan


    Coordination complexes of some divalent metal ions with the DTPA (diethylenetriaminepentaacetic acid)-based chelating surfactant 2-dodecyldiethylenetriaminepentaacetic acid (4-C12-DTPA) have been examined in terms of chelation and solution behavior. The headgroup of 4-C12-DTPA contains eight donor atoms that can participate in the coordination of a metal ion. Conditional stability constants for five transition metal complexes with 4-C12-DTPA were determined by competition measurements between 4-C12-DTPA and DTPA, using electrospray ionization mass spectrometry (ESI-MS). Small differences in the relative strength between the coordination complexes of DTPA and 4-C12-DTPA indicated that the hydrocarbon tail only affected the chelating ability of the headgroup to a limited extent. The coordination of Cu(2+) ions was investigated in particular, using UV-visible spectroscopy. By constructing Job's plots, it was found that 4-C12-DTPA could coordinate up to two Cu(2+) ions. Surface tension measurements and NMR diffusometry showed that the coordination of metal ions affected the solution behavior of 4-C12-DTPA, but there were no specific trends between the studied divalent metal complexes. Generally, the effects of the metal ion coordination could be linked to the neutralization of the headgroup charge of 4-C12-DTPA, and the resulting reduced electrostatic repulsions between adjacent surfactants in micelles and monolayers. The pH vs concentration plots, on the other hand, showed a distinct difference between 4-C12-DTPA complexes of the alkaline earth metals and the transition metals. This was explained by the difference in coordination between the two groups of metal ions, as predicted by the hard and soft acid and base (HSAB) theory.

  19. Nano sized carbonized waste biomass for heavy metal ion remediation

    Mahajan Garima


    Full Text Available Utilization of agricultural waste material with approach to enhance the heavy metal remediation properties by carbonizing the biomass at nano size particles has been explored in present investigation from aqueous solutions. In this study the lignocellulosic, nitrogenous agricultural waste biomass Delbergia sissoo pods (DSP has been tried for sequestering of Cd (II, Pb (II and Ni (II metal ions from aqueous solutions. Batch experiments were performed for removal of targeted metal ions keeping in consideration the preliminary affecting parameters such as effect of adsorption dose, pH, initial metal ion concentration, stirring speed and contact time. The sorption studies were analyzed by using, Freundlic isotherm and Langmuir isotherm models. The kinetics of the process was evaluated by pseudo pseudo-first order and pseudo second order kinetic models. Studies reveal that the equilibrium was achieved with in 30 min of the contact time at optimized parameters. Analytical studies of biosorbent were done by means of FT-IR, SEM and XRD. Desorption experiments were carried out using HCl solution with a view to regenerate the spent adsorbent and to recover the adsorbed metal ions.

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

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


    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.

  1. Metal-Ion Additives Reduce Thermal Expansion Of Polyimides

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


    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.

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

    Fish, D. [Lawrence Berkeley National Lab., CA (United States)


    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.

  3. Metal ions and RNA folding: a highly charged topic with a dynamic future.

    Woodson, Sarah A


    Metal ions are required to stabilize RNA tertiary structure and to begin the folding process. How different metal ions enable RNAs to fold depends on the electrostatic potential of the RNA and correlated fluctuations in the positions of the ions themselves. Theoretical models, fluorescence spectroscopy, small angle scattering and structural biology reveal that metal ions alter the RNA dynamics and folding transition states. Specifically coordinated divalent metal ions mediate conformational rearrangements within ribozyme active sites.

  4. Advantages of scanning-mode ion beam analysis for the study of Cultural Heritage

    Grassi, N.; Giuntini, L.; Mandò, P. A.; Massi, M.


    In this paper, we discuss the convenience of performing external PIXE and PIGE measurements by scanning relatively large areas (some mm2) with a beam size of the order of hundred microns, rather than performing "spot" compositional analysis. Examples of test runs on samples of archaeometric interest are presented: scanning-mode measurements of ancient inks, Roman glass and metal point drawings clearly demonstrate that using this procedure to perform IBA may become fundamental to avoid deceptive information and to obtain more reliable quantitative results.

  5. Advantages of scanning-mode ion beam analysis for the study of Cultural Heritage

    Grassi, N. [Dipartimento di Fisica dell' Universita and Istituto Nazionale di Fisica Nucleare, Sezione di Firenze, Florence (Italy)]. E-mail:; Giuntini, L. [Dipartimento di Fisica dell' Universita and Istituto Nazionale di Fisica Nucleare, Sezione di Firenze, Florence (Italy); Mando, P.A. [Dipartimento di Fisica dell' Universita and Istituto Nazionale di Fisica Nucleare, Sezione di Firenze, Florence (Italy); Massi, M. [Dipartimento di Fisica dell' Universita and Istituto Nazionale di Fisica Nucleare, Sezione di Firenze, Florence (Italy)


    In this paper, we discuss the convenience of performing external PIXE and PIGE measurements by scanning relatively large areas (some mm{sup 2}) with a beam size of the order of hundred microns, rather than performing 'spot' compositional analysis. Examples of test runs on samples of archaeometric interest are presented: scanning-mode measurements of ancient inks, Roman glass and metal point drawings clearly demonstrate that using this procedure to perform IBA may become fundamental to avoid deceptive information and to obtain more reliable quantitative results.

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

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


    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.

  7. Vitrification of ion-exchange (IEX) resins: Advantages and technical challenges

    Jantzen, C.M.; Peeler, D.K.; Cicero, C.A.


    Technologies are being developed by the US Department of Energy`s (DOE) Savannah River Site (SRS) in conjunction with the Electric Power Research Institute (EPRI) and the commercial sector to convert low-level radioactive ion exchange (IEX) resin wastes from the nuclear utilities to solid stabilized waste forms for permanent disposal. One of the alternative waste stabilization technologies is vitrification of the resin into glass. Wastes can be vitrified at elevated temperatures by thermal treatment. One alternative thermal treatment is conventional Joule heated melting. Vitrification of wastes into glass is an attractive option because it atomistically bonds both hazardous and radioactive species in the glass structure, and volume reduces the wastes by 70-80%. The large volume reductions allow for large associated savings in disposal and/or long term storage costs.

  8. Metal ion release from electric guitar strings in artificial sweat

    Rezic, Iva [Department of Applied Chemistry, Faculty of Textile Technology, University of Zagreb, Prilaz Baruna Filipovica 28a, 10000 Zagreb (Croatia)], E-mail:; Curkovic, Lidija [Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb (Croatia); Ujevic, Magdalena [Croatian Institute of Public Health, Zagreb, Croatia (Croatia)


    The aim of this study was to monitor the dissolution of metal ions from electric guitar strings. For characterization of investigated strings, two independent methods of analysis were chosen: ICP-OES and AAS. Electric guitar strings consisted of two separate parts: Sn-plated steel core wire which was hexagonal in cross section and Ni-plated steel wrap which was round in cross section. Dissolution of Ni{sup 2+}, Mn{sup 2+}, Si{sup 4+}, Sn{sup 2+} and Fe{sup 3+} ions from electric guitar strings E6 and D4 were measured as a function of time in artificial sweat solution, at temperature of 37 deg. C according to the EN 1811:1999 standard test procedure. The determination of the amount of the metal ions released in the corrosive solutions was carried out by means of inductively coupled plasma-optical emission spectroscopy (ICP-OES). The mechanism of metal ions eluted in artificial sweat is discussed. The concentrations of dissolved metal ions in corrosive solution from E6 and D4 strings are decreasing in the following order: Fe{sup 3+} > Sn{sup 2+} > Mn{sup 2+} > Si{sup 4+} > Ni{sup 2+}. Among all investigated metal ions, nickel is far the most allergenic. Since the amounts of the eluted Ni{sup 2+} did not exceed 0.5 {mu}g cm{sup -2} week{sup -1}, the investigated electric guitar strings should not induce contact dermatitis.

  9. Chromium and cobalt ion concentrations in blood and serum following various types of metal-on-metal hip arthroplasties

    Jantzen, Christopher; Jørgensen, Henrik L; Duus, Benn R


    Widely different metal ion concentrations in blood and serum have been reported with metal-on-metal (MoM) implants. We reviewed the literature on blood and serum ion concentrations of chromium (Cr) and cobalt (Co) following various MoM hip arthroplasties.......Widely different metal ion concentrations in blood and serum have been reported with metal-on-metal (MoM) implants. We reviewed the literature on blood and serum ion concentrations of chromium (Cr) and cobalt (Co) following various MoM hip arthroplasties....

  10. Metal-assisted secondary ion mass spectrometry using atomic (Ga+, In+) and fullerene projectiles.

    Delcorte, A; Yunus, S; Wehbe, N; Nieuwjaer, N; Poleunis, C; Felten, A; Houssiau, L; Pireaux, J-J; Bertrand, P


    The advantages and drawbacks of using either monatomic or buckminsterfullerene primary ions for metal-assisted secondary ion mass spectrometry (MetA-SIMS) are investigated using a series of organic samples including additive molecules, polyolefins, and small peptides. Gold deposition is mostly performed by sputter-coating, and in some cases, the results are compared to those of thermal evaporation (already used in a previous article: Delcorte, A.; Médard, N.; Bertrand, P. Anal. Chem. 2002, 74, 4955). The microstructure of the gold-covered sample surfaces is assessed by scanning and transmission electron microscopies. The merits of the different sets of experimental conditions are established via the analysis of fragment and parent-like ion yields. For most of the analyzed samples, the highest yields of fragment and parent-like ions are already reached with the sole use of C60+ projectiles. Metallization of the sample does not lead to a significant additional enhancement. For polyethylene and polypropylene, however, gold metallization associated with Ga+/In+ projectiles appears to be the only way to observe large cationized, sample-specific chain segments (m/z approximately 1000-2000). A detailed study of the polypropylene mass spectra as a function of gold coverage shows that the dynamics of yield enhancement by metal nanoparticles is strongly dependent on the choice of the projectile, e.g., a pronounced increase with Ga+ and a slow decay with C60+. The cases of Irganox 1010, a polymer antioxidant, and leucine enkephalin, a small peptide, allow us to investigate the specific influence of the experimental conditions on the emission of parent(like) ions such as M+, (M + Na)+, and (M + Au)+. The results show a dependence on both the type of sample and the considered secondary ion. Using theoretical and experimental arguments, the discussion identifies some of the mechanisms underlying the general trends observed in the results. Guidelines concerning the choice of the

  11. Neutralization by metal ions of the toxicity of sodium selenide.

    Marc Dauplais

    Full Text Available 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.

  12. Metal ion levels and revision rates in metal-on-metal hip resurfacing arthroplasty: a comparative study.

    Robinson, Patrick G; Wilkinson, Andrew J; Meek, Robert M D


    Metal-on-metal (MoM) bearings in hip surgery are related to increased blood levels of metal ions. The nature of the relationship between ion levels and failure is still not fully understood. This study compares three cohorts of patients, 120 patients in each cohort, treated with a hip resurfacing arthroplasty, grouped by brand and diameter of femoral component on average four years postoperatively: Birmingham Hip Resurfacing ≥50 mm, Durom resurfacing ≥50 mm and Durom resurfacing resurfacing than the other two cohorts (P<0.05). The large BHR and large Durom HRA had revision rates of 3.3%. The small Durom HRA had a revision rate of 8.3%. Elevated blood ion levels can indicate a failing MoM bearing. The large BHR and large Durom HRA have similar revision rates yet the large Durom HRA had significantly lower metal ion levels. When similar ion levels were reported for BHR and small Durom the latter had significantly higher revision rates. This suggests ion levels do not absolutely predict the rate of HRA failure. Since MoM generation of metal ions is not the sole reason of failure, regular clinical and radiographic follow-up should also be in place for patients with these joints.

  13. Molecular design of the microbial cell surface toward the recovery of metal ions.

    Kuroda, Kouichi; Ueda, Mitsuyoshi


    The genetic engineering of microorganisms to adsorb metal ions is an attractive method to facilitate the environmental cleanup of metal pollution and to enrich the recovery of metal ions such as rare metal ions. For the recovery of metal ions by microorganisms, cell surface design is an effective strategy for the molecular breeding of bioadsorbents as an alternative to intracellular accumulation. The cell surface display of known metal-binding proteins/peptides and the molecular design of novel metal-binding proteins/peptides have been performed using a cell surface engineering approach. The adsorption of specific metal ions is the important challenge for the practical recovery of metal ions. In this paper, we discuss the recent progress in surface-engineered bioadsorbents for the recovery of metal ions. Copyright © 2011 Elsevier Ltd. All rights reserved.

  14. Stripping chronopotentiometry for metal ion speciation analysis at a microelectrode

    Leeuwen, van H.P.; Town, R.


    The features of metal ion speciation determination by stripping chronopotentiometry (SCP) at a microelectrode are examined and compared with those of DP-SV. SCP measurements are essentially of a steady-state nature under experimentally achievable conditions and correspond to practically complete

  15. Dimeric Complexes of Tryptophan with M2+ Metal Ions

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


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

  16. Stripping chronopotentiometry for metal ion speciation analysis at a microelectrode

    Leeuwen, van H.P.; Town, R.


    The features of metal ion speciation determination by stripping chronopotentiometry (SCP) at a microelectrode are examined and compared with those of DP-SV. SCP measurements are essentially of a steady-state nature under experimentally achievable conditions and correspond to practically complete dep

  17. Lignocellulosic Wheat Straw-Derived Ion-Exchange Adsorbent for Heavy Metals Removal.

    Krishnani, K K


    The aim of this work is to develop partially delignified Ca(2+)-and-Mg(2+)-ion-exchanged product from lignocellulosic wheat straw for the removal of eight different heavy metals Pb(2+), Cd(2+), Hg(2+), Co(2+), Ni(2+), Mn(2+), Zn(2+), and Cu(2+) and for detoxification of Cr(VI). Maximum fixation capacity, pH, and initial metal concentration dependence were determined to confirm strong affinity of Pb(2+), Cd(2+), Cu(2+), Zn(2+), and Hg(2+) ions onto the product, whereas Co(2+), Ni(2+), and Mn(2+) were the least fixed. Morphology of the product characterized by scanning electron microscope showed its physical integrity. Different experimental approaches were applied to determine the role of cations such as Ca(2+), Mg(2+), and Na(+) and several functional groups present in the product in an ion exchange for the fixation of metal ions. Potentiometric titration and Scatchard and Dahlquist interpretation were employed for determination of binding site heterogeneity. Results showed strong and weak binding sites in the product. This product has advantages over other conventional processes by virtue of abundance, easy operational process, and cost reduction in waste disposal of its raw material.

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

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


    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.

  19. Chitosan Removes Toxic Heavy Metal Ions from Cigarette Mainstream Smoke

    ZHOU Wen; XU Ying; WANG Dongfeng; ZHOU Shilu


    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.

  20. Recovery of toxic metal ions from washing effluent containing excess aminopolycarboxylate chelant in solution.

    Hasegawa, Hiroshi; Rahman, Ismail M M; Nakano, Masayoshi; Begum, Zinnat A; Egawa, Yuji; Maki, Teruya; Furusho, Yoshiaki; Mizutani, Satoshi


    Aminopolycarboxylate chelants (APCs) are extremely useful for a variety of industrial applications, including the treatment of toxic metal-contaminated solid waste materials. Because non-toxic matrix elements compete with toxic metals for the binding sites of APCs, an excess of chelant is commonly added to ensure the adequate sequestration of toxic metal contaminants during waste treatment operations. The major environmental impacts of APCs are related to their ability to solubilize toxic heavy metals. If APCs are not sufficiently eliminated from the effluent, the aqueous transport of metals can occur through the introduction of APCs into the natural environment, increasing the magnitude of associated toxicity. Although several techniques that focus primarily on the degradation of APCs at the pre-release step have been proposed, methods that recycle not only the processed water, but also provide the option to recover and reuse the metals, might be economically feasible, considering the high costs involved due to the chelants used in metal ion sequestration. In this paper, we propose a separation process for the recovery of metals from effluents that contain an excess of APCs. Additionally, the option of recycling the processed water using a solid phase extraction (SPE) system with an ion-selective immobilized macrocyclic material, commonly known as a molecular recognition technology (MRT) gel, is presented. Simulated effluents containing As(V), Cd(II), Cr(III), Pb(II) or Se(IV) in the presence of APCs at molar ratios of 1:50 in H2O were studied with a flow rate of 0.2 mL min(-1). The 'captured' ions in the SPE system were quantitatively eluted with HNO3. The effects of solution pH, metal-chelant stability constants and matrix elements were assessed. Better separation performance for the metals was achieved with the MRT-SPE compared to other SPE materials. Our proposed technique offers the advantage of a non-destructive separation of both metal ions and chelants

  1. Solution NMR refinement of a metal ion bound protein using metal ion inclusive restrained molecular dynamics methods

    Chakravorty, Dhruva K.; Wang Bing [University of Florida, Department of Chemistry and the Quantum Theory Project (United States); Lee, Chul Won [Chonnam National University, Department of Chemistry (Korea, Republic of); Guerra, Alfredo J.; Giedroc, David P., E-mail: [Indiana University, Department of Chemistry (United States); Merz, Kenneth M., E-mail: [University of Florida, Department of Chemistry and the Quantum Theory Project (United States)


    Correctly calculating the structure of metal coordination sites in a protein during the process of nuclear magnetic resonance (NMR) structure determination and refinement continues to be a challenging task. In this study, we present an accurate and convenient means by which to include metal ions in the NMR structure determination process using molecular dynamics (MD) simulations constrained by NMR-derived data to obtain a realistic and physically viable description of the metal binding site(s). This method provides the framework to accurately portray the metal ions and its binding residues in a pseudo-bond or dummy-cation like approach, and is validated by quantum mechanical/molecular mechanical (QM/MM) MD calculations constrained by NMR-derived data. To illustrate this approach, we refine the zinc coordination complex structure of the zinc sensing transcriptional repressor protein Staphylococcus aureus CzrA, generating over 130 ns of MD and QM/MM MD NMR-data compliant sampling. In addition to refining the first coordination shell structure of the Zn(II) ion, this protocol benefits from being performed in a periodically replicated solvation environment including long-range electrostatics. We determine that unrestrained (not based on NMR data) MD simulations correlated to the NMR data in a time-averaged ensemble. The accurate solution structure ensemble of the metal-bound protein accurately describes the role of conformational sampling in allosteric regulation of DNA binding by zinc and serves to validate our previous unrestrained MD simulations of CzrA. This methodology has potentially broad applicability in the structure determination of metal ion bound proteins, protein folding and metal template protein-design studies.

  2. Metal ion levels and lymphocyte counts

    Penny, Jeannette Ø; Varmarken, Jens-Erik; Ovesen, Ole


    . RESULTS: The T-lymphocyte counts for both implant types declined over the 2-year period. This decline was statistically significant for CD3(+)CD8(+) in the THA group, with a regression coefficient of -0.04 × 10(9)cells/year (95% CI: -0.08 to -0.01). Regression analysis indicated a depressive effect...... of cobalt ions in particular on T-cells with 2-year whole-blood cobalt regression coefficients for CD3+ of -0.10 (95% CI: -0.16 to -0.04) × 10(9) cells/parts per billion (ppb), for CD3+CD4+ of -0.06 (-0.09 to -0.03) × 10(9) cells/ppb, and for CD3(+)CD8(+) of -0.02 (-0.03 to -0.00) × 10(9) cells/ppb...

  3. Ion conducting polymers and polymer blends for alkali metal ion batteries

    DeSimone, Joseph M.; Pandya, Ashish; Wong, Dominica; Vitale, Alessandra


    Electrolyte compositions for batteries such as lithium ion and lithium air batteries are described. In some embodiments the compositions are liquid compositions comprising (a) a homogeneous solvent system, said solvent system comprising a perfluropolyether (PFPE) and polyethylene oxide (PEO); and (b) an alkali metal salt dissolved in said solvent system. In other embodiments the compositions are solid electrolyte compositions comprising: (a) a solid polymer, said polymer comprising a crosslinked product of a crosslinkable perfluropolyether (PFPE) and a crosslinkable polyethylene oxide (PEO); and (b) an alkali metal ion salt dissolved in said polymer. Batteries containing such compositions as electrolytes are also described.

  4. Development of a four-zone carousel process packed with metal ion-imprinted polymer for continuous separation of copper ions from manganese ions, cobalt ions, and the constituent metal ions of the buffer solution used as eluent.

    Jo, Se-Hee; Park, Chanhun; Yi, Sung Chul; Kim, Dukjoon; Mun, Sungyong


    A three-zone carousel process, in which Cu(II)-imprinted polymer (Cu-MIP) and a buffer solution were employed as adsorbent and eluent respectively, has been developed previously for continuous separation of Cu²⁺ (product) from Mn²⁺ and Co²⁺ (impurities). Although this process was reported to be successful in the aforementioned separation task, the way of using a buffer solution as eluent made it inevitable that the product stream included the buffer-related metal ions (i.e., the constituent metal ions of the buffer solution) as well as copper ions. For a more perfect recovery of copper ions, it would be necessary to improve the previous carousel process such that it can remove the buffer-related metal ions from copper ions while maintaining the previous function of separating copper ions from the other 2 impure heavy-metal ions. This improvement was made in this study by proposing a four-zone carousel process based on the following strategy: (1) the addition of one more zone for performing the two-step re-equilibration tasks and (2) the use of water as the eluent of the washing step in the separation zone. The operating conditions of such a proposed process were determined on the basis of the data from a series of single-column experiments. Under the determined operating conditions, 3 runs of carousel experiments were carried out. The results of these experiments revealed that the feed-loading time was a key parameter affecting the performance of the proposed process. Consequently, the continuous separation of copper ions from both the impure heavy-metal ions and the buffer-related metal ions could be achieved with a purity of 91.9% and a yield of 92.8% by using the proposed carousel process based on a properly chosen feed-loading time.

  5. Ion beam mixing isotopic metal bilayers

    Fell, C.J. [Newcastle Univ., NSW (Australia). Dept. of Physics; Kenny, M.J. [CSIRO, Lindfield, NSW (Australia). Div. of Applied Physics


    In order to obtain an insight into the mechanisms of ion-solid interactions, bilayer targets can be prepared from two different isotopes. A mixing study SIMS is to be carried out using specially grown monocrystalline bilayers of {sup 58}Ni / {sup 60}Ni. An important aspect of the work is the preparation of high quality single-crystal thin films. The Ni layers will be grown on the (110) surface of pure Ni and verified for crystallinity using Reflection High-Energy Electron Diffraction and Rutherford Backscattering channelling analysis. The Pd bilayers will be grown on a Pd (100) surface. RHEED will be used to confirm the two-dimensional crystallinity of the surface before and after deposition of each layer, and channelling used to confirm bulk film crystallinity. Single crystal substrates are currently being prepared. Analysis of the Ni (110) surface using RHEED at 9 kV shows a streak spacing which corresponds to a lattice spacing of 2.47 {+-} 0.09 Angstroms. 9 refs., 1 fig.

  6. Dendrimers, mesoporous silicas and chitosan-based nanosorbents for the removal of heavy-metal ions: A review.

    Vunain, E; Mishra, A K; Mamba, B B


    The application of nanomaterials as nanosorbents in solving environmental problems such as the removal of heavy metals from wastewater has received a lot of attention due to their unique physical and chemical properties. These properties make them more superior and useful in various fields than traditional adsorbents. The present mini-review focuses on the use of nanomaterials such as dendrimers, mesoporous silicas and chitosan nanosorbents in the treatment of wastewater contaminated with toxic heavy-metal ions. Recent advances in the fabrication of these nanoscale materials and processes for the removal of heavy-metal ions from drinking water and wastewater are highlighted, and in some cases their advantages and limitations are given. These next-generation adsorbents have been found to perform very well in environmental remediation and control of heavy-metal ions in wastewater. The main objective of this review is to provide up-to-date information on the research and development in this particular field and to give an account of the applications, advantages and limitations of these particular nanosorbents in the treatment of aqueous solutions contaminated with heavy-metal ions.

  7. Optical studies of ion-beam synthesized metal alloy nanoparticles

    Magudapathy, P., E-mail:; Srivatsava, S. K.; Gangopadhyay, P.; Amirthapandian, S.; Sairam, T. N.; Panigrahi, B. K. [Materials Physics Division, Indira Gandhi Centre for Atomic Research, Kalpakkam – 603 102 India (India)


    Au{sub x}Ag{sub 1-x} alloy nanoparticles with tunable surface plasmon resonance (SPR) have been synthesized on a silica glass substrate. A small Au foil on an Ag foil is irradiated as target substrates such that ion beam falls on both Ag foil and Au foils. Silica slides are kept at an angle ∼45° with respect to the metallic foils. While irradiating the metallic foils with 100 keV Ar{sup +} ions, sputtered Au and Ag atoms get deposited on the silica-glass. In this configuration the foils have been irradiated by Ar{sup +} ions to various fluences at room temperature and the sputtered species are collected on silica slides. Formation of Au{sub x}Ag{sub 1-x} nanoparticles has been confirmed from the optical absorption measurements. With respect to the exposure area of Au and Ag foils to the ion beam, the SPR peak position varies from 450 to 500 nm. Green photoluminescence has been observed from these alloy metal nanoparticles.

  8. Peptide immobilisation on porous silicon surface for metal ions detection.

    Sam, Sabrina S; Chazalviel, Jean-Noël Jn; Gouget-Laemmel, Anne Chantal Ac; Ozanam, François F; Etcheberry, Arnaud A; Gabouze, Nour-Eddine N


    In this work, a Glycyl-Histidyl-Glycyl-Histidine (GlyHisGlyHis) peptide is covalently anchored to the porous silicon PSi surface using a multi-step reaction scheme compatible with the mild conditions required for preserving the probe activity. In a first step, alkene precursors are grafted onto the hydrogenated PSi surface using the hydrosilylation route, allowing for the formation of a carboxyl-terminated monolayer which is activated by reaction with N-hydroxysuccinimide in the presence of a peptide-coupling carbodiimide N-ethyl-N'-(3-dimethylaminopropyl)-carbodiimide and subsequently reacted with the amino linker of the peptide to form a covalent amide bond. Infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy are used to investigate the different steps of functionalization.The property of peptides to form stable complexes with metal ions is exploited to achieve metal-ion recognition by the peptide-modified PSi-based biosensor. An electrochemical study of the GlyHisGlyHis-modified PSi electrode is achieved in the presence of copper ions. The recorded cyclic voltammograms show a quasi-irreversible process corresponding to the Cu(II)/Cu(I) couple. The kinetic factors (the heterogeneous rate constant and the transfer coefficient) and the stability constant of the complex formed on the porous silicon surface are determined. These results demonstrate the potential role of peptides grafted on porous silicon in developing strategies for simple and fast detection of metal ions in solution.

  9. Peptide immobilisation on porous silicon surface for metal ions detection

    Chazalviel Jean-Noël


    Full Text Available Abstract In this work, a Glycyl-Histidyl-Glycyl-Histidine (GlyHisGlyHis peptide is covalently anchored to the porous silicon PSi surface using a multi-step reaction scheme compatible with the mild conditions required for preserving the probe activity. In a first step, alkene precursors are grafted onto the hydrogenated PSi surface using the hydrosilylation route, allowing for the formation of a carboxyl-terminated monolayer which is activated by reaction with N-hydroxysuccinimide in the presence of a peptide-coupling carbodiimide N-ethyl-N'-(3-dimethylaminopropyl-carbodiimide and subsequently reacted with the amino linker of the peptide to form a covalent amide bond. Infrared spectroscopy (FT-IR and X-ray photoelectron spectroscopy are used to investigate the different steps of functionalization. The property of peptides to form stable complexes with metal ions is exploited to achieve metal-ion recognition by the peptide-modified PSi-based biosensor. An electrochemical study of the GlyHisGlyHis-modified PSi electrode is achieved in the presence of copper ions. The recorded cyclic voltammograms show a quasi-irreversible process corresponding to the Cu(II/Cu(I couple. The kinetic factors (the heterogeneous rate constant and the transfer coefficient and the stability constant of the complex formed on the porous silicon surface are determined. These results demonstrate the potential role of peptides grafted on porous silicon in developing strategies for simple and fast detection of metal ions in solution.

  10. Peptide immobilisation on porous silicon surface for metal ions detection

    Sam, Sabrina S.; Chazalviel, Jean-Noël Jn; Gouget-Laemmel, Anne Chantal Ac; Ozanam, François F.; Etcheberry, Arnaud A.; Gabouze, Nour-Eddine N.


    In this work, a Glycyl-Histidyl-Glycyl-Histidine (GlyHisGlyHis) peptide is covalently anchored to the porous silicon PSi surface using a multi-step reaction scheme compatible with the mild conditions required for preserving the probe activity. In a first step, alkene precursors are grafted onto the hydrogenated PSi surface using the hydrosilylation route, allowing for the formation of a carboxyl-terminated monolayer which is activated by reaction with N-hydroxysuccinimide in the presence of a peptide-coupling carbodiimide N-ethyl- N'-(3-dimethylaminopropyl)-carbodiimide and subsequently reacted with the amino linker of the peptide to form a covalent amide bond. Infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy are used to investigate the different steps of functionalization. The property of peptides to form stable complexes with metal ions is exploited to achieve metal-ion recognition by the peptide-modified PSi-based biosensor. An electrochemical study of the GlyHisGlyHis-modified PSi electrode is achieved in the presence of copper ions. The recorded cyclic voltammograms show a quasi-irreversible process corresponding to the Cu(II)/Cu(I) couple. The kinetic factors (the heterogeneous rate constant and the transfer coefficient) and the stability constant of the complex formed on the porous silicon surface are determined. These results demonstrate the potential role of peptides grafted on porous silicon in developing strategies for simple and fast detection of metal ions in solution.

  11. [Applications of metal ions and their complexes in medicine I].

    Nagy, László; Csintalan, Gabriella; Kálmán, Eszter; Sipos, Pál; Szvetnik, Attila


    The "inorganic medical chemistry" is a rapidly developing field with enormous potential for applications, which offers new possibilities to the pharmaceutical industry. For example, the titanocene dichloride is already in clinical use, and antimetastatic activity of a range of Ru(III) complexes is also well established. There are ways to minimize the toxicity of Gd(III) complexes and therefore they can be safely injected as MRI contrast agents. The so called "ligand design" allows paramagnetic ions to be targeted to specific organs. Such designed ligands also enable the targeting of radiodiagnostic (99mTc) and radiotherapeutic (186Re) isotopes. There is a significant progress in understanding the coordination chemistry and biochemistry of metal ion(s) containing complexes such as Au antiarthritic and Bi antiulcer drugs. Further, currently developing areas include Mn (SOD mimics), V (insulin mimics), Ru (NO scavengers), Ln-based photosensitizers, metal-targeted organic agents and the Fe overload. The expanding knowledge of the role of metals in biochemistry is expected to provide scope for the design of new drugs in many other areas too, for example neuropharmaceutical and antiaffective agents. Progress in coordination chemistry is strongly dependent on understanding not only the thermodynamics of reactions, but also the kinetics of metal complexes under biologically relevant conditions.

  12. Polymer Catalysts Imprinted with Metal Ions as Biomimics of Metalloenzymes

    Joanna Czulak


    Full Text Available This work presents the preparation and properties of molecularly imprinted polymers (MIPs with catalytic centers that mimic the active sites of metalloenzymes. The MIP synthesis was based on suspension polymerization of functional monomers (4-vinylpyridine and acrylonitrile with trimethylolpropane trimethacrylate as a crosslinker in the presence of transition metal ions and 4-methoxybenzyl alcohol as a template. Four metal ions have been chosen for imprinting from among the microelements that are the most essential in the native enzymes: Cu2+, Co2+, Mn2+, and Zn2+. To prepare catalysts, the required loading of metal ions was obtained during sorption process. The catalysts imprinted with Cu2+, Co2+, and Zn2+ were successfully used for hydroquinone oxidation in the presence of hydrogen peroxide. The Mn2+-imprinted catalyst showed no activity due to the insufficient metal loading. Cu2+ MIP showed the highest efficiency. In case of Cu- and Co-MIP catalysts, their activity was additionally increased by the use of surface imprinting technique.

  13. New Catalytic DNA Biosensors for Radionuclides and Metal ion

    Yi Lu


    We aim to develop new DNA biosensors for simultaneous detection and quantification of bioavailable radionuclides, such as uranium, technetium, and plutonium, and metal contaminants, such as lead, chromium, and mercury. The sensors will be highly sensitive and selective. They will be applied to on-site, real-time assessment of concentration, speciation, and stability of the individual contaminants before and during bioremediation, and for long-term monitoring of DOE contaminated sites. To achieve this goal, we have employed a combinatorial method called “in vitro selection” to search from a large DNA library (~ 1015 different molecules) for catalytic DNA molecules that are highly specific for radionuclides or other metal ions through intricate 3-dimensional interactions as in metalloproteins. Comprehensive biochemical and biophysical studies have been performed on the selected DNA molecules. The findings from these studies have helped to elucidate fundamental principles for designing effective sensors for radionuclides and metal ions. Based on the study, the DNA have been converted to fluorescent or colorimetric sensors by attaching to it fluorescent donor/acceptor pairs or gold nanoparticles, with 11 part-per-trillion detection limit (for uranium) and over million fold selectivity (over other radionuclides and metal ions tested). Practical application of the biosensors for samples from the Environmental Remediation Sciences Program (ERSP) Field Research Center (FRC) at Oak Ridge has also been demonstrated.

  14. How can we take advantage of halophyte properties to cope with heavy metal toxicity in salt-affected areas?

    Lutts, Stanley; Lefèvre, Isabelle


    Background Many areas throughout the world are simultaneously contaminated by high concentrations of soluble salts and by high concentrations of heavy metals that constitute a serious threat to human health. The use of plants to extract or stabilize pollutants is an interesting alternative to classical expensive decontamination procedures. However, suitable plant species still need to be identified for reclamation of substrates presenting a high electrical conductivity. Scope Halophytic plant species are able to cope with several abiotic constraints occurring simultaneously in their natural environment. This review considers their putative interest for remediation of polluted soil in relation to their ability to sequester absorbed toxic ions in trichomes or vacuoles, to perform efficient osmotic adjustment and to limit the deleterious impact of oxidative stress. These physiological adaptations are considered in relation to the impact of salt on heavy metal bioavailabilty in two types of ecosystem: (1) salt marshes and mangroves, and (2) mine tailings in semi-arid areas. Conclusions Numerous halophytes exhibit a high level of heavy metal accumulation and external NaCl may directly influence heavy metal speciation and absorption rate. Maintenance of biomass production and plant water status makes some halophytes promising candidates for further management of heavy-metal-polluted areas in both saline and non-saline environments. PMID:25672360

  15. Low energy ion beam assisted growth of metal multilayers

    Quan, Junjie

    Vapor deposited metal multilayers have attracted a great deal of interest in recent years because they offer extraordinary strength, hardness, heat resistance, and unexpected new properties like high reflectivity and spin-dependent conductivity. The giant magnetoresistance effects discovered in Fe/Cr artificial superstructures in 1988 stimulated a large number of studies on the electronic transport properties of spintronic materials because of their important applications in highly sensitive magnetic sensors, nonvolatile random access memories, and the data storage industry in general. Magnetic multilayers allow exploitation of unique micromagnetic, magnetooptic, and magnetoelectronic phenomena that cannot be realized using conventional materials. For example, if ferromagnetic layers (such as CoFe) with a thicknesses of 5-7 nm are separated by a non-magnetic spacer (such as Cu or AlOx) of an appropriate thickness (1-3 nm), they can exhibit large changes in their electrical resistance when a magnetic field is applied. These changes are caused mainly by spin-dependent conduction electron scattering at magnetic multilayer interfaces. Many experimental and theoretical works have sought to promote a basic understanding of the effect of atomic structure in thin film multilayers upon spin dependent transport. It has been found that interfacial imperfections, such as interfacial roughness and interlayer mixing, dramatically reduce the properties exploited for spintronic applications. A combination of computer modeling and experiments has been used to discover more effective ways to control the interfacial structures of metal multilayers. Earlier atomic simulations had indicated that it is very important to control adatom energy during deposition in order to improve interface properties. Based on these ideas, this dissertation has investigated the effects of low energy ion assistance during metal multilayer deposition. Using molecular dynamics modeling, the effects of ion

  16. A novel dithiourea and its response to metal ions

    Lu Yuan; Hong Zhong; Li Oing Li; Jing Jing Xiao


    The synthesis,characterization,and its response to metal ions of a novel thiourea N,N'-diethoxycarbonyl-N'',N'''-(1,2-ethylidene) dithiourea was reported.The results show that this dithiourea with new structure can react with Cu2+ and Ni2+ separately,and has a best selectivity to Fe3+ ions.Bench-scale flotation tests were also carried out,verifying it has higher copper flotation recovery and better selectivity to sulfide ores containing Cu compared with universal collectors.

  17. Peripheral collisions of highly charged ions with metal clusters

    Zhang Cheng-Jun; Hu Bi-Tao; Luo Xian-Wen


    Within the framework of the dynamical classical over-barrier model,the soft collisions between slow highly charged ions(SHCIs)Ar17+ and the large copper clusters under large impact parameters have been studied in this paper.We present the dominant mechanism of the electron transfer between SHCls and a large metal cluster by computational simulation.The evolution of the occupation of projectile ions,KLχ satellite lines,X-ray yields,Auger electron spectrum and scattering angles are provided.

  18. Solid-liquid solvent extraction of metal ions

    Bo Peng; Haiyan Fan; Jinzhang Gao


    An overview of extraction of some trace metal ions using molten solvent (low melting substance) during last two decadesis presented. The development of this technique since its inception is briefly traced. The comparison of extraction efficiency, thermo-dynamics and kinetics mainly involving extraction of rare earth ions between molten solvent extraction at high temperature and usualliquid-liquid extraction at room temperature are discussed in detail. The various parameters obtained from the previous and presentstudies such as equilibrium extraction constant Kex, pH1/2, thermodynamic and kinetic data are displayed in tabular form. Finally, thecurrent demands, disadvantages and future prospects are also evaluated.

  19. Removal of Heavy Metal Ions From Aqueous Solutions

    maziar noei


    Full Text Available The removal of Zn(II, V(II,  by  silica aerogel has been found to be concentration, , contact time, adsorbent dose and temperature dependent. ion exchange are the major removal mechanisms involved. The adsorption isotherm studies clearly indicated that the adsorptive behaviour of metal ions on silica aerogel  was satisfied. The applicability of the Lagergren kinetic model has also been investigated. Thermodynamic constant (Kad , standard free energy ( ∆G0 ,enthalpy (∆H0 and entropy (∆S0 were calculated for predicting the nature of adsorption

  20. Statistical evaluation of biogeochemical variables affecting spatiotemporal distributions of multiple free metal ion concentrationsin an urban estuary

    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 limite...

  1. MRI probes for sensing biologically relevant metal ions.

    Bonnet, Célia S; Tóth, Eva


    Given the important role of metal ions in fundamental biological processes, the visualization of their concentration in living animals by repeatable, noninvasive imaging techniques, such as MRI, would be highly desirable. A large number of metal-responsive MRI contrast agents, the majority based on Gd(3+) complexes, have been reported in recent years. The contrast-enhancing properties (relaxivity) of a Gd(3+) complex can be most conveniently modulated by interaction with the sensed metal cation via changes in the number of water molecules bound directly to Gd(3+) or changes in the size of the complex, which represent the two major strategies to develop metal sensitive MRI probes. Here, we survey paramagnetic lanthanide complexes involving Gd(3+) agents and paramagnetic chemical exchange saturation transfer probes designed to detect the most important endogenous metal ions: calcium, zinc, iron and copper. Future work will likely focus on extending applications of these agents to living animals, as well as on exploring new ways of creating molecular MRI probes in order to meet requirements such as higher specificity or lower detection limits.

  2. Metal ion toxins and brain aquaporin-4 expression: an overview

    Adriana eXimenes-Da-Silva


    Full Text Available Metal ions such as iron, zinc, and manganese are essential to metabolic functions, protein synthesis, neurotransmission, and antioxidant neuroprotective mechanisms. Conversely, non-essential metals such as mercury and lead are sources of human intoxication due to occupational activities or environmental contamination. Essential or non-essential metal accumulation in the central nervous system (CNS results in changes in blood-brain barrier (BBB permeability, as well as triggering microglia activation and astrocyte reactivity and changing water transport through the cells, which could result in brain swelling. Aquaporin-4 is the main water channel in the CNS, is expressed in astrocyte foot processes in brain capillaries and along the circumventricular epithelium in the ventricles, and has important physiological functions in maintaining brain osmotic homeostasis and supporting brain excitability through regulation of the extracellular space. Some evidence has pointed to a role of AQP4 during metal intoxication in the brain, where it may act in a dual form as a neuroprotector or a mediator of the development of oxidative stress in neurons and astrocytes, resulting in brain swelling and neuronal damage. This mini-review presents the way some metal ions affect changes in AQP4 expression in the CNS and discuss the ways in which water transport in brain cells can be involved in brain damage.

  3. Boron-based refiners: Advantages in semi-solid-metal casting of Al-Si alloys

    Nafisi, Shahrooz [Advanced Materials and Processing Research Group, University of Quebec at Chicoutimi, Quebec G7H 2B1 (Canada)], E-Mail:; Ghomashchi, Reza [Advanced Materials and Processing Research Group, University of Quebec at Chicoutimi, Quebec G7H 2B1 (Canada)


    Inoculation has been studied in the semi-solid-metal (SSM) casting by sole boron addition. By boron addition, the structure is not only refined but also the sphericity of the primary {alpha}-Al particles increased. Higher globularity coupled with smaller primary particles leads to superior flow of the billet in the compression test. It is also shown that the dissolved boron in the matrix of the master alloy and AlB{sub 2} particles are the key parameters in this evolution.0.

  4. Luminescence enhancement of rare earth ions by metal nanostructures



    Well-ordered metal structures,i.e.arrays of nanosized tips on silver surface for studies of the luminescence enhancement of absorbed media with rare earth ions were used.These arrays were prepared by the metal evaporation on track membranes.Calculations of resonance frequencies of tips regarded as semispheroids were done taking into account the interaction between dipoles of tips.They were used to discuss experimental results for media with Eu(NO3)3·6H2O salt basing on data for bulk silver dielectric function.

  5. The Corrosion Protection of Metals by Ion Vapor Deposited Aluminum

    Danford, M. D.


    A study of the corrosion protection of substrate metals by ion vapor deposited aluminum (IVD Al) coats has been carried out. Corrosion protection by both anodized and unanodized IVD Al coats has been investigated. Base metals included in the study were 2219-T87 Al, 7075-T6 Al, Titanium-6 Al-4 Vanadium (Ti-6Al-4V), 4130 steel, D6AC steel, and 4340 steel. Results reveal that the anodized IVD Al coats provide excellent corrosion protection, but good protection is also achieved by IVD Al coats that have not been anodized.

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

    Asakawa, Yoshiki; Yamamoto, Eiichi; Asakawa, Naoki


    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.

  7. Speciation of heavy metal ions as influenced by interactions with montmorillonite, Al hydroxide polymers and citrate.

    Janssen, R.P.T.


    Clay minerals, metal-hydroxides and organic matter can bind metal ions; moreover they also interact with each other. These mutual interactions influence the metal binding to a significant extent. In this study, the speciation of the heavy metal ions Zn and Ph was investigated in model systems consis

  8. Lithium metal doped electrodes for lithium-ion rechargeable chemistry

    Liu, Gao; Battaglia, Vince; Wang, Lei


    An embodiment of the invention combines the superior performance of a polyvinylidene difluoride (PVDF) or polyethyleneoxide (POE) binder, the strong binding force of a styrene-butadiene (SBR) binder, and a source of lithium ions in the form of solid lithium metal powder (SLMP) to form an electrode system that has improved performance as compared to PVDF/SBR binder based electrodes. This invention will provide a new way to achieve improved results at a much reduced cost.

  9. Metal ions: supporting actors in the playbook of small ribozymes.

    Johnson-Buck, Alexander E; McDowell, Sarah E; Walter, Nils G


    Since the 1980s, several small RNA motifs capable of chemical catalysis have been discovered. These small ribozymes, composed of between approximately 40 and 200 nucleotides, have been found to play vital roles in the replication of subviral and viral pathogens, as well as in gene regulation in prokaryotes, and have recently been discovered in noncoding eukaryotic RNAs. All of the known natural small ribozymes - the hairpin, hammerhead, hepatitis delta virus, Varkud satellite, and glmS ribozymes--catalyze the same self-cleavage reaction as RNase A, resulting in two products, one bearing a 2'-3' cyclic phosphate and the other a 5'-hydroxyl group. Although originally thought to be obligate metalloenzymes like the group I and II self-splicing introns, the small ribozymes are now known to support catalysis in a wide variety of cations that appear to be only indirectly involved in catalysis. Nevertheless, under physiologic conditions, metal ions are essential for the proper folding and function of the small ribozymes, the most effective of these being magnesium. Metal ions contribute to catalysis in the small ribozymes primarily by stabilizing the catalytically active conformation, but in some cases also by activating RNA functional groups for catalysis, directly participating in catalytic acid-base chemistry, and perhaps by neutralizing the developing negative charge of the transition state. Although interactions between the small ribozymes and cations are relatively nonspecific, ribozyme activity is quite sensitive to the types and concentrations of metal ions present in solution, suggesting a close evolutionary relationship between cellular metal ion homeostasis and cation requirements of catalytic RNAs, and perhaps RNA in general.

  10. Studies on the Interaction between Catechin and Metal Ions

    Yeom, Jieun; Yang, Ikjun; Park, Okhyun; Park, Hyoungryun [Chonnam National Univ., Gwangju (Korea, Republic of); Bark, Kimin [Gyeongsang National Univ., Chinju (Korea, Republic of); Park, Chulho [Nambu Univ., Gwangju (Korea, Republic of)


    In conclusion, the UV-vis absorption spectra of the deaerated methanolic solution reacted with metal ions such as Cu{sup 2+}, Zn{sup 2+}, Co{sup 2+}, and Fe{sup 3+} were changed as time passed after adding catechin followed by addition of catechin to methanol. This is strongly dependent not only on the presence of metal ion but on the storage time of the solution. The change has relevance to the oxidation of catechin. Oxidation of catechin is first initiated by the dissociation of -OH part of the catechol moiety in methanol and then the ionized anion forms are converted into their oxidized forms called quinones. The higher the standard reduction potential for metal-ion, the faster the oxidation occurs. The steady-state fluorescence emission spectra of catechin changed depending on the storage time of the solution. This finding indicates that oxidation of catechin is undergone by a sequence of multistep reactions in deaerated methanol solution.

  11. Electrospray Ionization Mass Spectrometry: From Cluster Ions to Toxic metal Ions in Biology

    Lentz, Nicholas B. [Iowa State Univ., Ames, IA (United States)


    This dissertation focused on using electrospray ionization mass spectrometry to study cluster ions and toxic metal ions in biology. In Chapter 2, it was shown that primary, secondary and quarternary amines exhibit different clustering characteristics under identical instrument conditions. Carbon chain length also played a role in cluster ion formation. In Chapters 3 and 4, the effects of solvent types/ratios and various instrumental parameters on cluster ion formation were examined. It was found that instrument interface design also plays a critical role in the cluster ion distribution seen in the mass spectrum. In Chapter 5, ESI-MS was used to investigate toxic metal binding to the [Gln11]-amyloid β-protein fragment (1-16). Pb and Cd bound stronger than Zn, even in the presence of excess Zn. Hg bound weaker than Zn. There are endless options for future work on cluster ions. Any molecule that is poorly ionized in positive ion mode can potentially show an increase in ionization efficiency if an appropriate anion is used to produce a net negative charge. It is possible that drug protein or drug/DNA complexes can also be stabilized by adding counter-ions. This would preserve the solution characteristics of the complex in the gas phase. Once in the gas phase, CID could determine the drug binding location on the biomolecule. There are many research projects regarding toxic metals in biology that have yet to be investigated or even discovered. This is an area of research with an almost endless future because of the changing dynamics of biological systems. What is deemed safe today may show toxic effects in the future. Evolutionary changes in protein structures may render them more susceptible to toxic metal binding. As the understanding of toxicity evolves, so does the demand for new toxic metal research. New instrumentation designs and software make it possible to perform research that could not be done in the past. What was undetectable yesterday will

  12. Angular resolved energy analysis of /sup 69/Ga/sup +/ions from a gallium liquid metal ion source

    Marriott, P.


    An analysis system has been designed and built to characterise liquid metal ion source beams. Both mass and angular resolved energy distribution measurements can be made, from which both FWHM energy spreads and energy deficits can be obtained. This paper briefly describes the system and presents and discusses the first off-axis results taken with a gallium liquid metal ion source.

  13. Headgroup interactions and ion flotation efficiency in mixtures of a chelating surfactant, different foaming agents, and divalent metal ions.

    Svanedal, Ida; Boija, Susanne; Norgren, Magnus; Edlund, Håkan


    The correlation between interaction parameters and ion flotation efficiency in mixtures of chelating surfactant metal complexes and different foaming agents was investigated. We have recently shown that chelating surfactant 2-dodecyldiethylenetriaminepentaacetic acid (4-C12-DTPA) forms strong coordination complexes with divalent metal ions, and this can be utilized in ion flotation. Interaction parameters for mixed micelles and mixed monolayer formation for Mg(2+) and Ni(2+) complexes with the chelating surfactant 4-C12-DTPA and different foaming agents were calculated by Rubingh's regular solution theory. Parameters for the calculations were extracted from surface tension measurements and NMR diffusometry. The effects of metal ion coordination on the interactions between 4-C12-DTPA and the foaming agents could be linked to a previously established difference in coordination chemistry between the examined metal ions. As can be expected from mixtures of amphoteric surfactants, the interactions were strongly pH-dependent. Strong correlation was found between interaction parameter β(σ) for mixed monolayer formation and the phase-transfer efficiency of Ni(2+) complexes with 4-C12-DTPA during flotation in a customized flotation cell. In a mixture of Cu(2+) and Zn(2+), the significant difference in conditional stability constants (log K) between the metal complexes was utilized to selectively recover the metal complex with the highest log K (Cu(2+)) by ion flotation. Flotation experiments in an excess concentration of metal ions confirmed the coordination of more than one metal ion to the headgroup of 4-C12-DTPA.

  14. The electron-transfer based interaction between transition metal ions and photoluminescent graphene quantum dots (GQDs): a platform for metal ion sensing.

    Huang, Hongduan; Liao, Lei; Xu, Xiao; Zou, Mingjian; Liu, Feng; Li, Na


    The electron-transfer based quenching effect of commonly encountered transition metal ions on the photoluminescence of grapheme quantum dots (GQDs) was for the first time investigated, and was found to be associated with electron configuration of the individual metal ion. Ethylene diamine tetraacetic acid (EDTA), the metal ion chelator, can competitively interact with metal ions to recover the quenched photoluminescence of GQDs. Basically, metal ions with empty or completely filled d orbits could not quench the photoluminescence of GQDs, but this quenching effect was observed for the metal ions with partly filled d orbits. Based on the quenching-recovering strategy, a simple optical metal sensing platform was established by taking Ni(2+) as an example. Using the nickel ion-specific chelating reagent, dimethylglyoxime (DMG), to replace EDTA, a detection limit of 4.1 μM was obtained in standard solution. This proposed strategy does not need further functionalization of GQDs, facilitating the application for simple, fast and cost-effective screening of metal ions.

  15. The kinetics of bivalent metal ion dissociation from myosin subfragments.

    Bennett, A J; Bagshaw, C R


    Bivalent metal ions have multiple roles in subunit association and ATPase regulation in scallop adductor-muscle myosin. To help elucidate these functions, the rates of Ca2+ and Mg2+ dissociation from the non-specific high-affinity sites on the regulatory light chains were measured and compared with those of rabbit skeletal-muscle myosin subfragments. Ca2+ dissociation had a rate constant of about 0.7 s-1 in both species, as measured by the time course of the pH change on EDTA addition. Mg2+ dissociation had a rate constant of 0.05 s-1, as monitored by its displacement with the paramagnetic Mn2+ ion. It is concluded that the exchange between Ca2+ and Mg2+ at the non-specific site, on excitation of both skeletal and adductor muscles, is too slow to contribute to the activation itself. The release of bivalent metal ions from the non-specific site is, however, the first step in release of the scallop regulatory light chain (Bennett & Bagshaw (1986) Biochem. J. 233, 179-186). In scallop myosin additional specific sites are present, which can bind Ca2+ rapidly, to effect activation of the ATPase. In the course of this work, Ca2+ dissociation from EGTA was studied as a model system. This gave rates of 1 s-1 and 0.3 s-1 at pH 7.0 and pH 8.0 respectively.

  16. DNA strand breakage by bivalent metal ions and ionizing radiation.

    Ayene, Iraimoudi S; Koch, Cameron J; Krisch, Robert E


    To investigate mechanisms of DNA breakage via the interaction of bivalent metal ion, thiol reducing agent and ionizing radiation, in *OH scavenging abilities comparable to those in cells. We measured the effects of 10 min exposure to 200 microM Fe2+ vs. Fe3+ on the induction of single (SSB) and double (DSB) strand breaks in unirradiated and oxically irradiated SV40 DNA, in aqueous solution containing 75 or 750 mM glycerol and/or 5 mM glutathione (GSH). Fe2+ or GSH alone produced little DNA damage. However, their combination produced a dramatic increase in the production of both SSB and DSB. Experiments with ferric ion suggest that it produces DNA damage only after partial reduction to ferrous by GSH. Induction efficiencies for SSB in the presence of Fe2+/GSH showed additivity of the effects of radiation alone with those from Fe2+/GSH. However, the corresponding induction efficiencies for DSB demonstrated a 2.5-fold enhancement. Our results are consistent with a model in which reduced bivalent metal ions plus thiols, in the presence of O2, produce DSB in DNA primarily via local clusters of hydroxyl radicals arising from site specific Fenton reactions. The synergism observed between DSB production by Fe/GSH and by ionizing radiation, also believed to occur via local clusters of hydroxyl radicals, is consistent with this model. Our results suggest that both normally present intracellular iron and ionizing radiation may be important sources of oxidative stress in cells.

  17. Metal ion enhanced binding of AMD3100 to Asp262 in the CXCR4 receptor

    Gerlach, Lars Ole; Jakobsen, Janus S; Jensen, Kasper P;


    +), Zn(2+), or Ni(2+) into the cyclam rings of the compound. The rank order of the transition metal ions correlated with the calculated binding energy between free acetate and the metal ions coordinated in a cyclam ring. Construction of AMD3100 substituted with only a single Cu(2+) or Ni(2+) ion...... demonstrated that the increase in binding affinity of the metal ion substituted bicyclam is achieved through an enhanced interaction of just one of the ring systems. Mutational analysis of potential metal ion binding residues in the main ligand binding crevice of the CXCR4 receptor showed that although binding...... of the bicyclam is dependent on both Asp(171) and Asp(262), the enhancing effect of the metal ion was selectively eliminated by substitution of Asp(262) located at the extracellular end of TM-VI. It is concluded that the increased binding affinity of the metal ion substituted AMD3100 is obtained through enhanced...

  18. Microbial manganese oxide formation and interaction with toxic metal ions.

    Miyata, Naoyuki; Tani, Yukinori; Sakata, Masahiro; Iwahori, Keisuke


    Diverse bacteria and fungi oxidize Mn(II) enzymatically and produce insoluble Mn(III, IV) oxides, and these organisms are considered to be the primal agents for the occurrence of natural Mn oxide phases in most environments. Biogenic Mn oxides have a high sorption capacity for metal cations and an ability to oxidize numerous inorganic and organic compounds, owing to their structural and redox features. Thus, the microbial process is of significance in both biogeochemical and biotechnological contexts. In this article we summarize the enzymatic Mn(II) oxidation and interactions of biogenic Mn oxides with toxic metal and metalloid ions. Although Mn oxide formation by fungi has not been fully characterized yet, recent researches with ascomycetes emphasize the similarity between the bacterial and fungal Mn(II) oxidation with respect to the involved catalyst (i.e., multicopper oxidase-type enzymes) and the reaction product [i.e., layer-type Mn(IV) oxides]. Laboratory cultures of bacterial and fungal Mn oxidizers are expected to provide fundamental knowledge in their potential use for remediation of environments and effluents contaminated with toxic metal(loid) ions.

  19. Effect of transition metal ions on the conductivity and stability of stabilized zirconia

    Lybye, D.; Mogensen, Mogens Bjerg


    the effect of co-doping with smaller transition metal ions such as Ti-, Fe- and Mn-ions. Many of the ionic radii of the transition metal ions are too small compared to the host lattice ionic radius of zirconium. Here we explore the effect of a) the small ionic radii compared to the large ionic radii...

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

    Ibanez, Jorge G.; And Others


    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)

  1. Hydration number of alkali metal ions determined by insertion in a conducting polymer

    Skaarup, Steen


    . The solvation of alkali metal ions has been discussed for many years without a clear consensus. This work presents a systematic study of the hydration numbers of the 5 alkali metal ions, using the electrochemical insertion of the ions in a conducting polymer (polypyrrole containing the large immobile anion DBS...

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

    Ibanez, Jorge G.; And Others


    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)

  3. Lanthanide metal-organic frameworks as selective microporous materials for adsorption of heavy metal ions.

    Jamali, Abbas; Tehrani, Alireza Azhdari; Shemirani, Farzaneh; Morsali, Ali


    Four microporous lanthanide metal-organic frameworks (MOFs), namely Ln(BTC)(H2O)(DMF)1.1 (Ln = Tb, Dy, Er and Yb, DMF = dimethylformamide, H3BTC = benzene-1,3,5-tricarboxylic acid), have been used for selective adsorption of Pb(ii) and Cu(ii). Among these MOFs, the Dy-based MOF shows better adsorption property and selectivity toward Pb(ii) and Cu(ii) ions. Adsorption isotherms indicate that sorption of Pb(ii) and Cu(ii) on MOFs is via monolayer coverage. Preconcentration is based on solid-phase extraction in which MOFs were rapidly injected into water samples and adsorption of metal ions was rapid because of good contact with analyte; then adsorbed Pb(ii) and Cu(ii) ions were analyzed by FAAS. The optimized methodology represents good linearity between 1 and 120 μg L(-1) and detection limit of 0.4 and 0.26 μg L(-1) for Pb(ii) and Cu(ii), respectively. Subsequently the method was evaluated for preconcentration of target metal ions in some environmental water samples.

  4. Using Nondestructive Portable X-ray Fluorescence Spectrometers on Stone, Ceramics, Metals, and Other Materials in Museums: Advantages and Limitations.

    Tykot, Robert H


    Elemental analysis is a fundamental method of analysis on archaeological materials to address their overall composition or identify the source of their geological components, yet having access to instrumentation, its often destructive nature, and the time and cost of analyses have limited the number and/or size of archaeological artifacts tested. The development of portable X-ray fluorescence (pXRF) instruments over the past decade, however, has allowed nondestructive analyses to be conducted in museums around the world, on virtually any size artifact, producing data for up to several hundred samples per day. Major issues have been raised, however, about the sensitivity, precision, and accuracy of these devices, and the limitation of performing surface analysis on potentially heterogeneous objects. The advantages and limitations of pXRF are discussed here regarding archaeological studies of obsidian, ceramics, metals, bone, and painted materials.

  5. Controlled charge exchange between alkaline earth metals and their ions

    Gacesa, Marko; Côté, Robin


    We theoretically investigate the prospects of realizing controlled charge exchange via magnetic Feshbach resonances in cold and ultracold collisions of atoms and ions. In particular, we focus on near-resonant charge exchange in heteroisotopic combinations of alkaline earth metals, such as 9Be++10 Be9 Be+10Be+ , which exhibit favorable electronic and hyperfine structure. The quantum scattering calculations are performed for a range of initial states and experimentally attainable magnetic fields in standard coupled-channel Feshbach projection formalism, where higher-order corrections such as the mass-polarization term are explicitely included. In addition, we predict a number of magnetic Feshbach resonances for different heteronuclear isotopic combinations of the listed and related alkaline earth elements. Our results imply that near-resonant charge-exchange could be used to realize atom-ion quantum gates, as well as controlled charge transfer in optically trapped cold quantum gases. This work is partially supported by ARO.

  6. Alloying of metal nanoparticles by ion-beam induced sputtering

    Magudapathy, P.; Srivastava, S. K.; Gangopadhyay, P.; Amirthapandian, S.; Saravanan, K.; Das, A.; Panigrahi, B. K.


    Ion-beam sputtering technique has been utilized for controlled synthesis of metal alloy nanoparticles of compositions that can be tuned. Analysis of various experimental results reveals the formation of Ag-Cu alloy nanoparticles on a silica substrate. Surface-plasmon optical resonance positions and observed shifts of Ag Bragg angles in X-ray diffraction pattern particularly confirm formation of alloy nanoparticles on glass samples. Sputtering induced nano-alloying mechanism has been discussed and compared with thermal mixing of Ag and Cu thin films on glass substrates. Compositions and sizes of alloy nanoparticles formed during ion-beam induced sputtering are found to exceed far from the values of thermal mixing.

  7. Metal-organic frameworks for lithium ion batteries and supercapacitors

    Ke, Fu-Sheng; Wu, Yu-Shan; Deng, Hexiang


    Porous materials have been widely used in batteries and supercapacitors attribute to their large internal surface area (usually 100-1000 m2 g-1) and porosity that can favor the electrochemical reaction, interfacial charge transport, and provide short diffusion paths for ions. As a new type of porous crystalline materials, metal-organic frameworks (MOFs) have received huge attention in the past decade due to their unique properties, i.e. huge surface area (up to 7000 m2 g-1), high porosity, low density, controllable structure and tunable pore size. A wide range of applications including gas separation, storage, catalysis, and drug delivery benefit from the recent fast development of MOFs. However, their potential in electrochemical energy storage has not been fully revealed. Herein, the present mini review appraises recent and significant development of MOFs and MOF-derived materials for rechargeable lithium ion batteries and supercapacitors, to give a glimpse into these potential applications of MOFs.

  8. Metal-organic frameworks for lithium ion batteries and supercapacitors

    Ke, Fu-Sheng; Wu, Yu-Shan; Deng, Hexiang, E-mail:


    Porous materials have been widely used in batteries and supercapacitors attribute to their large internal surface area (usually 100–1000 m{sup 2} g{sup −1}) and porosity that can favor the electrochemical reaction, interfacial charge transport, and provide short diffusion paths for ions. As a new type of porous crystalline materials, metal-organic frameworks (MOFs) have received huge attention in the past decade due to their unique properties, i.e. huge surface area (up to 7000 m{sup 2} g{sup −1}), high porosity, low density, controllable structure and tunable pore size. A wide range of applications including gas separation, storage, catalysis, and drug delivery benefit from the recent fast development of MOFs. However, their potential in electrochemical energy storage has not been fully revealed. Herein, the present mini review appraises recent and significant development of MOFs and MOF-derived materials for rechargeable lithium ion batteries and supercapacitors, to give a glimpse into these potential applications of MOFs. - Graphical abstract: MOFs with large surface area and high porosity can offer more reaction sites and charge carriers diffusion path. Thus MOFs are used as cathode, anode, electrolyte, matrix and precursor materials for lithium ion battery, and also as electrode and precursor materials for supercapacitors. - Highlights: • MOFs have potential in electrochemical area due to their high porosity and diversity. • We summarized and compared works on MOFs for lithium ion battery and supercapacitor. • We pointed out critical challenges and provided possible solutions for future study.

  9. Clusters distributions on charges and dimensions at ion metal sputtering

    Matveev, V I


    The theory on the metal sputtering in form of large (with the atoms number N >= 5) neutral and charged clusters under the impact of the ion bombardment is considered. The probability of the cluster emission, consisting of the N atoms, is calculated on the basis of the Einstein model. The charge state of the cluster, consisting of the N atoms, is determined. The obtained formulae agree well with the experimental results. It is noted, that the mass-spectra of the neutral clusters slightly depend on the target temperature, whereas the mass-spectra of the single charge clusters essentially depend on the target temperature

  10. Metal ion interaction of an oligopeptide fragment representing the regulatory metal binding site of a CueR protein

    Jancsó, Attila; Szokolai, Hajnalka; Roszahegyi, Livia;


    Metalloregulatory proteins of the MerR family are transcriptional activators that sense/control the concentration of various metal ions inside bacteria.1 The Cu+ efflux regulator CueR, similarly to other MerR proteins, possesses a short multiple Cys-containing metal binding loop close to the C......-terminus. CueR has a high selectivity for Cu+, Ag+ and Au+, but exhibits no transcriptional activity for the divalent ions Hg2+ and Zn2+.2 The two Cys- residues of the metal binding loop were shown to settle M+ ions into a linear coordination environment but other factors may also play a role in the recognition...... of cognate metal ions.2 Nevertheless, it is an interesting question whether the same sequence, when removed from the protein, shows a flexibility to adopt different coordination environments and may efficiently bind metal ions having preferences for larger coordination numbers....

  11. Novel forward osmosis process to effectively remove heavy metal ions

    Cui, Yue


    In this study, a novel forward osmosis (FO) process for the removal of heavy metal ions from wastewater was demonstrated for the first time. The proposed FO process consists of a thin-film composite (TFC) FO membrane made from interfacial polymerization on a macrovoid-free polyimide support and a novel bulky hydroacid complex Na4[Co(C6H4O7)2]·r2H2O (Na-Co-CA) as the draw solute to minimize the reverse solute flux. The removal of six heavy metal solutions, i.e., Na2Cr2O7, Na2HAsO4, Pb(NO3)2, CdCl2, CuSO4, Hg(NO3)2, were successfully demonstrated. Water fluxes around 11L/m2/h (LMH) were harvested with heavy metals rejections of more than 99.5% when employing 1M Na-Co-CA as the draw solution to process 2000ppm(1 ppm=1 mg/L) heavy metal solutions at room temperature. This FO performance outperforms most nanofiltration (NF) processes. In addition, the high rejections were maintained at 99.5% when a more concentrated draw solution (1.5M) or feed solution (5000ppm) was utilized. Furthermore, rejections greater than 99.7% were still achieved with an enhanced water flux of 16.5LMH by operating the FO process at 60°C. The impressive heavy metal rejections and satisfactory water flux under various conditions suggest great potential of the newly developed FO system for the treatment of heavy metal wastewater. © 2014 Elsevier B.V.

  12. Acetabular bone density and metal ions after metal-on-metal versus metal-on-polyethylene total hip arthroplasty; short-term results

    Zijlstra, Wierd P.; van der Veen, Hugo C.; van den Akker-Scheek, Inge; Zee, Mark J. M.; Bulstra, Sjoerd K.; van Raay, Jos J. A. M.


    Information on periprosthetic acetabular bone density is lacking for metal-on-metal total hip arthroplasties. These bearings use cobalt-chromium instead of titanium acetabular components, which could lead to stress shielding and hence periprosthetic bone loss. Cobalt and chromium ions have detriment

  13. Effect of metal ions on some pharmacologically relevant interactions involving fluoroquinolone antibiotics.

    Seedher, Neelam; Agarwal, Pooja


    Complexation of five metal cations, Fe(3+), Al(3+), Zn(2+), Cu(2+) and Mg(2+) with four fluoroquinolones, levofloxacin, sparfloxacin, ciprofloxacin hydrochloride and enrofloxacin and human serum albumin (HSA) has been studied for better understanding of bioavailability of drugs interacting with metals and proteins. The binding parameters have been determined using fluorescence and ultraviolet absorption spectroscopic techniques. The effect of metal cations on the interaction of fluoroquinolones with HSA has also been investigated. The association constants were of the order of 10(2)-10(4) for the fluoroquinolone-metal ion interaction. For a given drug, the chelation potential of Al(3+) was highest, whereas that of Mg(2+) was lowest. At a metal ion/drug ratio of 1:1, approximately 50%-73% of metal ion was bound per mole drug in most cases. In the case of HSA-metal ion interaction, for Fe(3+) and Zn(2+) ions, there was only one class of binding site, whereas for Al(3+) and Cu(2+) ions, two types of binding sites were found. The relative affinity of various metal ions was found to vary as Al(3+)>Cu(2+)>Zn(2+)>Fe(3+). The extent of binding was found to be independent of the charge on the ion. Owing to very weak quenching of fluorescence, the association constant for the interaction of Mg(2+) ion could not be determined by this technique. The binding affinity of all the fluoroquinolones to HSA was found to increase in the presence of Cu(2+) ions, whereas all other metal ions decreased the binding -affinity with the exception of levofloxacin in the presence of Zn(2+) and Al(3+) ions. Increase in the binding affinity indicated that the metal ions facilitate HSA-fluoroquinolone interaction and fluoroquinolones probably interact with HSA via a metal ion bridge. Decrease in the binding affinity, by contrast, can either be due to the fact that fluoroquinolone-metal ion complex inhibits fluoroquinolone-HSA interaction or metal ions produce conformational changes in the HSA

  14. Amperometric detection of heavy metal ions in ion pair chromatography at an array of water/nitrobenzene micro interfaces

    Wilke, S. [Martin-Luther-Univ. Halle-Wittenberg, Merseburg (Germany). Fachbereich Chemie; Wang, H. [Martin-Luther-Univ. Halle-Wittenberg, Merseburg (Germany). Fachbereich Chemie; Muraczewska, M. [Martin-Luther-Univ. Halle-Wittenberg, Merseburg (Germany). Fachbereich Chemie; Mueller, H. [Martin-Luther-Univ. Halle-Wittenberg, Merseburg (Germany). Fachbereich Chemie


    A novel amperometric detector for heavy metal ions has been developed and successfully applied for ion pair chromatography. The detector is based on the electrochemical transfer of the metal ions across an array of water/nitrobenzene micro interfaces. The ion transfer is facilitated by the neutral ionophores methylenebis(diphenylphosphineoxide) and methylenebis(di- phenylphosphinesulfide). More than eight metals are separated in less than 15 min on an RP18 column using octyl sulfonate as ion pair reagent. For the heavy metals, the limits of decision are 19(Pb{sup 2+}), 9(Zn{sup 2+}), 9l (Co{sup 2+}), 8(Cd{sup 2+}) and 1.6(Mn{sup 2+}) {mu}g/L. The applicability of the new method for water samples is demonstrated. (orig.). With 3 figs., 2 tabs.

  15. Most spin-1/2 transition-metal ions do have single ion anisotropy

    Liu, Jia; Whangbo, Myung-Hwan, E-mail:, E-mail: [Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695 (United States); Koo, Hyun-Joo [Department of Chemistry and Research Institute for Basic Sciences, Kyung Hee University, Seoul 130-701 (Korea, Republic of); Xiang, Hongjun, E-mail:, E-mail: [Key Laboratory of Computational Physical Sciences (Ministry of Education), State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433 (China); Kremer, Reinhard K. [Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart (Germany)


    The cause for the preferred spin orientation in magnetic systems containing spin-1/2 transition-metal ions was explored by studying the origin of the easy-plane anisotropy of the spin-1/2 Cu{sup 2+} ions in CuCl{sub 2}·2H{sub 2}O, LiCuVO{sub 4}, CuCl{sub 2}, and CuBr{sub 2} on the basis of density functional theory and magnetic dipole-dipole energy calculations as well as a perturbation theory treatment of the spin-orbit coupling. We find that the spin orientation observed for these spin-1/2 ions is not caused by their anisotropic spin exchange interactions, nor by their magnetic dipole-dipole interactions, but by the spin-orbit coupling associated with their crystal-field split d-states. Our study also predicts in-plane anisotropy for the Cu{sup 2+} ions of Bi{sub 2}CuO{sub 4} and Li{sub 2}CuO{sub 2}. The results of our investigations dispel the mistaken belief that magnetic systems with spin-1/2 ions have no magnetic anisotropy induced by spin-orbit coupling.

  16. Metal ion binding with dehydroannulenes - Plausible two-dimensional molecular sieves

    B Sateesh; Y Soujanya; G Narahari Sastry


    Theoretical investigations have been carried out at B3LYP/6-311++G∗∗ level of theory to study the binding interaction of various metal ions, Li+, Na+ and K+ with dehydroannulene systems. The present study reveals that alkali metal ions bind strongly to dehydroannulenes and the passage through the central cavity is controlled by the size of metal ion and dimension of dehydroannulene cavity.

  17. Triboelectrification-Enabled Self-Powered Detection and Removal of Heavy Metal Ions in Wastewater.

    Li, Zhaoling; Chen, Jun; Guo, Hengyu; Fan, Xing; Wen, Zhen; Yeh, Min-Hsin; Yu, Chongwen; Cao, Xia; Wang, Zhong Lin


    A fundamentally new working principle into the field of self-powered heavy-metal-ion detection and removal using the triboelectrification effect is introduced. The as-developed tribo-nanosensors can selectively detect common heavy metal ions. The water-driven triboelectric nanogenerator is taken as a sustainable power source for heavy-metal-ion removal by recycling the kinetic energy from flowing wastewater.

  18. Liquid-liquid extraction of metal ions by the 6-membered N-containing macrocycle hexacyclen.

    Arpadjan, S; Mitewa, M; Bontchev, P R


    The nitrogen-containing analogue of 18-crown-6, 1,4,7,10,13,16-hexa-azaoctadecane (hexacyclen)] was studied as a reagent for complexation and extraction of some metal ions. It was found that with this reagent and methyl isobutyl ketone, metal ions such as silver(I), mercury(II), copper(II), platinum(II) and palladium(II) can be quantitatively extracted and separated from iron(III) and some other metal ions.

  19. Electrospray droplet exposure to organic vapors: metal ion removal from proteins and protein complexes.

    DeMuth, J Corinne; McLuckey, Scott A


    The exposure of aqueous nanoelectrospray droplets to various organic vapors can dramatically reduce sodium adduction on protein ions in positive ion mass spectra. Volatile alcohols, such as methanol, ethanol, and isopropanol lead to a significant reduction in sodium ion adduction but are not as effective as acetonitrile, acetone, and ethyl acetate. Organic vapor exposure in the negative ion mode, on the other hand, has essentially no effect on alkali ion adduction. Evidence is presented to suggest that the mechanism by which organic vapor exposure reduces alkali ion adduction in the positive mode involves the depletion of alkali metal ions via ion evaporation of metal ions solvated with organic molecules. The early generation of metal/organic cluster ions during the droplet desolvation process results in fewer metal ions available to condense on the protein ions formed via the charged residue mechanism. These effects are demonstrated with holomyoglobin ions to illustrate that the metal ion reduction takes place without detectable protein denaturation, which might be revealed by heme loss or an increase in charge state distribution. No evidence is observed for denaturation with exposure to any of the organic vapors evaluated in this work.

  20. Metal ion sorption by untreated and chemically treated biomass

    Kilbane, J.J.; Xie, J.


    The metal-binding ability of biosorbents is well known; however, in comparison with commercial ion-exchange resins the capacity of biosorbents is low. The purpose of this research was to examine chemically modified biosorbents and biosorbents prepared from microorganisms isolated from extreme environments to determine if significant improvements in metal-binding capacity or biosorbents with unique capabilities could be produced. Chemical treatments examined included acid, alkali, carbon disulfide, phosphorus oxychloride, anhydrous formamide, sodium thiosulfate, sodium chloroacetic acid, and phenylsulfonate. Biosorbents were prepared from microorganisms isolated from pristine and acid mine drainage impacted sites and included heterotrophs, methanotrophs, algae, and sulfate reducers. Chemical modification with carbon disulfide, phosphorous oxychloride, and sodium thiosulfate yielded biosorbents with such as much as 74%, 133%, and 155% improvements, respectively, in metal-binding capacity, but the performance of these chemically modified biosorbents deteriorated upon repeated use. A culture isolated from an acid mine drainage impacted site, IGTM17, exhibits about 3-fold higher metal-binding capacity in comparison with other biosorbents examined in this study. IGTM17 also exhibits superior metal-binding ability at decreased pH or in the presence of interfering common cations in comparison with other biosorbents or some commercially available cation exchange resins. Some biosorbents, such as IGTM5, can bind anions. To our knowledge this is the first demonstration of the ability of biosorbents to bind anions. Moreover, preliminary data indicate that the chemical modification of biosorbents may be capable of imparting the ability to selectively bind certain anions. Further research is needed to optimize conditions for the chemical modification and stabilization of biosorbents.

  1. Polaronic Transport in Phosphate Glasses Containing Transition Metal Ions

    Henderson, Mark

    The goal of this dissertation is to characterize the basic transport properties of phosphate glasses containing various amounts of TIs and to identify and explain any electronic phase transitions which may occur. The P2 O5-V2O5-WO3 (PVW) glass system will be analyzed to find the effect of TI concentration on conduction. In addition, the effect of the relative concentrations of network forming ions (SiO2 and P2O5) on transport will be studied in the P2O5-SiO2-Fe2O 3 (PSF) system. Also presented is a numerical study on a tight-binding model adapted for the purposes of modelling Gaussian traps, mimicking TI's, which are arranged in an extended network. The results of this project will contribute to the development of fundamental theories on the electronic transport in glasses containing mixtures of transition oxides as well as those containing multiple network formers without discernible phase separation. The present study on the PVW follows up on previous investigation into the effect on mixed transition ions in oxide glasses. Past research has focused on glasses containing transition metal ions from the 3d row. The inclusion of tungsten, a 5d transition metal, adds a layer of complexity through the mismatch of the energies of the orbitals contributing to localized states. The data have indicated that a transition reminiscent of a metal-insulator transition (MIT) occurs in this system as the concentration of tungsten increases. As opposed to some other MIT-like transitions found in phosphate glass systems, there seems to be no polaron to bipolaron conversion. Instead, the individual localization parameter for tungsten noticeably decreases dramatically at the transition point as well as the adiabaticity. Another distinctive feature of this project is the study of the PSF system, which contains two true network formers, phosphorous pentoxide (P2O 5) and silicon dioxide (SiO2). It is not usually possible to do a reliable investigation of the conduction properties of

  2. Properties of Hydrated Alkali Metals Aimed at the Ion Channel Selectivity

    AN Hai-Long; LIU Yu-Zhi; ZHANG Su-Hua; ZHAN Yong; ZHANG Hai-Lin


    The hydration structure properties of different alkali metal ions with eight water molecules and potassium ions with different numbers of water molecules are studied using the mixed density functional theory, B3LYP, with 6-311G basis set. The hydration structures are obtained from structure optimization and the optimum numbers of water molecules in the innermost hydration shell for the alkali metal ions are found. Some useful information about the ion channel selectivity is presented.

  3. Nanoparticles reduce nickel allergy by capturing metal ions

    Vemula, Praveen Kumar; Anderson, R. Rox; Karp, Jeffrey M.


    Approximately 10% of the population in the USA suffer from nickel allergy, and many are unable to wear jewellery or handle coins and other objects that contain nickel. Many agents have been developed to reduce the penetration of nickel through skin, but few formulations are safe and effective. Here, we show that applying a thin layer of glycerine emollient containing nanoparticles of either calcium carbonate or calcium phosphate on an isolated piece of pig skin (in vitro) and on the skin of mice (in vivo) prevents the penetration of nickel ions into the skin. The nanoparticles capture nickel ions by cation exchange, and remain on the surface of the skin, allowing them to be removed by simple washing with water. Approximately 11-fold fewer nanoparticles by mass are required to achieve the same efficacy as the chelating agent ethylenediamine tetraacetic acid. Using nanoparticles with diameters smaller than 500 nm in topical creams may be an effective way to limit the exposure to metal ions that can cause skin irritation.

  4. New Proton-Ionizable, Calixarene-Based Ligands for Selective Metal Ion Separations

    Bartsch, Richard A.


    The project objective was the discovery of new ligands for performing metal ion separations. The research effort entailed the preparation of new metal ion complexing agents and polymers and their evaluation in metal ion separation processes of solvent extraction, synthetic liquid membrane transport, and sorption. Structural variations in acyclic, cyclic, and bicyclic organic ligands were used to probe their influence upon the efficiency and selectivity with which metal ion separations can be performed. A unifying feature of the ligand structures is the presence of one (or more) side arm with a pendent acidic function. When a metal ion is complexed within the central cavity of the ligand, ionization of the side arm(s) produces the requisite anion(s) for formation of an overall electroneutral complex. This markedly enhances extraction/transport efficiency for separations in which movement of aqueous phase anions of chloride, nitrate, or sulfate into an organic medium would be required. Through systematic structural variations, new ligands have been developed for efficient and selective separations of monovalent metal ions (e.g., alkali metal, silver, and thallium cations) and of divalent metal ion species (e.g., alkaline earth metal, lead, and mercury cations). Research results obtained in these fundamental investigations provide important insight for the design and development of ligands suitable for practical metal ion separation applications.

  5. Prostate cancer outcome and tissue levels of metal ions

    Sarafanov, A.G.; Todorov, T.I.; Centeno, J.A.; MacIas, V.; Gao, W.; Liang, W.-M.; Beam, C.; Gray, Michael A.; Kajdacsy-Balla, A.


    BACKGROUND There are several studies examining prostate cancer and exposure to cadmium, iron, selenium, and zinc. Less data are available on the possible influence of these metal ions on prostate cancer outcome. This study measured levels of these ions in prostatectomy samples in order to examine possible associations between metal concentrations and disease outcome. METHODS We obtained formalin fixed paraffin embedded tissue blocks of prostatectomy samples of 40 patients with PSA recurrence, matched 1:1 (for year of surgery, race, age, Gleason grading, and pathology TNM classification) with tissue blocks from 40 patients without recurrence (n = 80). Case-control pairs were compared for the levels of metals in areas adjacent to tumors. Inductively coupled plasma-mass spectrometry (ICP-MS) was used for quantification of Cd, Fe, Zn, and Se. RESULTS Patients with biochemical (PSA) recurrence of disease had 12% lower median iron (95 ??g/g vs. 111 ??g/g; P = 0.04) and 21% lower zinc (279 ??g/g vs. 346 ??g/g; P = 0.04) concentrations in the normal-appearing tissue immediately adjacent to cancer areas. Differences in cadmium (0.489 ??g/g vs. 0.439 ??g/g; 4% higher) and selenium (1.68 ??g/g vs. 1.58 ??g/g; 5% higher) levels were not statistically significant in recurrence cases, when compared to non-recurrences (P = 0.40 and 0.21, respectively). CONCLUSIONS There is an association between low zinc and low iron prostate tissue levels and biochemical recurrence in prostate cancer. Whether these novel findings are a cause or effect of more aggressive tumors, or whether low zinc and iron prostatic levels raise implications for therapy, remains to be investigated. Copyright ?? 2011 Wiley-Liss, Inc.

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

    Devi, Jai; Batra, Nisha; Malhotra, Rajesh


    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 Mnantibacterial 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.

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

    Devi, Jai; Batra, Nisha; Malhotra, Rajesh


    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 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.

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

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


    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.

  9. Metal is not inert: role of metal ions released by biocorrosion in aseptic loosening--current concepts.

    Cadosch, Dieter; Chan, Erwin; Gautschi, Oliver P; Filgueira, Luis


    Metal implants are essential therapeutic tools for the treatment of bone fractures and joint replacements. The metals and metal alloys used in contemporary orthopedic and trauma surgery are well tolerated by the majority of patients. However, complications resulting from inflammatory and immune reactions to metal implants have been well documented. This review briefly discusses the different mechanisms of metal implant corrosion in the human body, which lead to the release of significant levels of metal ions into the peri-implant tissues and the systemic blood circulation. Additionally, this article reviews the effects of the released ions on bone metabolism and the immune system and discusses their involvement in the pathophysiological mechanisms of aseptic loosening and metal hypersensitivity in patients with metal implants.

  10. Transition Metal Ions at the Crossroads of Mucosal Immunity and Microbial Pathogenesis

    Vladimir eDiaz-Ochoa


    Full Text Available Transition metal ions are essential micronutrients for all living organisms. In mammals, these ions are often protein-bound and sequestered within cells, limiting their availability to microbes. Moreover, in response to infection, mammalian hosts further reduce the availability of metal nutrients by activating epithelial cells and recruiting neutrophils, both of which release metal-binding proteins with antimicrobial function. Microorganisms, in turn, have evolved sophisticated systems to overcome these limitations and acquire the metal ions essential for their growth. Here we review some of the mechanisms employed by the host and by pathogenic microorganisms to compete for transition metal ions, with a discussion of how evading nutritional immunity benefits pathogens. Furthermore, we provide new insights on the mechanisms of host-microbe competition for metal ions in the mucosa, particularly in the inflamed gut.

  11. Rational design of metal ion sequestering agents. 1998 annual progress report

    Raymond, K.N.


    'This project addresses fundamental issues and requirements in developing hazardous metal ion separation technologies needed in the treatment and disposal of radioactive and chemical toxic waste. It encompasses the synthesis of new agents, followed by their characterization and evaluation, with the aim to optimize their metal ion sequestering properties for use in applied technologies. This research is focused on the following key areas: (1) basic design and synthesis of new metal ion specific sequestering ligands; (2) structural and thermodynamic investigations of these ligands and their complexes formed with the targeted metal ions; and (3) development of sequestering agents and their incorporation into systems designed to be prototypes of inexpensive and highly effective materials for hazardous metal ion decontamination. Basic studies of the sequestration of relevant toxic metals are required in order to develop processes that will treat effluents sufficiently well to allow direct release into the environment and minimize the production of secondary wastes.'

  12. Metal ion interaction of an oligopeptide fragment representing the regulatory metal binding site of a CueR protein

    Jancsó, Attila; Szokolai, Hajnalka; Roszahegyi, Livia


    Metalloregulatory proteins of the MerR family are transcriptional activators that sense/control the concentration of various metal ions inside bacteria.1 The Cu+ efflux regulator CueR, similarly to other MerR proteins, possesses a short multiple Cys-containing metal binding loop close to the C......-terminus. CueR has a high selectivity for Cu+, Ag+ and Au+, but exhibits no transcriptional activity for the divalent ions Hg2+ and Zn2+.2 The two Cys- residues of the metal binding loop were shown to settle M+ ions into a linear coordination environment but other factors may also play a role in the recognition...

  13. Metal ions, not metal-catalyzed oxidative stress, cause clay leachate antibacterial activity.

    Caitlin C Otto

    Full Text Available Aqueous leachates prepared from natural antibacterial clays, arbitrarily designated CB-L, release metal ions into suspension, have a low pH (3.4-5, generate reactive oxygen species (ROS and H2O2, and have a high oxidation-reduction potential. To isolate the role of pH in the antibacterial activity of CB clay mixtures, we exposed three different strains of Escherichia coli O157:H7 to 10% clay suspensions. The clay suspension completely killed acid-sensitive and acid-tolerant E. coli O157:H7 strains, whereas incubation in a low-pH buffer resulted in a minimal decrease in viability, demonstrating that low pH alone does not mediate antibacterial activity. The prevailing hypothesis is that metal ions participate in redox cycling and produce ROS, leading to oxidative damage to macromolecules and resulting in cellular death. However, E. coli cells showed no increase in DNA or protein oxidative lesions and a slight increase in lipid peroxidation following exposure to the antibacterial leachate. Further, supplementation with numerous ROS scavengers eliminated lipid peroxidation, but did not rescue the cells from CB-L-mediated killing. In contrast, supplementing CB-L with EDTA, a broad-spectrum metal chelator, reduced killing. Finally, CB-L was equally lethal to cells in an anoxic environment as compared to the aerobic environment. Thus, ROS were not required for lethal activity and did not contribute to toxicity of CB-L. We conclude that clay-mediated killing was not due to oxidative damage, but rather, was due to toxicity associated directly with released metal ions.

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

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


    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.

  15. Process for the displacement of cyanide ions from metal-cyanide complexes

    Smith, Barbara F.; Robinson, Thomas W.


    The present invention relates to water-soluble polymers and the use of such water-soluble polymers in a process for the displacement of the cyanide ions from the metal ions within metal-cyanide complexes. The process waste streams can include metal-cyanide containing electroplating waste streams, mining leach waste streams, mineral processing waste streams, and related metal-cyanide containing waste streams. The metal ions of interest are metals that give very strong complexes with cyanide, mostly iron, nickel, and copper. The physical separation of the water-soluble polymer-metal complex from the cyanide ions can be accomplished through the use of ultrafiltration. Once the metal-cyanide complex is disrupted, the freed cyanide ions can be recovered for reuse or destroyed using available oxidative processes rendering the cyanide nonhazardous. The metal ions are released from the polymer, using dilute acid, metal ion oxidation state adjustment, or competing chelating agents, and collected and recovered or disposed of by appropriate waste management techniques. The water-soluble polymer can then be recycled. Preferred water-soluble polymers include polyethyleneimine and polyethyleneimine having a catechol or hydroxamate group.

  16. The Relationship of Culture Media Composition and Chemical Composition on Spirulina sp for Metal Ion Adsorbent

    Hilda Zulkifli


    Full Text Available The analysis relationship of Spirulina sp medium with chemical composition has been conducted. Chemical analysis was performed using X-Ray Fluorescence analysis. Furthermore, potention of Spirulina sp as adsorbent of metal ions was analyzed using FTIR spectroscopy. The results showed that metals such as Zn, Fe, Mn, Ca, Cu, and Mo were mainly metals in Spirulina sp. These metals were not correlated with cultivated medium of Spirulina sp. Analysis of potention Spirulina sp as metal ions adsorbent showed that Spirulina sp has functional groups –C=O and –OH as ligand. Intercation of metal ions Cu(II and Cr(III with Spirulina sp indicated that metal ions bond to –C=O functional group.

  17. Heterogeneous behavior of metalloproteins toward metal ion binding and selectivity: insights from molecular dynamics studies.

    Gogoi, Prerana; Chandravanshi, Monika; Mandal, Suraj Kumar; Srivastava, Ambuj; Kanaujia, Shankar Prasad


    About one-third of the existing proteins require metal ions as cofactors for their catalytic activities and structural complexities. While many of them bind only to a specific metal, others bind to multiple (different) metal ions. However, the exact mechanism of their metal preference has not been deduced to clarity. In this study, we used molecular dynamics (MD) simulations to investigate whether a cognate metal (bound to the structure) can be replaced with other similar metal ions. We have chosen seven different proteins (phospholipase A2, sucrose phosphatase, pyrazinamidase, cysteine dioxygenase (CDO), plastocyanin, monoclonal anti-CD4 antibody Q425, and synaptotagmin 1 C2B domain) bound to seven different divalent metal ions (Ca(2+), Mg(2+), Zn(2+), Fe(2+), Cu(2+), Ba(2+), and Sr(2+), respectively). In total, 49 MD simulations each of 50 ns were performed and each trajectory was analyzed independently. Results demonstrate that in some cases, cognate metal ions can be exchanged with similar metal ions. On the contrary, some proteins show binding affinity specifically to their cognate metal ions. Surprisingly, two proteins CDO and plastocyanin which are known to bind Fe(2+) and Cu(2+), respectively, do not exhibit binding affinity to any metal ion. Furthermore, the study reveals that in some cases, the active site topology remains rigid even without cognate metals, whereas, some require them for their active site stability. Thus, it will be interesting to experimentally verify the accuracy of these observations obtained computationally. Moreover, the study can help in designing novel active sites for proteins to sequester metal ions particularly of toxic nature.

  18. Competitive adsorption of heavy metal ions on peat

    LIU Zhi-rong; ZHOU Li-min; WEI Peng; ZENG Kai; WEN Chuan-xi; LAN Hui-hua


    The uptake capacities, and the adsorption kinetics, of copper, Cu(Ⅱ), nickel, Ni(Ⅱ), and cadmium, Cd(Ⅱ), on peat have been studied under static conditions. The results show that the adsorption rates are rapid: equilibrium is reached in twenty minutes. The adsorption of copper, nickel and cadmium is pH dependent over the pH range from 2 to 6. The adsorption kinetics can be excellently described by the Elovich kinetic equation. The adsorption isotherm fits a Langmuir model very well. The adsorption capacifies follow the order Cu2+>Ni2+>Cd2+ in single-component systems and the competitive adsorption capacities fall in the decreasing order Cu2+> Ni2+>Cd2+ in multi-component systems. The adsorption capacities of these three heavy metal ions on peat are consistent with their observed competitive adsorption capacities.

  19. Surface modification by metal ion implantation forming metallic nanoparticles in an insulating matrix

    Salvadori, M. C.; Teixeira, F. S.; Sgubin, L. G.; Cattani, M.; Brown, I. G.


    There is special interest in the incorporation of metallic nanoparticles in a surrounding dielectric matrix for obtaining composites with desirable characteristics such as for surface plasmon resonance, which can be used in photonics and sensing, and controlled surface electrical conductivity. We have investigated nanocomposites produced by metal ion implantation into insulating substrates, where the implanted metal self-assembles into nanoparticles. The nanoparticles nucleate near the maximum of the implantation depth profile (projected range), which can be estimated by computer simulation using the TRIDYN code. TRIDYN is a Monte Carlo simulation program based on the TRIM (Transport and Range of Ions in Matter) code that takes into account compositional changes in the substrate due to two factors: previously implanted dopant atoms, and sputtering of the substrate surface. Our study show that the nanoparticles form a bidimentional array buried a few nanometers below the substrate surface. We have studied Au/PMMA (polymethylmethacrylate), Pt/PMMA, Ti/alumina and Au/alumina systems. Transmission electron microscopy of the implanted samples show that metallic nanoparticles form in the insulating matrix. These nanocomposites have been characterized by measuring the resistivity of the composite layer as a function of the implantation dose. The experimental results are compared with a model based on percolation theory, in which electron transport through the composite is explained by conduction through a random resistor network formed by the metallic nanoparticles. Excellent agreement is found between the experimental results and the predictions of the theory. We conclude in that the conductivity process is due only to percolation (when the conducting elements are in geometric contact) and that the contribution from tunneling conduction is negligible.

  20. An Aqueous Metal-ion Capacitor with Oxidised Carbon Nanotubes and Metallic Zinc Electrodes

    Yuheng Tian


    Full Text Available An aqueous metal ion capacitor comprising of a zinc anode, an oxidized carbon nanotubes (oCNTs cathode and a zinc sulfate electrolyte is reported. Since the shuttling cation is Zn2+, this typical metal ion capacitor is named as zinc-ion capacitor (ZIC. The ZIC integrates the divalent zinc stripping/plating chemistry with the surface-enabled pseudocapacitive cation adsorption/desorption on oCNTs. The surface chemistry and crystallographic structure of oCNTs were extensively characterized by combining X-ray photoelectron spectroscopy, Fourier-transformed infrared spectroscopy, Raman spectroscopy and X-ray powder diffraction. The function of the surface oxygen groups in surface cation storage was elucidated by a series of electrochemical measurement and the surface-enabled ZIC showed better performance than the ZIC with an un-oxidized CNT cathode. The reaction mechanism at the oCNT cathode involves the additional reversible Faradaic process, while the CNTs merely show electric double layer capacitive behavior involving a non-Faradaic process. The aqueous hybrid ZIC comprising the oCNT cathode exhibited a specific capacitance of 20 mF cm-2 (corresponding to 53 F g-1 in the range of 0-1.8 V at 10 mV s-1 and a stable cycling performance up to 5000 cycles.

  1. Ion mobility studies of carbohydrates as group I adducts: isomer specific collisional cross section dependence on metal ion radius.

    Huang, Yuting; Dodds, Eric D


    Carbohydrates play numerous critical roles in biological systems. Characterization of oligosaccharide structures is essential to a complete understanding of their functions in biological processes; nevertheless, their structural determination remains challenging in part due to isomerism. Ion mobility spectrometry provides the means to resolve gas phase ions on the basis of their shape-to-charge ratios, thus providing significant potential for separation and differentiation of carbohydrate isomers. Here, we report on the determination of collisional cross sections for four groups of isomeric carbohydrates (including five isomeric disaccharides, four isomeric trisaccharides, two isomeric pentasaccharides, and two isomeric hexasaccharides) as their group I metal ion adducts (i.e., [M + Li](+), [M + Na](+), [M + K](+), [M + Rb](+), and [M + Cs](+)). In all, 65 collisional cross sections were measured, the great majority of which have not been previously reported. As anticipated, the collisional cross sections of the carbohydrate metal ion adducts generally increase with increasing metal ion radius; however, the collisional cross sections were found to scale with the group I cation size in isomer specific manners. Such measurements are of substantial analytical value, as they illustrate how the selection of charge carrier influences carbohydrate ion mobility determinations. For example, certain pairs of isomeric carbohydrates assume unique collisional cross sections upon binding one metal ion, but not another. On the whole, these data suggest a role for the charge carrier as a probe of carbohydrate structure and thus have significant implications for the continued development and application of ion mobility spectrometry for the distinction and resolution of isomeric carbohydrates.

  2. Cognate and noncognate metal ion coordination in metal-specific metallothioneins: the Helix pomatia system as a model.

    Palacios, Oscar; Pérez-Rafael, Sílvia; Pagani, Ayelen; Dallinger, Reinhard; Atrian, Sílvia; Capdevila, Mercè


    The Helix pomatia metallothionein (MT) system, namely, its two highly specific forms, HpCdMT and HpCuMT, has offered once again an optimum model to study metal-protein specificity. The present work investigates the most unexplored aspect of the coordination behavior of MT polypeptides with respect to either cognate or noncognate metal ions, as opposed to the standard studies of cognate metal ion coordination. To this end, we analyzed the in vivo synthesis of the corresponding complexes with their noncognate metals, and we performed a detailed spectroscopic and spectrometric study of the Zn(2+)/Cd(2+) and Zn(2+)/Cu(+) in vitro replacement reactions on the initial Zn-HpMT species. An HpCuMTAla site-directed mutant, exhibiting differential Cu(+)-binding abilities in vivo, was also included in this study. We demonstrate that when an MT binds its cognate metal, it yields well-folded complexes of limited stoichiometry, representative of minimal-energy conformations. In contrast, the incorporation of noncognate metal ions is better attributed to an unspecific reaction of cysteinic thiolate groups with metal ions, which is dependent on their concentration in the surrounding milieu, where no minimal-energy structure is reached, and otherwise, the MT peptide acts as a multidentate ligand that will bind metal ions until its capacity has been saturated. Additionally, we suggest that previous binding of an MT polypeptide with its noncognate metal ion (e.g., binding of Zn(2+) to the HpCuMT isoform) may preclude the correct folding of the complex with its cognate metal ion.

  3. Solvent and metal ion effects on the conformation of cyclosporin

    Shaw, R. A.; Mantsch, Henry H.; Chowdhry, Babur Z.


    Infrared spectra of cyclosporin A (CsA) and three analogues CsC, CsD, and CsH have been measured (1) in a variety of organic solvents, and (2) in acetonitrile in the presence of lithium, sodium, magnesium, and calcium ions. The amide I (CequalsO stretching) absorption pattern shows a systematic trend with increasing solvent polarity. The spectral changes indicate that polar solvents disrupt two of the four intramolecular hydrogen bonds, leaving the first two hydrogen bonds of the (beta) -sheet structure intact. Interaction of CsA, CsC, or CsD with the monovalent cations Li+ and Na+ in acetonitrile yields spectra that are virtually identical to one another. The spectra suggest that several carbonyl groups bind simultaneously to the metal ion. In contrast the spectra suggest strong binding by Ca2+ and Mg2+ to one or two specific CequalsO groups, as evidenced by very low frequency CequalsO stretching bands observed at ca. 1600 cm-1.

  4. Development of an Electrochemical Metal-Ion Biosensor Using Self-Assembled Peptide Nanofibrils

    Viguier, Bruno; Zor, Kinga; Kasotakis, Emmanouil


    This article describes the combination of self-assembled peptide nanofibrils with metal electrodes for the development of an electrochemical metal-ion biosensor. The biological nanofibrils were immobilized on gold electrodes and used as biorecognition elements for the complexation with copper ion...

  5. "Anion clamp" allows flexible protein to impose coordination geometry on metal ions.

    Wang, Minji; Lai, Tsz Pui; Wang, Li; Zhang, Hongmin; Yang, Nan; Sadler, Peter J; Sun, Hongzhe


    X-ray crystal structures of human serum transferrin (77 kDa) with Yb(III) or Fe(III) bound to the C-lobe and malonate as the synergistic anion show that the large Yb(III) ion causes the expansion of the metal binding pocket while octahedral metal coordination geometry is preserved, an unusual geometry for a lanthanide ion.

  6. Effects of Lability of Metal Complex on Free Ion Measurement Using DMT

    Weng, L.P.; Riemsdijk, van W.H.; Temminghoff, E.J.M.


    Very low concentrations of free metal ion in natural samples can be measured using the Donnan membrane technique (DMT) based on ion transport kinetics. In this paper, the possible effects of slow dissociation of metal complexes on the interpretation of kinetic DMT are investigated both theoretically

  7. Metal Ions Removal Using Nano Oxide Pyrolox™ Material

    Gładysz-Płaska, A.; Skwarek, E.; Budnyak, T. M.; Kołodyńska, D.


    The paper presents the use of Pyrolox™ containing manganese nano oxides used for the removal of Cu(II), Zn(II), Cd(II), and Pb(II) as well as U(VI) ions. Their concentrations were analyzed using the atomic absorption spectrometer SpectrAA 240 FS (Varian) as well as UV-vis method. For this purpose the static kinetic and equilibrium studies were carried out using the batch technique. The effect of solution pH, shaking time, initial metal ion concentrations, sorbent dosage, and temperature was investigated. The equilibrium data were analyzed using the sorption isotherm models proposed by Freundlich, Langmuir-Freundlich, Temkin, and Dubinin-Radushkevich. The kinetic results showed that the pseudo second order kinetic model was found to correlate the experimental data well. The results indicate that adsorption of Cu(II), Zn(II), Cd(II), and Pb(II) as well as U(VI) ions is strongly dependent on pH. The value of pH 4-7 was optimal adsorption. The time to reach the equilibrium was found to be 24 h, and after this time, the sorption percentage reached about 70%. Kinetics of Cu(II), Zn(II), Cd(II), Pb(II), and U(VI) adsorption on the adsorbent can be described by the pseudo second order rate equation. Nitrogen adsorption/desorption, infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) measurements for adsorbent characterization were performed. Characteristic points of the double layer determined for the studied Pyrolox™ sample in 0.001 mol/dm3 NaCl solution are pHPZC = 4 and pHIEP < 2.

  8. Reactions of metal ions at surfaces of hydrous iron oxide

    Hem, J.D.


    Cu, Ag and Cr concentrations in natural water may be lowered by mild chemical reduction involving ferric hydroxide-ferrous ion redox processes. V and Mo solubilities may be controlled by precipitation of ferrous vanadate or molybdate. Concentrations as low as 10-8.00 or 10-9.00 M are readily attainable for all these metals in oxygen-depleted systems that are relatively rich in Fe. Deposition of manganese oxides such as Mn3O4 can be catalyzed in oxygenated water by coupling to ferrous-ferric redox reactions. Once formed, these oxides may disproportionate, giving Mn4+ oxides. This reaction produces strongly oxidizing conditions at manganese oxide surfaces. The solubility of As is significantly influenced by ferric iron only at low pH. Spinel structures such as chromite or ferrites of Cu, Ni, and Zn, are very stable and if locally developed on ferric hydroxide surfaces could bring about solubilities much below 10-9.00 M for divalent metals near neutral pH. Solubilities calculated from thermodynamic data are shown graphically and compared with observed concentrations in some natural systems. ?? 1977.

  9. Polyazulene based materials for heavy metal ions detection

    Oprisanu, A.; Ungureanu, E. M.; Isopescu, R.; Birzan, L.; Mihai, M.; Vasiliu, C.


    Azulene is a special monomer used to functionalize electrodes, due to its spontaneous electron drift from the seven-membered ring to the five-membered ring. The seven-membered ring of the molecule may act as electron acceptor, while the five-membered ring - as electron donor. This leads to very attractive properties for the synthesis of functional advanced materials like: materials with nonlinear optical and photorefractive properties, cathode materials for lithium batteries, or light emitting diodes based on organic materials. Azulene derivatives have been used rarely to the metal ions electroanalysis. Our study concerns the synthesis and electrochemical characterization of a new azulene based monomer 4-(azulen-1-yl)-2,6-bis((E)-2-(thiophen-3-yl)vinyl)pyridine (L). L has been used to obtain modified electrodes by electrochemical polymerization. PolyL films modified electrodes have been characterized by cyclic voltammetry in ferrocene solutions. The complexing properties of polyL based functional materials have been investigated towards heavy metals (Pb, Cd Hg, Cu) by preconcentration - anodic stripping technique in order to analyze the content of these cations from water samples.

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

    Cram, D. J.


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

  11. Interaction of lactic acid bacteria with metal ions: opportunities for improving food safety and quality.

    Mrvčić, Jasna; Stanzer, Damir; Solić, Ema; Stehlik-Tomas, Vesna


    Certain species of lactic acid bacteria (LAB), as well as other microorganisms, can bind metal ions to their cells surface or transport and store them inside the cell. Due to this fact, over the past few years interactions of metal ions with LAB have been intensively investigated in order to develop the usage of these bacteria in new biotechnology processes in addition to their health and probiotic aspects. Preliminary studies in model aqueous solutions yielded LAB with high absorption potential for toxic and essential metal ions, which can be used for improving food safety and quality. This paper provides an overview of results obtained by LAB application in toxic metal ions removing from drinking water, food and human body, as well as production of functional foods and nutraceutics. The biosorption abilities of LAB towards metal ions are emphasized. The binding mechanisms, as well as the parameters influencing the passive and active uptake are analyzed.

  12. Protein-responsive assemblies from catechol-metal ion supramolecular coordination.

    Yuan, C; Chen, J; Yu, S; Chang, Y; Mao, J; Xu, Y; Luo, W; Zeng, B; Dai, L


    Supramolecular self-assembly driven by catechol-metal ion coordination has gained great success in the fabrication of functional materials including adhesives, capsules, coatings and hydrogels. However, this route has encountered a great challenge in the construction of nanoarchitectures in the absence of removable templates, because of the uncontrollable crosslinking of catechol-metal ion coordination. Herein, we show that a supramolecular approach, combining both catechol-metal ion coordination and polymer self-assembly together, can organize polymers into hybrid nanoassemblies ranging from solid particles, homogeneous vesicles to Janus vesicles. Without the introduction of a specific binding ligand or complicated molecular design, these assemblies can totally disassemble in response to proteins. UV/vis absorption, fluorescence quenching and recovery investigations have confirmed that proteins can seize metal ions from the hybrid nanoassemblies, thus causing the degradation of catechol-metal ion coordination networks.

  13. Electrochemical Metal Ion Sensors. Exploiting Amino Acids and Peptides as Recognition Elements

    Wenrong Yang


    Full Text Available Amino acids and peptides are known to bind metal ions, in some cases very strongly. There are only a few examples of exploiting this binding in sensors. The review covers the current literature on the interaction of peptides and metals and the electrochemistry of bound metal ions. Peptides may be covalently attached to surfaces. Of particular interest is the attachment to gold via sulfur linkages. Sulfur-containing peptides (eg cysteine may be adsorbed directly, while any amino group can be covalently attached to a carboxylic acid-terminated thiol. Once at a surface, the possibility for using the attached peptide as a sensor for metal ions becomes realised. Results from the authors’ laboratory and elsewhere have shown the potential for selective monitoring of metal ions at ppt levels. Examples of the use of poly-aspartic acid and the copper binding peptide Gly-Gly-His for detecting copper ions are given.

  14. Metal ion transport quantified by ICP-MS in intact cells

    Figueroa, Julio A. Landero; Stiner, Cory A.; Radzyukevich, Tatiana L.; Heiny, Judith A.


    The use of ICP-MS to measure metal ion content in biological tissues offers a highly sensitive means to study metal-dependent physiological processes. Here we describe the application of ICP-MS to measure membrane transport of Rb and K ions by the Na,K-ATPase in mouse skeletal muscles and human red blood cells. The ICP-MS method provides greater precision and statistical power than possible with conventional tracer flux methods. The method is widely applicable to studies of other metal ion transporters and metal-dependent processes in a range of cell types and conditions. PMID:26838181

  15. Interacion of Heavy Metal Ions with C-Phycocyanin: Binding Isotherms and Cooperative Effects

    Gelagutashvili, Eteri


    The binding constant of copper(II) ions to C-PC were determined at different ionic strengths from binding isotherms by equilibrium dialysis and flame atomic absorption spectroscopy. Fluorescence and absorbtion spectroscopy provides insight of metal-C-phycocyanin interactions. Fluorescence measurements demonstrate C-PC quenching of heavy metal ions emission intensities. Stern-Volmer quenching constants were obtained from the linear quenching plots. Blue shifts in the fluorescence spectra were observed during metal binding to C-PC. It was shown, that between bound metal ions in C-PC there exists positive cooperativity.

  16. Sunflower stalks as adsorbents for the removal of metal ions from wastewater

    Sun, G.; Shi, W. [Univ. of California, Davis, CA (United States). Div. of Textiles and Clothing


    Sunflower stalks as adsorbents for the removal of metal ions such as copper, cadmium, zinc, and chromium ions in aqueous solutions were studied with equilibrium isotherms and kinetic adsorptions. The maximum adsorptions of four heavy metals are 29.3 mg/g (Cu{sup 2+}), 30.73 mg/g (Zn{sup 2+}), 42.18 mg/g (Cd{sup 2+}), and 25.07 mg/g (Cr{sup 3+}), respectively. Particle sizes of sunflower stalks affected the adsorption of metal ions; the finer size of particles showed better adsorption to the ions. Temperature also plays an interesting role in the adsorption of different metal ions. Copper, zinc, and cadmium exhibited lower adsorption on sunflower stalks at higher temperature, while chromium showed the opposite phenomenon. The adsorption rates of copper, cadmium, and chromium are quite rapid. Within 60 min of operation about 60--80% of these ions were removed from the solutions.

  17. Conversion of agonist site to metal-ion chelator site in the beta(2)-adrenergic receptor

    Elling, C E; Thirstrup, K; Holst, Birgitte


    in the mutant receptors not by normal catecholamine ligands but instead either by free zinc ions or by zinc or copper ions in complex with small hydrophobic metal-ion chelators. Chelation of the metal ions by small hydrophobic chelators such as phenanthroline or bipyridine protected the cells from the toxic......Previously metal-ion sites have been used as structural and functional probes in seven transmembrane receptors (7TM), but as yet all the engineered sites have been inactivating. Based on presumed agonist interaction points in transmembrane III (TM-III) and -VII of the beta(2)-adrenergic receptor......, in this paper we construct an activating metal-ion site between the amine-binding Asp-113 in TM-III-or a His residue introduced at this position-and a Cys residue substituted for Asn-312 in TM-VII. No increase in constitutive activity was observed in the mutant receptors. Signal transduction was activated...

  18. Metal salts for molecular ion yield enhancement in organic secondary ion mass spectrometry: a critical assessment.

    Delcorte, A; Bertrand, P


    In a search for molecular ion signal enhancement in organic SIMS, the efficiency of a series of organic and inorganic salts for molecular cationization has been tested using a panel of nonvolatile molecules with very different chemical characteristics (leucine enkephalin, Irganox 1010, tetraphenylnaphthalene, polystyrene). The compounds used for cationization include alkali bromide and group Ib metal salts (XBr with X = Li, Na, K; CF3CO2Ag; AgNO3; [CH3COCH=C(O-)CH3]2Cu; AuCl3). Alkali ions, very good for polar molecule cationization, prove to be of limited interest for nonpolar molecules such as polystyrene. Silver trifluoroacetate displays excellent results for all the considered molecules, except for leucine enkephalin (which might be due to the use of different solvents for the analyte and the salt). Instead, silver nitrate mixed with leucine enkephalin in an ethanol solution provides intense molecular signals. The influence of the respective concentrations of analyte and salt in solution, of the silver trifluoroacetate solution stability, and of the sample microstructure on the secondary ion intensities are also investigated. The results of other combinations of analyte and salts are reported. Finally, the use of salts is critically compared to other sample preparation procedures previously proposed for SIMS analysis of large organic molecules.

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

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


    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.

  20. Importance of diffuse metal ion binding to RNA.

    Tan, Zhi-Jie; Chen, Shi-Jie


    RNAs are highly charged polyanionic molecules. RNA structure and function are strongly correlated with the ionic condition of the solution. The primary focus of this article is on the role of diffusive ions in RNA folding. Due to the long-range nature of electrostatic interactions, the diffuse ions can contribute significantly to RNA structural stability and folding kinetics. We present an overview of the experimental findings as well as the theoretical developments on the diffuse ion effects in RNA folding. This review places heavy emphasis on the effect of magnesium ions. Magnesium ions play a highly efficient role in stabilizing RNA tertiary structures and promoting tertiary structural folding. The highly efficient role goes beyond the mean-field effect such as the ionic strength. In addition to the effects of specific ion binding and ion dehydration, ion-ion correlation for the diffuse ions can contribute to the efficient role of the multivalent ions such as the magnesium ions in RNA folding.

  1. Nanometer structure and conductor mechanism of polymer modified by metal ion implantation

    吴瑜光; 张通和; 张燕文; 张荟星; 张孝吉; 周固


    Polyethylene terephthalate (PET) has been modified by Ag, Ti, Cu and Si ion implanta-tion with a dose ranging from 1 × l016 to 2 x 1017 ions/cm2 using a metal vapor vacuum arc (MEVVA)source. The electrical properties of PET have been improved by metal ion implantation. The resistivityof implanted PET decreased obviously with an increase in ion dose. The results show that the conduc-tive behavior of a metal ion implanted sample is different from Si-implantation samples. In order to un-derstant the mechanism of electrical conduction, the structures of implanted layer were observed in de-tail by XRD and TEM. The nano carbon particles were dispersed in implanted PET. The nano metallicparticles were built up in metallic ion implanted layers with dose range from 1 × 1016 to 1 x 1017 ions/cm2. The nanometer metal net structure was formed in implanted layer when a dose of 2 x 1017ions/cm2 is reached. Anomalous fractal growths were observed. These surface structure changes revealedconducting mechanism evolution, lt is believed that the change would result in an improvement of theconductive properties. The conducting mechanism will be changed with increasing metal ion dose.

  2. Heterocyclic ring based colorimetric and fluorescent chemosensor for transition metal ions in an aqueous medium

    Udhayakumari, Duraisamy [Department of Chemistry, Organic and Polymer Synthesis Laboratory, National Institute of Technology, Tiruchirappalli 620015 (India); Velmathi, Sivan, E-mail: [Department of Chemistry, Organic and Polymer Synthesis Laboratory, National Institute of Technology, Tiruchirappalli 620015 (India); Boobalan, Maria susai [Department of Chemistry, St. Joseph' s College (Autonomous), Tiruchirappalli 620002 (India); Venkatesan, Parthiban; Wu, Shu-Pao [Department of Applied Chemistry, National Chiao Tung University, Hsinchu 300, Taiwan, ROC (China)


    Heterocyclic ring based R1–R3 have been synthesized from the simple condensation method. R1–R3 exhibit highly selective and sensitive recognition towards transition metal ions in an aqueous medium via visual color change and were further confirmed by UV–vis and fluorescent spectroscopic methods. Fluorescent turn on and turn off behavior was observed for receptors tested with transition metal ions. The interaction of transition metal ions and receptors R1–R3 was confirmed to adopt 1:1 binding stoichiometry. Micromolar detection limit was found for R1–R3 with metal ions. DFT theoretical calculations were employed to understand the sensing mechanism of the sensors towards the metal ions. R1 and R2 were also successfully demonstrated as a fluorescent probe for detecting Cu{sup 2+} ions in living cells. - highlights: • R1–R3 act as colorimetric and fluorescent sensors for metal ions. • Receptors (R1–R3) detect Cu{sup 2+} ions in aqueous solution at nanomolar levels. • R1 and R2 act as a fluorescent probe for detecting Cu{sup 2+} ions in living cells.

  3. Clinical and radiobiological advantages of single-dose stereotactic light-ion radiation therapy for large intracranial arteriovenous malformations. Technical note.

    Andisheh, Bahram; Brahme, Anders; Bitaraf, Mohammad A; Mavroidis, Panayiotis; Lind, Bengt K


    Radiation treatment of large arteriovenous malformations (AVMs) remains difficult and not very effective, even though seemingly promising methods such as staged volume treatments have been proposed by some radiation treatment centers. In symptomatic patients harboring large intracranial AVMs not amenable to embolization or resection, single-session high-dose stereotactic radiation therapy is a viable option, and the special characteristics of high-ionization-density light-ion beams offer several treatment advantages over photon and proton beams. These advantages include a more favorable depth-dose distribution in tissue, an almost negligible lateral scatter of the beam, a sharper penumbra, a steep dose falloff beyond the Bragg peak, and a higher probability of vascular response due to high ionization density and associated induction of endothelial cell proliferation and/or apoptosis. Carbon ions were recently shown to be an effective treatment for skull-base tumors. Bearing that in mind, the authors postulate that the unique physical and biological characteristics of light-ion beams should convey considerable clinical advantages in the treatment of large AVMs. In the present meta-analysis the authors present a comparison between light-ion beam therapy and more conventional modalities of radiation treatment with respect to these lesions. Dose-volume histograms and data on peripheral radiation doses for treatment of large AVMs were collected from various radiation treatment centers. Dose-response parameters were then derived by applying a maximum likelihood fitting of a binomial model to these data. The present binomial model was needed because the effective number of crucial blood vessels in AVMs (the number of vessels that must be obliterated to effect a cure, such as large fistulous nidus vessels) is low, making the Poisson model less suitable. In this study the authors also focused on radiobiological differences between various radiation treatments. Light-ion

  4. Effect of Some Metal Ion Dopants on Electrochemical Properties of Ni(OH)2 Film Electrode

    ZHANG Heng-bin; LIU Han-san; CAO Xue-jing; SUN Chia-chung


    The Ni(OH)2 film electrodes doped respectively with alkali-earth metal aluminum, lead, partial transition metal and some rare-earth metal(altogether 17 kinds of metals) ions were prepared by cathode electrodeposition. The electrode reaction reversibility, the difficult extent of oxygen evolution, the proton diffusion coefficient, the discharge potential of middle value and the active material utilization of the Ni(OH)2 film electrode were compared with those of the ones doped with the metal ions by means of cyclic voltammetry, potential step and constant current charge-discharge experiments. It was found that Ca2+, Co2+, Cd2+, Al3+ etc. have obviously positive effect.

  5. Measurement of free heavy metal ion concentrations in soils using Donnan membrane technique

    YI Li; HONG Yetang; WENG Liping; ZHU Yongxuan


    In natural systems heavy metals are present in very low concentrations (less than micro-molar), so precise measurement of the free metal ions is difficult. Recently, a new method has been developed called the Donnan membrane technique (DMT). Several heavy metals could be measured simultaneously using this method. Furthermore, all the metals did not interfere with each other, and the balance between the measured system and the surrounding condition could not be disturbed. Improvements were made according to the internal condition. The free heavy metal ion concentrations were measured in different systems using the improved method, and satisfied results have been obtained.

  6. Metal-on-metal bearings in total hip arthroplasties : Influence of cobalt chromium ions on bacterial growth and biofilm formation

    Hosman, Anton H.; van der Mei, Henny C.; Bulstra, Sjoerd K.; Busscher, Henk J.; Neut, Danielle


    Metal-on-metal (MOM) bearings involving cobalt-chromium (Co-Cr) alloys in total hip arthroplasties are becoming more and more popular due to their low wear. Consequences of corrosion products of Co-Cr alloys are for the most part unclear, and the influence of cobalt and chromium ions on biofilm form

  7. The effect of metal ions on the photophysical and photochemical property of phenylthio bromo metal phthalocyanines

    Pan, Sujuan; Shen, Pingping; Ma, Dongdong; Wang, Yuhua; Zhang, Tiantian; Chen, Kuizhi; Yang, Hongqin; Xie, Shusen; Peng, Yiru


    Phthalocyanines have attracted great attention because of their applications in material science including electro-optical devices, electrochromic display, and photodynamic therapy (PDT) of cancer. In addition, the Pcs exhibit great flexibility of chemical structure modification enabled by either peripheral substituents or metal ions co-ordination to central cavity of highly conjugated tetrapyrrolic macrocycles. However, because of the hydrophobic nature of the phthalocyanine ring, Pcs have strong tendency to aggregate in solution, which limited their applications. To overcome this problem, the introduction of dendritic wedge to peripheral positions of phthalocyanines can prevent the formation of aggregation to some extent. The preparation procedure involved the modification of the zinc (II) and magnesium (II) phthalocyanines with peripherally dendritic substitutions. The photophysical and photochemical properties of dendritic phthalocyanines were studied by UV/Vis and fluorescence spectroscopic methods. Compared with the magnesium (II) phthalocyanine, the intensity of Q band of zinc (II) phthalocyanine was increased but no obviously position changes was observed. Furthermore, the zinc (II) phthalocyanine exhibited relatively higher fluorescence intensity than the magnesium (II) phthalocyanine. The fluorescence quantum yield and lifetimes of magnesium (II) phthalocyanine was clearly longer than that of zinc (II) phthalocyanine. As the better photosensitizer, the zinc (II) phthalocyanine has higher singlet oxygen quantum yield owning superior performance. This results indicated that the singlet oxygen quantum yield would be effected by the nature of metal ions.

  8. Maximum occurrence analysis of protein conformations for different distributions of paramagnetic metal ions within flexible two-domain proteins.

    Luchinat, Claudio; Nagulapalli, Malini; Parigi, Giacomo; Sgheri, Luca


    Multidomain proteins are composed of rigid domains connected by (flexible) linkers. Therefore, the domains may experience a large degree of reciprocal reorientation. Pseudocontact shifts and residual dipolar couplings arising from one or more paramagnetic metals successively placed in a single metal binding site in the protein can be used as restraints to assess the degree of mobility of the different domains. They can be used to determine the maximum occurrence (MO) of each possible protein conformation, i.e. the maximum weight that such conformations can have independently of the real structural ensemble, in agreement with the provided restraints. In the case of two-domain proteins, the metal ions can be placed all in the same domain, or distributed between the two domains. It has been demonstrated that the quantity of independent information for the characterization of the system is larger when all metals are bound in the same domain. At the same time, it has been shown that there are practical advantages in placing the metals in different domains. Here, it is shown that distributing the metals between the domains provides a tool for defining a coefficient of compatibility among the restraints obtained from different metals, without a significant decrease of the capability of the MO values to discriminate among conformations with different weights.

  9. Retention behavior of amino acids and peptides on protoporphyrin-silica stationary phases with varying metal ion centers.

    Xiao, J; Meyerhoff, M E


    Various metalloprotoporphyrins (MProP) covalently linked to silica supports are examined as novel immobilized metal ion affinity chromatography (IMAC) stationary phases for separations of amino acids/peptides. Under reversed-phase HPLC conditions, the MProP-silicas exhibit high affinity toward L-histidine via metal-nitrogen axial ligation interactions, with an increasing degree of histidine retention highly dependent on the specific metal ion (M) in the center of the protoporphyrin (ProP) structure: Fe(III) > Ni(II) > Cu(II) > Zn (II) approximately Cd(II). Aromatic amino acids (i.e., L-trytophan and L-phenylalanine) are also retained on MProP columns through pi-pi interactions with the immobilized porphyrins, with the greatest affinity for L-trytophan observed on CuProP-silica columns. Peptides rich in L-histidine and L-tryptophan residues are selectively retained on most of the MProP-silica phases examined; however, the addition of an organic modifier and/or lowering the pH of the mobile phase can be used independently to attenuate the pi-pi and metal ion-nitrogen ligation interactions, respectively. Reproducible separations of His-Phe and trytophan releasing hormone are achieved on a FeProP-silica column even after extensive washing with 50 mM EDTA, demonstrating a fundamental advantage of the new MProP-silica over existing IMAC stationary phases, in which the metal ion is anchored weakly to the support via immobilized iminodiacetate and related ligands.

  10. Metal ions removal from polluted waters by sorption onto exhausted coffee waste. Application to metal finishing industries wastewater treatment

    Liu, Chang


    A new technology for Cr(VI) and divalent metal ions removal based on metal sorption onto exhausted coffee waste has been developed. Physical and chemical characterization of exhausted coffee waste was explored as well as the role of structural and non structural compounds of the waste in metal ions sorption. Kinetics of Cr(VI) sorption from binary mixtures containing different Cr(VI) and Cu(II) molar ratios were carried out in a batch reactor. A synergistic effect of Cu(II) in Cr(VI) reductio...

  11. A new strategy to stabilize oxytocin in aqueous solutions : I. The effects of divalent metal ions and citrate buffer

    Avanti, Christina; Amorij, Jean-Pierre; Setyaningsih, Dewi; Hawe, Andrea; Jiskoot, Wim; Visser, Jan; Kedrov, Alexej; Driessen, Arnold J. M.; Hinrichs, Wouter L. J.; Frijlink, Henderik W.

    In the current study, the effect of metal ions in combination with buffers (citrate, acetate, pH 4.5) on the stability of aqueous solutions of oxytocin was investigated. Both monovalent metal ions (Na+and K+) and divalent metal ions (Ca2+, Mg2+, and Zn2+) were tested all as chloride salts. The

  12. A new strategy to stabilize oxytocin in aqueous solutions : I. The effects of divalent metal ions and citrate buffer

    Avanti, Christina; Amorij, Jean-Pierre; Setyaningsih, Dewi; Hawe, Andrea; Jiskoot, Wim; Visser, Jan; Kedrov, Alexej; Driessen, Arnold J. M.; Hinrichs, Wouter L. J.; Frijlink, Henderik W.


    In the current study, the effect of metal ions in combination with buffers (citrate, acetate, pH 4.5) on the stability of aqueous solutions of oxytocin was investigated. Both monovalent metal ions (Na+and K+) and divalent metal ions (Ca2+, Mg2+, and Zn2+) were tested all as chloride salts. The effec

  13. Effects of lability of metal complex on free ion measurement using DMT.

    Weng, Liping; Van Riemsdijk, Willem H; Temminghoff, Erwin J M


    Very low concentrations of free metal ion in natural samples can be measured using the Donnan membrane technique (DMT) based on ion transport kinetics. In this paper, the possible effects of slow dissociation of metal complexes on the interpretation of kinetic DMT are investigated both theoretically and experimentally. The expressions of the lability parameter, Lgrangian , were derived for DMT. Analysis of new experimental studies using synthetic solution containing NTA as the ligand and Cu(2+) ions shows that when the ionic strength is low (DMT measurement. In natural waters, dissolved organic matter (DOM) is the most important source of ligands that complex metals. By comparing the fraction of labile species measured using other dynamic sensors (DGT, GIME) in several freshwaters, it is concluded that in most waters ion transport in DMT is controlled by diffusion in the membrane. Only in very soft waters (DMT. In this case, neglecting this effect may lead to an underestimation of the free metal ion concentration measured.

  14. Sugar-metal ion interactions: the complicated coordination structures of cesium ion with D-ribose and myo-inositol.

    Hu, Haijian; Xue, Junhui; Wen, Xiaodong; Li, Weihong; Zhang, Chao; Yang, Limin; Xu, Yizhuang; Zhao, Guozhong; Bu, Xiaoxia; Liu, Kexin; Chen, Jia'er; Wu, Jinguang


    The novel cesium chloride-D-ribose complex (CsCl·C5H10O5; Cs-R) and cesium chloride-myo-inositol complex (CsCl·C6H12O6; Cs-I) have been synthesized and characterized using X-ray diffraction and FTIR, FIR, THz, and Raman spectroscopy. Cs(+) is eight-coordinated to three chloride ions, O1 and O2 from one D-ribose molecule, O1 from another D-ribose molecule, and O4 and O5 from the third D-ribose molecule in Cs-R. For one D-ribose molecule, the oxygen atom O1 in the ring is coordinated to two cesium ions as an oxygen bridge, O2 is cocoordinated with O1 to one of the two cesium ions, and O4 and O5 are coordinated to the third cesium ion, respectively. O3 does not coordinate to metal ions and only takes part in forming hydrogen bonds. One chloride ion is connected to three cesium ions. Thus, a complicated structure of Cs-D-ribose forms. For Cs-I, Cs(+) is 10-coordinated to three chloride ions, O1 and O2 from one myo-inositol molecule, O3 and O4 from another myo-inositol molecule, O5 and O6 from the third myo-inositol molecule, and O6 from the fourth myo-inositol molecule. One metal ion is connected to four ligands, and one myo-inositol is coordinated to four Cs(+) ions, which is also a complicated coordination structure. Crystal structure results, FTIR, FIR, THz, and Raman spectra provide detailed information on the structure and coordination of hydroxyl groups to metal ions in the cesium chloride-D-ribose and cesium chloride-myo-inositol complexes.

  15. Heavy-Ion-Induced Electronic Desorption of Gas from Metals

    Molvik, A W; Mahner, E; Kireeff Covo, M; Bellachioma, M C; Bender, M; Bieniosek, F M; Hedlund, E; Krämer, A; Kwan, J; Malyshev, O B; Prost, L; Seidl, P A; Westenskow, G; Westerberg, L


    During heavy-ion operation in several particle accelerators worldwide, dynamic pressure rises of orders of magnitude were triggered by lost beam ions that bombarded the vacuum chamber walls. This ion-induced molecular desorption, observed at CERN, GSI, and BNL, can seriously limit the ion beam lifetime and intensity of the accelerator. From dedicated test stand experiments we have discovered that heavy-ion-induced gas desorption scales with the electronic energy loss (dEe/dx) of the ions slowing down in matter; but it varies only little with the ion impact angle, unlike electronic sputtering.

  16. Heavy-ion induced electronic desorption of gas from metals

    Molvik, A W; Kollmus, H; Mahner, E; Covo, M K; Bellachioma, M C; Bender, M; Bieniosek, F M; Hedlund, E; Kramer, A; Kwan, J; Malyshev, O B; Prost, L; Seidl, P A; Westenskow, G; Westerberg, L


    During heavy ion operation in several particle accelerators world-wide, dynamic pressure rises of orders of magnitude were triggered by lost beam ions that bombarded the vacuum chamber walls. This ion-induced molecular desorption, observed at CERN, GSI, and BNL, can seriously limit the ion beam lifetime and intensity of the accelerator. From dedicated test stand experiments we have discovered that heavy-ion induced gas desorption scales with the electronic energy loss (dE{sub e}/d/dx) of the ions slowing down in matter; but it varies only little with the ion impact angle, unlike electronic sputtering.

  17. Institutional advantage

    Martin, Xavier

    Is there such a thing as institutional advantage—and what does it mean for the study of corporate competitive advantage? In this article, I develop the concept of institutional competitive advantage, as distinct from plain competitive advantage and from comparative institutional advantage. I first

  18. Institutional advantage

    Martin, Xavier


    Is there such a thing as institutional advantage—and what does it mean for the study of corporate competitive advantage? In this article, I develop the concept of institutional competitive advantage, as distinct from plain competitive advantage and from comparative institutional advantage. I first i

  19. Institutional advantage

    Martin, Xavier


    Is there such a thing as institutional advantage—and what does it mean for the study of corporate competitive advantage? In this article, I develop the concept of institutional competitive advantage, as distinct from plain competitive advantage and from comparative institutional advantage. I first i

  20. Heavy metal ion uptake properties of polystyrene-supported chelating polymer resins

    A Ravikumar Reddy; K Hussain Reddy


    Metal ion uptake properties of polystyrene-supported chelating polymer resins functionalized with (i) glycine, (ii) hydroxy benzoic acid, (iii) Schiff base and (iv) diethanol amine have been investigated. The effects of pH, time and initial concentration on the uptake of metal ions have been studied. The uptake of metal ion depends on pH. The resins are more selective at pH 10 for Pb(II) and Hg(II), whereas at pH 6 they are found to be Cd(II) and Cr(VI) selective. Metal ion uptake properties of resins follow Freundlich’s equation. The resins are recyclable and are therefore employed for the removal of heavy metal pollutants from industrial waste water.

  1. Electrochemical, optical and metal ion sensing properties of dithizone derivatised electrodes

    Mirkhalaf, F


    studied. Possible applications of these modified electrodes with potential control in metal ion detection are described. The electrochemical and SPR responses for the metal ion sensing by the monolayer films were compared with those of polymer films containing the same ligand. Derivatisation of electrode surfaces with ultra-thin films of organic molecules has been extensively studied for many applications in recent years. The present study is based on a new approach in the preparation and use of these electrodes for metal ion sensing. Modification of electrode surfaces with a ligand specific to heavy metal ions has been described. A new derivative of dithizone (DDz) and its secondary metal complexes have been synthesised and attached onto indium tin oxide (ITO) and gold electrodes. This was achieved by covalent bonding between carboxyl groups in DDz and terminal amine groups of molecules self-assembled on the electrode surfaces. These monolayer films were characterised by cyclic voltammetry, by in situ and ex...

  2. Adsorption Mechanisms of Heavy Metal Ions from Drinking Water by Weakly Basic Anion Exchange Resins

    赵璇; 何仕均; 杨磊


    Heavy metal micro-contaminants can be removed from water sources technologies. Weakly basic anion exchange resins offer the best ability to remove trace amounts of heavy metals with high selectivity. This paper discusses how weakly basic resins adsorb heavy metals using two different approaches. The removal of mercury, cadmium, and lead ions is based on the fundamental theory of coordination chemistry. The mechanism is not ion exchange but extractive adsorption of heavy metal salts. However, the marked preferential adsorption of chromate by weakly basic anion exchange can be explained using the traditional theory of ion exchange. A lab-scale study produced positive results for the removal of trace amounts of heavy metal ions from drinking water.

  3. Studies on the Transition Metal Ion Induced Fluorescence Enhancement of 1,8-Naphthalimide Derivatives

    WEN,Guo-Tao; ZHU,Man-Zhou; WANG,Zhuo; MENG,Xiang-Ming; HU,Hui-Yuan; GUO,Qing-Xiang


    Two fluorosensor systems have been designed and synthesized with their photophysical properties and fluorescence responses toward the transition metal ions studied. The fluorosensor was composed of 1,8-naphthalimide and 4-chloro-1,8-naphthalimide as fluorophore respectively, an amino moiety as the receptor and a hydrocarbon chain as the spacer to link the fluorophore and receptor. Fluorescence intensity of these systems is very weak due to the process of the efficient intramolecular photoinduced electron transfer (PET) in the absence of metal ions. Titration of the transition metal ions can switch on the fluorescence immediately. The intensity of released fluorescence is even higher than the expected from the consideration of the PET in these systems. It may be rationalized that the receptor bound to transition metal ions and the solvation of the fluorophore by the water molecules from the hydrated transition metal salts, may significantly cause fluorescence enhancement.

  4. Metal-Ion Metathesis and Properties of Triarylboron-Functionalized Metal-Organic Frameworks.

    Wang, Xiaoqing; Zhang, Liangliang; Yang, Jie; Dai, Fangna; Wang, Rongming; Sun, Daofeng


    An anionic metal-organic framework, H3[(Mn4Cl)3L8]⋅30H2O⋅2.5 DMF⋅5 Diox (UPC-15), was successfully prepared by the reaction of MnCl2 with tris(p-carboxylic acid)tridurylborane (H3 L) under solvothermal conditions. UPC-15 with wide-open pores (∼18.8 Å) is constructed by packing of octahedral and cuboctahedral cages, and exhibits high gas-sorption capabilities. Notably, UPC-15 shows selective adsorption of cationic dyes due to the anion framework. Moreover, the catalytic and magnetic properties were investigated, and UPC-15 can highly catalyze the cyanosilylation of aromatic aldehydes. UPC-15 exhibits the exchange of metal ions from Mn to Cu in a single-crystal-to-single-crystal manner to generate UPC-16, which could not be obtained by the direct solvothermal reaction of CuCl2 and H3L. UPC-16 exhibits similar properties for gas sorption, dye separation, and catalytic activity. However, the magnetic behaviors for UPC-15 and UPC-16 are distinct due to the metal-specific properties. Below 47 K, UPC-15 exhibits a ferromagnetic coupling but UPC-16 shows a dominant antiferromagnetic behavior.

  5. Electronic and ionic conductivity studies on microwave synthesized glasses containing transition metal ions

    Basareddy Sujatha


    Full Text Available Glasses in the system xV2O5·20Li2O·(80 − x [0.6B2O3:0.4ZnO] (where 10 ≤ x ≤ 50 have been prepared by a simple microwave method. Microwave synthesis of materials offers advantages of efficient transformation of energy throughout the volume in an effectively short time. Conductivity in these glasses was controlled by the concentration of transition metal ion (TMI. The dc conductivity follows Arrhenius law and the activation energies determined by regression analysis varies with the content of V2O5 in a non-linear passion. This non-linearity is due to different conduction mechanisms operating in the investigated glasses. Impedance and electron paramagnetic resonance (EPR spectroscopic studies were performed to elucidate the nature of conduction mechanism. Cole–cole plots of the investigated glasses consist of (i single semicircle with a low frequency spur, (ii two depressed semicircles and (iii single semicircle without spur, which suggests the operation of two conduction mechanisms. EPR spectra reveal the existence of electronic conduction between aliovalent vanadium sites. Further, in highly modified (10V2O5 mol% glasses Li+ ion migration dominates.

  6. Interaction between ATP, metal ions, glycine, and several minerals

    Rishpon, J.; Ohara, P. J.; Lawless, J. G.; Lahav, N.


    Interactions between ATP, glycine and montmorillonite and kaolinite clay minerals in the presence of various metal cations are investigated. The adsorption of adenine nucleotides on clays and Al(OH)3 was measured as a function of pH, and glycine condensation was followed in the presence of ATP, ZnCl2, MgCl2 and either kaolinite or montmorillonite. The amounts of ATP and ADP adsorbed are found to decrease with increasing Ph, and to be considerably enhanced in experiments with Mg(2+)- and Zn(2+)-montmorillonite with respect to Na(+)-montmorillonite. The effects of divalent cations are less marked in kaolinite. Results for Al(OH)3 show the importance of adsorption at clay platelet edges at high pH. The decomposition of ATP during drying at high temperature is observed to be inhibited by small amounts of clay, vacuum, or Mg(2+) or Zn(2+) ions, and to be accompanied by peptide formation in the presence of glycine. Results suggest the importance of Zn(2+) and Mg(2+) in chemical evolution.

  7. Metal ion binding with carbon nanotubes and graphene: Effect of chirality and curvature

    Umadevi, Deivasigamani; Sastry, G. Narahari


    First principles calculations have been used to comprehensively study the binding of a series alkali (Li+, Na+, K+) and alkaline earth (Be2+, Mg2+, Ca2+) metal ions with carbon nanotubes (CNTs) and graphene. It is interesting to note that the mono-cationic systems prefer binding to armchair CNTs over zigzag CNTs, while the preference for the di-cationic systems is exactly opposite. We have also observed significant changes in the HOMO-LUMO energy gap of the CNTs on metal ion binding and these results indicate that the fine tuning of energy gap of the CNTs can be effected through metal ion binding.

  8. In vitro corrosion behaviour and metallic ion release of different prosthodontic alloys.

    Gil, F J; Sánchez, L A; Espías, A; Planell, J A


    The corrosion resistance for six metallic alloys often used in clinical dentistry, was evaluated by measuring their polarisation resistance in an artificial saliva environment. The critical current density (icr), the passive current density (ip), the corrosion potential (Ecorr) and the critical pitting potential (Ecp), were studied. Metallic ion release from the different alloys was analysed in a saliva environment at 37 degrees C. The nickel-chromium alloy exhibited important corrosion and a high quantity of ions was released. The titanium presented a low value of ion release and a good corrosion resistance due to the passive film on the metal surface. The high gold content alloy provided the best corrosion resistance.

  9. Hybrid flotation--membrane filtration process for the removal of heavy metal ions from wastewater.

    Blöcher, C; Dorda, J; Mavrov, V; Chmiel, H; Lazaridis, N K; Matis, K A


    A promising process for the removal of heavy metal ions from aqueous solutions involves bonding the metals firstly to a special bonding agent and then separating the loaded bonding agents from the wastewater stream by separation processes. For the separation stage, a new hybrid process of flotation and membrane separation has been developed in this work by integrating specially designed submerged microfiltration modules directly into a flotation reactor. This made it possible to combine the advantages of both flotation and membrane separation while overcoming the limitations. The feasibility of this hybrid process was proven using powdered synthetic zeolites as bonding agents. Stable fluxes of up to 80l m(-2)h(-1) were achieved with the ceramic flat-sheet multi-channel membranes applied at low transmembrane pressure (copper, nickel and zinc, were reduced from initial concentrations of 474, 3.3 and 167mg x l(-1), respectively, to below 0.05 mg x l(-1), consistently meeting the discharge limits.

  10. Metal ion concentrations in body fluids after implantation of hip replacements with metal-on-metal bearing--systematic review of clinical and epidemiological studies.

    Albrecht Hartmann

    Full Text Available INTRODUCTION: The use of metal-on-metal (MoM total hip arthroplasty (THA increased in the last decades. A release of metal products (i.e. particles, ions, metallo-organic compounds in these implants may cause local and/or systemic adverse reactions. Metal ion concentrations in body fluids are surrogate measures of metal exposure. OBJECTIVE: To systematically summarize and critically appraise published studies concerning metal ion concentrations after MoM THA. METHODS: Systematic review of clinical trials (RCTs and epidemiological studies with assessment of metal ion levels (cobalt, chromium, titanium, nickel, molybdenum in body fluids after implantation of metalliferous hip replacements. Systematic search in PubMed and Embase in January 2012 supplemented by hand search. Standardized abstraction of pre- and postoperative metal ion concentrations stratified by type of bearing (primary explanatory factor, patient characteristics as well as study quality characteristics (secondary explanatory factors. RESULTS: Overall, 104 studies (11 RCTs, 93 epidemiological studies totaling 9.957 patients with measurement of metal ions in body fluids were identified and analyzed. Consistently, median metal ion concentrations were persistently elevated after implantation of MoM-bearings in all investigated mediums (whole blood, serum, plasma, erythrocytes, urine irrespective of patient characteristics and study characteristics. In several studies very high serum cobalt concentrations above 50 µg/L were measured (detection limit typically 0.3 µg/L. Highest metal ion concentrations were observed after treatment with stemmed large-head MoM-implants and hip resurfacing arthroplasty. DISCUSSION: Due to the risk of local and systemic accumulation of metallic products after treatment with MoM-bearing, risk and benefits should be carefully balanced preoperatively. The authors support a proposed "time out" for stemmed large-head MoM-THA and recommend a restricted

  11. Sono-electrochemical recovery of metal ions from their aqueous solutions.

    Dong, Bingfeng; Fishgold, Asher; Lee, Paul; Runge, Keith; Deymier, Pierre; Keswani, Manish


    Metal recovery from aqueous waste streams is an important goal for recycling, agriculture and mining industries. The development of more effective methods of recovery have been of increasing interest. The most common methods for metal recovery include precipitation, electrochemical, ion exchange, flocculation/coagulation and filtration. In the current work, a sono-electrochemical technique employing sound field at megasonic frequency (500kHz or 1MHz) in conjunction with electrochemistry is evaluated for enhanced recovery of selected metal ions (palladium, lead and gallium) with different redox potentials from their aqueous solutions. The surface morphology and elemental composition of the metal deposits were characterized using scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. The percent recovery was found to depend on the type of metal ion and the megasonic frequency used. Palladium was recovered in its metal form, while lead and gallium were oxidized during or after the recovery process.

  12. Laser ion acceleration from a double-layer metal foil

    Lecz, Zsolt


    The laser-ion acceleration with ultra-intense and ultra-short laser pulses has opened a new field of accelerator physics over the last decade. Fast development in laser systems are capable of delivering short pulses of a duration of a few hundred femtoseconds at intensities between 10{sup 18}-10{sup 20} W/cm{sup 2}. At these high intensities the laser-matter interaction induces strong charge separation, which leads to electric fields exceeding the acceleration gradients of conventional devices by 6 orders of magnitude. The particle dynamics and energy absorption of the laser pulse can be understood by means of high-performance simulation tools. In the framework of the LIGHT (Laser Ion Generation, Handling and Transport) project our goal is to provide an analytical description of the 3D distribution of the protons accelerated via TNSA (Target Normal Sheath Acceleration). In this acceleration mechanism the short pulse impinging on a metal foil heats the electrons to relativistic energies, which triggers the strong charge separation field on the opposite target surface (Debye-sheath). The accelerated light ions (proton, carbon, oxygen) observed in the experiments originate from the contamination layer deposited on the surface. The thickness of this layer in the experiments is not known exactly. According to our study these ions can be accelerated in three different regimes depending on layer thickness: quasi-static acceleration (QSA, for thin layers), plasma expansion (for thick layers) and a not well understood intermediate (or combined) regime. In a laser-plasma simulations time-dependent hot electron density and temperature are observed, therefore we performed plasma simulations with a well defined and constant initial hot electron distribution. Thus the simulation results are easier to compare with analytical models. In our case the theoretical investigation of the TNSA involves the understanding of the charge separation effects at the surface of a two

  13. Catalysis by alkali and alkaline-earth metal ions in nucleophilic attack of methoxide ion on crown ethers bearing an intra-annular acetoxy group

    Cacciapaglia, Roberta; Lucente, Silvia; Mandolini, Luigi; Doorn, van Arie R.; Reinhoudt, David N.; Verboom, Willem


    Rates of reaction of methoxide ion with crown ethers bearing an intra-annular acetoxy group are markedly enhanced by alkali and alkaline-earth metal bromides as a result of much stronger interactions of the metal ions with transition states than with reactants. Rates of reactions of methoxide ion w

  14. Synthesis of Bismuth-Nanoparticle-Enriched Nanoporous Carbon on Graphene for Efficient Electrochemical Analysis of Heavy-Metal Ions.

    Cui, Lin; Wu, Jie; Ju, Huangxian


    A BiNPs@NPCGS nanocomposite was designed for highly efficient detection of multiple heavy-metal ions by in situ synthesis of bismuth-nanoparticle (BiNP)-enriched nanoporous carbon (NPS) on graphene sheet (GS). The NPCGS was prepared by pyrolysis of zeolitic imidazolate framework-8 (ZIF-8) nanocrystals deposited on graphene oxide and displayed a high surface area of 1251 m(2)  g(-1) and a pore size of 3.4 nm. BiNPs were deposited on NPCGS in situ by chemical reduction of Bi(3+) with NaBH4 . Due to the restrictive effect of the pore/surface structure of NPCGS, the BiNPs were uniform and well dispersed on the NPCGS. The BiNPs@NPCGS showed good conductivity and high effective area, and the presence of BiNPs allowed it to act as an efficient material for anodic-stripping voltammetric detection of heavy-metal ions. Under optimized conditions, the BiNPs@NPCGS-based sensor could simultaneously determine Pb(2+) and Cd(2+) with detection limits of 3.2 and 4.1 nM, respectively. Moreover, the proposed sensor could also differentiate Tl(+) from Pb(2+) and Cd(2+). Owing to its advantages of simple preparation, environmental friendliness, high surface area, and fast electron-transfer ability, BiNPs@NPCGS showed promise for practical application in sensing heavy-metal ions.

  15. A Study on the Fixed-bed Adsorption of Heavy Metal Ions over Chitosan Bead

    Chung, K.H. [Department of Petrochemical Engineering, Hanlyo University, Chonnam (Korea)


    Fixed-bed adsorption of metal ions on chitosan bead was studied to remove heavy metal ions in waste water. Chitin was extracted from crab shell and chitosan was prepared by deacetylation of the chitin. The chitosan in bead was used as an adsorbent for heavy metal ions. Freundlich and Langmuir isotherm was determined from the experimental results of equilibrium adsorption for individual metal ion (Cu{sup 2+}, Co{sup 2+}, Ni{sup 2+}) on chitosan bead. Adsorption strength of metal ions decreased in the order of Cu{sup 2+}>Co{sup 2+}>Ni{sup 2+} ion. Breakthrough curves of single and multicomponent adsorption for metal ions were obtained from the experimental results of fixed-bed adsorption. The breakthrough curves were analyzed by simulation with fixed-bed adsorption equation based on LDFA (linear driving force approximation) adopted LAS (ideal adsorbed solution) theory which can predict multi-component adsorption isotherm from individual adsorption isotherm. The behavior of fixed bed adsorption for single and multi-component system could be nicely simulated by the equation. 22 refs., 10 figs., 2 tabs.

  16. The two distinctive metal ion binding domains of the wheat metallothionein Ec-1.

    Peroza, Estevão A; Kaabi, Ali Al; Meyer-Klaucke, Wolfram; Wellenreuther, Gerd; Freisinger, Eva


    Metallothioneins are small cysteine-rich proteins believed to play a role, among others, in the homeostasis of essential metal ions such as Zn(II) and Cu(I). Recently, we could show that wheat E(c)-1 is coordinating its six Zn(II) ions in form of metal-thiolate clusters analogously to the vertebrate metallothioneins. Specifically, two Zn(II) ions are bound in the N-terminal and four in the C-terminal domain. In the following, we will present evidence for the relative independence of the two domains from each other with respect to their metal ion binding abilities, and uncover three intriguing peculiarities of the protein. Firstly, one Zn(II) ion of the N-terminal domain is relative resistant to complete replacement with Cd(II) indicating the presence of a Zn(II)-binding site with increased stability. Secondly, the C-terminal domain is able to coordinate an additional fifth metal ion, though with reduced affinity, which went undetected so far. Finally, reconstitution of apoE(c)-1 with an excess of Zn(II) shows a certain amount of sub-stoichiometrically metal-loaded species. The possible relevance of these finding for the proposed biological functions of wheat E(c)-1 will be discussed. In addition, extended X-ray absorption fine structure (EXAFS) measurements on both, the full-length and the truncated protein, provide final evidence for His participation in metal ion binding.

  17. Electrochemical preparation of metal microstructures on large areas of etched ion track membranes

    Dobrev, D.; Vetter, J.; Angert, N.


    A microgalvanic method for metal filling of etched ion tracks in organic foils on large areas is described. The method and the used galvanic cell permit the deposition of stable standing individual metal whiskers with high aspect ratio and a density of 10 5-10 8 per cm 2 on an area of 12.5 cm 2. The method was verified with copper and it is suitable also for various other metals. It can be applied for the replication of etched ion tracks and for the fabrication of microstructures containing large numbers of individual metal whiskers.

  18. Process for carbonaceous material conversion and recovery of alkali metal catalyst constituents held by ion exchange sites in conversion residue

    Sharp, David W.


    In a coal gasification operation or similar conversion process carried out in the presence of an alkali metal-containing catalyst wherein solid particles containing alkali metal residues are produced, alkali metal constituents are recovered for the particles by contacting or washing them with an aqueous solution containing calcium or magnesium ions in an alkali metal recovery zone at a low temperature, preferably below about F. During the washing or leaching process, the calcium or magnesium ions displace alkali metal ions held by ion exchange sites in the particles thereby liberating the ions and producing an aqueous effluent containing alkali metal constituents. The aqueous effluent from the alkali metal recovery zone is then recycled to the conversion process where the alkali metal constituents serve as at least a portion of the alkali metal constituents which comprise the alkali metal-containing catalyst.

  19. Effect of Metal Ions on the Formation of Trichloronitromethane during Chlorination of Catechol and Nitrite.

    Gan, Guojuan; Mei, Rongwu; Qiu, Lin; Hong, Huachang; Wang, Qingjun; Mazumder, Asit; Wu, Shikai; Pan, Xiangliang; Liang, Yan


    Catechol, nitrite, and dissolved metals are ubiquitous in source drinking water. Catechol and nitrite have been identified as precursors for halonitromethanes (HNMs), but the effect of metal ions on HNM formation during chlorination remains unclear. The main objective of this study was to investigate the effect of metal ions (Fe, Ti, Al) on the formation of trichloronitromethane (TCNM) (the most representative HNM species in disinfected water) on chlorinating catechol and nitrite. Trichloronitromethane was extracted by methyl tert-butyl ether and detected by gas chromatography. The results show that metal ions promoted the formation of TCNM and that the enhancement efficiency followed the order of Fe > Ti > Al. Trichloronitromethane formation increased greatly within 2 h, and a basic condition (pH 8-9) favored TCNM formation more than acidic or neutral conditions. The conjoint effect of the metal-ion mixtures was shown to be similar to that of the single metal ion having the highest promoting effect on TCNM formation. Our results strongly suggest that metal ions play a significant role in enhancing TCNM formation.

  20. Advantageous use of metallic cobalt in the target for pulsed laser deposition of cobalt-doped ZnO films

    Ying, Minju; Blythe, Harry J.; Dizayee, Wala; Heald, Steve M.; Gerriu, Fatma M.; Fox, A. Mark; Gehring, Gillian A.


    We investigate the magnetic properties of ZnCoO thin films grown by pulsed laser deposition (PLD) from targets made containing metallic Co or CoO precursors instead of the usual Co3O4. We find that the films grown from metallic Co precursors in an oxygen rich environment contain negligible amounts of Co metal and have a large magnetization at room temperature. Structural analysis by X-ray diffraction and magneto-optical measurements indicate that the enhanced magnetism is due, in part, from Zn vacancies that partially compensate the naturally occurring n-type defects. We conclude that strongly magnetic films of Zn0.95Co0.05O that do not contain metallic cobalt can be grown by PLD from Co-metal-precursor targets if the films are grown in an oxygen atmosphere.

  1. Ion chromatography with the indirect ultraviolet detection of alkali metal ions and ammonium using imidazolium ionic liquid as ultraviolet absorption reagent and eluent.

    Liu, Yong-Qiang; Yu, Hong


    Indirect ultraviolet detection was conducted in ultraviolet-absorption-agent-added mobile phase to complete the detection of the absence of ultraviolet absorption functional group in analytes. Compared with precolumn derivatization or postcolumn derivatization, this method can be widely used, has the advantages of simple operation and good linear relationship. Chromatographic separation of Li(+) , Na(+) , K(+) , and NH4 (+) was performed on a carboxylic acid base cation exchange column using imidazolium ionic liquid/acid/organic solvent as the mobile phase, in which imidazolium ionic liquids acted as ultraviolet absorption reagent and eluting agent. The retention behaviors of four kinds of cations are discussed, and the mechanism of separation and detection are described. The main factors influencing the separation and detection were the background ultraviolet absorption reagent and the concentration of hydrogen ion in the ion chromatography-indirect ultraviolet detection. The successful separation and detection of Li(+) , Na(+) , K(+) , and NH4 (+) within 13 min was achieved using the selected chromatographic conditions, and the detection limits (S/N = 3) were 0.02, 0.11, 0.30, and 0.06 mg/L, respectively. A new separation and analysis method of alkali metal ions and ammonium by ion chromatography with indirect ultraviolet detection method was developed, and the application range of ionic liquid was expanded. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Effect of metal ions on the growth and metabolites production of ...



    Sep 26, 2011 ... The effects of several metal ions on the cell growth, production of polysaccharides by ... in vegetarian diets and regarded as medicinal food that ... Many factors including nutrition ... in submerged fermentation is relatively poor.

  3. Non-centrosymmetric behavior of a clay film ion-exchanged with chiral metal complexes.

    Suzuki, Yasutaka; Matsunaga, Ryoya; Sato, Hisako; Kogure, Toshihiro; Yamagishi, Akihiko; Kawamata, Jun


    SHG measurements on a highly transparent clay film ion-exchanged with chiral metal complexes revealed that the mono-molecular layer of the chiral complexes in an interlayer space acquired a non-centrosymmetric character.

  4. Photodetachment of negative ion in a gradient electric field near a metal surface

    Liu Tian-Qi; Wang De-Hun; Han Cai; Liu Jiang; Liang Dong-Qi; Xie Si-Cheng


    Based on closed-orbit theory,the photodetachment of Hˉ in a gradient electric field near a metal surface is studied.It is demonstrated that the gradient electric field has a significant influence on the photodetachment of negative ions near a metal surface.With the increase of the gradient of the electric field,the oscillation in the photodetachment cross section becomes strengthened.Besides,in contrast to the photodetachment of Hˉ near a metal surface in a uniform electric field,the oscillating amplitude and the oscillating region in the cross section of a gradient electric field also become enlarged.Therefore,we can use the gradient electric field to control the photodetachment of negative ions near a metal surface.We hope that our results will be useful for understanding the photodetachment of negative ions in the vicinity of surfaces,cavities,and ion traps.

  5. Growth of cyanophage N-1 under the influence of heavy metal ions.

    Sarma, T A; Kaur, Sukhrish P


    The growth of cyanophage N-1 in the cyanobacterium Nostoc muscorum under the influence of heavy metal ions, namely Co2+, Cr6+, Cu2+, Mn2+ and Ni2+ has been studied. One-step growth experiments revealed that heavy metal ions extended the latent period by 1-2 hrs with a concomitant decrease in the phage burst size. The latter was reduced in the order Cu2/Mn2+, Ni2+, Co2+ and Cr6+. The treatment of the phage-infected bacteria with heavy metal ions did not induce mutations affecting either the phage plaque morphology or burst size. The final phage titer after such a treatments was lowest with Co2+, Cu2+ and Cr6+. The inhibition of the phage growth under the influence of heavy metal ions is discussed in context with the interaction of cyanophage N-1 with the photosynthetic reactions in the host bacteria.

  6. Colorimetric chemosensor for multi-signaling detection of metal ions using pyrrole based Schiff bases.

    Udhayakumari, Duraisamy; Velmathi, Sivan


    Pyrrole based Schiff bases act as a highly sensitive probe for metal ions in aqueous medium. Both receptors R1 and R2 are sensitive towards Fe(3+), Cu(2+), Hg(2+) and Cr(3+) among the other metal ions. The sensing ability of the receptors are investigated via colorimetric, optical and emission spectroscopic studies. The binding stoichiometries of R1 and R2 with metal ions have been determined as 2:1 by using Job's plot. The colorimetric receptors exhibited high sensitivity with a low detection limit of μM levels. In the presence of metal ions both receptors shows fluorescence quenching. This might be due to the photo induced electron transfer mechanism. The quenching constant was further determined using Stern-Volmer plot.

  7. Factorial experimental design for recovering heavy metals from sludge with ion-exchange resin.

    Lee, I Hsien; Kuan, Yu-Chung; Chern, Jia-Ming


    Wastewaters containing heavy metals are usually treated by chemical precipitation method in Taiwan. This method can remove heavy metals form wastewaters efficiently, but the resultant heavy metal sludge is classified as hazardous solid waste and becomes another environmental problem. If we can remove heavy metals from sludge, it becomes non-hazardous waste and the treatment cost can be greatly reduced. This study aims at using ion-exchange resin to remove heavy metals such as copper, zinc, cadmium, and chromium from sludge generated by a PCB manufacturing plant. Factorial experimental design methodology was used to study the heavy metal removal efficiency. The total metal concentrations in the sludge, resin, and solution phases were measured respectively after 30 min reaction with varying leaching agents (citric acid and nitric acid); ion-exchange resins (Amberlite IRC-718 and IR-120), and temperatures (50 and 70 degrees C). The experimental results and statistical analysis show that a stronger leaching acid and a higher temperature both favor lower heavy metal residues in the sludge. Two-factors and even three-factor interaction effects on the heavy metal sorption in the resin phase are not negligible. The ion-exchange resin plays an important role in the sludge extraction or metal recovery. Empirical regression models were also obtained and used to predict the heavy metal profiles with satisfactory results.

  8. Occurrence of metal ions in rice produced in Uruguay

    Mario Rivero


    Full Text Available The United Nations General Assembly declared the year 2004 the International Year of Rice under the concept "Rice is Life". The largest nutritional problems occurring globally are protein-energy malnutrition, Ca, Fe, I, Zn and vitamin A deficiencies. Being rice the staple food more consumed worldwide, outstanding care is taken on its composition levels.Uruguay has emerged as medium-size rice producer and Latin America's major rice exporter, and is now amongst the world's top ten. Thus, the knowledge of toxic as well as micronutrient elements is very important. Here is reported the determination in forty nine samples of rice (Oryza sativa L. of As, Cd, Cr, and Pb by ET AAS in samples digested by dry ashing, and Ca, Co, Cu, Fe, K, Mg, Mo, Mn, Na, Ni and Zn by FAAS and Hg by CV AAS using microwave-assisted decomposition.The amount of all the metal ions studied in this work fall within the range typical of rice around the world. All the rice samples tested showed lower levels of As, Cd, Hg and Pb than the maximum limit permitted by governmental and international organizations.Potassium was the most abundant mineral followed by Mg and Ca and amongst microelements the presence of Cu, Fe, Mo, Mn, Na and Zn was outstanding.The milling process highly affects the contents of K, Mg, Mn, Na and Zn while little influence has on Ca, Co, Cu and Fe concentrations.Unexpected loss of Ca, Fe and Mn during parboiling process was detected. 

  9. Metal-carbon clusters: The origin of the delayed atomic ion

    Davis, K. M.; Peppernick, S. J.; Castleman, A. W.


    Studies of the emission of electrons from excited metal-carbon cluster systems that include the Met-Car (M8C12, where M is Ti, Zr, and V) also have revealed the evolution of a delayed atomic ion. The source of the delayed atomic ion, which involves the emission of ionized atoms on the microsecond time scale, is the focus of this investigation. By studying the delayed ionization of mixed zirconium and titanium carbon complexes produced in a laser vaporization source coupled to a time-of-flight mass spectrometer, for the first time both the zirconium and titanium delayed atomic ions were observed to be emitted in the same experiment. These studies allowed a determination that the source of the delayed atomic ion is an excited metal dicarbide. A plausible mechanism involving the excitation of a high Rydberg state of the metal dicarbide prior to an excited ion pair separation is proposed.

  10. First-principles calculations on implanted TiO2 by 3d transition metal ions


    3d transition metal (V, Cr and Fe) ions are implanted into TiO2 by the method of metal ion implantation. The electronic band structures of TiO2 films doped 3d transition metal ions have been analyzed by ab initio band calculations based on a self-consistent full-potential linearized augmented plane-wave method within the first-principle formalism. Influence of implantation on TiO2 films is examined by the method of UV-visible spectrometry. The results of experiment and calculation show that the optical band gap of TiO2 films is narrowed by ion implantation. The calculation shows that the 3d state of V, Cr and Fe ions plays a significant role in red shift of UV-Vis absorbance spectrum.

  11. Process for the conversion of sugars to lactic acid and 2-hydroxy-3-butenoic acid or esters thereof comprising a metallo-silicate material and a metal ion


    A process for the preparation of lactic acid and 2-hydroxy- 3-butenoic acid or esters thereof from a sugar in the presence of a metallo-silicate material, a metal ion and a solvent, wherein the metal ion is selected from one or more of the group consisting of potassium ions, sodium ions, lithium ...... ions, rubidium ions and caesium ions....


    范瑞溪; 狄俊伟


    This paper describes the invesligation of the transfer behaviour of the alkaline earth-metal cations across the water/nitrobenzene interface facilitated by josamycin in the nitrobenzene phase using semi-differential cyclic voltammetry .The peak height is directly proportional to the concentration of josaycin (nb) and to the potential scan rate.The complexes formed from alkaline earth-metal ions and josamycin at the w/nb interface are ML22+ ion.

  13. Study of application of hydrophobic fibrous sorbents for water purification from metal ions

    Е. V. Petrova; Astashkina, А. P.; Filonenko, D. А.; Otmakhov, V. I.; Izaak, Т. I.; Volokitin, G. G.


    Sorption properties of hydrophobic fibrous sorbents on the basis of polypropylene and polyethylene terephthalate produced from thermoplastic polymer wastes to metal ion series in aqueous media has been studied. Based on the experimental data of extraction degree dependencies on fibre laying density, dispersity, presence of air in sorbent, volume of pass solution the mechanism of metal ion sorption from aqueous media with hydrophobic fibrous materials is suggested.

  14. Coordination of cassava starch to metal ions and thermolysis of resulting complexes

    Piotr Tomasik


    Full Text Available Cassava starch formed Werner-type complexes with ions of metals from the transition groups. This was proven by conductivity and electron paramagnetic resonance measurements. The coordination of starch to central metal ions influenced the thermal decomposition of starch. As a rule complexes started to decompose at lower temperature than did starch. On the other hand, the decomposition proceeded at a lower rate than the decomposition of non-coordinated starch.

  15. Silica coated magnetite nanoparticles for removal of heavy metal ions from polluted waters

    Dash, Monika


    Magnetic removal of Hg2+ and other heavy metal ions like Cd2+, Pb2+ etc. using silica coated magnetite particles from polluted waters is a current topic of active research to provide efficient water recycling and long term high quality water. The technique used to study the bonding characteristics of such kind of nanoparticles with the heavy metal ions is a very sensitive hyperfine specroscopy technique called the perturbed angular correlation technique (PAC).

  16. Metal ions as cofactors for aggregation of therapeutic peptide salmon calcitonin.

    Rastogi, Neeraj; Mitra, Kalyan; Kumar, Dinesh; Roy, Raja


    The effects of multivalent metal ions (Cu(2+)/Zn(2+)/Al(3+)) on the aggregation of salmon calcitonin (sCT)--a therapeutic peptide used worldwide in the treatment of osteoporosis and Paget's disease--have been studied in vitro using NMR (both solution state and solid state), TEM, ThT-fluorescence, and FT-IR spectroscopy. Overall, the various results indicated that the metal-ions-induced conformational transitions in the peptide--mostly toward the β-sheet--facilitate the aggregation of sCT in solution. First, the solution NMR has been used to check the interaction between the peptide and the metal ions. Following this, the formation and characterization of calcitonin aggregates has been performed using TEM, solid state NMR, and FT-IR spectroscopy. The TEM and ThT-fluorescence results revealed that the sCT peptide incubated with Cu(2+) and Zn(2+) metal ions (in aqueous environment) forms globular aggregates, while that with Al(3+) ions forms fibrils. The solid state NMR and FT-IR studies revealed the presence of a substantial amount of β-sheet content in sCT aggregates (formed in the presence of these metal ions) compared to the monomeric sCT, indicating that the metal binding is concomitant with conformational changes. The present study becomes crucial while prescribing this drug peptide under physio-pathological conditions associated with an abnormal accumulation of metal ions (Cu(2+)/Zn(2+)/Al(3+)) in the body (i.e., abnormal metal ion homeostasis).

  17. Tuning the chemical selectivity of SWNT-FETs for detection of heavy-metal ions.

    Forzani, Erica S; Li, Xiulan; Zhang, Peiming; Tao, Nongjian; Zhang, Ruth; Amlani, Islamshah; Tsui, Raymond; Nagahara, Larry A


    A method to functionalize single-walled carbon nanotubes (SWNTs) in a field-effect transistor (FET) device for the selective detection of heavy-metal ions is presented. In this method, peptide-modified polymers were electrochemically deposited onto SWNTs and the selective detection of metal ions was demonstrated by choosing appropriate peptide sequences. The signal transduction mechanism of the peptide-modified SWNT-FETs has also been studied.

  18. The role of metal ions in X-ray induced photochemistry

    Stumpf, Vasili; Cederbaum, Lorenz S


    Metal ions play numerous important roles in biological systems being central to the function of biomolecules. In this letter we show that the absorption of X-rays by these ions leads to a complicated chain of ultrafast relaxation steps resulting in the complete degradation of their nearest environment. We conducted high quality ab initio studies on microsolvated Mg clusters demonstrating that ionisation of an 1s-electron of Mg leads to a complicated electronic cascade comprising both intra- and intermolecular steps and lasting only a few hundreds femtoseconds. The metal cation reverts to its original charge state at the end of the cascade, while the nearest solvation shell becomes multiply ionised and large concentrations of radical and slow electron species build up in the metal vicinity. We conclude that such cascades involving metal ions are essential for understanding the radiation chemistry of solutions and radiation damage to metal containing biomolecules.

  19. The connection between metal ion affinity and ligand affinity in integrin I domains

    Vorup-Jensen, Thomas; Waldron, TT; Astrof, N;


    Integrins are cell-surface heterodimeric proteins that mediate cell-cell, cell-matrix, and cell-pathogen interactions. Half of the known integrin alpha subunits contain inserted domains (I domains) that coordinate ligand through a metal ion. Although the importance of conformational changes within...... isolated I domains in regulating ligand binding has been reported, the relationship between metal ion binding affinity and ligand binding affinity has not been elucidated. Metal and ligand binding by several I domain mutants that are stabilized in different conformations are investigated using isothermal...... titration calorimetry and surface plasmon resonance studies. This work suggests an inverse relationship between metal ion affinity and ligand binding affinity (i.e. constructs with a high affinity for ligand exhibit a low affinity for metal). This trend is discussed in the context of structural studies...

  20. Interaction of antihypertensive drug amiloride with metal ions in micellar medium using fluorescence spectroscopy

    Gujar, Varsha; Pundge, Vijaykumar; Ottoor, Divya, E-mail:


    Steady state and life time fluorescence spectroscopy have been employed to study the interaction of antihypertensive drug amiloride with biologically important metal ions i.e. Cu{sup 2+}, Fe{sup 2+}, Ni{sup 2+} and Zn{sup 2+} in various micellar media (anionic SDS (sodium dodecyl sulfate), nonionic TX-100 (triton X-100) and cationic CTAB (cetyl trimethyl ammonium bromide)). It was observed that fluorescence properties of drug remain unaltered in the absence of micellar media with increasing concentration of metal ions. However, addition of Cu{sup 2+}, Fe{sup 2+} and Ni{sup 2+} caused fluorescence quenching of amiloride in the presence of anionic micelle, SDS. Binding of drug with metal ions at the charged micellar interface could be the possible reason for this pH-dependent metal-mediated fluorescence quenching. There were no remarkable changes observed due to metal ions addition when drug was present in cationic and nonionic micellar medium. The binding constant and bimolecular quenching constant were evaluated and compared for the drug–metal complexes using Stern–Volmer equation and fluorescence lifetime values. - Highlights: • Interaction of amiloride with biologically important metal ions, Fe{sup 2+}, Cu{sup 2+}, Ni{sup 2+} and Zn{sup 2+}. • Monitoring the interaction in various micelle at different pH by fluorescence spectroscopy. • Micelles acts as receptor, amiloride as transducer and metal ions as analyte in the present system. • Interaction study provides pH dependent quenching and binding mechanism of drug with metal ions.

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

    Duncan, Michael


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

  2. Divalent Metal Ion Transport across Large Biological Ion Channels and Their Effect on Conductance and Selectivity

    Elena García-Giménez


    Full Text Available Electrophysiological characterization of large protein channels, usually displaying multi-ionic transport and weak ion selectivity, is commonly performed at physiological conditions (moderate gradients of KCl solutions at decimolar concentrations buffered at neutral pH. We extend here the characterization of the OmpF porin, a wide channel of the outer membrane of E. coli, by studying the effect of salts of divalent cations on the transport properties of the channel. The regulation of divalent cations concentration is essential in cell metabolism and understanding their effects is of key importance, not only in the channels specifically designed to control their passage but also in other multiionic channels. In particular, in porin channels like OmpF, divalent cations modulate the efficiency of molecules having antimicrobial activity. Taking advantage of the fact that the OmpF channel atomic structure has been resolved both in water and in MgCl2 aqueous solutions, we analyze the single channel conductance and the channel selectivity inversion aiming to separate the role of the electrolyte itself, and the counterion accumulation induced by the protein channel charges and other factors (binding, steric effects, etc. that being of minor importance in salts of monovalent cations become crucial in the case of divalent cations.

  3. Preparation, investigation of metal ion removal and flocculation performances of grafted hydroxyethyl starch.

    Kolya, Haradhan; Tripathy, Tridib


    Ceric ion induced graft copolymerization of N,N-dimethyl acrylamide (DMA) and acryl amide (AM) were carried out onto the hydroxyethyl starch (HES). These grafted copolymers were used for the removal of metal ions from their aqueous solutions. Flocculation performances of the synthesized graft copolymers were evaluated in 1.0 wt% silica suspensions. A comparative study of the flocculation performances of the synthetic graft copolymers was also made. The different factors affecting metal ion absorption, namely pH, treatment time, temperature and polymer dose were studied. A comparative study of the metal ion removal capacity of the two synthetic graft copolymers was also made in five metal ions namely Ni(II), Zn(II), Cu(II), Pb(II) and Hg(II). The metal ion removal capacity follows the order Hg(II)>Cu(II)>Zn(II)>Ni(II)>Pb(II) in both the two synthetic polymers. Between the two graft copolymers, graft copolymer based on AM shows better performance than that based on DMA in all the metal solutions. But the flocculation performance of DMA based graft copolymer showed better performances than that AM based graft copolymer. The former also performed best when compared to the commercial flocculants in the same suspension.

  4. Metal ion release from silver soldering and laser welding caused by different types of mouthwash.

    Erdogan, Ayse Tuygun; Nalbantgil, Didem; Ulkur, Feyza; Sahin, Fikrettin


    To compare metal ion release from samples welded with silver soldering and laser welding when immersed into mouthwashes with different ingredients. A total of 72 samples were prepared: 36 laser welded and 36 silver soldered. Four samples were chosen from each subgroup to study the morphologic changes on their surfaces via scanning electron microscopy (SEM). Each group was further divided into four groups where the samples were submerged into mouthwash containing sodium fluoride (NaF), mouthwash containing sodium fluoride + alcohol (NaF + alcohol), mouthwash containing chlorhexidine (CHX), or artificial saliva (AS) for 24 hours and removed thereafter. Subsequently, the metal ion release from the samples was measured with inductively coupled plasma mass spectrometry (ICP-MS). The metal ion release among the solutions and the welding methods were compared. The Kruskal-Wallis and analysis of variance (ANOVA) tests were used for the group comparisons, and post hoc Dunn multiple comparison test was utilized for the two group comparisons. The level of metal ion release from samples of silver soldering was higher than from samples of laser welding. Furthermore, greater amounts of nickel, chrome, and iron were released from silver soldering. With regard to the mouthwash solutions, the lowest amounts of metal ions were released in CHX, and the highest amounts of metal ions were released in NaF + alcohol. SEM images were in accord with these findings. The laser welding should be preferred over silver soldering. CHX can be recommended for patients who have welded appliances for orthodontic reasons.

  5. Improving Passivation Process of Si Nanocrystals Embedded in SiO2 Using Metal Ion Implantation

    Jhovani Bornacelli


    Full Text Available We studied the photoluminescence (PL of Si nanocrystals (Si-NCs embedded in SiO2 obtained by ion implantation at MeV energy. The Si-NCs are formed at high depth (1-2 μm inside the SiO2 achieving a robust and better protected system. After metal ion implantation (Ag or Au, and a subsequent thermal annealing at 600°C under hydrogen-containing atmosphere, the PL signal exhibits a noticeable increase. The ion metal implantation was done at energies such that its distribution inside the silica does not overlap with the previously implanted Si ion . Under proper annealing Ag or Au nanoparticles (NPs could be nucleated, and the PL signal from Si-NCs could increase due to plasmonic interactions. However, the ion-metal-implantation-induced damage can enhance the amount of hydrogen, or nitrogen, that diffuses into the SiO2 matrix. As a result, the surface defects on Si-NCs can be better passivated, and consequently, the PL of the system is intensified. We have selected different atmospheres (air, H2/N2 and Ar to study the relevance of these annealing gases on the final PL from Si-NCs after metal ion implantation. Studies of PL and time-resolved PL indicate that passivation process of surface defects on Si-NCs is more effective when it is assisted by ion metal implantation.

  6. Production of multicharged metal ion beams on the first stage of tandem-type ECRIS

    Hagino, Shogo, E-mail:; Nagaya, Tomoki; Nishiokada, Takuya; Otsuka, Takuro; Sato, Fuminobu; Kato, Yushi [Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita-shi, Osaka 565-0871 (Japan); Muramatsu, Masayuki; Kitagawa, Atsushi [National Institute of Radiological Sciences (NIRS), 4-9-1, Anagawa, Inage-ku, Chiba-shi, Chiba 263-8555 (Japan)


    Multicharged metal ion beams are required to be applied in a wide range of fields. We aim at synthesizing iron-endohedral fullerene by transporting iron ion beams from the first stage into the fullerene plasma in the second stage of the tandem-type electron cyclotron resonance ion source (ECRIS). We developed new evaporators by using a direct ohmic heating method and a radiation heating method from solid state pure metal materials. We investigate their properties in the test chamber and produce iron ions on the first stage of the tandem-type ECRIS. As a result, we were successful in extracting Fe{sup +} ion beams from the first stage and introducing Fe{sup +} ion beams to the second stage. We will try synthesizing iron-endohedral fullerene on the tandem-type ECRIS by using these evaporators.

  7. Extraction of alginate biopolymer present in marine alga sargassum filipendula and bioadsorption of metallic ions

    Sirlei Jaiana Kleinübing


    Full Text Available This paper studies the bioadsorption of Pb2+, Cu2+, Cd2+ and Zn2+ ions by marine alga Sargassum filipendula and by the alginate biopolymer extracted from this alga. The objective is to evaluate the importance of this biopolymer in removing different metallic ions by the marine alga S. filipendula. In the equilibrium study, the same affinity order was observed for both bioadsorbents: Pb2+ > Cu2+ > Zn2+ > Cd2+. For Pb2+ and Cu2+ ions when the alginate is isolated and acting as bioadsorbents, adsorption capacities greater than those found for the alga were observed, indicating that it is the main component responsible for the removal of metallic ions. For Zn2+ and Cd2+ ions, greater bioadsorption capacities were observed for the alga, indicating that other functional groups of the alga, such as sulfates and amino, are also important in the bioadsorption of these ions.

  8. Mitigation of Metal Ion Pollution from Industrial Waste Water Using Waste Wool

    Prajapat, Garima; Purohit, Praveen

    A study on the adsorption of copper (II) ions from the aqueous solution on waste wool had been carried out to analyze the adsorption capacity of waste wool, thereby aiming towards mitigation of metal ion pollution in industrial waste water. The effect of varying concentration of copper ions and varying time period, was studied on fixed weight of waste wool. The initial and final concentration of copper ions was measured by conductometric and spectrophotometric methods. Adsorption data were modeled with the langmuir and freundlich adsorption isotherms. The isotherm and first order equation were found to be applicable. Removal of metal ions using industrial waste wool is found to be favourable. Thus the work can be extended to study various physico-chemical parameters for removal of copper (II) ions from industrial effluents using waste wool. A later work can be involved where the waste wool adsorption parameter can be further utilized for composite ceramic products.

  9. Heavy ion time-of-flight ERDA of high dose metal implanted germanium

    Dytlewski, N.; Evans, P.J.; Noorman, J.T. [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia); Wielunski, L.S. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), Lindfield, NSW (Australia). Div. of Applied Physics; Bunder, J. [New South Wales Univ., Wollongong, NSW (Australia). Wollongong Univ. Coll


    With the thick Ge substrates used in ion implantation, RBS can have difficulty in resolving the mass-depth ambiguities when analysing materials composed of mixtures of elements with nearly equal masses. Additional, and complimentary techniques are thus required. This paper reports the use of heavy ion time-of-flight elastic recoil detection analysis (ToF- ERDA), and conventional RBS in the analysis of Ge(100) implanted with high dose Ti and Cu ions from a MEWA ion source . Heavy ion ToF ERDA has been used to resolve, and profile the implanted transition metal species, and also to study any oxygen incorporation into the sample resulting from the implantation, or subsequential reactions with air or moisture. This work is part of a study on high dose metal ion implantation of medium atomic weight semiconductor materials. 13 refs., 6 figs.

  10. Production of multicharged metal ion beams on the first stage of tandem-type ECRIS

    Hagino, Shogo; Nagaya, Tomoki; Nishiokada, Takuya; Otsuka, Takuro; Muramatsu, Masayuki; Kitagawa, Atsushi; Sato, Fuminobu; Kato, Yushi


    Multicharged metal ion beams are required to be applied in a wide range of fields. We aim at synthesizing iron-endohedral fullerene by transporting iron ion beams from the first stage into the fullerene plasma in the second stage of the tandem-type electron cyclotron resonance ion source (ECRIS). We developed new evaporators by using a direct ohmic heating method and a radiation heating method from solid state pure metal materials. We investigate their properties in the test chamber and produce iron ions on the first stage of the tandem-type ECRIS. As a result, we were successful in extracting Fe+ ion beams from the first stage and introducing Fe+ ion beams to the second stage. We will try synthesizing iron-endohedral fullerene on the tandem-type ECRIS by using these evaporators.

  11. Metal ions affecting the pulmonary and cardiovascular systems.

    Corradi, Massimo; Mutti, Antonio


    Some metals, such as copper and manganese, are essential to life and play irreplaceable roles in, e.g., the functioning of important enzyme systems. Other metals are xenobiotics, i.e., they have no useful role in human physiology and, even worse, as in the case of lead, may be toxic even at trace levels of exposure. Even those metals that are essential, however, have the potential to turn harmful at very high levels of exposure, a reflection of a very basic tenet of toxicology--"the dose makes the poison." Toxic metal exposure may lead to serious risks to human health. As a result of the extensive use of toxic metals and their compounds in industry and consumer products, these agents have been widely disseminated in the environment. Because metals are not biodegradable, they can persist in the environment and produce a variety of adverse effects. Exposure to metals can lead to damage in a variety of organ systems and, in some cases, metals also have the potential to be carcinogenic. Even though the importance of metals as environmental health hazards is now widely appreciated, the specific mechanisms by which metals produce their adverse effects have yet to be fully elucidated. The unifying factor in determining toxicity and carcinogenicity for most metals is the generation of reactive oxygen and nitrogen species. Metal-mediated formation of free radicals causes various modifications to nucleic acids, enhanced lipid peroxidation, and altered calcium and sulfhydryl homeostasis. Whilst copper, chromium, and cobalt undergo redox-cycling reactions, for metals such as cadmium and nickel the primary route for their toxicity is depletion of glutathione and bonding to sulfhydryl groups of proteins. This chapter attempts to show that the toxic effects of different metallic compounds may be manifested in the pulmonary and cardiovascular systems. The knowledge of health effects due to metal exposure is necessary for practising physicians, and should be assessed by inquiring

  12. The use of ion flotation for detoxification of metal-contaminated waters and process effluents

    Doyle, F.M.; Duyvesteyn, S.; Sreenivasarao, K. [Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering


    Toxic metals entering surface or ground water from sources such as metal finishing shop spills and abandoned mines can pose a significant threat to public health and the environment. Ion flotation and similar foam separation techniques show great promise for treating dilute, metal-contaminated solutions, and could also be used to treat effluents from many minerals and metallurgical processing operations prior to discharge. In ion flotation, an appropriate collector is added to the solution to form hydrophobic complexes with the metal ions. These metal-bearing species are then removed by flotation, usually with trace addition of a frother to stabilize the foam. In an effort to better understand the underlying scientific and engineering principles that determine the performance of ion flotation, the removal of Cu(II), Pb(II), Cd(II), Cr(III) and Cr(VI) has been studied using laboratory scale flotation columns in batch mode. The effects of the superficial air velocity, solution and froth height, nature of the collector, collector:metal-ion ratio, ionic strength and several frothers at low concentrations on the flotation kinetics are reported. Finally, results are presented on methods that might allow regeneration of collector and recovery of by-product metal from the foam product.

  13. Interactions of atrazine with transition metal ions in aqueous media: experimental and computational approach.

    Kumar, Vijay; Kumar, Virender; Upadhyay, Niraj; Sharma, Sitansh


    Transition metal ions have their own significances and utility. Externally applied pesticides may alter the bioavailability of these metal ions to plants through the coordinating ability of these pesticides with metal ions. In current study a series of metal complexes containing atrazine (Atr) group(s) attached to metal(II) (M) frame, with the formula; [M(Atr)n.xH2O.yCl] (where M = Mn, Fe, Co, Ni, Cu or Zn; n = 1 or 2; x = 1-4; y = 1-2), have been synthesized for the first time to check the interactions of atrazine with transition metal ions. More importantly, all the complexes were synthesized at neutral pH in aqueous medium. The major differences among the FTIR spectra were observed between 3,700-2,800 and 1,800-1,350 cm(-1). On the basis of FTIR, CHN and computational study, it was observed that Mn, Ni and Cu formed complexes in 1:2 and Fe, Co and Zn in 1:1. The obtained results were supported by 3D molecular modeling using GAMESS computations as a package of ChemBio3D Ultra14 program. The FTIR spectral analysis and 3D molecular modeling suggests that the Atr can show coordination through the nitrogen (in between two side chains) of ring as well as nitrogen (non steric amine) of side chain with different metal ions.

  14. GaBi alloy liquid metal ion source for microelectronics research.

    Bischoff, L; Pilz, W; Ganetsos, Th; Forbes, R G; Akhmadaliev, Ch


    A GaBi alloy liquid metal ion source has been studied. From an analysis of the source mass spectra as a function of emission current, a mechanism is suggested for the production of single- and double-charged ions. There is good agreement with the results of Swanson's investigations of a pure Bi source.

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

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


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

  16. Metal ion induced FRET OFF-ON in tren/dansyl-appended rhodamine.

    Lee, Min Hee; Kim, Hyun Jung; Yoon, Sangwoon; Park, Noejung; Kim, Jong Seung


    A series of new fluorescent probes bearing tren-spaced rhodamine B and dansyl groups have been synthesized. Compound 1 exhibits selective changes in the absorption and the emission spectra toward Cu2+ ion over miscellaneous metal cations. Among 1-3, 1 shows the best FRET efficiency through dansyl emission to rhodamine absorption for the Cu2+ ion.

  17. Metal Cation Binding to Gas-Phase Pentaalanine: Divalent Ions Restructure the Complex

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


    Ion-neutral complexes of pentaalalanine with several singly- and doubly charged metal ions are examined using conformation analysis by infrared multiple photon dissociation (IRMPD) spectroscopy and density functional theory (DFT) computations. The infrared spectroscopy in the 1500-1800 cm(-1) region

  18. Metal Cation Binding to Gas-Phase Pentaalanine: Divalent Ions Restructure the Complex

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


    Ion-neutral complexes of pentaalalanine with several singly- and doubly charged metal ions are examined using conformation analysis by infrared multiple photon dissociation (IRMPD) spectroscopy and density functional theory (DFT) computations. The infrared spectroscopy in the 1500-1800 cm(-1) region

  19. The Characteristics Of The Direct Metal Ion Beam Source And Its Applications (indium Tin Oxide)

    Kim, D


    It is well known that thin film properties depends on its microstructures and the surface mobility is most important parameters to consider microstructures and to obtain high quality thin films. Thus, currently ion beam based deposition which can control surface mobility with kinetic energy of auxiliary gas ion investigated intensively. Recently we developed the DMIBD system which can control ion beam energy precisely under 500Ev and also ion beam flux, independently. In this work, the optimum process parameters of DMIBD such as secondary ion yields, ion/atom arrival ratios, ion energy spread, and deposition rates for various metal targets were measured as functions of Cs+ ion bombarding energy, Cs+ ion dose, and secondary ion beam energy, respectively. From the results, the secondary ion yields for C,Al,Si,Cu,Ta, and W were about 20% and the ion energy spread also less than 10% regardless of the ion beam energy. In order to investigated the effect of secondary ion beam energy on the thin film properties such...

  20. Property enchancement of polyimide films by way of the incorporation of lanthanide metal ions

    Thompson, David W.


    Lanthanide metal ions were incorporated into the polyimide derived from 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and 1,3-bis(aminophenoxy) benzene (APB) in an attempt to produce molecular level metal-polymer composites. The lanthanide series of metal ions (including aluminum, scandium, and yttrium) provide discrete and stable metal ions in the 3+ oxidation state. Throughout the series there is a uniform variation in ionic size ranging from 50 pm for aluminum to a maximum of 103.4 pm for cerium and gradually decreasing again to 84.8 pm for lutetium. The high charge-to-size ratio for these ions as well as the ability to obtain large coordination numbers makes them excellent candidates for interacting with the polymer substructure. The distinct lack of solubility of simple lanthanide salts such as the acetates and halides has made it difficult to obtain metal ions distributed in the polymer framework as discrete ions or metal complexes rather than microcomposites of metal clusters. (Lanthanum nitrates are quite soluble, but the presence of the strongly oxidizing nitrate ion leads to serious degradation of the polymer upon thermal curing. This work was successful at extending the range of soluble metals salts by using chelating agents derived from the beta-diketones dipivaloylmethane, dibenzoylmethane, trifluoroacetylacetone, and hexafluoroacetylacetone. Metal acetates which are insoluble in dimethylacetamide dissolve readily in the presence of the diketones. Addition of the polyimide yields a homogeneous resin which is then cast into a clear film. Upon curing clear films were obtained with the dibenzoylmethane and trifluoroacetylacetone ligands. The dipavaloylmethane precipitates the metal during the film casting process, and hexafluoroacetylacetone gives cured films which are deformed and brittle. These clear films are being evaluated for the effect of the metal ions on the coefficient of thermal expansion, resistance to atomic oxygen, and on

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

    Lindgård, Per-Anker


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

  2. Effects of complexing compounds on sorption of metal ions to cement

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


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

  3. Removal of toxic heavy metal ions in runoffs by modified alfalfa and juniper

    J.S. Han; J.K. Park; S.H. Min


    A series of batch isotherm tests was performed with alfalfa and juniper fibers to evaluate the effectiveness in filtering toxic heavy metals from stormwater. The adsorption of the heavy metal ions on the alfalfa and juniper fibers was strongly dependent on the equilibrium pH value of the solution. The change in sorption rate over time showed that two different sorption...

  4. Effect of surface modification of microfiltration membrane on capture of toxic heavy metal ions.

    Madaeni, Sayed Siavash; Heidary, Farhad


    A novel complexing membrane containing 8-hydroxyquinoline groups was used for the removal of heavy metal ions (Cd2+ and Ni2+) from aqueous solution. The functionalized membranes were characterized by FTIR-ATR, SEM and EDAX for the presence of functional groups, the physical structure of the membranes and the analysis of the particles deposited on the membrane, respectively. The influence of 8-hydroxyquinoline concentration, feed concentration, pH and temperature of the solution on capture capability was studied. The modified membrane showed a higher affinity to Cd2+ cations than to Ni2+. The metal ion rejection was increased with an increase in concentration of 8-hydroxyquinoline from 0.5 to 2.0 wt%. However at a ligand concentration higher than 2.0 wt%, no significant change was observed in the metal rejection. The experimental results revealed that the metal rejection was decreased with an increase in metal ion concentration in the feed. Moreover the rejection depended on feed pH and is higher for elevated pH. By changing the temperature in the range of 23-28 degrees C, no considerable effect on metal rejection was observed. However, a higher temperature resulted in a decline in metal rejection. For filtration of a mixture of the two metal ions, the retention was similar to that of the single cations, i.e. Cd > Ni but with smaller absolute rejections.

  5. Interactions between metal ions and biogeo-surfaces in soil and water

    Weng, L.


    To provide the basis for an improved quantitative risk assessment of heavy metals in the environment, the interactions between the metal ions and the biogeo-surfaces in soil and water were studied using both experimental and modelling approaches.The Donnan membrane technique was developed and optimi

  6. A QICAR Model for Metal Ion Toxicity Established via PLS Method

    LI Yu; JIANG Long; LI Xiao-li; HU Yan; WEN Jing-ya


    The partial least squares(PLS) method was employed to establish a quantitative ion characteristics-activity relationship(QICAR) model for metal ion toxicity(EC50 of 15 metal ions).The ion characteristics included AN(the atomic number),AIP(the change in ionization potential,eV),Xm(the electronegativity,eV),AW(the atomic weight),Xm2r(the covalent index),△E0(the absolute difference between electrochemical potential of the ion and that of its first stable reduced state,eV),│lgKoH│(the absolute value of the lg of the first hydrolysis constant),AR(the atomic radius,nm),AR/AW(the ratio between atomic radius and atomic weight) and σp(the softness index) selected based on relative correlation analysis.The simulated and tested(with the other four metals) efficiency coefficients of the model are 0.88 and 0.96,respectively.The information revealed from the QICAR model indicates that the value of the metal ion toxicity was positively correlated with variables AN,△IP,Xm,AW and Xm2r; negatively correlated with variables △E0,│lgKoH│,AR/AW,AR and σp,and ion characteristics AE0,Xm,σp and Xm2r were found to contribute more to the toxicity of metal ions via the accurate analysis method provided by PLS.The model could be used to predict the toxicity of the target metals and preliminary to assess combined pollution and environmental risk for heavy metals in the environments.

  7. Electrochemical membrane reactor: In situ separation and recovery of chromic acid and metal ions

    Khan, Jeeshan; Tripathi, Bijay P.; Saxena, Arunima; Shahi, Vinod K. [Electro-Membrane Processes Division, Central Salt and Marine Chemicals Research Institute, Bhavnagar 364002, Gujarat (India)


    An electrochemical membrane reactor with three compartments (anolyte, catholyte and central compartment) based on in-house-prepared cation- and anion-exchange membrane was developed to achieve in situ separation and recovery of chromic acid and metal ions. The physicochemical and electrochemical properties of the ion-exchange membrane under standard operating conditions reveal its suitability for the proposed reactor. Experiments using synthetic solutions of chromate and dichromate of different concentrations were carried out to study the feasibility of the process. Electrochemical reactions occurring at the cathode and anode under operating conditions are proposed. It was observed that metal ion migrated through the cation-exchange membrane from central compartment to catholyte and OH{sup -} formation at the cathode leads to the formation of metal hydroxide. Simultaneously, chromate ion migrated through the anion-exchange membrane from central compartment to the anolyte and formed chromic acid by combining H{sup +} produced their by oxidative water splitting. Thus a continuous decay in the concentration of chromate and metal ion was observed in the central compartment, which was recovered separately in the anolyte and catholyte, respectively, from their mixed solution. This process was completely optimized in terms of operating conditions such as initial concentration of chromate and metal ions in the central compartment, the applied cell voltage, chromate and metal ion flux, recovery percentage, energy consumption, and current efficiency. It was concluded that chromic acid and metal ions can be recovered efficiently from their mixed solution leaving behind the uncharged organics and can be reused as their corresponding acid and base apart from the purifying water for further applications. (author)

  8. 18-Electron rule inspired Zintl-like ions composed of all transition metals.

    Zhou, Jian; Giri, Santanab; Jena, Purusottam


    Zintl phase compounds constitute a unique class of compounds composed of metal cations and covalently bonded multiply charged cluster anions. Potential applications of these materials in solution chemistry and thermoelectric materials have given rise to renewed interest in the search for new Zintl ions. Up to now these ions have been mostly composed of group 13, 14, and 15 post-transition metal elements and no Zintl ions composed of all transition metal elements are known. Using gradient corrected density functional theory we show that the 18-electron rule can be applied to design a new class of Zintl-like ions composed of all transition metal atoms. We demonstrate this possibility by using Ti@Au12(2-) and Ni@Au6(2-) di-anions as examples of Zintl-like ions. Predictive capability of our approach is demonstrated by showing that FeH6(4-) in an already synthesized complex metal hydride, Mg2FeH6, is a Zintl-like ion, satisfying the 18-electron rule. We also show that novel Zintl phase compounds can be formed by using all transition metal Zintl-like ions as building blocks. For example, a two-dimensional periodic structure of Na2[Ti@Au12] is semiconducting and nonmagnetic while a one-dimensional periodic structure of Mg[Ti@Au12] is metallic and ferromagnetic. Our results open the door to the design and synthesis of a new class of Zintl-like ions and compounds with potential for applications.

  9. Engineering Short Preorganized Peptide Sequences for Metal Ion Coordination: Copper(II) a Case Study.

    Lima, L M P; Iranzo, O


    Peptides are multidentate chiral ligands capable of coordinating different metal ions. Nowadays, they can be obtained with high yield and purity, thanks to the advances on peptide/protein chemistry as well as in equipment (peptide synthesizers). Based on the identity and length of their amino acid sequences, peptides can present different degrees of flexibility and folding. Although short peptide sequences (ion coordination. Based on our experience, we present a general scheme for the design, synthesis, and characterization of these peptidic scaffolds and provide protocols for the study of their metal ion coordination properties.


    HUANGWenqiang; HANLijun; 等


    Metal ion-imprintedly crosslinked chitosan resin 1 and resin 2 were prepared by the use of Cu2+ and Ni2+ as template ions and glutaraldehyde as crosslinking agent,respectively,Through investigation on the adsorption capacties and binding constants for Cu2+,Ni2+ and Co2+ ions on chitosan resins,resin 1 and resin 2 exhibit the adsorption selectivity for the mixture solution of 1L1 Cu2+ and Ni2+ ions.The adsorption selectivity of metal ion-imprinted resins for their template ions in much higher than that of uncrosslinked chitosan resin.

  11. Advantages and Uses of AMTEC

    Lodhi, M. A. K.


    Static conversion systems are gaining importance in recent times because of newer applications of electricity like in spacecraft, hybrid-electric vehicles, military uses and domestic purposes. Of the many new static energy conversion systems that are being considered, one is the Alkali Metal Thermal Electric Converter (AMTEC). It is a thermally regenerative, electrochemical device for the direct conversion of heat to electrical power. As the name suggests, this system uses an alkali metal in its process. The electrochemical process involved in the working of AMTEC is ionization of alkali metal atoms at the interface of electrode and electrolyte. The electrons produced as a result flow through the external load thus doing work, and finally recombine with the metal ions at the cathode. AMTECs convert the work done during the nearly isothermal expansion of metal vapor to produce a high current and low voltage electron flow. Due to its principle of working it has many inherent advantages over other conventional generators. These will be discussed briefly.

  12. Removal of Heavy Metal Ions from Polluted Waters by Using of Low Cost Adsorbents: Review

    M. Ghaedi


    Full Text Available Adsorption is a fundamental process in the physicochemical treatment of wastewaters which industries employ to reduce hazardous organic and inorganic wastes in effluents. In recent years the use of low-cost adsorbents has been widely investigated as a replacement for the currently costly methods of removing heavy metal ions from wastewater. It is well-known that cellulosic waste materials can be obtained and employed as cheap adsorbents and their performance to remove heavy metal ions can be affected upon chemical treatment. In this study, the use of some of low cost adsorbents for the removal of heavy metals from wastewater has been reviewed.

  13. Lability of heavy metal species in aquatic humic substances characterized by ion exchange with cellulose phosphate.

    Rocha, J C; Toscano, I A; Burba, P


    Labile metal species in aquatic humic substances (HSs) were characterized by ion exchange on cellulose phosphate (CellPhos) by applying an optimized batch procedure. The HSs investigated were pre-extracted from humic-rich waters by ultrafiltration and a resin XAD 8 procedure. The HS-metal species studied were formed by complexation with Cd(II), Ni(II), Cu(II), Mn(II) and Pb(II) as a function of time and the ratio ions to HSs. The kinetics and reaction order of this exchange process were studied. At the beginning ( Pb > Mn > Ni > Cd. The required metal determinations were carried out by atomic absorption spectrometry.

  14. Synthesis, Characterization and Metal Ion Detection of Novel Fluoroionophores Based on Heterocyclic Substituted Alanines

    M. Manuela M Raposo


    Full Text Available The synthesis of new fluorescent probes containing the thiophene andbenzoxazole moieties combined with an alanine residue is described. The resulting highlyfluorescent heterocyclic alanine derivatives respond via a quenching effect, withparamagnetic Cu(II and Ni(II metal ions and with diamagnetic Hg(II, as shown by theabsorption and steady-state fluorescence spectroscopy studies. The formation ofmononuclear or dinuclear metal complexes was postulated based on the presence of thefree carboxylic acid as binding site and also with the interaction with the donor atoms inthe chromophore. Interaction with other important biological metal ions such as Zn(II,Ca(II and Na(I was also explored.

  15. Sub-millimeter Spectroscopy of Astrophysically Important Molecules and Ions: Metal Hydrides, Halides, and Cyanides

    Ziurys, L. M.; Flory, M. A.; Halfen, D. T.


    With the advent of SOFIA, Herschel, and SAFIR, new wavelength regions will become routinely accessible for astronomical spectroscopy, particularly at submm frequencies (0.5-1.1 THz). Molecular emission dominates the spectra of dense interstellar gas at these wavelengths. Because heterodyne detectors are major instruments of these missions, accurate knowledge of transition frequencies is crucial for their success. The Ziurys spectroscopy laboratory has been focusing on the measurement of the pure rotational transitions of astrophysically important molecules in the sub-mm regime. Of particular interest have been metal hydride species and their ions, as well as metal halides and cyanides. A new avenue of study has included metal bearing molecular ions.

  16. Removal of heavy metal ions from aqueous solutions using clinoptilolite

    Golomeova, Mirjana; Zendelska, Afrodita; Krstev, Boris; Golomeov, Blagoj; Krstev, Aleksandar


    Heavy metals are a common pollutant found in various industrial effluents. They are often encountered in mining operations and acid mine drainage. The heavy metals are highly toxic and are non-biodegradable, therefore they must be removed from the polluted streams in order to meet increasingly stringent environmental quality standards. Removal of heavy metals can be accomplished by a variety of techniques. Conventional methods typically involve the use of processes such as coag...

  17. Removal of heavy metal ions from aqueous solutions using clinoptilolite

    Golomeova, Mirjana; Zendelska, Afrodita; Krstev, Boris; Golomeov, Blagoj; Krstev, Aleksandar


    Heavy metals are a common pollutant found in various industrial effluents. They are often encountered in mining operations and acid mine drainage. The heavy metals are highly toxic and are non-biodegradable, therefore they must be removed from the polluted streams in order to meet increasingly stringent environmental quality standards. Removal of heavy metals can be accomplished by a variety of techniques. Conventional methods typically involve the use of processes such as coag...

  18. Heavy metal ions in wines: meta-analysis of target hazard quotients reveal health risks

    Petróczi Andrea


    Full Text Available Abstract Background Metal ions such as iron and copper are among the key nutrients that must be provided by dietary sources. Numerous foodstuffs have been evaluated for their contributions to the recommended daily allowance both to guide for satisfactory intake and also to prevent over exposure. In the case of heavy metal ions, the focus is often on exposure to potentially toxic levels of ions such as lead and mercury. The aim of this study is to determine target hazard quotients (THQ from literature reports giving empirical levels of metal ions in table wines using the reference upper safe limit value. Contributions to the THQ value were calculated for seven metal ions along with total values for each wine. Results The THQ values were determined as ranges from previously reported ranges of metal ion concentrations and were frequently concerningly high. Apart from the wines selected from Italy, Brazil and Argentina, all other wines exhibited THQ values significantly greater than one indicating levels of risk. The levels of vanadium, copper and manganese had the highest impact on THQ measures. Typical potential maximum THQ values ranged from 50 to 200 with Hungarian and Slovakian wines reaching 300. THQ values for a sample of red and white wines were high for both having values ranging from 30 to 80 for females based on a 250 mL glass per day. Conclusion The THQ values calculated are concerning in that they are mainly above the safe level of THQ

  19. Interface-modulated approach toward multilevel metal oxide nanotubes for lithium-ion batteries and oxygen reduction reaction

    Jiashen Meng; Chaojiang Niu; Xiong Liu; Ziang Liu; Hongliang Chen; Xuanpeng Wang; Jiantao Li


    Metal oxide hollow structures with multilevel interiors are of great interest for potential applications such as catalysis,chemical sensing,drug delivery,and energy storage.However,the controlled synthesis of multilevel nanotubes remains a great challenge.Here we develop a facile interface-modulated approach toward the synthesis of complex metal oxide multilevel nanotubes with tunable interior structures through electrospinning followed by controlled heat treatment.This versatile strategy can be effectively applied to fabricate wire-in-tube and tubein-tube nanotubes of various metal oxides.These multilevel nanotubes possess a large specific surface area,fast mass transport,good strain accommodation,and high packing density,which are advantageous for lithium-ion batteries (LIBs)and the oxygen reduction reaction (ORR).Specifically,shrinkable CoMn2O4 tube-in-tube nanotubes as a lithium-ion battery anode deliver a high discharge capacity of ~565 mAh.g-1 at a high rate of 2 A.g-1,maintaining 89% of the latter after 500 cycles.Further,as an oxygen reduction reaction catalyst,these nanotubes also exhibit excellent stability with about 92% current retention after 30,000 s,which is higher than that of commercial Pt/C (81%).Therefore,this feasible method may push the rapid development of one-dimensional (1D) nanomaterials.These multifunctional nanotubes have great potential in many frontier fields.

  20. Ultrahigh-current-density metal-ion implantation and diamondlike-hydrocarbon films for tribological applications

    Wilbur, P. J.


    The metal-ion-implantation system used to implant metals into substrates are described. The metal vapor required for operation is supplied by drawing sufficient electron current from the plasma discharge to an anode-potential crucible so a solid, pure metal placed in the crucible will be heated to the point of vaporization. The ion-producing, plasma discharge is initiated within a graphite-ion-source body, which operates at high temperature, by using an argon flow that is turned off once the metal vapor is present. Extraction of ion beams several cm in diameter at current densities ranging to several hundred micro-A/sq cm on a target 50 cm downstream of the ion source were demonstrated using Mg, Ag, Cr, Cu, Si, Ti, V, B, and Zr. These metals were implanted into over 100 substrates (discs, pins, flats, wires). A model describing thermal stresses induced in materials (e.g. ceramic plates) during high-current-density implantation is presented. Tribological and microstructural characteristics of iron and 304-stainless-steel samples implanted with Ti or B are examined. Diamondlike-hydrocarbon coatings were applied to steel surfaces and found to exhibit good tribological performance.

  1. Structure simulation into a lamellar supramolecular network and calculation of the metal ions/ligands ratio

    Visa Aurelia


    Full Text Available Abstract Background Research interest in phosphonates metal organic frameworks (MOF has increased extremely in the last two decades, because of theirs fascinating and complex topology and structural flexibility. In this paper we present a mathematical model for ligand/metal ion ratio of an octahedral (Oh network of cobalt vinylphosphonate (Co(vP·H2O. Results A recurrent relationship of the ratio between the number of ligands and the number of metal ions in a lamellar octahedral (Oh network Co(vP·H2O, has been deducted by building the 3D network step by step using HyperChem 7.52 package. The mathematical relationship has been validated using X ray analysis, experimental thermogravimetric and elemental analysis data. Conclusions Based on deducted recurrence relationship, we can conclude prior to perform X ray analysis, that in the case of a thermogravimetric analysis pointing a ratio between the number of metal ions and ligands number around 1, the 3D network will have a central metal ion that corresponds to a single ligand. This relation is valid for every type of supramolecular network with divalent metal central ion Oh coordinated and bring valuable information with low effort and cost.

  2. Adaptation of intertidal biofilm communities is driven by metal ion and oxidative stresses

    Zhang, Weipeng


    Marine organisms in intertidal zones are subjected to periodical fluctuations and wave activities. To understand how microbes in intertidal biofilms adapt to the stresses, the microbial metagenomes of biofilms from intertidal and subtidal zones were compared. The genes responsible for resistance to metal ion and oxidative stresses were enriched in both 6-day and 12-day intertidal biofilms, including genes associated with secondary metabolism, inorganic ion transport and metabolism, signal transduction and extracellular polymeric substance metabolism. In addition, these genes were more enriched in 12-day than 6-day intertidal biofilms. We hypothesize that a complex signaling network is used for stress tolerance and propose a model illustrating the relationships between these functions and environmental metal ion concentrations and oxidative stresses. These findings show that bacteria use diverse mechanisms to adapt to intertidal zones and indicate that the community structures of intertidal biofilms are modulated by metal ion and oxidative stresses.

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

    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


    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.

  4. Adsorption of Heavy Metal Ions by Adsorbent from Waste Mycelium Chitin

    苏海佳; 王丽娟; 等


    The adsorption properties of chitin adsorbent from mycelium of fermentation industries for the removal of heavy metal ions were studied.The result shows that the chitin adsorbent has high adsorption capacity for many heavy metal ions and Ni2+ in citric acid.The influence of pH was significant:When pH is higher than 4.0,the high adsorption capacity is obtained.otherwise H+ ion inhibits the adsorption of heavy metal ions.The comparison of the chitin adsorbent with some other commercial adsorbents was made,in which that the adsorption behavior of chitin adsorbent is close to that of commercial cation exchange adsorbents,and its cost is much lower than those commercial adsorbents.

  5. Removal of heavy metal ions by biogenic hydroxyapatite: Morphology influence and mechanism study

    Wang, Dandan; Guan, Xiaomei; Huang, Fangzhi; Li, Shikuo; Shen, Yuhua; Chen, Jun; Long, Haibo


    Based on the synthesis of hydroxyapatite (HA) with different morphologies, such as nanorod-like, flower-like and sphere-like assembled HA nanorods, a new strategy has been developed for the removal of heavy metal ions such as Pb2+, Cu2+, Mn2+, Zn2+. The dependence of removal efficiency on the morphology and the suspended concentration of trapping agent, the removal time and selectivity were evaluated and discussed. The experimental results proved that the removal capacity of flower-like assembled HA nanorods (NAFL-HA) was the best, and the maximum removal ratio for Pb2+ ion was 99.97%. The mechanism of Pb2+ removal was studied in detail, noting that some metal ions were completely incorporated into hydroxyapatitie to produce Pb-HA. It reveals that the metal ions capture by HA is mainly controlled by sample surface adsorption and co-precipitation, which are directly controlled by sample morphology.

  6. Absolute advantage

    J.G.M. van Marrewijk (Charles)


    textabstractA country is said to have an absolute advantage over another country in the production of a good or service if it can produce that good or service using fewer real resources. Equivalently, using the same inputs, the country can produce more output. The concept of absolute advantage can a

  7. Metal ion interpretation in resurfacing versus conventional hip arthroplasty and in whole blood versus serum. How should we interpret metal ion data.

    Smolders, José M H; Bisseling, Pepijn; Hol, Annemiek; Van Der Straeten, Catherine; Schreurs, B Willem; van Susante, Job L C


    Metal ions generated from joint replacements are a cause for concern. There is no consensus on the best surrogate measure of metal ion exposure, and both serum and whole blood measurements are used in clinical practice. This study provides a guideline for interpretation of metal ion analysis in clinical practice. In a prospective trial comparing hip resurfacing (HR) with a conventional metal-on-metal (MoM) total hip arthroplasty (THA) cobalt and chromium levels were determined for whole blood and serum in 343 paired samples at regular intervals up to 24 months postoperatively. Cobalt whole blood and serum levels increased significantly after both procedures. Cobalt concentrations were significantly higher for the HR group compared to the THA group, at 3, 6 and 12 months, for whole blood and serum. At 24 months cobalt levels decreased and differences between HR and THA were no longer significant. In contrast, chromium whole blood levels remained significantly higher for HR until 24 months. Whole blood and serum levels could not be used interchangeably. The mean differences for cobalt and chromium between blood and serum values were +0.13 µg/L and -0.91 µg/L respectively. Regression analysis provided a formula for conversion from serum to blood of 0.34+[0.88*Co serum] for cobalt and 0.14 + [0.58*Cr serum] for chromium, with an acceptable prediction error below ±1.0 µg/L. Cobalt and chromium levels were significantly higher for HR versus THA, especially during the run-in phase of one year. Overall, the metal ion levels were well below 5 µg/L. We cannot recommend the use of whole blood over serum measurements or vice versa. The provided conversion formula between whole blood and serum in combination with the presented practical guidelines may be useful for clinical practice.

  8. Imprinted polymers for the removal of heavy metal ions from water.

    Ashraf, Syed; Cluley, Angela; Mercado, Ckarlos; Mueller, Anja


    In wastewater treatment, the removal of heavy metals is difficult due to the limited affinity of heavy metal ions to ion exchange resins. Here imprinting polymerization is used to develop resins with high capacity and selectivity for heavy metal ions for water treatment. A random copolymer of methacrylate and methacrylamide was found to be most effective for the removal of hydrophilic metal complexes, like CdCl2, ZnCI2, and the metalloid NaH2AsO4, particularly when the porosity of these resins is increased. For hydrophobic complexes imprinting emulsion polymerization was developed and data for the effective removal of mercury dithizonate will be described. Complete removal for up to 80 ppm of cadmium and mercury with only 200 mg of imprinted resin was obtained; competition and co-imprinting experiments are described as well.

  9. Evaluation of IDA-PEVA hollow fiber membrane metal ion affinity chromatography for purification of a histidine-tagged human proinsulin.

    de Aquino, Luciana Cristina Lins; de Sousa, Heloisa Ribeiro Tunes; Miranda, Everson Alves; Vilela, Luciano; Bueno, Sônia Maria Alves


    Inabilities to process particulate material and to allow the use of high flow rates are limitations of conventional chromatography. Membranes have been suggested as matrix for affinity separation due to advantages such as allowing high flow rates and low-pressure drops. This work evaluated the feasibility of using an iminodiacetic acid linked poly(ethylenevinyl alcohol) membrane in the immobilized metal ion affinity chromatography (IMAC) purification of a human proinsulin(His)(6) of an industrial insulin production process. The screening of metal ions showed Ni(2+) as metal with higher selectivity and capacity among the Cu(2+), Ni(2+), Zn(2+) and Co(2+). The membrane showed to be equivalent to conventional chelating beads in terms of selectivity and had a lower capacity (3.68 mg/g versus 12.26 mg/g). The dynamic adsorption capacity for human proinsulin(His)(6) was unaffected by the mode of operation (dead-end and cross-flow filtration).

  10. Study of Ion Dynamics by Electron Transfer Dissociation: Alkali Metals as Targets

    Hayakawa, Shigeo


    High energy collision processes for singly charged positive ions using an alkali metal target are confirmed, as a charge inversion mass spectrometry, to occur by electron transfers in successive collisions and the dissociation processes involve the formation of energy-selected neutral species from near-resonant neutralization with alkali metal targets. A doubly charged thermometer molecule was made to collide with alkali metal targets to give singly and doubly charged positive ions. The internal energy resulting from the electron transfer with the alkali metal target was very narrow and centered at a particular energy. This narrow internal energy distribution can be attributed to electron transfer by Landau–Zener potential crossing between the precursor ion and an alkali metal atom, and the coulombic repulsion between singly charged ions in the exit channel. A large cross section of more than 10−14 cm2 was estimated for high-energy electron transfer dissociation (HE-ETD). Doubly protonated phosphorylated peptides obtained by electrospray ionization were collided with Xe and Cs targets to give singly and doubly charged positive ions. Whereas doubly charged fragment ions resulting from CAD were dominant in the case of the Xe target, singly charged fragment ions resulting from ETD were dominant with the Cs target. HE-ETD using the Cs target provided all of the z-type ions by N–Cα bond cleavage without the loss of the phosphate groups. The results demonstrate that HE-ETD with an alkali metal target allowed the position of phosphorylation and the amino acid sequence of peptides with post translational modifications (PTM) to be determined. PMID:28966899

  11. Real-time detection of metal ions using conjugated polymer composite papers.

    Lee, Ji Eun; Shim, Hyeon Woo; Kwon, Oh Seok; Huh, Yang-Il; Yoon, Hyeonseok


    Cellulose, a natural polymeric material, has widespread technical applications because of its inherent structural rigidity and high surface area. As a conjugated polymer, polypyrrole shows practical potential for a diverse and promising range of future technologies. Here, we demonstrate a strategy for the real-time detection and removal of metal ions with polypyrrole/cellulose (PPCL) composite papers in solution. Simply, the conjugated polymer papers had different chemical/physical properties by applying different potentials to them, which resulted in differentiable response patterns and adsorption efficiencies for individual metal ions. First, large-area PPCL papers with a diameter of 5 cm were readily obtained via vapor deposition polymerization. The papers exhibited both mechanical flexibility and robustness, in which polypyrrole retained its redox property perfectly. The ability of the PPCL papers to recognize metal ions was examined in static and flow cells, in which real-time current change was monitored at five different applied potentials (+1, +0.5, 0, -0.5, and -1 V vs. Ag/AgCl). Distinguishable signals in the PPCL paper responses were observed for individual metal ions through principal component analysis. Particularly, the PPCL papers yielded unique signatures for three metal ions, Hg(ii), Ag(i), and Cr(iii), even in a real sample, groundwater. The sorption of metal ions by PPCL papers was examined in the flow system. The PPCL papers had a greatly superior adsorption efficiency for Hg(ii) compared to that of the other metal ions. With the strong demand for the development of inexpensive, flexible, light-weight, and environmentally friendly devices, the fascinating characteristics of these PPCL papers are likely to provide good opportunities for low-cost paper-based flexible or wearable devices.

  12. Comparison of different transition metal ions for immobilized metal affinity chromatography of selenoprotein P from human plasma

    Sidenius, U; Farver, O; Jøns, O


    Cu2+, Ni2+, Zn2+, Co2+ and Cd2+ were evaluated in metal ion affinity chromatography for enrichment of selenoprotein P, and immobilized Co2+ affinity chromatography was found to be the most selective chromatographic method. The chromatography was performed by fast protein liquid chromatography and...

  13. Effects of transition metal ion identity and π-cation interactions in metal-bis(peptide) complexes containing phenylalanine.

    Utley, Brandon; Angel, Laurence A


    Electrospray ionization-tandem mass spectrometry was used to study the effects of the metal ion identity and π-cation interactions on the dissociation pathways of metal-bis(peptide) complexes, where the metal is either Mn(2+), Co(2+), Ni(2+), Cu(2+), or Zn(2+); and the peptide is either FGGF, GGGG, GF, or GG, where G is glycine and F is phenylalanine. The [(FGGF)(FGGF-H) + M(2+)](+) and [(GGGG)(GGGG-H) + M(2+)](+) complexes dissociated by losing one FGGF or GGGG, respectively. Relative binding affinities were measured using the crossover points, where the parent and product ions were equal in ion abundance and a normalized-collision energy scale. The results indicate the relative binding affinities for FGGF and GGGG follow the same order with respect to the transition metal ion identity: Cu(2+) < Ni(2+) < Mn(2+) ≈ Zn(2+) < Co(2+), and the π-cation interactions in the FGGF complex have a measureable stabilizing effect. In contrast, the main fragmentation channels of [(GF)(GF-H) + M(2+)]+ and [(GG)(GG-H) + M(2+)](+) are loss of CO(2) and 2CO(2) with the [(GF)(GF-H) + M(2+)](+) complex also exhibiting cinnamic acid ,GF, residual glycine, cinnamate and styrene loss.

  14. Changes in the levels of phytochelatins and related metal-binding peptides in chickpea seedlings exposed to arsenic and different heavy metal ions.

    Gupta, Dharmendra K; Tohoyama, Hiroshi; Joho, Masanori; Inouhe, Masahiro


    Phytochelatin-related peptides were analyzed in chickpea plants exposed to six different heavy-metal ions. Cadmium and arsenic stimulated phytochelatin and homophytochelatin synthesis in roots but other metals did not. These metals, however, caused an overall increase in the precursors, glutathione, homoglutathione and cysteine. These changes may be different biochemical indexes for heavy-metal contamination.

  15. Effect of metal ions on reactive dye decolorization by laccase from Ganoderma lucidum.

    Murugesan, Kumarasamy; Kim, Young-Mo; Jeon, Jong-Rok; Chang, Yoon-Seok


    In this work, the influence of different metal ions on laccase activity and laccase-catalyzed dye decolorization was investigated under in vitro conditions using crude laccase obtained from a white rot fungus Ganoderma lucidum. Laccase activity was enhanced by metal ions such as Ca(2+), Co(2+), Cu(2+) and Zn(2+) at low concentrations (1mM). Increasing the concentration of metal ions except that of Cu(2+) and Zn(2+) up to 5mM and above decreased the enzyme activity. Among several heavy metals, Fe(2+) highly inhibited the enzyme activity. Effect of metal ions was tested on decolorization of two reactive dyes, namely Remazol black-B (RB-5) and Remazol brilliant blue R (RBBR) at a concentration of 50 mg l(-1). The presence of heavy metals generally did not exert much influence on the decolorization except Fe(2+). Cu(2+) and Cr(6+) enhanced the decolorization of both dyes. In the presence of 1mM Cu(2+), 94% of RB-5 and 35.5% of RBBR were decolorized during 1h incubation. G. lucidum laccase was able to tolerate mixture of several metal ions. Treatment of simulated reactive dye effluent by laccase showed that the redox mediator system is necessary for effluent decolorization. Syringaldehyde, a natural redox mediator, was very effective than the synthetic mediator 1-hydroxybenzotriazole (HBT). The initial rate of effluent decolorization in presence of syringaldehyde (0.0831 h(-1)) was 5.6 times higher than HBT (0.0152 h(-1)). Although the rate of decolorization was markedly decreased in the effluent containing mixed metal ions, presence of syringaldehyde showed effective decolorization. This study indicates that G. lucidum laccase and natural redox mediator system could be a potential candidate for color removal from reactive dye effluent.

  16. Designing antimicrobial bioactive glass materials with embedded metal ions synthesized by the sol–gel method

    Palza, Humberto, E-mail: [Departamento de Ingeniería Química y Biotecnología, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Santiago (Chile); Escobar, Blanca; Bejarano, Julian [Departamento de Ingeniería Química y Biotecnología, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Santiago (Chile); Bravo, Denisse [Departamento de Patología, Facultad de Odontología, Universidad de Chile, Santiago (Chile); Diaz-Dosque, Mario [Departamento de Ciencias Básicas y Comunitarias, Facultad de Odontología, Universidad de Chile, Santiago (Chile); Perez, Javier [Departamento de Ingeniería Química y Biotecnología, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Santiago (Chile)


    Bioactive glasses (SiO{sub 2}–P{sub 2}O{sub 5}–CaO) having tailored concentrations of different biocide metal ions (copper or silver) were produced by the sol–gel method. All the particles release phosphorous ions when immersed in water and simulated body fluid (SBF). Moreover, a surface layer of polycrystalline hydroxy-carbonate apatite was formed on the particle surfaces after 10 day immersion in SBF as confirmed by X-ray diffraction and scanning electron microscopy (SEM) showing the bioactive materials. Samples with embedded either copper or silver ions were able to further release the biocide ions with a release rate that depends on the metal embedded and the dissolution medium: water or SBF. This biocide ion release from the samples explains the antimicrobial effect of our active particles against Escherichia coli DH5α ampicillin-resistant (Gram-negative) and Streptococcus mutans (Gram-positive) as determined by the Minimum Bactericidal Concentration (MBC) method. The antimicrobial behavior of the particles depends on the bacteria and the biocide ion used. Noteworthy, although samples with copper are able to release more metal ion than samples with silver, they present higher MBC showing the high effect of silver against these bacteria. - Highlights: • Copper and silver act as antimicrobial additives in bioactive glass materials. • Silver is more toxic than copper ions in these bioactive materials. • Sol–gel method allows the synthesis of antimicrobial bioactive materials.

  17. Types and concentrations of metal ions affect local structure and dynamics of RNA

    Wang, Jun; Xiao, Yi


    The roles that metal ions play in the structure and dynamics of RNA molecules are long-standing problems that have been studied extensively but are still not well understood. Here we show that metal ions have distributions around RNA molecules that strongly depend on the types and concentrations of the metal ions and also the electrostatic surface of the molecule. In particular, the ion distributions may not balance all the local electronegativity of the molecule. These ion distributions do not only greatly affect local structures but also lead to different local dynamics of RNA. We studied the effects of different ion solutions on the structure and dynamics of RNA by taking the pre Q1 riboswitch aptamer domain as an illustrative example and using molecular dynamics simulations. Since the local structures and dynamics of RNAs are important to their functions, our results also indicate that the selection of proper ion conditions is necessary to model them correctly, in contrast to the use of diverse ion solutions in current molecular dynamics simulations.

  18. Proton and metal ion binding to humic substances.

    Wit, de J.C.M.


    Humic substances are polydisperse mixtures of organic molecules which at least to some extent determine the mobility and bioavailability of heavy metals in soils, sediments and aquatic systems. In order to make a sound risk assessment of the fate of trace metals a good conception and preferably a so

  19. Sorption of Heavy Metal Ions from Mine Wastewater by Activated ...



    Dec 2, 2016 ... tailings disposal, illegal mining, domestic waste disposal and many .... Waste water sample for the test work was collected ..... “Heavy Metal Contamination of Ground. Water”. ... metallurgy, waste management, pyrolysis-gasification of wastes ... of waste polymers in metal extraction processes and recycling.

  20. Porous graphene-based membranes for water purification from metal ions at low differential pressures.

    Park, Jaewoo; Bazylewski, Paul; Fanchini, Giovanni


    A new generation of membranes for water purification based on weakly oxidized and nanoporous few-layer graphene is here introduced. These membranes dramatically decrease the high energy requirements of water purification by reverse osmosis. They combine the advantages of porous and non-oxidized single-layer graphene, offering energy-efficient water filtration at relatively low differential pressures, and highly oxidized graphene oxide, exhibiting high performance in terms of impurity adsorption. In the reported fabrication process, leaks between juxtaposed few-layer graphene flakes are sealed by thermally annealed colloidal silica, in a treatment that precedes the opening of (sub)nanometre-size pores in graphene. This process, explored for the first time in this work, results in nanoporous graphene flakes that are water-tight at the edges without occluding the (sub)nanopores. With this method, removal of impurities from water occurs through a combination of size-based pore rejection and pore-edge adsorption. Thinness of graphene flakes allows these membranes to achieve water purification from metal ions in concentrations of few parts-per-million at differential pressures as low as 30 kPa, outperforming existing graphene or graphene oxide purification systems with comparable flow rates.

  1. Hollow metal target magnetron sputter type radio frequency ion source

    Yamada, N., E-mail:; Kasuya, T.; Wada, M. [Graduate School of Science and Engineering, Doshisha University, Kyoto 610–0321 (Japan); Tsubouchi, N. [Kansai Institute, Advanced Industrial Science and Technology, Osaka 563–8577 (Japan)


    A 70 mm diameter 70 mm long compact ion source equipped with a hollow sputtering target has been designed and tested. The hollow sputtering target serves as the radio frequency (RF) plasma excitation electrode at 13.56 MHz. A stable beam of Cu{sup +} has been extracted when Ar was used as the discharge support gas. In the extracted beam, Cu{sup +} had occupied more than 85% of the total ion current. Further increase in Cu{sup +} ions in the beam is anticipated by increasing the RF power and Ar pressure.

  2. Selective fluorescence sensors for detection of nitroaniline and metal Ions based on ligand-based luminescent metal-organic frameworks

    Yu, Zongchao [College of Environment and Chemical Engineering & Key Lab of Hollow Fiber Membrane Materials & Membrane Process, Tianjin Polytechnic University, Tianjin 300387 (China); Wang, Fengqin, E-mail: [College of Environment and Chemical Engineering & Key Lab of Hollow Fiber Membrane Materials & Membrane Process, Tianjin Polytechnic University, Tianjin 300387 (China); Lin, Xiangyi [Suzhou Huihe Pharmaceutical Limited Company, Suzhou 215200 (China); Wang, Chengmiao; Fu, Yiyuan; Wang, Xiaojun [College of Environment and Chemical Engineering & Key Lab of Hollow Fiber Membrane Materials & Membrane Process, Tianjin Polytechnic University, Tianjin 300387 (China); Zhao, Yongnan [College of Materials and Engineering & Key Lab of Hollow Fiber Membrane Materials & Membrane Process, Tianjin Polytechnic University, Tianjin 300387 (China); Li, Guodong [The State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, Jilin University, Changchun 130023 (China)


    Metal-organic frameworks (MOFs) are porous crystalline materials with high potential for applications in fluorescence sensors. In this work, two solvent-induced Zn(II)–based metal-organic frameworks, Zn{sub 3}L{sub 3}(DMF){sub 2} (1) and Zn{sub 3}L{sub 3}(DMA){sub 2}(H{sub 2}O){sub 3} (2) (L=4,4′-stilbenedicarboxylic acid), were investigated as selective sensing materials for detection of nitroaromatic compounds and metal ions. The sensing experiments show that 1 and 2 both exhibit selective fluorescence quenching toward nitroaniline with a low detection limit. In addition, 1 exhibits high selectivity for detection of Fe{sup 3+} and Al{sup 3+} by significant fluorescence quenching or enhancement effect. While for 2, it only exhibits significant fluorescence quenching effect for Fe{sup 3+}. The results indicate that 1 and 2 are both promising fluorescence sensors for detecting and recognizing nitroaniline and metal ions with high sensitivity and selectivity. - Graphical abstract: Two MOFs have been selected as the fluorescence sensing materials for selectively sensing mitroaromatic compounds and metal ions. The high selectivity makes them promising fluorescence sensors for detecting and recognizing nitroaniline and Fe{sup 3+} or Al{sup 3+}.

  3. Some estimates of the virtual source size of a liquid metal ion source

    Georgieva, S.; Vichev, R.G.; Drandarov, N. (Bylgarska Akademiya na Naukite, Sofia (Bulgaria). Inst. po Elektronika)

    A Monte Carlo computer code simulating the trajectories of ions emitted from a liquid metal ion source (LMIS) is developed. The electric field of the tip is taken to be that created by a sphere-on-orthogonal cone. The ions are emitted normal to the surface with an initial energy of 1 eV. A Poisson distribution is used to describe the time dependence of their emission process. Ion trajectories are followed and the virtual source size and energy spectra are evaluated for three reference planes normal to the emitter axis. The obtained results are compared with the experimentally measured values. (author).

  4. Effect of Different Metal Ions on the Biological Properties of Cefadroxil

    Reinhard H. H. Neubert


    Full Text Available The effect of different metal ions on the intestinal transport and the antibacterial activity of cefadroxil [(6R,7R-7-{[(2R-2-amino-2-(4-hydroxyphenylacetyl]amino}-3-methyl-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid] was investigated. The [14C]Gly-Sar uptake via PEPT1 was inhibited by Zn2+ and Cu2+ treatment in a concentration-dependent manner (Ki values 107 ± 23 and 19 ± 5 μM, respectively. Kinetic analysis showed that the Kt of Gly-Sar uptake was increased 2-fold in the presence of zinc sulphate (150 μM whereas the Vmax value were not affected suggesting that zinc ions inhibited Gly-Sar uptake by PEPT1 in a competitively manner. Ni2+ exhibited moderate inhibitory effect, whereas Co2+, Mg2+, Al3+ ions showed no inhibitory effect on Gly-Sar uptake via PEPT1. Subsequently, we examined the effect of Zn2+ and Al3+ ions on the transepithelial transport of cefadroxil across Caco-2 cells cultured on permeable supports. The results showed that zinc ions inhibited the transepithelial flux of cefadroxil at Caco-2 cell monolayers while Al3+ ions had no effect. The interaction of cephalosporins with the metal ions could suggest negative effects of some metal ions on the clinical aspects of small intestinal peptide and drug transport. Finally, the effect of Zn2+, Cu2+ and Al3+ ions on the antibacterial activity of cefadroxil was tested. It was found that there is no significant difference between the activity of cefadroxil and the cefadroxil metal ion complexes studied against the investigated sensitive bacterial species.

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

    Anoop, K. K., E-mail:; Bruzzese, R.; Amoruso, S. [CNR-SPIN and Dipartimento di Fisica, Universita degli Studi di Napoli Federico II, Complesso Universitario Monte S. Angelo, Via Cintia, Napoli 80126 (Italy); Polek, M. P. [Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Harilal, S. S. [Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352 (United States)


    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.

  6. Adsorption of endotoxins on Ca2+-iminodiacetic acid by metal ion affinity chromatography

    André Moreni LOPES; Jorge Sánchez ROMEU; Rolando Páez MEIRELES; Gabriel Marquez PERERA; Rolando Perdomo MORALES; Adalberto PESSOA; Lourdes Zumalacárregui CáRDENAS


    Endotoxins (also known as lipopolysaccharides (LPS)) are undesirable by-products of recombinant proteins,purified from Escherichia coli.LPS can be considered stable under a wide range of temperature and pH,making their removal one of the most difficult tasks in downstream processes during protein purification.The inherent toxicity of LPS makes their removal an important step for the application of these proteins in several biological assays and for a safe parenteral administration.Immobilized metal affinity chromatography (IMAC) enables the affinity interactions between the metal ions (immobilized on the support through the chelating compound) and the target molecules,thus enabling high-efficiency separation of the target molecules from other components present in a mixture.Affinity chromatography is applied with Ca2+-iminodiacetic acid (IDA)to remove most of the LPS contaminants from the end product (more than 90%).In this study,the adsorption of LPS on an IDA-Ca2+ was investigated.The adsorption Freundlich isotherm of LPS-IDA-Ca2 + provides a theoretical basis for LPS removal.It was found that LPS is bound mainly by interactions between the phosphate group in LPS and Ca2+ ligands on the beads.The factors such as pH (4.0 or 5.5) and ionic strength (1.0 mol/L) are essential to obtain effective removal of LPS for contaminant levels between endotoxin' concentration values less than 100 EU/mL and 100000 EU/mL.This new protocol represents a substantial advantage in time,effort,and production costs.

  7. Protein scaffolds for selective enrichment of metal ions

    He, Chuan; Zhou, Lu; Bosscher, Michael


    Polypeptides comprising high affinity for the uranyl ion are provided. Methods for binding uranyl using such proteins are likewise provided and can be used, for example, in methods for uranium purification or removal.

  8. Asymptomatic prospective and retrospective cohorts with metal-on-metal hip arthroplasty indicate acquired lymphocyte reactivity varies with metal ion levels on a group basis.

    Hallab, Nadim J; Caicedo, Marco; McAllister, Kyron; Skipor, Anastasia; Amstutz, Harlan; Jacobs, Joshua J


    Some tissues from metal-on-metal (MoM) hip arthroplasty revisions have shown evidence of adaptive-immune reactivity (i.e., excessive peri-implant lymphocyte infiltration/activation). We hypothesized that, prior to symptoms, some people with MoM hip arthroplasty will develop quantifiable metal-induced lymphocyte reactivity responses related to peripheral metal ion levels. We tested three cohorts (Group 1: n = 21 prospective longitudinal MoM hip arthroplasty; Group 2: n = 17 retrospective MoM hip arthroplasty; and Group 3: n = 20 controls without implants). We compared implant position, metal-ion release, and immuno-reactivity. MoM cohorts had elevated (p Group 1:1.2 ppb Co, 1.5 ppb Cr; Group 2: 3.4 ppb Co, 5.4 ppb Cr; Group 3: 0.01 ppb Co, 0.1 ppb Cr). However, only after 1-4 years post-op did 56% of Group 1 develop metal-reactivity (vs. 5% pre-op, metal-LTT, SI > 2), compared with 76% of Group 2, and 15% of Group 3 controls (patch testing was a poor diagnostic indicator with only 1/21 Group 1 positive). Higher cup-abduction angles (50° vs. 40°) in Group 1 were associated with higher serum Cr (p Group-1 participants (p Group 1 participants. Our results showed that lymphocyte reactivity to metals can develop within the first 1-4 years after MoM arthroplasty in asymptomatic patients and lags increases in metal ion levels. This increased metal reactivity was more prevalent in those individuals with extreme cup angles and higher amounts of circulating metal. Copyright © 2012 Orthopaedic Research Society.

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

    Zhang, Jianhua; Wang, Naiyan; Zhang, Fengshou


    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.

  10. Quenching of tryptophan fluorescence of bovine serum albumin under the effect of ions of heavy metals

    Plotnikova, O. A.; Mel'nikov, A. G.; Mel'nikov, G. V.; Gubina, T. I.


    The interaction of heavy metals with bovine serum albumin (BSA) has been studied using data of quenching of intrinsic fluorescence of the protein by the ions of the heavy metals. Under the assumption of static quenching with formation of nonfluorescent complexes of fluorophores of BSA with heavy metals, conclusions have been drawn on the peculiarities of binding of the heavy metals to the protein. The values of the Stern-Volmer constants of association and those of the constants of BSA binding to the heavy metals decrease in the order Cu(II) > Pb(II) > Cd(II). It has been experimentally found that the copper ions have greater capacity to bind to the protein with the formation of the nonfluorescent complexes, which results in a significant decrease in the fluorescence intensity of the protein.

  11. The Analysis of Metal Finishing Solutions by Ion Chromatography


    but some Cr(III) is produced during the electrolysis and can negatively effect plate properties and plating efficiency (67, 68). In an operating system... Brines by Indirect Atomic Absorption Spectroscopy", Chem. Prum., 33, 8, 429- 435 (1983). 17. D. Jones, S. Manahan, "Atomic Absorption Detector For... Brine ", J. Chromatogr., 250, 134-7 (1982). 24. T. Nishina, "Analysis of Sulfate Ion by Ion Chromatography", Yogyo Kyokaishi, 92, 7, 410-2 (1984). 25. S

  12. Scanning microbeam using a liquid metal ion source

    Ishitani, T.; Tamura, H.; Todokoro, H.


    A scanning ion microprobe system using a liquid-Ga ion source and a voltage-asymmetric three-electrode lens is developed. It produces 2--20 keV Ga/sup +/ beams of 0.1--5 diameter with 20 pA--8 nA current. Beam sizes are directly measured by a combined sharp-edge and Faraday cup mehtod. This optical system is well suited for variable energy microprobe applications.

  13. Alkali-Metal-Ion-Functionalized Graphene Oxide as a Superior Anode Material for Sodium-Ion Batteries.

    Wan, Fang; Li, Yu-Han; Liu, Dai-Huo; Guo, Jin-Zhi; Sun, Hai-Zhu; Zhang, Jing-Ping; Wu, Xing-Long


    Although graphene oxide (GO) has large interlayer spacing, it is still inappropriate to use it as an anode for sodium-ion batteries (SIBs) because of the existence of H-bonding between the layers and ultralow electrical conductivity which impedes the Na(+) and e(-) transformation. To solve these issues, chemical, thermal, and electrochemical procedures are traditionally employed to reduce GO nanosheets. However, these strategies are still unscalable, consume high amounts of energy, and are expensive for practical application. Here, for the first time, we describe the superior Na storage of unreduced GO by a simple and scalable alkali-metal-ion (Li(+) , Na(+) , K(+) )-functionalized process. The various alkali metals ions, connecting with the oxygen on GO, have played different effects on morphology, porosity, degree of disorder, and electrical conductivity, which are crucial for Na-storage capabilities. Electrochemical tests demonstrated that sodium-ion-functionalized GO (GNa) has shown outstanding Na-storage performance in terms of excellent rate capability and long-term cycle life (110 mAh g(-1) after 600 cycles at 1 A g(-1) ) owing to its high BET area, appropriate mesopore, high degree of disorder, and improved electrical conductivity. Theoretical calculations were performed using the generalized gradient approximation (GGA) to further study the Na-storage capabilities of functionalized GO. These calculations have indicated that the Na-O bond has the lowest binding energy, which is beneficial to insertion/extraction of the sodium ion, hence the GNa has shown the best Na-storage properties among all comparatives functionalized by other alkali metal ions.

  14. Droplet-free high-density metal ion source for plasma immersion ion implantation

    Nakamura, Keiji [Department of Electrical Engineering, College of Engineering, Chubu University, 1200 Matsumoto, Kasugai, Aichi 487-8501 (Japan)]. E-mail:; Yoshinaga, Hiroaki [Department of Electrical Engineering, Doshisha University, 1-3 Tatara Miyakodani, Kyotanabe, Kyoto 610-0321 (Japan); Yukimura, Ken [Department of Electrical Engineering, Doshisha University, 1-3 Tatara Miyakodani, Kyotanabe, Kyoto 610-0321 (Japan)


    This paper reports on plasma parameters and ion composition of droplet-free Zr ion source for plasma immersion ion implantation and deposition (PIII and D). Zirconium (Zr) ions were obtained by ionizing sputtered Zr atoms in inductively-coupled argon discharge. The characteristics of plasma density, plasma potential and electron temperature were typical ones of such a inductive discharge, and the plasma parameters were not significantly influenced by mixing the sputtered Zr atoms into the plasma. Actually, the main ionic component was still Ar{sup +} ions, and the ion density ratio of [Zr{sup +}]/[Ar{sup +}] was as low as {approx}8%. Increase in sputtering rate of the Zr source will be necessary to improve the ion density ratio.

  15. Heavy metal removal from waste waters by ion flotation.

    Polat, H; Erdogan, D


    Flotation studies were carried out to investigate the removal of heavy metals such as copper (II), zinc (II), chromium (III) and silver (I) from waste waters. Various parameters such as pH, collector and frother concentrations and airflow rate were tested to determine the optimum flotation conditions. Sodium dodecyl sulfate and hexadecyltrimethyl ammonium bromide were used as collectors. Ethanol and methyl isobutyl carbinol (MIBC) were used as frothers. Metal removal reached about 74% under optimum conditions at low pH. At basic pH it became as high as 90%, probably due to the contribution from the flotation of metal precipitates.

  16. Determination of metal ion content of beverages and estimation of target hazard quotients: a comparative study

    Barker James


    Full Text Available Abstract Background Considerable research has been directed towards the roles of metal ions in nutrition with metal ion toxicity attracting particular attention. The aim of this study is to measure the levels of metal ions found in selected beverages (red wine, stout and apple juice and to determine their potential detrimental effects via calculation of the Target Hazard Quotients (THQ for 250 mL daily consumption. Results The levels (mean ± SEM and diversity of metals determined by ICP-MS were highest for red wine samples (30 metals totalling 5620.54 ± 123.86 ppb followed by apple juice (15 metals totalling 1339.87 ± 10.84 ppb and stout (14 metals totalling 464.85 ± 46.74 ppb. The combined THQ values were determined based upon levels of V, Cr, Mn, Ni, Cu, Zn and Pb which gave red wine samples the highest value (5100.96 ± 118.93 ppb followed by apple juice (666.44 ± 7.67 ppb and stout (328.41 ± 42.36 ppb. The THQ values were as follows: apple juice (male 3.11, female 3.87, stout (male 1.84, female 2.19, red wine (male 126.52, female 157.22 and ultra-filtered red wine (male 110.48, female 137.29. Conclusion This study reports relatively high levels of metal ions in red wine, which give a very high THQ value suggesting potential hazardous exposure over a lifetime for those who consume at least 250 mL daily. In addition to the known hazardous metals (e.g. Pb, many metals (e.g. Rb have not had their biological effects systematically investigated and hence the impact of sustained ingestion is not known.

  17. Metal ion-mediated agonism and agonist enhancement in melanocortin MC1 and MC4 receptors

    Holst, Birgitte; Elling, Christian E; Schwartz, Thue W


    An endogenous metal-ion site in the melanocortin MC1 and MC4 receptors was characterized mainly in transiently transfected COS-7 cells. ZnCl(2) alone stimulated signaling through the Gs pathway with a potency of 11 and 13 microm and an efficacy of 50 and 20% of that of alpha-melanocortin stimulat......An endogenous metal-ion site in the melanocortin MC1 and MC4 receptors was characterized mainly in transiently transfected COS-7 cells. ZnCl(2) alone stimulated signaling through the Gs pathway with a potency of 11 and 13 microm and an efficacy of 50 and 20% of that of alpha...... of the metal ion appeared to be additive, because the maximal cAMP response for alpha-MSH in the presence of Zn(II) was 60% above the maximal response for the peptide alone. The affinity of Zn(II) could be increased through binding of the metal ion in complex with small hydrophobic chelators. The binding...... affinities and profiles were similar for a number of the 2,2'-bipyridine and 1,10-phenanthroline analogs in complex with Zn(II) in the MC1 and MC4 receptors. However, the potencies and efficacies of the metal-ion complexes were very different in the two receptors, and close to full agonism was obtained...

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

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


    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.

  19. Antibacterial properties of metal and metalloid ions in chronic periodontitis and peri-implantitis therapy.

    Goudouri, Ourania-Menti; Kontonasaki, Eleana; Lohbauer, Ulrich; Boccaccini, Aldo R


    Periodontal diseases like periodontitis and peri-implantitis have been linked with Gram-negative anaerobes. The incorporation of various chemotherapeutic agents, including metal ions, into several materials and devices has been extensively studied against periodontal bacteria, and materials doped with metal ions have been proposed for the treatment of periodontal and peri-implant diseases. The aim of this review is to discuss the effectiveness of materials doped with metal and metalloid ions already used in the treatment of periodontal diseases, as well as the potential use of alternative materials that are currently available for other applications but have been proved to be cytotoxic to the specific periodontal pathogens. The sources of this review included English articles using Google Scholar™, ScienceDirect, Scopus and PubMed. Search terms included the combinations of the descriptors "disease", "ionic species" and "bacterium". Articles that discuss the biocidal properties of materials doped with metal and metalloid ions against the specific periodontal bacteria were included. The articles were independently extracted by two authors using predefined data fields. The evaluation of resources was based on the quality of the content and the relevance to the topic, which was evaluated by the ionic species and the bacteria used in the study, while the final application was not considered as relevant. The present review summarizes the extensive previous and current research efforts concerning the use of metal ions in periodontal diseases therapy, while it points out the challenges and opportunities lying ahead.

  20. Anion-intercalated layered double hydroxides modified test strips for detection of heavy metal ions.

    Wang, Nan; Sun, Jianchao; Fan, Hai; Ai, Shiyun


    In this work, a novel approach for facile and rapid detection of heavy metal ions using anion-intercalated layered double hydroxides (LDHs) modified test strips is demonstrated. By intercalating Fe(CN)6(4-) or S(2-) anions into the interlayers of LDHs on the filter paper, various heavy metal ions can be easily detected based on the color change before and after reaction between the anions and the heavy metal ions. Upon the dropping of heavy metal ions solutions to the test strips, the colors of the test strips changed instantly, which can be easily observed by naked eyes. With the decrease of the concentration, the color depth changed obviously. The lowest detection concentration can be up to 1×10(-6) mol L(-1). Due to the easily intercalation of anions into the interlayer of the LDHs on test trips, this procedure provides a general method for the construction of LDHs modified test strips for detection of heavy metal ions. The stability of the prepared test strips is investigated. Furthermore, all the results were highly reproducible. The test strips may have potential applications in environmental monitoring fields.

  1. Effect Of Metal Ions On Triphenylmethane Dye Decolorization By Laccase From Trametes Versicolor

    Chmelová Daniela


    Full Text Available The aim of this study was investigate the influence of different metal ions on laccase activity and triphenylmethane dye decolorization by laccase from white-rot fungus Trametes versicolor. Laccase activity was inhibited by monovalent ions (Li+, Na+, K+ and Ag+ but the presence of divalent ions increased laccase activity at the concentration of 10 mmol/l. The effect of metal ions on decolorization of triphenylmethane dyes with different structures namely Bromochlorophenol Blue, Bromophenol Blue, Bromocresol Blue and Phenol Red was tested. The presence of metal ions (Na+, K+, Mg2+, Ca2+, Ba2+, Mn2+, Zn2+ slightly decreased triphenylmethane dye decolorization by laccase from T. versicolor except Na+ and Mg2+, which caused the increase of decolorization for all tested dyes. Decolorization of selected dyes showed that the presence of low-molecular-weight compounds is necessary for effective decolorization. Hydroxybenzotriazole (HBT is the most frequently used. Although HBT belongs to most frequently used redox mediator and generally increase decolorization efficiency, so its presence decreased decolorization percentage of Bromophenol Blue and Bromochlorophenol Blue, the influence of metal ions to dye decolorization by laccase has the similar course with or without presence of redox mediator HBT.

  2. Formation of Multicharged Metal Ions in Vacuum Arc Plasma Heated by Gyrotron Radiation%Formation of Multicharged Metal Ions in Vacuum Arc Plasma Heated by Gyrotron Radiation



    A new method for the generation of high charged state metal ion beams is developed. This method is based on microwave heating of vacuum arc plasma in a magnetic trap under electron cyclotron resonance (ECR) conditions. Two gyrotrons for plasma heating were used, which were with the following parameters. The first is with a wave frequency of 37.5 GHz, a pulse duration of 1 ms and power of 100 kW, another is with 75 GHz, 0.15 ms and 400 kW. Two different magnetic traps were considered for vacuum arc plasma confinement. The first one is a simple mirror trap. Such system was already investigated and could provide high charge state ions. The second trap was with a cusp magnetic field configuration with native "minimum-B" field structure. Two different ways of metal plasma injection into the magnetic trap were used. The first one is an axial injection from an arc source located out of the trap, and the second is a radial injection from four arc sources mounted at the center of the trap. Both traps provide up to 200 eMA of ion beam current for platinum ions with highest charge state 10+. Ion beams were successfully extracted from the plasma and accelerated by a voltage of up to 20 kV.

  3. Carbon dots rooted agarose hydrogel hybrid platform for optical detection and separation of heavy metal ions.

    Gogoi, Neelam; Barooah, Mayuri; Majumdar, Gitanjali; Chowdhury, Devasish


    A robust solid sensing platform for an on-site operational and accurate detection of heavy metal is still a challenge. We introduce chitosan based carbon dots rooted agarose hydrogel film as a hybrid solid sensing platform for detection of heavy metal ions. The fabrication of the solid sensing platform is centered on simple electrostatic interaction between the NH3+ group present in the carbon dots and the OH- groups present in agarose. Simply on dipping the hydrogel film strip into the heavy metal ion solution, in particular Cr6+, Cu2+, Fe3+, Pb2+, Mn2+, the strip displays a color change, viz., Cr6+→yellow, Cu2+→blue, Fe3+→brown, Pb2+→white, Mn2+→tan brown. The optical detection limit of the respective metal ion is found to be 1 pM for Cr6+, 0.5 μM for Cu2+, and 0.5 nM for Fe3+, Pb2+, and Mn2+ by studying the changes in UV-visible reflectance spectrum of the hydrogel film. Moreover, the hydrogel film finds applicability as an efficient filtration membrane for separation of these quintet heavy metal ions. The strategic fundamental feature of this sensing platform is the successful capability of chitosan to form colored chelates with transition metals. This proficient hybrid hydrogel solid sensing platform is thus the most suitable to employ as an on-site operational, portable, cheap colorimetric-optical detector of heavy metal ion with potential skill in their separation. Details of the possible mechanistic insight into the colorimetric detection and ion separation are also discussed.

  4. Fluorescence signalling of the transition metal ions: Design strategy based on the choice of the fluorophore component

    N B Sankaran; S Banthia; A Samanta


    Transition metal ions are notorious for their fluorescence quenching abilities. In this paper, we discuss the design strategies for the development of efficient off-on fluorescence signalling systems for the transition metal ions. It is shown that even simple fluorophore-spacer-receptor systems can display excellent off-on fluorescence signalling towards the quenching metal ions when the fluorophore component is chosen judiciously.

  5. Bioleaching of metal ions from low grade sulphide ore: Process ...



    May 10, 2010 ... copper, gold, silver, platinum, chromium, iron, lead and zinc in various ... metal compounds into their water-soluble forms and are biocatalysts of this .... whose column elements represent the low, medium and high levels.

  6. Removal of some metal ions from aqueous solution using orange ...



    Sep 3, 2008 ... loped over the years to remove toxic metals from water. *Corresponding ... ed to stand for one hour and the product was collected by filtration, washed with .... activated charcoal derived from coconut shell. J. Environ. Agric.

  7. Ion activity and distribution of heavy metals in acid mine drainage polluted subtropical soils

    Li Yongtao [College of Natural Resources and Environment, South China Agricultural University, 510642 Guangzhou (China); Laboratoire de Geochimie des Eaux, Universite Paris-Diderot - IPGP, Case 7052, Batiment Lamarck, 75205 Paris Cedex 13 (France); Becquer, Thierry [UMR 137 Biodiversite et Fonctionnement des Sols, IRD/Universites Paris VI and XII, SupAgro - Bat. 12, 2 Place Viala, 34060 Montpellier Cedex 2 (France); Dai Jun [College of Natural Resources and Environment, South China Agricultural University, 510642 Guangzhou (China); Quantin, Cecile [UMR 8148 IDES, Universite Paris Sud XI - CNRS, Bat. 504, 91405 Orsay Cedex (France); Benedetti, Marc F. [Laboratoire de Geochimie des Eaux, Universite Paris-Diderot - IPGP, Case 7052, Batiment Lamarck, 75205 Paris Cedex 13 (France)], E-mail:


    The oxidative dissolution of mine wastes gives rise to acidic, metal-enriched mine drainage (AMD) and has typically posed an additional risk to the environment. The poly-metallic mine Dabaoshan in South China is an excellent test site to understand the processes affecting the surrounding polluted agricultural fields. Our objectives were firstly to investigate metal ion activity in soil solution, distribution in solid constituents, and spatial distribution in samples, secondly to determine dominant environment factors controlling metal activity in the long-term AMD-polluted subtropical soils. Soil Column Donnan Membrane Technology (SC-DMT) combined with sequential extraction shows that unusually large proportion of the metal ions are present as free ion in the soil solutions. The narrow range of low pH values prevents any pH effects during the binding onto oxides or organic matter. The differences in speciation of the soil solutions may explain the different soil degradation observed between paddy and non-paddy soils. - First evidence of the real free metal ion concentrations in acid mine drainage context in tropical systems.

  8. Immobilization study of biosorption of heavy metal ions onto activated sludge

    WU Hai-suo; ZHANG Ai-qiang; WANG Lian-sheng


    Activated sludge was immobilized into Ca-alginate beads via entrapment, and biosorption of three heavy metal ions, copper(Ⅱ), zinc(Ⅱ), and chromimum(Ⅱ), from aqueous solution in the concentration range of 10-100 mg/L was studied by using both entrapped activated sludge and inactivated free biomass at pH≤ 5. A biphasic metal adsorption pattern was observed in all immobilized biomass experiments. The biosorption of metal ions by the biosorbents increased with the initial concentration increased in the medium. The adsorption rate of immobilized pretreated activated sludge(PAS) was much lower than that of free PAS due to the increase in mass transfer resistance resulting from the polymeric matrix. Biosorption equilibrium of beads was established in about 20 h and the adsorbed heavy metal ions did not change further with time. No significant effect of temperature was observed in the test for free biomass while immobilized PAS appeared to be strong temperature dependent in the test range of 10 and 40℃.Besides, the content of activated sludge in the calcium alginate bead has an influence on the uptake of heavy metals. The sorption equilibrium was well modeled by Langmuir isotherm, implying monomolecular adsorption mechanism. Carboxyl group in cell wall played an important role in surface adsorption of heavy metal ions on PAS.

  9. Nanostructured metal oxide-based materials as advanced anodes for lithium-ion batteries.

    Wu, Hao Bin; Chen, Jun Song; Hng, Huey Hoon; Lou, Xiong Wen David


    The search for new electrode materials for lithium-ion batteries (LIBs) has been an important way to satisfy the ever-growing demands for better performance with higher energy/power densities, improved safety and longer cycle life. Nanostructured metal oxides exhibit good electrochemical properties, and they are regarded as promising anode materials for high-performance LIBs. In this feature article, we will focus on three different categories of metal oxides with distinct lithium storage mechanisms: tin dioxide (SnO(2)), which utilizes alloying/dealloying processes to reversibly store/release lithium ions during charge/discharge; titanium dioxide (TiO(2)), where lithium ions are inserted/deinserted into/out of the TiO(2) crystal framework; and transition metal oxides including iron oxide and cobalt oxide, which react with lithium ions via an unusual conversion reaction. For all three systems, we will emphasize that creating nanomaterials with unique structures could effectively improve the lithium storage properties of these metal oxides. We will also highlight that the lithium storage capability can be further enhanced through designing advanced nanocomposite materials containing metal oxides and other carbonaceous supports. By providing such a rather systematic survey, we aim to stress the importance of proper nanostructuring and advanced compositing that would result in improved physicochemical properties of metal oxides, thus making them promising negative electrodes for next-generation LIBs.

  10. Metal ion exchange process by natural and modified clinoptilolite

    Athanasiadis, K.; Petter, C.; Hilliges, R.; Helmreich, B.; Wilderer, P.A. [TU Muenchen (Germany). Lehrstuhl fuer Wasserguete- und Abfallwirtschaft


    Clinoptilolite, one of the most frequently studied natural zeolites, was shown to have high selectivity for certain heavy metals such as lead, cadmium and nickel. The aim of this study is to present equilibrium and kinetic data for Pb{sup 2+}, Cu{sup 2+} and Zn{sup 2+} exchange on natural and modified clinoptilolite for two different pH values. Selectivity series and kinetic data from these three heavy metals are presented. (orig.)

  11. Toxic Effects of Three Heavy Metallic Ions on Rana zhenhaiensis Tadpoles

    Li WEI; Guohua DING; Sainan GUO; Meiling TONG; Wenjun CHEN; Jon FLANDERS; Weiwei SHAO; Zhihua LIN


    Heavy metal pollution is widespread in some areas of China and results in contamination of land, water, and air with which all living organisms interact. In this study, we used three heavy metallic ions (Cu2+, Pb2+ and Zn2+) to assess their toxicity effects on mortality, blood biomarker and growth traits (body length and body mass) of Rana zhenhaiensis tadpoles. The results showed that the toxicity levels of the three metallic ions were different when conducted with different experiment designs. For acute toxicity tests, Cu2+ was the most toxic with the highest tadpole mortality. The mortalities of tadpoles showed significant differences among the treatments at the same exposure time endpoints (24, 48, 72 and 96h). Results from repeated measures ANOVA indicated that metallic ion concentration, exposure time and their interactions significantly affected the mortalities of R. zhenhaiensis tadpoles. Also, the toxicity effects of all binary combinations of the three metallic ion treatments showed synergism. The half lethal concentrations (LC50) decreased with increasing exposure time during the experimental period, and the safe concentration (SC)values of Cu2+, Pb2+ and Zn2+ were different from each other. Combined and compared LC50 values with previous data reported, it is suggestes that the toxicity levels of metal pollution to anuran tadpoles should be species-and age-related. For blood biomarker tests, Zn2+ was the most toxic with the highest total frequencies of abnormal erythrocytic nucleus. All three metallic ions caused higher abnormal erythrocytic nucleus compared with control groups. In a chronic toxicity test, Pb2+ was the most toxic with lowest growth traits. Survival rate (except for 18 days), total body length and body mass showed significant differences among the treatments. These findings indicated that tadpoles of R. zhenhaiensis should be as a bioindicator of heavy metals pollution.

  12. Direct trace analysis of metals and alloys in a quadrupole ion-trap mass spectrometer

    Song, K S; Yang, M; Cha, H K; Lee, J M; Lee, G H


    An ion-trap mass spectrometer adopting a quadrupole ion-trap and laser ablation/ionization method was constructed. The developed system was tested for composition analysis of some metals (Cu, stainless), and alloys (hastalloy C, mumetal) by mass spectrometry. Samples were analyzed by using laser ablation from a sample probe tip followed by a mass analysis with the quadrupole ion-trap. The quadrupole ion-trap was modified to enable laser ablation by a XeCl excimer laser pulse that passed radially through the ring electrode. A mass scan of the produced ions was performed in the mass selective instability mode wherein trapped ions were successively detected by increasing the rf voltage through the ring electrode. Factors affecting the mass resolution, such as pressure of buffer gas and ablation laser power, are discussed.

  13. Characterization of low temperature metallic magnetic calorimeters having gold absorbers with implanted $^{163}$Ho ions

    Gastaldo, L; von Seggern, F; Porst, J P; Schäfer, S; Pies, C; Kempf, S; Wolf, T; Fleischmann, A; Enss, C; Herlert, A; Johnston, K


    For the first time we have investigated the behavior of fully micro-fabricated low temperature metallic magnetic calorimeters (MMCs) after undergoing an ion-implantation process. This experiment had the aim to show the possibility to perform a high precision calorimetric measurement of the energy spectrum following the electron capture of $^{163}$Ho using MMCs having the radioactive $^{163}$Ho ions implanted in the absorber. The implantation of $^{163}$Ho ions was performed at ISOLDE-CERN. The performance of a detector that underwent an ion-implantation process is compared to the one of a detector without implanted ions. The results show that the implantation dose of ions used in this experiment does not compromise the properties of the detector. In addition an optimized detector design for future $^{163}$Ho experiments is presented.

  14. Some features of ion mixing during simultaneous ion implantation and deposition of metallic coatings

    Pogrebnyak, A D; Mikhalev, A D; Shablya, V T; Yanovskij, V P


    The results on the Ta, Cu ions implantation into the aluminium substrate by simultaneous deposition of these ions in the form of coatings are presented. The complex structure of these coatings from the given elements in the substrate, as well as the increase in the microhardness, adhesion and corrosion resistance growth are determined. It is shown on the basis of the results of the secondary ions energy distribution, that intermetallic phases are formed in the substrate surface layer

  15. Environmental effects on the structure of metal ion-DOTA complexes: An ab initio study of radiopharmaceutical metals.

    Lau, E Y; Lightstone, F C; Colvin, M E


    Quantum mechanical calculations were performed to study the differences between the important radiopharmaceutical metals yttrium (Y) and indium (In) bound by DOTA and modified DOTA molecules. Energies were calculated at the MP2/6-31+G(d)//HF/6-31G(d) levels, using effective core potentials on the Y and In ions. Although the minimum energy structures obtained are similar for both metal ion-DOTA complexes, changes in coordination and local environment significantly affect the geometries and energies of these complexes. Coordination by a single water molecule causes a change in the coordination number and a change in the position of the metal ion in In-DOTA; but, Y-DOTA is hardly affected by water coordination. When one of the DOTA carboxylates is replaced by an amide, the coordination energy for the amide arm shows a large variation between the Y and In ions. Optimizations including water and guandinium moieties to approximate the effects of antibody binding indicate a large energy cost for the DOTA-chelated In to adopt the ideal conformation for antibody binding.

  16. A Selective Bioreduction of Toxic Heavy Metal Ions from Aquatic Environment by Saccharomyces cerevisiae

    A. M. Rahatgaonkar


    Full Text Available The need to remove or recover metal ions from industrial wastewater has been established in financial as well as environmental terms. This need has been proved financially in terms of cost saving through metal reuse or sale and environmentally as heavy metal toxicity can affect organisms throughout the food chain, including humans. Bioremediation of heavy metal pollution remains a major challenge in environmental biotechnology. Current removal strategies are mainly based on bioreduction of Co++, Ni++, Cu++ and Cd++ to their metallic forms by Saccharomyces cerevisiae in buffered aqueous solution. The rate of biotransformation was significantly influenced by pH of aqueous solution, concentration of biomass and hardness of water. All reaction conditions were optimized and maximum reduction of Co++, Cd++, Ni++ and Cu++ were observed as 80%, 63%, 50%, and 44% respectively. Unreacted Co++, Cd++, Ni++metal ions were extracted by 8-hydroxyquinoline and Cu++ by diethylthio carbamate in CHCl3 at different pH. Furthermore, the concentrations of unreacted metal ions were established spectrophotometrically.

  17. Serum Metal Ion Concentrations in Paediatric Patients following Total Knee Arthroplasty Using Megaprostheses

    Jörg Friesenbichler


    Full Text Available The purpose of this study was to determine the concentrations of cobalt, chromium, and molybdenum in the serum of paediatric tumour patients after fixed hinge total knee arthroplasty. Further, these metal ion levels were compared with serum metal ion levels of patients with other orthopaedic devices such as hip and knee prostheses with metal-on-metal or metal-on-polyethylene articulation to find differences between anatomical locations, abrasion characteristics, and bearing surfaces. After an average follow-up of 108 months (range: 67 to 163 of 11 paediatric patients with fixed hinge total knee arthroplasty, the mean concentrations for Co and Cr were significantly increased while Mo was within the limits compared to the upper values from the reference laboratory. Furthermore, these serum concentrations were significantly higher compared to patients with a standard rotating hinge device (P=0.002 and P<0.001 and preoperative controls (P<0.001. On the other hand, the serum levels of patients following MoM THA or rotating hinge arthroplasty using megaprostheses were higher. Therefore, periodic long-term follow-ups are recommended due to the rising concerns about systemic metal ion exposure in the literature. Upon the occurrence of adverse reactions to metal debris the revision of the fixed hinge implant should be considered.

  18. Responses of a soil bacterium, Pseudomonas chlororaphis O6 to commercial metal oxide nanoparticles compared with responses to metal ions

    Dimkpa, Christian O., E-mail: [Department of Biological Engineering, Utah State University, Logan, UT 84322 (United States); Calder, Alyssa; Britt, David W. [Department of Biological Engineering, Utah State University, Logan, UT 84322 (United States); McLean, Joan E. [Utah Water Research Laboratory, Utah State University, Logan, UT 84322 (United States); Anderson, Anne J. [Department of Biology, Utah State University, Logan, UT 84322 (United States)


    The toxicity of commercially-available CuO and ZnO nanoparticles (NPs) to pathogenic bacteria was compared for a beneficial rhizosphere isolate, Pseudomonas chlororaphis O6. The NPs aggregated, released ions to different extents under the conditions used for bacterial exposure, and associated with bacterial cell surface. Bacterial surface charge was neutralized by NPs, dependent on pH. The CuO NPs were more toxic than the ZnO NPs. The negative surface charge on colloids of extracellular polymeric substances (EPS) was reduced by Cu ions but not by CuO NPs; the EPS protected cells from CuO NPs-toxicity. CuO NPs-toxicity was eliminated by a Cu ion chelator, suggesting that ion release was involved. Neither NPs released alkaline phosphatase from the cells' periplasm, indicating minimal outer membrane damage. Accumulation of intracellular reactive oxygen species was correlated with CuO NPs lethality. Environmental deposition of NPs could create niches for ion release, with impacts on susceptible soil microbes. - Highlights: > Toxicity of metallic nanoparticles (NPs) was evaluated in a beneficial bacterium, Pseudomonas chlororaphis O6 (PcO6). > Aggregated commercial CuO and ZnO NPs released Cu and Zn ions and changed bacterial surface charge, depending on pH. > The NPs were toxic to PcO6 through NP-specific, but also ion release mechanisms. > Reactive oxygen species were produced by CuO NP and Cu ion at lethal concentrations, but bacterial EPS protected against Cu. > The periplasmic marker, alkaline phosphate, activity was increased by the NPs and ions. - Aggregated CuO and ZnO nanoparticles release ions and cause different toxicities in a beneficial soil bacterium.

  19. Preorganized and Immobilized Ligands for Metal Ion Separations

    Paine, Robert T. [Univ. of New Mexico, Albuquerque, NM (United States)


    The research project, in the period 2003-2015, was focused on the discovery of fundamental new principles in f-element ion coordination chemistry and the application of the new knowledge to the development of advanced detection/separations reagents and methods for these ions. The findings relate to the Nation's efforts to safely and efficiently process nuclear materials. In addition, the project provided training for young scientists needed to maintain the Nation's preeminence in nuclear science.

  20. Cyclic peptides-assisted trans- port of metal ions across liquid-organic membrane


    The formation of alkali and alkaline-earth metal picrate complexes with cyclo(Pro-Gly)n ionophores (1, n = 3; 2, n = 4) can facilitate the migration of metal ions across a bulk liquid CH2Cl2 membrane. The migration behavior was studied by measuring the solution absorption at 356 nm, using a UV/Vis spectrophotometer, and the rates can be determined by comparing the initial absorption of donor solutions with the absorption of the corresponding receiver solutions as the function of time. It was found that cyclic peptide 1 shows higher transport activity for the studied alkali and alkaline-earth metal ions than compound 2, which is related to the backbone flexibility of the cyclic peptides. The findings in this work suggest that the rate of ionophore-facilitated ion transport depends not only on the ability of complex forma-tion in aqueous phase, but also on the ability of complex dissociation in organic phase.

  1. Design dopamine-modified polypropylene fibers towards removal of heavy metal ions from water

    K. Liu


    Full Text Available A simple approach to preparing dopamine-modified polypropylene fibers with a controllable polydopamine amount is supplied. By the dopamine modification, the hydrophobic polypropylene fibers have been changed into hydrophilic. The hydrophilicity can be improved by increasing the amount of polydopamine, as revealed by the contact angle evolutions. The hydrophilic dopamine-modified polypropylene fibers can rapidly and effectively remove copper and lead ions in water. Moreover, the performance of removing heavy metals is prominently improved as the polydopamine amount increases. This is because the polydopamine introduction can supply many available sites for adsorbing heavy metal ions, as revealed by theoretical simulation results. These results are crucial in future engineering fiber filters towards efficiently removing heavy metal ions using dopamine-modified polypropylene fibers.

  2. Design dopamine-modified polypropylene fibers towards removal of heavy metal ions from water

    Liu, K.; Zhou, N. Y.; Xie, C. X.; Mou, B.; Ai, Y. N.


    A simple approach to preparing dopamine-modified polypropylene fibers with a controllable polydopamine amount is supplied. By the dopamine modification, the hydrophobic polypropylene fibers have been changed into hydrophilic. The hydrophilicity can be improved by increasing the amount of polydopamine, as revealed by the contact angle evolutions. The hydrophilic dopamine-modified polypropylene fibers can rapidly and effectively remove copper and lead ions in water. Moreover, the performance of removing heavy metals is prominently improved as the polydopamine amount increases. This is because the polydopamine introduction can supply many available sites for adsorbing heavy metal ions, as revealed by theoretical simulation results. These results are crucial in future engineering fiber filters towards efficiently removing heavy metal ions using dopamine-modified polypropylene fibers.

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

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


    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.




    The fractal and multi-fractal patterns of metal atoms are observed in the surface layer and cross section of a metal ion implanted polymer using TEM and SEM for the first time. The surface structure in the metal ion implanted polyethylene terephthalane (PET) is the random fractal. Certain average quantities of the random geometric patterns contain self-similarity. Some growth origins appeared in the fractal pattern which has a dimension of 1.67. The network structure of the fractal patterns is formed in cross section, having a fractal dimension of 1.87. So it can be seen that the fractal pattern is three-dimensional space fractal. We also find the collision cascade fractal in the cross section of implanted nylon, which is similar to the collision cascade pattern in transverse view calculated by the TRIM computer program. Finally, the mechanism for the formation and growth of the fractal patterns during ion implantation is discussed.

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

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


    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.

  6. Effects of impregnated metal ions on air/CO2-gasification of woody biomass.

    Hurley, Scott; Li, Hanning; Xu, Chunbao Charles


    Several impregnated metal ions (Fe (III), Co (II), Ni (II), and Ru (IV)) and a raw iron ore (natural limonite) were examined as catalysts for gasification of pine sawdust in air/CO(2) at 700 and 800 degrees C. The yields of char and tar both increased with increasing CO(2) content in the feed gas. All the impregnated metal ions, in particular Ni (II), Co (II) and Ru (IV), were very effective for promoting biomass gasification in CO(2), leading to greatly reduced yields of tar and char accompanied by significantly enhanced formation of CO and H(2). At 800 degrees C, the impregnation of Fe (III), Ni (II), Co (II) or Ru (IV) led to almost complete conversion of the solid biomass into gas/liquid products, producing an extremely low char yield (tar yield reduced from 32.1 wt.% without catalyst to 19-27 wt.% with the impregnated metal ions.

  7. Luminescent, freestanding composite films of Au15 for specific metal ion sensing.

    George, Anu; Shibu, E S; Maliyekkal, Shihabudheen M; Bootharaju, M S; Pradeep, T


    A highly luminescent freestanding film composed of the quantum cluster, Au(15), was prepared. We studied the utility of the material for specific metal ion detection. The sensitivity of the red emission of the cluster in the composite to Cu(2+) has been used to make a freestanding metal ion sensor, similar to pH paper. The luminescence of the film was stable when exposed to several other metal ions such as Hg(2+), As(3+), and As(5+). The composite film exhibited visual sensitivity to Cu(2+) up to 1 ppm, which is below the permissible limit (1.3 ppm) in drinking water set by the U.S. environmental protection agency (EPA). The specificity of the film for Cu(2+) sensing may be due to the reduction of Cu(2+) to Cu(1+)/Cu(0) by the glutathione ligand or the Au(15) core. Extended stability of the luminescence of the film makes it useful for practical applications.

  8. Cubic nitrides of the sixth group of transition metals formed by nitrogen ion irradiation during metal condensation

    Ensinger, W. [Augsburg Univ. (Germany). Inst. fuer Physik; Kiuchi, M. [Osaka National Research Institute, Midorigaoka 1-8-31, Ikeda, Osaka 563 (Japan)


    Nitrogen-containing phases of chromium, molybdenum and tungsten were formed by evaporation of the metal under simultaneous nitrogen ion irradiation. With gradually increasing ion irradiation intensity, chromium forms initially Cr and Cr{sub 2}N phase mixtures, then additionally CrN appears, and at the highest intensities pure CrN films are formed. Molybdenum also forms pure nitride MoN under intense ion bombardment. However, in this case two different crystal structures are found, the stable hexagonal phase and the metastable cubic high-temperature phase. The latter is favoured under intense ion irradiation. In the case of tungsten, even at the highest intensities, only phase mixtures of W and W{sub 2}N were formed. These observed differences can be explained by the low reactivity of these metals towards nitrogen and the low chemical stability of the nitrides, particularly of WN. The metastable high-temperature structure of MoN is formed under the particular conditions of ion bombardment with rapid energy dissipation. (orig.)

  9. Sample metallization for performance improvement in desorption/ionization of kilodalton molecules: quantitative evaluation, imaging secondary ion MS, and laser ablation.

    Delcorte, A; Bour, J; Aubriet, F; Muller, J-F; Bertrand, P


    The metallization procedure, proposed recently for signal improvement in organic secondary ion mass spectrometry (SIMS) (Delcorte, A.; Médard, N.; Bertrand, P. Anal.Chem. 2002, 74, 4955)., has been thoroughly tested for a set of kilodalton molecules bearing various functional groups: Irganox 1010, polystyrene, polyalanine, and copper phthalocyanine. In addition to gold, we evaluate the effect of silver evaporation as a sample treatment prior to static SIMS analysis. Ion yields, damage cross sections, and emission efficiencies are compared for Ag- and Au-metallized molecular films, pristine coatings on silicon, and submonolayers of the same molecules adsorbed on silver and gold. The results are sample-dependent but as an example, the yield enhancement calculated for metallized Irganox films with respect to untreated coatings is larger than 2 orders of magnitude for the quasimolecular ion and a factor of 1-10 for characteristic fragments. Insights into the emission processes of quasimolecular ions from metallized surfaces are deduced from kinetic energy distribution measurements. The advantage of the method for imaging SIMS applications is illustrated by the study of a nonuniform coating of polystyrene oligomers on a 100-microm polypropylene film. The evaporated metal eliminates sample charging and allows us to obtain enhanced quality images of characteristic fragment ions as well as reasonably contrasted chemical mappings for cationized PS oligomers and large PP chain segments. Finally, we report on the benefit of using metal evaporation as a sample preparation procedure for laser ablation mass spectrometry. Our results show that the fingerprint spectra of Au-covered polystyrene, polypropylene, and Irganox films can be readily obtained under 337-nm irradiation, a wavelength for which the absorption of polyolefins is low. This is probably because the gold clusters embedded in the sample surface absorb and transfer the photon energy to the surrounding organic medium.

  10. Study on the adsorption of heavy metal ions from aqueous solution on modified SBA-15

    Liliana Giraldo


    Full Text Available Amino-functionalized SBA-15 mesoporous silica was prepared, characterized, and used as an adsorbent for heavy metal ions. The organic - inorganic hybrid material was obtained by a grafting procedure using SBA-15 silica with 3-aminopropyl-triethoxysilane and bis(2,4,4-trimethylpentyl phosphinic acid (Cyanex 272, respectively. The structure and physicochemical properties of the materials were characterized by means of elemental analysis, X-ray diffraction (XRD, nitrogen adsorption - desorption, thermogravimetric analysis, FTIR spectroscopy and immersion calorimetry. The organic functional groups were successfully grafted onto the SBA-15 surface and the ordering of the support was not affected by the chemical modification. The behavior of the grafted solids was investigated for the adsorption of heavy metal ions from aqueous solutions. The hybrid materials showed high adsorption capacity and high selectivity for zinc ions. Other ions, such as cooper and cobalt were absorbed by the modified SBA-15 material.

  11. Metal Ion Activation of Clostridium sordellii Lethal Toxin and Clostridium difficile Toxin B

    Harald Genth


    Full Text Available Lethal Toxin from Clostridium sordellii (TcsL and Toxin B from Clostridium difficile (TcdB belong to the family of the “Large clostridial glycosylating toxins.” These toxins mono-O-glucosylate low molecular weight GTPases of the Rho and Ras families by exploiting UDP-glucose as a hexose donor. TcsL is casually involved in the toxic shock syndrome and the gas gangrene. TcdB—together with Toxin A (TcdA—is causative for the pseudomembranous colitis (PMC. Here, we present evidence for the in vitro metal ion activation of the glucosyltransferase and the UDP-glucose hydrolysis activity of TcsL and TcdB. The following rating is found for activation by divalent metal ions: Mn2+ > Co2+ > Mg2+ >> Ca2+, Cu2+, Zn2+. TcsL and TcdB thus require divalent metal ions providing an octahedral coordination sphere. The EC50 values for TcsL were estimated at about 28 µM for Mn2+ and 180 µM for Mg2+. TcsL and TcdB further require co-stimulation by monovalent K+ (not by Na+. Finally, prebound divalent metal ions were dispensible for the cytopathic effects of TcsL and TcdB, leading to the conclusion that TcsL and TcdB recruit intracellular metal ions for activation of the glucosyltransferase activity. With regard to the intracellular metal ion concentrations, TcsL and TcdB are most likely activated by K+ and Mg2+ (rather than Mn2+ in mammalian target cells.

  12. Shot-to-shot reproducibility in the emission of fast highly charged metal ions from a laser ion source.

    Krása, J; Velyhan, A; Margarone, D; Krouský, E; Krouský, L; Jungwirth, K; Rohlena, K; Ullschmied, J; Parys, P; Ryć, L; Wołowski, J


    The generation of fast highly charged metal ions with the use of the sub-nanosecond Prague Asterix Laser System, operated at a fundamental wavelength of 1315 nm, is reported. Particular attention is paid to shot-to-shot reproducibility in the ion emission. Au and Pd targets were exposed to intensities up to 5 × 10(16) W∕cm(2). Above the laser intensity threshold of ∼3 × 10(14) W∕cm(2) the plasma is generated in a form of irregular bursts. The maximum energy of protons constituting the leading edge of the fastest burst reaches a value up to 1 MeV. The fast ions in the following bursts have energy gradually decreasing with the increasing burst number, namely, from a value of about 0.5 MeV∕charge regardless of the atomic number and mass of the ionized species.

  13. Construction and evaluation of a metal ion biosensor

    Tescione, Lia; Belfort, Georges


    E. coli, genetically engineered with a mercury(II)-sensitive promoter and the lux genes from Vibrio fischeri, were used as microbial sensors for the detection of mercury. Evaluation of this genetic construction was carried out by determining the effects of various parameters on cell suspensions maintained at constant conditions in a small vessel. The strongest light intensities and quickest induction times occurred with cells in the mid-exponential growth phase maintained at 280 C, concentrated to 1 x 10(exp 9) cells/mL, mixed at very fast speeds, and aerated at 2 vvm (volume of air per volume of culture per minute) during light measurement in the small vessel. The sensitivity of these cells to the mercuric ion lied in the range of 0.02-4 micrometer (4-800 ppb) and the total response time was on the order of one hour, depending on the above parameters. The cells exhibited great specificity for mercury. The cells have almost equal specificity for organic and inorganic form of the mercuric ion and responded more weakly to the mercurous ion. A simple, inexpensive, durable miniature probe was constructed and operated using the optimum parameters found in the small vessel as a guide. The range of sensitivity to the mercuric ion detected in the probe was 0.01-4 micrometer when aeration was provided.

  14. Metal Ion Dependence of Cooperative Collapse Transitions in RNA

    Moghaddam, Sarvin; Caliskan, Gokhan; Chauhan, Seema; Hyeon, Changbong; Briber, R.M.; Thirumalai, D.; Woodson, Sarah A.; (Chung-Ang); (JHU); (Maryland)


    Positively charged counterions drive RNA molecules into compact configurations that lead to their biologically active structures. To understand how the valence and size of the cations influences the collapse transition in RNA, small-angle X-ray scattering was used to follow the decrease in the radius of gyration (R{sub g}) of the Azoarcus and Tetrahymena ribozymes in different cations. Small, multivalent cations induced the collapse of both ribozymes more efficiently than did monovalent ions. Thus, the cooperativity of the collapse transition depends on the counterion charge density. Singular value decomposition of the scattering curves showed that folding of the smaller and more thermostable Azoarcus ribozyme is well described by two components, whereas collapse of the larger Tetrahymena ribozyme involves at least one intermediate. The ion-dependent persistence length, extracted from the distance distribution of the scattering vectors, shows that the Azoarcus ribozyme is less flexible at the midpoint of transition in low-charge-density ions than in high-charge-density ions. We conclude that the formation of sequence-specific tertiary interactions in the Azoarcus ribozyme overlaps with neutralization of the phosphate charge, while tertiary folding of the Tetrahymena ribozyme requires additional counterions. Thus, the stability of the RNA structure determines its sensitivity to the valence and size of the counterions.

  15. Dense Metal Plasma in a Solenoid for Ion Beam Neutralization

    Anders, Andre; Kauffeldt, Marina; Oks, Efim M.; Roy, Prabir K.


    Space-charge neutralization is required to compress and focus a pulsed, high-current ion beam on a target for warm dense matter physics or heavy ion fusion experiments. We described approaches to produce dense plasma in and near the final focusing solenoid through which the ion beam travels, thereby providing an opportunity for the beam to acquire the necessary space-charge compensating electrons. Among the options are plasma injection from pulsed vacuum arc sources located outside the solenoid, and using a high current (> 4 kA) pulsed vacuum arc plasma from a ring cathode near the edge of the solenoid. The plasma distribution is characterized by photographic means, by an array of movable Langmuir probes, by a small single probe, and by evaluating Stark broadening of the Balmer H beta spectral line. In the main approach described here, the plasma is produced at several cathode spots distributed azimuthally on the ring cathode. It is shown that the plasma is essentially hollow, as determined by the structure of the magnetic field, though the plasma density exceeds 1014 cm-3 in practically all zones of the solenoid volume if the ring electrode is placed a few centimeters off the center of the solenoid. The plasma is non-uniform and fluctuating, however, since its density exceeds the ion beam density it is believed that this approach could provide a practical solution to the space charge neutralization challenge.

  16. Using Metal Complex Ion-Molecule Reactions in a Miniature Rectilinear Ion Trap Mass Spectrometer to Detect Chemical Warfare Agents

    Graichen, Adam M.; Vachet, Richard W.


    The gas-phase reactions of a series of coordinatively unsaturated [Ni(L)n]y+ complexes, where L is a nitrogen-containing ligand, with chemical warfare agent (CWA) simulants in a miniature rectilinear ion trap mass spectrometer were investigated as part of a new approach to detect CWAs. Results show that upon entering the vacuum system via a poly(dimethylsiloxane) (PDMS) membrane introduction, low concentrations of several CWA simulants, including dipropyl sulfide (simulant for mustard gas), acetonitrile (simulant for the nerve agent tabun), and diethyl phosphite (simulant for nerve agents sarin, soman, tabun, and VX), can react with metal complex ions generated by electrospray ionization (ESI), thereby providing a sensitive means of detecting these compounds. The [Ni(L)n]2+ complexes are found to be particularly reactive with the simulants of mustard gas and tabun, allowing their detection at low parts-per-billion (ppb) levels. These detection limits are well below reported exposure limits for these CWAs, which indicates the applicability of this new approach, and are about two orders of magnitude lower than electron ionization detection limits on the same mass spectrometer. The use of coordinatively unsaturated metal complexes as reagent ions offers the possibility of further tuning the ion-molecule chemistry so that desired compounds can be detected selectively or at even lower concentrations.

  17. Negative ion photoelectron spectroscopic studies of transition metal cluster

    Marcy, Timothy Paul

    The studies reported in this thesis were performed using a negative ion photoelectron spectrometer consisting of a cold cathode DC discharge ion source, a flowing afterglow ion-molecule reactor, a magnetic sector mass analyzer, an argon ion laser for photodetachment and a hemispherical electron kinetic energy analyzer and microchannel plate detector for photoelectron spectrum generation. The 476.5 nm (2.601 eV), 488.0 nm (2.540 eV) and 514.5 nm (2.410 eV) negative ion photoelectron spectra of VMn are reported and compared to the previously studied spectra of isoelectronic Cr2.1 The photoelectron spectra are remarkably similar to those of Cr2 in electron affinity and vibrational frequencies. The 488.0 nm photoelectron spectra and electron affinities of Nb n- (n = 1 - 9) are reported with discussion of observed vibrational structure. There are transitions to several electronic states of Nb2 in the reported spectra with overlapping vibrational progressions. The spectra of Nb3, Nb4 and Nb6 show partially resolved vibrational structure in the transitions to the lowest observed electronic state of each cluster. There is a single distinct active vibrational mode in the transition to the ground state of Nb8. Spin-orbit energies of Nb- are also reported. The 488.0 nm negative ion photoelectron spectra of Nb3H(D) are reported and compared to those of Nb3. There is a single vibrational mode active in the spectra of Nb3H(D) which is very similar to the most distinct mode active in the spectrum of Nb3. The 488.0 nm photoelectron spectra of the NbxCyH(D) y- (x = 1, 2, 3, y = 2, 4, 6) dehydrogenated products of the reactions of ethylene with niobium cluster anions are reported. Temperature studies of some of these species give evidence for the presence of multiple isomers of each molecule in the ion beam. The spectra of NbC6H(D) 6 are identical to those obtained from the reactions of benzene with niobium clusters and indicate that benzene is being formed from ethylene in the flow

  18. Dynamics of low- and high-Z metal ions emitted during nanosecond laser-produced plasmas

    Elsied, Ahmed M.; Diwakar, Prasoon K.; Polek, Mathew; Hassanein, Ahmed


    Dynamics of metal ions during laser-produced plasmas was studied. A 1064 nm, Nd: YAG laser pulse was used to ablate pure Al, Fe, Co, Mo, and Sn samples. Ion flux and velocity were measured using Faraday cup ion collector. Time-of-flight measurements showed decreasing ion flux and ion velocity with increasing atomic weight, and heavy metal ion flux profile exhibited multiple peaks that was not observed in lighter metals. Slow peak was found to follow shifted Maxwell Boltzmann distribution, while the fast peak was found to follow Gaussian distribution. Ion flux angular distribution that was carried out on Mo and Al using fixed laser intensity 2.5 × 1010 W/cm2 revealed that the slow ion flux peaks at small angles, that is, close to normal to the target ˜0° independent of target's atomic weight, and fast ion flux for Mo peaks at large angles ˜40° measured from the target normal, while it completely absents for Al. This difference in spatial and temporal distribution reveals that the emission mechanism of the fast and slow ions is different. From the slow ion flux angular distribution, the measured plume expansion ratio (plume forward peaking) was 1.90 and 2.10 for Al and Mo, respectively. Moreover, the effect of incident laser intensity on the ion flux emission as well as the emitted ion velocity were investigated using laser intensities varying from 2.5 × 1010 W/cm2 to 1.0 × 1011 W/cm2. Linear increase of fast ion flux and velocity, and quadratic increase of slow ion flux and velocity were observed. For further understanding of plume dynamics, laser optical emission spectroscopy was used to characterize Sn plasma by measuring the temporal and spatial evolution of plasma electron density Ne and electron temperature Te. At 3.5 mm away from the target, plasma density showed slow decrease with time, however electron temperature was observed to decrease dramatically. The maximum plasma density and temperature occurred at 0.5 mm away from target and were measured to

  19. Chelation gradients for investigation of metal ion binding at silica surfaces.

    Kannan, Balamurali; Higgins, Daniel A; Collinson, Maryanne M


    Centimeter-long surface gradients in bi- and tridentate chelating agents have been formed via controlled rate infusion, and the coordination of Cu(2+) and Zn(2+) to these surfaces has been examined as a function of distance by X-ray photoelectron spectroscopy (XPS). 3-(Trimethoxysilylpropyl)ethylenediamine and 3-(trimethoxysilylpropyl)diethylenetriamine were used as precursor silanes to form the chelation gradients. When the gradients were exposed to a metal ion solution, a series of coordination complexes formed along the length of the substrate. For both chelating agents at the three different concentrations studied, the amine content gradually increased from top to bottom as expected for a surface chemical gradient. While the Cu 2p peak area had nearly the same profile as nitrogen, the Zn 2p peak area did not and exhibited a plateau along much of the gradient. The normalized nitrogen-to-metal peak area ratio (N/M) was found to be highly dependent on the type of ligand, its surface concentration, and the type of metal ion. For Cu(2+), the N/M ratio ranged from 8 to 11 on the diamine gradient and was ∼4 on the triamine gradient, while for Zn(2+), the N/M ratio was 4-8 on diamine and 5-7 on triamine gradients. The extent of protonation of amine groups was higher for the diamine gradients, which could lead to an increased N/M ratio. Both 1:1 and 1:2 ligand/metal complexes along with dinuclear complexes are proposed to form, with their relative amounts dependent on the ligand, ligand density, and metal ion. Collectively, the methods and results described herein represent a new approach to study metal ion binding and coordination on surfaces, which is especially important to the extraction, preconcentration, and separation of metal ions.

  20. Natural Jordanian zeolite: removal of heavy metal ions from water samples using column and batch methods.

    Baker, Hutaf M; Massadeh, Adnan M; Younes, Hammad A


    The adsorption behavior of natural Jordanian zeolites with respect to Cd(2 + ), Cu(2 + ), Pb(2 + ), and Zn(2 + ) was studied in order to consider its application to purity metal finishing drinking and waste water samples under different conditions such as zeolite particle size, ionic strength and initial metal ion concentration. In the present work, a new method was developed to remove the heavy metal by using a glass column as the one that used in column chromatography and to make a comparative between the batch experiment and column experiment by using natural Jordanian zeolite as adsorbent and some heavy metals as adsorbate. The column method was used using different metal ions concentrations ranged from 5 to 20 mg/L with average particle size of zeolite ranged between 90 and 350 mum, and ionic strength ranged from 0.01 to 0.05. Atomic absorption spectrometry was used for analysis of these heavy metal ions, the results obtained in this study indicated that zeolitic tuff is an efficient ion exchanger for removing heavy metals, in particular the fine particle sizes of zeolite at pH 6, whereas, no clear effect of low ionic strength values is noticed on the removal process. Equilibrium modeling of the removal showed that the adsorption of Cd(2 + ), Cu(2 + ), Pb(2 + ), and Zn(2 + ) were fitted to Langmuir, Freundlich and Dubinin-Kaganer-Radushkevich (DKR). The sorption energy E determined in the DKR equation (9.129, 10.000, 10.541, and 11.180 kJ/mol for Zn(2 + ), Cu(2 + ), Cd(2 + ) and Pb(2 + ) respectively) which revealed the nature of the ion-exchange mechanism.

  1. Contiguous metal-mediated base pairs comprising two Ag(I) ions.

    Megger, Dominik A; Guerra, Célia Fonseca; Hoffmann, Jan; Brutschy, Bernhard; Bickelhaupt, F Matthias; Müller, Jens


    The incorporation of transition-metal ions into nucleic acids by using metal-mediated base pairs has proved to be a promising strategy for the site-specific functionalization of these biomolecules. We report herein the formation of Ag(+)-mediated Hoogsteen-type base pairs comprising 1,3-dideaza-2'-deoxyadenosine and thymidine. By defunctionalizing the Watson-Crick edge of adenine, the formation of regular base pairs is prohibited. The additional substitution of the N3 nitrogen atom of adenine by a methine moiety increases the basicity of the exocyclic amino group. Hence, 1,3-dideazaadenine and thymine are able to incorporate two Ag(+) ions into their Hoogsteen-type base pair (as compared with one Ag(+) ion in base pairs with 1-deazaadenine and thymine). We show by using a combination of experimental techniques (UV and circular dichroism (CD) spectroscopies, dynamic light scattering, and mass spectrometry) that this type of base pair is compatible with different sequence contexts and can be used contiguously in DNA double helices. The most stable duplexes were observed when using a sequence containing alternating purine and pyrimidine nucleosides. Dispersion-corrected density functional theory calculations have been performed to provide insight into the structure, formation and stabilization of the twofold metalated base pair. They revealed that the metal ions within a base pair are separated by an Ag···Ag distance of about 2.88 Å. The Ag-Ag interaction contributes some 16 kcal mol(-1) to the overall stability of the doubly metal-mediated base pair, with the dominant contribution to the Ag-Ag bonding resulting from a donor-acceptor interaction between silver 4d-type and 4s orbitals. These Hoogsteen-type base pairs enable a higher functionalization of nucleic acids with metal ions than previously reported metal-mediated base pairs, thereby increasing the potential of DNA-based nanotechnology.

  2. Metal ions to control the morphology of semiconductor nanoparticles: copper selenide nanocubes.

    Li, Wenhua; Zamani, Reza; Ibáñez, Maria; Cadavid, Doris; Shavel, Alexey; Morante, Joan Ramon; Arbiol, Jordi; Cabot, Andreu


    Morphology is a key parameter in the design of novel nanocrystals and nanomaterials with controlled functional properties. Here, we demonstrate the potential of foreign metal ions to tune the morphology of colloidal semiconductor nanoparticles. We illustrate the underlying mechanism by preparing copper selenide nanocubes in the presence of Al ions. We further characterize the plasmonic properties of the obtained nanocrystals and demonstrate their potential as a platform to produce cubic nanoparticles with different composition by cation exchange.

  3. Development of physical fundamentals and computer design of technology of ion implantation of metals

    Kolobov, Yu.P.; Sharkeev, Yu.P.; Abdrashitov, V.G.; Kashin, O.A


    The unique possibilities of controlled modification of the chemical composition, structure and properties of thin surface films of metals and alloys are offered by the method of high-dose ion implantation (Hll). Modification of the surface of materials by ion implantation has been used on an increasing scale as an industrial technology of ensuring a large increase of the service life of components and tools. It is urgent to investigate the physical fundamentals of this promising technology.

  4. Streptococcus mutans adhesion and releasing of metallic ions in dental alloys

    Zavanelli,Adriana Cristina; Zavanelli, Ricardo Alexandre; Mazaro, José Vitor Quinelli [UNESP; Falcón-Antenucci,Rosse Mary


    AIM: To evaluate the adherence of Streptococcus mutans to the surface of the amalgam and copper/aluminum alloy samples and also evaluate the release of metallic ions. METHODS: The prepared medium was changed every 72 h and analyzed by atomic absorption spectrophotometer. Samples were removed from the prepared medium at 15, 30, 48 and 60 days. RESULTS: The result shows that ions released were statistically different among all groups, and so were both biofilm and pits formation and the corrosio...

  5. Multiheteromacrocycles that Complex Metal Ions. Ninth Progress Report (includes results of last three years), 1 May 1980 -- 30 April 1983

    Cram, D. J.


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

  6. Exhaustive removal of chloride ions from water with the aid of a bismuth-based metallic sorbent

    Moskvin, L.N.; Ushenko, V.G.


    The authors discuss the sorption properties of sorbents based on metallic bismuth, in relation to a solution of the problem of exhaustive removal of chloride ions from water. Metallic sorbents with bismuth contents of 10 mass % on polytetrafluoroethylene were used. The sorption properties of sorbents based on metallic bismuth and on Bi/sub 2/O/sub 3/ were studied under dynamic conditions. Their results show that bismuth-based metal sorbents and sorbents based on bismuth oxide can be used as inorganic anion-exchangers. In order to demonstrate the possibility of selective separation of chloride ions from solutions they determined the dynamic exchange capacity for chloride ions at various nitrate-ion concentrations. The use of the proposed sorbents based on metallic bismuth for exhaustive purification of water lowers the chloride-ion concentration in the water sharply in comparison with the level achieved by ion-exchange purification with the aid of organic anion-exchangers.

  7. pH- and Metal Ion- Sensitive Hydrogels based on N-[2-(dimethylaminoethylacrylamide

    Leena Nebhani


    Full Text Available Smart hydrogels are promising materials for actuators and sensors, as they can respond to small changes in their environment with a large property change. Hydrogels can respond to a variety of stimuli, for example temperature, pH, metal ions, etc. In this article, the synthesis and characterization of polyampholyte hydrogels based on open chain ligands showing pH and metal ion sensitivity are described. Copolymer and terpolymer gels using different mixtures of monomers i.e., N-[2-(dimethylaminoethylacrylamide] (DMAEAAm, N,N-dimethylacrylamide (DMAAm, acrylic acid (AA and 2-acrylamido-2-methyl-1-propanesulphonic acid (AMPS, have been synthesized. The effect of copolymer composition, i.e., the ratio and amount of ionic monomers and the degree of crosslinking on the swelling characteristics, was evaluated as a function of pH. On this basis, metal ion sensitivity measurements were performed at selected pH values. The metal ion sensitivity was measured by varying the concentration of Cu2+, Zn2+ and Ag+ ions under acidic pH conditions.

  8. Computer simulations of aqua metal ions for accurate reproduction of hydration free energies and structures

    Li, Xin; Tu, Yaoquan; Tian, He; Ågren, Hans


    Metal ions play essential roles in biological processes and have attracted much attention in both experimental and theoretical fields. By using the molecular dynamics simulation technology, we here present a fitting-refining procedure for deriving Lennard-Jones parameters of aqua metal ions toward the ultimate goal of accurately reproducing the experimentally observed hydration free energies and structures. The polarizable SWM4-DP water model {proposed by Lamoureux et al. [J. Chem. Phys. 119, 5185 (2003)]} is used to properly describe the polarization effects of water molecules that interact with the ions. The Lennard-Jones parameters of the metal ions are first obtained by fitting the quantum mechanical potential energies of the hexahydrated complex and are subsequently refined through comparison between the calculated and experimentally measured hydration free energies and structures. In general, the derived Lennard-Jones parameters for the metal ions are found to reproduce hydration free energies accurately and to predict hydration structures that are in good agreement with experimental observations. Dynamical properties are also well reproduced by the derived Lennard-Jones parameters.

  9. Effects of site substitution and metal ion addition on doped manganites

    Pradhan, A K; Roul, B K; Sahu, D R; Muralidhar, M


    We report transport, magnetization and transmission electron microscopy studies of the effects of A-and B-site substitution, and the addition of metal ions such as Pt, Ag and Sr, on doped ABO sub 3 perovskites, where A = La, Pr etc and B = Mn. Disorder induced by such substitution changes the behaviour of the charge-ordered (CO) state significantly. A-and B-site substitution suppresses the CO phase due to size mismatch and disorder produced by inhomogeneity. On the other hand, addition of metal ions such as Pt and Ag improves several colossal-magnetoresistance properties significantly due to microstructural effects and enhanced current percolation through grain boundaries.

  10. Adsorption of graphene oxide/chitosan porous materials for metal ions

    Yong Qiang He; Na Na Zhang; Xiao Dong Wang


    Porous graphene oxide/chitosan (PGOC) materials were prepared by a unidirectional freeze-drying method. Their porous structure, mechanical property and adsorption for metal ions were investigated. The results show that the incorporation of graphene oxide (GO) significantly increased the compressive strength of the PGOC materials. The saturated adsorption capacity of Pb2+ increased about 31%, up to 99 mg/g when 5 wt% GO was incorporated These biodegradable, nontoxic, efficient PGOC materials will be a potential adsorbent for metal ions in aqueous solution.

  11. Mechanistic studies of metal ion binding to water-soluble polymers using potentiometry.

    Jarvis, N V; Wagener, J M


    A method for elucidating metal ion binding mechanisms with water-soluble polymers has been developed in which the polymer is treated as a collection of monomeric units. Data obtained from potentiometric titrations are analysed by the ESTA library of programs and apparent formation constants may be calculated. From this information, predictions may be made as to metal ion separation using complexation-ultrafiltration techniques. The polymer used in this study was Polymin Water-Free and its complexation with Hg(II), Cd(II), Pb(II), Co(II) and Ni(II) was successfully modelled.

  12. Ion dynamics in laser ablation plumes from selected metals at 355 nm

    Thestrup Nielsen, Birgitte; Christensen, Bo Toftmann; Schou, Jørgen


    The dynamics of ions in a laser ablation plume from a number of metals irradiated by a ns-second pulse at 355 nm has been studied. The time-of-flight signals peak at flight times corresponding to velocities between 30 and 10 km/s with decreasing values for increasing atomic masses. The angular...... distributions of the integrated ion signals are strongly peaked in forward direction, and the values for the volatile Bi are somewhat higher than those for the other metals. The distributions have been analyzed on the basis of Anisimov's expansion model. The fraction of ionized atoms can be estimated from...

  13. Characterization and use of Moringa oleifera seeds as biosorbent for removing metal ions from aqueous effluents.

    Araújo, Cleide S T; Alves, Vanessa N; Rezende, Hélen C; Almeida, Ione L S; de Assunção, Rosana M N; Tarley, César R T; Segatelli, Mariana G; Coelho, Nivia M Melo


    Moringa oleifera seeds were investigated as a biosorbent for removing metal ions from aqueous effluents. The morphological characteristics as well as the chemical composition of M. oleifera seeds were evaluated using Fourier Transform Infrared (FT-IR) Spectroscopy, Thermogravimetric Analysis (TGA), X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The FT-IR spectra showed the presence of lipids and protein components. Scanning electron micrographs showed that Moringa seeds have an adequate morphological profile for the retention of metal ions. The results suggest that M. oleifera seeds have potential application in Cd(II), Pb(II), Co(II), Cu(II) and Ag(I) decontamination from aqueous effluents.

  14. De novo design of peptide scaffolds as novel preorganized ligands for metal-ion coordination.

    Gamble, Aimee J; Peacock, Anna F A


    This chapter describes how de novo designed peptides can be used as novel preorganized ligands for metal ion coordination. The focus is on the design of peptides which are programmed to spontaneously self-assemble into α-helical coiled coils in aqueous solution, and how metal ion binding sites can be engineered onto and into these structures. In addition to describing the various design principles, some key examples are covered illustrating the success of this approach, including a more detailed example in the case study.

  15. [Activation of lipid peroxidation in the adrenal cortex by metal ions].

    Doroshkevich, N A; Antsulevich, S N; Vinogradov, V V


    The processes of lipid peroxidation have been studied in bovine adrenal cortex in vitro. The lipid peroxidation rate in this tissue is shown to be dependent on the content of metal ions. EDTA, deferroxamine and penicyllamine inhibit spontaneous lipid peroxidation by 25, 50 and 42%, respectively. The ability to activate the process permits arranging metal ions in the following sequence: Fe2+ greater than Fe3+ greater than Cu2+ greater than Mg2+ greater than Mn2+. The maximum activation of lipid peroxidation is observed at Fe2+ and Fe3+ concentrations within the range of 5 x 10(-6) x 10(-4) M.

  16. Removal of heavy metal ions from water by complexation-assisted ultrafiltration.

    Trivunac, Katarina; Stevanovic, Slavica


    Toxic heavy metals in air, soil and water are global problems that are growing threat to the environment. Therefore, the removal and separation of toxic and environmentally relevant heavy metal ions are a technological challenge with respect to industrial and environmental application. A promising process for the removal of heavy metal ions from aqueous solutions involves bonding the metals to a bonding agent (such as macromolecular species), and then separating the loaded agents from wastewater by separation processes such as membrane filtration. The choice of water-soluble macroligands remains important for developing this technology. The effects of type of complexing agent, pH value and applied pressure on retention coefficients of Zn(II) and Cd(II) complexes were investigated. At best operating conditions (pH=9.0, p=300kPa) using diethylaminoethyl cellulose, the removal of Cd(2+) and Zn(2+) was more than 95% and 99%, respectively.

  17. Assembly of nanoions via electrostatic interactions: ion-like behavior of charged noble metal nanoclusters.

    Yao, Qiaofeng; Luo, Zhentao; Yuan, Xun; Yu, Yue; Zhang, Chao; Xie, Jianping; Lee, Jim Yang


    The assembly of ultrasmall metal nanoclusters (NCs) is of interest to both basic and applied research as it facilitates the determination of cluster structures and the customization of cluster physicochemical properties. Here we present a facile and general approach to assemble noble metal NCs by selectively inducing electrostatic interactions between negatively-charged metal NCs and divalent cations. The charged metal NCs, which have well-defined sizes, charges and structures; and behave similarly to multivalent anions, can be considered as nanoions. These nanoions exhibit step-like assembly behavior when interacting with the counter cations - assembly only occurs when the solubility product (Ksp) between the carboxylate ions on the NC surface and the divalent cations is exceeded. The assembly here is distinctively different from the random aggregation of colloidal particles by counter ions. The nanoions would assemble into fractal-like monodisperse spherical particles with a high order of regularity that mimic the assembly of ionic crystals.

  18. a Comprehensive Model of Global Transport and Localized Layering of Metallic Ions in the Upper Atmosphere.

    Carter, Leonard Nelson, Jr.


    The physics and chemistry of atmospheric metallic ions have been an active area of research for many years; however, a number of issues remain unresolved. Numerical models have been developed and used to establish and validate theories of metallic ion dynamics. While agreement with observational measurements has generally been satisfactory, these models have embodied highly simplified pictures of the total physical system, usually focusing on a single aspect of metallic dynamics. The model described herein is considered the first to simulate all phases of the life cycle of metallic ions. This cycle begins with the initial deposition of metallics through meteor ablation and sputtering, followed by conversion of neutral atoms to ions through photoionization and charge exchange with ambient ions. Global ion transport arising from daytime electric fields and poleward/downward diffusion along geomagnetic field lines, localized transport and layer formation through descending convergent nulls in the thermospheric tidal wind field, and finally annihilation by chemical neutralization and compound formation are treated. The end result of this developmental effort is a model that has not only shown good agreement with observations, but has also shed new light on the interdependencies of the physical and chemical processes affecting atmospheric metallics. The model has been used, in both one- and two -dimensional versions, to simulate ion dynamics in the vertical dimension (at Arecibo, PR, 19^circ N, 67^circW), and in the vertical and meridional dimensions from the equator to 45^circN, ranging over a 90 to 4000 km altitude span. Model output analysis confirms the dominant role of both global and local transport to the ions' life cycle, showing that upward forcing from the equatorial electric field is critical to global movement, and that diurnal and semidiurnal tidal winds are responsible for the formation of dense ion layers in the 90-150 km height region. The model also

  19. Potentiometric and spectroscopic study of the interaction of 3d transition metal ions with inositol hexakisphosphate

    Veiga, Nicolás; Macho, Israel; Gómez, Kerman; González, Gabriel; Kremer, Carlos; Torres, Julia


    Among myo-inositol phosphates, the most abundant in nature is the myo-inositol hexakisphosphate, InsP6. Although it is known to be vital to cell functioning, the biochemical research into its metabolism needs chemical and structural analysis of all the protonation, complexation and precipitation processes that it undergoes in the biological media. In view of its high negative charge at physiological level, our group has been leading a thorough research into the InsP6 chemical and structural behavior in the presence of the alkali and alkaline earth metal ions essential for life. The aim of this article is to extend these studies, dealing with the chemical and structural features of the InsP6 interaction with biologically relevant 3d transition metal ions (Fe(II), Fe(III), Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)), in a non-interacting medium and under simulated physiological conditions. The metal-complex stability constants were determined by potentiometry, showing under ligand-excess conditions the formation of mononuclear species in different protonation states. Under metal ion excess, polymetallic species were detected for Fe(II), Fe(III), Zn(II) and Cu(II). Additionally, the 31P NMR and UV-vis spectroscopic studies provided interesting structural aspects of the strong metal ion-InsP6 interaction.

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

    D' Aquino,J.; Tetenbaum-Novatt, J.; White, A.; Berkovitch, F.; Ringe, D.


    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. Calorimetric techniques have demonstrated that although binding site 1 (ancillary) has high affinity for metal ion with a binding constant of 2 x 10{sup -7}, binding site 2 (primary) is a low-affinity binding site with a binding constant of 6.3 x 10{sup -4}. These two binding sites act in an independent fashion, 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) have allowed us to propose a mechanism of metal activation for DtxR.

  1. [Removal of metal ions Cu2+, Cd+ and Pb+ from solutions by sorption on slag].

    Chen, Xiao; Hou, Wen-hua; Wang, Qun-hui


    Batch experiments were carried out to investigate the adsorption kinetics and thermodynamic characteristics of heavy metal ions Cu2+, Cd2+ and Pb2+ on the electric are furnace (EAF) slag from Baoshan Steel Factory. Several kinds of techniques including XRD analysis, BET specific surface analysis and SEM/EDS analysis were employed to determine the physico-chemical and surface characteristics of slag. Results indicated that the adsorption rate of heavy metal ions on the EAF slag was relatively high, and the sorption rate followed the order Cd2+ > Pb2+ > Cu2+. The adsorption kinetics obeyed first-order kinetics model (R2 > 0.99). Adsorption isotherm experiment showed that adsorption isotherm of heavy metal ions on slag fitted Langmuir model, and the maximum adsorption capacity of Cu2+, Cd2+ and Pb2+ was 0.101, 0.058 and 0.120 mmol x g(-1), respectively. The adsorption of heavy metal ions on slag was a spontaneous reaction (deltaG0 0). The effect of enthopy was the main driving force of the spontaneous adsorption reaction. The analysis results of SEM/EDS revealed the changes of surface morphology and chemical proportion before and after adsorption. Due to low-cost and high-efficiency, electric are furnace slag showed great potential for the treatment of heavy metal polluted wastewaters.

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

    Kaur, Sukhmanpreet


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

  3. Comparative Advantage

    Zhang, Jie; Jensen, Camilla


    that are typically explained from the supply-side variables, the comparative advantage of the exporting countries. A simple model is proposed and tested. The results render strong support for the relevance of supply-side factors such as natural endowments, technology, and infrastructure in explaining international...

  4. Building one-dimensional oxide nanostructure arrays on conductive metal substrates for lithium-ion battery anodes.

    Jiang, Jian; Li, Yuanyuan; Liu, Jinping; Huang, Xintang


    Lithium ion battery (LIB) is potentially one of the most attractive energy storage devices. To meet the demands of future high-power and high-energy density requirements in both thin-film microbatteries and conventional batteries, it is challenging to explore novel nanostructured anode materials instead of conventional graphite. Compared to traditional electrodes based on nanostructure powder paste, directly grown ordered nanostructure array electrodes not only simplify the electrode processing, but also offer remarkable advantages such as fast electron transport/collection and ion diffusion, sufficient electrochemical reaction of individual nanostructures, enhanced material-electrolyte contact area and facile accommodation of the strains caused by lithium intercalation and de-intercalation. This article provides a brief overview of the present status in the area of LIB anodes based on one-dimensional nanostructure arrays growing directly on conductive inert metal substrates, with particular attention to metal oxides synthesized by an anodized alumina membrane (AAM)-free solution-based or hydrothermal methods. Both the scientific developments and the techniques and challenges are critically analyzed.

  5. Elemental analyses of goundwater: demonstrated advantage of low-flow sampling and trace-metal clean techniques over standard techniques

    Creasey, C. L.; Flegal, A. R.

    The combined use of both (1) low-flow purging and sampling and (2) trace-metal clean techniques provides more representative measurements of trace-element concentrations in groundwater than results derived with standard techniques. The use of low-flow purging and sampling provides relatively undisturbed groundwater samples that are more representative of in situ conditions, and the use of trace-element clean techniques limits the inadvertent introduction of contaminants during sampling, storage, and analysis. When these techniques are applied, resultant trace-element concentrations are likely to be markedly lower than results based on standard sampling techniques. In a comparison of data derived from contaminated and control groundwater wells at a site in California, USA, trace-element concentrations from this study were 2-1000 times lower than those determined by the conventional techniques used in sampling of the same wells prior to (5months) and subsequent to (1month) the collections for this study. Specifically, the cadmium and chromium concentrations derived using standard sampling techniques exceed the California Maximum Contaminant Levels (MCL), whereas in this investigation concentrations of both of those elements are substantially below their MCLs. Consequently, the combined use of low-flow and trace-metal clean techniques may preclude erroneous reports of trace-element contamination in groundwater. Résumé L'utilisation simultanée de la purge et de l'échantillonnage à faible débit et des techniques sans traces de métaux permet d'obtenir des mesures de concentrations en éléments en traces dans les eaux souterraines plus représentatives que les résultats fournis par les techniques classiques. L'utilisation de la purge et de l'échantillonnage à faible débit donne des échantillons d'eau souterraine relativement peu perturbés qui sont plus représentatifs des conditions in situ, et le recours aux techniques sans éléments en traces limite l

  6. Synthesis of metallic glasses and metallic glass based composites in the Cu-Mo-Hf system by ion beam mixing

    BAI Xue; WANG TongLe; CUI YuanYuan; DING Ning; LI JiaHao; LIU BaiXin


    Single-phase and dual-phase metallic glasses as well as metallic glass based composites were synthesized in the Cu-Mo-Hf ternary metal system by 200 keV xenon ion beam mixing of far-from-equilibrium.It was found that Mo-Hf-based and Cu-Mo-based single-phase metallic glasses could be obtained at compositions around Cu17Mo20Hf63 and Cu34Mo57Hf9,respectively.Interestingly,at the nearly equal-atomic stoichiometry of Cu38Mo31Hf31,a dual-phase Cu-Mo-Hf metallic glass,consisting both of the Mo-Hf-based and Cu-Mo-based phases,was first obtained at relatively low irradiation doses ranging from (1-5)×1015 Xe+/cm2,and a single-phase metallic glass was eventually obtained at a dose of 7×1015 Xe+/cm2.In addition,two glass-based composites were obtained at the compositions of Cu14Mo62Hf24 and Cu77Mo14Hf9,and they consisted of the Mo-Hf based and Cu-Mo based metallic glasses,dissolved with some uniformly distributed BCC Mo-based and FCC Cu-based crystalline solid solutions,respectively.The formation mechanism of the above described non-equilibrium alloy phases was also discussed in terms of the atomic collision theory.

  7. Using Hydrogen Balloons to Display Metal Ion Spectra

    Maynard, James H.


    We have optimized a procedure for igniting hydrogen-filled balloons containing metal salts to obtain the brightest possible flash while minimizing the quantity of airborne combustion products. We report air quality measurements in a lecture hall immediately after the demonstration. While we recommend that this demonstration be done outdoors or in…

  8. Removal of Heavy Metal Ions from Wastewater by Using Biosorbents from Marine Algae-A Cost Effective New Technology


    Heavy metal pollution from industrial wastewater is a worldwide environmental issue. Biosorption of heavy metals by using biosorbents derived from various types of biomass has been shown to be effective for the uptake of heavy metal ions. In this study, biosorbents derived from the biomass of a group of marine macroalgae were used for the removal and recovery of heavy metal ions from aqueous solutions. Results indicated that the biosorbents have high uptake capacities and affinities for a number of heavy metal ions. The uptake capacities of the biosorbents were in the range of 1.0 to 1.5mmol·g-1 for divalent heavy metal ions. The kinetics of the uptake process was fast and the process can be used in both batch and fixed-bed operations. It appears that the biosorption process by using biosorbents from marine macroalgae can be an efficient and cost effective technology for the treatment of heavy metal containing wastewater.

  9. Hybrid metallic ion-exchanged waveguides for SPR biological sensing

    de Bonnault, S.; Bucci, D.; Zermatten, P.. J.; Charette, P. G.; Broquin, J. E.


    Glass substrates have been used for decades to create biosensors due to their biocompatibility, low thermal conductivity, and limited fluorescence. Among the different types of sensors, those based on surface plasmon resonance (SPR) allow exploitation of the sensing lightwave at the vicinity of the sensor surface where small entities such as DNA or proteins are located. In this paper, ion-exchanged waveguides and SPR are combined to create a multianalyte optical sensor integrated onto glass. First the principle of operation is introduced, then the theoretical analysis and design of the sensing element. Simulations have been carried out using the Aperiodic Fourier Modal Method (AFMM) and a custom software that handles ion-exchange index-profiles. Fabrication and characterization processes are also presented. Finally the first experimental spectra are displayed and discussed. The sensor presents a bulk sensibility of 5000nm/RIU.

  10. Hardening of Metallic Materials Using Plasma Immersion Ion Implantation (PIII)

    Xu, Yufan; Clark, Mike; Flanagan, Ken; Milhone, Jason; Nonn, Paul; Forest, Cary


    A new approach of Plasma Immersion Ion Implantation (PIII) has been developed with the Plasma Couette Experiment Upgrade (PCX-U). The new approach efficiently reduces the duty cycle under the same average power for PIII. The experiment uses a Nitrogen plasma at a relatively high density of 1010 1011 cm-3 with ion temperatures of working cycle. The samples (Alloy Steel 9310) are analyzed by a Vicker Hardness Tester to study the hardness and X-ray Photoelectron Spectroscopy (XPS) to study implantation density and depth. Different magnetic fields are also applied on samples to reduce the energy loss and secondary emission. Higher efficiency of implantation is expected from this experiment and the results will be presented. Hilldale Undergraduate/Faculty Research Fellowship of University of Wisconsin-Madison; Professor Cary Forest's Kellett Mid-Career Faculty Award.

  11. Development of a method employing chitosan to remove metallic ions from wastewater; Desenvolvimento de um metodo empregando quitosana para remocao de ions metalicos de aguas residuarias

    Janegitz, Bruno Campos; Lourencao, Bruna Claudia; Lupetti, Karina Omuro; Fatibello-Filho, Orlando [Universidade Federal de Sao Carlos (UFSCAR), SP (Brazil). Dept. de Quimica


    In this work a method was developed for removing metallic ions from wastewaters by co-precipitation of Cu{sup 2+}, Pb{sup 2+}, Cd{sup 2+}, Cr{sup 3+} and Hg{sup 2+} with chitosan and sodium hydroxide solution. Solutions of these metallic ions in the range from 0.55 to 2160 mg L{sup -1} were added to chitosan dissolved in 0.05 mol L{sup -1} HCl. For the co-precipitation of metal-chitosan-hydroxide a 0.17 mol L{sup -1} NaOH solution was added until pH 8.5-9.5. A parallel study was carried out applying a 0.17 mol L{sup -1} NaOH solution to precipitate those metallic ions. Also, a chitosan solid phase column was used for removing those metallic ions from wastewaters. (author)

  12. Transport of yttrium metal ions through fibers supported liquid membrane solvent extraction

    A.G.Gaikwad; A.M.Rajput


    A novel idea of transport of yttrium(Ⅲ) metal ions through fibers supported liquid membrane in two stage processes namely source to membrane and membrane to receiving phase has been proposed.The fibers supported liquid membrane was impregnated with different concentrations carrier.The experimental variables explored were concentration of yttrium(Ⅲ) ions,pH of source phase,PC-88A concentration in membrane phase,acid concentration in receiving phase and stirring speed.The pre-concentration of yttrium(Ⅲ) ions ...

  13. Synthesis and Characterization of Layered Double Hydroxides Containing Optically Active Transition Metal Ion

    Tyagi, S. B.; Kharkwal, Aneeta; Nitu; Kharkwal, Mamta; Sharma, Raghunandan


    The acetate intercalated layered double hydroxides of Zn and Mn, have been synthesized by chimie douce method. The materials were characterized by XRD, TGA, CHN, IR, XPS, SEM-EDX and UV-visible spectroscopy. The photoluminescence properties was also studied. The optical properties of layered hydroxides are active transition metal ion dependent, particularly d1-10 system plays an important role. Simultaneously the role of host - guest orientation has been considered the basis of photoluminescence. Acetate ion can be exchanged with iodide and sulphate ions. The decomposed product resulted the pure phase Mn doped zinc oxide are also reported.

  14. Extraction of alginate biopolymer present in marine alga sargassum filipendula and bioadsorption of metallic ions

    Sirlei Jaiana Kleinübing; Frederico Gai; Caroline Bertagnolli; Meuris Gurgel Carlos da Silva


    This paper studies the bioadsorption of Pb2+, Cu2+, Cd2+ and Zn2+ ions by marine alga Sargassum filipendula and by the alginate biopolymer extracted from this alga. The objective is to evaluate the importance of this biopolymer in removing different metallic ions by the marine alga S. filipendula. In the equilibrium study, the same affinity order was observed for both bioadsorbents: Pb2+ > Cu2+ > Zn2+ > Cd2+. For Pb2+ and Cu2+ ions when the alginate is isolated and acting as bioadsorbents, ad...

  15. Effect of metal-ion doping on the optical properties of nanocrystalline ZnO thin films

    Mendoza-Galván, A.; Trejo-Cruz, C.; Lee, J.; Bhattacharyya, D.; Metson, J.; Evans, P. J.; Pal, U.


    Optical properties of metal (Al, Ag, Sb, and Sn)-ion-implanted ZnO films have been studied by ultraviolet-visible spectroscopy and spectroscopic ellipsometric techniques. The effects of metal-ion doping on the optical band gap (Eg), refractive index (n), and extinction coefficient (k) of nanocrystalline ZnO films have been studied for the similar implantation dose of all the metal ions. The ellipsometric spectra of the ion-implanted samples could be well described by considering an air/roughness/ZnO-M (layer 1)/ZnO (layer 2)/glass model. The band gap of ZnO films increases with Al ion doping and decreases with doping of Ag, Sb, and Sn ions. The refractive index of ZnO films in the visible spectral region increases substantially on Sb and Sn ion doping, while it decreases to some extent with Al ion doping.

  16. Sugar-metal ion interactions: The coordination behavior of cesium ion with lactose, D-arabinose and L-arabinose

    Jiang, Ye; Xue, Junhui; Wen, Xiaodong; Zhai, Yanjun; Yang, Limin; Xu, Yizhuang; Zhao, Guozhong; Kou, Kuan; Liu, Kexin; Chen, Jia'er; Wu, Jinguang


    The novel cesium chloride-lactose complex (CsCl·C12H22O10 (Cs-Lac), cesium chloride-D-arabinose and L-arabinose complexes (CsCl·C5H10O5, Cs-D-Ara and Cs-L-Ara) have been synthesized and characterized using X-ray diffraction, FTIR, FIR, THz and Raman spectroscopies. Cs+ is 9-coordinated to two chloride ions and seven hydroxyl groups from five lactose molecules in Cs-Lac. In the structures of CsCl-D-arabinose and CsCl-L-arabinose complexes, two kinds of Cs+ ions coexist in the structures. Cs1 is 10-coordinated with two chloride ions and eight hydroxyl groups from five arabinose molecule; Cs2 is 9-coordinated to three chloride ions and six hydroxyl groups from five arabinose molecules. Two coordination modes of arabinose coexist in the structures. α-D-arabinopyranose and α-L-arabinopyranose appear in the structures of Cs-D-Ara and Cs-L-Ara complexes. FTIR and Raman results indicate variations of hydrogen bonds and the conformation of the ligands after complexation. FIR and THz spectra also confirm the formation of Cs-complexes. Crystal structure, FTIR, FIR, THz and Raman spectra provide detailed information on the structure and coordination of hydroxyl groups to metal ions in the cesium chloride-lactose, cesium chloride-D- and L-arabinose complexes.

  17. Characterization of surface enhancement of carbon ion-implanted TiN coatings by metal vapor vacuum arc ion implantation

    Chang, C L


    The modification of the surfaces of energetic carbon-implanted TiN films using metal vapor vacuum arc (MEVVA) ion implantation was investigated, by varying ion energy and dose. The microhardness, microstructure and chemical states of carbon, implanted on the surface layer of TiN films, were examined, as functions of ion energy and dose, by nanoindenter, transmission electron microscopy, Auger electron spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction. Results revealed that the microhardness increased from 16.8 up to 25.3 GPa and the friction coefficient decreased to approximately 0.2, depending on the implanted ion energy and dose. The result is attributed to the new microcrystalline phases of TiCN and TiC formed, and carbon concentration saturation of the implanted matrix can enhance the partial mechanical property of TiN films after MEVVA treatment. The concentration distribution, implantation depth and chemical states of carbon-implanted TiN coatings depended strongly on the ion dose and...


    Supported 2-hydroxy-5-nonyl-acetophenone oxime (LIX-84) liquid membranes have potential applications for the removal (or recovery) of copper ions from waste streams. But, the stability of such a liquid membrane remains the major hurdle for its practical applications. Inorganic su...

  19. Aqueous batteries based on mixed monovalence metal ions: a new battery family.

    Chen, Liang; Zhang, Leyuan; Zhou, Xufeng; Liu, Zhaoping


    As existing battery technologies struggle to meet the requirements for widespread use in the field of large-scale energy storage, new concepts are urgently needed to build batteries with high energy density, low cost, and good safety. Here, we demonstrate two new aqueous batteries based on two monovalence metal ions (Li(+) /K(+) and Na(+) /K(+) ) as charge-transfer ions, Ni1 Zn1 HCF/TiP2 O7 and Ni1 Zn1 HCF/NaTi2 (PO4 )3 . These new batteries are unlike the conventional "rocking-chair" aqueous metal-ion batteries based on the migration of one type of shuttle ion between cathode and anode. They can deliver specific energy of 46 Wh kg(-1) and 53 Wh kg(-1) based on the total mass of active materials; this is superior to current aqueous battery systems based on sodium-ion and/or potassium-ion technologies. These two new batteries together with the previously developed Li(+) /Na(+) mixed-ion battery not only constitute a new battery family for energy storage, but also greatly broaden our horizons for battery research.

  20. Obtaining sorbents of metal ions based on yeast cells Rhodotorula glutinis

    Zh. Tattibayeva


    Full Text Available Ability to separate Cu2+ and Pb2+ ions from solution using yeast cells Rhodotorulа glutinis were considered. The degree of water purification in this case is of 60-70%. To increase the degree of binding of metal ions with cells and facilitate separation processes of water sorbents their immobilization on the surface of the water in the presence of polyethyleneimine was carried out. It is shown that under optimal conditions on the surface of 1 g diatomite 18 ∙ 106 cells is adsorbed. The high sorption capacity of diatomite justified its porosity. IR spectroscopic study of the interaction of the ions Cu2+ and Pb2+ with cell surface showed that high affinity Pb2 + ions to the surface of yeast cells is connected with form of slightly soluble compounds with the phosphate ions.

  1. Synthetic, structural, and theoretical investigations of alkali metal germanium hydrides--contact molecules and separated ions.

    Teng, Weijie; Allis, Damian G; Ruhlandt-Senge, Karin


    The preparation of a series of crown ether ligated alkali metal (M=K, Rb, Cs) germyl derivatives M(crown ether)nGeH3 through the hydrolysis of the respective tris(trimethylsilyl)germanides is reported. Depending on the alkali metal and the crown ether diameter, the hydrides display either contact molecules or separated ions in the solid state, providing a unique structural insight into the geometry of the obscure GeH3- ion. Germyl derivatives displaying M--Ge bonds in the solid state are of the general formula [M([18]crown-6)(thf)GeH3] with M=K (1) and M=Rb (4). The compounds display an unexpected geometry with two of the GeH3 hydrogen atoms closely approaching the metal center, resulting in a partially inverted structure. Interestingly, the lone pair at germanium is not pointed towards the alkali metal, rather two of the three hydrides are approaching the alkali metal center to display M--H interactions. Separated ions display alkali metal cations bound to two crown ethers in a sandwich-type arrangement and non-coordinated GeH3- ions to afford complexes of the type [M(crown ether)2][GeH3] with M=K, crown ether=[15]crown-5 (2); M=K, crown ether=[12]crown-4 (3); and M=Cs, crown ether=[18]crown-6 (5). The highly reactive germyl derivatives were characterized by using X-ray crystallography, 1H and 13C NMR, and IR spectroscopy. Density functional theory (DFT) and second-order Møller-Plesset perturbation theory (MP2) calculations were performed to analyze the geometry of the GeH3- ion in the contact molecules 1 and 4.

  2. Trade Advantages

    Mei Xinyu


    As the world's largest trading nation,its largest exporter and second largest importer,China wields extensive influence on global trade and the world economy,China's advantages of course lie not only in the stable foreign trade policy decided by the recently held Central Economic Work Conference,but also in the strength and resilience of a broadbased and fast-growing economy.

  3. [The imbalance of metal-containing proteins and free metal ions in the amniotic fluid during fetal growth].

    Pogorelova, T N; Linde, V A; Gunko, V O; Selyutina, S N


    The levels of zinc, copper, iron, and magnesium ions, and some of their binding proteins have been investigated in an amniotic fluid under the fetal growth retardation (FGR). FGR, developed under conditions of placental insufficiency, is characterized by a decrease in the content of zinc, iron, and magnesium ions and by an increase in the copper content in the amniotic fluid in the II and III trimesters of pregnancy. During these trimesters the levels of ceruloplasmin, ferritin, and Ca2+,Mg2+-ATPase were lower in FGR, while the level of zinc-a-2-glycoprotein was higher than during the same periods of normal pregnancy. Changes in the parameters studied in the amniotic fluid were associated with developmental disorders of the newborns. These changes obviously have a pathogenetic importance in the development of FGR, and the levels of metal ions and their ratio in the amniotic fluid can be used as markers of the pre- and postnatal pathology.

  4. Binary ion exchange of metal ions in Y and X zeolites

    M.A.S.D. Barros


    Full Text Available The ion exchange of Na for Cr/K, Cr/Mg and Cr/Ca in Y and X zeolites was studied using breakthrough curves. It was observed that Cr3+ ions were able to remove some competitive ions that had already been exchanged at the zeolitic sites, producing a sequential ion exchange. Some mass transfer parameters such as length of unused bed, overall mass transfer coefficient, operational ratio and dimensionless variance were studied. Chromium uptake was influenced much more by the competing ion in the NaX zeolite columns. The dimensionless variance indicated that Cr/K solution produced a greater axial dispersion than the Cr/Mg and Cr/Ca systems, probably due to some interaction between Cr3+ and K+ ions. The order of dynamic selectivity, provided by the cation uptake, was Cr3+ > Ca2+, Cr3+ > Mg2+ and Cr3+ > K+ for NaY zeolite and Ca2+ ~Cr3+, Mg2+ > Cr3+ and Cr3+ > K+ for NaX zeolite. Due to the more favorable mass transfer parameters and higher affinity for Cr3+, it was concluded that NaY zeolite was more efficient at chromium uptake in competitive systems.

  5. Study on the Adsorption of Metal Ions by Immobilized Marine Algae with the Existence of Clay


    The process of adsorption of metal ions by immobilized marine algae with the existence of clay was investigated. It can be noted from the results that, after mixing with clay,the adsorption rate increases rapidly with the increasing amount of the marine algae. When pH=5, the best ratio between the clay and the marine algae is 1:4 for Pb2+. The result of in situ handling of the waste water containing heavy metals shows that the average adsorption rates of heavy metal irons Cu2+, Cd2+, Pb2+ and Ni2+ are all over 70 %.

  6. Depletive stripping chronopotentiometry : a major step forward in electrochemical stripping techniques for metal ion speciation analysis

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


    A comparative evaluation of the utility of the various modes of stripping chronopotentiometry (SCP) for trace metal speciation analysis is presented in the broad context of stripping voltammetric techniques. The remarkable fundamental advantages of depletive SCP at scanned deposition potential (SSCP

  7. Study of structural and spectroscopic behavior of Sm3+ ions in lead-zinc borate glasses containing alkali metal ions

    Sasi Kumar, M. V.; Babu, S.; Rajeswara Reddy, B.; Ratnakaram, Y. C.


    High luminescence behavior of rare earth inorganic glasses have a variety of uses in the industry. In the past few decades, rare earth ions with characteristic photonics applications are being hosted by heavy metal oxide glasses. Among the rare earth ions Sm3+ ion has features which make it apt for high density optical storage. The authors of the paper have experimented to synthesize Sm3+ doped glasses. In this regard a new series of borate glasses doped with 1 mol% Sm3+ ion are developed by using melt-quenching technique. XRD, FTIR, optical absorption, luminescence techniques are used to study the various characteristics of Sm3+ ion in the present glass matrices. The XRD spectra confirms the amorphous nature of glasses. Further, the researchers have used differential thermal analysis to study the glass transition temperature. The structural groups in the prepared glasses are studied using Fourier transform infrared spectra. From the measurement of its optical absorption, three phenomenological Judd-Ofelt intensity parameters (Ω2, Ω4 and Ω6) have been computed. Based on these Judd-Ofelt intensity parameters, radiative properties such as radiative probabilities (Arad), branching ratios (β), and radiative life time (τR) are calculated. The excitation spectra of Sm3+ doped lithium heavy metal borate glass matrix is recorded under the emission wavelength of 600 nm. The emission spectra are recorded under 404 nm excitation wavelength. From various emission transitions, 4G5/2 → 6H7/2 and 4G5/2 → 6H9/2 bands could be of interest for various applications. The decay profiles of 4G5/2 level exhibit single exponential nature in all the prepared glass matrices. The potassium glass matrix exhibits higher quantum efficiency than the other glass matrices. Finally, by going through these several spectroscopic characterizations, it is concluded that the prepared Sm3+ doped lead-zinc borate glasses might be useful for visible light applications.

  8. Study of structural and spectroscopic behavior of Sm3+ ions in lead-zinc borate glasses containing alkali metal ions

    Sasi Kumar, M. V.; Babu, S.; Rajeswara Reddy, B.; Ratnakaram, Y. C.


    High luminescence behavior of rare earth inorganic glasses have a variety of uses in the industry. In the past few decades, rare earth ions with characteristic photonics applications are being hosted by heavy metal oxide glasses. Among the rare earth ions Sm3+ ion has features which make it apt for high density optical storage. The authors of the paper have experimented to synthesize Sm3+ doped glasses. In this regard a new series of borate glasses doped with 1 mol% Sm3+ ion are developed by using melt-quenching technique. XRD, FTIR, optical absorption, luminescence techniques are used to study the various characteristics of Sm3+ ion in the present glass matrices. The XRD spectra confirms the amorphous nature of glasses. Further, the researchers have used differential thermal analysis to study the glass transition temperature. The structural groups in the prepared glasses are studied using Fourier transform infrared spectra. From the measurement of its optical absorption, three phenomenological Judd-Ofelt intensity parameters (Ω2, Ω4 and Ω6) have been computed. Based on these Judd-Ofelt intensity parameters, radiative properties such as radiative probabilities (Arad), branching ratios (β), and radiative life time (τR) are calculated. The excitation spectra of Sm3+ doped lithium heavy metal borate glass matrix is recorded under the emission wavelength of 600 nm. The emission spectra are recorded under 404 nm excitation wavelength. From various emission transitions, 4G5/2 → 6H7/2 and 4G5/2 → 6H9/2 bands could be of interest for various applications. The decay profiles of 4G5/2 level exhibit single exponential nature in all the prepared glass matrices. The potassium glass matrix exhibits higher quantum efficiency than the other glass matrices. Finally, by going through these several spectroscopic characterizations, it is concluded that the prepared Sm3+ doped lead-zinc borate glasses might be useful for visible light applications.


    SHEN Zhiquan; ZHANG Fuyao; ZHANG Yifeng


    Pervaporation separation of water-acetic acid mixtures through Poly (AN-co-AA)membranes and rare earth metal ions treated Poly(AN-co-AA)membranes was investigated for the first time. The results showed that the treatment with rare earth metal ions could greatly improve the characteristics of the separation of water-acetic acid mixtures.

  10. Metal-ion catalyzed polymerization in the eutectic phase in water-ice

    Monnard, Pierre-Alain; Szostak, Jack W.


    The emergence of an RNA world requires among other processes the non-enzymatic, template-directed replication of genetic polymers such as RNA or related nucleic acids, possibly catalyzed by metal ions. The absence of uridilate derivative polymerization on adenine containing templates has been the...

  11. Polarographic Determination of Composition and Thermodynamic Stability Constant of a Complex Metal Ion.

    Marin, Dolores; Mendicuti, Francisco


    Describes a laboratory experiment designed to encourage laboratory cooperation among individual undergraduate students or groups. Notes each student contributes results individually and the exchange of data is essential to obtain final results. Uses the polarographic method for determining complex metal ions. (MVL)

  12. Research on the Release of Theanine in the Exist of Metal Ions in Natural Water

    Zhi-xu Zhang


    Full Text Available Theanine is a main component in tea leaf, it is the key factor to influence the nutrition value and flavor when the tea leaf is brewing. Natural water is the most-used extractant to dissolve out the theanine. It is recorded in ancient books that dissolution rate is quite different in different kinds of natural water. Recent study shows its correlation with the complexing abilities of metal ions. The thesis is trying to explain the law between the release of theanine and metal ions through designed model test. Response surface experiments showed that in the mixed solution of 1.74 mg/L Ca2+, 21.63 mg/L Na+, 5.55 mg/L Mg2+ and 4.86 mg/L Al3+., the release of theanine reaches the peak value 0.88 mg/mL. It is also found that in the exist of Ca2+, free theanine is increasing with total metal ions while free theanine is decreasing with the increasement of total metal ions in the absence of Ca2+.

  13. Studies on Synthesis of a Cycloheptapeptide and Effects of Different Metal Ions on the Cyclization

    LIU,Mian(刘勉); YE,Yun-Hua(叶蕴华)


    A cyclic heptapeptide, c(Gly-Ile-Pro-Tyr-Ile-Ala-Ala), which was isolated and identified from Stellaria yunnanensis Franch (M), was synthesized by solution method for the first tine.Protected heptapeptide Z-Gly-Ile-Pro-Tyr-Ile-Ala-Ala-OBzl was synthesized with 3-(diethoxy-phosphoryloxy)-1,2,3-benzotriazin-4(3H)-one (DEPBT) as a coupling reagent. After deprotection of benzyl and benzyloxycarbonyl groups, a free linear heptapeptide H-Gly-Ile-Pro-Tyr-Ile-Ala-Ala-OH was cyclized in DMF (2× 10-3 mol/L) in the presence of nine different metal ions, i.e., Li+, Na+, K+, Cs+, Mg2+, Ca2+,Ba2+, Ni2++ and Cr3+ respectively, using DEPBT as a coupling reagent. Univalent metal ion Cs + enhanced both the cyclization yield and cyclization rate of H-Gly-Ile- Pro-Tyr-Ile-Ala-AlaOH, while some bivalent metal ions, such as Mg2+, Ca2+ and Ni2+ decreased the yields of c (Gly-Ile-Pro-Tyr-Ile-Ala-Ala)drastically. Trivalent metal ion Cr3 + even inhibited the cyclization reaction completely.

  14. A New Fluorescent Sensor for Transition Metal Ions in Aqueous Solution


    A new fluorescent sensor consisted of fluorenyl and dioxotetraaza unit, namely, 2,10-dimethyl-6-(9-fluorenyl)-1,4,8,11-tetraazaundencane-5,7-dione (L), was synthesized. It is a fluorescent sensor for transition metal ions in aqueous solution.

  15. Multiheteromacrocycles that Complex Metal Ions. Fourth Progress Report, 1 May 1977 -- 30 April 1978

    Cram, D. J.


    Results are reported in a program to design, synthesize, and evaluate polycyclic host organic compounds for their abilities to complex and lipophilize guest metal ions. Work during the reporting period was devoted to synthesis and study of cyclohexametaphenylenes and cyclic phosphine oxides. (JRD)

  16. Metal-ion dependent catalytic properties of Sulfolobus solfataricus class II α-mannosidase

    Nielsen, Jonas Willum; Poulsen, Nina Rødtness; Johnsson, Anna Margit Susanne;


    The active site for the family GH38 class II α-mannosidase is constituted in part by a divalent metal ion, mostly Zn(2+), as revealed in the crystal structures of enzymes from both animal and bacterial sources. The metal ion coordinates to the bound substrate and side chains of conserved amino acid...... residues. Recently, evidence has accumulated that class II α-mannosidase is active in complex with a range of divalent metal ions. In the present work, with employment of the class II α-mannosidase, ManA, from the hyperthermophilic archaeon Sulfolobus solfataricus, we explored the influence of the divalent...... metal ion on the associated steady-state kinetic parameters, K(M) and k(cat), for various substrates. With p-nitrophenyl-α-d-mannoside as a substrate, the enzyme showed activity in the presence of Co(2+), Cd(2+), Mn(2+), and Zn(2+), whereas Ni(2+) and Cu(2+) were inhibitory and nonactivating. Co(2...

  17. Metal Ion Complexes with HisGly: Comparison with PhePhe and PheGly

    Dunbar, R.C.; Oomens, J.; Berden, G.; Lau, J.K.C.; Verkerk, U.H.; Hopkinson, A.C.; Siu, K.W.M.


    Gas-phase complexes of five metal ions with the dipeptide HisGly have been characterized by DFT computations and by infrared multiple photon dissociation spectroscopy (IRMPD) using the free electron laser FELIX. Fine agreement is found in all five cases between the predicted IR spectral features of

  18. Specificity of the metalloregulator CueR for monovalent metal ions

    Szunyogh, Dániel; Szokolai, Hajnalka; Thulstrup, Peter Waaben;


    (II) , and Hg(II) binding to model systems encompassing the metal-ion-binding loop of CueR from E. coli and V. cholerae. In the presence of Ag(I) , a conserved cysteine residue displays a pKa value for deprotonation of the thiol that is close to the physiological pH value. This property is only observed...

  19. Energy band gap and optical transition of metal ion modified double crossover DNA lattices.

    Dugasani, Sreekantha Reddy; Ha, Taewoo; Gnapareddy, Bramaramba; Choi, Kyujin; Lee, Junwye; Kim, Byeonghoon; Kim, Jae Hoon; Park, Sung Ha


    We report on the energy band gap and optical transition of a series of divalent metal ion (Cu(2+), Ni(2+), Zn(2+), and Co(2+)) modified DNA (M-DNA) double crossover (DX) lattices fabricated on fused silica by the substrate-assisted growth (SAG) method. We demonstrate how the degree of coverage of the DX lattices is influenced by the DX monomer concentration and also analyze the band gaps of the M-DNA lattices. The energy band gap of the M-DNA, between the lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO), ranges from 4.67 to 4.98 eV as judged by optical transitions. Relative to the band gap of a pristine DNA molecule (4.69 eV), the band gap of the M-DNA lattices increases with metal ion doping up to a critical concentration and then decreases with further doping. Interestingly, except for the case of Ni(2+), the onset of the second absorption band shifts to a lower energy until a critical concentration and then shifts to a higher energy with further increasing the metal ion concentration, which is consistent with the evolution of electrical transport characteristics. Our results show that controllable metal ion doping is an effective method to tune the band gap energy of DNA-based nanostructures.

  20. Preparation and adsorption behavior for metal ions and humic acid of chitosan derivatives crosslinked by irradiation


    This article deals with the determination of the adsorption properties of metal ions and humic acid in water on crosslinked chitosan derivatives (carboxymethylchitosan) which were formed using the irradiation technique without any additives. The solubility test of these crosslinked materials were investigated in acidic, alkaline media,distilled water, and certain organic solvents. Scanning electron microscopic (SEM) images showed that the crosslinked chitosan derivatives possessed a porous morphological structure. Charged characteristic analyses demonstrated typically pH-dependent properties of the crosslinked materials. The adsorption studies were carried out by the batch method at room temperature. Adsorption of heavy metal ions (such as Cu2+, Cd2+) and humic acid onto crosslinked samples was found to be strongly pH-dependent. Adsorption kinetic studies indicated the rapid removal of metal ions, and humic acid from the aqueous solutions. Moreover, isothermal adsorption data revealed that Cu2+, Cd2+,and humic acid were removed by these crosslinked materials with high efficiency. Adsorption isothermal data were interpreted well by the Langmuir equation. These crosslinked carboxymethylated chitosan derivatives indicate favorable adsorption of metal ions and humic acid.

  1. A novel biodegradable β-cyclodextrin-based hydrogel for the removal of heavy metal ions.

    Huang, Zhanhua; Wu, Qinglin; Liu, Shouxin; Liu, Tian; Zhang, Bin


    A novel biodegradable β-cyclodextrin-based gel (CAM) was prepared and applied to the removal of Cd(2+), Pb(2+) and Cu(2+) ions from aqueous solutions. CAM hydrogel has a typical three-dimensional network structure, and showed excellent capability for the removal of heavy metal ions. The effect of different experimental parameters, such as initial pH, adsorbent dosage and initial metal ion concentration, were investigated. The adsorption isotherm data fitted well to the Freundlich model. The adsorption capacity was in the order Pb(2+)>Cu(2+)>Cd(2+) under the same experimental conditions. The maximum adsorption capacities for the metal ions in terms of mg/g of dry gel were 210.6 for Pb(2+), 116.41 for Cu(2+), and 98.88 for Cd(2+). The biodegradation efficiency of the resin reached 79.4% for Gloeophyllum trabeum. The high adsorption capacity and kinetics results indicate that CAM can be used as an alternative adsorbent to remove heavy metals from aqueous solution. Published by Elsevier Ltd.

  2. Coloring a Superabsorbent Polymer with Metal Ions: An Undergraduate Chemistry Experiment

    Yaung, Jing-Fun; Chen, Yueh-Huey


    A novel undergraduate chemistry experiment involving superabsorbent polymers commonly used in diapers and other personal care products is described. Students observe the removal of divalent transition-metal ions from aqueous solutions by the polymers. With the procedures provided, students are able to color the superabsorbent polymers with metal…

  3. Surface Modification of Polypropylene Membrane Using Biopolymers with Potential Applications for Metal Ion Removal

    Omar Alberto Hernández-Aguirre


    Full Text Available This work aims to present the modification of polypropylene (PP membranes using three different biopolymers, chitosan (CHI, potato starch (PS, and cellulose (CEL, in order to obtain three new materials. The modified membranes may be degraded easier than polypropylene ones and could be used as selective membranes for metal ions removal, among other applications. For this purpose, the UV energy induced graft copolymerization reaction among polypropylene membrane, acrylic acid, benzophenone (as photoinitiator, and the biopolymer (CHI, PS, or CEL was conducted. The results of FT-IR-ATR, XRD, TGA, DSC, SEM, BET, and AFM analyses and mechanical properties clearly indicate the successful modification of the membrane surface. The change of surface wettability was monitored by contact angle. The grafting reaction depends on natural polymer, reaction time, and concentration. In order to prove the potential application of the modified membranes, a preliminary study of sorption of metal ion was carried out. For this purpose, the PP-CHI membrane was chosen because of the high hydrophilicity, proportionate to -OH and NH2; these groups could act as ligands of metal ions, provoking the interaction between PP-CHI and M+ (PP-CHI-M+ and therefore the metal ion removal from water.

  4. Using amino acids for the chromatofocusing of metal ions on silica with bonded tetraethylenepentamine groups

    Ivanov, A. V.


    Amino acid-based eluents are used for the chromatofocusing of metal ions on Tetren-SiO2 chelating sorbent (silica with bonded tetraethylenepentamine groups) for the first time. The smoothest quasilinear pH gradients form for eluents based on glutamic and aspartic acids. The separation of Mn2+, Cr3+, Co2+, Ni2+, and Cu2+ is achieved.

  5. Absorption and luminescence properties of terbium ions in heavy metal glasses

    Żur, Lidia, E-mail:; Sołtys, Marta; Pisarska, Joanna; Pisarski, Wojciech A.


    Highlights: •Tb-doped heavy metal glasses were studied as a function of glass composition. •Excitation and luminescence spectra of Tb ions in heavy metal glasses were examined. •Luminescence intensity ratios (G/B) and measured lifetimes of Tb were determined. •Correlation between G/B factor, measured lifetimes and energy phonon was proposed. -- Abstract: Heavy metal glasses doped with Tb{sup 3+} ions have been investigated. Influence of glass-former oxides on the absorption and luminescence properties of terbium ions in inorganic glasses containing lead are discussed. Green emission line located at 543 nm due to {sup 5}D{sub 4} → {sup 7}F{sub 5} transition of Tb{sup 3+} was observed as a most intensive line. Green-to-blue luminescence ratio related to the integrated emission intensity of the {sup 5}D{sub 4} → {sup 7}F{sub 5} transition to that of the {sup 5}D{sub 4} → {sup 7}F{sub 6} transition was calculated and examined as a function of glass composition. Luminescence lifetimes for the {sup 5}D{sub 4} excited state of Tb{sup 3+} ions in heavy metal glasses were also determined. Correlation between green-to-blue luminescence ratios, measured lifetimes and the energy phonon of the glass hosts was proposed.

  6. Study on preparation of Luffa activated carbon and its adsorption of metal ions

    Zhai, Kuilu; Li, Zichao; Li, Qun


    In this paper, loofah was used as raw material and alkali and hydrogen peroxide were used to pre-oxidize. The activated carbon was activated by zinc chloride, and the activated carbon was used to desorb the heavy metal ions nickel and copper. The removal efficiency of heavy metal ions was studied under different conditions. The effects of retinervus Luffae Fructus active carbon adsorption of metal ions on process conditions, including metal ion concentration, reaction temperature, loofah activated carbon types and activated carbon dosage. In the present study, in different strain rate on the loofah sponge material compression tests in a wide range of density from 24 to 64 kg cubic meters. Luffa fibers and followed by carbonization to prepare MCAC KOH activation. MCAC has dense in parallel channels 10 mm in diameter and 4 - 0.3 - 1 mm wall thickness, which is inherited from the native structure of Luffa. Micro and middle holes are formed on the inner surface of the channel wall to form a hierarchical porous structure.

  7. Lithium-Ion-Battery Anode Materials with Improved Capacity from a Metal-Organic Framework.

    Lin, Xiao-Ming; Niu, Ji-Liang; Lin, Jia; Wei, Lei-Ming; Hu, Lei; Zhang, Gang; Cai, Yue-Peng


    We present a porous metal-organic framework (MOF) with remarkable thermal stability that exhibits a discharge capacity of 300 mAh g(-1) as an anode material for a lithium-ion battery. Pyrolysis of the obtained MOF gives an anode material with improved capacity (741 mAh g(-1)) and superior cyclic stability.

  8. Metal Ions Extraction with Glucose Derivatives as Chelating Reagents in Supercritical Carbon Dioxide

    Guo Chen YANG; Hai Jian YANG


    A series of glucose derivatives have been used as chelating reagents to extract metal ions in supercritical carbon dioxide. With perfluoro-1-octanesulfonic acid tetraethylammonium salt as additive, glucose derivatives were selective for Sr2+ and Pb2+ extraction in supercritical carbon dioxide.

  9. Continuous-wave broadband emitter based on a transition-metal-ion-doped waveguide

    Pollnau, M.; Salathé, R.P.; Bhutta, T.; Shepherd, D.P.; Eason, R.W.


    We demonstrate the suitability of a simple continuous-wave-pumped transition-metal-ion-doped waveguide as a broadband light source in the wavelength region 600–1000 nm for interferometric applications. Spatially coherent (single mode in the confined direction), spectrally broadband (~130-nm FWHM) lu

  10. Interactions between humic acid and hematite and their effects on metal ion speciation

    Vermeer, A.W.P.


    The impact of toxic chemicals (like metal ions) on the environment is a phenomenon that has been recognised as a mayor problem over the last decades. The speciation of these chemicals determines whether or not a contaminated site has to be regarded as dangerous. The fate of the

  11. Biosorption of Heavy Metal Ions from Aqueous Solutions Using a Biomaterial

    Innocent OBOH


    Full Text Available An increase in population initiating rapid industrialization was found to consequently increase the effluents and domestic wastewater into the aquatic ecosystem. Heavy metals are major toxicants found in industrial wastewaters; they may adversely affect the biological treatment of wastewater. Conventional methods for the removal of heavy metals from waste waters are often cost prohibitive hence, there is a need for cheap methods for effluent treatment. The residual metallic ion concentrations were determined using an Atomic Absorption Spectrophotometer (AAS. The results obtained after contacting for 120 minutes showed that Neem leaves achieved the percent removal of 76.8, 67.5, 58.4 and 41.45 for Cu2+, Ni2+, Zn2+ and Pb2+ ions respectively. The percent removal of Ni2+ ions was 68.75 with an effective dose of 1.0 g of Neem leaves (bioadsorbent. The ability of Neem leaves to absorb metal ions as shown from the results can be used for the development of an efficient, clean and cheap technology for effluent treatment.

  12. How Do Metal Ion Levels Change over Time in Hip Resurfacing Patients? A Cohort Study

    Lucia Savarino


    Full Text Available Metal-on-metal hip resurfacing (MOM-HR is offered as an alternative to traditional hip arthroplasty for young, active adults with advanced osteoarthritis. Nevertheless, concerns remain regarding wear and corrosion of the bearing surfaces and the resulting increase in metal ion levels. We evaluated three cohorts of patients with Birmingham hip resurfacing (BHR at an average follow-up of 2, 5, and 9 years. We asked whether there would be differences in ion levels between the cohorts and inside the gender. Nineteen patients were prospectively analyzed. The correlation with clinical-radiographic data was also performed. Chromium, cobalt, nickel, and molybdenum concentrations were measured by atomic absorption spectrophotometry. Chromium and cobalt levels demonstrated a tendency to decrease over time. Such tendency was present only in females. An inverse correlation between chromium, implant size, and Harris hip score was present at short term; it disappeared over time together with the decreased ion levels. The prospective analysis showed that, although metal ion levels remained fairly constant within each patient, there was a relatively large variation between subjects, so mean data in this scenario must be interpreted with caution. The chronic high exposure should be carefully considered during implant selection, particularly in young subjects, and a stricter monitoring is mandatory.

  13. Effects of metal ions and cosolutes on G-quadruplex topology.

    Fujii, Taiga; Podbevšek, Peter; Plavec, Janez; Sugimoto, Naoki


    Topologies of G-quadruplexes depend on oligonucleotide sequences and on environmental factors, and the diversity of G-quadruplex topologies complicates investigation of functions of these nucleic acid structures. To investigate how metal ions and cosolutes regulate topologies of G-quadruplexes, we stabilized the antiparallel conformation by insertion of 2'-deoxyxanthosine and 8-oxo-2'-deoxyguanosine into selected positions of an oligonucleotide. Thermodynamic analyses of the oligonucleotide revealed that Na(+) stabilized the antiparallel G-quadruplex, whereas K(+) destabilized this topology. This result suggests that metal ions selectively stabilize G-quadruplex topologies with cavities between G-quartet planes of certain sizes. In the presence of KCl in 20wt% poly(ethylene glycol) with average molecular weight of 200, the antiparallel basket-type G-quadruplex conformation was not stabilized compared with the dilute condition. In the presence of NaCl, the cosolute did stabilize the G-quadruplex with respect to the dilute condition. The presented data show that metal ions and cosolutes regulate topologies of G-quadruplexes through mechanisms that depend on sizes of metal ion cavities and hydration states.

  14. Oxidative damage to collagen and related substrates by metal ion/hydrogen peroxide systems

    Hawkins, C L; Davies, Michael Jonathan


    . In this study electron paramagnetic resonance spectroscopy with spin trapping has been used to identify radicals formed on collagen and related materials by metal ion-H2O2 mixtures. Attack of the hydroxyl radical, from a Fe(II)-H2O2 redox couple, on collagen peptides gave signals from both side chain (.CHR...

  15. Interactions between humic acid and hematite and their effects on metal ion speciation.

    Vermeer, A.W.P.


    The impact of toxic chemicals (like metal ions) on the environment is a phenomenon that has been recognised as a mayor problem over the last decades. The speciation of these chemicals determines whether or not a contaminated site has to be regarded as dangerous. The fate of the contaminants depends

  16. Enhancing glycan isomer separations with metal ions and positive and negative polarity ion mobility spectrometry-mass spectrometry analyses

    Zheng, Xueyun; Zhang, Xing; Schocker, Nathaniel S.; Renslow, Ryan S.; Orton, Daniel J.; Khamsi, Jamal; Ashmus, Roger A.; Almeida, Igor C.; Tang, Keqi; Costello, Catherine E.; Smith, Richard D.; Michael, Katja; Baker, Erin S.


    Glycomics has become an increasingly important field of research since glycans play critical roles in biology processes ranging from molecular recognition and signaling to cellular communication. Glycans often conjugate with other biomolecules such as proteins and lipids, and alter their properties and functions, so understanding the effect glycans have on cellular systems is essential. However the analysis of glycans is extremely difficult due to their complexity and structural diversity (i.e., the number and identity of monomer units, and configuration of their glycosidic linkages and connectivities). In this work, we coupled ion mobility spectrometry with mass spectrometry (IMS-MS) to characterize glycan standards and biologically important isomers of synthetic αGal-containing O-glycans including glycotopes of the protozoan parasite Trypanosoma cruzi, which is the causative agent of Chagas disease. IMS-MS results showed significant differences for the glycan structural isomers when analyzed in positive and negative polarity and complexed with different metal cations. These results suggest specific metal ions or ion polarities could be used to target and baseline separate glycan isomers of interest with IMS-MS.

  17. Selective removal of heavy metal ions by disulfide linked polymer networks

    Ko, Dongah; Sung Lee, Joo; Patel, Hasmukh A.


    Heavy metal contaminated surface water is one of the oldest pollution problems, which is critical to ecosystems and human health. We devised disulfide linked polymer networks and employed as a sorbent for removing heavy metal ions from contaminated water. Although the polymer network material has...... a moderate surface area, it demonstrated cadmium removal efficiency equivalent to highly porous activated carbon while it showed 16 times faster sorption kinetics compared to activated carbon, owing to the high affinity of cadmium towards disulfide and thiol functionality in the polymer network. The metal...... sorption mechanism on polymer network was studied by sorption kinetics, effect of pH, and metal complexation. We observed that the metal ions―copper, cadmium, and zinc showed high binding affinity in polymer network, even in the presence of competing cations like calcium in water....

  18. Rare-earth neutral metal injection into an electron beam ion trap plasma

    Magee, E. W., E-mail:; Beiersdorfer, P.; Brown, G. V. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Hell, N. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Dr. Remeis-Sternwarte and ECAP, Universität Erlangen-Nürnberg, 96049 Bamberg (Germany)


    We have designed and implemented a neutral metal vapor injector on the SuperEBIT high-energy electron beam ion trap at the Lawrence Livermore National Laboratory. A horizontally directed vapor of a europium metal is created using a thermal evaporation technique. The metal vapor is then spatially collimated prior to injection into the trap. The source's form and quantity constraints are significantly reduced making plasmas out of metal with vapor pressures ≤10{sup −7} Torr at ≥1000 °C more obtainable. A long pulsed or constant feed metal vapor injection method adds new flexibility by varying the timing of injection and rate of material being introduced into the trap.

  19. Method and apparatus for ion sequestration and a nanostructured metal phosphate

    Mattigod, Shas V.; Fryxell, Glen E.; Li, Xiaohong; Parker, Kent E.; Wellman, Dawn M.


    A nanostructured substance, a process for sequestration of ionic waste, and an ion-sequestration apparatus are disclosed in the specification. The nanostructured substance can comprise a Lewis acid transition metal bound to a phosphate, wherein the phosphate comprises a primary structural component of the substance and the Lewis acid transition metal is a reducing agent. The nanostructured substance has a Brunner-Emmet-Teller (BET) surface area greater than or equal to approximately 100 m.sup.2/g, and a distribution coefficient for an analyte, K.sub.d, greater than or equal to approximately 5000 ml/g. The process can comprise contacting a fluid and a nanostructured metal phosphate. The apparatus can comprise a vessel and a nanostructured metal phosphate. The vessel defines a volume wherein a fluid contacts the nanostructured metal phosphate.

  20. Magnetic field effect in photodetachment from negative ion in electric field near metal surface

    Tang Tian-Tian; Wang De-Hua; Huang Kai-Yun; Wang Shan-Shan


    Based on the closed-orbit theory, the magnetic field effect in the photodetachment of negative ion in the electric field near a metal surface is studied for the first time. The results show that the magnetic field can produce a significant effect on the photodetachment of negative ion near a metal surface. Besides the closed orbits previously found by Du et al. for the H-in the electric field near a metal surface (J. Phys. B 43 035002 (2010)), some additional closed orbits are produced due to the effect of magnetic field. For a given ion-surface distance and an electric field strength, the cross section depends sensitively on the magnetic field strength. As the magnetic field strength is very small, its influence can be neglected. With the increase of the magnetic field strength, the number of the closed orbits increases greatly and the oscillation in the cross section becomes much more complex. Therefore we can control the photodetachment cross section of the negative ion by changing the magnetic field strength. We hope that our results may guide future experimental studies for the photodetachment process of negative ion in the presence of external fields and surfaces.