Ruthenium Tetroxide

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Peter M Elias - One of the best experts on this subject based on the ideXlab platform.

  • membrane structures in normal and essential fatty acid deficient stratum corneum characterization by Ruthenium Tetroxide staining and x ray diffraction
    1991
    Co-Authors: Peter M Elias, Sui Yuen E Hou, Alok K Mitra, Stephen H White, Gopinathan K Menon, Ruby Ghadially
    Abstract:

    Abstract Despite the importance of intercellular lamellar bilayers for stratum corneum (SC) barrier function, knowledge about the structure of these bilayers is limited due to their poor visualization and/or retention. Whereas substitution of Ruthenium Tetroxide (RuO 4 ) for osmium Tetroxide fixation provides clear images of these bilayers, the usefulness of RuO 4 has been limited by its slow penetration and cytotoxicity. Utilizing a new fixation protocol for RuO 4 , we obtained clear images of lamellar domains at all levels of murine SC. Computer-aided image reconstructions demonstrated a lamellar spacing of 129 ± 2 A, which agreed with x-ray diffraction data from parallel, unfixed samples (131 ± 2 A), a spacing not affected by hydration. Furthermore, novel structures were seen in the intercellular spaces of normal SC. Finally, in murine essential fatty acid deficiency (EFAD), the overall lamellar spacing is comparable to normal [127 ± 7 A by computer transform vs. 131.9 ± 2 A (hydrated) and 129.6 ± 2.2 A (dry) by x-ray diffraction]. Yet, these domains are structurally abnormal, displaying regions with either an excess or absence of lamellae. The new RuO 4 protocol provides quantitative information about SC lamellar dimensions and morphologic abnormalities in bilayer distribution and substructure in EFAD stratum corneum that are not detected by either x-ray diffraction or computer-aided image reconstruction. Thus, the barrier abnormality in EFAD stratum corneum can be ascribed either to focal depletion of lamellae or abnormalities in lamellar substructure.

  • avian permeability barrier function reflects mode of sequestration and organization of stratum corneum lipids reevaluation utilizing Ruthenium Tetroxide staining and lipase cytochemistry
    1991
    Co-Authors: Gopinathan K Menon, Sui Yuen E Hou, Peter M Elias
    Abstract:

    Abstract The epidermis of avians and terrestrial mammals has evolved distinct, but related mechanisms to survive in a terrestrial environment. In both phyla, stratum corneum lipids form the basis of the cutaneous permeability barrier, but barrier function is less efficient in avians. Whereas in mammals the epidermal lamellar body (LB) secretes its contents into the intercellular spaces, in the feathered epidermis of avians, its distinctive secretory organelle, the multigranular body (MGB), does not secrete its contents into the stratum corneum intercellular spaces. Yet, neutral lipid-enriched droplets, derived from the cytosolic breakdown of MGB. ultimately are squeezed through membrane pores into the stratum corneum interstices. In this study we determined: a) using Ruthenium Tetroxide (RuO 4 ) fixation, whether these droplets form membrane structures after deposition in the stratum corneum interstices; and b) the similarities and differences between avian MGB and mammalian LB, using enzyme cytochemistry as a marker for secretion, and optical diffraction computer-aided image analysis and reconstruction to compare the internal structure of MGB vs. LB. MGB were shown to possess a similar lamellar substructure to LB in RuO 4 -fixed specimens, exhibiting comparable dimensions on optical diffraction and computer transform analysts. Moreover, the intercellular lipids of avian stratum corneum lacked membrane-substructure, as was present in parallel samples of mammalian stratum corneum. Thus, both the absence of MGB secretion, and the failure of intercellular lipids to form membrane bilayers may explain the inherent differences in barrier function in these two taxa.

Christian Ekberg - One of the best experts on this subject based on the ideXlab platform.

  • Nordisk kernesikkerhedsforskning Norraenar kjarnöryggisrannsóknir Pohjoismainen ydinturvallisuustutkimus Nordisk kjernesikkerhetsforskning Nordisk kärnsäkerhetsforskning Nordic nuclear safety research Interactions of RuO4(g) with different surfaces in nuc
    2020
    Co-Authors: Joachim Holm, Henrik Glänneskog, Christian Ekberg
    Abstract:

    Abstract During a severe nuclear reactor accident with air ingress, Ruthenium in the form of RuO4 can be released from the nuclear fuel. Hence, it is important to investigate how the reactor containment is able to reduce the source term of Ruthenium. This work has investigated the distribution of RuO4 between an aqueous and gaseous phase in the temperature interval of 20-50°C by on-line measurements with an experimental set-up made of glass. The experiments showed that RuO4 is almost immediately distributed in the aqueous phase after its introduction in the set-up in the entire temperature interval. However, the deposition of Ruthenium on the glass surfaces in the system was significant. The speciation of the Ruthenium on the glass surfaces was studied by SEM-EDX and ESCA and was determined to be the expected RuO2. Experiments of interactions between gaseous Ruthenium Tetroxide and the metals aluminium, copper and zinc have been investigated. The metals were treated by RuO4 (g) at room temperature and analyzed with ESCA, SEM and XRD. The analyses show that the black Ruthenium deposits on the metal surfaces were RuO2, i.e. the RuO4 (g) has been transformed on the metal surfaces to RuO2(s). The analyses showed also that there was a significant deposition of Ruthenium Tetroxide especially on the copper and zinc samples. Aluminium has a lower ability to deposit gaseous Ruthenium Tetroxide than the other metals. The conclusion that can be made from the results is that surfaces in nuclear reactor containments will likely reduce the source term in the case of a severe accident in a nuclear power plant. Key words Summary During a severe nuclear reactor accident with air ingress, Ruthenium in the form of RuO 4 can be released from the nuclear fuel. Hence, it is important to investigate how the reactor containment is able to reduce the source term of Ruthenium. This work has investigated the distribution of RuO 4 between an aqueous and gaseous phase in the temperature interval of 20-50°C by on-line measurements with an experimental set-up made of glass. The experiments showed that RuO 4 is almost immediately distributed in the aqueous phase after its introduction in the set-up in the entire temperature interval. However, the deposition of Ruthenium on the glass surfaces in the system was significant. The speciation of the Ruthenium on the glass surfaces was studied by SEM-EDX and ESCA and was determined to be the expected RuO 2 . Experiments of interactions between gaseous Ruthenium Tetroxide and the metals aluminium, copper and zinc have been investigated. The metals were treated by RuO 4 (g) at room temperature and analyzed with ESCA, SEM and XRD. The analyses show that the black Ruthenium deposits on the metal surfaces were RuO 2 , i.e. the RuO 4 (g) has been transformed on the metal surfaces to RuO 2 (s). The analyses showed also that there was a significant deposition of Ruthenium Tetroxide especially on the copper and zinc samples. Aluminium has a lower ability to deposit gaseous Ruthenium Tetroxide than the other metals. The conclusion that can be made from the results is that surfaces in nuclear reactor containments will likely reduce the source term in the case of a severe accident in a nuclear power plant

  • interaction of Ruthenium Tetroxide with iodine covered surfaces of materials in nuclear reactor containment building
    2016
    Co-Authors: Ivan Kajan, Sabrina Tietze, Christian Ekberg
    Abstract:

    Volatile iodine and Ruthenium species are likely to be released from the fuel during a severe nuclear accident. Both iodine and Ruthenium are expected to deposit on the surfaces in the containment building of the nuclear power plant. It is assumed that, due to the different release times from the fuel, Ruthenium will reach the containment at the time when surfaces are already deposited with iodine species. The influence of Ruthenium Tetroxide on elemental iodine-covered surfaces in the containment of nuclear power plants was studied in this work. The ability of Ruthenium Tetroxide to oxidize iodine deposits on zinc, aluminum, copper and epoxy paint at high humidity conditions was evaluated. Quantification of both iodine and Ruthenium deposits was done by the means of gamma spectroscopy. The chemical speciation of deposited elements was observed with SEM, XPS and EDX techniques. Experiments showed that Ruthenium Tetroxide oxidized iodine deposits into the volatile forms of iodine on zinc and aluminum samples and higher iodine oxides in the case of copper and epoxy paint samples. A major increase of Ruthenium uptake on iodine-exposed surfaces in comparison to clean surfaces was observed.

  • Interaction of Ruthenium Tetroxide with surfaces of nuclear reactor containment building
    2016
    Co-Authors: Ivan Kajan, Henric Lasseson, Ingmar Persson, Christian Ekberg
    Abstract:

    AbstractDuring a severe nuclear accident, different fission products will be released from the nuclear fuel and some of them may eventually reach the containment building. Ruthenium is considered to be an important fission product due to the possible formation of volatile oxides. Radiotoxicity and chemical toxicity of the volatile Ruthenium compounds present a considerable hazard during a severe nuclear accident.In this work, experiments regarding behavior of Ruthenium Tetroxide in the reactor containment were performed. The interactions of Ruthenium Tetroxide (RuO4) with zinc, copper, aluminum and epoxy paint in dry and humid atmosphere were examined. SEM/EDX (scanning electron microscope/energy-dispersive X-ray spectroscopy), XPS (X-ray photoelectron spectroscopy) and EXAFS (extended X-ray absorption fine structure) techniques were used to identify the chemical composition of the deposits formed after the interaction of RuO4 with the different materials. Additionally, distribution of Ruthenium between d...

  • Deposition of RuO4 on various surfaces in a nuclear reactor containment
    2009
    Co-Authors: Joachim Holm, Henrik Glänneskog, Christian Ekberg
    Abstract:

    During a severe nuclear reactor accident with air ingress, Ruthenium can be released from the nuclear fuel in the form of Ruthenium Tetroxide. Hence, it is important to investigate how the reactor containment is able to reduce the source term of Ruthenium. The aim of this work was to investigate the deposition of gaseous Ruthenium Tetroxide on aluminium, copper and zinc, which all appear in relatively large amounts in reactor containment. The experiments show that Ruthenium Tetroxide is deposited on all the metal surfaces, especially on the copper and zinc surfaces. A large deposition of Ruthenium Tetroxide also appeared on the relatively inert glass surfaces in the experimental set-ups. The analyses of the different surfaces, with several analytical methods, showed that the form of deposited Ruthenium was mainly Ruthenium dioxide. (C) 2009 Elsevier B.V. All rights reserved.

Laurent Manceron - One of the best experts on this subject based on the ideXlab platform.

  • line intensity measurements and analysis in the ν3 band of Ruthenium Tetroxide
    2018
    Co-Authors: Vander J Auwera, Sebastien Reymondlaruinaz, V Boudon, Denis Doizi, Laurent Manceron
    Abstract:

    Abstract Ruthenium Tetroxide (RuO4) is a heavy tetrahedral molecule characterized by an unusual volatility near ambient temperature. Because of its chemical toxicity and the radiological impact of its 103Ru and 106Ru isotopologues, the possible remote sensing of this compound in the atmosphere has renewed interest in its spectroscopic properties. The present contribution is the first investigation dealing with high-resolution line-by-line intensity measurements for the strong fundamental band observed near 10 μm, associated with the excitation of the infrared active stretching mode ν3. It relies on new, high resolution FTIR spectra recorded at room temperature, using a specially constructed cell and an isotopically pure sample of 102Ru16O4. Relying on an effective Hamiltonian and associated effective dipole moment [S Reymond–Laruinaz et al, J Mol Spectrosc 2015;315:46–54], the measured line intensities were assigned and dipole moment parameters determined. A HITRAN-formatted frequency and intensity line list was generated.

  • line intensity measurements and analysis in the ν 3 band of Ruthenium Tetroxide
    2018
    Co-Authors: Vander J Auwera, Sebastien Reymondlaruinaz, V Boudon, Denis Doizi, Laurent Manceron
    Abstract:

    Abstract Ruthenium Tetroxide (RuO4) is a heavy tetrahedral molecule characterized by an unusual volatility near ambient temperature. Because of its chemical toxicity and the radiological impact of its 103Ru and 106Ru isotopologues, the possible remote sensing of this compound in the atmosphere has renewed interest in its spectroscopic properties. The present contribution is the first investigation dealing with high-resolution line-by-line intensity measurements for the strong fundamental band observed near 10 μm, associated with the excitation of the infrared active stretching mode ν3. It relies on new, high resolution FTIR spectra recorded at room temperature, using a specially constructed cell and an isotopically pure sample of 102Ru16O4. Relying on an effective Hamiltonian and associated effective dipole moment [S Reymond–Laruinaz et al, J Mol Spectrosc 2015;315:46–54], the measured line intensities were assigned and dipole moment parameters determined. A HITRAN-formatted frequency and intensity line list was generated.

  • infrared spectroscopy of Ruthenium Tetroxide and high resolution analysis of the ν3 band
    2015
    Co-Authors: Sebastien Reymondlaruinaz, V Boudon, Laurent Manceron, L Lago, Denis Doizi
    Abstract:

    Abstract RuO 4 is a heavy tetrahedral molecule which has practical uses for several industrial fields. Due to its chemical toxicity and the radiological impact of its 103 and 106 isotopologues, the possible remote sensing of this compound in the atmosphere has renewed interest in its spectroscopic properties. New, higher resolution FTIR spectra have been recorded at room temperature, using an isotopic pure sample of 102 RuO 4 and a sample with all stable isotopes present in natural abundance. We reinvestigate here the strong ν 3 stretching fundamental region and perform new assignments and effective Hamiltonian parameter fits for the five main isotopologues ( 99 RuO 4 , 100 RuO 4 , 101 RuO 4 , 102 RuO 4 and 104 RuO 4 ), by considering the ν 3 stretching mode as an isolated band. We provide precise effective Hamiltonian parameters, including band centers and Coriolis interaction parameters. We discuss isotopic shifts and estimate the band centers for the two minor isotopologues ( 97 RuO 4 and 98 RuO 4 ) and the two radioactive isotopologues ( 103 RuO 4 and 106 RuO 4 ). Experimental band strengths for the two IR active fundamentals are also reported for the first time.

Vincenzo Piccialli - One of the best experts on this subject based on the ideXlab platform.

  • Ruthenium Tetroxide and perruthenate chemistry recent advances and related transformations mediated by other transition metal oxo species
    2015
    Co-Authors: Vincenzo Piccialli
    Abstract:

    In the last years Ruthenium Tetroxide is increasingly being used in organic synthesis. Thanks to the fine tuning of the reaction conditions, including pH control of the medium and the use of a wider range of co-oxidants, this species has proven to be a reagent able to catalyse useful synthetic transformations which are either a valuable alternative to established methods or even, in some cases, the method of choice. Protocols for oxidation of hydrocarbons, oxidative cleavage of C-C double bonds, even stopping the process at the aldehyde stage, oxidative cleavage of terminal and internal alkynes, oxidation of alcohols to carboxylic acids, dihydroxylation of alkenes, oxidative degradation of phenyl and other heteroaromatic nuclei, oxidative cyclization of dienes, have now reached a good level of improvement and are more and more included into complex synthetic sequences. The perruthenate ion is a Ruthenium (VII) oxo-species. Since its introduction in the mid-eighties, tetrapropylammonium perruthenate (TPAP) has reached a great popularity among organic chemists and it is mostly employed in catalytic amounts in conjunction with N-methylmorpholine N-oxide (NMO) for the mild oxidation of primary and secondary alcohols to carbonyl compounds. Its use in the oxidation of other functionalities is known and recently, its utility in new synthetic transformations has been demonstrated. New processes, synthetic applications, theoretical studies and unusual transformations, published in the last eight years (2006-2013), in the chemistry of these two oxo-species, will be covered in this review with the aim of offering a clear picture of their reactivity. When appropriate, related oxidative transformations mediated by other metal oxo-species will be presented to highlight similarities and differences. An historical overview of some aspects of the Ruthenium Tetroxide chemistry will be presented as well.

  • oxidative cyclization of dienes and polyenes mediated by transition metal oxo species
    2007
    Co-Authors: Vincenzo Piccialli
    Abstract:

    During the last forty years, several groups have reported results concerning the oxidative cyclization of polyenes, mostly dienes, with transition-metal-oxo species such as permanganate, Ruthenium Tetroxide, perruthenate and osmium Tetroxide, but only recently has a systematic study of some of these processes been undertaken. The formation in a single step of tetrahydrofuran, poly-tetrahydrofuran, tetrahydropyran and oxepane products with complete relative stereocontrol, and the unique postulated mechanisms, render these processes very appealing from both the synthetic and theoretical points of view. Recent synthetic applications of these oxidative transformations have highlighted their usefulness. This review summarizes the state of the art in this field, in an attempt to provide a comprehensive view of these processes. Some similarities between the chemistry of Ruthenium Tetroxide and rhenium(VII)-oxo species are highlighted. 1 Introduction 2 Formation of Tetrahydrofurans 2.1 Permanganate-Mediated Cyclization of 1,5-Dienes 2.2 Ruthenium Tetroxide Catalyzed Cyclization of 1,5-Dienes 2.2.1Synthetic Applications of Ruthenium Tetroxide Catalyzed Cyclization of 1,5-Dienes 2.3 Perruthenate-Catalyzed Cyclization of 1,5-Dienes 2.4 Osmium Tetroxide Catalyzed Cyclization of 1,4- and 1,5-Dienes 3 Osmium Tetroxide Catalyzed Formation of Tetrahydrofurans from Alkenediols 4 Osmium Tetroxide Catalyzed Formation of Pyrrolidines 5 Chromium(VI)-Mediated Formation of Tetrahydrofurans from Alkenediols 6 Formation of Tetrahydropyrans 6.1 Ruthenium Tetroxide Catalyzed Cyclization of 1,6-Dienes 6.2 Permanganate-Mediated Cyclization of 1,6-Dienes 7 Ruthenium Tetroxide Catalyzed Formation of Oxepanes from 1,7-Dienes 8 Ruthenium Tetroxide and Permanganate-Mediated Formation of Oxiranes from 1,3-Dienes 9 Ruthenium Tetroxide Catalyzed Oxidative Polycyclization 10 Conclusions

G Eglinton - One of the best experts on this subject based on the ideXlab platform.

  • a much modified and miniaturised chemical degradation procedure for the analysis of both simple organic compounds and biologically derived macromolecules Ruthenium Tetroxide oxidation
    1992
    Co-Authors: G Standen, G Eglinton
    Abstract:

    Abstract A simplified and miniaturised Ruthenium Tetroxide (RuO4) oxidation procedure, able to cope with tens of samples simultaneously, was subjected to a detailed evaluation. All the modifications were rigorously tested. Experiments employing different combinations of co-oxidant and catalyst permitted periodic acid and RuO4 reagents to be selected on their overall proficiencies. Investigations into the effects of changing co-oxidant (to total organic carbon) ratio, time and temperature were performed on two kerogens, initially. A co-oxidant ratio of 50:1 (excess) was chosen, with a temperature of 35°C to reduce absolute reaction times to ∼24 hr, without adversely affecting product yields. Various common esterification procedures were applied. Acid catalysed methylation (1.5% sulphuric acid and 5% tetrahydrofuran in methanol) was found to give superior yields of esterified products. Substitution of existing internal standards with more representative ones, notably 2-octadecylbutanedioic acid, and their incorporation into the reaction medium, enabled a more accurate mass balance to be made. In addition, standard compounds were oxidised to endorse the reaction. Tests with regard to the minimum working limit (TOC) were accomplished down to ∼ 1 mg. Herein is demonstrated a greatly refined RuO4 oxidation system.

  • Ruthenium Tetroxide oxidation of natural organic macromolecules messel kerogen
    1991
    Co-Authors: G Standen, R J Boucher, J Rafalskabloch, G Eglinton
    Abstract:

    Abstract Molecular characterisation of Messel kerogen was undertaken using selective chemical degradation with Ruthenium Tetroxide (RuO 4 ). Eight degradation experiments were performed utilising co-oxidant/substrate (c/s) ratios (weight for (weight for weight (w/w) based upon a Total Organic Carbon (TOC) content of 53.5% for the kerogen concentrate) of 4:1, 8:1, 12:1, 16:1, 20:1, 30:1, 40:1, and 50:1 at a temperature of 25°C. Two further experiments were executed using a temperature of 35°C and c/s ratios (w/w based on TOC) of 4:1 and 16:1; the products were extracted from the former reaction and more co-oxidant added (16:1) to continue the oxidation. It was discovered that a high (20:1 and above) c/s ratios yields a high percentage of organic solvent extract and an increase in temperature liberates more products from the lower c/s ratio reaction mixtures more rapidly. For these reasons, Ruthenium Tetroxide completely oxidises (> 95%) the kerogen matrix at elevated (> 20:1) co-oxidant concentrations. Affects of time on the reaction (with an excess (50:1) of cooxidant and a temperature of 25°C) were also investigated; temperature and time appear to be inversely proportional to each another and directly affect reaction rates without significantly altering the products. Solvent-soluble extracts were dominated by two homologous series of acids: straight chain monocarboxylic acids (mono' acids) and α,ω-dicarboxylic acids (di' acids) (C 4 C 30 ) indicating that polymethylene chains are important constituents of Messel kerogen. Of lesser importance was a series of acyclic isoprenoid acids (C 13 C 17 ) and C 19 C 21 ), and minor series of branched mono' (C 13 C 17 ), branched di' (C 5 C 11 ) and hopanoic' (C 30 C 32 ) acids. This method provides valuable compositional information about the aliphatic and alicyclic portions of the kerogen. From these results, Messel kerogen appears to be a mixed type I and type II kerogen which can then be definitely classified as a type II on a van Krevelen diagram.

  • molecular characterization of kerogens by mild selective chemical degradation Ruthenium Tetroxide oxidation
    1991
    Co-Authors: R J Boucher, G Standen, G Eglinton
    Abstract:

    Abstract Molecular characterization of two kerogen isolates (Messel and Kimmeridge Clay), two kerogen-rich shales (Green River and Maoming) and a coal, (Loy Yang) was undertaken using selective chemical degradation with Ruthenium Tetroxide (RuO4). The RuO4 oxidation gave extracts which were soluble in dichloromethane and contained series of straight chain monocarboxylic acids, α,ω-dicarboxylic acids, branched mono- and dicarboxylic acids, isoprenoid and cyclic acids. Straight chain carboxylic acids were predominant (65–87% of quantified chromatogram components for the range of sedimentary organic matter studied), reflecting the major content of polymethylene chains in these kerogens. This mild, oxidative technique serves to differentiate kerogens at a molecular level, thereby supplementing existing conventional chemical, pyrolytic, n.m.r. and other techniques.