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Sample records for bulky rhodium intercalators

  1. One-step synthesis of layered yttrium hydroxides in immiscible liquid–liquid systems: Intercalation of sterically-bulky hydrophobic organic anions and doping of europium ions

    International Nuclear Information System (INIS)

    Inorganic–organic layered rare-earth compounds were synthesized on the basis of a biphasic liquid–liquid system in one pot. Layered yttrium hydroxides (LYHs) were chosen as a host material for the intercalation of hydrophobic organic guest anions such as benzoate, sebacate, or laurate. In a typical synthesis, an organic phase dissolving carboxylic acid was placed in contact with an equal amount of an aqueous phase dissolving yttrium nitrate n-hydrate and urea. At elevated temperatures up to 80 °C, urea was hydrolyzed to release hydroxyl anions which were used to form yttrium hydroxide layers. LYHs were then precipitated with the intercalation of carboxylate anions delivered from the organic phase under the distribution law. The structure and the morphology of the LYHs could be modulated by the intercalated anions. Doped with Eu3+ ions, the LYHs exhibited red photoluminescence which was enhanced by the intercalated anions due to the antenna effect. - Graphical abstract: The Eu3+-doped layered yttrium hydroxide exhibits intense red photoluminescence after intercalation of benzoate ions. Display Omitted - Highlights: • Immiscible biphasic liquid systems were introduced to synthesize layered yttrium hydroxides. • The temperature of the biphasic systems does not exceed 80 °C in one step of the synthesis. • Hydrophobic organic anions were intercalated between the hydroxide layers in one pot. • Structure and morphology of the hydroxides were modulated by changing the kind of organic anions. • Eu3+-doping led to red luminescence from the hydroxides in association with the intercalated organic anions

  2. Measuring bulky waste arisings in Hong Kong

    International Nuclear Information System (INIS)

    All too often, waste authorities either assume that they know enough about their bulky waste stream or that it is too insignificant to deserve attention. In this paper, we use Hong Kong as an example to illustrate that official bulky waste figures can actually be very different from the reality and therefore important waste management decisions made based on such statistics may be wrong too. This study is also the first attempt in Hong Kong to outline the composition of bulky waste. It was found that about 342 tonnes/day of wood waste were omitted by official statistics owing to incomplete records on actual bulky waste flow. This is more than enough to provide all the feedstock needed for one regular-sized wood waste recycling facility in Hong Kong. In addition, the proportion of bulky waste in the municipal solid waste (MSW) streams in Hong Kong should be about 6.1% instead of the officially stated 1.43%. Admittedly, there are limitations with this study. Yet, present findings are suggestive of significant MSW data distortion in Hong Kong.

  3. Harnessing DNA intercalation.

    Science.gov (United States)

    Persil, Ozgül; Hud, Nicholas V

    2007-10-01

    Numerous small molecules are known to bind to DNA through base pair intercalation. Fluorescent dyes commonly used for nucleic acid staining, such as ethidium, are familiar examples. Biological and physical studies of DNA intercalation have historically been motivated by mutation and drug discovery research. However, this same mode of binding is now being harnessed for the creation of novel molecular assemblies. Recent studies have used DNA scaffolds and intercalators to construct supramolecular assemblies that function as fluorescent 'nanotags' for cell labeling. Other studies have demonstrated how intercalators can be used to promote the formation of otherwise unstable nucleic acid assemblies. These applications illustrate how intercalators can be used to facilitate and expand DNA-based nanotechnology. PMID:17825446

  4. Bulky waste quantities and treatment methods in Denmark

    DEFF Research Database (Denmark)

    Larsen, Anna Warberg; Petersen, Claus; Christensen, Thomas Højlund

    2012-01-01

    Bulky waste is a significant and increasing waste stream in Denmark. However, only little research has been done on its composition and treatment. In the present study, data about collection methods, waste quantities and treatment methods for bulky waste were obtained from two municipalities. In...... addition a sorting analysis was conducted on combustible waste, which is a major fraction of bulky waste in Denmark. The generation of bulky waste was found to be 150–250 kg capita−1 year−1, and 90% of the waste was collected at recycling centres; the rest through kerbside collection. Twelve main fractions...

  5. Rhodium and silicon system: II. Rhodium silicide formation

    International Nuclear Information System (INIS)

    Detailed characterizations of rhodium/silicon films prepared by co-deposition using magnetron sputtering have been carried out on silicon substrates at room temperature up to 900 deg. C. The properties of the films were investigated using XPS/UPS, XRD, SIMS, SEM and AFM techniques. It should be emphasized that XPS/UPS measurements are carried out without breaking the vacuum to avoid any contamination of the film. Up to 500 deg. C an interdiffusion between the oxidized silicon wafer and the deposited Rh/Si film occurred leading to hole formation in the entire film at 900 deg. C. Diffraction patterns for the compounds Rh2Si, Rh5Si3, RhSi and Rh3Si4 were measured. Upon annealing the covalent character is increased and for the samples forming the compound RhSi the valence band structure is markedly changed. Depth profiling (XPS and SIMS) reveals a stable composition in the bulk of the film. For these measurements the silicon-rich alloy in the interfacial layer is probably an effect of sputtering, by implanting the Rh atoms into the silicon substrate. A previously reported negative shift for the compound Rh5Si3 could be connected to the sample preparation, as sputtering of the surface is reducing the silicon content and inducing a glassy state. For the first phase Rh2Si formed on the rhodium-rich side the shift in binding energy is unclear, for all the other compounds encountered in this work a positive shift relative to pure rhodium was found.

  6. Study on the Recovery of Rhodium from Spent Organic Rhodium Catalysts of Acetic Acid Industry Using Pyrometallurgical Process

    Institute of Scientific and Technical Information of China (English)

    HE Xiaotang; WANG Huan; WU Xilong; LI Yong; ZHAO Yu; HAN Shouli; LI Kun; GUO Junmei

    2012-01-01

    A new process recycling rhodium from organic waste containing rhodium in acetic acid industry is developed.Use the special affinity of base metal sulfides (FeS,Ni2S3,CuS,etc.) on platinum group metals,adopting high nickel matte trapping-aluminothermic activation method to recovery rhodium from incinerator residue of organic rhodium waste.The method is shorter process,lower equipment requirement,and the higher activity of rhodium black.In pyrometallurgy enrichment process,the recovery rate of rhodium reached 94.65%,the full flow of rhodium recovery rate was 92.04%.

  7. Graphite intercalation compounds and applications

    CERN Document Server

    Enoki, Toshiaki; Endo, Morinobu

    2003-01-01

    1. Introduction. 2. Synthesis and Intercalation Chemistry. 3. Structures and Phase Transitions. 4. Lattice Dynamics. 5. Electronic Structures. 6. Electron Transport Properties. 7. Magnetic Properties. 8. Surface Properties and Gas Adsorption. 9. GICs and Batteries. 10. Highly Conductive Graphite Fibers. 11. Exfoliated Graphite Formed by Intercalation. 12. Intercalated Fullerenes and Carbon Nanotubes. Index

  8. Rhodium(I) catalysis in olefin photoreactions

    International Nuclear Information System (INIS)

    The photorearrangement (254 nm) of 1,5-cyclooctadiene (1) in the presence of rhodium(I) chloride to give 1,4-cyclooctadiene (4) was found by deuterium labeling to involve an intramolecular [1,3] shift of hydrogen. A rate-determining cleavage of an allylic C--H bond is indicated by a deuterium isotope effect, k/sub H//k/sub D/ = 1.55 +- 0.03 for the 1 → 4 rearrangement. The acyclic 1,5-diene, 3,3-dimethyl-1,5-hexadiene (8), rearranges in the presence of rhodium(I) chloride upon uv irradiation (254 nm) to give cis-3,3-dimethyl-1,4-hexadiene (10) and the trans isomer 11 in a 1:4 ratio, respectively. This observation supports a mechanism for the photorearrangement of olefins catalyzed by rhodium(I) involving an initial photodissociation of one of two rhodium(I) coordinated carbon-carbon double bonds. This results in an increase in the coordinative unsaturation of rhodium(I) and enhances the proclivity of this d/sub s/ metal atom toward oxidative addition of an allylic C--H bond. A eta3-allylrhodium hydride intermediate then gives rearranged olefin by reductive elimination. Lastly, a novel photochemical, rhodium(I) catalyzed hydrogen transfer is reported which gives cyclooctene (7) from cyclooctadienes under unprecedentedly mild conditions. (auth)

  9. Intercalation Assembly Method and Intercalation Process Control of Layered Intercalated Functional Materials

    Institute of Scientific and Technical Information of China (English)

    LI Kaitao; WANG Guirong; LI Dianqing; LIN Yanjun; DUAN Xue

    2013-01-01

    Layered intercalated functional materials of layered double hydroxide type are an important class of functional materials developed in recent years.Based on long term studies on these materials in the State Key Laboratory of Chemical Resource Engineering in Beijing University of Chemical Technology,the principle for the design of controlled intercalation processes in the light of future production processing requirements has been developed.Intercalation assembly methods and technologies have been invented to control the intercalation process for preparing layered intercalated materials with various structures and functions.

  10. Intercalating oleylamines in graphite oxide.

    Science.gov (United States)

    Yang, Kaikun; Liang, Si; Zou, Lianfeng; Huang, Liwei; Park, Cheol; Zhu, Lisheng; Fang, Jiye; Fu, Qiang; Wang, Howard

    2012-02-01

    Graphite oxide has been synthesized from raw graphite particles and been treated with various mass amounts of oleylamine as intercalants to form intercalation compounds. X-ray diffraction patterns reveal that the inter-sheet distances strongly depend on the graphite oxide to oleylamine mass ratios. The equilibrium-like behavior implies diffusion-dominated oleylamine adsorption on graphite oxide in solution and excluded volume intercalations among oleylamine-adsorbed graphite oxide during restacking. The intercalation compounds are soluble in organic solvents, and their applications in the fabrication of transparent and conductive coatings have been demonstrated. PMID:22229856

  11. Chemical modification of niobium layered oxide by tetraalkylammonium intercalation

    International Nuclear Information System (INIS)

    Chemical modification of the layered K4Nb6O17 material was systematically investigated through the reaction of its proton-exchanged form (H2K2Nb6O17) in alkaline solutions containing tetramethylammonium (tma+), tetraethylammonium (tea+) or tetrapropylammonium (tpa+) cations. The intercalated amount reaches 50% (for tma+), 25% (for tea+) and 15% (for tpa+) of the H2K2Nb6O17 negative charge (concerning the exchange at interlayer I) due to the steric hindrance of larger cations. Hexaniobate samples present (020) basal reflections equal to 23.0, 26.3 and 26.5 A once intercalated respectively with tma+, tea+ and tpa+. When samples are heated above 200-250 deg C, CO2 evolution is observed; Hofmann elimination reaction is also detected for hexaniobate-tpa+ samples. Scanning electron microscopy images show the predominance of plate-like particles; stick-like particles are also observed for samples containing bulky ions. The intercalation reaction is promoted in the order tma+ > tea+ > tpa+, while the formation of a dispersion of colloidal particles is facilitated in the inverse order. (author)

  12. Intercalation Behavior of Barium Phenylphosphonate

    Czech Academy of Sciences Publication Activity Database

    Beneš, L.; Melánová, Klára; Svoboda, Jan; Zima, Vítězslav

    Beijing: Tsinghua University, Beijing, China, 2009. s. 71-71. [15th International Symposium on Intercalation Compounds. 11.05.2009-15.05.2009, Beijing] R&D Projects: GA ČR(CZ) GA203/08/0208 Institutional research plan: CEZ:AV0Z40500505 Keywords : intercalation Subject RIV: CA - Inorganic Chemistry

  13. Solid state phase detector replaces bulky transformer circuit

    Science.gov (United States)

    Moberly, C. L.

    1967-01-01

    Miniature solid state phase detector using MOSFETs is used in a phase lock loop with a sun-bit detector in an integrated data-link circuit. This replaces bulky transformer circuits. It uses an inverter amplifier, a modulator switch, and a buffer amplifier.

  14. The first (tricarbollide)rhodium halide complexes

    Czech Academy of Sciences Publication Activity Database

    Loginov, D.A.; Starikova, ZA.; Petrovskii, PV.; Holub, Josef; Kudinov, AR.

    2011-01-01

    Roč. 14, č. 1 (2011), s. 313-315. ISSN 1387-7003 R&D Projects: GA MŠk LC523 Institutional research plan: CEZ:AV0Z40320502 Keywords : boranes * metallacarboranes * rhodium * tricarbollide Subject RIV: CA - Inorganic Chemistry Impact factor: 1.972, year: 2011

  15. Rhodium-Catalyzed Decarbonylation of Aldoses

    DEFF Research Database (Denmark)

    Monrad, Rune; Madsen, Robert

    2007-01-01

    A catalytic procedure is described for decarbonylation of unprotected aldoses to afford alditols with one less carbon atom. The reaction is performed with the rhodium complex Rh(dppp)2Cl in a refluxing diglyme - DMA solution. A slightly improved catalyst turnover is observed when a catalytic amount...

  16. DPZ-1M rhodium neutron detector performance

    International Nuclear Information System (INIS)

    The characteristics of the DPZ-1M rhodium self-powered neutron detector based on the calculational technique using corrected experimental data are given. These detectors are used for power distribution monitoring in the WWER reactors. For calculating neutron absorption in an emitter incident neutron flux is specified, while the probability of β-particles escape is determined on the base of empirical dependence of extrapolated electron path on its energy. In addition correction by the emither radius of the probability distribution of β-particles escape by experimental data is performed. The results obtained permit to conclude that the rhodium detector possesses high sensitivity to epithermal neutrons Which depends on the neutron spectrum form; current relation of burned-up and non burned- up detector seightly depends on the spectrum form, neutron gas temperature and average neutron spectral hardness

  17. Interaction of hydrogen with samaria supported rhodium catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Bernal, S.; Botana, F.J.; Calvino, J.J.; Cifredo, G.A.; Rodriguez-Izquierdo, J.M.

    1991-01-01

    Hydrogen chemisorption on several samaria supported rhodium catalysts has been studied. The TPD diagrams were broad and rather complex. Adsorption on both, rhodium and support phases was observed. The occurrence of spill over, as well as of metal decoration phenomena, restricts very much the use of apparent H/Rh data to estimate metallic dispersions.

  18. Interaction of hydrogen with samaria supported rhodium catalysts

    International Nuclear Information System (INIS)

    Hydrogen chemisorption on several samaria supported rhodium catalysts has been studied. The TPD diagrams were broad and rather complex. Adsorption on both, rhodium and support phases was observed. The occurrence of spill over, as well as of metal decoration phenomena, restricts very much the use of apparent H/Rh data to estimate metallic dispersions

  19. Rhodium trichloride as a homogeneous catalyst for isotopic hydrogen exchange

    International Nuclear Information System (INIS)

    The use of rhodium trichloride as a homogeneous catalyst for the exchange of aromatic compounds and alkanes is described; comparison of the results with corresponding data from heterogeneous rhodium metal and other homogeneous systems, e.g., platinum and iridium, supports the proposal that specific type of π-complex mechanisms are common to all such exchange systems. (author)

  20. Bulky mediastinal aspergillosis mimicking cancer in an immunocompetent patient.

    Science.gov (United States)

    Stern, Jean-Baptiste; Wyplosz, Benjamin; Validire, Pierre; Angoulvant, Adela; Fregeville, Aude; Caliandro, Raffaele; Gossot, Dominique

    2014-10-01

    We describe the case of a previously healthy 42-year-old woman who presented with a chronic cough and occasional night sweats. Radiologic exploration showed a bulky mediastinal mass surrounding the aortic arch, associated with a left subclavicular lymph node and a cerebral round lesion, mimicking a disseminated lung cancer. Surgical left subclavicular and computed tomography-guided mediastinal biopsy specimens showed granulomatous patterns. Mycologic culture of both samples grew Aspergillus flavus. Resolution was obtained after 9 months of oral voriconazole therapy. PMID:25282220

  1. Photoelectron Spectroscopy of Intercalation Phases

    OpenAIRE

    Wu, Qi-Hui

    2003-01-01

    V2O5 and LiMn2O4 are promising cathode materials for lithium-ion batteries due to their high capacities and battery voltages. The several work was mainly focused on the study of electrochemical and structural properties during lithium intercalation. But there is no detailed knowledge of the changes in electronic structure and the intercalation mechanism itself. Especially no general agreement has been reached on the nature and the extent of the interactions between host material and alkali gu...

  2. Contrast and dose with molybdenum, molybdenum-rhodium, and rhodium-rhodium target-filter combinations in mammography

    International Nuclear Information System (INIS)

    Molybdenum target-molybdenum filter (Mo-Mo) source assemblies are commonly used for screen-film mammography and produce spectra rich in bremsstrahlung between 15 and 20 keV, and molybdenum characteristic x-rays (Kα = 17.5 keV and Kβ = 19.6 keV) that are, optimal for imaging a large segment of patients. With the normal variability of breast size and tissue composition that occurs in the population, Mo-Mo spectra are not always optimal, however. Particularly for thick, fibroglandular breast tissue, higher energy spectra are required, and are achieved to a limited degree by operating Mo-Mo tubes at higher tube potentials. At these higher tube potentials (28-31 kVp), the spectrum exiting the breast has a large contribution from bremsstrahlung of more than 23 keV. Most of the lower energy photons, including the molybdenum characteristic x-rays, are absorbed and result in a higher average tissue dose than is necessary. Incident spectra with x-ray energies in the 20-23 keV range are preferable. Such spectra have been realized with higher atomic number materials, such as rhodium (Rh), used for the anode or k-edge filter. The higher K-absorption edge of rhodium allows transmission of bremsstrahlung in the 20-23.2 keV range, and at a given kilovoltage the Rh-Rh combination results in a more penetrating beam than either Mo-Mo or Mo-Rh (molybdenum x-ray tube anode with rhodium K-edge filter) because of the difference in energy between the rhodium and molybdenum characteristic x-rays. The greater penetrating power of these spectra results in decreased entrance skin exposure and average glandular dose to the breast than with the conventional Mo-Mo spectra. However, associated with this can be a reduction in subject contrast in the mammogram. The objective of this study was to compare the contrast and dose produced with the three source assemblies as a function of x-ray tube potential, breast thickness, and breast parenchymal composition

  3. Superconductivity in graphite intercalation compounds

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Robert P. [Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Weller, Thomas E.; Howard, Christopher A. [Department of Physics & Astronomy, University College of London, Gower Street, London WCIE 6BT (United Kingdom); Dean, Mark P.M. [Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, NY 11973 (United States); Rahnejat, Kaveh C. [Department of Physics & Astronomy, University College of London, Gower Street, London WCIE 6BT (United Kingdom); Saxena, Siddharth S. [Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Ellerby, Mark, E-mail: mark.ellerby@ucl.ac.uk [Department of Physics & Astronomy, University College of London, Gower Street, London WCIE 6BT (United Kingdom)

    2015-07-15

    Highlights: • Historical background of graphite intercalates. • Superconductivity in graphite intercalates and its place in the field of superconductivity. • Recent developments. • Relevant modeling of superconductivity in graphite intercalates. • Interpretations that pertain and questions that remain. - Abstract: The field of superconductivity in the class of materials known as graphite intercalation compounds has a history dating back to the 1960s (Dresselhaus and Dresselhaus, 1981; Enoki et al., 2003). This paper recontextualizes the field in light of the discovery of superconductivity in CaC{sub 6} and YbC{sub 6} in 2005. In what follows, we outline the crystal structure and electronic structure of these and related compounds. We go on to experiments addressing the superconducting energy gap, lattice dynamics, pressure dependence, and how these relate to theoretical studies. The bulk of the evidence strongly supports a BCS superconducting state. However, important questions remain regarding which electronic states and phonon modes are most important for superconductivity, and whether current theoretical techniques can fully describe the dependence of the superconducting transition temperature on pressure and chemical composition.

  4. Superconductivity in graphite intercalation compounds

    International Nuclear Information System (INIS)

    Highlights: • Historical background of graphite intercalates. • Superconductivity in graphite intercalates and its place in the field of superconductivity. • Recent developments. • Relevant modeling of superconductivity in graphite intercalates. • Interpretations that pertain and questions that remain. - Abstract: The field of superconductivity in the class of materials known as graphite intercalation compounds has a history dating back to the 1960s (Dresselhaus and Dresselhaus, 1981; Enoki et al., 2003). This paper recontextualizes the field in light of the discovery of superconductivity in CaC6 and YbC6 in 2005. In what follows, we outline the crystal structure and electronic structure of these and related compounds. We go on to experiments addressing the superconducting energy gap, lattice dynamics, pressure dependence, and how these relate to theoretical studies. The bulk of the evidence strongly supports a BCS superconducting state. However, important questions remain regarding which electronic states and phonon modes are most important for superconductivity, and whether current theoretical techniques can fully describe the dependence of the superconducting transition temperature on pressure and chemical composition

  5. Relaxation of polarized nuclei in superconducting rhodium

    DEFF Research Database (Denmark)

    Knuuttila, T.A.; Tuoriniemi, J.T.; Lefmann, K.

    2000-01-01

    Nuclear spin lattice relaxation rates were measured in normal and superconducting (sc) rhodium with nuclear polarizations up to p = 0.55. This was sufficient to influence the sc state of Rh, whose T, and B-c, are exceptionally low. Because B-c << B-loc and the short-range spin-spin interaction is...... unchanged, the nuclear spin entropy was fully sustained across the sc transition. The relaxation in the sc state was slower at all temperatures without the coherence enhancement close to T-c. Nonzero nuclear polarization strongly reduced the difference between the relaxation rates in the sc and normal...

  6. Characterization of adsorbed dicarbonyls of rhodium

    International Nuclear Information System (INIS)

    We have studies the adsorbed states of CO on dispersed RH in Y zeolites by solid-state 13C NMR spectroscopy. The structure of the dicarbonyl form of adsorbed rhodium has been revealed using a Carr-Purcell-Meiboom-Gill multiple pulse sequence. NMR lineshape calculations show that adsorbed Rh(CO)2 species are undergoing a 180 deg. flipping motion about the C2 axis which bisects the C-Rh-C angle. Spectra calculated with this motional model have been compared with published spectra of CO on Rh-Y zeolites. (author). 7 refs.; 3 figs

  7. Oxidation of Isoeugenol by Salen Complexes with Bulky Substituents

    Directory of Open Access Journals (Sweden)

    Anika Salanti

    2010-03-01

    Full Text Available The catalytic properties of bulky water-soluble salen complexes in the oxidation of isoeugenol(2-methoxy-4-(1-propenyl phenol have been investigated in aqueous ethanol solutions in order to obtain a mixture of polymeric compounds through dehydrogenative polymerization. The average molecular weight of dehydrogenated polymers (DHPs was monitored by GPC and correlated to reaction conditions such as time, concentration of substrate, concentration of catalyst, type of oxidation agent, etc. The DHP synthesized by adopting the best reaction conditions was characterized by different analytical techniques (GPC, 13C-NMR, 31P-NMR and LC-MS to elucidate its structure. The lignin-like polymer resulting from isoeugenol radical coupling possesses valuable biological activity and finds applications in a variety of fields, such as packaging industry and cultural heritage conservation.

  8. Structural properties of small rhodium clusters

    Energy Technology Data Exchange (ETDEWEB)

    Soon, Yee Yeen; Yoon, Tiem Leong [School of Physics, Universiti Sains Malaysia, 11800 USM, Penang (Malaysia); Lim, Thong Leng [Faculty of Engineering and Technology, Multimedia University, Melaka Campus, 75450 Melaka (Malaysia)

    2015-04-24

    We report a systematic study of the structural properties of rhodium clusters at the atomistic level. A novel global-minimum search algorithm, known as parallel tempering multicanonical basin hopping plus genetic algorithm (PTMBHGA), is used to obtain the geometrical structures with lowest minima at the semi-empirical level where Gupta potential is used to describe the atomic interaction among the rhodium atoms. These structures are then re-optimized at the density functional theory (DFT) level with exchange-correlation energy approximated by Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA). The structures are optimized for different spin multiplicities. The ones with lowest energies will be taken as ground-state structures. In most cases, we observe only minor changes in the geometry and bond length of the clusters as a result of DFT-level re-optimization. Only in some limited cases, the initial geometries obtained from the PTMBHGA are modified by the re-optimization. The variation of structural properties, such as ground-state geometry, symmetry and binding energy, with respect to the cluster size is studied and agreed well with other results available in the literature.

  9. Structural properties of small rhodium clusters

    International Nuclear Information System (INIS)

    We report a systematic study of the structural properties of rhodium clusters at the atomistic level. A novel global-minimum search algorithm, known as parallel tempering multicanonical basin hopping plus genetic algorithm (PTMBHGA), is used to obtain the geometrical structures with lowest minima at the semi-empirical level where Gupta potential is used to describe the atomic interaction among the rhodium atoms. These structures are then re-optimized at the density functional theory (DFT) level with exchange-correlation energy approximated by Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA). The structures are optimized for different spin multiplicities. The ones with lowest energies will be taken as ground-state structures. In most cases, we observe only minor changes in the geometry and bond length of the clusters as a result of DFT-level re-optimization. Only in some limited cases, the initial geometries obtained from the PTMBHGA are modified by the re-optimization. The variation of structural properties, such as ground-state geometry, symmetry and binding energy, with respect to the cluster size is studied and agreed well with other results available in the literature

  10. Preparation and Properties of Phenolic Resin/Montmorillonite Intercalation Nanocomposites

    Institute of Scientific and Technical Information of China (English)

    YU Jian-ying; WEI Lian-qi; CAO Xian-kun

    2003-01-01

    Phenolic resin/ montmorillonite intercalation composites were prepared by using the methods of pressing intercalation and melt intercalation. Properties and structure of the composites were investigated by using XRD , TG and test of softening point. It is indicated that both the pressing intercalation and melt intercalation can be used to prepare the phenolic resin/organo-montmorillonite intercalation nanocomposites. Compared with phenolic resin, the intercalation nanocomposites have better heat-resistance, higher decomposition temperatures and less thermal weight-loss. However , these two intercalation methods have different effects on the softening point of the intercalation nanocomposites . Pressing intercalation almost does not affect the softening point of the intercalation nanocomposites, while melt intercalation signifwantly increases the softening point of the intercalation nanocomposites ,probably due to the chemical actions happening in the process of melt intercalation.

  11. Intercalation behavior of barium phenylphosphonate

    Czech Academy of Sciences Publication Activity Database

    Beneš, L.; Melánová, Klára; Svoboda, Jan; Zima, Vítězslav

    2010-01-01

    Roč. 71, č. 4 (2010), s. 530-533. ISSN 0022-3697. [15th International Symposium on Intercalation Compounds. Beijing, 11.05.2009-15.05.2009] R&D Projects: GA ČR GA203/08/0208 Institutional research plan: CEZ:AV0Z40500505 Keywords : inorganic compounds * organic compounds * X-ray diffraction Subject RIV: CA - Inorganic Chemistry Impact factor: 1.384, year: 2010

  12. Aberration corrected STEM of iron rhodium nanoislands

    Science.gov (United States)

    McLaren, M. J.; Hage, F. S.; Loving, M.; Ramasse, Q. M.; Lewis, L. H.; Marrows, C. H.; Brydson, R. M. D.

    2014-06-01

    Iron-rhodium (FeRh) nanoislands of equiatomic composition have been analysed using scanning transmission electron microscopy (STEM) electron energy loss spec-troscopy(EELS) and high angle annular dark field (HAADF) techniques. Previous magne-tometry results have lead to a hypothesis that at room temperature the core of the islands are antiferromagnetic while the shell has a small ferromagnetic signal. The causes of this effect are most likely to be a difference in composition at the edges or a strain on the island that stretches the lattice and forces the ferromagnetic transition. The results find, at the film-substrate interface, an iron-rich layer ~ 5 Å thick that could play a key role in affecting the magnetostructural transition around the interfacial region and account for the room temperature ferromagnetism.

  13. General Route to Cyclobutadiene Rhodium Complexes.

    Science.gov (United States)

    Perekalin, Dmitry S; Shvydkiy, Nikita V; Nelyubina, Yulia V; Kudinov, Alexander R

    2015-11-01

    Cyclobutadiene rhodium complexes bear high potential for applications in organometallic synthesis and catalysis. We have found that the cyclobutadiene complexes with substitutionally labile p-xylene ligands [(C4 R4 )Rh(p-xylene)](+) can be synthesized in one step from the commercially available bis(ethylene) complex [{(C2 H4 )2 RhCl}2 ], p-xylene, and internal alkynes. The replacement of p-xylene by various ligands provides a general access to other [(C4 R4 )Rh] compounds, such as [(C4 R4 )RhCl]x , [(C4 R4 )RhL3 ](+) , [(C4 R4 )Rh(C5 H5 )], and [(C4 R4 )Rh(arene)](+) . Complex [(C4 Et4 )Rh(p-xylene)](+) also catalyzes an unusual cycloisomerization of a 1,11-dien-6-yne into a bicyclic diene. PMID:26387565

  14. Tomography of actinides by photofission in bulky radioactive waste packages

    International Nuclear Information System (INIS)

    Quantifying actinides using non-destructive methods, in radioactive waste packages, is a great stake to turn packages towards appropriate storage facility. But the nature of radiations emitted by actinides (alpha radiations) makes the detection of those very difficult for large volume packages characterization. Indeed, the emitted radiation is too weak, either to be detected by emission tomography or to reach required sensitivities. Therefore, it is necessary to turn to an external probing source. Tomography based on detection of delayed neutrons induced by photofission, allows to probe bulky packages. We demonstrate the suitability of this method to an industrial stage. Firstly, we determine and qualify projection matrix which connects measures at reconstructed activity of tomographic picture. Thus, during measurements on a model and a real package, we carry out convincing tomographic reconstructions with real acquisition conditions. More, we prove that it is possible to take all disruptive chemical element into account, for tomographic reconstructions, in order to obtain the best image of activity. So, we propose a finalised tomographic device, integrating a shielding cell, and checking all the activity and distribution activity criterions fixed for acceptance of radioactive waste packages in superficial storage facility. (author)

  15. Surgical Management of Bulky Mediastinal Metastases in Follicular Thyroid Carcinoma

    Directory of Open Access Journals (Sweden)

    Zainal Adwin

    2016-01-01

    Full Text Available Follicular thyroid adenoma and carcinoma are very common. Benign and malignant lesions are usually indistinguishable from cytology alone and often require confirmatory resection. The spread of follicular carcinoma is usually hematogenous and is treated with surgery and adjuvant radioactive iodine. Very rarely, metastases occur in the mediastinum. Patients usually present with severe compressive symptoms. With proper treatment and follow-up, the prognosis for these type of thyroid malignancies is excellent. In the case presented here, our patient presented to the Universiti Kebangsaan Malaysia Medical Center with a progressively enlarging anterior neck swelling. The swelling had started 10 years before his presentation. We diagnosed him with an advanced thyroid malignancy with bulky mediastinal metastases. After extensive investigations and counseling, we chose to treat the patient with tumor excision and mediastinal metastases resection. Typically, mediastinal resection involves the removal of the sternum and use of an acrylic implant to recreate the sternum. In this case, the sternum and ribs were removed with subsequent myocutaneous flap coverage for the wound defect. Our experience represents an alternative treatment option in cases where implant use is unsuitable.

  16. The extraction of trichlorostannato-rhodium complexes by polyurethane foam

    International Nuclear Information System (INIS)

    Polyurethane foam (polyether based) has been found to efficiently extract rhodium from hydrochloric acid solutions containing stannous chloride. The amount of rhodium extracted is significantly influenced by inter alia temperature, acid concentration, the Sn(II):Rh mol ratio and the presence of alkali metal cations. The extraction efficiency is promoted by increased acid concentration and high Sn(II):Rh ratios. The presence of K+ inhibits the extraction or rhodium, while the effect of Li+ and Na+ is small. A series of model urethane compounds (diurethane podands and linear polyurethanes) have been synthesized and characterized. These model compounds allowed the direct determination of the extracted trichlorostannato-rhodium complex anions by 119Sn nmr spectroscopy. The 119Sn nmr study showed the formation of a new rhodium-hydrido complex formulated to be [RhH(SnCl3)4Cl]3-. In the presence of low tin(II) concentrations (Sn(II):Rh = 4:1), [Rh(SnCl3)3Cl3]3- is predominantly extracted by the foam phase. Analysis of the acid-decomposed polyurethane foam phase by atomic absorption spectroscopy and of the model urethane compound phase by 7Li nmr spectroscopy, confirmed the extraction of alkali metal cations from aqueous solutions containing alkali metal salts. It is indicated that the polyether chains of polyurethane foam play a major role in the extraction process, and that the flexibility of the chains influences the efficiency of polyurethane foam as an extractant. The creation of cationic sites within the foam matrix, which facilitate the extraction of the rhodium-tin complex anions, is postulated to occur by protonation of the donor oxygen atoms as well as by chelation of cations such as H3O+, Li+, Na+ and K+ by the polyether chains. A working model for the extraction of the trichlorostannato-rhodium complexes by polyurethane foam is proposed. 79 figs., 51 tabs., 272 refs

  17. Dependence of frame catalysts composition of the rhodium-ruthenium system on conditions of aluminium leacing

    International Nuclear Information System (INIS)

    The alteration in the composition of frame rhodium-ruthenium catalytic electrodes is studied depending on temperature (0-40O deg C) and time (24h) of their leaching. It is shown that the greater part of residual aluminium in catalysts of rhodium-ruthenium system is in the form of bayerite. The chemical composition of frame rhodium-ruthenium catalysts is established

  18. Reduction of nitric oxide over platinum, rhodium and platinum-rhodium single crystal surfaces. Doctoral thesis

    Energy Technology Data Exchange (ETDEWEB)

    Siera, J.

    1992-11-11

    Although platinum and rhodium are introduced separately in the three-way catalyst, it is established that Pt-Rh alloy particles are formed during its performance. Despite the widespread use of the three-way catalyst and the intensive research on the catalytic properties of the pure metals, relatively little is known about the alloy system. In the thesis results are described for the NO-H2, NO-NH3, CO-O2 and CO-NO reactions on the surfaces of Pt, Rh and Pt-Rh alloy single crystals.

  19. Underlying structure of bulky oxide nodule on alumina-forming austenitic stainless steel

    International Nuclear Information System (INIS)

    The bulky oxide nodule and its underlying structure were investigated in an alumina-forming austenitic steel exposed to dry air at 1053 K for 336 h. Some bulky oxide nodules were found to be attached on globular phases in the matrix. By combined application of electron backscattering diffraction and energy dispersive X-ray spectroscopy, the bulky nodule was identified as Cr-rich M3O4 underlying which was Nb-rich MO2. Thermodynamic calculation suggested that the MO2 was transformed from the primary NbC near surface

  20. Intercalation Compounds of Barium and Strontium Phenylphosphonate

    Czech Academy of Sciences Publication Activity Database

    Beneš, L.; Melánová, Klára; Svoboda, Jan; Zima, Vítězslav; Růžička, A.

    Pardubice : Institute of Macromolecular Chemistry AS CR, 2011. s. 172. ISBN 978-80-85009-66-8. [16th International Symposium on Intercalation Compounds. 23.05.2011-26.05.2011, Seč] Institutional research plan: CEZ:AV0Z40500505 Keywords : intercalates * layered compounds * structure Subject RIV: CA - Inorganic Chemistry

  1. Intercalated compounds of niobium and tantalum dicalcogenides

    International Nuclear Information System (INIS)

    The synthesis of niobium and tantalum lamellar compounds and its intercalated derivatives is described. The intercalated compounds with lithium, with alkaline metal and with metals of the first-row transition are studied, characterized by X-ray diffraction. (C.G.C.)

  2. Intercalation of lactones into vanadyl phosphate

    Science.gov (United States)

    Melánová, Klára; Beneš, Ludvík; Svoboda, Jan; Zima, Vítězslav

    2006-05-01

    Intercalates of vanadyl phosphate with α-methyl-γ-butyrolactone, γ-valerolactone, γ-caprolactone, δ-valerolactone, and ɛ-caprolactone were prepared by a displacement reaction of ethanol-intercalated VOPO4. As follows from the results of elemental analyses and thermogravimetry, intercalates contain about one molecule of the guest per formula unit. The diffractograms of the intercalates show a series of sharp (001) reflections, (200) reflection and some (hkl) lines with low intensity. The tetragonal lattice parameters of the intercalates were calculated. Both δ-valerolactone and ɛ-caprolactone intercalates are stable in air. The intercalates of lactones with side aliphatic chains are less stable. The CO stretching vibration in IR spectra of the intercalates prepared was shifted to lower wavenumbers in comparison with spectra of the pure guests, indicating that lactones are anchored to the host layers by their carbonyl oxygen. Analogously to the arrangement of γ-butyrolactone, also arrangement of molecules of other lactones in the interlayer space of the host layers was proposed.

  3. Intercalation chemistry of zirconium 4-sulfophenylphosphonate

    Energy Technology Data Exchange (ETDEWEB)

    Svoboda, Jan [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovský Sq. 2, 162 06 Prague 6 (Czech Republic); Zima, Vítězslav, E-mail: vitezslav.zima@upce.cz [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovský Sq. 2, 162 06 Prague 6 (Czech Republic); Melánová, Klára [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovský Sq. 2, 162 06 Prague 6 (Czech Republic); Beneš, Ludvík [Faculty of Chemical Technology, University of Pardubice, 532 10 Pardubice (Czech Republic); Trchová, Miroslava [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovský Sq. 2, 162 06 Prague 6 (Czech Republic)

    2013-12-15

    Zirconium 4-sulfophenylphosphonate is a layered material which can be employed as a host for the intercalation reactions with basic molecules. A wide range of organic compounds were chosen to represent intercalation ability of zirconium 4-sulfophenylphosphonate. These were a series of alkylamines from methylamine to dodecylamine, 1,4-phenylenediamine, p-toluidine, 1,8-diaminonaphthalene, 1-aminopyrene, imidazole, pyridine, 4,4′-bipyridine, poly(ethylene imine), and a series of amino acids from glycine to 6-aminocaproic acid. The prepared compounds were characterized by powder X-ray diffraction, thermogravimetry analysis and IR spectroscopy and probable arrangement of the guest molecules in the interlayer space of the host is proposed based on the interlayer distance of the prepared intercalates and amount of the intercalated guest molecules. - Graphical abstract: Nitrogen-containing organic compounds can be intercalated into the interlayer space of zirconium 4-sulfophenylphosphonate. - Highlights: • Zirconium 4-sulfophenylphosphonate was examined as a host material in intercalation chemistry. • A wide range of nitrogen-containing organic compounds were intercalated. • Possible arrangement of the intercalated species is described.

  4. About the extraction recovery of fission rhodium from radioactive wastes

    International Nuclear Information System (INIS)

    The report will cover a radically new approach to the problem of rhodium recovery from HLLW after the transformation of kinetically inert poly-aqua cation of trivalent rhodium (which is not recoverable by the majority known extractants) to Rh (IV) form by chemical methods. Presented are the research results of Rh (IV) extraction from nitric acid solutions by several extractants that are of considerable current use in noble metals and radiochemical industries (tri-n-butyl phosphate, di-octyl-sulphide, tri-n-octylamine, quaternary ammonium bases). High level of rhodium extraction has been found for the above extractants: for several systems, for example, tri-n-octylamine - diethyl-benzene, rhodium distribution coefficient achieves high values (10-plus), as well as the sufficient extraction kinetics. Rhodium extraction increases with a decrease of the acidity, a rise in phase mixing time and in the following series: tri-n-butyl phosphate → di-octyl-sulphide → quaternary ammonium bases → tri-n-octylamine. Rh (IV) can be easily reduced to non-extractable Rh (III) by such reductants as Fe (II), HCOOH, C6H8O6, NH2OH, N2H4 et al, that may be applied for the re-extraction process. (authors)

  5. Triplex glue by synthesizing conjugated flexible intercalators.

    Science.gov (United States)

    Pedersen, Erik B; Osman, Amany M A; Globisch, Daniel; Paramasivam, Manikandan; Cogoi, Susanna; Bomholt, Niels; Jørgensen, Per T; Xodo, Luigi E; Filichev, Vyacheslav V

    2008-01-01

    Bulge insertions of conjugated intercalators into the DNA triplex structure are found to give a dramatic contribution to the triplex stability. On the other hand insertions of conjugated intercalators are found to diminish quadruplex structures and in this way breaking down the self association of G-rich oligonucleotides under physiologically potassium ion conditions. A large number of intercalators are described here and they all result in dramatic increases of thermal stability of the corresponding triplexes. Another interesting aspect of conjugated intercalators is their use for assembling alternate strand triplexes. Targeting of neighbouring purine sequences on each their strand in the duplex DNA is a challenge for the 5'- 5' connectivity of the TFOs because of a large distance between the 5'-ends. The intercalator approach offers a linkage with the proper combination of flexibility and rigidity to produce alternate strand triplexes with higher stability than a similar wild type triplex of the same total length. PMID:18776241

  6. Intercalation of lanthanide trichlorides in graphite

    International Nuclear Information System (INIS)

    The reactions of the whole series of lanthanide trichlorides with graphite have been investigated. Intercalation compounds have been prepared with the chlorides of Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc, Y whereas LaCl3, CeCl3, PrCl3 and NdCl3 do not intercalate. The compounds were characterized by chemical and X-ray analysis. The amount of c-axis increase is consistent with the assumption that the chlorides are intercalated in form of a chloride layer sandwich resmbling the sheets in YCl3. The chlorides which do not intercalate crystallize in the UCl3 structure having 3 D arrangements of ions. Obviously, these chlorides cannot form sheets between the carbon layers. The ability of AlCl3 to volatilize lanthanide chlorides through complex formation in the gas phase can be used to increase the intercalation rate strikingly. (author)

  7. Modern induction chemotherapy before chemoradiation for bulky locally-advanced nonsmall cell lung cancer improves survival

    Directory of Open Access Journals (Sweden)

    Inaya Ahmed

    2016-01-01

    Conclusion: In patients with large tumors or bulky nodal NSCLC, carboplatin-based induction chemotherapy may be an important addition to definitive CCRT in the modern era. Our findings strongly support further investigation induction chemotherapy in this population.

  8. Influence of support nature on ruthenuim-rhodium catalyst properties

    International Nuclear Information System (INIS)

    Influence of support nature (ThO2, TiO2, γ-Al2O3, activated carbon) on 1% ruthenium-rhodium catalysts properties is studied in the reaction of liquid-phase hydrogenation of model compou with different type of unsaturated bonds at room temperature and atmosphere pressure. It is shown that dependences of hydrogenation rate on the ratio of applied ruthenium and rhodium are extremal. The maximum position is determined by support nature and is practically constant at hydrogenation of different substances. Influence of support nature on the given composition catalyst activity is slightly dpendent on chemical nature of hydrogenated compound and is opposite for ruthenium and rhodium catalysts

  9. Size control of rhodium particles of silica-supported catalysts using water-in-oil microemulsion

    Science.gov (United States)

    Kishida, Masahiro; Hanaoka, Toshiaki; Kim, Won Young; Nagata, Hideo; Wakabayashi, Katsuhiko

    1997-11-01

    Effects of components of water-in-oil microemulsions on rhodium particle sizes of silica-supported rhodium catalysts were investigated in the catalyst preparation method using microemulsion. In the case of the microemulsion of polyoxyethylene(23)dodecyl ether/ n-alcohols/RhCl 3 aq., the rhodium particle size increased from 3.4 to 5.0 nm as the specific permittivity of the organic solvent increased. The chain length of hydrophilic group of polyoxyethylene- p-nonylphenyl ether ( n = 5 to 15) employed as surfactants had an effect on the rhodium particle size where the rhodium size ranged between 2.0 and 3.6 nm. The rhodium particle size was 1.5 nm in the case of sodium bis(2-ethylhexyl) sulfocuccinate and this value was found to be the smallest. These results could be interpreted in terms of the adsorption of the surfactant on rhodium-hydrazine particle surface.

  10. Snapshot analysis for rhodium fixed incore detector using BEACON methodology

    International Nuclear Information System (INIS)

    The purpose of this report is to process the rhodium detector data of the Yonggwang nuclear unit 4 cycle 5 core for the measured power distribution by using the BEACON methodology. Rhodium snapshots of the YGN 4 cycle 5 have been analyzed by both BEACON/SPINOVA and CECOR to compare the results of both codes. By analyzing a large number of snapshots obtained during normal plant operation. Reviewing the results of this analysis, the BEACON/SPNOVA can be used for the snapshot analysis of Korean Standard Nuclear Power (KSNP) plants

  11. The intercalated cells of the amygdala.

    Science.gov (United States)

    Millhouse, O E

    1986-05-01

    The intercalated cell groups, or massa intercalata, of the amygdala have been studied in rodent brains with Golgi methods. They also have been examined in gallocyanin-chromalum-, AChE-, and Timm-stained rat brains. The Golgi data indicate that the intercalated cells are not confined to a series of isolated cell clumps but form a neuronal net that covers the rostral half of the lateral-basolateral nuclear complex, stretches across a major portion of rostral amygdala, and continues rostrally beneath the anterior commissure. There are two general types of intercalated neuron--medium and large neurons. The medium intercalated neurons are more common. They have round to elongate somata, 9-18 microns in diameter, and round to bipolar dendritic trees, depending on their location. Most of the dendrites are spine-bearing, as are 20% of the somata. Their axons often have locally ramifying collaterals. The parent axons apparently terminate in either the lateral-basolateral or central nuclei and some of them appear to enter the external capsule. There is a unique medium intercalated neuron that has nearly spine-free, varicose dendrites and an axon that is typical of short axon (Golgi II) cells. There are two varieties of large intercalated neuron-spiny and aspiny. Most of them are aspiny, although they usually have a few spines scattered along their dendrites. Both varieties have elongate, sometimes round, somata that can be as much as 60 microns long. Their dendrites are long, thick, and have few branch points. Only the initial part of the large aspiny cell axon has been impregnated. The large spiny cell axons have several local collaterals; the destination of the parent axons is unknown. The intercalated cells occur along fiber bundles, which are probably afferent to them. The axons that travel among the intercalated cells give off short collaterals and boutons en passant. The sources of these fibers are not known. From the published experimental data, it is likely that they

  12. Effect of water intercalation on VOx layers in dodecylamine-intercalated vanadium oxide nanotubes

    Science.gov (United States)

    Kweon, Hyocheon; Lee, Kyu Won; Lee, Eun Mo; Park, Jitae; Kim, I.-M.; Lee, Cheol Eui; Jung, G.; Gedanken, A.; Koltypin, Yu.

    2007-07-01

    Dodecylamine-intercalated vanadium oxide nanotubes were obtained by distinct synthesis processes. Water intercalation in the nanotube structure was identified in a marked manner by the distortion of the VOx layers in the x-ray diffraction patterns and enhanced V4+O absorption in the Fourier-transform infrared spectra. Our electron spin resonance measurements sensitively reflect changes in the microscopic structure and magnetic interactions introduced by the water intercalation in the vanadium oxide nanotubes.

  13. SURFACE STRUCTURE AND COMPOSITION CHANGES ON PLATINUM - RHODIUM ALLOY CATALYSTS

    OpenAIRE

    McCabe, A.; Smith, G.

    1984-01-01

    Platinum-rhodium gauze catalysts used in the manufacture of nitric acid undergo an extensive surface reconstruction process. This has been investigated using a miniature catalytic reactor, FIM atom probe, electron microscopy and X-ray techniques. A mechanism involving vapour transport is proposed to explain the main features of the variation in catalyst behaviour with operating conditions.

  14. Electronic and magnetic properties of small rhodium clusters

    Energy Technology Data Exchange (ETDEWEB)

    Soon, Yee Yeen; Yoon, Tiem Leong [School of Physics, Universiti Sains Malaysia, 11800 USM, Penang (Malaysia); Lim, Thong Leng [Faculty of Engineering and Technology, Multimedia University, Melaka Campus, 75450 Melaka (Malaysia)

    2015-04-24

    We report a theoretical study of the electronic and magnetic properties of rhodium-atomic clusters. The lowest energy structures at the semi-empirical level of rhodium clusters are first obtained from a novel global-minimum search algorithm, known as PTMBHGA, where Gupta potential is used to describe the atomic interaction among the rhodium atoms. The structures are then re-optimized at the density functional theory (DFT) level with exchange-correlation energy approximated by Perdew-Burke-Ernzerhof generalized gradient approximation. For the purpose of calculating the magnetic moment of a given cluster, we calculate the optimized structure as a function of the spin multiplicity within the DFT framework. The resultant magnetic moments with the lowest energies so obtained allow us to work out the magnetic moment as a function of cluster size. Rhodium atomic clusters are found to display a unique variation in the magnetic moment as the cluster size varies. However, Rh{sub 4} and Rh{sub 6} are found to be nonmagnetic. Electronic structures of the magnetic ground-state structures are also investigated within the DFT framework. The results are compared against those based on different theoretical approaches available in the literature.

  15. Discovery of Rubidium, Strontium, Molybdenum, and Rhodium Isotopes

    OpenAIRE

    Parker, A. M.; Thoennessen, M

    2011-01-01

    Currently, thirty-one rubidium, thirty-five strontium, thirty-five molybdenum and thirty-eight rhodium isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

  16. 1-Hexyne Cyclotrimerization Catalyzed by Cyclopentadienyl Rhodium(I) Complexes

    Czech Academy of Sciences Publication Activity Database

    Auerová, Kateřina; Čermák, Jan; Blechta, Vratislav; Kvíčala, J.

    Tarragona: Ind. Gráf. Gabriel Gibert, 2002. s. 310. [International Symposium on Homogeneous Catalysis /13./. 03.09.2002-07.09.2002, Tarragona] R&D Projects: GA AV ČR IAA4072203 Keywords : trimerization * rhodium catalysts * cyclopentadienyl complexes Subject RIV: CC - Organic Chemistry

  17. Support Effect in the Hydrodesulfurization of Thiophene over Rhodium Sulfide

    Czech Academy of Sciences Publication Activity Database

    Kaluža, Luděk; Vít, Zdeněk; Zdražil, Miroslav

    2010-01-01

    Roč. 101, č. 1 (2010), s. 63-72. ISSN 1878-5190 R&D Projects: GA ČR GA104/09/0751 Institutional research plan: CEZ:AV0Z40720504 Keywords : hydrodesulfurization * thiophene * rhodium sulfide Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  18. Diphosphinoazine Complexes of Rhodium-synthesis, Structure and Reactivity

    Czech Academy of Sciences Publication Activity Database

    Pošta, Martin; Čermák, Jan; Vojtíšek, P.

    Prague: J. Heyrovsky Institute of Physical Chemistry, 2004, s. 76-77. [Symposium on Catalysis /36./. Praha (CZ), 08.11.2004-09.11.2004] R&D Projects: GA ČR GA203/01/0554 Institutional research plan: CEZ:AV0Z4072921 Keywords : diphosphinoazines * rhodium Subject RIV: CC - Organic Chemistry

  19. Synthesis of Rhodium Diphosphinoazine Complexes as Potential Catalysts

    Czech Academy of Sciences Publication Activity Database

    Pošta, Martin; Čermák, Jan; Vojtíšek, V.; Carvalho, M. F. N. N.

    Prague, 2003. s. 44. [Symposium on Catalysis /35./. 03.11.2003-04.11.2003, Prague] R&D Projects: GA ČR GA203/01/0554 Institutional research plan: CEZ:AV0Z4072921 Keywords : catalysts * Rhodium Subject RIV: CC - Organic Chemistry

  20. Rhodium-catalyzed C-C bond cleavage reactions

    Czech Academy of Sciences Publication Activity Database

    Nečas, D.; Kotora, Martin

    2007-01-01

    Roč. 11, č. 17 (2007), s. 1566-1591. ISSN 1385-2728 Institutional research plan: CEZ:AV0Z40550506 Keywords : rhodium * catalysis * C-C bond cleavage Subject RIV: CC - Organic Chemistry Impact factor: 3.961, year: 2007

  1. Electronic and magnetic properties of small rhodium clusters

    International Nuclear Information System (INIS)

    We report a theoretical study of the electronic and magnetic properties of rhodium-atomic clusters. The lowest energy structures at the semi-empirical level of rhodium clusters are first obtained from a novel global-minimum search algorithm, known as PTMBHGA, where Gupta potential is used to describe the atomic interaction among the rhodium atoms. The structures are then re-optimized at the density functional theory (DFT) level with exchange-correlation energy approximated by Perdew-Burke-Ernzerhof generalized gradient approximation. For the purpose of calculating the magnetic moment of a given cluster, we calculate the optimized structure as a function of the spin multiplicity within the DFT framework. The resultant magnetic moments with the lowest energies so obtained allow us to work out the magnetic moment as a function of cluster size. Rhodium atomic clusters are found to display a unique variation in the magnetic moment as the cluster size varies. However, Rh4 and Rh6 are found to be nonmagnetic. Electronic structures of the magnetic ground-state structures are also investigated within the DFT framework. The results are compared against those based on different theoretical approaches available in the literature

  2. Resistance to Nucleotide Excision Repair of Bulky Guanine Adducts Opposite Abasic Sites in DNA Duplexes and Relationships between Structure and Function.

    Directory of Open Access Journals (Sweden)

    Zhi Liu

    Full Text Available The nucleotide excision repair of certain bulky DNA lesions is abrogated in some specific non-canonical DNA base sequence contexts, while the removal of the same lesions by the nucleotide excision repair mechanism is efficient in duplexes in which all base pairs are complementary. Here we show that the nucleotide excision repair activity in human cell extracts is moderate-to-high in the case of two stereoisomeric DNA lesions derived from the pro-carcinogen benzo[a]pyrene (cis- and trans-B[a]P-N2-dG adducts in a normal DNA duplex. By contrast, the nucleotide excision repair activity is completely abrogated when the canonical cytosine base opposite the B[a]P-dG adducts is replaced by an abasic site in duplex DNA. However, base excision repair of the abasic site persists. In order to understand the structural origins of these striking phenomena, we used NMR and molecular spectroscopy techniques to evaluate the conformational features of 11mer DNA duplexes containing these B[a]P-dG lesions opposite abasic sites. Our results show that in these duplexes containing the clustered lesions, both B[a]P-dG adducts adopt base-displaced intercalated conformations, with the B[a]P aromatic rings intercalated into the DNA helix. To explain the persistence of base excision repair in the face of the opposed bulky B[a]P ring system, molecular modeling results suggest how the APE1 base excision repair endonuclease, that excises abasic lesions, can bind productively even with the trans-B[a]P-dG positioned opposite the abasic site. We hypothesize that the nucleotide excision repair resistance is fostered by local B[a]P residue-DNA base stacking interactions at the abasic sites, that are facilitated by the absence of the cytosine partner base in the complementary strand. More broadly, this study sets the stage for elucidating the interplay between base excision and nucleotide excision repair in processing different types of clustered DNA lesions that are substrates of

  3. Hydrogen intercalation under graphene on Ir(111)

    Science.gov (United States)

    Grånäs, Elin; Gerber, Timm; Schröder, Ulrike A.; Schulte, Karina; Andersen, Jesper N.; Michely, Thomas; Knudsen, Jan

    2016-09-01

    Using high resolution X-ray photoelectron spectroscopy and scanning tunneling microscopy we study the intercalation of hydrogen under graphene/Ir(111). The hydrogen intercalated graphene is characterized by a component in C 1s that is shifted -0.10 to -0.18 eV with respect to pristine graphene and a component in Ir 4f at 60.54 eV. The position of this Ir 4f component is identical to that of the Ir(111) surface layer with hydrogen atoms adsorbed, indicating that the atomic hydrogen adsorption site on bare Ir(111) and beneath graphene is the same. Based on co-existence of fully- and non-intercalated graphene, and the inability to intercalate a closed graphene film covering the entire Ir(111) surface, we conclude that hydrogen dissociatively adsorbs at bare Ir(111) patches, and subsequently diffuses rapidly under graphene. A likely entry point for the intercalating hydrogen atoms is identified to be where graphene crosses an underlying Ir(111) step.

  4. Rhodium catalysed hydroformylation of alkenes using highly fluorophilic phosphines.

    Science.gov (United States)

    Adams, Dave J; Bennett, James A; Cole-Hamilton, David J; Hope, Eric G; Hopewell, Jonathan; Kight, Jo; Pogorzelec, Peter; Stuart, Alison M

    2005-12-21

    Highly fluorophilic phosphines incorporating at least one aromatic ring containing two directly attached perfluoroalkyl groups have been synthesised, their partition coefficients (organic phase : fluorous phase) measured and their electronic properties probed using (1)J(PtP) data for their trans-[PtCl(2)L(2)] complexes. These phosphines have been used as modifying ligands for the rhodium catalysed hydroformylation of 1-octene in perfluorocarbon solvents. Catalyst activity, regioselectivity and the levels of rhodium leaching to the product phase vary with the substitution patterns of the modifying ligands that do not correlate with the electronic properties or partition coefficients of these ligands, but can be interpreted in terms of differences in the resting states of the catalysts. PMID:16311639

  5. Plasmonics in the UV range with Rhodium nanocubes

    Science.gov (United States)

    Zhang, X.; Gutiérrez, Y.; Li, P.; Barreda, Á. I.; Watson, A. M.; Alcaraz de la Osa, R.; Finkelstein, G.; González, F.; Ortiz, D.; Saiz, J. M.; Sanz, J. M.; Everitt, H. O.; Liu, J.; Moreno, F.

    2016-04-01

    Plasmonics in the UV-range constitutes a new challenge due to the increasing demand to detect, identify and destroy biological toxins, enhance biological imaging, and characterize semiconductor devices at the nanometer scale. Silver and aluminum have an efficient plasmonic performance in the near UV region, but oxidation reduces its performance in this range. Recent studies point out rhodium as one of the most promising metals for this purpose: it has a good plasmonic response in the UV and, as gold in the visible, it presents a low tendency to oxidation. Moreover, its easy fabrication through chemical means and its potential for photocatalytic applications, makes this material very attractive for building plasmonic tools in the UV. In this work, we will show an overview of our recent collaborative research with rhodium nanocubes (NC) for Plasmonics in the UV.

  6. Environmental, Dietary, Maternal, and Fetal Predictors of Bulky DNA Adducts in Cord Blood

    DEFF Research Database (Denmark)

    Pedersen, Marie; Mendez, Michelle A; Schoket, Bernadette;

    2015-01-01

    BACKGROUND: Bulky DNA adducts reflect genotoxic exposures, have been associated with lower birth weight, and may predict cancer risk. OBJECTIVE: We selected factors known or hypothesized to affect in utero adduct formation and repair and examined their associations with adduct levels in neonates....

  7. Monitoring lipase-catalyzed interesterification for bulky fats modification with FT-IR/NIR spectroscopy

    DEFF Research Database (Denmark)

    Chang, Tinghong; Lai, Xuxin; Zhang, Hong;

    2005-01-01

    This work demonstrates the application of FT-IR and FT-NIR spectroscopy to monitor the enzymatic interesterification process for bulky fat modification. The reaction was conducted between palm stearin and coconut oil (70/30, w/w) with the catalysis of Lipozyme TL IM at 70°C in a batch reactor...

  8. Turning the Page: Forget about Those Bulky Backbreakers, Digital Textbooks Are the Future

    Science.gov (United States)

    Hill, Rebecca

    2010-01-01

    Remember when computers were mostly used in offices? They were big and bulky with about as much mobility as a beached whale. Forget about using them in the classroom. Forget about reading a book on them. Forget about an app, well, for anything. Today, computers are the number-one educational tool. In fact, no one can imagine a school without one.…

  9. Surface science studies of Cobalt and Rhodium single crystal surfaces

    OpenAIRE

    Ramsvik, Trond

    2001-01-01

    The main topic of this thesis is the investigation of small molecules adsorbed on the transition metals cobalt and rhodium surfaces by means of predominantly high-resolution core level photoemission and near edge x-ray absorption fine structure (NEXAFS). The thesis can be divided into three parts where the following phenomena are examined:1) internal molecular vibrations in the core level photoemission spectra2) hybridisation and thermal decomposition of adsorbates3) growth and surface alloy ...

  10. Methane Steam Reforming Kinetics for a Rhodium-Based Catalyst

    DEFF Research Database (Denmark)

    Jakobsen, Jon Geest; Jakobsen, M.; Chorkendorff, Ib;

    2010-01-01

    Methane steam reforming is the key reaction to produce synthesis gas and hydrogen at the industrial scale. Here the kinetics of methane steam reforming over a rhodium-based catalyst is investigated in the temperature range 500-800 A degrees C and as a function of CH4, H2O and H-2 partial pressure...... that lowers the adsorption energy at high CO coverage. The CO-CO interaction is supported by comparison with fundamental surface science studies....

  11. Bioenvironmental aspects of europium and rhodium: a selected bibliography

    International Nuclear Information System (INIS)

    This bibliography of 428 abstracted references represents a summary of the domestic and foreign literature relevant to the biological and environmental aspects of europium and rhodium. The collected data are organized by current NAEG interests - research highlighting inventory and distribution of the radionulcides, ecological studies covering terrestrial and aquatic systems, and biological studies in both man and animals. Studies that focus directly on research conducted at specific sites (e.g., the Nevada Test Site) are emphasized throughout the bibliography

  12. Support Effect in Hydrodesulfurization of Thiophene over Rhodium Sulfide

    Czech Academy of Sciences Publication Activity Database

    Kaluža, Luděk; Vít, Zdeněk; Zdražil, Miroslav

    Prague: J. Heyrovský Institute of Physical Chemistry of the ASCR, v.v.i, 2009, s. 74-75. ISBN 978-80-87351-04-8. [Symposium on Catalysis /41./. Prague (CZ), 02.11.2009-03.11.2009] R&D Projects: GA ČR GA104/09/0751 Institutional research plan: CEZ:AV0Z40720504 Keywords : hydrodesulfurization * rhodium sulfide * support effect Subject RIV: CF - Physical ; Theoretical Chemistry

  13. Rhodium catalysts for isotopic exchange between hydrogen and water vapor

    International Nuclear Information System (INIS)

    Catalysts were prepared by depositing rhodium on porous polystyrene copolymer. The activity of the catalysts for the isotopic exchange reaction in the hydrogen-water vapor system was determined by the nearness of approach to isotopic equilibrium between the two reactants after passing through the column. A known quantity of catalyst was packed in a 1 cm diameter glass column to depth varying 2 to 5 cm. The degree of approach to isotopic equilibrium was as high as 60 to 100 %

  14. Rhodium(II)-catalyzed enantioselective synthesis of troponoids.

    Science.gov (United States)

    Murarka, Sandip; Jia, Zhi-Jun; Merten, Christian; Daniliuc, Constantin-G; Antonchick, Andrey P; Waldmann, Herbert

    2015-06-22

    We report a rhodium(II)-catalyzed highly enantioselective 1,3-dipolar cycloaddition reaction between the carbonyl moiety of tropone and carbonyl ylides to afford troponoids in good to high yields with excellent enantioselectivity. We demonstrate that α-diazoketone-derived carbonyl ylides, in contrast to carbonyl ylides derived from diazodiketoesters, undergo [6+3] cycloaddition reactions with tropone to yield the corresponding bridged heterocycles with excellent stereoselectivity. PMID:25959033

  15. Scalar Relativistic Study of the Structure of Rhodium Acetate

    Directory of Open Access Journals (Sweden)

    Emily E. Edwards

    2004-01-01

    Full Text Available Abstract: Rhodium acetate, related rhodium carboxylates, and rhodium amide complexes are powerful catalysts for carbene chemistry. They readily promote the decomposition of diazo compounds and transfer the resulting carbene to a variety of substrates. There have been several quantum chemistry studies of these compounds, particularly of the acetate. These have all used non-relativistic methods, and all have shown optimized Rh-Rh bond lengths significantly longer than the experimental value. In this study we have surveyed several scalar relativistic DFT methods using Gaussian, Slater, and numerical basis functions (in DGAUSS, ADF, and DMOL3. Several combinations of exchange-correlation functionals with relativistic and non-relativistic effective core potentials (ECP were investigated, as were non-relativistic and all electron scalar relativistic methods. The combination of the PW91 exchange and PW91 correlation functional with the Christiansen-Ermler ECP gave the best results: 2.3918 Å compared to the experimental value of 2.3855±0.0005 Å.

  16. Modelling informally collected quantities of bulky waste and reusable items in Austria

    International Nuclear Information System (INIS)

    Highlights: • Informal collectors from Hungary collect bulky waste and reusable items in Austria. • Two methodologies were applied to estimate the informally collected quantities. • Both approaches lead to an estimation of roughly 100,000 t p.a. informally collected. • The formal Austrian system collects 72 kg/cap/yr of bulky waste, WEE & scrap metal. • Informal collection amounts to approx. 12 kg/cap/yr. - Abstract: Disparities in earnings between Western and Eastern European countries are the reason for a well-established informal sector actively involved in collection and transboundary shipment activities from Austria to Hungary. The preferred objects are reusable items and wastes within the categories bulky waste, WEEE and metals, intended to be sold on flea markets. Despite leading to a loss of recyclable resources for Austrian waste management, these informal activities may contribute to the extension of the lifetime of certain goods when they are reused in Hungary; nevertheless they are discussed rather controversially. The aim of this paper is to provide objective data on the quantities informally collected and transhipped. The unique activities of informal collectors required the development and implementation of a new set of methodologies. The concept of triangulation was used to verify results obtained by field visits, interviews and a traffic counting campaign. Both approaches lead to an estimation of approx. 100,000 t per year of reusable items informally collected in Austria. This means that in addition to the approx. 72 kg/cap/yr formally collected bulky waste, bulky waste wood, household scrap (excluding packaging) and WEEE, up to a further 12 kg/cap/yr might, in the case that informal collection is abandoned, end up as waste or in the second-hand sector

  17. Modelling informally collected quantities of bulky waste and reusable items in Austria

    Energy Technology Data Exchange (ETDEWEB)

    Ramusch, R., E-mail: roland.ramusch@boku.ac.at; Pertl, A.; Scherhaufer, S.; Schmied, E.; Obersteiner, G.

    2015-10-15

    Highlights: • Informal collectors from Hungary collect bulky waste and reusable items in Austria. • Two methodologies were applied to estimate the informally collected quantities. • Both approaches lead to an estimation of roughly 100,000 t p.a. informally collected. • The formal Austrian system collects 72 kg/cap/yr of bulky waste, WEE & scrap metal. • Informal collection amounts to approx. 12 kg/cap/yr. - Abstract: Disparities in earnings between Western and Eastern European countries are the reason for a well-established informal sector actively involved in collection and transboundary shipment activities from Austria to Hungary. The preferred objects are reusable items and wastes within the categories bulky waste, WEEE and metals, intended to be sold on flea markets. Despite leading to a loss of recyclable resources for Austrian waste management, these informal activities may contribute to the extension of the lifetime of certain goods when they are reused in Hungary; nevertheless they are discussed rather controversially. The aim of this paper is to provide objective data on the quantities informally collected and transhipped. The unique activities of informal collectors required the development and implementation of a new set of methodologies. The concept of triangulation was used to verify results obtained by field visits, interviews and a traffic counting campaign. Both approaches lead to an estimation of approx. 100,000 t per year of reusable items informally collected in Austria. This means that in addition to the approx. 72 kg/cap/yr formally collected bulky waste, bulky waste wood, household scrap (excluding packaging) and WEEE, up to a further 12 kg/cap/yr might, in the case that informal collection is abandoned, end up as waste or in the second-hand sector.

  18. Superconducting Calcium-Intercalated Bilayer Graphene.

    Science.gov (United States)

    Ichinokura, Satoru; Sugawara, Katsuaki; Takayama, Akari; Takahashi, Takashi; Hasegawa, Shuji

    2016-02-23

    We report the direct evidence for superconductivity in Ca-intercalated bilayer graphene C6CaC6, which is regarded as the thinnest limit of Ca-intercalated graphite. We performed the electrical transport measurements with the in situ 4-point-probe method in ultrahigh vacuum under zero- or nonzero-magnetic field for pristine bilayer graphene, Li-intercalated bilayer graphene (C6LiC6) and C6CaC6 fabricated on SiC substrate. We observed that the zero-resistance state occurs in C6CaC6 with the onset temperature (Tc(onset)) of 4 K, while the Tc(onset) is gradually decreased upon applying the magnetic field. This directly proves the superconductivity origin of the zero resistance in C6CaC6. On the other hand, both pristine bilayer graphene and C6LiC6 exhibit nonsuperconducting behavior, suggesting the importance of intercalated atoms and its species to drive the superconductivity. PMID:26815333

  19. Intercalation chemistry of several new metal organophosphonates

    Czech Academy of Sciences Publication Activity Database

    Zima, Vítězslav; Svoboda, Jan; Melánová, Klára; Beneš, L.

    Beijing : Tsinghua University, Beijing, China, 2009. s. 22-22. ISBN N. [15th International Symposium on Intercalation Compounds. 11.05.2009-15.05.2009, Beijing] R&D Projects: GA ČR(CZ) 203/08/0208 Institutional research plan: CEZ:AV0Z40500505 Keywords : phosphonate Subject RIV: CA - Inorganic Chemistry

  20. Intercalation behavior of zirconium 4-sulfophenylphosphonates

    Czech Academy of Sciences Publication Activity Database

    Beneš, L.; Melánová, Klára; Svoboda, Jan; Zima, Vítězslav

    Strasbourg: European Materials Research Society, 2010. s. 22-23. [E- MRS 2010 Spring Meeting. 07.06.2010 - 11. 06. 2010, Strasbourg] R&D Projects: GA ČR GA203/08/0208 Institutional research plan: CEZ:AV0Z40500505 Keywords : intercalation * amines * layered materials Subject RIV: CD - Macromolecular Chemistry

  1. Rhodium-Catalyzed Linear Codimerization and Cycloaddition of Ketenes with Alkynes

    OpenAIRE

    Teruyuki Kondo; Masatsugu Niimi; Yuki Yoshida; Kenji Wada; Take-aki Mitsudo; Yu Kimura; Akio Toshimitsu

    2010-01-01

    A novel rhodium-catalyzed linear codimerization of alkyl phenyl ketenes with internal alkynes to dienones and a novel synthesis of furans by an unusual cycloaddition of diaryl ketenes with internal alkynes have been developed. These reactions proceed smoothly with the same rhodium catalyst, RhCl(PPh3)3, and are highly dependent on the structure and reactivity of the starting ketenes.

  2. A nine-atom rhodium-aluminum oxide cluster oxidizes five carbon monoxide molecules.

    Science.gov (United States)

    Li, Xiao-Na; Zhang, Hua-Min; Yuan, Zhen; He, Sheng-Gui

    2016-01-01

    Noble metals can promote the direct participation of lattice oxygen of very stable oxide materials such as aluminum oxide, to oxidize reactant molecules, while the fundamental mechanism of noble metal catalysis is elusive. Here we report that a single atom of rhodium, a powerful noble metal catalyst, can promote the transfer of five oxygen atoms to oxidize carbon monoxide from a nine-atom rhodium-aluminum oxide cluster. This is a sharp improvement in the field of cluster science where the transfer of at most two oxygen atoms from a doped cluster is more commonly observed. Rhodium functions not only as the preferred trapping site to anchor and oxidize carbon monoxide by the oxygen atoms in direct connection with rhodium but also the primarily oxidative centre to accumulate the large amounts of electrons and the polarity of rhodium is ultimately transformed from positive to negative. PMID:27094921

  3. SHORT-TIME ANALYSIS FOR ADJUVANT CHEMOTHERAPY IN PATIENTS WITH EARLY-STAGE BULKY CERVICAL CARCINOMA

    Institute of Scientific and Technical Information of China (English)

    令狐华; 徐小蓉; 梅耀宇; 唐均英; 唐良萏; 孙彤

    2003-01-01

    Objective: To investigate the effect of adjuvant chemotherapy on early stage cervical cancer with bulky tumor. Methods: Between Mar 1998 and Aug 2002, 162 patients of cervical cancer with Ib~IIa stage were investigated. 21 patients with bulky tumors (≥4cm) were managed by cisplatin-based chemotherapy followed by radical hysterectomy and pelvic lymphadenectomy (Bulky-chemo group, BC group). The change of tumor size, the depth of stromal invasion, lymph node metastasis and the involvement of surgical specimens were assessed after operation and compared with those in 57 patients with bulky tumors (Bulky-nonchemo group, BN group) and 84 patients with the tumor size less than 4cm (small group, S group) who underwent surgery as the first step of treatment. Chemotherapy with the same regimen was offered for another 1~2 cycles after operation and the survival situation was followed up. Results: The tumor size of 21 patients in BC group were decreased to varying degrees after chemotherapy, 15 patients were shown as clinical effectiveness (71.43%). And the blood loss during operation (352.35(19.01ml) was significantly lower than that in BN group (619.05(35.58ml), t=4.37) and that in S group (568.07(45.23ml, t=3.36) patients. The incidence of lymph node metastasis (9/78) in patients with bulky tumors was greatly higher than those with tumor size less than 4cm (3/84, X2=4.416); its prevalence rate of deep wall infiltration (8/78) was also higher than that of the latter group (2/84), while with no statistical significance (X2=3.089). Histology showed that there was no case of marginal involvement in all patients. The ratio of both deep stromal invasion (1/21) and positive lymph node (2/21) in BC group was lower than that in BN group (7/57, 7/57 respectively), but neither with statistical significance (X2=0.0103 and 0.8193 respectively). Conclusion: Pre-operative chemotherapy can improve decreasing the primary tumor size and facilitate the following radical surgery. While

  4. Atomic size-limited intercalation into single wall carbon nanotubes

    International Nuclear Information System (INIS)

    Intercalation of single wall carbon nanotubes (SWNTs) provides an important tool to modify their electronic band structure. Using multiple excitation wavelength Raman spectroscopy, we demonstrate that intercalation into SWNT interiors can be limited by intercalant size resulting in an unusual material comprising SWNTs with varying charge density. In the particular case of iodine intercalation, larger SWNTs with iodine-filled interiors were found to carry significantly higher charge density as compared to smaller empty ones. This difference was used to separate the intercalated SWNT material into fractions with homogeneous charge density

  5. AlkB recognition of a bulky DNA base adduct stabilized by chemical cross-linking

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    E.coli AlkB is a direct DNA/RNA repair protein that oxidatively reverses N1 alkylated purines and N3 alkylated pyrimidines to regular bases.Previous crystal structures have revealed N1-methyl adenine(1-meA) recognition by AlkB and a unique base flipping mechanism,but how the AlkB active site can accommodate bulky base adducts is largely unknown.Employing a previously developed chemical cross-linking technique,we crystallized AlkB with a duplex DNA containing a caged thymine base(cagedT).The structure revealed a flexible hairpin lid and a reorganized substrate recognition loop used by AlkB to accommodate cagedT.These observations demonstrate,at the molecular level,how bulky DNA adducts may be recognized and processed by AlkB.

  6. Stereotactic Radiosurgery as Part of Multimodal Treatment in a Bulky Leptomeningeal Recurrence of Breast Cancer.

    Science.gov (United States)

    Bertke, Matthew H; Burton, Eric C; Shaughnessy, Joseph N

    2016-01-01

    Breast cancer metastatic to the brain and/or leptomeningeal spread of disease is a frequently encountered clinical situation, especially given the extended course of disease in these patients. Systemic therapies can often effectively prolong extracranial disease control, making effective strategies to control central nervous system-based disease even more critical. We present a case of bulky leptomeningeal relapse of breast cancer in the setting of prior whole brain radiation therapy. In order to treat the patient's bulky disease and leptomeningeal spread while avoiding the potential toxicities of repeat whole brain radiation, the patient was treated with frameless stereotactic radiosurgery and intrathecal chemotherapy. This is the first report of this treatment approach for leptomeningeal relapse of breast cancer. The patient had an excellent response to treatment and durable intracranial control. PMID:27081584

  7. RESPONSE OF EARLY STAGE BULKY CERVICAL SQUAMOUS CARCINOMA TO PREOPERATIVE ADJUVANT CHEMOTHERAPY

    Institute of Scientific and Technical Information of China (English)

    Hua Linghu; Xiao-rong Xu; Yao-yu Mei; Jun-ying Tang; Liang-dan Tang; Tong Sun

    2004-01-01

    Objective To investigate the potential role of preoperative adjuvant chemotherapy on early stage cervical squamouscarcinoma with bulky tumor.Methods One hundred and forty-five patients with cervical squamous cancer stages Ⅰb-Ⅱa were investigated, among which 17 patients with bulky tumors (≥4 cm) were managed by cisplatin-based chemotherapy for 1-2 courses followed by radical hysterectomy and pelvic lymphadenectomy (BC group). The change of tumor size, pelvic lymph nodes metastasis, cervical wall invasion, the involvement of surgical specimen margin, and the blood loss during operation were assessed after operation and compared with those in 51 patients with bulky tumors (BN group) and 77 patients with small local tumors (S group)who underwent surgery directly.Results (1) The tumor size of 17 patients in BC group were decreased in various degrees after chemotherapy, with 13 patients of clinical effectiveness (76.47%). And the responsiveness pertained to neither histological differentiation nor size of local tumors. (2) Post-operative histology has showed that patients in BC and BN group have higher incidence of lymph node metastasis and deep cervical infiltration (5/68 and 3/68, respectively) than in S group (1/77 and 1/77, respectively) while with no statistical significance. (3) Blood loss during operation in BC group was less than BN and S group. (4) Seventeen patients, including those underwent surgeries of vaginal prolongation and/or ovarian transposition, appeared disease-free survival within the follow-up time.Conclusions Most of patients with bulky early stage cervical squamous carcinoma are sensitive to cisplatin-based chemotherapy, which could greatly reduce local tumor size and in turn facilitate the following operation by well controlling blood loss.

  8. Maternal diet and dioxin-like activity, bulky DNA adducts and micronuclei in mother–newborns

    International Nuclear Information System (INIS)

    Maternal diet can contribute to carcinogenic exposures and also modify effects of environmental exposures on maternal and fetal genetic stability. In this study, associations between maternal diet and the levels of dioxin-like plasma activity, bulky DNA adducts in white blood cells and micronuclei (MN) in lymphocytes from mother to newborns were examined. From 98 pregnant women living in the greater area of Copenhagen, Denmark in 2006–2007, maternal peripheral blood and umbilical cord blood were collected, together with information on health, environmental exposure and lifestyle. Maternal diet was estimated on the basis of maternal food frequency questionnaire (FFQ) completed by the end of pregnancy. Biomarkers were detected in paired blood samples through the dioxin-responsive chemical-activated luciferase expression (CALUX)® bioassay, 32P-postlabelling technique and cytokinesis-block MN assay. Maternal preference for meats with dark surface were significantly associated with higher bulky DNA adducts in both maternal (β 95%CI; 0.46 (0.08, 0.84)) and cord blood (β 95%CI; 0.46 (0.05, 0.86)) before and after adjustment for potential confounders. No other significant associations between the 18 dietary variables and the biomarkers measured in maternal and fetal samples were identified. The present study suggests that maternal intake of meats with dark surface contributes to the bulky DNA adduct levels in maternal and umbilical cord blood. Relationship between food preparation and bulky DNA adducts appear to be captured by a FFQ while potential associations for other biomarkers might be more complex or need larger sample size.

  9. Bulky abdominal masses in pediatrics: iconographic essay; Massas abdominais volumosas em pediatria: ensaio iconografico

    Energy Technology Data Exchange (ETDEWEB)

    Reis, Fabiano; Faria, Andreia V.; Kluge, Patricia D.; Volpato, Ricardo G.; Santos, Sergio L.M. dos; Caserta, Nelson M.G. [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Ciencias Medicas]. E-mail: fabiano97@bol.com.br

    2005-04-15

    The ultrasound, computerized tomography and magnetic resonance findings of 19 patients with abdominal bulky masses diagnosed as hydronephrosis, Wilms' tumor, neuroblastoma, adrenal carcinoma, sarcoma, hemangioendothelioma, hepatoblastoma, mesenchymal hamartoma, hepatocellular carcinoma, choledochal cyst, splenic cyst, lymphoma, enteric cyst, teratoma, hydrometrocolpos and lipoma are presented. Imaging findings (including ultrasound, computerized tomography and magnetic resonance imaging) are important tools for the evaluation of abdominal masses in pediatric patients and can contribute to the diagnosis and evaluation of the extension of these diseases. (author)

  10. Maternal diet and dioxin-like activity, bulky DNA adducts and micronuclei in mother-newborns

    Energy Technology Data Exchange (ETDEWEB)

    Pedersen, Marie, E-mail: mpedersen@creal.cat [Section of Environmental Health, Department of Public Health, University of Copenhagen, CSS, Oester Farimagsgade, Copenhagen K (Denmark); Halldorsson, Thorhallur I., E-mail: lur@ssi.dk [Faculty of Food Science and Nutrition, School of Health Sciences, University of Iceland Reykjavik (Iceland); Center for Fetal Programming, Department of Epidemiology, Statens Serum Institute, Copenhagen (Denmark); Autrup, Herman, E-mail: ha@mil.au.dk [School of Public Health, Department of Environmental and Occupational Medicine, Aarhus University, Aarhus (Denmark); Brouwer, Abraham, E-mail: Bram.Brouwer@bds.nl [BioDetection Systems B.V., Amsterdam (Netherlands); Besselink, Harrie, E-mail: Harrie.Besselink@bds.nl [BioDetection Systems B.V., Amsterdam (Netherlands); Loft, Steffen, E-mail: stl@sund.ku.dk [Section of Environmental Health, Department of Public Health, University of Copenhagen, CSS, Oester Farimagsgade, Copenhagen K (Denmark); Knudsen, Lisbeth E., E-mail: liek@sund.ku.dk [Section of Environmental Health, Department of Public Health, University of Copenhagen, CSS, Oester Farimagsgade, Copenhagen K (Denmark)

    2012-06-01

    Maternal diet can contribute to carcinogenic exposures and also modify effects of environmental exposures on maternal and fetal genetic stability. In this study, associations between maternal diet and the levels of dioxin-like plasma activity, bulky DNA adducts in white blood cells and micronuclei (MN) in lymphocytes from mother to newborns were examined. From 98 pregnant women living in the greater area of Copenhagen, Denmark in 2006-2007, maternal peripheral blood and umbilical cord blood were collected, together with information on health, environmental exposure and lifestyle. Maternal diet was estimated on the basis of maternal food frequency questionnaire (FFQ) completed by the end of pregnancy. Biomarkers were detected in paired blood samples through the dioxin-responsive chemical-activated luciferase expression (CALUX){sup Registered-Sign} bioassay, {sup 32}P-postlabelling technique and cytokinesis-block MN assay. Maternal preference for meats with dark surface were significantly associated with higher bulky DNA adducts in both maternal ({beta} 95%CI; 0.46 (0.08, 0.84)) and cord blood ({beta} 95%CI; 0.46 (0.05, 0.86)) before and after adjustment for potential confounders. No other significant associations between the 18 dietary variables and the biomarkers measured in maternal and fetal samples were identified. The present study suggests that maternal intake of meats with dark surface contributes to the bulky DNA adduct levels in maternal and umbilical cord blood. Relationship between food preparation and bulky DNA adducts appear to be captured by a FFQ while potential associations for other biomarkers might be more complex or need larger sample size.

  11. The solubility of hydrogen in rhodium, ruthenium, iridium and nickel.

    Science.gov (United States)

    Mclellan, R. B.; Oates, W. A.

    1973-01-01

    The temperature variation of the solubility of hydrogen in rhodium, ruthenium, iridium, and nickel in equilibrium with H2 gas at 1 atm pressure has been measured by a technique involving saturating the solvent metal with hydrogen, quenching, and analyzing in resultant solid solutions. The solubilities determined are small (atom fraction of H is in the range from 0.0005 to 0.00001, and the results are consistent with the simple quasi-regular model for dilute interstitial solid solutions. The relative partial enthalpy and excess entropy of the dissolved hydrogen atoms have been calculated from the solubility data and compared with well-known correlations between these quantities.

  12. Hydrogen adsorption on skeletal rhodium-tantalum electrodes-catalysts

    International Nuclear Information System (INIS)

    Skeleton rhodium-tantalic catalyst electrodes with a tantalum mass percentage of 0 to 100 have been obtained by the methodology of Crupp and others. The hydrogen adsorption is studied through the method of removing the galvano-static and potentiodynamic curves of charging in sulfuric acid and potassium hydroxide. It has been discovered that the maximum adsorption ability relatively to the hydrogen can be observed in an alloy with a 5% tantalum contents. The energetic characteristics of the alloys are higher in alkali than in acid

  13. Zirconium sulfophenylphosphonate intercalated with mineral acids

    Czech Academy of Sciences Publication Activity Database

    Svoboda, Jan; Melánová, Klára; Beneš, L.; Brus, Jiří; Casciola, M.; Donnadio, A.; Vlček, Milan; Zima, Vítězslav

    Strasbourg: European Materials Research Society, 2012. P1 2-P1 2. ISBN -. [E- MRS Spring Meeating 2012 – Symposium P Advanced Hybrid Materials II: design and applications. 14.05.2012-18.05.2012, Strasbourg] R&D Projects: GA ČR GA203/08/0208 Institutional support: RVO:61389013 Keywords : zirconium sulfophenylphosphonate * intercalation * protonic conductivity Subject RIV: CA - Inorganic Chemistry http://www.emrs-strasbourg.com/index.php?option=com_content&task=view&Itemid=132&id=479

  14. Superconducting graphite intercalation compounds with calcium

    Science.gov (United States)

    Emery, N.; Hérold, C.; Marêché, J.-F.; Lagrange, P.; Bellouard, C.; Lamura, G.; Di Gennaro, E.; Andreone, A.

    2008-04-01

    In the graphite-lithium-calcium system, four well-defined intercalation compounds were synthesised. Two of them, CaC 6 and Li 3Ca 2C 6, exhibit superconducting properties at 11.5 K and 11.15 K, respectively, the highest critical temperatures among those of graphite intercalation compounds. The samples are synthesised using a liquid-solid method allowing the preparation of pure bulk samples, auspicious for crystallographic and magnetic measurements. The crystal structure of CaC 6 was entirely specified; this compound crystallises in the R-3 m space group. The two-dimensional unit cell of Li 3Ca 2C 6 is hexagonal and commensurate with that of graphite and the intercalated sheets, very rich in metal, are seven-layered. The magnetic properties of these phases were studied with an applied field parallel and perpendicular to the graphene sheets. In both cases the magnetic phase diagram indicates that these compounds are type II superconducting materials slightly anisotropic in spite of their lamellar structure. In the case of CaC 6, in-plane magnetic penetration depth measurements show a clear exponential behaviour at low temperatures, consistent with an s-wave symmetry of the gap function, well fitted by the standard BCS theory in the dirty limit.

  15. EMI Shields made from intercalated graphite composites

    Science.gov (United States)

    Gaier, James R.; Terry, Jennifer

    1995-01-01

    Electromagnetic interference (EMI) shielding typically makes up about twenty percent of the mass of a spacecraft power system. Graphite fiber/polymer composites have significantly lower densities and higher strengths than aluminum, the present material of choice for EMI shields, but they lack the electrical conductivity that enables acceptable shielding effectiveness. Bromine intercalated pitch-based graphite/epoxy composites have conductivities fifty times higher than conventional structural graphite fibers. Calculations are presented which indicate that EMI shields made from such composites can have sufficient shielding at less than 20% of the mass of conventional aluminum shields. EMI shields provide many functions other than EMI shielding including physical protection, thermal management, and shielding from ionizing radiation. Intercalated graphite composites perform well in these areas also. Mechanically, they have much higher specific strength and modulus than aluminum. They also have shorter half thicknesses for x-rays and gamma radiation than aluminum. Thermally, they distribute infra-red radiation by absorbing and re-radiating it rather than concentrating it by reflection as aluminum does. The prospects for intercalated graphite fiber/polymer composites for EMI shielding are encouraging.

  16. Experimental application of rhodium detectors in control systems of nuclear reactors

    International Nuclear Information System (INIS)

    The theoretical basis for construction of correcting devices for eliminating the inertness of rhodium detectors is examined. The experimental application of an improved rhodium detector in the IRT-2000 Sofia reactor is described. The flow chart of its inclusion in the reactor core and connection to the control circuit is given. The results confirm the concept that the local rhodium detectors with corrected inertness can be used for control of the reactor capacity and quick-acting safety of the reactor core of WWER type reactors. 3 figs., 4 refs

  17. Asymmetric dual catalysis via fragmentation of a single rhodium precursor complex.

    Science.gov (United States)

    Song, Liangliang; Gong, Lei; Meggers, Eric

    2016-06-01

    A strategy for dual transition metal catalysis and organocatalysis is reported via the in situ disintegration of a single rhodium complex. The hereby generated chiral Lewis acid and l-β-phenylalanine synergistically catalyze the Michael addition of α,α-disubstituted aldehydes to α,β-unsaturated 2-acyl imidazoles under the formation of vicinal quaternary/tertiary stereocenters. Conveniently, the chiral-at-metal rhodium catalyst can be synthesized in just two steps starting from rhodium trichloride without the need for any chromatography. PMID:27231188

  18. De-intercalation process from Stage-1 to Stage-2 graphite intercalation compounds revisited

    Energy Technology Data Exchange (ETDEWEB)

    Chacon-Torres, J.C.; Pichler, T. [Faculty of Physics, University of Vienna, Strudlhofgasse 4, 1090 Vienna (Austria); Ganin, A.Y.; Rosseinsky, M.J. [Department of Chemistry, University of Liverpool, Liverpool L69 7ZD (United Kingdom)

    2012-12-15

    The identification and contribution of the different phonons present in the G-line Raman response in Stage-1 and Stage-2 graphite intercalation compounds (GIC) is crucial for a correct stage determination. Different factors like laser induced de-intercalation play an important role in the precise stage assignment of these phases, and their intrinsic Raman response. In this contribution, an in situ micro-Raman analysis was conducted under high-vacuum conditions. Local heating of the samples was induced by using a high laser power (8.5 mW) in order to study the de-intercalation process from Stage-1 to Stage-2 GICs. A detailed Raman line-shape analysis was performed from the recorded spectra to determine the changes from the G-line response of KC{sub 8}, CaC{sub 6}, and LiC{sub 6}. We confirmed the assignment of the broad E{sub 2g} Fano mode at {proportional_to}1510 cm{sup -1} to the intrinsic Stage-1 Raman response in GICs. Additionally, the most evident change from Stage-1 to Stage-2 was observed in an asymmetric Fano mode in the range of 1565-1610 cm{sup -1}. This mode is linked to the first-order stretching Raman mode of Graphite, which tends to increase in frequency and decrease in width as function of de-intercalation. Finally, the response of the Stage-2 phase after de-intercalation was confirmed to be a useful benchmark for the identification of the intercalation stage in highly doped GICs. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. An improved Mesri creep model for unsaturated weak intercalated soils

    Institute of Scientific and Technical Information of China (English)

    祝艳波; 余宏明

    2014-01-01

    The weak intercalated soils in redbed soft rocks of Badong formation have obvious creep characters. In order to predict the unsaturated creep behaviors of weak intercalated soils, an unsaturated creep model was established based on the unsaturated creep tests of weak intercalated soils by using GDS triaxial apparatus. The results show that the creep behaviors of intercalated soils are apparent and significantly affected by matric suction. Based on this, an empirical Mesri creep model for intercalated soils under varying matric suctions was built. The fitting results show that the parameters Ed and m of this model are in good power relations with matric suction s and stress level Dr, respectively. An improved Mesri creep model was established involving stress−matric suction−strain−time, which is more precise than the Mesri creep model in predicting the unsaturated creep behaviors of weak intercalated soils.

  20. Charge carrier density in Li-intercalated graphene

    KAUST Repository

    Kaloni, Thaneshwor P.

    2012-05-01

    The electronic structures of bulk C 6Li, Li-intercalated free-standing bilayer graphene, and Li-intercalated bilayer and trilayer graphene on SiC(0 0 0 1) are studied using density functional theory. Our estimate of Young\\'s modulus suggests that Li-intercalation increases the intrinsic stiffness. For decreasing Li-C interaction, the Dirac point shifts to the Fermi level and the associated band splitting vanishes. For Li-intercalated bilayer graphene on SiC(0 0 0 1) the splitting at the Dirac point is tiny. It is also very small at the two Dirac points of Li-intercalated trilayer graphene on SiC(0 0 0 1). For all the systems under study, a large enhancement of the charge carrier density is achieved by Li intercalation. © 2012 Elsevier B.V. All rights reserved.

  1. Synthesis and stability of Br2, ICl and IBr intercalated pitch-based graphite fibers

    Science.gov (United States)

    Wessbecher, Dorothy E.; Forsman, William C.; Gaier, James R.

    1988-01-01

    The intercalation of halogens in pitch-based fiber is studied as well as the stability of the resultant intercalation compounds. It is found that IBr intercalates P-100 to yield a high-sigma GIC with attractive stability properties. During ICl intercalation, the presence of O2 interferes with the reaction and necessitates a higher threshold pressure for intercalation.

  2. Morphological Evaluation of Variously Intercalated Pre-baked Clay

    Directory of Open Access Journals (Sweden)

    Ullah Hameed

    2014-06-01

    Full Text Available The use of porous materials is enjoying tremendous popularity and attention of the advance scientific communities due to their excellent adsorptive and catalytic activities. Clays are one of the most important candidates in the porous community which shows the above mentioned activities after modifing with a different intercalating agent. The paper is focused on the infiuence of some inorganic intercalating agents (NaOH on the morphology of the variously intercalated clay samples. The alkali metal was used as the inorganic intercalating agent. The effect of intercalation temperature, intercalation agent concentration and intercalation time on the pre-baked clay morphology were also part of the study. Scanning electron microscopy (SEM study was performed to evaluate the morphological changes of the resultant intercalates. Different morphological properties were improved significantly in the case of the inorganically modified clay samples. Thus, such intercalations are suggested to be effective if the clays under study are to be used for different industrial process at elevated conditions.

  3. External Beam Radiotherapy Followed by 90Y Ibritumomab Tiuxetan in Relapsed or Refractory Bulky Follicular Lymphoma

    International Nuclear Information System (INIS)

    Purpose: We combined external beam radiotherapy (EBRT) with yttrium-90 ibritumomab tiuxetan (90Y-IT) in an attempt to improve therapeutic response in patients with relapsed or refractory bulky follicular lymphoma (RRBFL). Methods and Materials: Between February 2006 and September 2007, 11 patients with RRBFL were treated with EBRT followed by 90Y-IT. Bulky disease (BD) was defined as >5 cm. EBRT was delivered to BD as 2,400 cGy in eight fractions using computed tomography (CT)-based planning. BD was contoured as the gross tumor volume. A planning margin of 1 to 2 cm was added depending on anatomical location. After recovery of complete blood counts (CBC), 90Y-IT was administered at a dose of 0.3 or 0.4 mCi/kg depending on platelet counts. Hematologic toxicity was monitored through weekly CBC. Response was measured by positron emission tomography/CT or CT 3-4 months after 90Y-IT. Results: Only 2 patients required prolonged breaks between EBRT and 90Y-IT. The median time after 90Y-IT for platelets to recover to >100,000/ml was 55 days (range, 41-128 days). Platelet counts for 1 patient, who had received 4 previous chemotherapy regimens, never reached 100,000/ml. The complete and overall responses to combined therapy as measured 3-4 months after 90Y-IT were 64%. No patients relapsed within the EBRT field. With a median follow-up of 36.1 months, 6 patients have relapsed, 2 of whom have died. Median progression-free survival was 17.5 months. Conclusions: In contrast to prior failure analysis data for RRBFL patients treated with 90Y-IT alone, a brief course of EBRT prevented relapse in sites of BD. EBRT used to pretreat bulky sites may improve clinical outcomes and potentially extend survival when combined with 90Y-IT.

  4. Effect of rhodium precursor on Rh/Al2O3 catalysts

    International Nuclear Information System (INIS)

    The infrared spectra of the CO/Rh/Al2O3 system have been examined following several different means of preparing the supported rhodium catalyst. Rhodium precursor materials including RhCl3 x 3H2O, Rh(NO3)3 x 2H2O, Rh6(CO)16, [Rh(OCOCH3)2]2, and Rh2(SO4)3 have been compared as to their tendencies to produce upon reduction the various CO/Rh/Al2O3 species generally attributed to this catalytic system. The nitrate and carbonyl precursors are most easily reduced to rhodium metal. The acetate and sulfate anions poison the Rh/Al2O3 surface through decomposition during reduction leading to very minimal CO adsorption. The catalytic properties of Rh/Al2O3 could be quite dependent upon the nature of rhodium precursor chosen

  5. The mechanism for the rhodium-catalyzed decarbonylation of aldehydes: A combined experimental and theoretical study

    DEFF Research Database (Denmark)

    Fristrup, Peter; Kreis, Michael; Palmelund, Anders; Norrby, Per-Ola; Madsen, Robert

    2008-01-01

    The mechanism for the rhodium-catalyzed decarbonylation of aldehydes was investigated by experimental techniques (Hammett studies and kinetic isotope effects) and extended by a computational study (DFT calculations). For both benzaldehyde and phenyl acetaldehyde derivatives, linear Hammett plots...

  6. First-principles study of hydrogen diffusion in transition metal Rhodium

    International Nuclear Information System (INIS)

    In this study, the diffuse pattern and path of hydrogen in transition metal rhodium are investigated by the first-principles calculations. Density functional theory is used to calculate the system energies of hydrogen atom occupying different positions in rhodium crystal lattice. The results indicate that the most stable position of hydrogen atom in rhodium crystal lattice locates at the octahedral interstice, and the tetrahedral interstice is the second stable site. The activation barrier energy for the diffusion of atomic hydrogen in transition metal rhodium is quantified by determining the most favorable path, i.e., the minimum-energy pathway for diffusion, that is the indirect octahedral-tetrahedral-octahedral (O-T-O) pathway, and the activation energy is 0.8345eV

  7. Intercalation and controlled release properties of vitamin C intercalated layered double hydroxide

    International Nuclear Information System (INIS)

    Two drug-inorganic composites involving vitamin C (VC) intercalated in Mg–Al and Mg–Fe layered double hydroxides (LDHs) have been synthesized by the calcination–rehydration (reconstruction) method. Powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), and UV–vis absorption spectroscopy indicate a successful intercalation of VC into the interlayer galleries of the LDH host. Studies of VC release from the LDHs in deionised water and in aqueous CO32− solutions imply that Mg3Al–VC LDH is a better controlled release system than Mg3Fe–VC LDH. Analysis of the release profiles using a number of kinetic models suggests a solution-dependent release mechanism, and a diffusion-controlled deintercalation mechanism in deionised water, but an ion exchange process in CO32− solution. - Graphical abstract: Vitamin C anions have been intercalated in the interlayer space of layered double hydroxide and released in CO32− solution and deionised water. - Highlights: • Vitamin C intercalated Mg–Al and Mg–Fe layered double hydroxides were prepared. • Release property of vitamin C in aqueous CO32− solution is better. • Avrami-Erofe’ev and first-order models provide better fit for release results. • Diffusion-controlled and ion exchange processes occur in deionised water. • An ion exchange process occurs in CO32− solution

  8. Preparation of association compound between rhodium(II) citrate and β-cyclodextrin

    International Nuclear Information System (INIS)

    Inclusion compound of rhodium(II) citrate withβ-cyclodextrin in a 1:1 molar ratio was prepared using freeze-drying method. X-ray diffractometry, thermal analysis (TG/DTG/DSC), infrared and 1H-NMR with 1H spin lattice relaxation (1H T1) measurements and 13C techniques were used to characterize the system prepared. The results indicated the formation of inclusion or association compounds between rhodium(II) citrate and β-cyclodextrin. (author)

  9. Investigation of surface layer composition of the rhodium-ruthenium catalysts by means of auger spectroscopy

    International Nuclear Information System (INIS)

    The surface layer composition of skeleton catalysts of the rhodium-ruthenium system by means of Auger-electron spectroscopy and electron spectroscopy for the chemical analysis is investigated. It is shown that apart from rhodium, ruthenium aluminium and silicon there is a certain quantity of chemosorbed oxygen accumulated in case of catalysts conservation over a long period of time. The dependence of filling catalysts by chemosorbed oxygen on the alloy composition has been found

  10. Diversity synthesis using the complimentary reactivity of rhodium(II)- and palladium(II)-catalyzed reactions.

    Science.gov (United States)

    Ni, Aiwu; France, Jessica E; Davies, Huw M L

    2006-07-21

    Rhodium(II)-catalyzed reactions of aryldiazoacetates can be conducted in the presence of iodide, triflate, organoboron, and organostannane functionality, resulting in the formation of a variety of cyclopropanes or C-H insertion products with high stereoselectivity. The combination of the rhodium(II)-catalyzed reaction with a subsequent palladium(II)-catalyzed Suzuki coupling offers a novel strategy for diversity synthesis. PMID:16839138

  11. Gibbs free energy of formation of rhodium sulfides

    International Nuclear Information System (INIS)

    Highlights: • Gibbs energies of formation of RhS0.882, Rh3S4 and Rh2S3 are accurately measured. • Employed a novel solid-state cell based on single crystal CaF2 as an electrolyte. • Auxiliary electrodes of (CaS + CaF2) convert S2 potential into F2 potential. • Measuring electrodes consists of two adjacent phases in the system (Rh + S). • Evaluated S298.15Ko and ΔfH298.15Ko for three rhodium sulfides at T = 298.15 K. -- Abstract: Using a solid-state electrochemical technique, thermodynamic properties of three sulfide phases (RhS0.882, Rh3S4, Rh2S3) in the binary system (Rh + S) are measured as a function of temperature over the range from (925 to 1275) K. Single crystal CaF2 is used as the electrolyte. The auxiliary electrode consisting of (CaS + CaF2) is designed in such a way that the sulfur chemical potential converts into an equivalent fluorine potential at each electrode. The sulfur potentials at the measuring electrodes are established by the mixtures of (Rh + RhS0.882), (RhS0.882 + Rh3S4) and (Rh3S4 + Rh2S3) respectively. A gas mixture (H2 + H2S + Ar) of known composition fixes the sulfur potential at the reference electrode. A novel cell design with physical separation of rhodium sulfides in the measuring electrode from CaS in the auxiliary electrode is used to prevent interaction between the two sulfide phases. They equilibrate only via the gas phase in a hermetically sealed reference enclosure. Standard Gibbs energy changes for the following reactions are calculated from the electromotive force of three cells:2.2667Rh (s) + S2 (g) → 2.2667RhS0.882 (s), ΔrGo±2330/(J·mol-1)=-288690+146.18(T/K), 4.44RhS0.882 (s) + S2 (g) → 1.48Rh3S4 (s), ΔrGo±2245/(J·mol-1)=-245596+164.31(T/K), 4Rh3S4 (s) + S2 (g) → 6Rh2S3 (s), ΔrGo±2490/(J·mol-1)=-230957+160.03(T/K). Standard entropy and enthalpy of formation of rhodium sulfides from elements in their normal standard states at T = 298.15 K are evaluated

  12. Investigation of the Electrocatalytic Activity of Rhodium Sulfide for Hydrogen Evolution and Hydrogen Oxidation

    International Nuclear Information System (INIS)

    We report the synthesis of unsupported and carbon-supported, mixed phase, rhodium sulfide, using both a hydrogen sulfide source and a solid sulfur source. Samples with several different distributions of rhodium sulfide phases (Rh2S3, Rh17S15, RhS2 and metallic Rh) were obtained by varying the temperature and exposure time to H2S or sulfur to rhodium ratio when using solid sulfur. Samples were characterized by X-ray diffraction (XRD), and the unsupported rhodium sulfide compounds studied using Raman spectroscopy to link Raman spectra to catalyst phases. The electrocatalytic activity of the rhodium sulfide compounds for hydrogen evolution and oxidation was measured using rotating disk electrode measurements in acidic conditions to simulate use in a flow cell. The most active phases for hydrogen evolution were found to be Rh3S4 and Rh17S15 (−0.34 V vs. Ag/AgCl required for 20 mA/cm2), while Rh2S3 and RhS2 phases were relatively inactive (−0.46 V vs. Ag/AgCl required for 20 mA/cm2 using RhS2/C). The hydrogen oxidation activity of all rhodium sulfide phases is significantly lower than the hydrogen evolution activity and is not associated with conductivity limitations

  13. Benzenesulfonamides incorporating bulky aromatic/heterocyclic tails with potent carbonic anhydrase inhibitory activity.

    Science.gov (United States)

    Bozdag, Murat; Alafeefy, Ahmed M; Vullo, Daniela; Carta, Fabrizio; Dedeoglu, Nurcan; Al-Tamimi, Abdul-Malek S; Al-Jaber, Nabila A; Scozzafava, Andrea; Supuran, Claudiu T

    2015-12-15

    Three series of sulfonamides incorporating long, bulky tails were obtained by applying synthetic strategies in which substituted anthranilic acids, quinazolines and aromatic sulfonamides have been used as starting materials. They incorporate long, bulky diamide-, 4-oxoquinazoline-3-yl- or quinazoline-4-yl moieties in their molecules, and were investigated for the inhibition of four physiologically relevant carbonic anhydrase (CA, EC 4.2.1.1) isoforms, the cytosolic human (h) hCA I and II, as well as the transmembrane hCA IX and XII. Most of the new sulfonamides showed excellent inhibitory effects against the four isoforms, with KIs of 7.6-322nM against hCA I, of 0.06-85.4nM against hCA II; of 6.7-152nM against hCA IX and of 0.49-237nM against hCA XII; respectively. However no relevant isoform-selective behavior has been observed for any of them, although hCA II and XII, isoforms involved in glaucoma-genesis were the most inhibited ones. The structure-activity relationship for inhibiting the four CAs with these derivatives is discussed in detail. PMID:26639945

  14. Improved control of bulky prostate carcinoma with sequential estrogen and radiation therapy

    International Nuclear Information System (INIS)

    Patients with bulky prostate cancer have usually been treated by palliative measures because the likelihood of tumor control with definitive irradiation has been low and the development of distant metastases high. The addition of estrogen to irradiation has not been shown to be of value. However, the method of estrogen administration may have been the cause for the apparent lack of benefit. In this study estrogen was used for two months prior to and concurrent with irradiation. Between 1975 and 1980, 25 patients with bulky prostate cancer received sequential estrogen and irradiation, 12 patients irradiation alone and six patients irradiation after having become refractory to long-term estrogen use. Eighteen of 25 (72%) treated by sequential estrogen and irradiation, 14/17 (82%) with estrogen responsive cancer and 4/8 (50%) with estrogen resistant cancer had a complete tumor response. Six of 11 (55%) patients treated by irradiation alone and 2/6 (33%) treated by irradiation for estrogen refractory cancer had a complete tumor response. Distant metastases was observed in 15% of patients when the primary tumor was controlled and 30% when there was persistent or recurrent local disease. The results with the use of estrogen prior to and concurrent with irradiation is encouraging. Estrogen may shrink the cancer and allow for a more favorable geometry for external irradiation

  15. Bulky Macroporous TiO2 Photocatalyst with Cellular Structure via Facile Wood-Template Method

    Directory of Open Access Journals (Sweden)

    Qingfeng Sun

    2013-01-01

    Full Text Available We report a bulky macroporous TiO2 particles with cellular structure prepared in the presence of wood slices as template. Firstly, TiO2 sol was coated onto the wood slices by repeated dip-coating process. Then, after calcinations at 550°C, the wood template could be removed, and the bulky TiO2 structure was obtained. The prepared samples were characterized by scanning electron microscopy (SEM, X-ray diffraction (XRD, energy dispersive spectroscopy (EDS, and transmission electron microscope (TEM techniques. XRD pattern confirmed the crystalline phase of the wood-templated TiO2 is anatase phase. And interestingly, from the observation of SEM image, the wood-templated TiO2 inherited the initial cellular structures of birch lumber (B. albosinensis Burk, and numerous macropores were observed in the sample. Meanwhile, the wood-templated TiO2 presented a superior photocatalytic ability to decompose Rhodamine B (RhB under ultraviolet irradiation.

  16. Catalytic Degradation of Sulfur Hexafluoride by Rhodium Complexes.

    Science.gov (United States)

    Zámostná, Lada; Braun, Thomas

    2015-09-01

    The development of a safe and efficient method for the degradation of SF6 is of current environmental interest, because SF6 is one of the most potent greenhouse gases. SF6 is thermally and chemically extremely inert, and therefore, it has been used in various industrial applications. However, this inertness results in a major challenge for its depletion. We report on a process for a catalytic degradation of SF6 in the homogeneous phase by using rhodium complexes as precatalysts. The SF6 activation reactions feature mild reaction conditions, low catalyst loadings, and a high selectivity. The employment of phosphines and hydrosilanes for scavenging the sulfur and fluorine atoms of the SF6 molecule allows the selective transformation of SF6 into nongaseous and nontoxic compounds. PMID:26190201

  17. Superconductivity in alkali metal intercalated iron selenides.

    Science.gov (United States)

    Krzton-Maziopa, A; Svitlyk, V; Pomjakushina, E; Puzniak, R; Conder, K

    2016-07-27

    Alkali metal intercalated iron selenide superconductors A x Fe2-y Se2 (where A  =  K, Rb, Cs, Tl/K, and Tl/Rb) are characterized by several unique properties, which were not revealed in other superconducting materials. The compounds crystallize in overall simple layered structure with FeSe layers intercalated with alkali metal. The structure turned out to be pretty complex as the existing Fe-vacancies order below ~550 K, which further leads to an antiferromagnetic ordering with Néel temperature fairly above room temperature. At even lower temperatures a phase separation is observed. While one of these phases stays magnetic down to the lowest temperatures the second is becoming superconducting below ~30 K. All these effects give rise to complex relationships between the structure, magnetism and superconductivity. In particular the iron vacancy ordering, linked with a long-range magnetic order and a mesoscopic phase separation, is assumed to be an intrinsic property of the system. Since the discovery of superconductivity in those compounds in 2010 they were investigated very extensively. Results of the studies conducted using a variety of experimental techniques and performed during the last five years were published in hundreds of reports. The present paper reviews scientific work concerning methods of synthesis and crystal growth, structural and superconducting properties as well as pressure investigations. PMID:27248118

  18. Comparison of lithium and sodium intercalation materials

    Directory of Open Access Journals (Sweden)

    Vujković Milica

    2015-01-01

    Full Text Available Low abundance of lithium in Earth’s crust and its high participation in overall cost of lithium-ion batteries incited intensive investigation of sodium-ion batteries, in hope that they may become similar in basic characteristics: specific energy and specific power. Furthermore, over the last years the research has been focused on the replacement of organic electrolytes of Li- and Na-ion batteries, by aqueous electrolytes, in order to simplify the production and improve safety of use. In this lecture, some recent results on the selected intercalation materials are presented: layered structure vanadium oxides, olivine and nasicon phosphates, potentially usable in both Li and Na aqueous rechargeable batteries. After their characterization by X-ray diffraction and electron microscopy, the electrochemical behavior was studied by both cyclic voltammetry and hronopotenciometry. By comparing intercalation kinetics and coulombic capacity of these materials in LiNO3 and NaNO3 solutions, it was shown that the following ones: Na1.2V3O8, Na2V6O16/C , NaFePO4/C and NaTi2(PO43/C may be used as electrode materials in aqueous alkali-ion batteries.

  19. Superconductivity in alkali metal intercalated iron selenides

    Science.gov (United States)

    Krzton-Maziopa, A.; Svitlyk, V.; Pomjakushina, E.; Puzniak, R.; Conder, K.

    2016-07-01

    Alkali metal intercalated iron selenide superconductors A x Fe2‑y Se2 (where A  =  K, Rb, Cs, Tl/K, and Tl/Rb) are characterized by several unique properties, which were not revealed in other superconducting materials. The compounds crystallize in overall simple layered structure with FeSe layers intercalated with alkali metal. The structure turned out to be pretty complex as the existing Fe-vacancies order below ~550 K, which further leads to an antiferromagnetic ordering with Néel temperature fairly above room temperature. At even lower temperatures a phase separation is observed. While one of these phases stays magnetic down to the lowest temperatures the second is becoming superconducting below ~30 K. All these effects give rise to complex relationships between the structure, magnetism and superconductivity. In particular the iron vacancy ordering, linked with a long-range magnetic order and a mesoscopic phase separation, is assumed to be an intrinsic property of the system. Since the discovery of superconductivity in those compounds in 2010 they were investigated very extensively. Results of the studies conducted using a variety of experimental techniques and performed during the last five years were published in hundreds of reports. The present paper reviews scientific work concerning methods of synthesis and crystal growth, structural and superconducting properties as well as pressure investigations.

  20. Intercalation of optically active pyridines into layered phosphates and phosphonates

    Czech Academy of Sciences Publication Activity Database

    Zima, Vítězslav; Bureš, F.; Melánová, Klára; Cvejn, D.; Svoboda, Jan; Beneš, L.

    Strasbourg : University of Strasbourg, Francie, 2015. O25. [International Symposium on Intercalation Compounds. 31.05.2015-04.06.2015, Strasbourg] R&D Projects: GA ČR(CZ) GA13-01061S Institutional support: RVO:61389013 Keywords : intercalation * nonlinear optics * prosphonates Subject RIV: CA - Inorganic Chemistry

  1. Layered metal phosphonates as hosts in intercalation chemistry

    Czech Academy of Sciences Publication Activity Database

    Zima, Vítězslav; Beneš, L.; Melánová, Klára; Svoboda, Jan

    Sendai : Tohoku University, 2013. 1-8-1-8. ISBN N. [17th International Symposium on Intercalation Compounds. 12.05.2013-16.05.2013, Sendai] Institutional support: RVO:61389013 Keywords : metal phosphonates * layered materials * intercalation chemistry Subject RIV: CA - Inorganic Chemistry

  2. Superconductivity in the alkali metal intercalates of molybdenum disulphide

    Science.gov (United States)

    Somoano, R. B.; Hadek, V.; Rembaum, A.

    1972-01-01

    The complete series of alkali metals, lithium through cesium, have been intercalated into molybdenum disulphide, using both the liquid ammonia and vapor techniques. All the intercalates with the exception of lithium yielded full superconducting transitions with onset temperatures of 6 K for AxMoS2(Ax=K,Rb,Cs) and 4 K for BxMoS2(Bx=Li,Na). The superconducting transition for lithium was incomplete down to 1.5 K. Stoichiometries and unit cell parameters have been determined for the intercalation compounds. Both rhombohedral and hexagonal polymorphs of MoS2 have been intercalated and found to exhibit the same superconductivity behavior. The nature of the extraneous superconducting transition of some intercalated samples on exposure to air was elucidated.

  3. New Conditions for Intercalation of Organic Compounds into Semiconductor Nanomaterial

    Institute of Scientific and Technical Information of China (English)

    A.A.El-Meligi

    2009-01-01

    The intercalation of organic guests, 2-methyl pyridine (2-picoline) and 3-methyl pyridine (3-picoline) into semiconductor layered nanomaterial (MnPS3) was investigated. New conditions were applied. New phases appeared and lattice expansions were 0.36 nm for 2-picoline intercalation and 0.728 nm for 3-picoline intercalation. The XRD (X- ray diffraction) patterns exhibit sharp hkl reflections confirming that the material is highly crystalline. The interlayer gap (0.64 nm) of the host plays a role for the arrangement of the guest in the interlayer region. The crystal structure of the MnPS3 was indexed in the monoclinic system before intercalation. After intercalation, the crystal system was indexed in the trigonal unit cell. The lattice parameters were obtained and c-axis value was related to the (001) reflections.

  4. K-intercalated carbon systems: Effects of dimensionality and substrate

    KAUST Repository

    Kaloni, Thaneshwor P.

    2012-06-01

    Density functional theory is employed to investigate the electronic properties of K-intercalated carbon systems. Young\\'s modulus indicates that the intercalation increases the intrinsic stiffness. For K-intercalated bilayer graphene on SiC(0001) the Dirac cone is maintained, whereas a trilayer configuration exhibits a small splitting at the Dirac point. Interestingly, in contrast to many other intercalated carbon systems, the presence of the SiC(0001) substrate does not suppress but rather enhances the charge carrier density. Reasonably high values are found for all systems, the highest carrier density for the bilayer. The band structure and electron-phonon coupling of free-standing K-intercalated bilayer graphene points to a high probability for superconductivity in this system. © 2012 Europhysics Letters Association.

  5. Quasi-freestanding graphene on Ni(111) by Cs intercalation

    KAUST Repository

    Alattas, M.

    2016-05-26

    A possible approach to achieve quasi-freestanding graphene on a substrate for technological purpose is the intercalation of alkali metal atoms. Cs intercalation between graphene and Ni(111) therefore is investigated using density functional theory, incorporating van der Waals corrections. It is known that direct contact between graphene and Ni(111) perturbs the Dirac states. We find that Cs intercalation restores the linear dispersion characteristic of Dirac fermions, which agrees with experiments, but the Dirac cone is shifted to lower energy, i.e., the graphene sheet is n-doped. Cs intercalation therefore decouples the graphene sheet from the substrate except for a charge transfer. On the other hand, the spin polarization of Ni(111) does not extend through the intercalated atoms to the graphene sheet, for which we find virtually spin-degeneracy.

  6. Quasi-freestanding graphene on Ni(111) by Cs intercalation

    Science.gov (United States)

    Alattas, M.; Schwingenschlögl, U.

    2016-05-01

    A possible approach to achieve quasi-freestanding graphene on a substrate for technological purpose is the intercalation of alkali metal atoms. Cs intercalation between graphene and Ni(111) therefore is investigated using density functional theory, incorporating van der Waals corrections. It is known that direct contact between graphene and Ni(111) perturbs the Dirac states. We find that Cs intercalation restores the linear dispersion characteristic of Dirac fermions, which agrees with experiments, but the Dirac cone is shifted to lower energy, i.e., the graphene sheet is n-doped. Cs intercalation therefore decouples the graphene sheet from the substrate except for a charge transfer. On the other hand, the spin polarization of Ni(111) does not extend through the intercalated atoms to the graphene sheet, for which we find virtually spin-degeneracy.

  7. High pressure measurement of the uniaxial stress of host layers on intercalants and staging transformation of intercalation compounds

    CERN Document Server

    Park, T R; Kim, H; Min, P

    2002-01-01

    A layered double-hydroxide intercalation compound was synthesized to measure the uniaxial stress the host layers exert on the intercalants. To measure the uniaxial stress, we employed the photoluminescence (PL) from the intercalated species, the Sm ion complex, as it is sensitive to the deformation of the intercalants. Of the many PL peaks the Sm ion complex produces, the one that is independent of the counter-cation environment was chosen for the measurement since the Sm ion complexes are placed under a different electrostatic environment after intercalation. The peak position of the PL was redshifted linearly with increasing hydrostatic pressure on the intercalated sample. Using this pressure-induced redshifting rate and the PL difference at ambient pressure between the pre-intercalation and the intercalated ions, we found that, in the absence of external pressure, the uniaxial stress exerted on the samarium ion complexes by the host layers was about 13.9 GPa at room temperature. Time-resolved PL data also ...

  8. Catalytic behaviour in the ring-opening polymerisation of organoaluminiums supported by bulky heteroscorpionate ligands.

    Science.gov (United States)

    Castro-Osma, Jose A; Alonso-Moreno, Carlos; Lara-Sánchez, Agustín; Otero, Antonio; Fernández-Baeza, Juan; Sánchez-Barba, Luis F; Rodríguez, Ana M

    2015-07-21

    A series of alkyl organoaluminium complexes based on bulky heteroscorpionate ligands were designed as catalysts for the ring-opening polymerisation of cyclic esters. Thus, the treatment of AlX3 (X = Me, Et) with bulky acetamide or thioacetamide heteroscorpionate ligands nbptamH (1) [nbptamH = N-naphthyl-2,2-bis(3,5-dimethylpyrazol-1-yl)thioacetamide], fbpamH (2) [fbpamH = N-fluorenyl-2,2-bis(3,5-dimethylpyrazol-1-yl)acetamide], ptbptamH (3) [ptbptamH = N-phenyl-2,2-bis(3,5-di-tert-butylpyrazol-1-yl)thioacetamide], ntbptamH (4) [ntbptamH = N-naphthyl-2,2-bis(3,5-di-tert-butylpyrazol-1-yl)thioacetamide], ptbpamH (5) [ptbpamH = N-phenyl-2,2-bis(3,5-di-tert-butylpyrazol-1-yl)acetamide] and (S)-mtbpamH (6) [(S)-mtbpamH = (S)-(−)-N-α-methylbenzyl-2,2-bis(3,5-di-tert-butylpyrazol-1-yl)acetamide] for 1 hour at 0 °C afforded the dialkyl aluminium complexes [AlX2{κ(2)-nbptam}] (X = Me 7, Et 8), [AlX2{κ(2)-fbpam}] (X = Me 9, Et 10), [AlX2{κ(2)-ptbptam}] (X = Me 11, Et 12), [AlX2{κ(2)-ntbptam}] (X = Me 13, Et 14), [AlX2{κ2(-)ptbpam}] (X = Me 15, Et 16) and [AlX2{κ(2)-(S)-mtbpam}] (X = Me 17, Et 18). The structures of the complexes were determined by spectroscopic methods and the X-ray crystal structure of 14 was also established. The alkyl-containing aluminium complexes 7–18 can act as efficient single-component initiators for the ring-opening polymerisation of ε-caprolactone and rac-lactide. The polymerisations are living, as evidenced by the narrow polydispersities of the isolated polymers and the linear nature of the number average molecular weight versus conversion plot. Finally, a comparative study of ring-opening polymerisation for new bulky heteroscorpionate aluminium initiators and the less congested aluminium analogues is reported. PMID:25534594

  9. Intercalation and controlled release properties of vitamin C intercalated layered double hydroxide

    Science.gov (United States)

    Gao, Xiaorui; Lei, Lixu; O'Hare, Dermot; Xie, Juan; Gao, Pengran; Chang, Tao

    2013-07-01

    Two drug-inorganic composites involving vitamin C (VC) intercalated in Mg-Al and Mg-Fe layered double hydroxides (LDHs) have been synthesized by the calcination-rehydration (reconstruction) method. Powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), and UV-vis absorption spectroscopy indicate a successful intercalation of VC into the interlayer galleries of the LDH host. Studies of VC release from the LDHs in deionised water and in aqueous CO32- solutions imply that Mg3Al-VC LDH is a better controlled release system than Mg3Fe-VC LDH. Analysis of the release profiles using a number of kinetic models suggests a solution-dependent release mechanism, and a diffusion-controlled deintercalation mechanism in deionised water, but an ion exchange process in CO32- solution.

  10. Intercalation and controlled release properties of vitamin C intercalated layered double hydroxide

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Xiaorui, E-mail: gxr_1320@sina.com [College of Science, Hebei University of Engineering, Handan 056038 (China); School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189 (China); Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA (United Kingdom); Lei, Lixu [School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189 (China); O' Hare, Dermot [Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA (United Kingdom); Xie, Juan [College of Science, Hebei University of Engineering, Handan 056038 (China); Gao, Pengran [School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189 (China); Chang, Tao [College of Science, Hebei University of Engineering, Handan 056038 (China)

    2013-07-15

    Two drug-inorganic composites involving vitamin C (VC) intercalated in Mg–Al and Mg–Fe layered double hydroxides (LDHs) have been synthesized by the calcination–rehydration (reconstruction) method. Powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), and UV–vis absorption spectroscopy indicate a successful intercalation of VC into the interlayer galleries of the LDH host. Studies of VC release from the LDHs in deionised water and in aqueous CO{sub 3}{sup 2−} solutions imply that Mg{sub 3}Al–VC LDH is a better controlled release system than Mg{sub 3}Fe–VC LDH. Analysis of the release profiles using a number of kinetic models suggests a solution-dependent release mechanism, and a diffusion-controlled deintercalation mechanism in deionised water, but an ion exchange process in CO{sub 3}{sup 2−} solution. - Graphical abstract: Vitamin C anions have been intercalated in the interlayer space of layered double hydroxide and released in CO{sub 3}{sup 2−} solution and deionised water. - Highlights: • Vitamin C intercalated Mg–Al and Mg–Fe layered double hydroxides were prepared. • Release property of vitamin C in aqueous CO{sub 3}{sup 2−} solution is better. • Avrami-Erofe’ev and first-order models provide better fit for release results. • Diffusion-controlled and ion exchange processes occur in deionised water. • An ion exchange process occurs in CO{sub 3}{sup 2−} solution.

  11. Alkali-metal intercalation in carbon nanotubes

    Science.gov (United States)

    Béguin, F.; Duclaux, L.; Méténier, K.; Frackowiak, E.; Salvetat, J. P.; Conard, J.; Bonnamy, S.; Lauginie, P.

    1999-09-01

    We report on successful intercalation of multiwall (MWNT) and single wall (SWNT) carbon nanotubes with alkali metals by electrochemical and vapor phase reactions. A LiC10 compound was produced by full electrochemical reduction of MWNT. KC8 and CsC8-MWNT first stage derivatives were synthesized in conditions of alkali vapor saturation. Their identity periods and the 2×2 R 0° alkali superlattice are comparable to their parent graphite compounds. The dysonian shape of KC8 EPR line and the temperature-independent Pauli susceptibility are both characteristic of a metallic behavior, which was confirmed by 13C NMR anisotropic shifts. Exposure of SWNT bundles to alkali vapor led to an increase of the pristine triangular lattice from 1.67 nm to 1.85 nm and 1.87 nm for potassium and rubidium, respectively.

  12. Intercalation compounds involving inorganic layered structures

    Directory of Open Access Journals (Sweden)

    CONSTANTINO VERA R. L.

    2000-01-01

    Full Text Available Two-dimensional inorganic networks can shown intracrystalline reactivity, i.e., simple ions, large species as Keggin ions, organic species, coordination compounds or organometallics can be incorporated in the interlayer region. The host-guest interaction usually causes changes in their chemical, catalytic, electronic and optical properties. The isolation of materials with interesting properties and making use of soft chemistry routes have given rise the possibility of industrial and technological applications of these compounds. We have been using several synthetic approaches to intercalate porphyrins and phthalocyanines into inorganic materials: smectite clays, layered double hydroxides and layered niobates. The isolated materials have been characterized by elemental and thermal analysis, X-ray diffraction, surface area measurements, scanning electronic microscopy, electronic and resonance Raman spectroscopies and EPR. The degree of layer stacking and the charge density of the matrices as well their acid-base nature were considered in our studies on the interaction between the macrocycles and inorganic hosts.

  13. Fabricating graphene devices from graphite intercalation compounds

    Science.gov (United States)

    Yagi, Ryuta; Shimomura, Midori; Tahara, Fumiya; Fukada, Seiya

    2013-03-01

    We report a method of making few-layer graphene flakes by mechanically exfoliating SbCl5-graphite intercalation compounds (GICS). The number of exfoliated graphene flakes had a peculiar distribution relevant to the stage structure of GICs. The carrier doping of the few-layer graphene flakes was about two orders of magnitude smaller than that expected from the stoichiometry of the GICs. The measured electric mobility was comparable to that made from pristine graphite. The EPMA measurement showed that inhomogeneous distribution of dopant near the surface of GIC was responsible for obtaining the virtually undoped graphene. Deintercalation of dopant would expand interlayer distance of each graphene layer, and thereby layer-number of exfoliated graphene depended stage number of GIC.

  14. Maternal diet and dioxin-like activity, bulky DNA adducts and micronuclei in mother-newborns

    DEFF Research Database (Denmark)

    Pedersen, Marie; Halldorsson, Thorhallur I; Autrup, Herman;

    2012-01-01

    Maternal diet can contribute to carcinogenic exposures and also modify effects of environmental exposures on maternal and fetal genetic stability. In this study, associations between maternal diet and the levels of dioxin-like plasma activity, bulky DNA adducts in white blood cells and micronuclei...... (MN) in lymphocytes from mother to newborns were examined. From 98 pregnant women living in the greater area of Copenhagen, Denmark in 2006-2007, maternal peripheral blood and umbilical cord blood were collected, together with information on health, environmental exposure and lifestyle. Maternal diet...... was estimated on the basis of maternal food frequency questionnaire (FFQ) completed by the end of pregnancy. Biomarkers were detected in paired blood samples through the dioxin-responsive chemical-activated luciferase expression (CALUX)(®) bioassay, (32)P-postlabelling technique and cytokinesis...

  15. Synthesis and characterization of bulky mesoporous silica Pd-MCM-41

    International Nuclear Information System (INIS)

    Bulky palladium catalyst supported on mesoporous silica MCM-41 (Pd-MCM-41) was successfully synthesized by hydrothermal hot-pressing method. In this study, the structure of the palladium species in Pd-MCM-41 bulk before and after heat-treatment process was revealed by X-ray diffraction (XRD), X-ray absorption near edge structure (XANES) and transmission electron microscopy (TEM). Also, the microstructure and mesoporous property of Pd-MCM-41 bulk was discussed. As a result, it was revealed that these dense Pd-MCM-41 bulks possessed a high surface area of over 1000 m2/g and the structure of palladium of Pd-MCM-41 bulk is almost equal to palladium (0) metal. (author)

  16. Distance-Dependent Attractive and Repulsive Interactions of Bulky Alkyl Groups.

    Science.gov (United States)

    Hwang, Jungwun; Li, Ping; Smith, Mark D; Shimizu, Ken D

    2016-07-01

    The stabilizing and destabilizing effects of alkyl groups on an aromatic stacking interaction were experimentally measured in solution. The size (Me, Et, iPr, and tBu) and position (meta and para) of the alkyl groups were varied in a molecular balance model system designed to measure the strength of an intramolecular aromatic interaction. Opposite stability trends were observed for alkyl substituents at different positions on the aromatic rings. At the closer meta-position, smaller groups were stabilizing and larger groups were destabilizing. Conversely, at the farther para-position, the larger alkyl groups were systematically more stabilizing with the bulky tBu group forming the strongest stabilizing interaction. X-ray crystal structures showed that the stabilizing interactions of the small meta-alkyl and large para-alkyl groups were due to their similar distances and van der Waals contact areas with the edge of opposing aromatic ring. PMID:27159670

  17. Photoinduced and thermal denitrogenation of bulky triazoline crystals: insights into solid-to-solid transformation.

    Science.gov (United States)

    de Loera, Denisse; Stopin, Antoine; Garcia-Garibay, Miguel A

    2013-05-01

    The photoinduced and thermal denitrogenation of crystalline triazolines with bulky substituents leads to the quantitative formation of aziridines in clean solid-to-solid reactions despite very large structural changes in the transition from reactant to product. Analysis of the reaction progress by powder X-ray diffraction, solid-state (13)C CPMAS NMR, solid-state FTIR spectroscopy, and thermal analysis has revealed that solid-to-solid reactions proceed either through metastable phases susceptible to amorphization or by mechanisms that involve a reconstructive phase transition that culminates in the formation of the stable phase of the product. While the key for a solid-to-solid transformation is that the reaction occurs below the eutectic temperature of the reactant and product two-component system, experimental evidence suggests that those reactions will undergo a reconstructive phase transition when they take place above the glass transition temperature. PMID:23547729

  18. Lifestyle, Environmental, and Genetic Predictors of Bulky DNA Adducts in a Study Population Nested within a Prospective Danish Cohort

    DEFF Research Database (Denmark)

    Eriksen, K. T.; Sørensen, M.; Autrup, H.;

    2010-01-01

    Danish cohort. At enrollment, blood samples were collected and information on lifestyle, including dietary and smoking habits, obtained. Previously, bulky DNA adducts were measured in 245 individuals who developed lung cancer and 255 control members of the cohort. Of these 500 individuals, data on 375...... individuals were included in this study, excluding 125 cases, which developed lung cancer within the first 3 yr after blood sampling. Bulky DNA adduct levels were measured by 32P-postlabeling technique and polymorphisms in carcinogen metabolism and DNA repair genes were determined. Potential predictors of...

  19. Synthesis and Electroluminescent Properties of Julolidine-π-Juloidine Type Materials with the Bulky Adamantane Groups

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kum Hee; Yoon, Seung Soo [Sungkyunkwan Univ., Suwon (Korea, Republic of); Lee, Seok Jae; Kim, Young Kwan [Hongik Univ., Seoul (Korea, Republic of)

    2012-11-15

    A main problem of red emitting material, which contributes to their low EL performances, is the concentration quenching due to the effective self aggregation and the consequent formation of excimers. To avoid this drawback and thus improve the EL properties of red fluorescent OLED devices, many synthetic efforts have been conducted to develop new emitting materials with the structural motifs to suppress self-aggregation by the weakening intermolecular attractive interactions. Particularly, the introduction of bulky moieties in the emitters would provide the steric hindrance between emitting materials in solid state devices and thus reduce the self-aggregation. Nevertheless, EL performances of red materials still need to be improved for the practical applications. In conclusion, we designed and synthesized three julolidine-π-juloidine type emitting materials (1-3) with the bulky adamantane groups. To study their electroluminescent properties, the multilayered OLED devices with the structure of ITO/NPB (40 nm)/ADN : 1-3 (x%) (20 nm)/Alq{sub 3} (40 nm)/Liq (2 nm)/Al were fabricated. All devices using emitters 1-3 showed the efficient emissions, in which their EL performances depend on the structure of emitters sensitively. Particularly, a device using emitter 3 exhibited the efficient orange-red emission with the luminous and power efficiencies of 4.79 cd/A and 1.76 lm/W at 20 mA/cm{sup 2}, respectively. The CIE coordinates of this device was (0.57, 0.42) at 7.0 V.

  20. Synthesis and characterization of Mn intercalated Mg-Al hydrotalcite.

    Science.gov (United States)

    Yang, Chengxue; Liao, Libing; Lv, Guocheng; Wu, Limei; Mei, Lefu; Li, Zhaohui

    2016-10-01

    Mn intercalated hydrotalcite was prepared using a reconstruction method. And Mn intercalation was confirmed by XRD, FTIR, and thermal analyses. The different valences of Mn were present as determined by XPS. Calcination slightly promoted the isomorphic replacement of Mn(2+) and Mn(3+) for Mg(2+) and Al(3+), especially the replacement of Mn(2+) for Mg(2+) and Al(3+), and to some extent, reduced Mn intercalation. Ultrasonic treatment significantly increased Mn intercalation in permanganate form (Mn(7+)), and promoted the replacement of Mn(2+) for Mg(2+) and Al(3+). XRF analysis showed that ultrasonic treatment decreased the unbalanced layer charge of Mn intercalated hydrotalcite, while prolonged calcination increased it. These results may provide guidance on the preparation and application of Mn intercalated hydrotalcite. Extended calcination time and ultrasonic vibration increased the interlayer spacing of hydrotalcite, as a result of reduction in layer charge. As the layer charge was not completely balanced after Mn intercalation, a certain amount of CO3(2-) was re-adsorbed into the interlayer space. Mn-hydrotalcites with different layer charges, different contents of Mn with varying valences are expected to have different performances in the process of adsorption, degradation, and catalysis. PMID:27380016

  1. Rhodium mediated bond activation: from synthesis to catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Ho, Hung-An [Iowa State Univ., Ames, IA (United States)

    2012-01-01

    Recently, our lab has developed monoanionic tridentate ligand, ToR, showing the corresponding coordination chemistry and catalyst reactivity of magnesium, zirconium, zinc and iridium complexes. This thesis details synthetic chemistry, structural study and catalytic reactivity of the ToR-supported rhodium compounds. Tl[ToR] has been proved to be a superior ligand transfer agent for synthesizing rhodium complexes. The salt metathesis route of Tl[ToM] with [Rh(μ-Cl)(CO)]2 and [Rh(μ- Cl)(COE)]2 gives ToMRh(CO)2 (2.2) and ToMRhH(β3-C8H13) (3.1) respectively while Tl[ToM] with [Rh(μ-Cl)(CO)]2 affords ToPRh(CO)2 (2.3). 2.2 reacts with both strong and weak electrophiles, resulting in the oxazoline N-attacked and the metal center-attacked compounds correspondingly. Using one of the metal center-attacked electrophiles, 2.3 was demonstrated to give high diastereoselectivity. Parallel to COE allylic C-H activation complex 3.1, the propene and allylbenzene allylic C-H activation products have also been synthesized. The subsequent functionalization attempts have been examined by treating with Brønsted acids, Lewis acids, electrophiles, nucleophiles, 1,3-dipolar reagents and reagents containing multiple bonds able to be inserted. Various related complexes have been obtained under these conditions, in which one of the azide insertion compounds reductively eliminates to give an allylic functionalization product stoichiometrically. 3.1 reacts with various primary alcohols to give the decarbonylation dihydride complex ToMRh(H)2CO (4.1). 4.1 shows catalytic reactivity for primary alcohol decarbonylation under a photolytic condition. Meanwhile, 2.2 has been found to be more reactive than 4.1 for catalytic alcohol decarbonylation under the same condition. Various complexes and primary

  2. Amine-intercalated α-zirconium phosphates as lubricant additives

    International Nuclear Information System (INIS)

    In this study, three types of amines intercalated α-zirconium phosphate nanosheets with different interspaces were synthesized and examined as lubricant additives to a mineral oil. Results from tribological experiments illustrated that these additives improved lubricating performance. Results of rheological experiments showed that the viscosity of the mineral oil was effectively reduced with the addition of α-zirconium phosphate nanosheets. The two-dimensional structure, with larger interspaces, resulting from amine intercalation, exhibited improved effectiveness in reducing viscosity. This study demonstrates that the nanosheet structure of α-zirconium phosphates is effective in friction reduction. The manufacture of lubricants with tailored viscosity is possible by using different intercalators

  3. Lithium intercalation in LiW3O9F

    International Nuclear Information System (INIS)

    Lithium has been intercalated in LiW3O9F. This phase exhibits a peculiar packing of hexagonal tungsten bronze layers. Up to two lithium atoms can be intercalated reversibly. If the Li3W3O9F composition is overpassed the reaction becomes irreversible and an amorphization occurs. The variation of the diffusion coefficient versus the amount of lithium has been determined from the electrochemical relaxation curves. An NMR study has shown that Li+ ions are not mobile in LiW3O9F and have a high mobility in intercalated materials at room temperature. (author). 6 refs.; 5 figs

  4. Dissecting the Dynamic Pathways of Stereoselective DNA Threading Intercalation.

    Science.gov (United States)

    Almaqwashi, Ali A; Andersson, Johanna; Lincoln, Per; Rouzina, Ioulia; Westerlund, Fredrik; Williams, Mark C

    2016-03-29

    DNA intercalators that have high affinity and slow kinetics are developed for potential DNA-targeted therapeutics. Although many natural intercalators contain multiple chiral subunits, only intercalators with a single chiral unit have been quantitatively probed. Dumbbell-shaped DNA threading intercalators represent the next order of structural complexity relative to simple intercalators, and can provide significant insights into the stereoselectivity of DNA-ligand intercalation. We investigated DNA threading intercalation by binuclear ruthenium complex [μ-dppzip(phen)4Ru2](4+) (Piz). Four Piz stereoisomers are defined by the chirality of the intercalating subunit (Ru(phen)2dppz) and the distal subunit (Ru(phen)2ip), respectively, each of which can be either right-handed (Δ) or left-handed (Λ). We used optical tweezers to measure single DNA molecule elongation due to threading intercalation, revealing force-dependent DNA intercalation rates and equilibrium dissociation constants. The force spectroscopy analysis provided the zero-force DNA binding affinity, the equilibrium DNA-ligand elongation Δxeq, and the dynamic DNA structural deformations during ligand association xon and dissociation xoff. We found that Piz stereoisomers exhibit over 20-fold differences in DNA binding affinity, from a Kd of 27 ± 3 nM for (Δ,Λ)-Piz to a Kd of 622 ± 55 nM for (Λ,Δ)-Piz. The striking affinity decrease is correlated with increasing Δxeq from 0.30 ± 0.02 to 0.48 ± 0.02 nm and xon from 0.25 ± 0.01 to 0.46 ± 0.02 nm, but limited xoff changes. Notably, the affinity and threading kinetics is 10-fold enhanced for right-handed intercalating subunits, and 2- to 5-fold enhanced for left-handed distal subunits. These findings demonstrate sterically dispersed transition pathways and robust DNA structural recognition of chiral intercalators, which are critical for optimizing DNA binding affinity and kinetics. PMID:27028636

  5. Electrochemical Intercalation of Sodium into Silicon Thin Film

    Institute of Scientific and Technical Information of China (English)

    Dong-Yeon Kim; Hyo-Jun Ahn; Gyu-Bong Cho; Jong-Seon Kim; Ho-Suk Ryu; Ki-Won Kim; Jou-Hyeon Ahn; Won-Cheol Shin

    2008-01-01

    In order to investigate the possibility of Si thin film as an anode for Na battery, we studied the electrochemical intercalation of sodium into the Si film. Amorphous Si thin film electrode was prepared using DC magnetron sputtering. Sodium ion could intercalate into Si thin film upto Na0.52Si, i.e. 530mAh · g-1-Si. The first discharge capacity was 80mAh.·g-1-Si, which meant reversible amount of sodium intercalation. The discharge capacity slightly decreased to 70mAh · g-1-Si after 10 cycles.

  6. Effects of graphene defects on Co cluster nucleation and intercalation

    International Nuclear Information System (INIS)

    Four kinds of defects are observed in graphene grown on Ru (0001) surfaces. After cobalt deposition at room temperature, the cobalt nanoclusters are preferentially located at the defect position. By annealing at 530°C, cobalt atoms intercalate at the interface of Graphene/Ru (0001) through the defects. Further deposition and annealing increase the sizes of intercalated Co islands. This provides a method of controlling the arrangement of cobalt nanoclusters and also the density and the sizes of intercalated cobalt islands, which would find potential applications in catalysis industries, magnetism storage, and magnetism control in future information technology. (interdisciplinary physics and related areas of science and technology)

  7. Hydroformylation of methyl oleate catalyzed by rhodium complexes; Hidroformilacao do oleato de metila catalisada por complexos de rodio

    Energy Technology Data Exchange (ETDEWEB)

    Mendes, Ana Nery Furlan [Universidade Federal do Espirito Santo (UFES), Sao Mateus, ES (Brazil). Centro Universitario Norte do Espirito Santo. Dept. de Ciencias Naturais; Rosa, Ricardo Gomes da; Gregorio, Jose Ribeiro, E-mail: jrg@iq.ufrgs.br [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Inst. de Quimica

    2012-07-01

    In this work, we describe the hydroformylation of methyl oleate catalyzed by several rhodium complexes. Parameters including total pressure, phosphorous/rhodium and CO/H{sub 2} ratio, temperature and phosphorous ligands were scanned. Total conversion of the starting double bonds was achieved while maintaining excellent selectivity in aldehydes. (author)

  8. Dosimetric study in ocular brachytherapy with iodine 125 and ruthenium/rhodium-106

    International Nuclear Information System (INIS)

    To analyze dose distribution utilizing plaques with iodine-125 and ruthenium/rhodium-106 in a computational model of the ocular region. A voxel-based computational model including the different tissues of the ocular region was utilized with the plaque positioned on the sclera. The Monte Carlo code was utilized for simulating irradiation. The dose distribution is demonstrated by isodoses curves. Computational simulations demonstrate the dose distribution inside the ocular bulb as well as in adjacent outside structures. The results have allowed the authors to compare the spatial distribution of doses generated by beta particles and photons. The simulations demonstrated that the utilization of iodine-125 seeds implies a high dose to the crystalline lens, while ruthenium/rhodium-106 results in high dose on the sclera surface. The dose to the crystalline lens depends on the tumor position and thickness, the plaque diameter, and the radionuclide utilized. In the present study, the ruthenium/rhodium-106 source is recommended for low tumor thickness. Irradiation with iodine-125 results in higher doses to the crystalline lens than irradiation with ruthenium/rhodium-106. The maximum value for dose to the crystalline lens corresponds to 12.75% of the maximum dose with iodine-125 and only 0.005% for ruthenium/rhodium-106. (author)

  9. Strain Lattice Imprinting in Graphene by C60 Intercalation at the Graphene/Cu Interface

    NARCIS (Netherlands)

    Monazami, Ehsan; Bignardi, Luca; Rudolf, Petra; Reinke, Petra

    2015-01-01

    Intercalation of C60 molecules at the graphene-substrate interface by annealing leads to amorphous and crystalline intercalated structures. A comparison of topography and electronic structure with wrinkles and moiré patterns confirms intercalation. The intercalated molecules imprint a local strain/d

  10. Branching Out: Rhodium-Catalyzed Allylation with Alkynes and Allenes.

    Science.gov (United States)

    Koschker, Philipp; Breit, Bernhard

    2016-08-16

    We present a new and efficient strategy for the atom-economic transformation of both alkynes and allenes to allylic functionalized structures via a Rh-catalyzed isomerization/addition reaction which has been developed in our working group. Our methodology thus grants access to an important structural class valued in modern organic chemistry for both its versatility for further functionalization and the potential for asymmetric synthesis with the construction of a new stereogenic center. This new methodology, inspired by mechanistic investigations by Werner in the late 1980s and based on preliminary work by Yamamoto and Trost, offers an attractive alternative to other established methods for allylic functionalization such as allylic substitution or allylic oxidation. The main advantage of our methodology consists of the inherent atom economy in comparison to allylic oxidation or substitution, which both produce stoichiometric amounts of waste and, in case of the substitution reaction, require prefunctionalization of the starting material. Starting out with the discovery of a highly branched-selective coupling reaction of carboxylic acids with terminal alkynes using a Rh(I)/DPEphos complex as the catalyst system, over the past 5 years we were able to continuously expand upon this chemistry, introducing various (pro)nucleophiles for the selective C-O, C-S, C-N, and C-C functionalization of both alkynes and the double-bond isomeric allenes by choosing the appropriate rhodium/bidentate phosphine catalyst. Thus, valuable compounds such as branched allylic ethers, sulfones, amines, or γ,δ-unsaturated ketones were successfully synthesized in high yields and with a broad substrate scope. Beyond the branched selectivity inherent to rhodium, many of the presented methodologies display additional degrees of selectivity in regard to regio-, diastereo-, and enantioselective transformations, with one example even proceeding via a dynamic kinetic resolution. Many advances

  11. Electronic spectra of anions intercalated in layered double hydroxides

    Indian Academy of Sciences (India)

    S Radha; P Vishnu Kamath

    2013-10-01

    Transition metal complexes intercalated in layered double hydroxides have a different electronic structure as compared to their free state owing to their confinement within the interlayer gallery. UV–Vis absorptions of the intercalated complex anions show a significant shift as compared to their free state. The ligand to metal charge transfer transitions of the ferricyanide anion show a red shift on intercalation. The ferrocyanide ion shows a significant blue shift of – bands due to the increased separation between 2g and g levels on intercalation. MnO$^{-}_{4}$ ion shows a blue shift in its ligand to metal charge transfer transition since the non-bonding 1 level of oxygen from which the transition arises is stabilized.

  12. Intercalation of Carbon Nanotube Fibers to Improve their Conductivity Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposed research will explore how NASA intercalation technology can be used to lower the resistivity of the new Rice-Teijin fiber make them viable for NASA...

  13. Monodisperse Platinum and Rhodium Nanoparticles as Model Heterogeneous Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Grass, Michael Edward [Univ. of California, Berkeley, CA (United States)

    2008-09-01

    Model heterogeneous catalysts have been synthesized and studied to better understand how the surface structure of noble metal nanoparticles affects catalytic performance. In this project, monodisperse rhodium and platinum nanoparticles of controlled size and shape have been synthesized by solution phase polyol reduction, stabilized by polyvinylpyrrolidone (PVP). Model catalysts have been developed using these nanoparticles by two methods: synthesis of mesoporous silica (SBA-15) in the presence of nanoparticles (nanoparticle encapsulation, NE) to form a composite of metal nanoparticles supported on SBA-15 and by deposition of the particles onto a silicon wafer using Langmuir-Blodgett (LB) monolayer deposition. The particle shapes were analyzed by transmission electron microscopy (TEM) and high resolution TEM (HRTEM) and the sizes were determined by TEM, X-ray diffraction (XRD), and in the case of NE samples, room temperature H2 and CO adsorption isotherms. Catalytic studies were carried out in homebuilt gas-phase reactors. For the nanoparticles supported on SBA-15, the catalysts are in powder form and were studied using the homebuilt systems as plug-flow reactors. In the case of nanoparticles deposited on silicon wafers, the same systems were operated as batch reactors. This dissertation has focused on the synthesis, characterization, and reaction studies of model noble metal heterogeneous catalysts. Careful control of particle size and shape has been accomplished though solution phase synthesis of Pt and Rh nanoparticles in order to elucidate further structure-reactivity relationships in noble metal catalysis.

  14. Complex nitrates of rhodium(III) in aqueous solutions

    International Nuclear Information System (INIS)

    Concentrated solutions of sodium hexanitrorhodate(III) have been studied by 103Rh, 17O, 14N, and 35Cl NMR, as well as electronic and IR spectroscopy. It has been established that in solutions not containing acids the coordinated nitro groups undergo very slow replacement with the formation of mononuclear aquo acids and polynuclear species containing bridging hydroxo ligands. In acidic media the hexanitrorhodate(III) ions are rapidly converted into complex species containing three nitro groups, among which trinitrotriaquorhodium(III) has the greatest stability. The replacement of the three remaining nitro groups takes place slowly and results in the formation of chloroaquonitro compounds. The absence of additivity of the 103Rh chemical shifts in systems of nitro compounds of rhodium(III) has been established. The interaction of sodium hexanitrorhodate(III) with hydrochloric acid results in the formation of complex species containing coordinated water in all stages of the reaction. The processes taking place are not confined to substitution reactions, since they are accompanied by redox conversions. The mechanisms of these reactions have been discussed

  15. Thermal effects on Rhodium nanoparticles supported on carbon

    International Nuclear Information System (INIS)

    EXAFS measurements have been made in the temperature range 5 – 300 K on rhodium nano-clusters of average diameters 15.9 and 11.5 Å (rms dispersion 7.2 and 4.7 Å, respectively) supported on carbon, as well as on a Rh reference foil. The preliminary results of the first shell analysis are presented. The Debye temperature is slightly smaller in n-Rh with respect to bulk and decreases when the cluster size decreases. The results of amplitude analysis (coordination number and static DW) are sensitive to the inclusion of the 4th cumulant. In going from bulk Rh to n-Rh and decreasing the nanocluster size the average coordination number decreases and the static disorder increases. A contraction of the average nearest-neighbour distance is observed at 5 K, −0.004 Å and −0.009 Å for the larger and smaller clusters, respectively, accompanied by a very slight thermal expansion.

  16. In situ dynamic study of hydrogen oxidation on rhodium.

    Science.gov (United States)

    Visart de Bacarmé, T; Bär, T; Kruse, N

    2001-10-01

    The reaction of hydrogen/oxygen gas mixtures with rhodium single crystals was studied using video-FIM (Field Ion Microscopy) at temperatures between 350 and 550 K and up to 2 x 10(-2) Pa total pressure. Imaging at 500 K in a hydrogen rich gas mixture (H2:O2 = 9) revealed considerable morphological changes of the (0 0 1)-oriented field emitter tip, i.e. the growth of low-index at the expense of high-index planes and strong crystal coarsening. Decreasing the hydrogen partial pressure led to chemical and structural changes of the Rh sample. Starting on the [1 1 0] planes a surface oxide formed, which spread anisotropically across the surface until it finally covered the whole visible surface area. The transformation was reversible upon increasing the hydrogen pressure back to its initial value. However, a hysteresis behavior was observed, i.e. a larger hydrogen partial pressure was found to be necessary to re-establish the initial patterns of a reactive Oad/Had layer. By varying the temperature from 400 to 500 K a phase diagram was established for the Oad/Had system. Increasing the electric field proved to shift the phase diagram towards higher H2 pressures. At 550K self-sustained kinetic oscillations with a cycle time of approximately 40s could be observed. PMID:11770755

  17. Microstructure and oxidation behaviour investigation of rhodium modified aluminide coating deposited on CMSX 4 superalloy.

    Science.gov (United States)

    Zagula-Yavorska, Maryana; Morgiel, Jerzy; Romanowska, Jolanta; Sieniawski, Jan

    2016-03-01

    The CMSX 4 superalloy was coated with rhodium 0.5-μm thick layer and next aluminized by the CVD method. The coating consisted of two layers: the additive and the interdiffusion one. The outward diffusion of nickel from the substrate turned out to be a coating growth dominating factor. The additive layer consists of the β-NiAl phase, whereas the interdiffusion layer consists of the β-NiAl phase with precipitates of σ and μ phases. Rhodium has dissolved in the coating up to the same level in the matrix and in the precipitates. The oxidation test proved that the rhodium modified aluminide coating showed about twice better oxidation resistance than the nonmodified one. PMID:26892917

  18. A molecular model for proflavine-DNA intercalation.

    OpenAIRE

    Neidle, S; Pearl, L H; Herzyk, P; Berman, H M

    1988-01-01

    A molecular model has been derived for the intercalation of proflavine into the CpG site of the decamer duplex of d(GATACGATAC). The starting geometry of the intercalation site was taken from previous crystallographic studies on the d(CpG)-proflavine complex, and molecular mechanics used to obtain a stereochemically acceptable structure. This has widened grooves compared to standard A- or B- double helices, as well as distinct conformational, roll, twist and tilt features.

  19. Effect of Diffusion on Lithium Intercalation in Titanium Dioxide

    Science.gov (United States)

    Koudriachova, Marina V.; Harrison, Nicholas M.; de Leeuw, Simon W.

    2001-02-01

    A new model of Li intercalation into rutile and anatase structured titania has been developed from first principles calculations. The model includes both thermodynamic and kinetic effects and explains the observed differences in intercalation behavior and their temperature dependence. The important role of strong local deformations of the lattice and elastic screening of interlithium interactions is demonstrated. In addition, a new phase of LiTiO2 is reported.

  20. Electronic Band Engineering of Epitaxial Graphene by Atomic Intercalation

    Science.gov (United States)

    Jayasekera, Thushari; Sandin, Andreas; Xu, Shu; Wheeler, Virginia; Gaskill, D. K.; Rowe, J. E.; Kim, K. W.; Dougherty, Daniel B.; Buongiorno Nardelli, M.

    2012-02-01

    Using calculations from first principles, we have investigated possible ways of engineering the electronic band structure of epitaxial graphene on SiC. In particular, intercalation of different atomic species, such as Hydrogen, Fluorine, Sodium, Germanium, Carbon and Silicon is shown to modify and tune the interface electronic properties and band alignments. Our results suggest that intercalation in graphene is quite different from that in graphite, and could provide a fundamentally new way to achieve electronic control in graphene electronics.

  1. Thermodynamics of Lithium Intercalation into Graphites and Disordered Carbons

    OpenAIRE

    Reynier, Y. F.; Yazami, R.; Fultz, B.

    2004-01-01

    The temperature dependence of the open-circuit potential of lithium half-cells was measured for electrodes of carbon materials having different amounts of structural disorder. The entropy of lithium intercalation, DeltaS, and enthalpy of intercalation, DeltaH, were determined over a broad range of lithium concentrations. For the disordered carbons, DeltaS is small. For graphite, an initially large DeltaS decreases with lithium concentration, becomes negative, and then shows two plateaus assoc...

  2. Graphene on Mica - Intercalated Water Trapped for Life

    OpenAIRE

    Ochedowski, O.; B. Kleine Bussmann; Schleberger, M.

    2014-01-01

    In this work we study the effect of thermal processing of exfoliated graphene on mica with respect to changes in graphene morphology and surface potential. Mild annealing to temperatures of about 200°C leads to the removal of small amounts of intercalated water at graphene edges. By heating to 600°C the areas without intercalated water are substantially increased enabling a quantification of the charge transfer properties of the water layer by locally resolved Kelvin probe force microscopy da...

  3. Intercalation mechanisms of lithium into graphitized needle cokes

    Institute of Scientific and Technical Information of China (English)

    苏玉长; 尹志民; 徐仲榆

    2001-01-01

    A needle coke was graphitized at different heat treatment temperature (2000℃ to 3000℃). The electrochemical intercalation mechanism of Li into the graphitized coke has been studied in Li|1mol*L-1 LiClO4+ethylene carbonate/diethylene carbonate|graphite cells, using an in-situ X-Ray diffraction (XRD) technique. The study of Li-C intercalation processes of the graphitized coke reveals that there are three major types of intercalation behavior. The first is uniformly intercalated at all Li-C compounds in graphitized coke heated at 2250℃; the second is obviously staging phenomenon during intercalating for the graphitized coke heated at 2750℃; the third is cointercalation of solvated Li-ion at high potential (>0.3V) and then lithium electrochemical intercalation at lower potential for that heated at 3000℃, resulting in the decrease of capacity and efficiency of graphite negative electrode for lithium-ion secondary battery.

  4. Genotoxicity of non-covalent interactions: DNA intercalators

    International Nuclear Information System (INIS)

    This review provides an update on the mutagenicity of intercalating chemicals, as carried out over the last 17 years. The most extensively studied DNA intercalating agents are acridine and its derivatives, that bind reversibly but non-covalently to DNA. These are frameshift mutagens, especially in bacteria and bacteriophage, but do not otherwise show a wide range of mutagenic properties. Di-acridines or di-quinolines may be either mono- or bis-intercalators, depending upon the length of the alkyl chain separating the chromophores. Those which monointercalate appear as either weak frameshift mutagens in bacteria, or as non-mutagens. However, some of the bisintercalators act as 'petite' mutagens in Saccharomyces cerevisiae, suggesting that they may be more likely to target mitochondrial as compared with nuclear DNA. Some of the new methodologies for detecting intercalation suggest this may be a property of a wider range of chemicals than previously recognised. For example, quite a number of flavonoids appear to intercalate into DNA. However, their mutagenic properties may be dominated by the fact that many of them are also able to inhibit topoisomerase II enzymes, and this property implies that they will be potent recombinogens and clastogens. DNA intercalation may serve to position other, chemically reactive molecules, in specific ways on the DNA, leading to a distinctive (and wider) range of mutagenic properties, and possible carcinogenic potential

  5. Improvement on stability of square planar rhodium (Ⅰ) complexes for carbonylation of methanol to acetic acid

    Institute of Scientific and Technical Information of China (English)

    蒋华; 潘平来; 袁国卿; 陈新滋

    1999-01-01

    A series of square planar cis-dicarbonyl polymer coordinated rhodium complexes with uncoordinated donors near the central rhodium atoms for carbonylation of methanol to acetic acid are reported. Data of IR, XPS and thermal analysis show that these complexes are very stable. The intramolecular substitution reaction is proposed for their high stability. These complexes show excellent catalytic activity, selectivity and less erosion to the equipment for the methanol carbonylation to acetic acid. The distillation process may be used instead of flash vaporization in the manufacture of acetic acid, which reduces the investment on the equipment.

  6. Rhodium-catalyzed C-C coupling reactions via double C-H activation.

    Science.gov (United States)

    Li, Shuai-Shuai; Qin, Liu; Dong, Lin

    2016-05-18

    Various rhodium-catalyzed double C-H activations are reviewed. These powerful strategies have been developed to construct C-C bonds, which might be widely embedded in complex aza-fused heterocycles, polycyclic skeletons and heterocyclic scaffolds. In particular, rhodium(iii) catalysis shows good selectivity and reactivity to functionalize the C-H bond, generating reactive organometallic intermediates in most of the coupling reactions. Generally, intermolecular, intramolecular and multi-component coupling reactions via double C-H activations with or without heteroatom-assisted chelation are discussed in this review. PMID:27099126

  7. 13 C and 31 P NMR use in phosphinite synthesis and rhodium cationic catalysts accompaniment

    International Nuclear Information System (INIS)

    Several studies on rigid cyclic frameworks have been developed recently. This work shows the use of 13 C and 31 P NMR analysis for identifying and characterizing the molecular structures of phosphinites, thiophosphinites and rhodium catalysts. The phosphinites were synthesized and rhodium complexes prepared from them, aiming the catalysts synthesis for hydrogenation processes. Synthesizing phosphinites and thiophosphinites, alcohols on their racemic form were used, therefore, the catalysts were obtained as diasteroisomers. 13 C and 31 P NMR data are discussed in details and chemical shifts are also analysed

  8. Discriminating Intercalative Effects of Threading Intercalator Nogalamycin, from Classical Intercalator Daunomycin, Using Single Molecule Atomic Force Spectroscopy.

    Science.gov (United States)

    Banerjee, T; Banerjee, S; Sett, S; Ghosh, S; Rakshit, T; Mukhopadhyay, R

    2016-01-01

    DNA threading intercalators are a unique class of intercalating agents, albeit little biophysical information is available on their intercalative actions. Herein, the intercalative effects of nogalamycin, which is a naturally-occurring DNA threading intercalator, have been investigated by high-resolution atomic force microscopy (AFM) and spectroscopy (AFS). The results have been compared with those of the well-known chemotherapeutic drug daunomycin, which is a non-threading classical intercalator bearing structural similarity to nogalamycin. A comparative AFM assessment revealed a greater increase in DNA contour length over the entire incubation period of 48 h for nogalamycin treatment, whereas the contour length increase manifested faster in case of daunomycin. The elastic response of single DNA molecules to an externally applied force was investigated by the single molecule AFS approach. Characteristic mechanical fingerprints in the overstretching behaviour clearly distinguished the nogalamycin/daunomycin-treated dsDNA from untreated dsDNA-the former appearing less elastic than the latter, and the nogalamycin-treated DNA distinguished from the daunomycin-treated DNA-the classically intercalated dsDNA appearing the least elastic. A single molecule AFS-based discrimination of threading intercalation from the classical type is being reported for the first time. PMID:27183010

  9. Single-Component Conductors: A Sturdy Electronic Structure Generated by Bulky Substituents.

    Science.gov (United States)

    Filatre-Furcate, Agathe; Bellec, Nathalie; Jeannin, Olivier; Auban-Senzier, Pascale; Fourmigué, Marc; Íñiguez, Jorge; Canadell, Enric; Brière, Benjamin; Ta Phuoc, Vinh; Lorcy, Dominique

    2016-06-20

    While the introduction of large, bulky substituents such as tert-butyl, -SiMe3, or -Si(isopropyl)3 has been used recently to control the solid state structures and charge mobility of organic semiconductors, this crystal engineering strategy is usually avoided in molecular metals where a maximized overlap is sought. In order to investigate such steric effects in single component conductors, the ethyl group of the known [Au(Et-thiazdt)2] radical complex has been replaced by an isopropyl one to give a novel single component molecular conductor denoted [Au(iPr-thiazdt)2] (iPr-thiazdt: N-isopropyl-1,3-thiazoline-2-thione-4,5-dithiolate). It exhibits a very original stacked structure of crisscross molecules interacting laterally to give a truly three-dimensional network. This system is weakly conducting at ambient pressure (5 S·cm(-1)), and both transport and optical measurements evidence a slowly decreasing energy gap under applied pressure with a regime change around 1.5 GPa. In contrast with other conducting systems amenable to a metallic state under physical or chemical pressure, the Mott insulating state is stable here up to 4 GPa, a consequence of its peculiar electronic structure. PMID:27266960

  10. Synthesis and Antiplasmodial Activity of Novel Chloroquine Analogues with Bulky Basic Side Chains.

    Science.gov (United States)

    Tasso, Bruno; Novelli, Federica; Tonelli, Michele; Barteselli, Anna; Basilico, Nicoletta; Parapini, Silvia; Taramelli, Donatella; Sparatore, Anna; Sparatore, Fabio

    2015-09-01

    Chloroquine is commonly used in the treatment and prevention of malaria, but Plasmodium falciparum, the main species responsible for malaria-related deaths, has developed resistance against this drug. Twenty-seven novel chloroquine (CQ) analogues characterized by a side chain terminated with a bulky basic head group, i.e., octahydro-2H-quinolizine and 1,2,3,4,5,6-hexahydro-1,5-methano-8H-pyrido[1,2-a][1,5]diazocin-8-one, were synthesized and tested for activity against D-10 (CQ-susceptible) and W-2 (CQ-resistant) strains of P. falciparum. Most compounds were found to be active against both strains with nanomolar or sub-micromolar IC50 values. Eleven compounds were found to be 2.7- to 13.4-fold more potent than CQ against the W-2 strain; among them, four cytisine derivatives appear to be of particular interest, as they combine high potency with low cytotoxicity against two human cell lines (HMEC-1 and HepG2) along with easier synthetic accessibility. Replacement of the 4-NH group with a sulfur bridge maintained antiplasmodial activity at a lower level, but produced an improvement in the resistance factor. These compounds warrant further investigation as potential drugs for use in the fight against malaria. PMID:26213237

  11. Intercalation of metals and silicon at the interface of epitaxial graphene and its substrates

    International Nuclear Information System (INIS)

    Intercalations of metals and silicon between epitaxial graphene and its substrates are reviewed. For metal intercalation, seven different metals have been successfully intercalated at the interface of graphene/Ru(0001) and form different intercalated structures. Meanwhile, graphene maintains its original high quality after the intercalation and shows features of weakened interaction with the substrate. For silicon intercalation, two systems, graphene on Ru(0001) and on Ir(111), have been investigated. In both cases, graphene preserves its high quality and regains its original superlative properties after the silicon intercalation. More importantly, we demonstrate that thicker silicon layers can be intercalated at the interface, which allows the atomic control of the distance between graphene and the metal substrates. These results show the great potential of the intercalation method as a non-damaging approach to decouple epitaxial graphene from its substrates and even form a dielectric layer for future electronic applications. (topical review - low-dimensional nanostructures and devices)

  12. Electrochemical study of {beta}-diketonatobis(triphenylphosphite)rhodium(I) complexes

    Energy Technology Data Exchange (ETDEWEB)

    Erasmus, Johannes J.C. [Department of Chemistry, PO Box 339, University of the Free State, Bloemfontein 9300 (South Africa); Conradie, Jeanet, E-mail: conradj@ufs.ac.z [Department of Chemistry, PO Box 339, University of the Free State, Bloemfontein 9300 (South Africa)

    2011-10-30

    Highlights: > Rh(I) is electrochemically irreversible oxidized to Rh(III) in [Rh(RCOCHCOR')(P(OPh){sub 3}){sub 2}]. > Oxidation potentials E{sub pa}(Rh) and kinetic oxidative addition rate constants relate linearly. > Hammett {sigma} values, group electronegativities and the Lever ligand parameter relate to E{sub pa}(Rh). - Abstract: The electrochemical behaviour of the series of ten [Rh(RCOCHCOR')(P(OPh){sub 3}){sub 2}] complexes with R, R' = CF{sub 3}, CF{sub 3} (1), CF{sub 3}, CH{sub 3} (2), CF{sub 3}, Ph (C{sub 6}H{sub 5}) (3), CF{sub 3}, Fc (ferrocenyl = (C{sub 5}H{sub 5})Fe(C{sub 5}H{sub 4})) (4), CH{sub 3}, Ph (5), CH{sub 3}, CH{sub 3} (6), Ph, Ph (7), Fc, CH{sub 3} (8), Fc, Ph (9) and Fc, Fc (10) were studied in acetonitrile containing 0.100 mol dm{sup -3} tetra-n-butylammonium hexafluorophosphate as supporting electrolyte utilizing a glassy carbon working electrode. Results are consistent with Rh(I) being first oxidized in an electrochemically irreversible two-electron transfer process at peak anodic potentials ranging E{sub pa}(Rh) = 0.124-0.881 V vs. Fc/Fc{sup +}. For the ferrocene-containing complexes (4), and (8)-(10) the rhodium oxidation was followed by the electrochemically reversible oxidation of the ferrocenyl group in a one-electron transfer process at a slightly more positive potential. Relationships were established between the electrochemical quantity E{sub pa}(Rh) and kinetic parameter log k{sub 2} as well the sum of experimental group electronegativities (Gordy Scale) of the R and R' groups ({chi}{sub R} + {chi}{sub R'}), the Hammett {sigma} values ({sigma}{sub R} + {sigma}{sub R'}) and the Lever ligand parameter E{sub L} for the [Rh(RCOCHCOR')(P(OPh){sub 3}){sub 2}] complexes: E{sub pa}(Rh) (vs. Fc/Fc{sup +}/V) = 0.31 ({chi}{sub R} + {chi}{sub R'})-1.09 = 0.56 ({sigma}{sub R} + {sigma}{sub R'}) + 0.28 = S{sub M} ({Sigma}E{sub L}) + (I{sub M} - 0.66 V) = -0.23 log k{sub 2} - 0.03 (k{sub 2

  13. Olefins hydro-formylation catalysed by rhodium complexes using ionic liquids; Hydroformylation des olefines par les complexes du rhodium dans les liquides ioniques

    Energy Technology Data Exchange (ETDEWEB)

    Favre, F.

    2000-10-26

    Biphasic long chain olefins hydro-formylation catalysed by rhodium complexes using ionic liquids allows a selective reaction and an easy separation of the products from the catalyst. This study reports the synthesis of ionic liquids that were used as the catalyst's solvent. Their physical and chemical properties (melting point, solubility of organic substrates) can be varied with the structure of the organic cation (imidazolium, pyridinium, pyrrolydinium) and with its substituents (nature, length, number). It depends also on the nature of the inorganic anion (hexa-fluoro-phosphate, tetrafluoroborate, tri-fluoro-acetate, triflate, bistriflylamidure...). The use of phosphorus ligands bearing ionic functions proved to be efficient to maintain the onerous rhodium catalyst in the ionic liquid phase. Phosphines, phosphites and phosphinites including anionic (sulfonate, carboxylate) or cationic (imidazolium, pyridinium, guanidinium, phosphonium) groups have been synthesised. Finally, the influences of the ligand and of the ionic liquid on the catalytic system performances are described. Selectivities in aldehydes and reaction rates proved to be highly dependent on the nature of the ligand and of the ionic liquid. The different possibilities of recycling the ionic phase containing the rhodium catalyst have been also studied. (author)

  14. Determination of phenolic compounds using spectral and color transitions of rhodium nanoparticles.

    Science.gov (United States)

    Gatselou, Vasiliki; Christodouleas, Dionysios C; Kouloumpis, Antonios; Gournis, Dimitrios; Giokas, Dimosthenis L

    2016-08-17

    This work reports a new approach for the determination of phenolic compounds based on their interaction with citrate-capped rhodium nanoparticles. Phenolic compounds (i.e., catechins, gallates, cinnamates, and dihydroxybenzoic acids) were found to cause changes in the size and localized surface plasmon resonance of rhodium nanoparticles, and therefore, give rise to analyte-specific spectral and color transitions in the rhodium nanoparticle suspensions. Upon reaction with phenolic compounds (mainly dithydroxybenzoate derivatives, and trihydroxybenzoate derivatives), new absorbance peaks at 350 nm and 450 nm were observed. Upon reaction with trihydroxybenzoate derivatives, however, an additional absorbance peak at 580 nm was observed facilitating the speciation of phenolic compounds in the sample. Both absorbance peaks at 450 nm and 580 nm increased with increasing concentration of phenolic compounds over a linear range of 0-500 μM. Detection limits at the mid-micromolar levels were achieved, depending on the phenolic compound involved, and with satisfactory reproducibility (phenolic content and total catechin content were developed and applied in tea samples. The obtained results correlated favorably with commonly used methods (i.e., Folin-Ciocalteu and aluminum complexation assay). Not the least, the finding that rhodium nanoparticles can react with analytes and exhibit unique localized surface plasmon resonance bands in the visible region, can open new opportunities for developing new optical and sensing analytical applications. PMID:27286772

  15. The Role of the Element Rhodium in the Hyperbolic Law of the Periodic Table of Elements

    OpenAIRE

    Albert Khazan

    2008-01-01

    The role of the element rhodium as an independent affirmation of calculations by the Hyperbolic Law and validity of all its relations is shown herein. The deviation in calculation by this method of the atomic mass of heaviest element is 0.0024%, and its coefficient of scaling 0.001-0.005%.

  16. Double-spin-flip resonance of rhodium nuclei at positive and negative spin temperatures

    DEFF Research Database (Denmark)

    Tuoriniemi, J.T.; Knuuttila, T.A.; Lefmann, K.;

    2000-01-01

    Sensitive SQUID-NMR measurements were used to study the mutual interactions in the highly polarized nuclear-spin system of rhodium metal. The dipolar coupling gives rise to a weak double-spin-flip resonance. The observed frequency shifts allow deducing separately the dipolarlike contribution...

  17. The Role of the Element Rhodium in the Hyperbolic Law of the Periodic Table of Elements

    Directory of Open Access Journals (Sweden)

    Albert Khazan

    2008-07-01

    Full Text Available The role of the element rhodium as an independent affirmation of calculations by the Hyperbolic Law and validity of all its relations is shown herein. The deviation in calculation by this method of the atomic mass of heaviest element is 0.0024%, and its coefficient of scaling 0.001-0.005%.

  18. Double-spin-flip resonance of rhodium nuclei at positive and negative spin temperatures

    DEFF Research Database (Denmark)

    Tuoriniemi, J.T.; Knuuttila, T.A.; Lefmann, K.; Nummila, K.K.; Yao, W.; Rasmussen, F.B.

    2000-01-01

    Sensitive SQUID-NMR measurements were used to study the mutual interactions in the highly polarized nuclear-spin system of rhodium metal. The dipolar coupling gives rise to a weak double-spin-flip resonance. The observed frequency shifts allow deducing separately the dipolarlike contribution and...

  19. Azido[1,1'-bis(diphenylphosphino)ferrocene](pentamethylcyclopentadienyl)rhodium(III) hexafluorophosphate.

    Science.gov (United States)

    Han, Won Seok; Lee, Soon W

    2004-04-01

    In the title compound, azido-2kappaN-bis[micro-(1eta(5):2kappaP)-diphenylphosphinocyclopentadienyl][2(eta(5))-pentamethylcyclopentadienyl]iron(III)rhodium(III) hexafluorophosphate, [[Rh(C(10)H(15))(N(3))][Fe(micro-C(17)H(14)P)(2)

  20. Rhodium dihydride (RhH2) with high volumetric hydrogen density

    Science.gov (United States)

    Li, Bing; Ding, Yang; Kim, Duck Young; Ahuja, Rajeev; Zou, Guangtian; Mao, Ho-Kwang

    2011-01-01

    Materials with very high hydrogen density have attracted considerable interest due to a range of motivations, including the search for chemically precompressed metallic hydrogen and hydrogen storage applications. Using high-pressure synchrotron X-ray diffraction technique and theoretical calculations, we have discovered a new rhodium dihydride (RhH2) with high volumetric hydrogen density (163.7 g/L). Compressing rhodium in fluid hydrogen at ambient temperature, the fcc rhodium metal absorbs hydrogen and expands unit-cell volume by two discrete steps to form NaCl-typed fcc rhodium monohydride at 4 GPa and fluorite-typed fcc RhH2 at 8 GPa. RhH2 is the first dihydride discovered in the platinum group metals under high pressure. Our low-temperature experiments show that RhH2 is recoverable after releasing pressure cryogenically to 1 bar and is capable of retaining hydrogen up to 150 K for minutes and 77 K for an indefinite length of time. PMID:22039219

  1. Erzeugung von Wasserstoff mittels katalytischer Partialoxidation höherer Kohlenwasserstoffe an Rhodium

    OpenAIRE

    Hartmann, Marco

    2009-01-01

    Diese Arbeit befasst sich mit der Untersuchung der katalytischen Partialoxidation (CPOX) höherer Kohlenwasserstoffe an mit Rhodium beschichteten Wabenkörpern. Die Reaktion ermöglicht die autotherme Generierung von Wasserstoff aus Kraftstoffen wie Benzin und Diesel zur Versorgung von Brennstoffzellen aus bestehenden Versorgungsnetzen.

  2. Application of carbon-13 and phosphorous-31 NMR to follow phosphinites and rhodium catalysts synthesis

    International Nuclear Information System (INIS)

    Phosphinites and thiophosphites derived from bicyclic and polycyclic strained molecules like norbonanes, endo-endo and endo-exo tetracyclic dodecanes compounds, and their respective cationic Rhodium catalysts, were prepared. Carbon-13 and Phosphorus-31 NMR were used to identify the synthesized compounds. (author)

  3. Activity of iridium-ruthenium and iridium-rhodium adsorption catalysts in decomposition of hydrogen peroxide

    International Nuclear Information System (INIS)

    Experimental data for the activities of iridium-ruthenium and iridium-rhodium adsorption catalysts in the decomposition of hydrogen peroxide are considered and the results of magnetic susceptibility measurements are presented. It is concluded that surface structures (complexes) may be formed and that micro-electronic feaures play a role in heterogeneous catalysis

  4. Mild and Site-Selective Allylation of Enol Carbamates with Allylic Carbonates under Rhodium Catalysis.

    Science.gov (United States)

    Sharma, Satyasheel; Han, Sang Hoon; Oh, Yongguk; Mishra, Neeraj Kumar; Han, Sangil; Kwak, Jong Hwan; Lee, Seok-Yong; Jung, Young Hoon; Kim, In Su

    2016-03-18

    The rhodium(III)-catalyzed mild and site-selective C-H allylation of enol carbamates with 4-vinyl-1,3-dioxolan-2-one and allylic carbonates affords allylic alcohols and terminal allylated products, respectively. The assistance of the carbamoyl directing group provides a straightforward preparation of biologically and synthetically important allylated enol carbamates. PMID:26906724

  5. Direct C-H alkylation and indole formation of anilines with diazo compounds under rhodium catalysis.

    Science.gov (United States)

    Mishra, Neeraj Kumar; Choi, Miji; Jo, Hyeim; Oh, Yongguk; Sharma, Satyasheel; Han, Sang Hoon; Jeong, Taejoo; Han, Sangil; Lee, Seok-Yong; Kim, In Su

    2015-12-18

    The rhodium(III)-catalyzed direct functionalization of aniline C-H bonds with α-diazo compounds is described. These transformations provide a facile construction of ortho-alkylated anilines with diazo malonates or highly substituted indoles with diazo acetoacetates. PMID:26458276

  6. Synthesis of 1H-Indazoles from Imidates and Nitrosobenzenes via Synergistic Rhodium/Copper Catalysis.

    Science.gov (United States)

    Wang, Qiang; Li, Xingwei

    2016-05-01

    Nitrosobenzenes have been used as a convenient aminating reagent for the efficient synthesis of 1H-indazoles via rhodium and copper catalyzed C-H activation and C-N/N-N coupling. The reaction occurred under redox-neutral conditions with high efficiency and functional group tolerance. Moreover, a rhodacyclic imidate complex has been identified as a key intermediate. PMID:27082502

  7. Rhodium-catalyzed C-C Bond Cleavage Reactions - An Update

    Czech Academy of Sciences Publication Activity Database

    Korotvička, A.; Nečas, D.; Kotora, Martin

    2012-01-01

    Roč. 16, č. 10 (2012), s. 1170-1214. ISSN 1385-2728 Grant ostatní: GA MŠk(CZ) LC06070 Institutional research plan: CEZ:AV0Z40550506 Keywords : rhodium * C-C bond cleavage * catalysis * synthesis Subject RIV: CC - Organic Chemistry Impact factor: 3.039, year: 2012

  8. Trifluoromethylallylation of Heterocyclic C-H Bonds with Allylic Carbonates under Rhodium Catalysis.

    Science.gov (United States)

    Choi, Miji; Park, Jihye; Sharma, Satyasheel; Jo, Hyeim; Han, Sangil; Jeon, Mijin; Mishra, Neeraj Kumar; Han, Sang Hoon; Lee, Jong Suk; Kim, In Su

    2016-06-01

    The rhodium(III)-catalyzed γ-trifluoromethylallylation of various heterocyclic C-H bonds with CF3-substituted allylic carbonates is described. These reactions provide direct access to linear CF3-containing allyl frameworks with complete trans-selectivity via C-H bond activation followed by a formal SN-type reaction pathway. PMID:27187625

  9. Cross-Coupling of Acrylamides and Maleimides under Rhodium Catalysis: Controlled Olefin Migration.

    Science.gov (United States)

    Sharma, Satyasheel; Han, Sang Hoon; Oh, Yongguk; Mishra, Neeraj Kumar; Lee, Suk Hun; Oh, Joa Sub; Kim, In Su

    2016-06-01

    The rhodium(III)-catalyzed direct cross-coupling reaction of electron-deficient acrylamides with maleimides is described. This protocol displays broad functional group tolerance and high efficiency, which offers a new opportunity to access highly substituted succinimides. Dependent on the substituent positions of acrylamides and reaction conditions, olefin migrated products were obtained with high regio- and stereoselectivity. PMID:27182717

  10. Graphene oxide based chiral diamine rhodium catalyst for asymmetric transfer hydrogenation of aromatic ketones

    Directory of Open Access Journals (Sweden)

    LIU Ketang

    2013-02-01

    Full Text Available Functional graphite oxide materials were synthesized through the Hummers chemical oxidation of graphite.Heterogeneous catalyst was prepared via direct grafting diamine-based chiral ligand to graphite oxide followed by the complexation with organorhodium complex.Such a chiral rhodium catalyst exhibited high catalytic activity and enantioselectivity in asymmetric transfer hydrogenation of aromatic ketones in aqueous medium under mild condition.

  11. Preparation and Characterization of Cetyl Trimethylammonium Intercalated Sericite

    Directory of Open Access Journals (Sweden)

    Hao Ding

    2014-01-01

    Full Text Available Intercalated sericite was prepared by intercalation of cetyl trimethylammonium bromide (CTAB into activated sericite through ion exchange with the following two steps: the activation of sericite by thermal modification, acid activation and sodium modification; the ion exchange intercalation of CTA+ into activated sericite. Effects of reaction time, reaction temperature, CTAB quantity, kinds of medium, and aqueous pH on the intercalation of activated sericite were examined by X-ray diffraction (XRD analysis, Fourier transform infrared (FT-IR spectroscopy, differential scanning calorimetry (DSC, and thermogravimetric analysis (TGA. The results indicated that the CTA+ entered sericite interlayers and anchored in the aluminosilicate interlayers through strong electrostatic attraction. The arrangement of CTA+ in sericite interlayers was that alkyl chain of CTA+ mainly tilted at an angle about 60° (paraffin-type bilayer and 38° (paraffin-type monolayer with aluminosilicate layers. The largest interlayer space was enlarged from 0.9 nm to 5.2 nm. The intercalated sericite could be used as an excellent layer silicate to prepare clay-polymer nanocomposites.

  12. Synthesis and Olfactory Evaluation of Bulky Moiety-Modified Analogues to the Sandalwood Odorant Polysantol®

    Directory of Open Access Journals (Sweden)

    Adolfo Sánchez

    2009-07-01

    Full Text Available Five new bulky moiety-modified analogues of the sandalwood odorant Polysantol® have been synthesized by aldol condensation of appropriate aldehydes with butanone, deconjugative α-methylation of the resulting α,β-unsaturated ketones, and reduction of the corresponding β,γ-unsaturated ketones. The final compounds were evaluated organoleptically and one of them seemed to be of special interest for its natural sandalwood scent.

  13. P53 overexpression is associated with bulky tumor and poor local control in T1 glottic cancer

    International Nuclear Information System (INIS)

    Purpose: To study the role of two possible prognostic factors, p53 and tumor bulk, and their interaction with other tumor and treatment variables in early-stage laryngeal cancer patients treated with curative radiotherapy. Methods: One hundred two patients with T1N0M0 squamous cell carcinoma of the glottic larynx treated with definitive radiotherapy were analyzed. p53 status in pretreatment biopsy specimens was assessed by immunohistochemistry (IHC) using mouse monoclonal antibody DO-7. Tumors were classified as small surface lesions or bulky tumors. All tumor-related and treatment-related variables which might influence the outcome were analyzed. Local control after definitive radiotherapy was the end point of the study. Results: The local control at 5 years for the entire group of patients was 78% (80/102) and 91% (93/102) after surgical salvage. p53 overexpression by IHC was seen in 37% (38/102) of patients. Tumors were classified as small volume in 69 (68%) and bulky in 33 (32%) patients. Five-year local control was 48% for p53-positive patients as compared to 94% for p53-negative patients (p = 0.0001). Tumor bulk was the other important prognostic factor, with 5-year local control of 91% for small tumors and 48% for bulky tumors (p = 0.0001). Patients who had both p53 positivity and bulky tumors did worse, with a 5-year local control of 23% as compared to 92% for all other groups combined (p = 0.0001). Among other variables, only the length of radiation time was of borderline significance. Conclusion: Both p53 overexpression and tumor bulk are independent prognostic factors for local control in early-stage glottic cancer treated with curative radiotherapy. The precise relationship between a genetic event, the p53 mutation, and an observable phenotype expression such as tumor bulk needs to be further defined

  14. Studies in the capacitance properties of diaminoalkane-intercalated graphene

    International Nuclear Information System (INIS)

    A series of diaminoalkane-intercalated graphenes (DIGs) are successfully synthesized by intercalating graphite oxide with diaminoalkanes, followed by a reduction process using hydrazine as a reductant at room temperature. The as-prepared intercalated graphite oxides (DIGOs) and their reduced products are characterized using a variety of approaches such as X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy and elemental analysis. Electrochemical tests show that the specific capacitances of DIGOs and DIGs decrease with the increase of the interlayer distance, and that the DIGs possess larger capacitance than DIGOs after hydrazine reduction. The ion diffusion in the DIGOs/DIGs follows pseudo-second-order kinetics and is dominated mainly by their pore sizes

  15. Intercalation of paracetamol into the hydrotalcite-like host

    International Nuclear Information System (INIS)

    Hydrotalcite-like compounds are often used as host structures for intercalation of various anionic species. The product intercalated with the nonionic, water-soluble pharmaceuticals paracetamol, N-(4-hydroxyphenyl)acetamide, was prepared by rehydration of the Mg–Al mixed oxide obtained by calcination of hydrotalcite-like precursor at 500 °C. The successful intercalation of paracetamol molecules into the interlayer space was confirmed by powder X-ray diffraction and infrared spectroscopy measurements. Molecular simulations showed that the phenolic hydroxyl groups of paracetamol interact with hydroxide sheets of the host via the hydroxyl groups of the positively charged sites of Al-containing octahedra; the interlayer water molecules are located mostly near the hydroxide sheets. The arrangement of paracetamol molecules in the interlayer is rather disordered and interactions between neighboring molecules cause their tilting towards the hydroxide sheets. Dissolution tests in various media showed slower release of paracetamol intercalated in the hydrotalcite-like host in comparison with tablets containing the powdered pharmaceuticals. - Graphical abstract: Molecular simulations showed disordered arrangement of paracetamol molecules in the interlayer; most of the interlayer water molecules are located near the hydroxide sheets.▪ Highlights: ► Paracetamol was intercalated in Mg–Al hydrotalcite-like host by rehydration/reconstruction procedure. ► Paracetamol phenolic groups interact with positively charged sites in hydroxide sheets. ► Molecular simulations showed disordered arrangement of guest molecules in the interlayer. ► Slower release of paracetamol intercalated in the hydrotalcite-like host was observed.

  16. Hydrocarbon chain conformation in an intercalated surfactant monolayer and bilayer

    Indian Academy of Sciences (India)

    N V Venkataraman; S Vasudevan

    2001-10-01

    Cetyl trimethyl ammonium (CTA) ions have been confined within galleries of layered CdPS3 at two different grafting densities. Low grafting densities are obtained on direct intercalation of CTA ions into CdPS3 to give Cd0.93PS3(CTA)0.14. Intercalation occurs with a lattice expansion of 4.8 Å with the interlamellar surfactant ion lying flat forming a monolayer. Intercalation at higher grafting densities was effected by a two-step ion-exchange process to give Cd0.83PS3(CTA)0.34, with a lattice expansion of 26.5 Å. At higher grafting densities the interlamellar surfactant ions adopt a tilted bilayer structure. 13C NMR and orientation-dependent IR vibrational spectroscopy on single crystals have been used to probe the conformation and orientation of the methylene ‘tail’ of the intercalated surfactant in the two phases. In the monolayer phase, the confined methylene chain adopts an essentially all-trans conformation with most of the trans chain aligned parallel to the gallery walls. On lowering the temperature, molecular plane aligns parallel, so that the methylene chain lies flat, rigid and aligned to the confining surface. In the bilayer phase, most bonds in the methylene chain are in trans conformation. It is possible to identify specific conformational sequences containing a gauche bond, in the interior and termini of the intercalated methylene. These high energy conformers disappear on cooling leaving all fifteen methylene units of the intercalated cetyl trimethyl ammonium ion in trans conformational registry at 40 K.

  17. Homoleptic mono- and dinuclear cationic alkoxydiphosphazane derivatives of rhodium

    International Nuclear Information System (INIS)

    Treatment of the solvento species [Rh(C8H12)(solvent)2][SbF6] (solvent = methanol, ethanol, or tetrahydrofuran) with a twice-molar amount of the diphosphazane ligands (RO)2PN(R') P(OR)2 (R' = Me or Et; R = Me, Et, or Pri) in the appropriate solvent leads to the ready formation of monocationic [Rh{(RO)2PN(R')P(OR)2}2]+ and/or dicationic [Rh2{μ-(RO)2PN(R')P(OR)2}2{(RO)2PN(R')P(OR)2}2]2+ hexafluoroantimonate salts, with the tendency to afford dinuclear derivatives decreasing along the series Me>Et>Pri. Carbon monoxide readily forms addition products with these ionic species, giving rise to five-coordinate derivatives of the type [Rh(CO){(RO)2PN(R')P (OR)2}2][SbF6] in the case of the mononuclear derivatives, and inserting across the two rhodium atoms to afford [Rh2(μ-CO){μ-(MeO)2PN(Et)P(OMe)2}2{(MeO)2PN(Et)P(OMe)2}2][SbF6]2 in the case of [Rh2{μ-(MeO)2PN (Et)P(OMe)2}2{(MeO)2PN(Et)P(OMe)2}2][SbF6]2. These mono- and dicationic derivatives also react readily with iodine affording [RhI2{(RO)2PN(R')P(OR)2}2][SbF6] and [Rh2(μ-I){μ-(MeO)2PN(Et)P(OMe)2}2{(MeO)2 PN(Et)P(OMe)2}2][SbF6]n (n = 2 or 3) respectively. The coordination behaviour of the diphosphorus ligands (MeO)2PCH2P(OMe)2 and Me2PCH2PMe2 towards [Rh(C8 H12)(solvent)2][SbF6] has also been investigated. 1 fig., 1 tab., 19 refs

  18. Double hydrophosphination of alkynes promoted by rhodium: the key role of an N-heterocyclic carbene ligand.

    Science.gov (United States)

    Di Giuseppe, Andrea; De Luca, Roberto; Castarlenas, Ricardo; Pérez-Torrente, Jesús J; Crucianelli, Marcello; Oro, Luis A

    2016-04-12

    The regioselective double hydrophosphination of alkynes mediated by rhodium catalysts is presented. The distinctive stereoelectronic properties of the NHC ligand prevent the catalyst deactivation by diphosphine coordination thereby allowing for the closing of a productive catalytic cycle. PMID:27022648

  19. The concise synthesis of chiral tfb ligands and their application to the rhodium-catalyzed asymmetric arylation of aldehydes

    OpenAIRE

    Nishimura, Takahiro; Kumamoto, Hana; Nagaosa, Makoto; Hayashi, Tamio

    2009-01-01

    New C2-symmetric tetrafluorobenzobarrelene ligands were prepared and applied successfully to the rhodium-catalyzed asymmetric addition of arylboronic acids to aromatic aldehydes giving chiral diarylmethanols in high yield with high enantioselectivity.

  20. Efficient Synthesis of Spirobarbiturates and Spirothiobarbiturates Bearing Cyclopropane Rings by Rhodium(II)-Catalyzed Reactions of Cyclic Diazo Compounds

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xue; Lee, Yong Rok [Yeungnam Univ., Gyeongsan (Korea, Republic of)

    2013-06-15

    Rhodium(II)-catalyzed reactions of cyclic diazo compounds derived from barbituric acid and thiobarbituric acid with a variety of styrene moieties were examined. These reactions provide rapid synthetic routes to the preparations of spirobarbiturates and spirothiobarbiturates bearing cyclopropane rings.

  1. Ruthenium and rhodium complexes with chiral P-donor ligands as catalysts of enantioselective hydrogenation of ketoesters

    International Nuclear Information System (INIS)

    The use of ruthenium(II) and rhodium(III) complexes with chiral P-donor ligands as catalysts of asymmetric hydrogenation of α-, β- and γ-ketoesters is considered. The attention is focused on highly enantioselective processes.

  2. Modification of Nanocomposites by Melting Intercalation of Polypropylene in Montmorillonite

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The polypropylene was modified by ultraviolet irradiation.The polypropylene-montmorillonite nanocomposites were prepared by direct melting intercalation of polypropylene powders.The structure of polypropylene,the polyproprlene irradiated, montmorillinote and polypropylene-montmorillonite composites were studied by XRD, IR and DSC. The results show that the PP molecules can are oxidized during ultraviolet irradiation,melt polypropylene can intercalate into montmorillonite layer.As a result,the layered distance (d001) of montmorillonite increases, and the melt absorption peak of polypropylene in layer is eliminated.

  3. Selective catalytic reduction system and process for treating NOx emissions using a palladium and rhodium or ruthenium catalyst

    Science.gov (United States)

    Sobolevskiy, Anatoly; Rossin, Joseph A.; Knapke, Michael J.

    2011-07-12

    A process for the catalytic reduction of nitrogen oxides (NOx) in a gas stream (29) in the presence of H.sub.2 is provided. The process comprises contacting the gas stream with a catalyst system (38) comprising zirconia-silica washcoat particles (41), a pre-sulfated zirconia binder (44), and a catalyst combination (40) comprising palladium and at least one of rhodium, ruthenium, or a mixture of ruthenium and rhodium.

  4. Separation of platinum and rhodium from chloride solutions containing aluminum, magnesium and iron using solvent extraction and precipitation methods.

    Science.gov (United States)

    Raju, B; Kumar, J Rajesh; Lee, Jin-Young; Kwonc, Hyuk-Sung; Kantam, M Lakshmi; Reddy, B Ramachandra

    2012-08-15

    The solvent extraction and precipitation methods have been used to develop a process to separate platinum and rhodium from a synthetic chloride solutions containing other associated metals such as (mg/L): Pt-364, Rh-62, Al-13880, Mg-6980, Fe-1308 at chloride ([Pt(tu)(4)]Cl(2)). The selective precipitation of rhodium was performed with (NH(4))(2)S from platinum free raffinate with a recovery of >99%. PMID:22664260

  5. Activity of iridium-ruthenium and iridium-rhodium adsorption catalysts in liquid-phase hydrogenation of cyclohexene

    International Nuclear Information System (INIS)

    The activity of Ru-, Rh-, (Ir+nRu)- and (Ir+nRh)-catalysts on silicon dioxide in the cyclohexene hydration reaction has been studied. It is shown that hydration proceeds on a diatomic active centre (Me)2/(carrier). The observed activity of the iridium-rhodium and iridium-ruthenium catalysts exceeds the additive one. The activation effect is due to the possible formation of iridium-ruthenium and iridium-rhodium surface structures of the type of bertholides

  6. Enantioselective Synthesis of Spiroindenes by Enol-Directed Rhodium(III)-Catalyzed C–H Functionalization and Spiroannulation

    Science.gov (United States)

    Reddy Chidipudi, Suresh; Burns, David J; Khan, Imtiaz; Lam, Hon Wai

    2015-01-01

    Chiral cyclopentadienyl rhodium complexes promote highly enantioselective enol-directed C(sp2)-H functionalization and oxidative annulation with alkynes to give spiroindenes containing all-carbon quaternary stereocenters. High selectivity between two possible directing groups, as well as control of the direction of rotation in the isomerization of an O-bound rhodium enolate into the C-bound isomer, appear to be critical for high enantiomeric excesses. PMID:26404643

  7. Rhodium(III)-catalyzed C-C coupling of 7-azaindoles with vinyl acetates and allyl acetates.

    Science.gov (United States)

    Li, Shuai-Shuai; Wang, Cheng-Qi; Lin, Hui; Zhang, Xiao-Mei; Dong, Lin

    2016-01-01

    The behaviour of electron-rich alkenes with 7-azaindoles in rhodium(III)-catalyzed C-H activation is investigated. Various substituted vinyl acetates and allyl acetates as coupling partners reacted smoothly providing a wide variety of 7-azaindole derivatives, and the selectivity of the coupling reaction is alkene-dependent. In addition, the approaches of rhodium(III)-catalyzed dehydrogenative Heck-type reaction (DHR) and carbonylation reaction were quite novel and simple. PMID:26553424

  8. A treatment planning approach to spatially fractionated megavoltage grid therapy for bulky lung cancer

    International Nuclear Information System (INIS)

    The purpose of this study was to explore the treatment planning methods of spatially fractionated megavoltage grid therapy for treating bulky lung tumors using multileaf collimator (MLC). A total of 5 patients with lung cancer who had gross tumor volumes ranging from 277 to 635 cm3 were retrospectively chosen for this study. The tumors were from 6.5 to 9.6 cm at shortest dimension. Several techniques using either electronic compensation or intensity-modulated radiation therapy (IMRT) were used to create a variety of grid therapy plans on the Eclipse treatment planning system. The dose prescription point was calculated to the volume, and a dose of 20 Gy with 6-MV/15-MV beams was used in each plan. The dose-volume histogram (DVH) curves were obtained to evaluate dosimetric characteristics. In addition, DVH curves from a commercially available cerrobend grid collimator were also used for comparison. The linear-quadratic radiobiological response model was used to assess therapeutic ratios (TRs) and equivalent uniform doses (EUD) for all generated plans. A total of 6 different grid therapy plans were created for each patient. Overall, 4 plans had different electronic compensation techniques: Ecomps-Tubes, Ecomps-Circles, Ecomps-Squares, and Ecomps-Weave; the other 2 plans used IMRT and IMRT-Weave techniques. The DVH curves and TRs demonstrated that these MLC-based grid therapy plans can achieve dosimetric properties very similar to those of the cerrobend grid collimator. However, the MLC-based plans have larger EUDs than those with the cerrobend grid collimator. In addition, the field shaping can be performed for targets of any shape in MLC-based plans. Thus, they can deliver a more conformal dose to the targets and spare normal structures better than the cerrobend grid collimator can. The plans generated by the MLC technique demonstrated the advantage over the standard cerrobend grid collimator on accommodating targets and sparing normal structures. Overall, 6

  9. A treatment planning approach to spatially fractionated megavoltage grid therapy for bulky lung cancer

    Energy Technology Data Exchange (ETDEWEB)

    Costlow, Heather N. [Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, IN (United States); Zhang, Hualin, E-mail: hzhang@nmh.org [Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, IN (United States); Department of Radiation Oncology, Northwestern University Feinberg School of Medicine, Northwestern University, Northwestern Memorial Hospital, Chicago, IL (United States); Das, Indra J. [Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, IN (United States)

    2014-10-01

    The purpose of this study was to explore the treatment planning methods of spatially fractionated megavoltage grid therapy for treating bulky lung tumors using multileaf collimator (MLC). A total of 5 patients with lung cancer who had gross tumor volumes ranging from 277 to 635 cm{sup 3} were retrospectively chosen for this study. The tumors were from 6.5 to 9.6 cm at shortest dimension. Several techniques using either electronic compensation or intensity-modulated radiation therapy (IMRT) were used to create a variety of grid therapy plans on the Eclipse treatment planning system. The dose prescription point was calculated to the volume, and a dose of 20 Gy with 6-MV/15-MV beams was used in each plan. The dose-volume histogram (DVH) curves were obtained to evaluate dosimetric characteristics. In addition, DVH curves from a commercially available cerrobend grid collimator were also used for comparison. The linear-quadratic radiobiological response model was used to assess therapeutic ratios (TRs) and equivalent uniform doses (EUD) for all generated plans. A total of 6 different grid therapy plans were created for each patient. Overall, 4 plans had different electronic compensation techniques: Ecomps-Tubes, Ecomps-Circles, Ecomps-Squares, and Ecomps-Weave; the other 2 plans used IMRT and IMRT-Weave techniques. The DVH curves and TRs demonstrated that these MLC-based grid therapy plans can achieve dosimetric properties very similar to those of the cerrobend grid collimator. However, the MLC-based plans have larger EUDs than those with the cerrobend grid collimator. In addition, the field shaping can be performed for targets of any shape in MLC-based plans. Thus, they can deliver a more conformal dose to the targets and spare normal structures better than the cerrobend grid collimator can. The plans generated by the MLC technique demonstrated the advantage over the standard cerrobend grid collimator on accommodating targets and sparing normal structures. Overall, 6

  10. Lithium intercalation/de-intercalation behavior of a composite Sn/C thin film fabricated by magnetron sputtering

    Institute of Scientific and Technical Information of China (English)

    ZHAO Lingzhi; HU Shejun; LI Weishan; LI Liming; HOU Xianhua

    2008-01-01

    A tin film of 320 nm in thickness on Cu foil and its composite film with graphite of~50 nm in thickness on it were fabricated by magnetron sputtering.The surface morphology,composition,surface distributions of alloy elements,and lithium intercalation/de-intercalation behaviors of the fabricated films were characterized by X-ray diffraction (XRD),scanning electron microscopy (SEM),electron probe microanalyzer (EPMA),X-ray photoelectron spectroscopy (XPS),inductively coupled plasma atomic emission spectrometry (ICP),cyclic voltammetry (CV),and galvanostatic charge/discharge (GC) measurements.It is found that the lithium intercalation/de-intercalation behavior of the Sn film can be significantly improved by its composite with graphite.With cycling,the discharge capacity of the Sn film without composite changes from 570 mAh/g of the 2nd cycle to 270 mAh/g of the 20th cycle,and its efficiency for the discharge and charge is between 90% and 95%.Nevertheless,the discharge capacity of the composite Sn/C film changes from 575 mAh/g of the 2nd cycle to 515 mAh/g of the 20th cycle,and its efficiency for the discharge and charge is between 95% and 100%.The performance improvement of tin by its composite with graphite is ascribed to the retardation of the bulk fin cracking from volume change during lithium intercalation and de-intercalation,which leads to the pulverization of fin.

  11. Recovery of bulky DNA adducts by the regular and a modified 32P-postlabelling assay; influence of the DNA-isolation method.

    OpenAIRE

    Kovács, Katalin; Anna, Lívia; Rudnai, Péter; Schoket, Bernadette

    2011-01-01

    Bulky DNA adducts are widely used as biomarkers of human exposure to complex mixtures of environmental genotoxicants including polycyclic aromatic hydrocarbons. The 32P-postlabelling method is highly sensitive for the detection of bulky DNA adducts, but its relatively low throughput poses limits to its use in large-scale molecular epidemiological studies. The objectives of this study were to compare the impact of DNA-sample preparation with a commercial DNA-isolation kit or with the classical...

  12. Intercalation of papain enzyme into hydrotalcite type layered double hydroxide

    Science.gov (United States)

    Zou, N.; Plank, J.

    2012-09-01

    Intercalation of proteolytic enzyme papain into hydrotalcite type LDH structure was achieved by controlled co-precipitation at pH=9.0 in the presence of papain. Characterization of the MgAl-papain-LDH phase was carried out using X-ray powder diffraction (XRD), elemental analysis, infrared spectroscopy (IR) and thermogravimetry (TG). According to XRD, papain was successfully intercalated. The d-value for the basal spacing of MgAl-papain-LDH was found at ˜5.3 nm. Consequently, original papain (hydrodynamic diameter ˜7.2 nm) attains a compressed conformation during intercalation.Formation of MgAl-papain-LDH was confirmed by elemental analysis and transmission electron microscopy (TEM). Under SEM, MgAl-papain-LDH phases appear as nanothin platelets which are intergrown to flower-like aggregates. Steric size and activity of the enzyme was retained after deintercalation from MgAl-LDH framework, as was evidenced by light scattering and UV/vis measurements. Thus, papain is not denatured during intercalation, and LDH is a suitable host structure which can provide a time-controlled release of the biomolecule.

  13. Enantiospecific kinking of DNA by a partially intercalating metal complex

    KAUST Repository

    Reymer, Anna

    2012-01-01

    Opposite enantiomers of [Ru(phenanthroline) 3] 2+ affect the persistence length of DNA differently, a long speculated effect of helix kinking. Our molecular dynamics simulations confirm a substantial change of duplex secondary structure produced by wedge-intercalation of one but not the other enantiomer. This effect is exploited by several classes of DNA operative proteins. © The Royal Society of Chemistry 2012.

  14. Intercalation of paracetamol into the hydrotalcite-like host

    Science.gov (United States)

    Kovanda, František; Maryšková, Zuzana; Kovář, Petr

    2011-12-01

    Hydrotalcite-like compounds are often used as host structures for intercalation of various anionic species. The product intercalated with the nonionic, water-soluble pharmaceuticals paracetamol, N-(4-hydroxyphenyl)acetamide, was prepared by rehydration of the Mg-Al mixed oxide obtained by calcination of hydrotalcite-like precursor at 500 °C. The successful intercalation of paracetamol molecules into the interlayer space was confirmed by powder X-ray diffraction and infrared spectroscopy measurements. Molecular simulations showed that the phenolic hydroxyl groups of paracetamol interact with hydroxide sheets of the host via the hydroxyl groups of the positively charged sites of Al-containing octahedra; the interlayer water molecules are located mostly near the hydroxide sheets. The arrangement of paracetamol molecules in the interlayer is rather disordered and interactions between neighboring molecules cause their tilting towards the hydroxide sheets. Dissolution tests in various media showed slower release of paracetamol intercalated in the hydrotalcite-like host in comparison with tablets containing the powdered pharmaceuticals.

  15. Lithium intercalation in perovskite and hexagonal tungsten bronze derivatives

    International Nuclear Information System (INIS)

    Lithium has been intercalated chemically and electrochemically in LnNb3O9 (Ln = La,Nd) perovskite-type phases and LiW3O9F which can be considered as a hexagonal tungsten bronze derivative. The crystallographic formula of the LnNb3O9 starting material is described

  16. Strontium and barium phenylphosphonates as host materials for intercalation chemistry

    Czech Academy of Sciences Publication Activity Database

    Beneš, L.; Melánová, Klára; Svoboda, Jan; Zima, Vítězslav; Růžička, A.

    Praha : Ústav fyzikální chemie Jaroslava Heyrovského AV ČR,v.v.i, 2015. P01. [Workshop on Layered Materials. 15.09.2015-19.09.2015, Třešť] Institutional support: RVO:61389013 Keywords : intercalation * phosphonates * alkanediols Subject RIV: CA - Inorganic Chemistry

  17. Capacitive Sensing of Intercalated H2O Molecules Using Graphene.

    Science.gov (United States)

    Olson, Eric J; Ma, Rui; Sun, Tao; Ebrish, Mona A; Haratipour, Nazila; Min, Kyoungmin; Aluru, Narayana R; Koester, Steven J

    2015-11-25

    Understanding the interactions of ambient molecules with graphene and adjacent dielectrics is of fundamental importance for a range of graphene-based devices, particularly sensors, where such interactions could influence the operation of the device. It is well-known that water can be trapped underneath graphene and its host substrate; however, the electrical effect of water beneath graphene and the dynamics of how the interfacial water changes with different ambient conditions has not been quantified. Here, using a metal-oxide-graphene variable-capacitor (varactor) structure, we show that graphene can be used to capacitively sense the intercalation of water between graphene and HfO2 and that this process is reversible on a fast time scale. Atomic force microscopy is used to confirm the intercalation and quantify the displacement of graphene as a function of humidity. Density functional theory simulations are used to quantify the displacement of graphene induced by intercalated water and also explain the observed Dirac point shifts as being due to the combined effect of water and oxygen on the carrier concentration in the graphene. Finally, molecular dynamics simulations indicate that a likely mechanism for the intercalation involves adsorption and lateral diffusion of water molecules beneath the graphene. PMID:26502269

  18. Stroncium methylphosphonate and phenylphosphonate-structure and intercalation behavior

    Czech Academy of Sciences Publication Activity Database

    Melánová, Klára; Beneš, L.; Svoboda, Jan; Zima, Vítězslav; Růžička, A.

    Strasbourg: European Materials Research Society, 2010. s. 49-50. [E- MRS 2010 Spring Meeting. 07.06.2010 - 11. 06. 2010, Strasbourg] R&D Projects: GA ČR GA203/08/0208 Institutional research plan: CEZ:AV0Z40500505 Keywords : intercalation * layered phosphonates * stontium Subject RIV: CD - Macromolecular Chemistry

  19. Methotrexate intercalated ZnAl-layered double hydroxide

    International Nuclear Information System (INIS)

    The anticancerous drug methotrexate (MTX) has been intercalated into an ZnAl-layered double hydroxide (LDH) using an anion exchange technique to produce LDH-MTX hybrids having particle sizes in the range of 100-300 nm. X-ray diffraction studies revealed increases in the basal spacings of ZnAl-LDH-MTX hybrid on MTX intercalation. This was corroborated by the transmission electron micrographs, which showed an increase in average interlayer spacing from 8.9 A in pristine LDH to 21.3 A in LDH-MTX hybrid. Thermogravimetric analyses showed an increase in the decomposition temperature for the MTX molecule in the LDH-MTX hybrid indicating enhanced thermal stability of the drug molecule in the LDH nanovehicle. The cumulative release profile of MTX from ZnAl-LDH-MTX hybrids in phosphate buffer saline (PBS) at pH 7.4 was successfully sustained for 48 h following Rigter-Peppas model release kinetics via diffusion. - Graphical abstract: ZnAl-layered double hydroxide intercalated with methotrexate (∼34% loading) promises the possibility of use of ZnAl-LDH material as drug carrier and in controlled delivery. Highlights: → ZnAl-layered double hydroxide methotrexate nanohybrid has been synthesized. → XRD and TEM studies on nanohybrid revealed successful intercalation of methotrexate. → TG and CHN analyses showed ∼34 wt% of methotrexate loading into the nanohybrid. → Possibility of use of ZnAl-LDH material as drug carrier and in delivery.

  20. Intercalation chemistry of layered functionalized phosphonates of tetravalent metals

    Czech Academy of Sciences Publication Activity Database

    Zima, Vítězslav; Melánová, Klára; Svoboda, Jan; Beneš, L.

    Pardubice : University of Pardubice, 2012. s. 117. ISBN 978-80-7395-499-4. [10th International Conference Solid State Chemistry 2012. 10.06.2012-14.06.2012, Pardubice] R&D Projects: GA ČR(CZ) 203/08/0208 Institutional support: RVO:61389013 Keywords : metal phosphonate * layered phosphates * intercalation Subject RIV: CA - Inorganic Chemistry

  1. Intercalation chemistry of layered vanadyl phosphate: a review

    Czech Academy of Sciences Publication Activity Database

    Beneš, L.; Melánová, Klára; Svoboda, Jan; Zima, Vítězslav

    2012-01-01

    Roč. 73, 1-4 (2012), 33-53. ISSN 0923-0750 Institutional research plan: CEZ:AV0Z40500505 Keywords : vanadyl phosphate * intercalation * layered phosphates Subject RIV: CA - Inorganic Chemistry Impact factor: 1.399, year: 2012

  2. [Raman and infrared spectrograms of organic borate intercalated hydrotalcite].

    Science.gov (United States)

    Zhang, Jing-Yu; Bai, Zhi-Min; Zhao, Dong

    2013-03-01

    The pattern of X-ray diffraction, the Raman and infrared spectra of organic borate intercalated hydrotalcite were discussed. The well crystallized zinc-aluminum layered double hydroxides (Zn-Al LDHs) intercalated by carbonate ions and borate ions were respectively prepared by co-precipitation method. Patterns of X-ray diffraction showed that the (003) reflection of borate-LDHs was sharp and symmetric and shifted to lower angle than that of carbonate-LDHs. The gallery height of borate-LDHs increased from 0. 28 nm to 0.42 nm after intercalation, indicating that interlayered carbonate ions were substituted by borate anions. The Raman and IR spectra showed that specific bands of carbonate ions in the borate-LDHs disappeared, but with the presence of B3O3(OH)4- X B4O5(OH)4(2-) and B(OH)4- in the interlayer galleries. The hydroxide interlayer anions had a significant influence on the band positions in Raman and infrared spectra of modes related to the hydroxyl group. Our results indicate that single phase and pure borate-pillared LDHs can be obtained using tributyl orthoborate as intercalating agents, and the change in the structure and nature of hydrotalcite can be detected precisely by Raman spectroscopy. PMID:23705437

  3. Technical Report-Final-Electrochemistry of Nanostructured Intercalation Hosts

    Energy Technology Data Exchange (ETDEWEB)

    Professor William H. Smyrl, Principal Investigator

    2009-03-09

    We have shown that: (1) Li+ ions are inserted reversibly, without diffusion control, up to the level of at least 4 moles Li+ ions per mole for V2O5, in the aerogel (ARG) form (500 m2/g specific surface area) and aerogel-like (ARG-L) form (200 m2/g specific surface area)(6,7,1,2); (2) polyvalent cations (Al+3, Mg+2, Zn+2) may be intercalated reversibly into V2O5 (ARG) with high capacity (approaching 4 equivalents/mole V2O5 (ARG)) for each (5); (3) dopant cations such as Ag+ and Cu+2 increase the conductivity of V2O5 (XRG) up to three orders of magnitude(3), they are electrochemically active – showing reduction to the metallic-state in parallel to intercalation of Li+ ions – but are not released to the electrolyte upon oxidation and Li+ ion release (Cu+2 ions are reduced to Cu metal and reoxidized to Cu+2 in Li+ ion insertion/release cycles, but the copper ions are not released to the electrolyte over more than 400 cycles of the XRG form); (4) we have shown that Cu+2 ion (dopant) and Zn+2 ions (chemical insertion and dopant) occupy the same intercalation site inV2O5 xerogel and aerogel(4); (5) the reversible intercalation of Zn+2, Mg+2, and Al+3 in the ARG(11) indicates that these cations are “mobile”, but that Cu+2 ions and Ag+ ions are “immobile” in the xerogel, i.e., the latter ions are not exchanged with the electrolyte in Li+ ion intercalation cycling(3).

  4. Eradicative brachytherapy with hyaluronate gel injection into pararectal space in treatment of bulky vaginal stump recurrence of uterine cancer

    International Nuclear Information System (INIS)

    The purpose of this study is to develop a procedure for eradicative brachytherapy that can deliver a curative boost dose to bulky (>4 cm) vaginal stump recurrence of uterine cancer without risk of damaging surrounding organs. We separated risk organs (the rectum and sigmoid) from the target during brachytherapy, with a hyaluronate gel injection into the pararectal space via the percutaneous paraperineal approach under local anesthesia. The rectum anchored to the sacrum by native ligament was expected to shift posteriorly. We encountered a patient with bulky stump recurrence of uterine cancer, approximately 8 cm in maximum diameter. She was complaining of abdominal pain and constipation due to bowel encasement. Following 50 Gy of external beam radiotherapy, we applied a single fraction of brachytherapy under gel separation and delivered 14.5 Gy (50.8 GyE: equivalent dose in 2-Gy fraction calculated with linear quadratic model at α/β=3) to the target. The gel injection procedure was completed in 30 min without complications. A total irradiation dose of 100.8 GyE was delivered to the target and the cumulative minimum dose to the most irradiated rectosigmoidal volume of 2 cc (cumulative D2cc) was calculated as 58.5 GyE with gel injection, and was estimated to be 96 GyE without. Over three years, the local stump tumor has completely disappeared, with no complications. Brachytherapy with a pararectal gel injection can be a safe and effective eradicative option for bulky vaginal stump recurrence. (author)

  5. High-Density Chemical Intercalation of Zero-Valent Copper into Bi 2 Se 3 Nanoribbons

    KAUST Repository

    Koski, Kristie J.

    2012-05-09

    A major goal of intercalation chemistry is to intercalate high densities of guest species without disrupting the host lattice. Many intercalant concentrations, however, are limited by the charge of the guest species. Here we have developed a general solution-based chemical method for intercalating extraordinarily high densities of zero-valent copper metal into layered Bi 2Se 3 nanoribbons. Up to 60 atom % copper (Cu 7.5Bi 2Se 3) can be intercalated with no disruption to the host lattice using a solution disproportionation redox reaction. © 2012 American Chemical Society.

  6. Modeling the effect of intercalators on the high-force stretching behavior of DNA

    CERN Document Server

    Schakenraad, Koen; Biebricher, Andreas; Wuite, Gijs; Storm, Cornelis; van der Schoot, Paul

    2015-01-01

    DNA is structurally and mechanically altered by the binding of intercalator molecules. Intercalation strongly affects the force-extension behavior of DNA, in particular the overstretching transition. We present a statistical model that captures all relevant findings of recent force-extension experiments. Two predictions from our model are presented. The first suggests the existence of a novel hyper-stretching regime in the presence of intercalators and the second, a linear dependence of the overstretching force on intercalator concentration, is verified by re-analyzing available experimental data. Our model pins down the physical principles that govern intercalated DNA mechanics, providing a predictive understanding of its limitations and possibilities.

  7. Formation Energies of the Lithium Intercalations in MoS2

    Institute of Scientific and Technical Information of China (English)

    Aiyu LI; Huiying LIU; Zizhong ZHU; Meichun HUANG; Yong YANG

    2006-01-01

    First-principles calculations have been performed to study the lithium intercalations in MoS2. The formation energies, changes of volumes, electronic structures and charge densities of the lithium intercalations in MoS2 are presented. Our calculations show that during lithium intercalations in MoS2, the lithium intercalation formation energies per lithium atom are between 2.5 eV to 3.0 eV, The volume expansions of MoS2 due to lithium intercalations are relatively small

  8. Rhodium and copper-catalyzed asymmetric conjugate addition of alkenyl nucleophiles.

    Science.gov (United States)

    Müller, Daniel; Alexakis, Alexandre

    2012-12-25

    Since the initial reports in the mid-90s, metal catalyzed asymmetric conjugate addition (ACA) reactions evolved as an important tool for the synthetic chemist. Most of the research efforts have been done in the field of rhodium and copper catalyzed ACA reactions employing aryl and alkyl nucleophiles. Despite the great synthetic value of the double bond, the addition of alkenyl nucleophiles remains insufficiently explored. In this account, an overview of the developments in the field of rhodium and copper catalyzed ACA reactions with organometallic alkenyl reagents (B, Mg, Al, Si, Zr, Sn) will be provided. The account is intended to give a comprehensive overview of all the existing methods. However, in many cases only selected examples are displayed in order to facilitate comparison of different ligands and methodologies. PMID:23096501

  9. Radiotracer method for quantifying the amount of platinum and rhodium deposited in automotive catalytic converters

    International Nuclear Information System (INIS)

    Radiotracer methods have been developed to quantify the amount of platinum and rhodium deposited on automotive catalytic converters as a function of production conditions. In particular, this study determined the effects of selective adsorption and evaporation processes on the aqueous impregnation of converters with platinum group metal salts. The radiotracers used in this study, 191Pt and 105Rh, were produced by thermal neutron activation of Pt and Ru. Chemical processing was performed to remove undesired radioactive products and to ensure that each tracer was in its appropriate chemical state. This radiotracer method has been shown to be capable of measuring the platinum and rhodium loading on an entire substrate with a precision better than ±0.5%. At this precision level, the influence of selective adsorption and evaporation were determined

  10. Enantioselective rhodium/ruthenium photoredox catalysis en route to chiral 1,2-aminoalcohols.

    Science.gov (United States)

    Ma, Jiajia; Harms, Klaus; Meggers, Eric

    2016-08-01

    A rhodium-based chiral Lewis acid catalyst combined with [Ru(bpy)3](PF6)2 as a photoredox sensitizer allows for the visible-light-activated redox coupling of α-silylamines with 2-acyl imidazoles to afford, after desilylation, 1,2-amino-alcohols in yields of 69-88% and with high enantioselectivity (54-99% ee). The reaction is proposed to proceed via an electron exchange between the α-silylamine (electron donor) and the rhodium-chelated 2-acyl imidazole (electron acceptor), followed by a stereocontrolled radical-radical reaction. Substrate scope and control experiments reveal that the trimethylsilyl group plays a crucial role in this reductive umpolung of the carbonyl group. PMID:27462824

  11. Spectroscopic, Thermal and Biological Studies on Some Trivalent Ruthenium and Rhodium NS Chelating Thiosemicarbazone Complexes

    Directory of Open Access Journals (Sweden)

    Vinod K. Sharma

    2007-03-01

    Full Text Available The synthetic, spectroscopic, and biological studies of sixteen ring-substituted 4-phenylthiosemicarbazones and 4-nitrophenyl-thiosemicarbazones of anisaldehyde, 4-chlorobenzaldehyde, 4-fluorobenzaldehyde, and vanillin with ruthenium(III and rhodium(III chlorides are reported here. Their structures were determined on the basis of the elemental analyses, spectroscopic data (IR, electronic, H1 and C13 NMR along with magnetic susceptibility measurements, molar conductivity and thermogravimetric analyses. Electrical conductance measurement revealed a 1:3 electrolytic nature of the complexes. The resulting colored products are monomeric in nature. On the basis of the above studies, three ligands were suggested to be coordinated to each metal atom by thione sulphur and azomethine nitrogen to form low-spin octahedral complexes with ruthenium(III while forming diamagnetic complexes with rhodium(III. Both ligands and their complexes have been screened for their bactericidal activities and the results indicate that they exhibit a significant activity.

  12. Tuning the self-assembly of the bioactive dipeptide L-carnosine by incorporation of a bulky aromatic substituent

    OpenAIRE

    Castelletto, Valeria; Cheng, Ge; Greenland, Barny W.; Hamley, Ian W.; Harris, Peter J. F.

    2011-01-01

    The dipeptide L-carnosine has a number of important biological properties. Here, we explore the effect of attachment of a bulky hydrophobic aromatic unit, Fmoc [N-(fluorenyl-9-methoxycarbonyl)] on the self-assembly of Fmoc-L-carnosine, i.e., Fmoc-Beta-alanine-histidine (Fmoc-BetaAH). It is shown that Fmoc-BetaAH forms well-defined amyloid fibril containing Beta sheets above a critical aggregation concentration, which is determined from pyrene and ThT fluorescence experiments. Twisted fi...

  13. Atomic absorbtion spectrometric determination of platinum, palladium and rhodium in catalysts for automotive exhaust

    International Nuclear Information System (INIS)

    Analytical parameters of the electrothermal atomic absorption spectrometry method have been optimized for determination of platinum, palladium and rhodium in ceramic-supported catalysts for automobile exhaust gas treatment. Two chemical sample preparation methods have been proposed. In order to simplify the sample preparation procedure and to prevent the possible losses of platinum group metals the treatment of the previously ground sample with a mixture of mineral acids is recommended. (authors)

  14. Electronic states and potential energy surfaces of rhodium carbide (RhC)

    Science.gov (United States)

    Tan, Hang; Liao, Muzhen; Balasubramanian, K.

    1997-12-01

    Potential energy curves and spectroscopic constants of 23 electronic states of the rhodium carbide (RhC) have been studied using the complete-active-space multi-configuration self-consistent field (CASMCSCF) followed by first-order configuration interaction (FOCI) calculations. Multi-reference singles + doubles configuration interaction (MRSDCI) were used to determine the properties of low-lying electronic states. The nature of chemical bond formation in different states is discussed in terms of their wave function and Mulliken populations.

  15. Recovery of rhodium with a novel soft donor ligand using solvent extraction techniques in chloride media.

    Science.gov (United States)

    Bottorff, Shalina C; Powell, Ashton S; Barnes, Charles L; Wherland, Scot; Benny, Paul D

    2016-02-28

    Rhodium remains a high value platinum group metal that has key applications in electronics, catalysts, and batteries. To provide a useful tool for Rh isolation, a novel tridentate ligand utilizing soft N and S donors was designed to specifically extract Rh. The synthesis, complexation kinetics, and liquid-liquid extraction studies were performed to explore the overall process and recovery of Rh from chloride media. PMID:26837642

  16. Examining Rhodium Catalyst complexes for Use with Conducting Polymers Designed for Fuel Cells in Preparing Biosensors

    Energy Technology Data Exchange (ETDEWEB)

    Carpio, M.M.; Kerr, J.B.

    2005-01-01

    Biosensing devices are important because they can detect, record, and transmit information regarding the presence of, or physiological changes in, different chemical or biological materials in the environment. The goal of this research is to prepare a biosensing device that is effective, quick, and low cost. This is done by examining which chemicals will work best when placed in a biosensor. The first study involved experimenting on a rhodium catalyst complexed with ligands such as bipyridine and imidazole. The rhodium catalyst is important because it is reduced from RhIII to RhI, forms a hydride by reaction with water and releases the hydride to react with nicotinamide adenine dinucleotide (NAD+) to selectively produce 1,4-NADH, the reduced form of NAD+. The second study looked at different types of ketones and enzymes for the enzyme-substrate reaction converting a ketone into an alcohol. Preliminary results showed that the rhodium complexed with bipyridine was able to carry out all the reactions, while the rhodium complexed with imidazole was not able to produce and release hydrides. In addition, the most effective ketone to use is benzylacetone with the enzyme alcohol dehydrogenase from baker’s yeast. Future work includes experimenting with bis-imidazole, which mimics the structure of bipyridine to see if it has the capability to reduce and if the reduction rate is comparable to the bipyridine complex. Once all testing is completed, the fastest catalysts will be combined with polymer membranes designed for fuel cells to prepare biosensing devices that can be used in a variety of applications including ones in the medical and environmental fields.

  17. Spectroscopic, Thermal and Biological Studies on Some Trivalent Ruthenium and Rhodium NS Chelating Thiosemicarbazone Complexes

    OpenAIRE

    Vinod K Sharma; Shipra Srivastava; Ankita Srivastava

    2007-01-01

    The synthetic, spectroscopic, and biological studies of sixteen ring-substituted 4-phenylthiosemicarbazones and 4-nitrophenyl-thiosemicarbazones of anisaldehyde, 4-chlorobenzaldehyde, 4-fluorobenzaldehyde, and vanillin with ruthenium(III) and rhodium(III) chlorides are reported here. Their structures were determined on the basis of the elemental analyses, spectroscopic data (IR, electronic, 1H and 13C NMR) along with magnetic susceptibility measurements, molar conductivity and thermogravimetr...

  18. Measurement of solubilities for rhodium complexes and phosphine ligands in supercritical carbon dioxide

    OpenAIRE

    Shimoyama, Yusuke; Sonoda, Masanori; Miyazaki, Kaoru; Higashi, Hidenori; Iwai, Yoshio; ARAI, Yasuhiko

    2008-01-01

    The solubilities of phosphine ligands and rhodium (Rh) complexes in supercritical carbon dioxide were measured with Fourier transform infrared (FT-IR) spectroscopy at 320 and 333 K and several pressures. Triphenylphosphine (TPP) and tris(p-trifluoromethylphenyl)-phosphine (TTFMPP) were selected as ligands for the Rh complex. The solubilities of the fluorinated ligands and complexes were compared with those of the non-fluorinated compounds. The solubilities of ligand increased up to 10 times b...

  19. Tracking the shape-dependent sintering of platinum–rhodium model catalysts under operando conditions

    OpenAIRE

    Hejral, Uta; Müller, Patrick; Balmes, Olivier; Pontoni, Diego; Stierle, Andreas

    2016-01-01

    Nanoparticle sintering during catalytic reactions is a major cause for catalyst deactivation. Understanding its atomic-scale processes and finding strategies to reduce it is of paramount scientific and economic interest. Here, we report on the composition-dependent three-dimensional restructuring of epitaxial platinum–rhodium alloy nanoparticles on alumina during carbon monoxide oxidation at 550 K and near-atmospheric pressures employing in situ high-energy grazing incidence x-ray diffraction...

  20. Cyclization of Alkyne-Azide with Isonitrile/CO via Self-Relay Rhodium Catalysis.

    Science.gov (United States)

    Zhang, Zhen; Xiao, Fan; Huang, Baoliang; Hu, Jincheng; Fu, Bin; Zhang, Zhenhua

    2016-03-01

    A self-relay rhodium(I)-catalyzed cyclization of alkyne-azides with two σ-donor/π-acceptor ligands (isonitriles and CO) to form sequentially multiple-fused heterocycle systems via tandem nitrene transformation and aza-Pauson-Khand cyclization has been developed. In this approach, an intriguing chemoselective insertion process of isonitriles superior to CO was observed. This reaction provides an alternative strategy to synthesize functionalized pyrrolo[2,3-b]indole scaffolds. PMID:26907671

  1. Synergistic Rhodium/Copper Catalysis: Synthesis of 1,3-Enynes and N-Aryl Enaminones.

    Science.gov (United States)

    Wang, Nan-Nan; Huang, Lei-Rong; Hao, Wen-Juan; Zhang, Tian-Shu; Li, Guigen; Tu, Shu-Jiang; Jiang, Bo

    2016-03-18

    Synergistic rhodium/copper catalysis enables new three-component coupling reactions of terminal alkynes and α-diazoketones and/or arylamines, allowing dediazotized carbene C-H insertion for the synthesis of functionalized 1,3-enynes and N-aryl enaminones with high stereoselectivity. The synthetic utility of these transformations results in subsequent C-C or/and C-N bond-forming reactions to effectively build up functional molecules with potential significance. PMID:26987884

  2. Thermography and infrared spectroscopy of kaolinite-(HBO2)n intercalates

    International Nuclear Information System (INIS)

    Using the methods of X-ray phase, complex thermal analysis and infrared spectroscopy some properties of kaolinite-(HBO2)n interacalates are studied. Kaolinite-(HBO2)n intercalates are obtained by gradual intercalating of kaolinite-NH4Cl intercalates. It is shown that (HBO2)n intercalation into kaolinite is followed by a strong perturbing effect of intercalating agent on a layer of intrasurface OH groups of the mineral resulting in reorientation without noticeable dehydroxylation of the most protons from Al-OH groups to B-O bonds of intercalating agents with formation of B-OH groups structurally and energetically less homogeneous and weakly retained in the intercalate structure

  3. Mild partial deoxygenation of esters catalyzed by an oxazolinylborate-coordinated rhodium silylene.

    Science.gov (United States)

    Xu, Songchen; Boschen, Jeffery S; Biswas, Abhranil; Kobayashi, Takeshi; Pruski, Marek; Windus, Theresa L; Sadow, Aaron D

    2015-09-28

    An electrophilic, coordinatively unsaturated rhodium complex supported by borate-linked oxazoline, oxazoline-coordinated silylene, and N-heterocyclic carbene donors [{κ(3)-N,Si,C-PhB(Ox(Me2))(Ox(Me2)SiHPh)Im(Mes)}Rh(H)CO][HB(C6F5)3] (, Ox(Me2) = 4,4-dimethyl-2-oxazoline; Im(Mes) = 1-mesitylimidazole) is synthesized from the neutral rhodium silyl {PhB(Ox(Me2))2Im(Mes)}RhH(SiH2Ph)CO () and B(C6F5)3. The unusual oxazoline-coordinated silylene structure in is proposed to form by rearrangement of an unobserved isomeric cationic rhodium silylene species [{PhB(Ox(Me2))2Im(Mes)}RhH(SiHPh)CO][HB(C6F5)3] generated by H abstraction. Complex catalyzes reductions of organic carbonyl compounds with silanes to give hydrosilylation products or deoxygenation products. The pathway to these reactions is primarily influenced by the degree of substitution of the organosilane. Reactions with primary silanes give deoxygenation of esters to ethers, amides to amines, and ketones and aldehydes to hydrocarbons, whereas tertiary silanes react to give 1,2-hydrosilylation of the carbonyl functionality. In contrast, the strong Lewis acid B(C6F5)3 catalyzes the complete deoxygenation of carbonyl compounds to hydrocarbons with PhSiH3 as the reducing agent. PMID:26278517

  4. Stereoselective hydrogenation of olefins using rhodium-substituted carbonic anhydrase--a new reductase.

    Science.gov (United States)

    Jing, Qing; Okrasa, Krzysztof; Kazlauskas, Romas J

    2009-01-01

    One useful synthetic reaction missing from nature's toolbox is the direct hydrogenation of substrates using hydrogen. Instead nature uses cofactors like NADH to reduce organic substrates, which adds complexity and cost to these reductions. To create an enzyme that can directly reduce organic substrates with hydrogen, researchers have combined metal hydrogenation catalysts with proteins. One approach is an indirect link where a ligand is linked to a protein and the metal binds to the ligand. Another approach is direct linking of the metal to protein, but nonspecific binding of the metal limits this approach. Herein, we report a direct hydrogenation of olefins catalyzed by rhodium(I) bound to carbonic anhydrase (CA-[Rh]). We minimized nonspecific binding of rhodium by replacing histidine residues on the protein surface using site-directed mutagenesis or by chemically modifying the histidine residues. Hydrogenation catalyzed by CA-[Rh] is slightly slower than for uncomplexed rhodium(I), but the protein environment induces stereoselectivity favoring cis- over trans-stilbene by about 20:1. This enzyme is the first cofactor-independent reductase that reduces organic molecules using hydrogen. This catalyst is a good starting point to create variants with tailored reactivity and selectivity. This strategy to insert transition metals in the active site of metalloenzymes opens opportunities to a wider range of enzyme-catalyzed reactions. PMID:19115310

  5. Activity of rhodium-catalyzed hydroformylation: added insight and predictions from theory.

    Science.gov (United States)

    Sparta, Manuel; Børve, Knut J; Jensen, Vidar R

    2007-07-11

    We have performed a density functional theory investigation of hydroformylation of ethylene for monosubstituted rhodium-carbonyl catalysts, HRh(CO)3L, where the modifying ligand, L, is a phosphite (L = P(OMe)3, P(OPh)3, or P(OCH2CF3)3), a phosphine (L = PMe3, PEt3, PiPr3, or PPh3), or a N-heterocyclic carbene (NHC) based on the tetrahydropyrimidine, imidazol, or tetrazol ring, respectively. The study follows the Heck and Breslow mechanism. Excellent correspondence between our calculations and existing experimental information is found, and the present results constitute the first example of a realistic quantum chemical description of the catalytic cycle of hydroformylation using ligand-modified rhodium carbonyl catalysts. This description explains the mechanistic and kinetic basis of the contemporary understanding of this class of reaction and offers unprecedented insight into the electronic and steric factors governing catalytic activity. The insight has been turned into structure-activity relationships and used as guidelines when also subjecting to calculation phosphite and NHC complexes that have yet to be reported experimentally. The latter calculations illustrate that it is possible to increase the electron-withdrawing capacity of both phosphite and NHC ligands compared to contemporary ligands through directed substitution. Rhodium complexes of such very electron-withdrawing ligands are predicted to be more active than contemporary catalysts for hydroformylation. PMID:17555314

  6. Rhodium (II) cycle alkanecarboxylate: synthesis, spectroscopic and thermo analytic studies and evaluation of the antitumor potential

    International Nuclear Information System (INIS)

    Four new rhodium(II) carboxylates (cyclopropane, cyclobutane, cyclopentane, and cyclohexanecarboxylate), and other already known rhodium (II) carboxylates (acetate, propionate, butyrate, metoxyacetate, dichloroacetate, and trifluoroacetate), have been prepared for study in this work. The compounds were characterized by elementary and thermogravimetric analysis, magnetic susceptibility, and electronic, Raman, and infrared spectroscopy. The reaction of Rh CL3.aq with the sodium carboxylates was studied aiming to improve the understanding of the redox process involved. Spectroscopy studies (Raman and electronic) were made to examine the transition involved in the Rh-Rh and Rh-O bonds. The results have shown a direct relation between the force of the carboxylic acid and the Rh-O force, but show a inverse relation with the Rh-Rh bond force. Thermal analysis studies were undertaken and the obtained date show a resemblance of the TG/DTG curves with that found in literature. In the other hand, the DSC curves show a different results: in open crucible, the peaks associated with the cage breakdown are exothermic and, in closed crucible this peaks are endothermic. The thermodecomposition products were analyzed. The evolved gases were identified by GC?MS and 1H and 13 C NMR spectra. The residues were analyzed by X-ray diffraction. Antitumor activity of rhodium cyclopropanecarboxylate was evaluated in vitro (cell cultures K562 and Ehrlich) and in vivo (Balb-c mice with ascite Ehrlich tumor), indicating an increased life span (87.5%) of the treated animals. (author)

  7. Rhodium SPND's Error Reduction using Extended Kalman Filter combined with Time Dependent Neutron Diffusion Equation

    International Nuclear Information System (INIS)

    The Rhodium SPND is accurate in steady-state conditions but responds slowly to changes in neutron flux. The slow response time of Rhodium SPND precludes its direct use for control and protection purposes specially when nuclear power plant is used for load following. To shorten the response time of Rhodium SPND, there were some acceleration methods but they could not reflect neutron flux distribution in reactor core. On the other hands, some methods for core power distribution monitoring could not consider the slow response time of Rhodium SPND and noise effect. In this paper, time dependent neutron diffusion equation is directly used to estimate reactor power distribution and extended Kalman filter method is used to correct neutron flux with Rhodium SPND's and to shorten the response time of them. Extended Kalman filter is effective tool to reduce measurement error of Rhodium SPND's and even simple FDM to solve time dependent neutron diffusion equation can be an effective measure. This method reduces random errors of detectors and can follow reactor power level without cross-section change. It means monitoring system may not calculate cross-section at every time steps and computing time will be shorten. To minimize delay of Rhodium SPND's conversion function h should be evaluated in next study. Neutron and Rh-103 reaction has several decay chains and half-lives over 40 seconds causing delay of detection. Time dependent neutron diffusion equation will be combined with decay chains. Power level and distribution change corresponding movement of control rod will be tested with more complicated reference code as well as xenon effect. With these efforts, final result is expected to be used as a powerful monitoring tool of nuclear reactor core

  8. Rhodium SPND's Error Reduction using Extended Kalman Filter combined with Time Dependent Neutron Diffusion Equation

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jeong Hun; Park, Tong Kyu; Jeon, Seong Su [FNC Technology Co., Ltd., Yongin (Korea, Republic of)

    2014-05-15

    The Rhodium SPND is accurate in steady-state conditions but responds slowly to changes in neutron flux. The slow response time of Rhodium SPND precludes its direct use for control and protection purposes specially when nuclear power plant is used for load following. To shorten the response time of Rhodium SPND, there were some acceleration methods but they could not reflect neutron flux distribution in reactor core. On the other hands, some methods for core power distribution monitoring could not consider the slow response time of Rhodium SPND and noise effect. In this paper, time dependent neutron diffusion equation is directly used to estimate reactor power distribution and extended Kalman filter method is used to correct neutron flux with Rhodium SPND's and to shorten the response time of them. Extended Kalman filter is effective tool to reduce measurement error of Rhodium SPND's and even simple FDM to solve time dependent neutron diffusion equation can be an effective measure. This method reduces random errors of detectors and can follow reactor power level without cross-section change. It means monitoring system may not calculate cross-section at every time steps and computing time will be shorten. To minimize delay of Rhodium SPND's conversion function h should be evaluated in next study. Neutron and Rh-103 reaction has several decay chains and half-lives over 40 seconds causing delay of detection. Time dependent neutron diffusion equation will be combined with decay chains. Power level and distribution change corresponding movement of control rod will be tested with more complicated reference code as well as xenon effect. With these efforts, final result is expected to be used as a powerful monitoring tool of nuclear reactor core.

  9. A novel technique of in situ phase-shift interferometry applied for faint dissolution of bulky montmorillonite in alkaline solution

    International Nuclear Information System (INIS)

    The effect of alkaline pH on the dissolution rate of bulky aggregated montmorillonite samples at 23°C was investigated for the first time by using an enhanced phase-shift interferometry technique combined with an internal refraction interferometry method developed for this study. This technique was applied to provide a molecular resolution during the optical observation of the dissolution phenomena in real time and in situ while remaining noninvasive. A theoretical normal resolution limit of this technique was 0.78 nm in water for opaque material, but was limited to 6.6 nm for montmorillonite due to the transparency of the montmorillonite crystal. Normal dissolution velocities as low as 1 × 10-4 to 1 × 10-3 nm/s were obtained directly by using the measured temporal change in height of montmorillonite samples set in a reaction cell. The molar dissolution fluxes of montmorillonite obtained in this study gave considerably faster dissolution rates in comparison to those obtained in previous investigations by solution analysis methods. The pH dependence of montmorillonite dissolution rate determined in this study was qualitatively in good agreement with those reported in the previous investigations. The dissolution rates to be used in safety assessments of geological repositories for radioactive wastes should be obtained for bulky samples. This goal has been difficult to achieve using conventional powder experiment technique and solution analysis method, but has been shown to be feasible using the enhanced phase-shift interferometry. (author)

  10. Synthesis of graphene oxide-intercalated alpha-hydroxides by metathesis and their decomposition to graphene/metal oxide composites

    OpenAIRE

    Nethravathi, C; Rajamathi, Michael; Ravishankar, N.; Basit, Lubna; FELSER, CLAUDIA

    2010-01-01

    Graphene oxide-intercalated alpha-metal hydroxides were prepared using layers from the delaminated colloidal dispersions of cetyltrimethylammonium-intercalated graphene oxide and dodecylsulfate-intercalated alpha-hydroxide of nickel/cobalt as precursors. The reaction of the two dispersions leads to de-intercalation of the interlayer ions from both the layered solids and the intercalation of the negatively charged graphene oxide sheets between the positively charged layers of the alpha-hydroxi...

  11. All-Carbon [3+3] Oxidative Annulations of 1,3-Enynes by Rhodium(III)-Catalyzed C–H Functionalization and 1,4-Migration**

    Science.gov (United States)

    Burns, David J; Best, Daniel; Wieczysty, Martin D; Lam, Hon Wai

    2015-01-01

    1,3-Enynes containing allylic hydrogens cis to the alkyne function as three-carbon components in rhodium(III)-catalyzed, all-carbon [3+3] oxidative annulations to produce spirodialins. The proposed mechanism of these reactions involves the alkenyl-to-allyl 1,4-rhodium(III) migration. PMID:26224377

  12. Phase Separation Dynamics in Isotropic Ion-Intercalation Particles

    CERN Document Server

    Zeng, Yi

    2013-01-01

    Lithium-ion batteries exhibit complex nonlinear dynamics, resulting from diffusion and phase transformations coupled to ion intercalation reactions. Using the recently developed Cahn-Hilliard reaction (CHR) theory, we investigate a simple mathematical model of ion intercalation in a spherical solid nanoparticle, which predicts transitions from solid-solution radial diffusion to two-phase shrinking-core dynamics. This general approach extends previous Li-ion battery models, which either neglect phase separation or postulate a spherical shrinking-core phase boundary, by predicting phase separation only under appropriate circumstances. The effect of the applied current is captured by generalized Butler-Volmer kinetics, formulated in terms of diffusional chemical potentials, and the model consistently links the evolving concentration profile to the battery voltage. We examine sources of charge/discharge asymmetry, such as asymmetric charge transfer and surface "wetting" by ions within the solid, which can lead to...

  13. Nuclear Magnetic Resonance Study of Fluorine-Graphite Intercalation Compounds

    International Nuclear Information System (INIS)

    To study the origin of semimetal-metal and metal-insulator transformations, localization effects and C-E bonding in fluorine-intercalated graphite CxF, 13C and 19F NMR investigations have been carried out for a wide range of fluorine content, 3.8 8, are attributed to mobile fluorine acceptor species which are responsible for the increase of electric conductivity in the dilute compound. When increasing the fluorine content to x ∼ 8 corresponding to the maximum electric conductivity, covalent C-P bonds start to oc- cur. The number of these bonds grows with fluorine content resulting in the decrease in conductivity which is caused by a percolation mechanism rather than by a change in bond length. A difference in 19F chemical shift for fluorine-intercalated graphite CxF and covalent graphite fluoride (CF)n has been observed and is attributed to different C-P bonding in these compounds

  14. Preparation of polystyrene–clay nanocomposite by solution intercalation technique

    Indian Academy of Sciences (India)

    P K Paul; S A Hussain; D Bhattacharjee; M Pal

    2013-06-01

    Polymer–clay nanocomposites of commercial polystyrene (PS) and clay laponite were prepared via solution intercalation technique. Laponite was modified suitably with the well known cationic surfactant cetyltrimethyl ammonium bromide by ion-exchange reaction to render laponite miscible with hydrophobic PS. X-ray diffraction analysis in combination with scanning electron microscopy gives an idea of structural and morphological information of PS–laponite nanocomposite for different varying organo-laponite contents. Intercalation of PS chain occurs into the interlayer spacings of laponite for low organo-laponite concentration in the PS–O-laponite mixture. However, aggregation and agglomeration occur at higher clay concentration. The molecular bond vibrational profile of laponite as well as PS–laponite nanocomposite have been explored by Fourier transform infrared spectroscopy. Thermogravimetric analysis along with differential scanning calorimetry results reveal the enhancement of both thermal stability and glass transition temperature of PS due to the incorporation of clay platelets.

  15. Controlling the photoconductivity: Graphene oxide and polyaniline self assembled intercalation

    Energy Technology Data Exchange (ETDEWEB)

    Vempati, Sesha, E-mail: svempati01@qub.ac.uk [UNAM-National Nanotechnology Research Centre, Bilkent University, Ankara 06800 (Turkey); Ozcan, Sefika [UNAM-National Nanotechnology Research Centre, Bilkent University, Ankara 06800 (Turkey); Department of Polymer Science and Technology, Middle East Technical University, Ankara 06800 (Turkey); Uyar, Tamer, E-mail: uyar@unam.bilkent.edu.tr [UNAM-National Nanotechnology Research Centre, Bilkent University, Ankara 06800 (Turkey); Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800 (Turkey)

    2015-02-02

    We report on controlling the optoelectronic properties of self-assembled intercalating compound of graphene oxide (GO) and HCl doped polyaniline (PANI). Optical emission and X-ray diffraction studies revealed a secondary doping phenomenon of PANI with –OH and –COOH groups of GO, which essentially arbitrate the intercalation. A control on the polarity and the magnitude of the photoresponse (PR) is harnessed by manipulating the weight ratios of PANI to GO (viz., 1:1.5 and 1:2.2 are abbreviated as PG1.5 and PG2.2, respectively), where ±PR = 100(R{sub Dark} – R{sub UV-Vis})/R{sub Dark} and R corresponds to the resistance of the device in dark or UV-Vis illumination. To be precise, the PR from GO, PANI, PG1.5, and PG2.2 are +34%, −111%, −51%, and +58%, respectively.

  16. Intercalated graphite fiber composites as EMI shields in aerospace structures

    Science.gov (United States)

    Gaier, James R.

    1992-01-01

    The requirements for electromagnetic interference (EMI) shielding in aerospace structures are more complicated than those for ground structures because of their weight limitations. As a result, the best EMI shielding materials must combine low density, high strength, and high elastic modulus with high shielding ability. EMI shielding characteristics were calculated for shields formed from pristine and intercalated graphite fiber/epoxy composites and compare to preliminary experimental results for these materials and to the characteristics of shields made from aluminum. Calculations indicate that effective EMI shields could be fabricated from intercalated graphite composites which would have less than 12 percent of the mass of conventional aluminum shields, based on mechanical properties and shielding characteristics alone.

  17. Induced magnetism in transition metal intercalated graphitic systems

    KAUST Repository

    Kaloni, Thaneshwor P.

    2011-10-26

    We investigate the structure, chemical bonding, electronic properties, and magnetic behavior of a three-dimensional graphitic network in aba and aaa stacking with intercalated transition metal atoms (Mn, Fe, Co, Ni, and Cu). Using density functional theory, we find induced spin-polarization of the C atoms both when the graphene sheets are aba stacked (forming graphite) and aaa stacked (resembling bi-layer graphene). The magnetic moment induced by Mn, Fe, and Co turns out to vary from 1.38 μB to 4.10 μB, whereas intercalation of Ni and Cu does not lead to a magnetic state. The selective induction of spin-polarization can be utilized in spintronic and nanoelectronic applications.

  18. May bis-intercalator-peptides influence prion aggregation?

    Czech Academy of Sciences Publication Activity Database

    Šebestík, Jaroslav; Hlaváček, Jan; Stibor, I.

    Praha: ÚOCHB AV ČR, 2003 - (Slaninová, J.), s. 98-101 ISBN 80-86241-20-3. [Biologically Active Peptides /8./. Praha (CZ), 23.04.2003-25.04.2003] R&D Projects: GA ČR GA203/02/1379 Institutional research plan: CEZ:AV0Z4055905 Keywords : prion * DNA * bis-intercalators Subject RIV: CC - Organic Chemistry

  19. Intercalation of quaternary ammonium epoxide into montmorillonite structure

    Czech Academy of Sciences Publication Activity Database

    Duchek, P.; Špírková, Milena; Šabata, Stanislav

    Beijing : Chinese Vacuum Society, 2010. s. 109. [International Vacuum Congress /18./, International Conference on Nanoscience and Technology, International Conference on Solid Surfaces /14./, Vacuum and Surface Sciences Conference of Asia and Australia. 23.08.2010-27.08.2010, Beijing] R&D Projects: GA AV ČR(CZ) IAAX08240901 Institutional research plan: CEZ:AV0Z40500505; CEZ:AV0Z40720504 Keywords : montmorillonite * quaternary ammonium epoxide * intercalation Subject RIV: JI - Composite Materials

  20. Preferential Intercalation of Pyridinedicarboxylates into Layered Double Hydroxides

    Institute of Scientific and Technical Information of China (English)

    李蕾; 莫丹; 陈大舟

    2005-01-01

    Intercalation of 2,3-,2,4-,2,5-,2,6-,3,4-,or3,5-pyridincdicarboxylate into the layered double hydroxide (LDH),[Mg0.73AIo.27(OH)2](CO3)0.14*1.34H2O was carried out by the reconstruction method in the molar ratio of organic acid: calcined LDH=3:8, in 80% alcoholic aqueous solution at 70℃. Selective reaction was observed in com-petitive experiments involving an equal concentration pairs of acids. The preference order of the organic acids intercalated into the Mg-Al-LDH was found to be in the order of 2,3-pyridinedicarboxylate>2,5-pyridinedicarboxylate>2,4-pyridinedicarboxylate>3,5-pyridinedicarboxylate>3,4-pyridinedicarboxylate>2,6-pyridinedic arboxylate. The structures of the intercalates formed by the reaction of six guests with Mg-Al-LDH were characterized by X-ray diffraction, infrared and thermogravimetry techniques. And the charge density on the oxygens of each of the carboxylate groups for the six anions was investigated utilizing ab initio (HF/6-31G) method by G98w. From the X-ray diffraction data, the guest size and the charge density of the oxygens of the guest, the orientation of 2,3-,2,4-,2,5-,2,6-,3,4-, or 3,5-pyridinedicarboxylate anions between the layers was determined and the preferential intercalation mechanism was discussed. These results indicate the possibility of a molecular recognition ability of LDH and it would be exploited for the chemical separation of some anions from solution.

  1. Intercalation of Epinephrine with Calf-thymus ds-DNA

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A strong interaction between double stranded calf-thymus DNA (ds-DNA) and epinephrine but no interaction between single stranded calf-thymus DNA (ss-DNA) and epinephrine were observed by the use of UV-spectroscopy and cyclic voltammetry. It is suggested that the interaction leads to an intercalation of EP molecules into the groove of ds-DNA and the formation of ds-DNA(EP)n complex.

  2. Graphene Made by Mechanical Exfoliation of Graphite Intercalation Compound

    Science.gov (United States)

    Fukada, Seiya; Shintani, Yumi; Shimomura, Midori; Tahara, Fumiya; Yagi, Ryuta

    2012-08-01

    We report a method of making few-layer graphene flakes by mechanically exfoliating SbCl5-graphite intercalation compounds (GICs). The number of layers of exfoliated graphene flakes had a particular distribution relevant to the stage structure of the GICs. The carrier doping of the few-layer graphene flakes was about two orders of magnitude smaller than that expected from the stoichiometry of the GICs. The measured electric mobility was comparable to that made from pristine graphite.

  3. Sodium-Ion Intercalation Mechanism in MXene Nanosheets.

    Science.gov (United States)

    Kajiyama, Satoshi; Szabova, Lucie; Sodeyama, Keitaro; Iinuma, Hiroki; Morita, Ryohei; Gotoh, Kazuma; Tateyama, Yoshitaka; Okubo, Masashi; Yamada, Atsuo

    2016-03-22

    MXene, a family of layered compounds consisting of nanosheets, is emerging as an electrode material for various electrochemical energy storage devices including supercapacitors, lithium-ion batteries, and sodium-ion batteries. However, the mechanism of its electrochemical reaction is not yet fully understood. Herein, using solid-state (23)Na magic angle spinning NMR and density functional theory calculation, we reveal that MXene Ti3C2Tx in a nonaqueous Na(+) electrolyte exhibits reversible Na(+) intercalation/deintercalation into the interlayer space. Detailed analyses demonstrate that Ti3C2Tx undergoes expansion of the interlayer distance during the first sodiation, whereby desolvated Na(+) is intercalated/deintercalated reversibly. The interlayer distance is maintained during the whole sodiation/desodiation process due to the pillaring effect of trapped Na(+) and the swelling effect of penetrated solvent molecules between the Ti3C2Tx sheets. Since Na(+) intercalation/deintercalation during the electrochemical reaction is not accompanied by any substantial structural change, Ti3C2Tx shows good capacity retention over 100 cycles as well as excellent rate capability. PMID:26891421

  4. Crystal structures of superconducting sodium intercalates of hafnium nitride chloride

    International Nuclear Information System (INIS)

    Sodium intercalation compounds of HfNCl have been prepared at room temperature in naphtyl sodium solutions in tetrahydrofuran and their crystal structure has been investigated by Rietveld refinement using X-ray powder diffraction data and high-resolution electron microscopy. The structure of two intercalates with space group R3-bar m and lattice parameters a=3.58131(6)A, c=57.752(6)A, and a=3.58791(8)A, c=29.6785(17)A is reported, corresponding to the stages 2 and 1, respectively, of NaxHfNCl. For the stage 2 phase an ordered model is presented, showing two crystallographically independent [HfNCl] units with an alternation of the Hf-Hf interlayer distance along the c-axis, according with the occupation by sodium atoms of one out of two van der Waals gaps. Both stages 1 and 2 phases are superconducting with critical temperatures between 20 and 24K, they coexist in different samples with proportions depending on the synthesis conditions, and show a variation in c spacing that can be correlated with the sodium stoichiometry. High-resolution electron microscopy images of the host and intercalated samples show bending of the HfNCl bilayers as well as stacking faults in some regions, which coexist in the same crystal with ordered domains

  5. Phase separation in lithium intercalated anatase: A theory

    Directory of Open Access Journals (Sweden)

    O.V. Velychko

    2009-01-01

    Full Text Available Lithium intercalated anatase used in Li-ion batteries has some special features: coexistence of Li-rich and Li-poor phases as well as two possible positions for Li ions in the oxygen tetrahedron. A theoretical description of the compound considering those peculiarities is presented. As shown by the performed symmetry analysis, the intercalation induced lattice deformation can be accompanied by the ordering of antiferroelectric type (internal piezoeffect. In the following step, a qualitative illustration of the phase separation in the lithiated anatase is given within the Landau expansion at the proper choice of coefficients. A microscopic model for description of the compound is also proposed which combines features of the Mitsui and Blume-Emery-Griffits models and utilizes the symmetry analysis results. Various ground state and temperature-dependent phase diagrams of the model are studied to find a set of model parameters corresponding to the lithiated anatase. A phase separation into the empty and half-filled phases in a wide temperature range has been found closely resembling the phase coexistence in the intercalated crystal. In the framework of the model, the two-position Li subsystem could have the ordering of ferro- or antiferroelectric types which, however, has not been yet observed by the experiment.

  6. Molecular Intercalation and Cohesion of Organic Bulk Heterojunction Photovoltaic Devices

    KAUST Repository

    Bruner, Christopher

    2013-01-17

    The phase separated bulk heterojunction (BHJ) layer in BHJ polymer:fullerene organic photovoltaic devices (OPV) are mechanically weak with low values of cohesion. Improved cohesion is important for OPV device thermomechanical reliability. BHJ devices are investigated and how fullerene intercalation within the active layer affects cohesive properties in the BHJ is shown. The intercalation of fullerenes between the side chains of the polymers poly(3,3″′-didocecyl quaterthiophene) (PQT-12) and poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene (pBTTT) is shown to enhance BHJ layer cohesion. Cohesion values range from ≈1 to 5 J m -2, depending on the polymer:fullerene blend, processing conditions, and composition. Devices with non-intercalated BHJ layers are found to have significantly reduced values of cohesion. The resulting device power conversion efficiencies (PCE) are also investigated and correlated with the device cohesion. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Electroplating/electrodissolution/recovery cycle for rhodium target used for an industrial scale cyclotron production of palladium-103

    International Nuclear Information System (INIS)

    Electrodeposition of rhodium metal on a copper backing was performed in acidic sulfate media using RhCl3 . 3 H2O, Rh2(SO4)3 (recovered from hydrochloric acid solution) and also the commercially available Rhodex plating baths. This work describes the development of a high current density (2.4 A.cm-2) electrodissolution system that allows solubilisation of rhodium fragments, powder and pieces of foils and wires in the presence of hydrochloric and chlorine gas. Solvent-solvent extraction of no-carrier-added 103Pd from the irradiated rhodium target with a-furyldioxime into chloroform under the influence of hydrochloric acid concentration was investigated. The extraction yield was 85.3% for a single extraction with 0.37 M HCl. and 103Pd was more than 99% pure. (orig.)

  8. A rhodium/silicon co-electrocatalyst design concept to surpass platinum hydrogen evolution activity at high overpotentials.

    Science.gov (United States)

    Zhu, Lili; Lin, Haiping; Li, Youyong; Liao, Fan; Lifshitz, Yeshayahu; Sheng, Minqi; Lee, Shuit-Tong; Shao, Mingwang

    2016-01-01

    Currently, platinum-based electrocatalysts show the best performance for hydrogen evolution. All hydrogen evolution reaction catalysts should however obey Sabatier's principle, that is, the adsorption energy of hydrogen to the catalyst surface should be neither too high nor too low to balance between hydrogen adsorption and desorption. To overcome the limitation of this principle, here we choose a composite (rhodium/silicon nanowire) catalyst, in which hydrogen adsorption occurs on rhodium with a large adsorption energy while hydrogen evolution occurs on silicon with a small adsorption energy. We show that the composite is stable with better hydrogen evolution activity than rhodium nanoparticles and even exceeding those of commercial platinum/carbon at high overpotentials. The results reveal that silicon plays a key role in the electrocatalysis. This work may thus open the door for the design and fabrication of electrocatalysts for high-efficiency electric energy to hydrogen energy conversion. PMID:27447292

  9. Ge-intercalated graphene: The origin of the p-type to n-type transition

    KAUST Repository

    Kaloni, Thaneshwor P.

    2012-09-01

    Recently huge interest has been focussed on Ge-intercalated graphene. In order to address the effect of Ge on the electronic structure, we study Ge-intercalated free-standing C 6 and C 8 bilayer graphene, bulk C 6Ge and C 8Ge, as well as Ge-intercalated graphene on a SiC(0001) substrate, by density functional theory. In the presence of SiC(0001), there are three ways to obtain n-type graphene: i) intercalation between C layers; ii) intercalation at the interface to the substrate in combination with Ge deposition on the surface; and iii) cluster intercalation. All other configurations under study result in p-type states irrespective of the Ge coverage. We explain the origin of the different doping states and establish the conditions under which a transition occurs. © Copyright EPLA, 2012.

  10. Structural Basis for Bulky-Adduct DNA-Lesion Recognition by the Nucleotide Excision Repair Protein Rad14.

    Science.gov (United States)

    Simon, Nina; Ebert, Charlotte; Schneider, Sabine

    2016-07-25

    Heterocyclic aromatic amines react with purine bases and result in bulky DNA adducts that cause mutations. Such structurally diverse lesions are substrates for the nucleotide excision repair (NER). It is thought that the NER machinery recognises and verifies distorted DNA conformations, also involving the xeroderma pigmentosum group A and C proteins (XPA, XPC) that act as a scaffold between the DNA substrate and several other NER proteins. Here we present the synthesis of DNA molecules containing the polycyclic, aromatic amine C8-guanine lesions acetylaminophenyl, acetylaminonaphthyl, acetylaminoanthryl, and acetylaminopyrenyl, as well as their crystal structures in complex with the yeast XPA homologue Rad14. This work further substantiates the indirect lesion-detection mechanism employed by the NER system that recognises destabilised and deformable DNA structures. PMID:27223336

  11. Synthesis and characterization of novel polyamide-ethers based on bis-imidazole containing bulky aryl pendant groups

    Directory of Open Access Journals (Sweden)

    Seyed Mahdi Saadati

    2013-01-01

    Full Text Available A series of novel polyamide-ethers (PAEs based on bis-imidazole containing bulky aryl pendant groups was prepared by direct polycondensation of a diamine, 4-(1-(4-(4-(2-(4-aminophenyl-4,5-diphenyl-1H-imidazol-1-ylphenoxyphenyl-4,5-diphenyl-1H-imidazol-2-ylbenzenamine (DABI, and various dicarboxylic acids. All the resulting polyamide-ethers were amorphous with inherent viscosities ranged from 0.52 to 0.61 dL/g and were readily soluble in many organic solvents which could be solution-cast into transparent and tough films. The glass transition temperatures (Tg of these polymers were affected considerably by their chemical structure and ranged from 230 to 310 ºC. They had useful levels of thermal stability associated with relatively high temperatures of 10% weight loss (T10 in the range of 329-399 ºC in air atmosphere.

  12. Increased micronuclei and bulky DNA adducts in cord blood after maternal exposures to traffic-related air pollution

    DEFF Research Database (Denmark)

    Pedersen, M.; Wichmann, J.; Autrup, H.;

    2009-01-01

    highest among mother-newborn pairs who lived near medium-traffic-density (> 400-2500 vehicle km/24 h; p <0.01) places. MN frequencies among newborns from women who lived at high-traffic-density homes ( > 2500 vehicle km/24 h) were significantly increased (p = 0.02). This trend remained after adjusting for......Exposure to traffic-related air pollution in urban environment is common and has been associated with adverse human health effects. In utero exposures that result in DNA damage may affect health later in life. Early effects of maternal and in utero exposures to traffic-related air pollution were...... assessed through the use of validated biomarkers in blood cells from mother-newborn pairs. A cross-sectional biomonitoring study with healthy pregnant women living in the Greater Copenhagen area, Denmark, was conducted. Bulky DNA adducts and micronuclei (MN) were measured in blood from 75 women and 69...

  13. Van der Waals density functional study of the energetics of alkali metal intercalation in graphite

    OpenAIRE

    Wang, Zhaohui; Selbach, Sverre Magnus; Grande, Tor

    2014-01-01

    We report on the energetics of intercalation of lithium, sodium and potassium in graphite by density functional theory using recently developed van der Waals (vdW) density functionals. First stage intercalation compounds are well described by conventional functionals like GGA, but van der Waals functionals are crucial for higher stage intercalation compounds and graphite, where van der Waals interactions are important. The vdW-optPBE functional gave the best agreement with reported structure ...

  14. Interlayer Structure of Bioactive Molecule, 2-Aminoethanesulfonate, Intercalated into Calcium-Containing Layered Double Hydroxides

    OpenAIRE

    Tae-Hyun Kim; Hyoung Jun Kim; Jae-Min Oh

    2012-01-01

    We have successfully intercalated 2-aminoethanesulfonate, a well-known biomolecule taurine, into calcium-containing layered double hydroxides via optimized solid phase intercalation. According to X-ray diffraction patterns and infrared spectroscopy, it was revealed that the intercalated taurine molecules were each directly coordinated to other calcium cation and arranged in a zig-zag pattern. Scanning electron microscopy showed that the particle size and morphology of the LDHs were not affect...

  15. Linkage structures strongly influence the binding cooperativity of DNA intercalators conjugated to triplex forming oligonucleotides.

    OpenAIRE

    1994-01-01

    Conjugation of DNA intercalators to triple helix forming oligodeoxynucleotides (ODN's) can enhance ODN binding properties and consequently their potential ability to modulate gene expression. To test the hypothesis that linkage structure could strongly influence the binding enhancement of intercalator conjugation with triplex forming ODN's, we have used a model system to investigate binding avidity of short oligomers conjugated to DNA intercalators through various linkages. Using a dA10.T10 t...

  16. Bi_2WO_6 quantum dot-intercalated ultrathin montmorillonite nanostructure and its enhanced photocatalytic performance

    OpenAIRE

    Sun, Songmei; WANG, WENZHONG; Jiang, Dong; Zhang, Ling; Li, Xiaoman; Yali, Zheng; An, Qi

    2014-01-01

    The kinetic competition between electron-hole recombination and water oxidation is a key limitation for the development of efficient solar water splitting materials. In this study, we present a solution for solving this challenge by constructing a quantum dot-intercalated nanostructure. For the first time, we show the interlayer charge of the intercalated nanostructure can significantly inhibit the electron-hole recombination in photocatalysis. For Bi_2WO_6 quantum dots (QDs) intercalated in ...

  17. Preparation of Fe-intercalated Graphite Based on Coal Tailings, Dimensional Structure

    OpenAIRE

    Irfan Gustian; Eka Angasa; Dwi Agustini; Evi Maryanti; Dyiah Fitriani

    2015-01-01

    Intercalated graphite from coal tailings have been modified through the intercalation of iron. Coal tailings which is a byproduct of the destruction process and flakes washing results from mining coal. Intercalation of iron goal is to improve the physical properties of graphite and modifying sizes of crystal lattice structure with thermal method. Modification process begins with the carbonization of coal tailings at 500ºC and activated with phosphoric acid. Activation process has done by pyro...

  18. Effect of temperature on adsorption of hydrogen by catalysts of ruthenium-rhodium system in sulfuric acid solutions

    International Nuclear Information System (INIS)

    Temperature dependence has been studied of hydrogen adsorption on sceletal ruthenium-rhodium catalysts in 1 N solution of sulfuric acid in a temperature range 20-80 deg C at 20 deg C intervals. The conditions and the results of preliminary stabilization of the catalysts are described. It has been established that hydrogen adsorption on sceletal ruthenium and rhodium-ruthenium catalysts decreases with a temperature rise in the above-cited range. The temperature dependence of hydrogen adsorption has been used for plotting adsorption isotherms and for determining isosterical differential heats of hydrogen adsorption and bond energy of hydrogen with the surface

  19. Moessbauer spectroscopic characterisation of catalysts obtained by interaction between tetra-n-butyl-tin and silica or silica supported rhodium

    International Nuclear Information System (INIS)

    Moessbauer spectroscopy at 78 K was used to study the interaction between tetra-n-butyl-tin and the surfaces of silica or silica supported rhodium. At room temperature, the tetra-n-butyl-tin was physically adsorbed on the surfaces. After reaction under hydrogen at 373 K, the formation of grafted organometallic fragments on the Rh surface was confirmed whereas with pure silica, ≡SiO-Sn(n-C4H9)3 moieties were observed. After treatment at 523 K, the rhodium grafted organometallic species was completely decomposed and there was formation of a defined bimetallic RhSn compound

  20. Catalytic hydrogen evolution from water by reduced forms of 12-tungstosilicic acid in the presence of heterogeneous rhodium polymeric catalysts

    International Nuclear Information System (INIS)

    Catalytic effect of heterogeneous rhodium-polymeric catalyst on the hydrogen evolution from aqueous and aqueous-alcohol solutions of slightly reduced forms of 12-tungstosilic acid has been studied. The activity of the catalyst studied under experimental conditions is limited by the reagent diffusion from the solution volume. It is found, that heteropolyacid ions, immobilized on the polymer together with fine-dispersed particles of metallic rhodium, take active part in the electron transfer from the solution volume onto metallic particles inside a polymeric carriei thus promoting the catalytic process

  1. Enantioselective Rhodium(I) Donor Carbenoid-Mediated Cascade Triggered by a Base-Free Decomposition of Arylsulfonyl Hydrazones.

    Science.gov (United States)

    Torres, Òscar; Parella, Teodor; Solà, Miquel; Roglans, Anna; Pla-Quintana, Anna

    2015-11-01

    The reaction of diyne arylsulfonyl hydrazone substrates under rhodium(I)/BINAP catalysis gives access to sulfonated azacyclic frameworks in a highly enantioselective manner. This new cascade process considerably increases the molecular complexity by generating two C-C bonds, one C-S bond, and one C-H bond. Theoretical calculations, competitive experiments, and deuterium labeling have jointly been used to propose a mechanism that accounts for the reaction. The mechanism involves the formation of vinyl rhodium carbenoids, hydride migratory insertion, and intermolecular stereoselective nucleophilic attack. The last two steps are the key to the stereoselectivity of the process. PMID:26397988

  2. Oxidation of rhodium (3) by periodate in alkali medium and chemiluminescent catalytic reaction of luminol with periodate in the presence of rhodium (3)

    International Nuclear Information System (INIS)

    A new reaction of oxidation of Rh (3) chloride by a periodate to Rh (5) has been found to take place in an alkaline medium. Oxidation of luminol by the compound Rh (5) is chemiluminescent. These reactions proceed at a considerable rate. Catalytic action of Rh (3) in the chemiluminescent reaction of luminol with the periodate includes the above reactions with the redox cycle Rh (3) reversible Rh (5). The reaction of oxidation of Rh (3) by the periodate can be used for photometric determination of 20-100 μkg of rhodium in 5 ml of a finite volume as a violent colour compound Rh (5) with the absorption maximum at lambda 600 nm. Time of full colour development is 8-10 min without heating the solutions; colour stability is 16 hrs

  3. Potential Modulated Intercalation of Alkali Cations into Metal Hexacyanoferrate Coated Electrodes

    International Nuclear Information System (INIS)

    Nickel hexacyanoferrate is a polynuclear inorganic ion intercalation material that loads (intercalates) and elutes (deintercalates) alkali cations from its structure when electrochemically reduced and oxidized, respectively. Nickel hexacyanoferrrate (NiHCF) is known to preferentially intercalate cesium over all other alkali cations, thus providing a basis for a separation scheme that can tackle DOE's radiocesium contamination problem. This program studied fundamental issues in alkalization intercalation and deintercalation in nickel hexacyanoferrate compounds, with the goal of (1) quantifying the ion exchange selectivity properties from cation mixtures, (2) enhancing ion exchange capacities, and (3) and understanding the electrochemically-switched ion exchange process (ESIX)

  4. Tuning the Properties of Polymer Bulk Heterojunction Solar Cells by Adjusting Fullerene Size to Control Intercalation

    KAUST Repository

    Cates, Nichole C.

    2009-12-09

    We demonstrate that intercalation of fullerene derivatives between the side chains of conjugated polymers can be controlled by adjusting the fullerene size and compare the properties of intercalated and nonintercalated poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene (pBTTT):fullerene blends. The intercalated blends, which exhibit optimal solar-cell performance at 1:4 polymer:fullerene by weight, have better photoluminescence quenching and lower absorption than the nonintercalated blends, which optimize at 1:1. Understanding how intercalation affects performance will enable more effective design of polymer:fullerene solar cells. © 2009 American Chemical Society.

  5. Mechanism of Si intercalation in defective graphene on SiC

    KAUST Repository

    Kaloni, Thaneshwor P.

    2012-10-01

    Previously reported experimental findings on Si-intercalated graphene on SiC(0001) seem to indicate the possibility of an intercalation process based on the migration of the intercalant through atomic defects in the graphene sheet. We employ density functional theory to show that such a process is in fact feasible and obtain insight into its details. By means of total energy and nudged elastic band calculations we are able to establish the mechanism on an atomic level and to determine the driving forces involved in the different steps of the intercalation process through atomic defects.

  6. Structure and thermal decomposition of sulfated β-cyclodextrin intercalated in a layered double hydroxide

    International Nuclear Information System (INIS)

    The sodium salt of hexasulfated β-cyclodextrin has been synthesized and intercalated into a magnesium-aluminum layered double hydroxide by ion exchange. The structure, composition and thermal decomposition behavior of the intercalated material have been studied by variable temperature X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), inductively coupled plasma emission spectroscopy (ICP), and thermal analysis (TG-DTA) and a model for the structure has been proposed. The thermal stability of the intercalated sulfated β-cyclodextrin is significantly enhanced compared with the pure form before intercalation

  7. Intrinsic Selectivity and Structure Sensitivity of Rhodium Catalysts for C(2+) Oxygenate Production.

    Science.gov (United States)

    Yang, Nuoya; Medford, Andrew J; Liu, Xinyan; Studt, Felix; Bligaard, Thomas; Bent, Stacey F; Nørskov, Jens K

    2016-03-23

    Synthesis gas (CO + H2) conversion is a promising route to converting coal, natural gas, or biomass into synthetic liquid fuels. Rhodium has long been studied as it is the only elemental catalyst that has demonstrated selectivity to ethanol and other C2+ oxygenates. However, the fundamentals of syngas conversion over rhodium are still debated. In this work a microkinetic model is developed for conversion of CO and H2 into methane, ethanol, and acetaldehyde on the Rh (211) and (111) surfaces, chosen to describe steps and close-packed facets on catalyst particles. The model is based on DFT calculations using the BEEF-vdW functional. The mean-field kinetic model includes lateral adsorbate-adsorbate interactions, and the BEEF-vdW error estimation ensemble is used to propagate error from the DFT calculations to the predicted rates. The model shows the Rh(211) surface to be ∼6 orders of magnitude more active than the Rh(111) surface, but highly selective toward methane, while the Rh(111) surface is intrinsically selective toward acetaldehyde. A variety of Rh/SiO2 catalysts are synthesized, tested for catalytic oxygenate production, and characterized using TEM. The experimental results indicate that the Rh(111) surface is intrinsically selective toward acetaldehyde, and a strong inverse correlation between catalytic activity and oxygenate selectivity is observed. Furthermore, iron impurities are shown to play a key role in modulating the selectivity of Rh/SiO2 catalysts toward ethanol. The experimental observations are consistent with the structure-sensitivity predicted from theory. This work provides an improved atomic-scale understanding and new insight into the mechanism, active site, and intrinsic selectivity of syngas conversion over rhodium catalysts and may also guide rational design of alloy catalysts made from more abundant elements. PMID:26958997

  8. Permeation of platinum and rhodium nanoparticles through intact and damaged human skin

    International Nuclear Information System (INIS)

    The aim of the study was to evaluate percutaneous penetration of platinum and rhodium nanoparticles (PtNPs: 5.8 ± 0.9 nm, RhNPs: 5.3 ± 1.9 nm) through human skin. Salts compounds of these metals are sensitizers and some also carcinogenic agents. In vitro permeation experiments were performed using Franz diffusion cells with intact and damaged skin. PtNPs and RhNPs, stabilized with polyvinylpyrrolidone, were synthesized by reduction of Na2PtCl6 and RhCl3·3H2O respectively. Suspensions with a concentration of 2.0 g/L of PtNPs and RhNPs were dispersed separately in synthetic sweat at pH 4.5 and applied as donor phases to the outer surface of the skin for 24 h. Measurements of the content of the metals in the receiving solution and in the skin were performed subsequently. Rhodium skin permeation was demonstrated through damaged skin, with a permeation flux of 0.04 ± 0.04 μg cm−2 h−1 and a lag time of 7.9 ± 1.1 h, while no traces of platinum were found in receiving solutions. Platinum and rhodium skin-analysis showed significantly higher concentrations of the metals in damaged skin. Rh and Pt applied as NPs can penetrate the skin barrier and Rh can be found in receiving solutions. These experiments pointed out the need for skin contamination prevention, since even a minor injury to the skin barrier can significantly increase penetration

  9. Permeation of platinum and rhodium nanoparticles through intact and damaged human skin

    Energy Technology Data Exchange (ETDEWEB)

    Mauro, Marcella [University of Trieste, Clinical Unit of Occupational Medicine, Department of Medical Sciences (Italy); Crosera, Matteo; Bianco, Carlotta; Adami, Gianpiero; Montini, Tiziano; Fornasiero, Paolo [University of Trieste, Department of Chemical and Pharmaceutical Sciences (Italy); Jaganjac, Morana [Rudjer Boskovic Institute, Laboratory for Oxidative Stress, Department of Molecular Medicine (Croatia); Bovenzi, Massimo; Filon, Francesca Larese, E-mail: larese@units.it [University of Trieste, Clinical Unit of Occupational Medicine, Department of Medical Sciences (Italy)

    2015-06-15

    The aim of the study was to evaluate percutaneous penetration of platinum and rhodium nanoparticles (PtNPs: 5.8 ± 0.9 nm, RhNPs: 5.3 ± 1.9 nm) through human skin. Salts compounds of these metals are sensitizers and some also carcinogenic agents. In vitro permeation experiments were performed using Franz diffusion cells with intact and damaged skin. PtNPs and RhNPs, stabilized with polyvinylpyrrolidone, were synthesized by reduction of Na{sub 2}PtC{sub l6} and RhCl{sub 3}·3H{sub 2}O respectively. Suspensions with a concentration of 2.0 g/L of PtNPs and RhNPs were dispersed separately in synthetic sweat at pH 4.5 and applied as donor phases to the outer surface of the skin for 24 h. Measurements of the content of the metals in the receiving solution and in the skin were performed subsequently. Rhodium skin permeation was demonstrated through damaged skin, with a permeation flux of 0.04 ± 0.04 μg cm{sup −2} h{sup −1} and a lag time of 7.9 ± 1.1 h, while no traces of platinum were found in receiving solutions. Platinum and rhodium skin-analysis showed significantly higher concentrations of the metals in damaged skin. Rh and Pt applied as NPs can penetrate the skin barrier and Rh can be found in receiving solutions. These experiments pointed out the need for skin contamination prevention, since even a minor injury to the skin barrier can significantly increase penetration.

  10. Rhodium Porphyrin Bound to a Merrifield Resin as Heterogeneous Catalyst for the Cyclopropanation Reaction of Olefins.

    Science.gov (United States)

    Ciammaichella, Alina; Cardoni, Valeria; Leoni, Alessandro; Tagliatesta, Pietro

    2016-01-01

    Cyclopropanation reaction is an important tool for obtaining interesting compounds and can be catalyzed by metalloporphyrins with high syn/anti ratio. The catalyst cannot be recycled and is usually lost during chromatographic separation from the two isomeric products. In this paper a meso-tetraphenylporphyrin rhodium(III) chloride was bound to a Merrifield resin and used to catalyze the cyclopropanation reaction of nine olefins, giving good yields and selectivities of the final products and for the first time, a partial recycling of the catalyst. This new catalytic system will be tested in the future for the synthesis of natural products containing cyclopropyl ring. PMID:26927056

  11. Rhodium in-core detector sensitivity depletion, cycles 2-5

    International Nuclear Information System (INIS)

    Sensitivity depletion of two rhodium (Rh) self-powered neutron detectors (SPNDs) has been measured since July 1976 at the Oconee 2 pressurized water reactor (PWR). The detectors were positioned inside the reactor core throughout the measurement period. Depletion has been determined as a function of electric charge released by each detector. The goal of the project is the empirical definition of the depletion characteristics over the operating life-time of the Rh detector. Results to date show that the sensitivity depletion rate of the Rh detector in the PWR is highly linear with charge released from the detector

  12. Hydrolysis of Letrozole catalyzed by macrocyclic Rhodium (I) Schiff-base complexes

    Science.gov (United States)

    Reddy, P. Muralidhar; Shanker, K.; Srinivas, V.; Krishna, E. Ravi; Rohini, R.; Srikanth, G.; Hu, Anren; Ravinder, V.

    2015-03-01

    Ten mononuclear Rhodium (I) complexes were synthesized by macrocyclic ligands having N4 and N2O2 donor sites. Square planar geometry is assigned based on the analytical and spectral properties for all complexes. Rh(I) complexes were investigated as catalysts in hydrolysis of Nitrile group containing pharmaceutical drug Letrozole. A comparative study showed that all the complexes are efficient in the catalysis. The percent yields of all the catalytic reaction products viz. drug impurities were determined by spectrophotometric procedures and characterized by spectral studies.

  13. Rhodium-Catalyzed Stitching Reaction: Convergent Synthesis of Quinoidal Fused Oligosiloles.

    Science.gov (United States)

    Shintani, Ryo; Iino, Ryo; Nozaki, Kyoko

    2016-03-23

    Quinoidal fused oligosiloles, a new family of silicon-bridged π-conjugated compounds, have been synthesized for the first time based on a new synthetic strategy, a stitching reaction. Multiple carbon-carbon bonds can be formed consecutively between two oligo(silylene-ethynylene)s under rhodium catalysis in a stitching manner, and up to five siloles have been fused in a quinoidal form. Physical properties of these oligosiloles have also been investigated to find a unique trend in their LUMO levels, which become higher with longer π-conjugation. PMID:26961329

  14. Chiral P,N-bidentate ligands in coordination chemistry and organic catalysis involving rhodium and palladium

    International Nuclear Information System (INIS)

    Published data on the synthesis of rhodium and palladium complexes with optically active P,N-bidentate ligands and their applications in homogeneous asymmetric catalysis are summarised and discussed. The effect of the nature of the P,N-bidentate compounds on the structure of the metal complexes and on enantioselectivity in catalysis is examined. Allylic substitution, cross-coupling, hydroboration and hydrosilylation catalysed by Rh or Pd complexes with optically active P,N-bidentate ligands are considered. The prospects for the development of this field of chemistry are demonstrated. The bibliography includes 186 references.

  15. Screen-Printed Carbon Electrodes Modified by Rhodium Dioxide and Glucose Dehydrogenase

    OpenAIRE

    Vojtěch Polan; Jan Soukup; Karel Vytřas

    2011-01-01

    The described glucose biosensor is based on a screen-printed carbon electrode (SPCE) modified by rhodium dioxide, which functions as a mediator. The electrode is further modified by the enzyme glucose dehydrogenase, which is immobilized on the electrode's surface through electropolymerization with m-phenylenediamine. The enzyme biosensor was optimized and tested in model glucose samples. The biosensor showed a linear range of 500–5000 mg L−1 of glucose with a detection limit of 210 mg L−1 (es...

  16. The intercalated nuclear complex of the primate amygdala.

    Science.gov (United States)

    Zikopoulos, Basilis; John, Yohan J; García-Cabezas, Miguel Ángel; Bunce, Jamie G; Barbas, Helen

    2016-08-25

    The organization of the inhibitory intercalated cell masses (IM) of the primate amygdala is largely unknown despite their key role in emotional processes. We studied the structural, topographic, neurochemical and intrinsic connectional features of IM neurons in the rhesus monkey brain. We found that the intercalated neurons are not confined to discrete cell clusters, but form a neuronal net that is interposed between the basal nuclei and extends to the dorsally located anterior, central, and medial nuclei of the amygdala. Unlike the IM in rodents, which are prominent in the anterior half of the amygdala, the primate inhibitory net stretched throughout the antero-posterior axis of the amygdala, and was most prominent in the central and posterior extent of the amygdala. There were two morphologic types of intercalated neurons: spiny and aspiny. Spiny neurons were the most abundant; their somata were small or medium size, round or elongated, and their dendritic trees were round or bipolar, depending on location. The aspiny neurons were on average slightly larger and had varicose dendrites with no spines. There were three non-overlapping neurochemical populations of IM neurons, in descending order of abundance: (1) Spiny neurons that were positive for the striatal associated dopamine- and cAMP-regulated phosphoprotein (DARPP-32+); (2) Aspiny neurons that expressed the calcium-binding protein calbindin (CB+); and (3) Aspiny neurons that expressed nitric oxide synthase (NOS+). The unique combinations of structural and neurochemical features of the three classes of IM neurons suggest different physiological properties and function. The three types of IM neurons were intermingled and likely interconnected in distinct ways, and were innervated by intrinsic neurons within the amygdala, or by external sources, in pathways that underlie fear conditioning and anxiety. PMID:27256508

  17. Simulation of lithium fragment vibrations in graph ita intercalates

    International Nuclear Information System (INIS)

    Frequencies of lithium particle vibrations in aromatic hydrocarbon layers are evaluated (such systems are simulated in a cluster approximation of graphite intercalate property under high metal content). Equilibrium geometric configurations arc determined by quantum-chemical calculations, and harmonie frequencies of vibrations are calculated for Li6 and Li7 in C24H12 coronene shells. It is shown, that under a metal particle inclusion into carbon layers it is, in principle, possible to observe vibration frequencies, exceeding substantially the ones in a face metal cluster state

  18. Capacitors on the basis of intercalate GaSe

    Directory of Open Access Journals (Sweden)

    Kovalyuk Z. D.

    2010-06-01

    Full Text Available The compound GaSe is obtained by the technique of intercalation of a GaSe single crystal in a melt of the ferroelectric salt KNO3. The x-ray analysis of its crystal structure has been carried out and dielectric frequency characteristics of samples has been measured. It is estab-lished, that accumulation of electric charges occurs in the examined examples in frequency area 100—1000 Hz. A sample of filter capacitor has been created on the basis of the re-ceived compounds.

  19. Intercalation of lithium in a III-V semiconductor

    International Nuclear Information System (INIS)

    Direct lithiation of oriented (111)InSb monocrystalline samples, of the n type, was made using n-butyl-lithium in hexane solution, at room temperature. The lithiation process was studied by X-ray diffractometry and with electric measurements. The data obtained from resistivity and Hall coefficients allow to determine a coefficient of lithium diffusion in InSb at room temperature D298K = 1.09 x 10-8 cm2 s-1 according to literature values found out by other methods. A probable mechanism of intercalation is discussed and the process of reversibility is shown. (Author)

  20. Intercalation of small hydrophobic molecules in lipid bilayers containing cholesterol

    Energy Technology Data Exchange (ETDEWEB)

    Worcester, D.L.; Hamacher, K.; Kaiser, H.; Kulasekere, R.; Torbet, J. [Univ. of Missouri, Columbia, MO (United States)

    1994-12-31

    Partitioning of small hydrophobic molecules into lipid bilayers containing cholesterol has been studied using the 2XC diffractometer at the University of Missouri Research Reactor. Locations of the compounds were determined by Fourier difference methods with data from both deuterated and undeuterated compounds introduced into the bilayers from the vapor phase. Data fitting procedures were developed for determining how well the compounds were localized. The compounds were found to be localized in a narrow region at the center of the hydrophobic layer, between the two halves of the bilayer. The structures are therefore intercalated structures with the long axis of the molecules in the plane of the bilayer.

  1. Preparation and capacitive properties of lithium manganese oxide intercalation compound

    International Nuclear Information System (INIS)

    Lithium manganese oxide intercalation compound (Li0.7MnO2) supported on titanium nitride nanotube array (TiN NTA) was applied as cathode electrode material for lithium-ion supercapacitor application. Li0.7MnO2/TiN NTA was fabricated through electrochemical deposition and simultaneous intercalation process using TiN NTA as a substrate, Mn(CH3COO)2 as manganese source, and Li2SO4 as lithium source. The morphology and microstructure of the Li0.7MnO2/TiN NTA were characterized by scanning electron microscopy and X-ray diffraction analysis. The electrochemical performance of the Li0.7MnO2/TiN NTA was investigated by electrochemical impedance spectroscopy, cyclic voltammetry, and galvanostatic charge/discharge measurements. Li0.7MnO2/TiN NTA exhibited higher capacitive performance in Li2SO4 electrolyte solution rather than that in Na2SO4 electrolyte solution, which was due to the different intercalation effects of lithium-ion and sodium-ion. The specific capacitance was improved from 503.3 F g−1 for MnO2/TiN NTA to 595.0 F g−1 for Li0.7MnO2/TiN NTA at a current density of 2 A g−1 in 1.0 M Li2SO4 electrolyte solution, which was due to the intercalation of lithium-ion for Li0.7MnO2. Li0.7MnO2/TiN NTA also kept 90.4 % capacity retention after 1000 cycles, presenting a good cycling stability. An all-solid-state lithium-ion supercapacitor was fabricated and showed an energy density of 82.5 Wh kg−1 and a power density of 10.0 kW kg−1

  2. Role of the intercalated disc in cardiac propagation and arrhythmogenesis

    OpenAIRE

    Kleber, Andre G.; Saffitz, Jeffrey E.

    2014-01-01

    This review article discusses mechanisms underlying impulse propagation in cardiac muscle with specific emphasis on the role of the cardiac cell-to-cell junction, called the “intercalated disc.”The first part of this review deals with the role of gap junction channels, formed by connexin proteins, as a determinant of impulse propagation. It is shown that, depending on the underlying structure of the cellular network, decreasing the conductance of gap junction channels (so-called “electrical u...

  3. DNA intercalator stimulates influenza transcription and virus replication

    Directory of Open Access Journals (Sweden)

    Poon Leo LM

    2011-03-01

    Full Text Available Abstract Influenza A virus uses its host transcription machinery to facilitate viral RNA synthesis, an event that is associated with cellular RNA polymerase II (RNAPII. In this study, various RNAPII transcription inhibitors were used to investigate the effect of RNAPII phosphorylation status on viral RNA transcription. A low concentration of DNA intercalators, such as actinomycin D (ActD, was found to stimulate viral polymerase activity and virus replication. This effect was not observed in cells treated with RNAPII kinase inhibitors. In addition, the loss of RNAPIIa in infected cells was due to the shift of nonphosphorylated RNAPII (RNAPIIa to hyperphosphorylated RNAPII (RNAPIIo.

  4. Antiferro quadrupolar ordering in Fe intercalated few layers graphene

    Directory of Open Access Journals (Sweden)

    Abu Jahid Akhtar

    2013-07-01

    Full Text Available The π electron cloud above and below the honeycomb structure of graphene causes each carbon atom to carry a permanent electric quadrupole moment which can attach any cation to impart interesting physical properties. We have synthesized Fe intercalated graphene structures to investigate tunable magnetic properties as a result of this chemical modification. An interesting antiferro quadrupolar ordering is observed which arises due to a coupling between magnetic dipole moment of Fe and electric quadrupole moment on graphene surface. In contrast to antiferromagnetic Neel temperature (TN, here the ordering temperature (TQ increases from 35.5 K to 47.5 K as the magnetic field is raised upto 1 Tesla.

  5. Intercalation of small hydrophobic molecules in lipid bilayers containing cholesterol

    International Nuclear Information System (INIS)

    Partitioning of small hydrophobic molecules into lipid bilayers containing cholesterol has been studied using the 2XC diffractometer at the University of Missouri Research Reactor. Locations of the compounds were determined by Fourier difference methods with data from both deuterated and undeuterated compounds introduced into the bilayers from the vapor phase. Data fitting procedures were developed for determining how well the compounds were localized. The compounds were found to be localized in a narrow region at the center of the hydrophobic layer, between the two halves of the bilayer. The structures are therefore intercalated structures with the long axis of the molecules in the plane of the bilayer

  6. Preparation and capacitive properties of lithium manganese oxide intercalation compound

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Fang; Xie, Yibing, E-mail: ybxie@seu.edu.cn [Southeast University, School of Chemistry and Chemical Engineering (China)

    2015-12-15

    Lithium manganese oxide intercalation compound (Li{sub 0.7}MnO{sub 2}) supported on titanium nitride nanotube array (TiN NTA) was applied as cathode electrode material for lithium-ion supercapacitor application. Li{sub 0.7}MnO{sub 2}/TiN NTA was fabricated through electrochemical deposition and simultaneous intercalation process using TiN NTA as a substrate, Mn(CH{sub 3}COO){sub 2} as manganese source, and Li{sub 2}SO{sub 4} as lithium source. The morphology and microstructure of the Li{sub 0.7}MnO{sub 2}/TiN NTA were characterized by scanning electron microscopy and X-ray diffraction analysis. The electrochemical performance of the Li{sub 0.7}MnO{sub 2}/TiN NTA was investigated by electrochemical impedance spectroscopy, cyclic voltammetry, and galvanostatic charge/discharge measurements. Li{sub 0.7}MnO{sub 2}/TiN NTA exhibited higher capacitive performance in Li{sub 2}SO{sub 4} electrolyte solution rather than that in Na{sub 2}SO{sub 4} electrolyte solution, which was due to the different intercalation effects of lithium-ion and sodium-ion. The specific capacitance was improved from 503.3 F g{sup −1} for MnO{sub 2}/TiN NTA to 595.0 F g{sup −1} for Li{sub 0.7}MnO{sub 2}/TiN NTA at a current density of 2 A g{sup −1} in 1.0 M Li{sub 2}SO{sub 4} electrolyte solution, which was due to the intercalation of lithium-ion for Li{sub 0.7}MnO{sub 2}. Li{sub 0.7}MnO{sub 2}/TiN NTA also kept 90.4 % capacity retention after 1000 cycles, presenting a good cycling stability. An all-solid-state lithium-ion supercapacitor was fabricated and showed an energy density of 82.5 Wh kg{sup −1} and a power density of 10.0 kW kg{sup −1}.

  7. Effect of a bulky lateral substitution by chlorine atom and methoxy group on self-assembling properties of lactic acid derivatives

    International Nuclear Information System (INIS)

    Several chiral liquid crystalline materials derived from the lactic acid have been studied with the aim to establish the effect of bulky lateral substituents on their self-assembling properties. A chlorine atom and methoxy group have been used as lateral substituents in ortho position to ether group position on phenyl ring far from the chiral centre. All the studied materials possess tilted ferroelectric smectic C* phase in a broad temperature range. In dependence on the molecular structure namely type of lateral substituent and length of the chiral chain, the cholesteric mesophase, orthogonal paraelectric smectic A* and crystal mesophases have been detected. Lateral chlorine substitution results in decrease of both the clearing point and crystallisation temperature as well as in a distinct increase of spontaneous polarization. Bulky methoxy substitution slightly suppresses the spontaneous polarisation but strongly increases the melting point that results in monotropic peculiarity of the SmC* phase. Mesomorphic, spontaneous, structural and dielectric properties of the substituted compounds were established and compared to those of the non-substituted ones in order to contribute to better understanding of the structure–property relationship for such chiral self-assembling materials. - Highlights: • Chiral liquid crystalline materials derived from the lactic acid have been studied. • Effect of bulky lateral substituents on self-assembling properties has been established. • Bulky methoxy substitution suppresses spontaneous polarisation but increases the melting point. • The compounds might have a strong potential for many advanced electro-optic applications

  8. Effect of a bulky lateral substitution by chlorine atom and methoxy group on self-assembling properties of lactic acid derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Stojanović, Maja, E-mail: maja.stojanovic@df.uns.ac.rs [Department of Physics, Faculty of Sciences, University of Novi Sad, Trg D.Obradovića 4, 21000 Novi Sad (Serbia); Bubnov, Alexej [Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague (Czech Republic); Obadović, Dušanka Ž. [Department of Physics, Faculty of Sciences, University of Novi Sad, Trg D.Obradovića 4, 21000 Novi Sad (Serbia); Hamplová, Věra [Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague (Czech Republic); Cvetinov, Miroslav [Department of Physics, Faculty of Sciences, University of Novi Sad, Trg D.Obradovića 4, 21000 Novi Sad (Serbia); Kašpar, Miroslav [Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague (Czech Republic)

    2014-07-01

    Several chiral liquid crystalline materials derived from the lactic acid have been studied with the aim to establish the effect of bulky lateral substituents on their self-assembling properties. A chlorine atom and methoxy group have been used as lateral substituents in ortho position to ether group position on phenyl ring far from the chiral centre. All the studied materials possess tilted ferroelectric smectic C* phase in a broad temperature range. In dependence on the molecular structure namely type of lateral substituent and length of the chiral chain, the cholesteric mesophase, orthogonal paraelectric smectic A* and crystal mesophases have been detected. Lateral chlorine substitution results in decrease of both the clearing point and crystallisation temperature as well as in a distinct increase of spontaneous polarization. Bulky methoxy substitution slightly suppresses the spontaneous polarisation but strongly increases the melting point that results in monotropic peculiarity of the SmC* phase. Mesomorphic, spontaneous, structural and dielectric properties of the substituted compounds were established and compared to those of the non-substituted ones in order to contribute to better understanding of the structure–property relationship for such chiral self-assembling materials. - Highlights: • Chiral liquid crystalline materials derived from the lactic acid have been studied. • Effect of bulky lateral substituents on self-assembling properties has been established. • Bulky methoxy substitution suppresses spontaneous polarisation but increases the melting point. • The compounds might have a strong potential for many advanced electro-optic applications.

  9. PipPhos and MorfPhos : Privileged monodentate phosphoramidite ligands for rhodium-catalyzed asymmetric hydrogenation

    NARCIS (Netherlands)

    Bernsmann, Heiko; van den Berg, M; Hoen, Robert; Minnaard, AJ; Mehler, G; Reetz, MT; De Vries, JG; Feringa, BL

    2005-01-01

    A library of 20 monodentate phosphoramidite ligands has been prepared and applied in rhodium-catalyzed asymmetric hydrogenation. This resulted in the identification of two ligands, PipPhos and MorfPhos, that afford excellent and in several cases unprecedented enantioselectivities in the hydrogenatio

  10. The Rôle of the Element Rhodium in the Hyperbolic Law of the Periodic Table of Elements

    OpenAIRE

    Khazan A.

    2008-01-01

    The role of the element rhodium as an independent affirmation of calculations by the Hyperbolic Law and validity of all its relations is shown herein. The deviation in cal- culation by this method of the atomic mass of heaviest element is 0.0024%, and its coefficient of scaling 0.001–0.005%

  11. Rhodium(III)-Catalyzed C-H Activation/Annulation with Vinyl Esters as an Acetylene Equivalent

    OpenAIRE

    Webb, NJ; Marsden, SP; Raw, SA

    2014-01-01

    The behavior of electron-rich alkenes in rhodium-catalyzed C–H activation/annulation reactions is investigated. Vinyl acetate emerges as a convenient acetylene equivalent, facilitating the synthesis of sixteen 3,4-unsubstituted isoquinolones, as well as select heteroaryl-fused pyridones. The complementary regiochemical preferences of enol ethers versus enol esters/enamides is discussed

  12. Mono and dinuclear iridium, rhodium and ruthenium complexes containing chelating carboxylato pyrazine ligands: Synthesis, molecular structure and electrochemistry

    Czech Academy of Sciences Publication Activity Database

    Govindaswamy, P.; Therrien, B.; Süss-Fink, G.; Štěpnička, P.; Ludvík, Jiří

    2007-01-01

    Roč. 692, č. 8 (2007), s. 1661-1671. ISSN 0022-328X R&D Projects: GA MŠk LC510; GA MŠk(CZ) LC06070 Institutional research plan: CEZ:AV0Z40400503 Keywords : dinuclear complexes * iridium * rhodium * ruthenium * electrochemistry Subject RIV: CG - Electrochemistry Impact factor: 2.168, year: 2007

  13. Selective Synthesis of Isoquinolines by Rhodium(III)-Catalyzed C-H/N-H Functionalization with α-Substituted Ketones.

    Science.gov (United States)

    Li, Jie; Zhang, Zhao; Tang, Mengyao; Zhang, Xiaolei; Jin, Jian

    2016-08-01

    A rhodium(III)-catalyzed C-H/N-H bond functionalization for the synthesis of 1-aminoisoquinolines from aryl amidines and α-MsO/TsO/Cl ketones was achieved under mild reaction conditions. Thus, this approach provides a practical method for the site-selective synthesis of various synthetically valuable isoquinolines with wide functional group tolerance. PMID:27441726

  14. The Rôle of the Element Rhodium in the Hyperbolic Law of the Periodic Table of Elements

    Directory of Open Access Journals (Sweden)

    Khazan A.

    2008-07-01

    Full Text Available The role of the element rhodium as an independent affirmation of calculations by the Hyperbolic Law and validity of all its relations is shown herein. The deviation in cal- culation by this method of the atomic mass of heaviest element is 0.0024%, and its coefficient of scaling 0.001–0.005%

  15. Direct Synthesis of 5-Aryl Barbituric Acids by Rhodium(II)-Catalyzed Reactions of Arenes with Diazo Compounds**

    OpenAIRE

    Best, Daniel; Burns, David J.; Lam, Hon Wai

    2015-01-01

    A commercially available rhodium(II) complex catalyzes the direct arylation of 5-diazobarbituric acids with arenes, allowing straightforward access to 5-aryl barbituric acids. Free N—H groups are tolerated on the barbituric acid, with no complications arising from N—H insertion processes. This method was applied to the concise synthesis of a potent matrix metalloproteinase (MMP) inhibitor.

  16. Direct Synthesis of 5-Aryl Barbituric Acids by Rhodium(II)-Catalyzed Reactions of Arenes with Diazo Compounds**

    Science.gov (United States)

    Best, Daniel; Burns, David J; Lam, Hon Wai

    2015-01-01

    A commercially available rhodium(II) complex catalyzes the direct arylation of 5-diazobarbituric acids with arenes, allowing straightforward access to 5-aryl barbituric acids. Free N—H groups are tolerated on the barbituric acid, with no complications arising from N—H insertion processes. This method was applied to the concise synthesis of a potent matrix metalloproteinase (MMP) inhibitor. PMID:25959544

  17. Direct Synthesis of 5-Aryl Barbituric Acids by Rhodium(II)-Catalyzed Reactions of Arenes with Diazo Compounds.

    Science.gov (United States)

    Best, Daniel; Burns, David J; Lam, Hon Wai

    2015-06-15

    A commercially available rhodium(II) complex catalyzes the direct arylation of 5-diazobarbituric acids with arenes, allowing straightforward access to 5-aryl barbituric acids. Free N-H groups are tolerated on the barbituric acid, with no complications arising from N-H insertion processes. This method was applied to the concise synthesis of a potent matrix metalloproteinase (MMP) inhibitor. PMID:25959544

  18. Gold vs Rhodium Catalysis: Tuning Reactivity through Catalyst Control in the C-H Alkynylation of Isoquinolones.

    Science.gov (United States)

    Shaikh, Aslam C; Shinde, Dinesh R; Patil, Nitin T

    2016-03-01

    A site-selective C-4/C-8 alkynylation of isoquinolones catalyzed by gold and rhodium complexes is reported. A broad range of synthetically useful functional groups (-F, -Cl, -Br, -CF3, -OMe, alkyl, etc.) were tolerated, providing an efficient and robust protocol for the synthesis either C-4- or C-8-alkynylated isoquinolones. PMID:26886569

  19. Catalytic, Enantioselective Addition of Alkyl Radicals to Alkenes via Visible-Light-Activated Photoredox Catalysis with a Chiral Rhodium Complex.

    Science.gov (United States)

    Huo, Haohua; Harms, Klaus; Meggers, Eric

    2016-06-01

    An efficient enantioselective addition of alkyl radicals, oxidatively generated from organotrifluoroborates, to acceptor-substituted alkenes is catalyzed by a bis-cyclometalated rhodium catalyst (4 mol %) under photoredox conditions. The practical method provides yields up to 97% with excellent enantioselectivities up to 99% ee and can be classified as a redox neutral, electron-transfer-catalyzed reaction. PMID:27218134

  20. Rhodium nanoparticles supported on carbon nanofibers as an arene hydrogenation catalyst highly tolerant to a coexisting epoxido group.

    Science.gov (United States)

    Motoyama, Yukihiro; Takasaki, Mikihiro; Yoon, Seong-Ho; Mochida, Isao; Nagashima, Hideo

    2009-11-01

    Rhodium nanoparticles supported on a carbon nanofiber (Rh/CNF-T) show high catalytic activity toward arene hydrogenation under mild conditions in high turnover numbers without leaching the Rh species; the reaction is highly tolerant to epoxido groups, which often undergo ring-opening hydrogenation with conventional catalysts. PMID:19788269

  1. Ion flotation of rhodium(III) and palladium(II) with anionic surfactants.

    Science.gov (United States)

    He, X C

    1991-03-01

    The ion flotation of rhodium(III) and palladium(II) with some anionic surfactants has been investigated. Two flotation procedures are proposed for the separation of some platinum metals, based on differences in the kinetic properties of the chloro-complexes of rhodium(III), palladium(II) and platinum(IV). The first involves the selective flotation of Rh(H(2)O)(3+)(6) from PdCl(2-)(4) and PtCl(2-)(6) in dilute hydrochloric acid with sodium dodecylbenzenesulfonate (SDBS). After precipitation of the hydroxide and redissolution in dilute acid, the Rh(III) is converted into Rh(H(2)O)(3+)(6), Pd(II) and Pt(IV) remaining as PdCl(2-)(4) and PtCl(2-)(6) respectively, and separation is achieved by floating the Rh(H(2)O)(3+)(6) with SDBS. The second is for separation of Pd(II). Prior to flotation, the solution of PdCl(2-)(4) and PtCl(2-)(6) is heated with ammonium acetate to convert PdCl(2-)(4) into Pd(NH(3))(2+)(4). The chloro-complex of Pt(IV) is unaffected. The complex cation, Pd(NH(3))(2+)(4), is then selectively floated with SDBS. The procedures are fast, simple and do not require expensive reagents and apparatus. PMID:18965147

  2. Signal anticipation of rhodium self powered neutron detectors for on-line applications

    International Nuclear Information System (INIS)

    Rhodium self powered neutron detectors (SPND) have been used for a long time in the experimental devices at the SILOE reactor. In a time-dependent neutron flux, the rhodium SPND behaves as a first order linear system. Consequently, the response of the SPND is not similar to the incident flux evolution because time constants are involved. In order to draw-out the true flux variation, a convolution type method is to be used. As a result of the time discretization of the linear differential system that couples the SPND current to the neutron flux, one has to use differential equations. The resolution of these equations is equivalent to an approximately inversion of the initial system. The numerical method described above has been applied in a microcomputer system, in order to treat the SPND signal by a computer-driven millivolmeter. Nowadays, devices for transient experiments in the SILOE reactor are driven by a P.C. system, based on this numerical approach and using an independent data acquisition; the reliability and the ergonomics aspects have been taken into account. The modular conception of the system allows easy further developments for flux monitoring in various surroundings

  3. Tracking the shape-dependent sintering of platinum-rhodium model catalysts under operando conditions.

    Science.gov (United States)

    Hejral, Uta; Müller, Patrick; Balmes, Olivier; Pontoni, Diego; Stierle, Andreas

    2016-01-01

    Nanoparticle sintering during catalytic reactions is a major cause for catalyst deactivation. Understanding its atomic-scale processes and finding strategies to reduce it is of paramount scientific and economic interest. Here, we report on the composition-dependent three-dimensional restructuring of epitaxial platinum-rhodium alloy nanoparticles on alumina during carbon monoxide oxidation at 550 K and near-atmospheric pressures employing in situ high-energy grazing incidence x-ray diffraction, online mass spectrometry and a combinatorial sample design. For platinum-rich particles our results disclose a dramatic reaction-induced height increase, accompanied by a corresponding reduction of the total particle surface coverage. We find this restructuring to be progressively reduced for particles with increasing rhodium composition. We explain our observations by a carbon monoxide oxidation promoted non-classical Ostwald ripening process during which smaller particles are destabilized by the heat of reaction. Its driving force lies in the initial particle shape which features for platinum-rich particles a kinetically stabilized, low aspect ratio. PMID:26957204

  4. Tracking the shape-dependent sintering of platinum–rhodium model catalysts under operando conditions

    Science.gov (United States)

    Hejral, Uta; Müller, Patrick; Balmes, Olivier; Pontoni, Diego; Stierle, Andreas

    2016-01-01

    Nanoparticle sintering during catalytic reactions is a major cause for catalyst deactivation. Understanding its atomic-scale processes and finding strategies to reduce it is of paramount scientific and economic interest. Here, we report on the composition-dependent three-dimensional restructuring of epitaxial platinum–rhodium alloy nanoparticles on alumina during carbon monoxide oxidation at 550 K and near-atmospheric pressures employing in situ high-energy grazing incidence x-ray diffraction, online mass spectrometry and a combinatorial sample design. For platinum-rich particles our results disclose a dramatic reaction-induced height increase, accompanied by a corresponding reduction of the total particle surface coverage. We find this restructuring to be progressively reduced for particles with increasing rhodium composition. We explain our observations by a carbon monoxide oxidation promoted non-classical Ostwald ripening process during which smaller particles are destabilized by the heat of reaction. Its driving force lies in the initial particle shape which features for platinum-rich particles a kinetically stabilized, low aspect ratio. PMID:26957204

  5. Reversibility of hydrogen chemisorption on a ceria-supported rhodium catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Bernal, S.; Calvino, J.J.; Cifredo, G.A.; Izquierdo, J.M. Rodriguez (Univ. de Cadiz, Perto Real (Spain)); Perrichon, V.; Laachir, A. (Inst. de Recherches sur la Catalyse (France))

    1992-09-01

    Cerium dioxide is an important component of the so-called three-way catalysts. This work reports on some new aspects of the chemistry of hydrogen-ceria systems. It is shown that, at room temperature, in the presence of highly dispersed rhodium, ceria chemisorbs large amounts of hydrogen. As deduced from magnetic measurements carried out in situ, this spillover process leads to the reduction of ceria to an extent of 21% of the total amount of cerium ions present in the sample, which is roughly equivalent to the complete surface reduction of the oxide. It is found that over a highly hydroxylated sample the reduction of ceria induced by the spillover process is partly reversible even at 295 K. If the sample is pumped off at 773 K, the initial oxidation state of ceria is almost completely recovered. Both the rate and extent of hydrogen chemisorption on ceria were found to be sensitive to the specific pretreatment applied to the catalyst. Over bare ceria, hydrogen chemisorption at 298 K was negligible, temperatures as high as 473 K being necessary to activate the process. In contrast to the rhodium-containing catalyst, over pure ceria the desorption of hydrogen leads to a much larger extent to water formation, thus revealing a deeper irreversible reduction of the oxide.

  6. Olefin hydroformylation by sol-gel entrapped rhodium catalysts bearing hydrolyzable ligands

    International Nuclear Information System (INIS)

    Rhodium complexes prepared in situ from [Rh(OMe)(COD)]2, [Rh(CO)2(acac)], [Rh(cod)(acac)] or [Rh(cod)(PPh3)2]+BPh4- with ligands as HS(CH2)3Si(OMe)3, Ph2P(CH2)2S(CH2)3Si(OMe)3 or Ph2P(CH2)2Si(OMe)3 were immobilized in inorganic and hybrid silica matrices via the sol-gel process. The inorganic matrices were prepared with tetramethyl orthosilicate while for the hybrid ones 1,4-bis(triethoxysilyl)benzene or 1,2-bis(triethoxysilyl)ethane were used as co-condensation agents. The system based on [Rh(CO)2(acac)]/ Ph2P(CH2)2S(CH2)3Si(OMe)3 was active in the hydroformylation of 1-hexene and 1-octadecene without any rhodium leaching. It could also be used in the absence of a solvent, as observed in the hydroformylation of 1-decene. Although the best system was based on a hybrid microporous matrix, no straightforward correlation between matrix composition, condensation degree and surface properties could be found. (author)

  7. Tris-(1,3-diaryltriazenide) complexes of rhodium - Synthesis, structure and, spectral and electrochemical properties

    Indian Academy of Sciences (India)

    Chhandasi Guharoy; Michael G B Drew; Samaresh Bhattacharya

    2009-05-01

    Reaction of 1,3-diaryltriazenes (abbreviated in general as HL-R, where R stands for the para-substituent in the aryl fragment and H stands for the dissociable hydrogen atom, R = OCH3, CH3, H, Cl, NO2) with [Rh(PPh3)2(CO)Cl] in ethanol in the presence of NEt3 produces a series of trisdiaryltriazenide complexes of rhodium of type [Rh(L-R)3], where the triazenes are coordinated to rhodium as monoanionic, bidentate N,N-donors. Structure of the [Rh(L-OCH3)3] complex has been determined by X-ray crystallography. The complexes are diamagnetic, and show characteristic 1H NMR signals and intense MLCT transitions in the visible region. They also fluoresce in the visible region under ambient condition while excited at around 400 nm. Cyclic voltammetry on these complexes shows a Rh(III)-Rh(IV) oxidation (within 0.84-1.67 V vs SCE), followed by an oxidation of the coordinated triazene ligand (except the R = NO2 complex). An irreversible reduction of the coordinated triazene is also observed for all the complexes below -1.03 V vs SCE.

  8. Rhodium thin film-carbon nanotube nanostructures: Synthesis, characterization and electron transfer properties

    International Nuclear Information System (INIS)

    Rh thin films have been synthesized onto carbon nanotubes by pulsed laser deposition under vacuum and under 266 Pa of helium background pressure. Field emission scanning electron microscopy revealed two types of Rh films: (i) Rh film fabricated under vacuum was smooth and of closed structure and (ii) Rh prepared at 266 Pa of He was porous. Transmission electron microscopy showed that the smooth Rh film was made of highly interconnected particles of 2 nm diameter, whereas the porous film had a morphology of particles arranged into columns with particles having an average diameter of 5 nm. In addition, using high resolution transmission electron microscopy images, the Rh film thickness could be estimated to be about 20 nm. X-ray diffraction pattern showed well-crystallized thin films with a (111) intense orientation. X-ray photoelectron spectroscopy confirmed the presence of metallic Rh at the surface of the carbon nanotubes. Preliminary evaluation of the electron transfer properties showed that porous Rh-carbon nanotubes exhibited reduced oxophilicity than smooth Rh. In addition, the porous Rh film offered larger electrochemical stability window between the onset of hydrogen adsorption and Rh oxide formation. Such interesting properties have important implications in many electroanalytical applications. - Highlights: • Pulsed laser synthesis used to deposit rhodium thin films onto carbon nanotubes. • Smooth and porous rhodium films verified by electron microscopy analyses • Electron transfer properties studied in sulfuric acid solution

  9. Thick rhodium electrodeposition on copper backing as the target for production of palladium-103

    International Nuclear Information System (INIS)

    The Rh target preparation for production of 103Pd was investigated by using a thick electrodeposition of rhodium metal on a copper backing. The electrodeposition experiments were performed in acidic sulfate media using RhCl3 x 3H2O, Rh2(SO4)3 (recovered from hydrochloric acid solution) and also in the commercially available Rhodex plating baths. For high current beam irradiation of a Rh target, the qualities of the deposit of the three baths were compared in terms of thermal shock, crack-free and morphology criteria. The quality of the plating obtained from a sulfate bath [Rh2(SO4)3] was comparable with the one obtained from commercially available Rhodex bath. The optimum conditions of the electrodepositions were as follows: 4.8 g rhodium [as Rh2(SO4)3], pH 2, DC current density of ca 8.5 mA x cm-2, 1% sulfamic acid (w/v) and temperature 40-60 deg C. (author)

  10. Tracking the shape-dependent sintering of platinum-rhodium model catalysts under operando conditions

    Science.gov (United States)

    Hejral, Uta; Müller, Patrick; Balmes, Olivier; Pontoni, Diego; Stierle, Andreas

    2016-03-01

    Nanoparticle sintering during catalytic reactions is a major cause for catalyst deactivation. Understanding its atomic-scale processes and finding strategies to reduce it is of paramount scientific and economic interest. Here, we report on the composition-dependent three-dimensional restructuring of epitaxial platinum-rhodium alloy nanoparticles on alumina during carbon monoxide oxidation at 550 K and near-atmospheric pressures employing in situ high-energy grazing incidence x-ray diffraction, online mass spectrometry and a combinatorial sample design. For platinum-rich particles our results disclose a dramatic reaction-induced height increase, accompanied by a corresponding reduction of the total particle surface coverage. We find this restructuring to be progressively reduced for particles with increasing rhodium composition. We explain our observations by a carbon monoxide oxidation promoted non-classical Ostwald ripening process during which smaller particles are destabilized by the heat of reaction. Its driving force lies in the initial particle shape which features for platinum-rich particles a kinetically stabilized, low aspect ratio.

  11. Duplex-Selective Ruthenium-based DNA Intercalators

    Science.gov (United States)

    Shade, Chad M.; Kennedy, Robert D.; Rouge, Jessica L.; Rosen, Mari S.; Wang, Mary X.; Seo, Soyoung E.; Clingerman, Daniel J.

    2016-01-01

    We report the design and synthesis of small molecules that exhibit enhanced luminescence in the presence of duplex rather than single-stranded DNA. The local environment presented by a well-known [Ru(dipyrido[2,3-a:3',2'-c]phenazine)L2]2+-based DNA intercalator was modified by functionalizing the bipyridine ligands with esters and carboxylic acids. By systematically varying the number and charge of the pendant groups, it was determined that decreasing the electrostatic interaction between the intercalator and the anionic DNA backbone reduced single-strand interactions and translated to better duplex specificity. In studying this class of complexes, a single RuII complex emerged that selectively luminesces in the presence of duplex DNA with little to no background from interacting with single stranded DNA. This complex shows promise as a new dye capable of selectively staining double versus single-stranded DNA in gel electrophoresis, which cannot be done with conventional SYBR dyes. PMID:26119581

  12. Microscopic physical and chemical properties of graphite intercalation compounds

    Energy Technology Data Exchange (ETDEWEB)

    Eklund, P.C.

    1992-08-24

    Optical spectroscopy (Raman, FTIR and Reflection ) was used to study a variety of acceptor- and donor-type compounds synthesized to determine the microscopic models consistent with the spectrocsopic results. General finding is that the electrical conduction properties of these compounds can be understood on the basis that the intercalation of atomic and/or molecular species between the host graphite layers either raises or lowers the Fermi level (E{sub F)} in a graphitic band structure. This movement of E{sub F} is accomplished via a charge transfer of electrons from the intercalate layers to the graphitic layers (donor compounds), or vice versa (acceptor compounds). Furthermore, the band structure must be modified to take into account the layers of charge that occur as a result of the charge transfer. This charge layering introduces additional bands of states near E{sub F}, which are discussed. Charge-transfer also induces a perturbation of the graphitic normal mode frequencies which can be understood as the result of a contraction (acceptor compounds) or expansion (donor compounds) of the intralayer C-C bonds. Ab-initio calculations support this view and are in reasonable agreement with experimental data.

  13. Nuclear magnetic resonance study of fluorine-graphite intercalation compounds

    International Nuclear Information System (INIS)

    To study the origin of semimetal-metal and metal-insulator transformations, localization effects and C-F bonding in fluorine-intercalated graphite CxF, 13C and 19F NMR investigations have been carried out for a wide range of fluorine content, 3.8≤x≤12.7. Fluorine spectra for small fluorine content, x>8, are attributed to mobile fluorine acceptor species which are responsible for the increase of electric conductivity in the dilute compound. When increasing the fluorine content to x∼8 corresponding to the maximum electric conductivity, covalent C-F bonds start to occur. The number of these bonds grows with fluorine content resulting in a decrease in conductivity which is caused by a percolation mechanism rather than by a change in bond length. A difference in 19F chemical shift for fluorine-intercalated graphite CxF and covalent graphite fluoride (CF)n has been observed and is attributed to different C-F bonding in these compounds. (author)

  14. ROLE OF THE INTERCALATED DISC IN CARDIAC PROPAGATION AND ARRHYTHMOGENESIS

    Directory of Open Access Journals (Sweden)

    Andre Georges Kleber

    2014-10-01

    Full Text Available AbstractThis review article discusses mechanisms underlying impulse propagation in cardiac muscle with specific emphasis on the role of the cardiac cell-to-cell junction, called the intercalated disc. The first part of this review deals with the role of gap junction channels, formed by connexin proteins, as a determinant of impulse propagation. It is shown that, depending on the underlying structure of the cellular network, decreasing the conductance of gap junction channels (so-called electrical uncoupling may either only slow, or additionally stabilize propagation and reverse unidirectional propagation block to bidirectional propagation. This is because the safety factor for propagation increases with decreasing intercellular electrical conductance. The role of heterogeneous connexin expression, which may be present in disease states, is also discussed. The hypothesis that so-called ephaptic impulse transmission plays a role in heart and can substitute for electrical coupling has been revived recently. Whereas ephaptic transmission can be demonstrated in theoretical simulations, direct experimental evidence has not yet been presented.The second part of this review deals with the interaction of three protein complexes at the intercalated disc: (1 desmosomal and adherers junction proteins, (2 ion channel proteins, and (3 gap junction channels consisting of connexins. Recent work has revealed multiple interactions between these three protein complexes which occur, at least in part, at the level of protein trafficking. Such interactions are likely to play an important role in the pathogenesis of arrhythmogenic cardiomyopathy, and may reveal new therapeutic concepts and targets.

  15. Modeling of alkyl quaternary ammonium cations intercalated into montmorillonite lattice

    International Nuclear Information System (INIS)

    Highlights: ► The modification of montmorillonites by three surfactants increases the basal spacing. ► The model proposed show a bilayer conformation for the surfactant ODTMA. ► The DODMA and TOMA surfactants adopt a paraffin type arrangement. ► Behavior of surfactants in interlayer space was confirmed by TGA and ATR analysis. - Abstract: The objective of this work was to study the conformation of the quaternary ammonium cations viz., octadecyl trimethyl ammonium (ODTMA), dioctadecyl dimethyl ammonium (DMDOA) and trioctadecyl methyl ammonium (TOMA) intercalated within montmorillonite. The modified montmorillonite was characterized by X-ray diffraction in small angle (SAXS), thermal analysis (TGA) and infrared spectroscopy of attenuated total reflection (ATR). The modification of organophilic montmorillonites by the three surfactants ODTMA, DMDOA and TOMA increases the basal spacing from their respective intercalated distances of 1.9 nm, 2.6 nm and 3.4 nm respectively. The increase in the spacing due to the basic organic modification was confirmed by the results of thermal analysis (TGA) and infrared spectroscopy (ATR), and also supported by theoretical calculations of longitudinal and transversal chain sizes of these alkyl quaternary ammonium cations

  16. Superconductivity of graphite intercalation compounds with alkali-metal amalgams

    International Nuclear Information System (INIS)

    Superconductivity of the alkali-metal amalgam graphite intercalation compounds of stage 1 (C4KHg, C4RbHg) and stage 2 (C8KHg, C8RbHg) has been studied as well as that of the pristine amalgams (KHg, RbHg). The transition temperatures are 0.73, 0.99, 1.90, and 1.40 K for C4KHg, C4RbHg, C8KHg, and C8RbHg, respectively. The critical-field anisotropy ratio H/sup parallel//sub c/2/H/sup perpendicular//sub c/2 is about 10 for the stage 1 and about 15 to 40 for the stage 2. It is argued that electrons in the intercalant bands rather than the graphitic bands play the main role in the superconductivity. An interesting feature is that the stage-2 compound, which has a lower density of states at the Fermi level, has a higher transition temperature than the corresponding state-1 compound

  17. NLP-1: a DNA intercalating hypoxic cell radiosensitizer and cytotoxin

    International Nuclear Information System (INIS)

    The 2-nitroimidazole linked phenanthridine, NLP-1 (5-[3-(2-nitro-1-imidazoyl)-propyl]-phenanthridinium bromide), was synthesized with the rationale of targeting the nitroimidazole to DNA via the phenanthridine ring. The drug is soluble in aqueous solution (greater than 25 mM) and stable at room temperature. It binds to DNA with a binding constant 1/30 that of ethidium bromide. At a concentration of 0.5 mM, NLP-1 is 8 times more toxic to hypoxic than aerobic cells at 37 degrees C. This concentration is 40 times less than the concentration of misonidazole, a non-intercalating 2-nitroimidazole, required for the same degree of hypoxic cell toxicity. The toxicity of NLP-1 is reduced at least 10-fold at 0 degrees C. Its ability to radiosensitize hypoxic cells is similar to misonidazole at 0 degrees C. Thus the putative targeting of the 2-nitroimidazole, NLP-1, to DNA, via its phenanthridine group, enhances its hypoxic toxicity, but not its radiosensitizing ability under the present test conditions. NLP-1 represents a lead compound for intercalating 2-nitroimidazoles with selective toxicity for hypoxic cells

  18. Methotrexate intercalated ZnAl-layered double hydroxide

    Science.gov (United States)

    Chakraborty, Manjusha; Dasgupta, Sudip; Soundrapandian, Chidambaram; Chakraborty, Jui; Ghosh, Swapankumar; Mitra, Manoj K.; Basu, Debabrata

    2011-09-01

    The anticancerous drug methotrexate (MTX) has been intercalated into an ZnAl-layered double hydroxide (LDH) using an anion exchange technique to produce LDH-MTX hybrids having particle sizes in the range of 100-300 nm. X-ray diffraction studies revealed increases in the basal spacings of ZnAl-LDH-MTX hybrid on MTX intercalation. This was corroborated by the transmission electron micrographs, which showed an increase in average interlayer spacing from 8.9 Å in pristine LDH to 21.3 Å in LDH-MTX hybrid. Thermogravimetric analyses showed an increase in the decomposition temperature for the MTX molecule in the LDH-MTX hybrid indicating enhanced thermal stability of the drug molecule in the LDH nanovehicle. The cumulative release profile of MTX from ZnAl-LDH-MTX hybrids in phosphate buffer saline (PBS) at pH 7.4 was successfully sustained for 48 h following Rigter-Peppas model release kinetics via diffusion.

  19. Scaling Relations for Intercalation Induced Damage in Electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chien-Fan; Barai, Pallab; Smith, Kandler; Mukherjee, Partha P.

    2016-06-01

    Mechanical degradation, owing to intercalation induced stress and microcrack formation, is a key contributor to the electrode performance decay in lithium-ion batteries (LIBs). The stress generation and formation of microcracks are caused by the solid state diffusion of lithium in the active particles. In this work, scaling relations are constructed for diffusion induced damage in intercalation electrodes based on an extensive set of numerical experiments with a particle-level description of microcrack formation under disparate operating and cycling conditions, such as temperature, particle size, C-rate, and drive cycle. The microcrack formation and evolution in active particles is simulated based on a stochastic methodology. A reduced order scaling law is constructed based on an extensive set of data from the numerical experiments. The scaling relations include combinatorial constructs of concentration gradient, cumulative strain energy, and microcrack formation. The reduced order relations are further employed to study the influence of mechanical degradation on cell performance and validated against the high order model for the case of damage evolution during variable current vehicle drive cycle profiles.

  20. Thermal Stability of Modified i-Motif Oligonucleotides with Naphthalimide Intercalating Nucleic Acids

    DEFF Research Database (Denmark)

    El-Sayed, Ahmed Ali; Pedersen, Erik B.; Khaireldin, Nahid Y.

    2016-01-01

    naphthalimide (1H-benzo[de]isoquinoline-1,3(2H)-dione) as the intercalating nucleic acid. The stabilities of i-motif structures with inserted naphthalimide intercalating nucleotides were studied using UV melting temperatures (Tm) and circular dichroism spectra at different pH values and conditions (crowding and...

  1. Potassium-intercalated H2Pc films : Alkali-induced electronic and geometrical modifications

    NARCIS (Netherlands)

    Nilson, K.; Ahlund, J.; Shariati, M. -N.; Schiessling, J.; Palmgren, P.; Brena, B.; Gothelid, E.; Hennies, F.; Huismans, Y.; Evangelista, F.; Rudolf, P.; Gothelid, M.; Martensson, N.; Puglia, C.; Åhlund, J.; Göthelid, E.; Göthelid, M.; Mårtensson, N.

    2012-01-01

    X-ray spectroscopy studies of potassium intercalated metal-free phthalocyanine multilayers adsorbed on Al(110) have been undertaken. Photoelectron spectroscopy measurements show the presence of several charge states of the molecules upon K intercalation, due to a charge transfer from the alkali. In

  2. Interlayer Structure of Bioactive Molecule, 2-Aminoethanesulfonate, Intercalated into Calcium-Containing Layered Double Hydroxides

    Directory of Open Access Journals (Sweden)

    Tae-Hyun Kim

    2012-01-01

    Full Text Available We have successfully intercalated 2-aminoethanesulfonate, a well-known biomolecule taurine, into calcium-containing layered double hydroxides via optimized solid phase intercalation. According to X-ray diffraction patterns and infrared spectroscopy, it was revealed that the intercalated taurine molecules were each directly coordinated to other calcium cation and arranged in a zig-zag pattern. Scanning electron microscopy showed that the particle size and morphology of the LDHs were not affected by the solid phase intercalation, and the surface of intercalates was covered by organic moieties. From ninhydrin amine detection tests, we confirmed that most of the taurine molecules were well stabilized between the calcium-containing LDH layers.

  3. Atomic force microscopy study of anion intercalation into highly oriented pyrolytic graphite

    Energy Technology Data Exchange (ETDEWEB)

    Alliata, D.; Haering, P.; Haas, O.; Koetz, R. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Siegenthaler, H. [University of Berne (Switzerland)

    1999-08-01

    In the context of ion transfer batteries, we studied highly oriented pyrolytic graphite (HOPG) in perchloric acid, as a model to elucidate the mechanism of electrochemical intercalation in graphite. Aim of the work is the local and time dependent investigation of dimensional changes of the host material during electrochemical intercalation processes on the nanometer scale. We used atomic force microscopy (AFM), combined with cyclic voltammetry, as in-situ tool of analysis during intercalation and expulsion of perchloric anions into the HOPG electrodes. According to the AFM measurements, the HOPG interlayer spacing increases by 32% when perchloric anions intercalate, in agreement with the formation of stage IV of graphite intercalation compounds. (author) 3 figs., 3 refs.

  4. Melamine/Stearic Acid Composite Nanowires and Vesicles with an Intercalated Nanostructure Prepared through NCCM Method

    Institute of Scientific and Technical Information of China (English)

    Juan Guo; Dao-yong Chen

    2012-01-01

    A solvent-non-solvent method invented in our laboratory for preparing non-covalently connected micelles (NCCM) was used to intercalate melamine (MA) molecules into stearic acid (SA) bilayers to form the composite nanoparticles with an intercalated nanostructure in which a melamine bilayer is sandwiched between two stearic acid bilayers,NCCM method helps to sufficiently mix the two components in nanospace and meanwhile inhibits the strong tendency of self-crystallization of MA,leading to the intercalation.Although the nanoparticles have a regular inner structure,the primary MA/SA nanoparticles have an irregular morphology.Regular nanoparticles were obtained through annealing the suspension of the primary nanoparticles.Through annealing at different temperatures,the MA/SA composite nanowires and vesicles with an intercalated structure were prepared respectively.It is proposed that the morphological change results from the change in the intercalated structure.

  5. Dynamics of Intercalation/De-Intercalation of Rhodamine B during the Polymorphic Transformation of CdAl Layered Double Hydroxide to the Brucite-Like Cadmium Hydroxide

    KAUST Repository

    Saliba, Daniel

    2016-06-23

    Cadmium-Aluminum layered double hydroxide (CdAl LDH) is thermodynamically unstable and transforms to Cd(OH)2 and Al(OH)3 in a short period of time. We present a reaction-diffusion framework that enables us to use in situ steady-state fluorescence spectroscopy to study the kinetics of intercalation of a fluorescent probe (Rhodamine B (RhB)) during the formation of the CdAl LDH and its de-intercalation upon the conversion of the LDH phase to the β phase (Cd(OH)2). The method involves the diffusion of sodium hydroxide into a hydrogel gel matrix containing the aluminum and cadmium ions as well as the species we wish to incorporate in the interlayers of the LDH. The existence of RhB between the LDH layers and its expel during the transition into the β phase are proved via fluorescence microscopy, XRD and ssNMR. The activation energies of intercalation and de-intercalation of RhB are computed and show dependence on the cationic ratio of the corresponding LDH. We find that the energies of de- intercalation are systematically higher than those of intercalation proving that the dyes are stabilized due to the probe-brucite sheets interactions.

  6. Leading research on supermetals. Part 1. Bulky material (iron system); Supermetal no sendo kenkyu. 1. Ogata sozai (tetsukei)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-03-01

    For further improvement of iron system materials, supermetals with ultimate characteristics were researched. Since their strength and toughness have been improved with grain refinement by thermomechanical treatment, improvement of single-phase steel is nearly completed, and the study on ultra-fine multi-phase steel is indispensable. Bulky materials are also restrained from grain refinement because of the capability of existing processing facilities. Making a breakthrough in such restraint requires a challenge to high-speed rolling, repeated shear deformation and ultra-high strain rate process beyond conventional technologies. Further improvement of microstructure and dynamic characteristics requires other energies such as magnetism as well as mechanical energy. {gamma}-{alpha} phase transition important for structure control of steel materials is dependent on magnetism. The study on structure control and characteristics improvement under ferromagnetic field is essential in the future. Material improvement such as reduction of impurities and circulating elements, environmental measures, and mechanical alloying remain as issues to be studied. 224 refs., 176 figs., 18 tabs.

  7. Total digestibility and in situ degradability of bulky diets with the inclusion of ionophores or probiotics for cattle and buffaloes

    Directory of Open Access Journals (Sweden)

    Lúcia Maria Zeoula

    2014-09-01

    Full Text Available The effects of ionophores (monensin and probiotic (Saccharomyces cerevisiae + selenium + chromium in diets with 80% forage were evaluated on the digestibility of nutrients. Three buffaloes, Murrah (Bubalus bubalis and three cattle, Holstein (Bos taurus, with an average weight of 520 ± 30 kg and 480 ± 182 kg, respectively, with rumen cannula, over experimental design with two 3 x 3 Latin squares in a 3 x 2 factorial arrangement, with the absence or presence of additives: ionophore or probiotic and two species, were used. The internal flow indicator of fecal dry matter (DM was the acid insoluble ash. DM, crude protein (CP and neutral detergent fiber (NDF ruminal degradability of Tifton 85 hay was conducted for cattle and buffaloes. A diet containing probiotics had higher dry matter and organic matter digestibility in buffalo and cattle, indicating a good performance in bulky diets. The potential and effective dry matter degradability in diet with probiotic in buffaloes, were smaller than diet with ionophore, suggesting that there was a better digestion of nutrients in the intestine of these animals. The potential and effective degradability of neutral detergent fiber and crude protein in the diet containing ionophores were superior than diet containing probiotic. Buffaloes showed higher capacity of dry matter and fiber digestion than cattle.

  8. Tuning the self-assembly of the bioactive dipeptide L-carnosine by incorporation of a bulky aromatic substituent.

    Science.gov (United States)

    Castelletto, V; Cheng, G; Greenland, B W; Hamley, I W; Harris, P J F

    2011-03-15

    The dipeptide L-carnosine has a number of important biological properties. Here, we explore the effect of attachment of a bulky hydrophobic aromatic unit, Fmoc [N-(fluorenyl-9-methoxycarbonyl)] on the self-assembly of Fmoc-L-carnosine, i.e., Fmoc-β-alanine-histidine (Fmoc-βAH). It is shown that Fmoc-βAH forms well-defined amyloid fibrils containing β sheets above a critical aggregation concentration, which is determined from pyrene and ThT fluorescence experiments. Twisted fibrils were imaged by cryogenic transmission electron microscopy. The zinc-binding properties of Fmoc-βAH were investigated by FTIR and Raman spectroscopy since the formation of metal ion complexes with the histidine residue in carnosine is well-known, and important to its biological roles. Observed changes in the spectra may reflect differences in the packing of the Fmoc-dipeptides due to electrostatic interactions. Cryo-TEM shows that this leads to changes in the fibril morphology. Hydrogelation is also induced by addition of an appropriate concentration of zinc ions. Our work shows that the Fmoc motif can be employed to drive the self-assembly of carnosine into amyloid fibrils. PMID:21338121

  9. 1H MAS NMR characterization of hydrogen over silica-supported rhodium catalyst

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Hydrogen species in both SiO2 and Rh/SiO2 catalysts pretreated indifferent atmospheres (H2, O2, helium or air) at different temperatures (773 or 973 K) were investigated by means of 1H MAS NMR. In SiO2 and O2-pretreated catalysts, a series of downfield signals at ~7.0, 3.8-4.0, 2.0 and 1.5-1.0 were detected. The first two signals can be attributed to strongly adsorbed and physisorbed water and the others to terminal silanol (SiOH) and SiOH under the screening of oxygen vacancies in SiO2 lattice, respectively. Besides the above signals, both upfield signal at ~-110 and downfield signals at 3.0 and 0.0 were also detected in H2-pretreated catalyst, respectively. The upfield signal at ~-110 originated from the dissociative adsorption of H2 over rhodium and was found to consist of both the contributions of reversible and irreversible hydrogen. There also probably existed another dissociatively adsorbed hydrogen over rhodium, which was known to be b hydrogen and in a unique form of "delocalized hydrogen". It was presumed that the b hydrogen had an upfield shift of ca. -20- -50, though its 1H NMR signals, which, having been masked by the spinning sidebands of Si-OH, failed to be directly detected out. The downfield signal at 3.0 was assigned to spillover hydrogen weakly bound by the bridge oxygen of SiO2. Another downfield signal at 0.0 was assigned to hydrogen held in the oxygen vacancies of SiO2 (Si-H species), suffering from the screening of trapped electrons. Both the spillover hydrogen and the Si-H resulted from the migration of the reversible hydrogen and the b hydrogen from rhodium to SiO2 in the close vicinity. It was proved that the above migration of hydrogen was preferred to occur at higher temperature than at lower temperature.

  10. Gas insulated transmission line having low inductance intercalated sheath

    Science.gov (United States)

    Cookson, Alan H.

    1978-01-01

    A gas insulated transmission line including an outer sheath, an inner conductor disposed within the outer sheath, and an insulating gas between the inner conductor and the outer sheath. The outer sheath comprises an insulating tube having first and second ends, and having interior and exterior surfaces. A first electrically conducting foil is secured to the interior surface of the insulating tube, is spirally wound from one tube end to the second tube end, and has a plurality of overlapping turns. A second electrically conducting foil is secured to the exterior surface of the insulating tube, and is spirally wound in the opposite direction from the first electrically conducting foil. By winding the foils in opposite directions, the inductances within the intercalated sheath will cancel each other out.

  11. Water Intercalation for Seamless, Electrically Insulating, and Thermally Transparent Interfaces.

    Science.gov (United States)

    Wang, Yanlei; Xu, Zhiping

    2016-01-27

    The interface between functional nanostructures and host substrates is of pivotal importance in the design of their nanoelectronic applications because it conveys energy and information between the device and environment. We report here an interface-engineering approach to establish a seamless, electrically insulating, while thermally transparent interface between graphene and metal substrates by introducing water intercalation. Molecular dynamics simulations and first-principles calculations are performed to demonstrate this concept of design, showing that the presence of the interfacial water layer helps to unfold wrinkles formed in the graphene membrane, insulate the electronic coupling between graphene and the substrate, and elevate the interfacial thermal conductance. The findings here lay the ground for a new class of nanoelectronic setups through interface engineering, which could lead to significant improvement in the performance of nanodevices, such as the field-effect transistors. PMID:26720217

  12. An enhanced hydrogen adsorption enthalpy for fluoride intercalated graphite compounds.

    Science.gov (United States)

    Cheng, Hansong; Sha, Xianwei; Chen, Liang; Cooper, Alan C; Foo, Maw-Lin; Lau, Garret C; Bailey, Wade H; Pez, Guido P

    2009-12-16

    We present a combined theoretical and experimental study on H(2) physisorption in partially fluorinated graphite. This material, first predicted computationally using ab initio molecular dynamics simulation and subsequently synthesized and characterized experimentally, represents a novel class of "acceptor type" graphite intercalated compounds that exhibit significantly higher isosteric heat of adsorption for H(2) at near ambient temperatures than previously demonstrated for commonly available porous carbon-based materials. The unusually strong interaction arises from the semi-ionic nature of the C-F bonds. Although a high H(2) storage capacity (>4 wt %) at room temperature is predicted not to be feasible due to the low heat of adsorption, enhanced storage properties can be envisaged by doping the graphitic host with appropriate species to promote higher levels of charge transfer from graphene to F(-) anions. PMID:19928879

  13. Nanocomposite materials based on polyurethane intercalated into montmorillonite clay

    International Nuclear Information System (INIS)

    Polyurethane organoclay nanocomposites have been synthesized via in situ polymerization method. The organoclay has been prepared by intercalation of diethanolamine or triethanolamine into montmorillonite clay (MMT) through ion exchange process. The syntheses of polyurethane-organoclay hybrids were carried out by swelling the organoclay into different kinds of diols followed by addition of diisocyanate. The nanocomposites with dispersed structure of MMT was obtained as evidence by scanning electron microscope and X-ray diffraction (XRD). The results shows broaden with low intense and shift of the peak characteristic to d001 spacing to smaller 2θ and the MMT is dispersed homogeneously in the polymer matrix. Also, the TGA showed that the nanocomposites have higher decomposition temperature in comparison with the pristine polyurethane

  14. Maghemite Intercalated Montmorillonite as New Nanofillers for Photopolymers

    Directory of Open Access Journals (Sweden)

    Jocelyne Brendle

    2012-11-01

    Full Text Available In this work, maghemite intercalated montmorillonite (γFe2O3-MMT/polymer nanocomposites loaded with 1 or 2 wt.% of nanofillers were obtained by photopolymerization of difunctional acrylate monomers. The γFe2O3-MMT nanofillers were prepared by a new method based on the in situ formation of maghemite in the interlayer space of Fe-MMT using a three step process. X-ray diffraction (XRD, chemical analysis, TG/DTA and transmission electron microscopy (TEM characterization of these nanofillers indicated the efficiency of the synthesis. When following the kinetics of the photopolymerization of diacrylate-γFe2O3-MMT nanocomposites using FTIR spectroscopy no significant inhibition effect of the nanofillers was observed at a loading up to 2 wt.%. These innovative nanocomposites exhibit improved mechanical properties compared to the crude polymer.

  15. Dielectric properties of halloysite and halloysite-formamide intercalate

    Science.gov (United States)

    Adamczyk, M.; Rok, M.; Wolny, A.; Orzechowski, K.

    2014-01-01

    Due to a high increase in electromagnetic pollution, the protection from non-ionizing electromagnetic radiation (EMR) represents an important problem of contemporary environmental science. We are searching for natural materials with the potential for EMR screening. We have discovered that hydro-halloysite has interesting properties as an EMR absorber. Unfortunately, it is a very unstable material. Drying it for even a short period of time leads to the loss of desired properties. In the paper, we have demonstrated that the intercalation of halloysite (the process of introducing guest molecules into the mineral structure) makes it possible to recover the ability to absorb an electromagnetic wave and obtain a promising material for electromagnetic field shielding applications.

  16. 16 CFR 23.7 - Misuse of the words “platinum,” “iridium,” “palladium,” “ruthenium,” “rhodium,” and “osmium.”

    Science.gov (United States)

    2010-01-01

    ... § 23.7 Misuse of the words “platinum,” “iridium,” “palladium,” “ruthenium,” “rhodium,” and “osmium.” (a) It is unfair or deceptive to use the words “platinum,” “iridium,” “palladium,” “ruthenium,” “rhodium... Platinum, Iridium, Palladium, Ruthenium, Rhodium, and Osmium. (b) The following are examples of markings...

  17. Advantages of GPU technology in DFT calculations of intercalated graphene

    Science.gov (United States)

    Pešić, J.; Gajić, R.

    2014-09-01

    Over the past few years, the expansion of general-purpose graphic-processing unit (GPGPU) technology has had a great impact on computational science. GPGPU is the utilization of a graphics-processing unit (GPU) to perform calculations in applications usually handled by the central processing unit (CPU). Use of GPGPUs as a way to increase computational power in the material sciences has significantly decreased computational costs in already highly demanding calculations. A level of the acceleration and parallelization depends on the problem itself. Some problems can benefit from GPU acceleration and parallelization, such as the finite-difference time-domain algorithm (FTDT) and density-functional theory (DFT), while others cannot take advantage of these modern technologies. A number of GPU-supported applications had emerged in the past several years (www.nvidia.com/object/gpu-applications.html). Quantum Espresso (QE) is reported as an integrated suite of open source computer codes for electronic-structure calculations and materials modeling at the nano-scale. It is based on DFT, the use of a plane-waves basis and a pseudopotential approach. Since the QE 5.0 version, it has been implemented as a plug-in component for standard QE packages that allows exploiting the capabilities of Nvidia GPU graphic cards (www.qe-forge.org/gf/proj). In this study, we have examined the impact of the usage of GPU acceleration and parallelization on the numerical performance of DFT calculations. Graphene has been attracting attention worldwide and has already shown some remarkable properties. We have studied an intercalated graphene, using the QE package PHonon, which employs GPU. The term ‘intercalation’ refers to a process whereby foreign adatoms are inserted onto a graphene lattice. In addition, by intercalating different atoms between graphene layers, it is possible to tune their physical properties. Our experiments have shown there are benefits from using GPUs, and we reached an

  18. Advantages of GPU technology in DFT calculations of intercalated graphene

    International Nuclear Information System (INIS)

    Over the past few years, the expansion of general-purpose graphic-processing unit (GPGPU) technology has had a great impact on computational science. GPGPU is the utilization of a graphics-processing unit (GPU) to perform calculations in applications usually handled by the central processing unit (CPU). Use of GPGPUs as a way to increase computational power in the material sciences has significantly decreased computational costs in already highly demanding calculations. A level of the acceleration and parallelization depends on the problem itself. Some problems can benefit from GPU acceleration and parallelization, such as the finite-difference time-domain algorithm (FTDT) and density-functional theory (DFT), while others cannot take advantage of these modern technologies. A number of GPU-supported applications had emerged in the past several years (www.nvidia.com/object/gpu-applications.html). Quantum Espresso (QE) is reported as an integrated suite of open source computer codes for electronic-structure calculations and materials modeling at the nano-scale. It is based on DFT, the use of a plane-waves basis and a pseudopotential approach. Since the QE 5.0 version, it has been implemented as a plug-in component for standard QE packages that allows exploiting the capabilities of Nvidia GPU graphic cards (www.qe-forge.org/gf/proj). In this study, we have examined the impact of the usage of GPU acceleration and parallelization on the numerical performance of DFT calculations. Graphene has been attracting attention worldwide and has already shown some remarkable properties. We have studied an intercalated graphene, using the QE package PHonon, which employs GPU. The term ‘intercalation’ refers to a process whereby foreign adatoms are inserted onto a graphene lattice. In addition, by intercalating different atoms between graphene layers, it is possible to tune their physical properties. Our experiments have shown there are benefits from using GPUs, and we reached an

  19. Strong DNA deformation required for extremely slow DNA threading intercalation by a binuclear ruthenium complex

    Science.gov (United States)

    Almaqwashi, Ali A.; Paramanathan, Thayaparan; Lincoln, Per; Rouzina, Ioulia; Westerlund, Fredrik; Williams, Mark C.

    2014-01-01

    DNA intercalation by threading is expected to yield high affinity and slow dissociation, properties desirable for DNA-targeted therapeutics. To measure these properties, we utilize single molecule DNA stretching to quantify both the binding affinity and the force-dependent threading intercalation kinetics of the binuclear ruthenium complex Δ,Δ-[μ‐bidppz‐(phen)4Ru2]4+ (Δ,Δ-P). We measure the DNA elongation at a range of constant stretching forces using optical tweezers, allowing direct characterization of the intercalation kinetics as well as the amount intercalated at equilibrium. Higher forces exponentially facilitate the intercalative binding, leading to a profound decrease in the binding site size that results in one ligand intercalated at almost every DNA base stack. The zero force Δ,Δ-P intercalation Kd is 44 nM, 25-fold stronger than the analogous mono-nuclear ligand (Δ-P). The force-dependent kinetics analysis reveals a mechanism that requires DNA elongation of 0.33 nm for association, relaxation to an equilibrium elongation of 0.19 nm, and an additional elongation of 0.14 nm from the equilibrium state for dissociation. In cells, a molecule with binding properties similar to Δ,Δ-P may rapidly bind DNA destabilized by enzymes during replication or transcription, but upon enzyme dissociation it is predicted to remain intercalated for several hours, thereby interfering with essential biological processes. PMID:25245944

  20. Fabrication and Resistivity of IBr Intercalated Vapor-Grown Carbon Fiber Composites

    Science.gov (United States)

    Gaier, James R.; Smith, Jaclyn M.; Gahl, Gregory K.; Stevens, Eric C.; Gaier, Elizabeth M.

    1998-01-01

    Composites using vapor-crown carbon fibers (VGCF), the most conductive of the carbon fiber types, are attractive for applications where low density, high strength, and at least moderate conductivity are required, such as electromagnetic interference shielding covers for spacecraft. The conductivity can be enhanced another order of magnitude by intercalation of the VGCF. If a high Z intercalate is used, the protection of components from ionizing radiation can be enhanced also. Thus, the intercalation of VGCF with IBr is reported. Since composite testing is required to verify properties, the intercalation reaction optimization, stability of the intercalation compound, scale-up of the intercalation reaction, composite fabrication, and resistivity of the resulting composites is also reported. The optimum conditions for low resistivity and uniformity for the scaled up reaction (20-30 g of product) were 114 C for at least 72 hr, yielding a fiber with a resistivity of 8.7+/-2 micro-Omega-cm. The thermal stability of these fibers was poor, with degradation occurring at temperatures as low as 40 C in air, though they were insensitive to water vapor. Composite resistivity was 20-30 micro-Omega-cm, as measured by contactless conductivity measurements, about a factor of five higher than would be expected from a simple rule of mixtures. The addition of 1.0 percent Br2, intercalated microfibers increased the resistivity of the composites by more than 20 percent.

  1. Synthesis and characterization of montmorillonite clay intercalated with molecular magnetic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Martins, Marcel G.; Martins, Daniel O.T.A.; Carvalho, Beatriz L.C. de [Instituto de Química, Universidade Federal Fluminense, Niterói, RJ 24.020–150 (Brazil); Mercante, Luiza A. [Laboratório Nacional de Nanotecnologia para o Agronegócio (LNNA), Embrapa Instrumentação, São Carlos, SP 13560 970 (Brazil); Soriano, Stéphane [Instituto de Física, Universidade Federal Fluminense, Niterói, RJ 24.210 346 (Brazil); Andruh, Marius [Inorganic Chemistry Laboratory, Faculty of Chemistry, University of Bucharest, Str. Dumbrava Rosie nr. 23, Bucharest (Romania); Vieira, Méri D., E-mail: gqimeri@vm.uff.br [Instituto de Química, Universidade Federal Fluminense, Niterói, RJ 24.020–150 (Brazil); Vaz, Maria G.F., E-mail: mariavaz@vm.uff.br [Instituto de Química, Universidade Federal Fluminense, Niterói, RJ 24.020–150 (Brazil)

    2015-08-15

    In this work montmorillonite (MMT) clay, whose matrix was modified with an ammonium salt (hexadecyltrimethylammonium bromide – CTAB), was employed as an inorganic host for the intercalation of three different molecular magnetic compounds through ion exchange: a nitronyl nitroxide derivative 2-[4-(N-ethyl)-pyridinium]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (p-EtRad{sup +}) and two binuclear coordination compounds, [Ni(valpn)Ln]{sup 3+}, where H{sub 2}valpn stands for 1,3-propanediyl-bis(2-iminomethylene-6-methoxy-phenol), and Ln=Gd{sup III}; Dy{sup III}. The pristine MMT and the intercalated materials were characterized by X-ray powder diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and magnetic measurements. The X-ray diffraction data analysis showed an increase of the interlamellar space of the intercalated MMT, indicating the intercalation of the magnetic compounds. Furthermore, the magnetic properties of the hybrid compounds were investigated, showing similar behavior as the pure magnetic guest species. - Graphical abstract: Montmorillonite clay was employed as inorganic host for the intercalation of three different molecular magnetic compounds through ion exchange - Highlights: • Montmorillonite was employed as a host material. • Three molecular magnetic compounds were intercalated through ion exchange. • The compounds were successful intercalated maintaining the layered structure. • The hybrid materials exhibited similar magnetic behavior as the pure magnetic guest.

  2. Synthesis and characterization of montmorillonite clay intercalated with molecular magnetic compounds

    International Nuclear Information System (INIS)

    In this work montmorillonite (MMT) clay, whose matrix was modified with an ammonium salt (hexadecyltrimethylammonium bromide – CTAB), was employed as an inorganic host for the intercalation of three different molecular magnetic compounds through ion exchange: a nitronyl nitroxide derivative 2-[4-(N-ethyl)-pyridinium]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (p-EtRad+) and two binuclear coordination compounds, [Ni(valpn)Ln]3+, where H2valpn stands for 1,3-propanediyl-bis(2-iminomethylene-6-methoxy-phenol), and Ln=GdIII; DyIII. The pristine MMT and the intercalated materials were characterized by X-ray powder diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and magnetic measurements. The X-ray diffraction data analysis showed an increase of the interlamellar space of the intercalated MMT, indicating the intercalation of the magnetic compounds. Furthermore, the magnetic properties of the hybrid compounds were investigated, showing similar behavior as the pure magnetic guest species. - Graphical abstract: Montmorillonite clay was employed as inorganic host for the intercalation of three different molecular magnetic compounds through ion exchange - Highlights: • Montmorillonite was employed as a host material. • Three molecular magnetic compounds were intercalated through ion exchange. • The compounds were successful intercalated maintaining the layered structure. • The hybrid materials exhibited similar magnetic behavior as the pure magnetic guest

  3. Electronic and transmission properties of magnetotunnel junctions of cobalt/iron intercalated bilayer two dimensional sheets

    Energy Technology Data Exchange (ETDEWEB)

    Jiao, N.; Xie, M.D. [Department of Physics, Xiangtan University, Xiangtan 411105, Hunan (China); Zhou, P. [Hunan Provincial Key Laboratory of Thin Film Materials and Devices, School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105 (China); Sun, L.Z., E-mail: lzsun@xtu.edu.cn [Hunan Provincial Key Laboratory of Thin Film Materials and Devices, School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105 (China)

    2015-10-23

    Highlights: • The TMR ratio reaches 169% for Co intercalated Ni|bi-GBN|Ni MTJs. • The TMR ratio reaches 173% for Fe intercalated Ni|bi-GBN|Ni MTJs. • Intercalated Co/Fe effectively modulates the spin filtering of bilayer systems. - Abstract: Density functional theory and the nonequilibrium Green's function method are used to study the electronic properties and tunneling magnetoresistance (TMR) of magnetotunnel junctions (MTJs) based on Co/Fe intercalated bilayer graphene (bi-Gr), bilayer hexagonal boron nitride (bi-h-BN), and bilayer Gr-h-BN (bi-GBN). The spin-polarized bands around the Fermi energy of the two dimensional bilayer sheets are modulated by the intercalated cobalt. The TMR ratio reaches 169.94% and 173.00% for cobalt and iron intercalated Ni|bi-GBN|Ni MTJs, respectively. We observe that the Co/Fe intercalated bi-GBN is a promising candidate as a spacer in MTJs for spintronics.

  4. Carbon dioxide intercalation in Na-fluorohectorite clay at near-ambient conditions

    Science.gov (United States)

    Fossum, Jon Otto; Hemmen, Henrik; Rolseth, Erlend G.; Fonseca, Davi; Lindbo Hansen, Elisabeth; Plivelic, Tomas

    2012-02-01

    A molecular dynamics study by Cygan et al.[1] shows the possibility of intercalation and retention of CO2 in smectite clays at 37 ^oC and 200 bar, which suggests that clay minerals may prove suitable for carbon capture and carbon dioxide sequestration. In this work we show from x-ray diffraction measurements that gaseous CO2 intercalates into the interlayer space of the synthetic smectite clay Na-fluorohectorite. The mean interlayer distance of the clay when CO2 is intercalated is 12.5 å at -20 C and 15 bar. The magnitude of the expansion of the interlayer upon intercalation is indistinguishable from that of the dehydrated-monohydrated intercalation of H2O, but this possibility is ruled out by careful repeating the measurements exposing the clay to nitrogen gas. The dynamics of the CO2 intercalation process displays a higher intercalation rate at increased pressure, and the rate is several orders of magnitude slower than that of water or vapor at ambient pressure and temperature.[4pt] [1] Cygan, R. T.; Romanov, V. N.; Myshakin, E. M. Natural materials for carbon capture; Techincal report SAND2010-7217; Sandia National Laboratories: Albuquerque, New Mexico, November, 2010.

  5. Electronic and transmission properties of magnetotunnel junctions of cobalt/iron intercalated bilayer two dimensional sheets

    International Nuclear Information System (INIS)

    Highlights: • The TMR ratio reaches 169% for Co intercalated Ni|bi-GBN|Ni MTJs. • The TMR ratio reaches 173% for Fe intercalated Ni|bi-GBN|Ni MTJs. • Intercalated Co/Fe effectively modulates the spin filtering of bilayer systems. - Abstract: Density functional theory and the nonequilibrium Green's function method are used to study the electronic properties and tunneling magnetoresistance (TMR) of magnetotunnel junctions (MTJs) based on Co/Fe intercalated bilayer graphene (bi-Gr), bilayer hexagonal boron nitride (bi-h-BN), and bilayer Gr-h-BN (bi-GBN). The spin-polarized bands around the Fermi energy of the two dimensional bilayer sheets are modulated by the intercalated cobalt. The TMR ratio reaches 169.94% and 173.00% for cobalt and iron intercalated Ni|bi-GBN|Ni MTJs, respectively. We observe that the Co/Fe intercalated bi-GBN is a promising candidate as a spacer in MTJs for spintronics

  6. Thermodynamic Complexing of Monocyclopentadienylferrum (II) Intercalates with Double-Walled Carbon Nanotubes.

    Science.gov (United States)

    Мykhailenko, О V; Prylutskyy, Yu I; Кomarov, І V; Strungar, А V

    2016-12-01

    By employing the methods of molecular mechanics, semi-empirical quantum-chemical РМ3 and Monte-Carlo, the positioning of monocyclopentadienylferrum (II) molecules in double-walled (5,5)@(10,10) carbon nanotubes (CNT) depending on their concentration and temperature has been studied. The molecules have been found out to form stable bonds with CNT walls, with a tendency between intercalate stability and the CNT structure. The temperature growth (over ~500 K) causes gradual bond ruining followed by extrusion of interwall intercalate. Further temperature increase up to 600-700 K is characterised with intercalate external surface desorption, stabilising the whole system and keeping the interwall intercalate only. The CNT's UV-spectrum (5,5)@(10,10) depending on the intercalate concentration and association constant of the "double-walled CNT-intercalate" system have been calculated. A combination of unique optical, electrical and magnetic behaviour of cyclopentadienyl complexes with their ability to form high-stable intercalate with CNT opens a prospect of their applying in nanotechnology. PMID:26951128

  7. Cerium Oxide Nanoclusters on Graphene/Ru(0001): Intercalation of Oxygen via Spillover.

    Science.gov (United States)

    Novotny, Zbynek; Netzer, Falko P; Dohnálek, Zdenek

    2015-08-25

    Cerium oxide is an important catalytic material known for its ability to store and release oxygen, and as such, it has been used in a range of applications, both as an active catalyst and as a catalyst support. Using scanning tunneling microscopy and Auger electron spectroscopy, we investigated oxygen interactions with CeOx nanoclusters on a complete graphene monolayer-covered Ru(0001) surface at elevated temperatures (600-725 K). Under oxidizing conditions (PO2 = 1 × 10(-7) Torr), oxygen intercalation under the graphene layer is observed. Time dependent studies demonstrate that the intercalation proceeds via spillover of oxygen from CeOx nanoclusters through the graphene (Gr) layer onto the Ru(0001) substrate and extends until the Gr layer is completely intercalated. Atomically resolved images further show that oxygen forms a p(2 × 1) structure underneath the Gr monolayer. Temperature dependent studies yield an apparent kinetic barrier for the intercalation of 1.21 eV. This value correlates well with the theoretically determined value for the reduction of small CeO2 clusters reported previously. At higher temperatures, the intercalation is followed by a slower etching of the intercalated graphene (apparent barrier of 1.60 eV). Vacuum annealing of the intercalated Gr leads to the formation of carbon monoxide, causing etching of the graphene film, demonstrating that the spillover of oxygen is not reversible. In agreement with previous studies, no intercalation is observed on a complete graphene monolayer without CeOx clusters, even in the presence of a large number of point defects. These studies demonstrate that the easily reducible CeOx clusters act as intercalation gateways capable of efficiently delivering oxygen underneath the graphene layer. PMID:26230753

  8. Screen-Printed Carbon Electrodes Modified by Rhodium Dioxide and Glucose Dehydrogenase

    Directory of Open Access Journals (Sweden)

    Vojtěch Polan

    2010-01-01

    Full Text Available The described glucose biosensor is based on a screen-printed carbon electrode (SPCE modified by rhodium dioxide, which functions as a mediator. The electrode is further modified by the enzyme glucose dehydrogenase, which is immobilized on the electrode's surface through electropolymerization with m-phenylenediamine. The enzyme biosensor was optimized and tested in model glucose samples. The biosensor showed a linear range of 500–5000 mg L−1 of glucose with a detection limit of 210 mg L−1 (established as 3σ and response time of 39 s. When compared with similar glucose biosensors based on glucose oxidase, the main advantage is that neither ascorbic and uric acids nor paracetamol interfere measurements with this biosensor at selected potentials.

  9. Mapping of the radiation field of a mammography equipment using molybdenum and rhodium filters

    Energy Technology Data Exchange (ETDEWEB)

    Barreira, Jacqueline S.; Campos, Daniela; Vivolo, Vitor, E-mail: jacsales@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2014-07-01

    The use of X rays for diagnostic radiology is very common and important to Medicine, including mammographic diagnosis focusing decreasing of the doses applied to the patients and preserving high quality of the diagnostic image. A quality control program of the irradiation systems it is very necessary. The Instruments Calibration Laboratory (LCI) of IPEN perform calibration in dosemeters used in radiation dosimetry (in diagnostic radiology) for many years. The objective of that paper is determining the point of greatest intensity of the beam issued by the mammography equipment. Exposures were made with filters Rhodium and Molybdenum. That mapping is important before applied a routine quality control program of the mammography equipment and the calibration of instruments in the diagnosis. (author)

  10. Rhodium and ruthenium tetracarboxylate nitrosyl complexes: electronic structure and metal-metal bond

    International Nuclear Information System (INIS)

    The electronic structure of the tetracarboxylates M2(μ-O2CH)4, M2(μ-O2CH)4(L)2 (M = Ru, Rh; L= H2O, NO) was analyzed by the density functional theory with full geometry optimization. The inclusion of nitrogen oxide orbitals into the molecular orbitals forming the metal-metal bond affects all of the main characteristics of this bond and the concomitant properties. In the case of rhodium tetracarboxylates, one can consider destruction of the Rh-Rh covalent σ-bond and reorientation of two electrons from the internal region of the Rh2(μ-O2CH)4 core to the outside, toward the axial ligands to give Rh-N covalent bonds. The axial coordination of nitrogen oxide in Ru2(μ-O2CR)4 is accompanied by destruction of the metal-metal π-bond

  11. Synergistic effects of hydrogen plasma exposure, pulsed laser heating and temperature on rhodium surfaces

    International Nuclear Information System (INIS)

    The combined effect of hydrogen plasma exposure and surface heating, either continuous or by short laser pulses (5 ns), on the surface morphology of rhodium layers has been studied. Investigations were performed by reflectivity measurements, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and atomic force microscope (AFM). While surfaces exposed at room temperature exhibit little modifications, strong surface changes are observed for surface temperatures higher than 250 °C. At 500 °C, the plasma exposed surface exhibits a nanoscale structure (50–100 nm) with a high level of porosity and a low reflectivity. Additional laser irradiation of the surface strongly enhances the observed surface damage. Localized surface melting is observed with craters extending deep into the substrate together with a dense network of voids.

  12. New data on some short-lived isotopes of ruthenium and rhodium

    International Nuclear Information System (INIS)

    Ru and Rd isotopes with mass numbers 107 and 108 and 109Rh, has been obtained from fission products. 107 Ru has also been prepared by the nuclear process 110Pd (n,α) 107 Ru. Beta and gamma energies of these nuclides have been studied spectropolarimetry and the gamma lines found for 107 Ru and 108Ru ( and daughter) have been very useful for the precise determination of their half-lives. 109Rh has been identified through its daughter 109Pd in the mixture of rhodium isotopes from fission products. Irradiation of natural palladium with fast neutrons has lead to an activity that may only be attributed to 110rh. Neither its half life nor its decay energy have been possible to determine accurately. (Author) 1 refs

  13. Dimerisation, rhodium complex formation and rearrangements of N-heterocyclic carbenes of indazoles

    Directory of Open Access Journals (Sweden)

    Zong Guan

    2014-04-01

    Full Text Available Deprotonation of indazolium salts at low temperatures gives N-heterocyclic carbenes of indazoles (indazol-3-ylidenes which can be trapped as rhodium complexes (X-ray analysis. In the absence of Rh, the indazol-3-ylidenes spontaneously dimerize under ring cleavage of one of the N,N-bonds and ring closure to an indazole–indole spiro compound which possesses an exocyclic imine group. The E/Z isomers of the imines can be separated by column chromatography when methanol is used as eluent. We present results of a single crystal X-ray analysis of one of the E-isomers, which equilibrate in solution as well as in the solid state. Heating of the indazole–indole spiro compounds results in the formation of quinazolines by a ring-cleavage/ring-closure sequence (X-ray analysis. Results of DFT calculations are presented.

  14. Determination of palladium, platinum and rhodium in geologic materials by fire assay and emission spectrography

    Science.gov (United States)

    Hapfty, J.; Riley, L.B.

    1968-01-01

    A method is described for the determination of palladium down to 4ppb (parts per billion, 109), platinum down to 10 ppb and rhodium down to 5 ppb in 15 g of sample. Fire-assay techniques are used to preconcentrate the platinum metals into a gold bead, then the bead is dissolved in aqua regia and diluted to volume with 1M hydrochloric acid. The solution is analysed by optical emission spectrography of the residue from 200 ??l of it evaporated on a pair of flat-top graphite electrodes. This method requires much less sample handling than most published methods for these elements. Data are presented for G-1, W-1, and six new standard rocks of the U.S. Geological Survey. The values for palladium in W-1 are in reasonable agreement with previously published data. ?? 1968.

  15. Production of Palladium-103 (103Pd) from a thin rhodium foil target - Improved cooling concept

    International Nuclear Information System (INIS)

    Palladium-103 (103Pd) is one of the commonly used radioisotopes for prostate cancer treatment. The current irradiation technique used to produce this radioisotope suffers from several serious inherent drawbacks, of which one is the low beam current due to cooling limitation and the other is the electroplating process used to prepare the target. A liquid-metal jet impingement target cooling system developed at Soreq NRC demonstrated recently a cooling capacity of 8.4 kW/cm2 while the pressure of the cooling liquid on the target back was less than 1 bar. The latter value implies that the target can be made very thin and that the copper back-plate might be removed. Hence, we propose a new target design based on the use of a thin rhodium foil directly cooled by a liquid-metal such as gallium

  16. Electrochemical and mass variation behaviour of rhodium oxide electrodes prepared by the polymeric precursor method

    International Nuclear Information System (INIS)

    This paper describes an investigation of the charging processes of Rh2O3 electrodes in acidic medium using Electrochemical Quartz Crystal Microbalance. The Rh2O3 was prepared by the Pechini method. The microstructural characterization of the rhodium oxide was performed using Scanning Electron Microscopy and the structure was determined by X-ray diffraction. The Rh2O3 oxidizes at potentials higher than 0.8 V. A mass loss of 60 ng was observed during the anodic sweep. The same amount is gained during the cathodic sweep indicating that the process is reversible. From the mass versus charge plots a slope of 8.5 g mol-1is calculated. Considering a process that involves a two-electron transfer, the oxidation of Rh2O3 to RhO2 with the loss of a water molecule (18 g mol-1) is proposed

  17. Rhodium in-core detector sensitivity depletion, cycles 2 to 4. Interim report

    International Nuclear Information System (INIS)

    Sensitivity depletion of two rhodium (Rh) self-powered neutron detectors (SPNDs) has been measured since July 1976 at the Oconee 2 pressurized water reactor (PWR). The detectors were positioned inside the reactor core throughout the measurement period. Depletion has been determined as a function of electric charge expended (released) by each detector. The goal of the project is the empirical definition of the depletion characteristics over the operating life-time of the Rh detector. Results to data show that the sensitivity depletion rate of the Rh detector in the PWR is highly linear with charge released from the detector. In contrast to preliminary observations reported earlier, there appears to be no effect on the depletion rate that is traceable to the beginning-of-cycle burnup of the fuel assembly in which the Rh detectors are located

  18. Hydroformylation and kinetics of 1-hexene over ruthenium, cobalt and rhodium zerolite catalysts

    International Nuclear Information System (INIS)

    In this paper, six kinds of catalysts were prepared by cation exchange with rhodium, ruthenium and cobalt chloropentaamino dichoride and zeolites. Effects such as support materials, PPH3 to metal ratio, reaction temperature, total pressure, H2/CO ratio, reaction time and solvents have been investigated in an autoclave. The most favorable results of 1-hexene hydroformylation were obtained in the temperature range 100-150 degrees C at a pressure of 5.0MPa (H2/CO=1:1) and the addition of free PPh3. The bimetallic catalysts showed high catalytic activing for hydroformylation because of the synergistic effect of bimetallic systems. This paper reports the results of experiments and catalysts characterization by means of IR and XRD spectroscopy

  19. Tunable Cascade Reactions of Alkynols with Alkynes under Combined Sc(OTf)3 and Rhodium Catalysis.

    Science.gov (United States)

    Li, Deng Yuan; Chen, Hao Jie; Liu, Pei Nian

    2016-01-01

    Two tunable cascade reactions of alkynols and alkynes have been developed by combining Sc(OTf)3 and rhodium catalysis. In the absence of H2O, an endo-cycloisomerization/C-H activation cascade reaction provided 2,3-dihydronaphtho[1,2-b]furans in good to high yields. In the presence of H2O, the product of alkynol hydration underwent an addition/C-H activation cascade reaction with an alkyne, which led to the formation of 4,5-dihydro-3H-spiro[furan-2,1'-isochromene] derivatives in good yields under mild reaction conditions. Mechanistic studies of the cascade reactions indicated that the rate-determining step involves C-H bond cleavage and that the hydration of the alkynol plays a key role in switching between the two reaction pathways. PMID:26531133

  20. Scanning tunneling microscopy studies of organic monolayers adsorbed on the rhodium(111) crystal surface

    Energy Technology Data Exchange (ETDEWEB)

    Cernota, Paul D.

    1999-08-01

    Scanning Tunneling Microscopy studies were carried out on ordered overlayers on the (111) surface of rhodium. These adsorbates include carbon monoxide (CO), cyclohexane, cyclohexene, 1,4-cyclohexadiene, para-xylene, and meta-xylene. Coadsorbate systems included: CO with ethylidyne, CO with para- and meta-xylene, and para-xylene with meta-xylene. In the case of CO, the structure of the low coverage (2x2) overlayer has been observed. The symmetry of the unit cell in this layer suggests that the CO is adsorbed in the 3-fold hollow sites. There were also two higher coverage surface structures with ({radical}7x{radical}7) unit cells. One of these is composed of trimers of CO and has three CO molecules in each unit cell. The other structure has an additional CO molecule, making a total of four. This extra CO sits on a top site.

  1. Screen-printed carbon electrodes modified by rhodium dioxide and glucose dehydrogenase.

    Science.gov (United States)

    Polan, Vojtěch; Soukup, Jan; Vytřas, Karel

    2011-01-01

    The described glucose biosensor is based on a screen-printed carbon electrode (SPCE) modified by rhodium dioxide, which functions as a mediator. The electrode is further modified by the enzyme glucose dehydrogenase, which is immobilized on the electrode's surface through electropolymerization with m-phenylenediamine. The enzyme biosensor was optimized and tested in model glucose samples. The biosensor showed a linear range of 500-5000 mg L(-1) of glucose with a detection limit of 210 mg L(-1) (established as 3σ) and response time of 39 s. When compared with similar glucose biosensors based on glucose oxidase, the main advantage is that neither ascorbic and uric acids nor paracetamol interfere measurements with this biosensor at selected potentials. PMID:21528113

  2. Optimization of Rhodium-Based Catalysts for Mixed Alcohol Synthesis – 2012 Progress Report

    Energy Technology Data Exchange (ETDEWEB)

    Gerber, Mark A.; Gray, Michel J.; Albrecht, Karl O.; Thompson, Becky L.

    2012-11-01

    Pacific Northwest National Laboratory has been conducting research to investigate the feasibility of producing mixed alcohols from biomass-derived synthesis gas (syngas). In recent years, this research has primarily involved the further development of catalysts containing rhodium and manganese based on the results of earlier catalyst screening tests. Testing continued in FY 2012 to further improve the Ir-promoted RhMn catalysts on both silica and carbon supports for producing mixed oxygenates from synthesis gas. This testing re-examined selected alternative silica and carbon supports to follow up on some uncertainties in the results with previous test results. Additional tests were conducted to further optimize the total and relative concentrations of Rh, Mn, and Ir, and to examine selected promoters and promoter combinations based on earlier results. To establish optimum operating conditions, the effects of the process pressure and the feed gas composition also were evaluated.

  3. Optimization of Rhodium-Based Catalysts for Mixed Alcohol Synthesis -- 2011 Progress Report

    Energy Technology Data Exchange (ETDEWEB)

    Gerber, Mark A.; Gray, Michel J.; Albrecht, Karl O.; Rummel, Becky L.

    2011-10-01

    Pacific Northwest National Laboratory has been conducting research to investigate the feasibility of producing mixed alcohols from biomass-derived synthesis gas (syngas). In recent years, this research has primarily involved the further development of catalysts containing rhodium and manganese based on the results of earlier catalyst screening tests. Research during FY 2011 continued to examine the performance of RhMn catalysts on alternative supports including selected zeolite, silica, and carbon supports. Catalyst optimization continued using both the Davisil 645 and Merck Grade 7734 silica supports. Research also was initiated in FY 2011, using the both Davisil 645 silica and Hyperion CS-02C-063 carbon supports, to evaluate the potential for further improving catalyst performance, through the addition of one or two additional metals as promoters to the catalysts containing Rh, Mn, and Ir.

  4. Enantioselective Rhodium-Catalyzed Cycloisomerization of (E)-1,6-Enynes.

    Science.gov (United States)

    Deng, Xu; Ni, Shao-Fei; Han, Zheng-Yu; Guan, Yu-Qing; Lv, Hui; Dang, Li; Zhang, Xu-Mu

    2016-05-17

    An enantioselective rhodium(I)-catalyzed cycloisomerization reaction of challenging (E)-1,6-enynes is reported. This novel process enables (E)-1,6-enynes with a wide range of functionalities, including nitrogen-, oxygen-, and carbon-tethered (E)-1,6-enynes, to undergo cycloisomerization with excellent enantioselectivity, in a high-yielding and operationally simple manner. Moreover, this Rh(I) -diphosphane catalytic system also exhibited superior reactivity and enantioselectivity for (Z)-1,6-enynes. A rationale for the striking reactivity difference between (E)- and (Z)-1,6-enynes using Rh(I) -BINAP and Rh(I) -TangPhos is outlined using DFT studies to provide the necessary insight for the design of new catalyst systems and the application to synthesis. PMID:27061132

  5. Rhodium-catalyzed acyloxy migration of propargylic esters in cycloadditions, inspiration from the recent "gold rush".

    Science.gov (United States)

    Shu, Xing-Zhong; Shu, Dongxu; Schienebeck, Casi M; Tang, Weiping

    2012-12-01

    Transition metal-catalyzed acyloxy migration of propargylic esters offers versatile entries to allene and vinyl carbene intermediates for various fascinating subsequent transformations. Most π-acidic metals (e.g. gold and platinum) are capable of facilitating these acyloxy migration events. However, very few of these processes involve redox chemistry, which are well-known for most other transition metals such as rhodium. The coupling of acyloxy migration of propargylic esters with oxidative addition, migratory insertion, and reductive elimination may lead to ample new opportunities for the design of new reactions. This tutorial review summarizes recent developments in Rh-catalyzed 1,3- and 1,2-acyloxy migration of propargylic esters in a number of cycloaddition reactions. Related Au- and Pt-catalyzed cycloadditions involving acyloxy migration are also discussed. PMID:22895533

  6. The DNA glycosylase AlkD uses a non-base-flipping mechanism to excise bulky lesions

    Science.gov (United States)

    Mullins, Elwood A.; Shi, Rongxin; Parsons, Zachary D.; Yuen, Philip K.; David, Sheila S.; Igarashi, Yasuhiro; Eichman, Brandt F.

    2015-11-01

    Threats to genomic integrity arising from DNA damage are mitigated by DNA glycosylases, which initiate the base excision repair pathway by locating and excising aberrant nucleobases. How these enzymes find small modifications within the genome is a current area of intensive research. A hallmark of these and other DNA repair enzymes is their use of base flipping to sequester modified nucleotides from the DNA helix and into an active site pocket. Consequently, base flipping is generally regarded as an essential aspect of lesion recognition and a necessary precursor to base excision. Here we present the first, to our knowledge, DNA glycosylase mechanism that does not require base flipping for either binding or catalysis. Using the DNA glycosylase AlkD from Bacillus cereus, we crystallographically monitored excision of an alkylpurine substrate as a function of time, and reconstructed the steps along the reaction coordinate through structures representing substrate, intermediate and product complexes. Instead of directly interacting with the damaged nucleobase, AlkD recognizes aberrant base pairs through interactions with the phosphoribose backbone, while the lesion remains stacked in the DNA duplex. Quantum mechanical calculations revealed that these contacts include catalytic charge-dipole and CH-π interactions that preferentially stabilize the transition state. We show in vitro and in vivo how this unique means of recognition and catalysis enables AlkD to repair large adducts formed by yatakemycin, a member of the duocarmycin family of antimicrobial natural products exploited in bacterial warfare and chemotherapeutic trials. Bulky adducts of this or any type are not excised by DNA glycosylases that use a traditional base-flipping mechanism. Hence, these findings represent a new model for DNA repair and provide insights into catalysis of base excision.

  7. Neutron scattering studies of hydrogen in potassium-graphite intercalates: Towards tunable graphite intercalates for hydrogen storage

    International Nuclear Information System (INIS)

    Low-temperature neutron scattering studies on the ternary graphite intercalation compounds KC24(H2)x, x=1,1.5 show low-energy excitations analogous to those seen in CsC24(H2)x and RbC24(H2)x, attributable to the rotational mode of the H2 split due to the crystal field of the graphene sheets. As in the Cs and Rb-doped systems the hydrogen in KC24(H2)x also occupies two sites. But no preferential population of sites was observed, implying that both sites fill at lower H2 concentration than in the Cs and Rb systems. Increasing c-lattice spacing by doping with deuterated ammonia has the effect of hindering the H2 adsorption, underlining the importance of an optimised graphite-charging regime to maximise hydrogen storage capability in these systems

  8. Synthesis of reduced graphene oxide intercalated ZnO quantum dots nanoballs for selective biosensing detection

    Science.gov (United States)

    Chen, Jing; Zhao, Minggang; Li, Yingchun; Fan, Sisi; Ding, Longjiang; Liang, Jingjing; Chen, Shougang

    2016-07-01

    ZnO quantum dots (QDs), reduced graphene oxide (rGO) and multi-walled carbon nanotubes (MWCNTs) are always used in sensors due to their excellent electrochemical characteristics. In this work, ZnO QDs were intercalated by rGO sheets with cross-linked MWCNTs to construct intercalation nanoballs. A MWCNTs/rGO/ZnO QDs 3D hierarchical architecture was fabricated on supporting Ni foam, which exhibited excellent mechanical, kinetic and electrochemical properties. The intercalation construction can introduce strong interfacial effects to improve the surface electronic state. The selectively determinate of uric acid, dopamine, and ascorbic acid by an electrode material using distinct applied potentials was realized.

  9. Room Temperature Ferromagnetism in InTe Layered Semiconductor Crystals Intercalated by Cobalt

    Directory of Open Access Journals (Sweden)

    V.B. Boledzyuk

    2015-03-01

    Full Text Available The magnetic properties of CoxInTe layered crystals electrochemically intercalated with cobalt in constant gradient magnetic field and the morphology of the van der Waals surfaces of layers of these crystals were studied. It was established that impurity clusters consisting of cobalt nanoparticles are formed in the intercalates under investigation on the van der Waals planes in the interlayer space. It was revealed that at room temperature the investigated CoxInTe intercalates exhibit magnetic properties characteristic for magnetically hard ferromagnetic materials.

  10. High voltage and high specific capacity dual intercalating electrode Li-ion batteries

    Science.gov (United States)

    West, William C. (Inventor); Blanco, Mario (Inventor)

    2010-01-01

    The present invention provides high capacity and high voltage Li-ion batteries that have a carbonaceous cathode and a nonaqueous electrolyte solution comprising LiF salt and an anion receptor that binds the fluoride ion. The batteries can comprise dual intercalating electrode Li ion batteries. Methods of the present invention use a cathode and electrode pair, wherein each of the electrodes reversibly intercalate ions provided by a LiF salt to make a high voltage and high specific capacity dual intercalating electrode Li-ion battery. The present methods and systems provide high-capacity batteries particularly useful in powering devices where minimizing battery mass is important.

  11. CO intercalation of graphene on Ir(111) in the millibar regime

    DEFF Research Database (Denmark)

    Arman, M.A.; Andersen, Mie; Granas, E.; Gerber, T.; Hammer, B.; Schnadt, J.; Andersen, J.N.; Michely, T.; Knudsen, J.

    2013-01-01

    Here we show that it is possible to intercalate CO under graphene grown on Ir(111) already at room temperature when CO pressures in the millibar regime are used. From the interplay of X-ray photoelectron spectroscopy and scanning tunneling microscopy we conclude that the intercalated CO adsorption...... structure is similar to the (3√3 × 3√3)R30°) adsorption structure that is formed on Ir(111) upon exposure to 1 mbar of CO. Further, density functional theory calculations reveal that the structural and electronic properties of CO-intercalated graphene are similar to p-doped freestanding graphene. Finally we...

  12. Ab initio Calculations of the Formation Energies of Lithium Intercalations in SnSb

    Institute of Scientific and Technical Information of China (English)

    Zhufeng HOU; Aiyu LI; Zizhong ZHU; Meichun HUANG; Yong YANG

    2004-01-01

    SnSb has attracted a great attention in recent investigations as an anode material for Li ion batteries. The formation energies and electronic properties of the Li intercalations in SnSb have been calculated within the framework of local density functional theory and the first-principles pseudopotential technique. The changes of volumes, band structures, charge density analysis and the electronic density of states for the Li intercalations are presented. The results show that the average Li intercalation formation energy per Li atom is around 2.7 eV.

  13. Rhodium target preparation from homemade chloride plating baths used for the industrial cyclotron production of palladium-L03

    International Nuclear Information System (INIS)

    Purpose: To avoid acquisition problems of commercially available western rhodium plating solutions in developing countries, a new plating/recovery cycle for Rh-103 electroplated target material (1 g Rh per target) used for the industrial cyclotron production of Pd-103 was developed. Rhodium chloride plating solutions can be prepared by dissolution of the analytical grade compound or from rhodium recovery solutions obtained after electrosolubilisation of irradiated targets and extraction of palladium. Methods: The technology involves the selective removal of the copper target backing of an irradiated target in concentrated nitric acid using a homemade flow-through stripper. The resulting rhodium fragments are dissolved in a constant-volume (40 ml), homemade graphite centrifugal ac-electrodissolution mini-reactor operating at 90 degree C, 2 A.cm-2 and 1000-rpm rotation speed. The system allows time-controlled 99 % solubilisation of up to 3g rhodium (as fragments, powder or small pieces of wire) in less than 3 hours when 12 N hydrochloric acid is applied. Upon solvent-solvent extraction of the non-carrier added Pd-103 from the resulting HCI solution; the following procedure can be used for the simultaneous preparation of 4 targets showing a surface area of 11.69 cm2 and a physical thickness of 48 Um. Dissolve an amount of hydrated RhC13 containing 2.8 g of rhodium in 400 ml of water. Alternatively, the filtered (0.45 μm filter) combined recovery solutions containing the same weight of rhodium can be evaporated to near dryness (350 degree C at the start, 150 degree C near the end) and residue taken up (gentle stirring, 50 degree C) in 400 ml of distilled water, After filtration, a stress reducing agent (sulfamic acid) is added and the pH sodium hydroxide. Upon make up to volume (450 ml) adjusted to the optimum value (pH = 2) with and preheating to 40 degree C, the resulting solution is introduced in a cylindrical home-made constant-volume, 4- target plating vessel

  14. Bulky PAH-DNA induced by exposure of a co-culture model of human alveolar macrophages and embryonic epithelial cells to atmospheric particulate pollution

    International Nuclear Information System (INIS)

    Because of their deep penetration in human lungs, fine airborne particulate matter were described as mainly responsible for the deleterious effects of exposure to air pollution on health. Organic constituents are adsorbed on particles surface and, after inhalation, some (polycyclic aromatic hydrocarbons, PAHs) can be activated into reactive metabolites and can bind to DNA. The formation of bulky DNA adducts has been researched after exposure of mono-and co-cultures of alveolar macrophages (AM) and human embryonic human lung epithelial (L132), to fine air pollution particulate matter Air samples have been collected with cascade impactor and characterized: size distribution (92.15% 2/g), inorganic (Fe, AI, Ca, Na, K, Mg, Pb, etc.) and organic compounds (PAHs, etc.). 32P post-labeling method was applied to detect bulky DNA adducts in AM and L132, in mono-and co-cultures, 72 h after their exposure to atmospheric particles at their Lethals and Effects concentrations or (LC or CE) to 50% (i.e. MA: EC50 = 74.63 μg/mL and L132: LC-5-0 = 75.36 μg/mL). Exposure to desorbed particles (MA: C1= 61.11 μg/mL and L132 : C2 = 61.71 μg/mL) and B[a]P (1 μM) were included. Bulky PAH-DNA adducts were detected in AM in mono-culture after exposure to total particles (Pt), to B[a]P and desorbed particles (Pd). Whatever the exposure, no DNA adduct was detected in L132 in mono-culture. These results are coherent with the enzymatic activities of cytochrome P450 l Al in AM and L132. Exposure of co-culture to Pt, or Pd induced bulky adducts to DNA in AM but not in L132. Exposure to B[a]P alone has altered the DNA of AM and L132, in co-culture. Exposure to Pt is closer to the environmental conditions, but conferred an exposure to amounts of genotoxic agents compared to studies using organic extracts. The formation of bulky DNA adducts was nevertheless observed in AM exposed to Pt, in mono- or co-culture, indicating that they were competent in terms of metabolic activation of PAHs. The DNA

  15. Investigation of sorption of palladium, ruthenium and rhodium ions from nitric acid solutions sorbents of different sorts

    International Nuclear Information System (INIS)

    Data are obtained on the Pd, Ru and Rh platinum metal ion sorption from nitric acid solutions on ion-exchange resins and nonorganic sorbents of different classes. It is determined that the sorbent capacity in relation to palladium is 1-2 orders higher of corresponding capacities in relation to ruthenium and rhodium. Series of sorption ability of sorbents are determined in relation to ions of considered elements in 3 mol/l HNO3

  16. Rhodium Catalysts in the Oxidation of CO by O2 and NO: Shape, Composition, and Hot Electron Generation

    OpenAIRE

    Renzas, James Russell

    2010-01-01

    AbstractRhodium Catalysts in the Oxidation of CO by O2 and NO: Shape, Composition, and Hot Electron GenerationbyJames Russell RenzasDoctor of Philosophy in ChemistryUniversity of California, BerkeleyProfessor Gabor A. Somorjai, ChairProfessor Stephen R. LeoneProfessor Jeffrey Bokor It is well known that the activity, selectivity, and deactivation behavior of heterogeneous catalysts are strongly affected by a wide variety of parameters, including but not limited to nanoparticle size, ...

  17. Manipulating the concavity of rhodium nanocubes enclosed by high-index facets via site-selective etching.

    Science.gov (United States)

    Chen, Yumin; Chen, Qing-Song; Peng, Si-Yan; Wang, Zhi-Qiao; Lu, Gang; Guo, Guo-Cong

    2014-02-18

    Manipulating the degrees of concavity or Miller indices of high-index facets is significant for metal nanocrystals to further tailor their properties; however, generating a concave surface with negative curvature is still in the early development stage and tuning the degree of concavity remains a challenge. Herein, we have developed a simple and effective site-selective etching strategy to manipulate the concavity of rhodium (Rh) nanocrystals with high-index facets. PMID:24336637

  18. Isomerization of Olefins Triggered by Rhodium-Catalyzed C–H Bond Activation: Control of Endocyclic β-Hydrogen Elimination**

    OpenAIRE

    Yip, Stephanie Y Y; Aïssa, Christophe

    2015-01-01

    Five-membered metallacycles are typically reluctant to undergo endocyclic β-hydrogen elimination. The rhodium-catalyzed isomerization of 4-pentenals into 3-pentenals occurs through this elementary step and cleavage of two C–H bonds, as supported by deuterium-labeling studies. The reaction proceeds without decarbonylation, leads to trans olefins exclusively, and tolerates other olefins normally prone to isomerization. Endocyclic β-hydrogen elimination can also be controlled in an enantiodiverg...

  19. Square-planar Diphosphinoazine Rhodium(I) Amido Carbonyl Complexes with an Unsymmetrical PNP’ Pincer-type Coordination

    Czech Academy of Sciences Publication Activity Database

    Pošta, Martin; Čermák, Jan; Sýkora, Jan; Vojtíšek, P.; Císařová, I.

    2008-01-01

    Roč. 693, č. 11 (2008), s. 1997-2003. ISSN 0022-328X R&D Projects: GA ČR GA203/01/0554; GA ČR GA203/06/0738; GA MŠk(CZ) LC06070 Institutional research plan: CEZ:AV0Z40720504 Keywords : diphosphinoazines * rhodium carbonyl complexes * pincer complexes Subject RIV: CC - Organic Chemistry Impact factor: 1.866, year: 2008

  20. Rhodium-Catalyzed Acyloxy Migration of Propargylic Esters in Cycloadditions, Inspiration from Recent “Gold Rush”

    OpenAIRE

    Shu, Xing-Zhong; Shu, Dongxu; Schienebeck, Casi M.; TANG, WEIPING

    2012-01-01

    Transition metal-catalyzed acyloxy migration of propargylic esters offers versatile entries to allene and vinyl carbene intermediates for various fascinating subsequent transformations. Most π-acidic metals (e.g. gold and platinum) are capable of facilitating these acyloxy migration events. However, very few of these processes involve redox chemistry, which are well-known for most other transition metals such as rhodium. The coupling of acyloxy migration of propargylic esters with oxidative a...

  1. Uncertainty estimation of measurement result about working platinum-rhodium10 and platinum thermocouple of level II

    International Nuclear Information System (INIS)

    This paper analyzes and evaluates the uncertainty of measurement result of working Platinum-Rhodium10 and Platinum thermocouple level II by double pole method. It presents the thermo-voltage expanded uncertainty and corresponding temperature span of measurement result when confidence level p = 0.95. The estimation result shows that the temperature corresponding to the expanded uncertainty of the thermocouple is between 0.6 degree C and 1.9 degree C. (author)

  2. Asymmetric Conjugate Alkynylation of Cyclic α,β-Unsaturated Carbonyl Compounds with a Chiral Diene Rhodium Catalyst.

    Science.gov (United States)

    Dou, Xiaowei; Huang, Yinhua; Hayashi, Tamio

    2016-01-18

    Asymmetric conjugate alkynylation of cyclic α,β-unsaturated carbonyl compounds (ketones, esters, and amides) was realized by use of diphenyl[(triisopropylsilyl)ethynyl]methanol as an alkynylating reagent in the presence of a rhodium catalyst coordinated with a new chiral diene ligand (Fc-bod; bod=bicyclo[2.2.2]octa-2,5-diene, Fc=ferrocenyl) to give high yields of the corresponding β-alkynyl-substituted carbonyl compounds with 95-98% ee. PMID:26636764

  3. Applying Adjacent Hyperbolas to Calculation of the Upper Limit of the Periodic Table of Elements, with Use of Rhodium

    Directory of Open Access Journals (Sweden)

    Khazan A.

    2011-01-01

    Full Text Available In the earlier study (Khazan A. Upper Limit in Mendeleev’s Periodic Table — Ele- ment No. 155. 2nd ed., Svenska fysikarkivet, Stockholm, 2010 the author showed how Rhodium can be applied to the hyperbolic law of the Periodic Table of Elements in or- der to calculate, with high precision, all other elements conceivable in the Table. Here we obtain the same result, with use of fraction linear functions (adjacent hyperbolas.

  4. Applying Adjacent Hyperbolas to Calculation of the Upper Limit of the Periodic Table of Elements, with Use of Rhodium

    OpenAIRE

    Khazan A.

    2011-01-01

    In the earlier study (Khazan A. Upper Limit in Mendeleev’s Periodic Table — Ele- ment No. 155. 2nd ed., Svenska fysikarkivet, Stockholm, 2010) the author showed how Rhodium can be applied to the hyperbolic law of the Periodic Table of Elements in or- der to calculate, with high precision, all other elements conceivable in the Table. Here we obtain the same result, with use of fraction linear functions (adjacent hyperbolas).

  5. Applying Adjacent Hyperbolas to Calculation of the Upper Limit of the Periodic Table of Elements, with Use of Rhodium

    Directory of Open Access Journals (Sweden)

    Khazan A.

    2011-01-01

    Full Text Available In the earlier study (Khazan A. Upper Limit in Mendeleev's Periodic Table - Element No.155. 2nd ed., Svenska fysikarkivet, Stockholm, 2010 the author showed how Rhodium can be applied to the hyperbolic law of the Periodic Table of Elements in order to calculate, with high precision, all other elements conceivable in the Table. Here we obtain the same result, with use of fraction linear functions (adjacent hyperbolas.

  6. Instability of the rhodium magnetic moment as origin of the metamagnetic phase transition in alpha-FeRh

    OpenAIRE

    Gruner, M. E.; Hoffmann, E.; Entel, P.

    2002-01-01

    Based on ab initio total energy calculations we show that two magnetic states of rhodium atoms together with competing ferromagnetic and antiferromagnetic exchange interactions are responsible for a temperature induced metamagnetic phase transition, which experimentally is observed for stoichiometric alpha-FeRh. A first-principle spin-based model allows to reproduce this first-order metamagnetic transition by means of Monte Carlo simulations. Further inclusion of spacial variation of exchange...

  7. Rhodium(i)-catalysed skeletal reorganisation of benzofused spiro[3.3]heptanes via consecutive carbon-carbon bond cleavage.

    Science.gov (United States)

    Matsuda, Takanori; Yuihara, Itaru; Kondo, Kazuki

    2016-08-01

    Skeletal reorganisation of benzofused spiro[3.3]heptanes has been achieved using rhodium(i) catalysts. The reaction of benzofused 2-(2-pyridylmethylene)spiro[3.3]heptanes proceeds via sequential C-C bond oxidative addition and β-carbon elimination. On the other hand, benzofused spiro[3.3]heptan-2-ols undergo two consecutive β-carbon elimination processes. In both cases, substituted naphthalenes are obtained. PMID:27357097

  8. Dispersive oxidation of rhodium clusters in Na-Y by the combined action of zeolite protons and carbon monoxide

    International Nuclear Information System (INIS)

    This paper uses x-ray photoelectron spectroscopy, fourier transform infrared spectroscopy and temperature programmed mass-spectrometric analysis to study the interaction of Na-Y supported rhodium with hydrogen, carbon monoxide, and zeolite protons. This report attempts to clarify the mechanism of dispersive oxidation of reduced Rh particles in the presence of CO, leading to the formation of Rh+(CO)2 cations

  9. Intercalation of push-pull molecules into layered materials bearing acidic functionalities

    Czech Academy of Sciences Publication Activity Database

    Zima, Vítězslav; Melánová, Klára; Svoboda, Jan; Beneš, L.; Knotek, P.

    Mulhouse: Univ. Hazte Alsace, 2014. [International Workshop on Layered Materials /5./. 27.08.2014-29.08.2014, Mulhouse] Institutional support: RVO:61389013 Keywords : zirconium phosphate * phosphate * intercalation Subject RIV: CA - Inorganic Chemistry

  10. Improved properties of acryl-urethane networks by addition of montmorillonite intercalates

    Czech Academy of Sciences Publication Activity Database

    Zelenka, J.; Vlček, T.; Zetková, K.; Vlasák, P.; Dušek, Karel; Dušková, Miroslava; Dobáš, I.

    Larnaca : University of Cyprus, 2008. s. 108. [Polymer Networks Group Meeting /19./. 22.06.2008-26.06.2008, Larnaca] Institutional research plan: CEZ:AV0Z40500505 Keywords : improved properties * montmorillonite intercalates * compatibility Subject RIV: CD - Macromolecular Chemistry

  11. Optimization of the Thermoelectric Figure of Merit in Crystalline C60 with Intercalation Chemistry.

    Science.gov (United States)

    Kim, Jeong Yun; Grossman, Jeffrey C

    2016-07-13

    Crystalline C60 is an appealing candidate material for thermoelectric (TE) applications due to its extremely low thermal conductivity and potentially high electrical conductivity with metal atom intercalation. We investigate the TE properties of crystalline C60 intercalated with alkali and alkaline earth metals using both classical and quantum mechanical calculations. For the electronic structure, our results show that variation of intercalated metal atoms has a large impact on energy dispersions, which leads to broad tunability of the power factor. For the thermal transport, we show that dopants introduce strong phonon scattering into crystalline C60, leading to considerably lower thermal conductivity. Taking both into account, our calculations suggest that appropriate choice of metal atom intercalation in crystalline C60 could yield figures of merit near 1 at room temperature. PMID:27322341

  12. Novel alkylimidazolium/vanadium pentoxide intercalation compounds with excellent adsorption performance for methylene blue

    Science.gov (United States)

    Kong, AiGuo; Ding, Yong Jie; Wang, Ping; Zhang, Heng Qiang; Yang, Fan; Shan, Yong Kui

    2011-02-01

    Novel alkylimidazolium-intercalated V 2O 5 compounds were synthesized by a redox reaction between iodide ion and V 2O 5. The X-ray photoelectron spectroscopy and the diffuse reflectance UV-vis spectrometry experiments reveal that the vanadium in the intercalated V 2O 5 products was partially reduced by an iodide ion and the resultant iodine can be removed in the final products. The transmission electron microscope observation and X-ray diffraction analysis testify that the prepared alkylimidazolium/V 2O 5 intercalation compounds have typical lamellar structure with different d100 interlayer spacing values and the special straw-like nanofiber morphology with the length of 0.5-10 μm. Systematic investigation indicates that new intercalation compounds possess the extraordinary adsorption performance for methylene blue in an aqueous solution.

  13. Na and Cs intercalation of 2H-TaSe2 studied by photoemission

    International Nuclear Information System (INIS)

    The electronic structure of the layered compound 2H-TaSe2 has been studied using angle-resolved photoemission before and after in situ intercalation with Na and Cs. Core level spectra verified that Na and Cs both intercalate easily at room temperature, with only small amounts remaining on the surface. Valence band spectra revealed changes in the electronic band structure which were much more extensive than predicted by the rigid band model, but which were in reasonable agreement with theoretical bands calculated by the LAPW method. Some discrepancies between the experimental and calculated results are probably due to intercalation induced changes in the stacking of host layers. A general similarity with results from transition metal dichalcogenides with 1T structure indicates that the intercalation properties are not critically dependent on the internal structure of the host layers. (author)

  14. Periodic arrays of intercalated atoms in twisted bilayer graphene: An ab initio investigation

    Science.gov (United States)

    Miwa, R. H.; Venezuela, P.; Morell, Eric Suárez

    2015-09-01

    We have performed an ab initio investigation of transition metals (TMs =Mo ,Ru ,Co ,andPt ) embedded in twisted bilayer graphene (tBG) layers. Our total energy results reveal that, triggered by the misalignment between the graphene layers, Mo and Ru atoms may form a quasiperiodic (triangular) array of intercalated atoms. In contrast, the formation of those structures is not expected for the other TMs, the Co and Pt atoms. The net magnetic moment (m ) of Mo and Ru atoms may be quenched upon intercalation, depending on the stacking region (AA or AB). For instance, we find a magnetic moment of 0.3 μB(1.8 μB) for Ru atoms intercalated between the AA (AB) regions of the stacked twisted layers. Through simulated scanning tunneling microscopy (STM) images, we verify that the presence of intercalated TMs can be identified by the formation of bright (hexagonal) spots lying on the graphene surface.

  15. Synthesis, Structural Characterization of TTM-TTF Intercalated with Lamellar MnPS3

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xuan; CHEN Xing-Guo; FU Yang; SU Xu; QIN Jin-Gui

    2003-01-01

    @@ Intercalation of organic species into layer inorganic solids provides a useful approach to creating ordered organ ic-inorganic nanocomposite materials with novel properties compared with the parent compounds, and hence has attracted much attention in recent years. [1] Clement and co-workers had reported that an organic electron donor TTF monocation intercalated into the MPS3 (M = Mn, Fe), and the intercalates exhibited much higher conductivity than the corresponding pure host compounds. Our group also synthesized the intercalation compound of BEDT-TTF into MnPS3, which exhibits the room temperature conductivity of 8.5 × 10-5 S/cm, 1O5 times higher than that of the pristine MnPS3 ( < 10- 10 S/cm). [2

  16. DNA binding and topoisomerase II inhibitory activity of water-soluble ruthenium(II) and rhodium(III) complexes.

    Science.gov (United States)

    Singh, Sanjay Kumar; Joshi, Shweta; Singh, Alok Ranjan; Saxena, Jitendra Kumar; Pandey, Daya Shankar

    2007-12-10

    Water-soluble piano-stool arene ruthenium complexes based on 1-(4-cyanophenyl)imidazole (CPI) and 4-cyanopyridine (CNPy) with the formulas [(eta6-arene)RuCl2(L)] (L = CPI, eta6-arene = benzene (1), p-cymene (2), hexamethylbenzene (3); L = CNPy, eta6-arene = benzene (4), p-cymene (5), hexamethylbenzene (6)) have been prepared by our earlier methods. The molecular structure of [(eta6-C6Me6)RuCl2(CNPy)] (6) has been determined crystallographically. Analogous rhodium(III) complex [(eta5-C5Me5)RhCl2(CPI)] (7) has also been prepared and characterized. DNA interaction with the arene ruthenium complexes and the rhodium complex has been examined by spectroscopic and gel mobility shift assay; condensation of DNA and B-->Z transition have also been described. Arene ruthenium(II) and EPh3 (E = P, As)-containing arene ruthenium(II) complexes exhibited strong binding behavior, however, rhodium(III) complexes were found to be Topo II inhibitors with an inhibition percentage of 70% (7) and 30% (7a). Furthermore, arene ruthenium complexes containing polypyridyl ligands also act as mild Topo II inhibitors (10%, 3c and 40%, 3d) in contrast to their precursor complexes. Complexes 4-6 also show significant inhibition of beta-hematin/hemozoin formation activity. PMID:18001110

  17. Catalytic wet oxidation of ammonia solution: Activity of the nanoscale platinum-palladium-rhodium composite oxide catalyst

    International Nuclear Information System (INIS)

    Aqueous solutions of 400-1000 mg/L of ammonia were oxidized in a trickle-bed reactor (TBR) in this study of nanoscale platinum-palladium-rhodium composite oxide catalysts, which were prepared by the co-precipitation of H2PtCl6, Pd(NO3)3 and Rh(NO3)3. Hardly any of the dissolved ammonia was removed by wet oxidation in the absence of any catalyst, whereas about 99% of the ammonia was reduced during wet oxidation over nanoscale platinum-palladium-rhodium composite oxide catalysts at 503 K in an oxygen partial pressure of 2.0 MPa. A synergistic effect exists in the nanoscale platinum-palladium-rhodium composite structure, which is the material with the highest ammonia reduction activity. The nanometer-sized particles were characterized by TEM, XRD and FTIR. The effect of the initial concentration and reaction temperature on the removal of ammonia from the effluent streams was also studied at a liquid hourly space velocity of under 9 h-1 in the wet catalytic processes

  18. In Situ Structure-Function Studies of Oxide Supported Rhodium Catalysts by Combined Energy Dispersive XAFS and DRIFTS Spectroscopies

    International Nuclear Information System (INIS)

    The techniques of energy dispersive EXAFS (EDE), diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) and mass spectrometry (MS) have been combined to study the structure and function of an oxide supported metal catalyst, namely 5 wt% Rh/Al2O3. Using a FreLoN camera as the EDE detector and a rapid-scanning IR spectrometer, experiments could be performed with a repetition rate of 50 ms. The results show that the nature of the rhodium centers is a function of the partial pressures of the reacting gases (CO and NO) and also temperature. This combination of gases oxidizes metallic rhodium particles to Rh(CO)2 at room temperature. The proportion of the rhodium adopting this site increases as the temperature is raised (up to 450 K). Above that temperature the dicarbonyl decomposes and the metal reclusters. Once this condition is met, catalysis ensues. Gas switching techniques show that at 573 K with NO in excess, the clusters can be oxidized rapidly to afford a linear nitrosyl complex; re-exposure to CO also promotes reclustering and the CO adopts terminal (atop) and bridging (2-fold) sites

  19. An insight on the weakening of the interlayer bonds in a Cameroonian kaolinite through DMSO intercalation

    OpenAIRE

    Mbey, Jean-Aimé; Thomas, Fabien; NGALLY-SABOUANG, Cyrill-Joel; LIBOUM, François; Njopwouo, Daniel

    2013-01-01

    In this study, intercalation of dimethylsulphoxide (DMSO) in a Cameroonian kaolinite is used to achieve weakening of the interlayer hydrogen bonds, in the perspective of dispersion or even exfoliation of the clay within polymer composite materials. Displacement of intercalated DMSO by ethyl acetate and ammonium acetate is studied in order to simulate the interactions with the polymer matrix. The exfoliation of the kaolinite is well evidenced by X-ray diffraction and SEM observations. The disr...

  20. A molecular dynamics study of lithium grain boundary intercalation in graphite

    International Nuclear Information System (INIS)

    Lithium-ion diffusion rates in graphitic battery anodes have been shown to vary greatly in experiments, with numerous hypotheses to explain this behavior. Here, we model several grain boundaries using molecular dynamics and quantify intercalation from the free surface. A significant variation in intercalation rates is revealed as dictated by local bond structure where the grain boundary intersects the free surface. Data presented may help explain dramatic differences in diffusion rates and permit more accurate predictions of lithium-ion battery performance

  1. Evolution of interfacial intercalation chemistry on epitaxial graphene/SiC by surface enhanced Raman spectroscopy

    International Nuclear Information System (INIS)

    Highlights: • H-intercalated epitaxial graphene–SiC interface studied with surface enhanced Raman. • Evolution of graphene and H–Si interface with UV-ozone, annealing and O-exposure. • H–Si interface and quasi-freestanding graphene are retained after UV-ozone treatment. • Enhanced ozonolytic reactivity at the edges of H-intercalated defected graphene. • Novel SERS method for characterizing near-surface graphene–substrate interfaces. - Abstract: A rapid and facile evaluation of the effects of physical and chemical processes on the interfacial layer between epitaxial graphene monolayers on SiC(0 0 0 1) surfaces is essential for applications in electronics, photonics, and optoelectronics. Here, the evolution of the atomic scale epitaxial graphene-buffer-layer–SiC interface through hydrogen intercalation, thermal annealings, UV-ozone etching and oxygen exposure is studied by means of single microparticle mediated surface enhanced Raman spectroscopy (smSERS). The evolution of the interfacial chemistry in the buffer layer is monitored through the Raman band at 2132 cm−1 corresponding to the Si-H stretch mode. Graphene quality is monitored directly by the selectively enhanced Raman signal of graphene compared to the SiC substrate signal. Through smSERS, a simultaneous correlation between optimized hydrogen intercalation in epitaxial graphene/SiC and an increase in graphene quality is uncovered. Following UV-ozone treatment, a fully hydrogen passivated interface is retained, while a moderate degradation in the quality of the hydrogen intercalated quasi-freestanding graphene is observed. While hydrogen intercalated defect free quasi-freestanding graphene is expected to be robust upon UV-ozone, thermal annealing, and oxygen exposure, ozonolytic reactivity at the edges of H-intercalated defected graphene results in enhanced amorphization of the quasi-freestanding (compared to non-intercalated) graphene, leading ultimately to its complete etching

  2. Structural, energetic and electronic properties of intercalated boron–nitride nanotubes

    Indian Academy of Sciences (India)

    S Rada; M Rada; E Culea

    2013-04-01

    The effects of chirality and the intercalation of transitional metal atoms inside single walled BN nanotubes on structural, energetic and electronic properties have been considered in this paper. The thermodynamic stability of BN nanotubes can be improved by the intercalation of cobalt or nickel. BN nanotubes can behave like an ideal non-interacting hosts for these one-dimensional chains of metal atoms. Their electronic properties are insignificantly modified.

  3. Optimal design of parallel triplex forming oligonucleotides containing Twisted Intercalating Nucleic Acids—TINA

    OpenAIRE

    Schneider, Uffe V.; Mikkelsen, Nikolaj D.; Jøhnk, Nina; Okkels, Limei M.; Westh, Henrik; Lisby, Gorm

    2010-01-01

    Twisted intercalating nucleic acid (TINA) is a novel intercalator and stabilizer of Hoogsteen type parallel triplex formations (PT). Specific design rules for position of TINA in triplex forming oligonucleotides (TFOs) have not previously been presented. We describe a complete collection of easy and robust design rules based upon more than 2500 melting points (T m) determined by FRET. To increase the sensitivity of PT, multiple TINAs should be placed with at least 3 nt in-between or preferabl...

  4. Recent Developments in the Chemistry of Deoxyribonucleic Acid (DNA Intercalators: Principles, Design, Synthesis, Applications and Trends

    Directory of Open Access Journals (Sweden)

    Alexandre A. M. Lapis

    2009-05-01

    Full Text Available In the present overview, we describe the bases of intercalation of small molecules (cationic and polar neutral compounds in DNA. We briefly describe the importance of DNA structure and principles of intercalation. Selected syntheses, possibilities and applications are shown to exemplify the importance, drawbacks and challenges in this pertinent, new, and exciting research area. Additionally, some clinical applications (molecular processes, cancer therapy and others and trends are described.

  5. Intercalation of urea into kaolinite for preparation of controlled release fertilizer

    OpenAIRE

    Mahdavi Fariba; Abdul Rashid Suraya; Khanif Yusop Mohd

    2014-01-01

    In this study urea was intercalated between layers of kaolinite by dry grinding technique to be used for preparing controlled release fertilizer. X-ray powder diffraction (XRPD) patterns confirmed the intercalation of urea into kaolinite by the significant expansion of the basal spacing of kaolinite layers from 0.710 nm to 1.090 nm. Fourier transform infrared spectroscopy (FT-IR) also confirmed the hydrogen bonding between urea and kaolinite. Based on CHNS ...

  6. Intercalation and De-intercalation of a Dual Phenoxy herbicides into Zn-Al-Layered Double Hydroxide Effect of Anionic Size

    International Nuclear Information System (INIS)

    Agrochemicals, in particular herbicides such as 4-(2,4- dichlorophenoxy)butyrate (DPBA) and 2-(3- chlorophenoxy)propionate (CPPA) have been intercalated simultaneously into Zn/ Al-LDH by direct co-precipitation method to form a new nano hybrid material labeled as NCDD. XRD and UV-Visible spectroscopy results show that the intercalation and release of the dual herbicides are influenced by the anion size. These results will be useful as the starting point to develop tunable controlled release property. (author)

  7. Sugar-anionic clay composite materials: intercalation of pentoses in layered double hydroxide

    Science.gov (United States)

    Aisawa, Sumio; Hirahara, Hidetoshi; Ishiyama, Kayoko; Ogasawara, Wataru; Umetsu, Yoshio; Narita, Eiichi

    2003-09-01

    The intercalation of non-ionized guest pentoses (ribose and 2-deoxyribose) into the Mg-Al and Zn-Al layered double hydroxides (LDHs) was carried out at 298 K by the calcination-rehydration reaction using the Mg-Al and Zn-Al oxide precursors calcined at 773 K. The resulting solid products reconstructed the LDH structure with incorporating pentoses, and the maximum amount of ribose intercalated by the Mg-Al oxide precursor was approximately 20 times that by the Zn-Al oxide precursor. The ribose/Mg-Al LDH was observed to have the expanded LDH structure with a broad (003) spacing of 0.85 nm. As the thickness of the LDH hydroxide basal layer is 0.48 nm, the interlayer distance of the ribose/Mg-Al LDH is 0.37 nm. This value corresponds to molecular size of ribose in thickness (0.36 nm), supporting that ribose is horizontally oriented in the interlayer space of LDH. The maximum amount of ribose intercalated by the Mg-Al oxide precursor was approximately 5 times that of 2-deoxyribose. Ribose is substituted only by the hydroxyl group at C-2 position for 2-deoxyribose. Therefore, the number of hydroxyl group of sugar is essentially important for the intercalation of sugar molecule into the LDH, suggesting that the intercalation behavior of sugar for the LDH was greatly influenced by hydrogen bond between hydroxyl group of the intercalated pentose and the LDH hydroxide basal layers.

  8. Study on intercalation of ionic liquid into montmorillonite and its property evaluation

    International Nuclear Information System (INIS)

    Present study report fabrication of a solid–liquid intercalated compound using montmorillonite and ionic liquid [IL; 1-Butyl-3-methylimidazolium tetrafluoroborate; ([BMIM][BF4])]. The intercalation of IL into the interlayer of montmorillonite was revealed by swelling behavior measured by X-ray diffraction (XRD) and cation exchange capacity (CEC). The crystal swelling structure of intercalation compound was further evidenced by transmission electron microscope (TEM). From these results, the arrangement of [BMIM]+ ions (cationic part of IL) into the unit layer were proposed. Furthermore, the montmorillonite showed electrical conductivity with the aid of IL. This demonstrates a successful attempt to fabricate a solid–liquid state nano-structure compound as possible transparent electrically conducting thin film. -- Highlights: ► Direct intercalation of ionic liquid into the montmorillonite was studied. ► The crystal swelling structure in liquid state was successfully characterized by TEM. ► We proposed the atomic arrangement of intercalated compound using ionic liquid. ► Ionic liquid is useful for fabricating an intercalated compound with electrical-conductivity.

  9. In situ intercalation dynamics in inorganic-organic layered perovskite thin films.

    Science.gov (United States)

    Ahmad, Shahab; Kanaujia, Pawan K; Niu, Wendy; Baumberg, Jeremy J; Vijaya Prakash, G

    2014-07-01

    The properties of layered inorganic semiconductors can be manipulated by the insertion of foreign molecular species via a process known as intercalation. In the present study, we investigate the phenomenon of organic moiety (R-NH3I) intercalation in layered metal-halide (PbI2)-based inorganic semiconductors, leading to the formation of inorganic-organic (IO) perovskites [(R-NH3)2PbI4]. During this intercalation strong resonant exciton optical transitions are created, enabling study of the dynamics of this process. Simultaneous in situ photoluminescence (PL) and transmission measurements are used to track the structural and exciton evolution. On the basis of the experimental observations, a model is proposed which explains the process of IO perovskite formation during intercalation of the organic moiety through the inorganic semiconductor layers. The interplay between precursor film thickness and organic solution concentration/solvent highlights the role of van der Waals interactions between the layers, as well as the need for maintaining stoichiometry during intercalation. Nucleation and growth occurring during intercalation matches a Johnson-Mehl-Avrami-Kolmogorov model, with results fitting both ideal and nonideal cases. PMID:24905435

  10. In Situ Intercalation Dynamics in Inorganic–Organic Layered Perovskite Thin Films

    Science.gov (United States)

    2014-01-01

    The properties of layered inorganic semiconductors can be manipulated by the insertion of foreign molecular species via a process known as intercalation. In the present study, we investigate the phenomenon of organic moiety (R-NH3I) intercalation in layered metal-halide (PbI2)-based inorganic semiconductors, leading to the formation of inorganic–organic (IO) perovskites [(R-NH3)2PbI4]. During this intercalation strong resonant exciton optical transitions are created, enabling study of the dynamics of this process. Simultaneous in situ photoluminescence (PL) and transmission measurements are used to track the structural and exciton evolution. On the basis of the experimental observations, a model is proposed which explains the process of IO perovskite formation during intercalation of the organic moiety through the inorganic semiconductor layers. The interplay between precursor film thickness and organic solution concentration/solvent highlights the role of van der Waals interactions between the layers, as well as the need for maintaining stoichiometry during intercalation. Nucleation and growth occurring during intercalation matches a Johnson–Mehl–Avrami–Kolmogorov model, with results fitting both ideal and nonideal cases. PMID:24905435

  11. Novel alkylimidazolium/vanadium pentoxide intercalation compounds with excellent adsorption performance for methylene blue

    International Nuclear Information System (INIS)

    Novel alkylimidazolium-intercalated V2O5 compounds were synthesized by a redox reaction between iodide ion and V2O5. The X-ray photoelectron spectroscopy and the diffuse reflectance UV-vis spectrometry experiments reveal that the vanadium in the intercalated V2O5 products was partially reduced by an iodide ion and the resultant iodine can be removed in the final products. The transmission electron microscope observation and X-ray diffraction analysis testify that the prepared alkylimidazolium/V2O5 intercalation compounds have typical lamellar structure with different d100 interlayer spacing values and the special straw-like nanofiber morphology with the length of 0.5-10 μm. Systematic investigation indicates that new intercalation compounds possess the extraordinary adsorption performance for methylene blue in an aqueous solution. -- Graphical abstract: The alkylimidazolium-intercalated V2O5 compounds with special straw-like nanofiber morphology were synthesized by a redox reaction between iodide ion and V2O5, which show the excellent adsorption performance for methylene blue in an aqueous medium. Display Omitted Research highlights: → Novel alkylimidazolium-intercalated V2O5 compounds. → A simple preparation method by a redox reaction between iodide ion in ionic liquid and V2O5. → The excellent adsorption performance for methylene blue in an aqueous medium.

  12. Intercalation and Distribution of Silver in the Transition Metal Dichalcogenide 1T-TITANIUM-DISULFIDE.

    Science.gov (United States)

    Kaluarachchi, Dayakanthi

    The intercalation and motion of silver (Ag) in partially intercalated titanium disulphide (TiS _{rm 2}) crystals were studied using a scanning Auger electron microscope with ion sputtering, a scanning electron microscope with an x-ray fluorescence attachment, an optical microscope and radioactive tracers. The x-ray fluorescence results indicated a rapid conversion of stage 1 Ag into stage 2 Ag at room temperature and a stationary behavior of the stage 2 Ag after the stage conversion was completed. The radioactive tracer results showed that stage 2 Ag was mobile during the stage 1 to stage 2 conversion and also when a crystal was being intercalated. The motion of stage 2 Ag in the bulk of a crystal was observed only when stage 1 was present in the crystal. Auger analysis with ion sputtering yielded the 3-dimensional distribution of Ag in a partially intercalated stage 2 crystal. Ag was observed to be intercalated across the crystal surface region while the bulk was intercalated only for a short distance, indicating that the Ag has a high rate of motion near the crystal surface. A stage 2 region with a high Ag concentration was observed to be unstable near the crystal surface.

  13. Raman response of Stage-1 graphite intercalation compounds revisited

    CERN Document Server

    Chacón-Torres, J C; Rosseinsky, M J; Pichler, T

    2012-01-01

    We present a detailed in-situ Raman analysis of KC8, CaC6, and LiC6 graphite intercalation compounds (GIC) to unravel their intrinsic finger print in the Stage-1 compound. Four main components were found between 1200 cm-1 and 1700 cm-1, and each of them were assigned to a corresponding vibrational mode. From a detailed line shape analysis of the intrinsic Fano-lines of the G and D components we precisely determine the position ({\\omega}ph), line width ({\\Gamma}ph) and asymmetry (q) from each component (i.e. D, G, defect modulated and deintercalated G-line mode). The calculated line width and position of the G-line allow us to extract the electron-phonon coupling constant of these compounds. A coupling constant {\\lambda}ph < 0.06 is obtained. This highlights that Raman active modes alone are not sufficient to explain the superconductivity within the electron- phonon coupling mechanism in CaC6 and KC8.

  14. Molybdenum, rhodium, and tungsten anode spectral models using interpolating polynomials with application to mammography.

    Science.gov (United States)

    Boone, J M; Fewell, T R; Jennings, R J

    1997-12-01

    Computer simulation is a convenient and frequently used tool in the study of x-ray mammography, for the design of novel detector systems, the evaluation of dose deposition, x-ray technique optimization, and other applications. An important component in the simulation process is the accurate computer-generation of x-ray spectra. A computer model for the generation of x-ray spectra in the mammographic energy range from 18 kV to 40 kV has been developed. The proposed model requires no assumptions concerning the physics of x-ray production in an x-ray tube, but rather makes use of x-ray spectra recently measured experimentally in the laboratories of the Center for Devices and Radiological Health. Using x-ray spectra measured for molybdenum, rhodium, and tungsten anode x-ray tubes at 13 different kV's (18, 20, 22, ..., 42 kV), a spectral model using interpolating polynomials was developed. At each energy in the spectrum, the x-ray photon fluence was fit using 2, 3, or 4 term (depending on the energy) polynomials as a function of the applied tube voltage (kV). Using the polynomial fit coefficients determined at each 0.5 keV interval in the x-ray spectrum, accurate x-ray spectra can be generated for any arbitrary kV between 18 and 40 kV. Each anode material (Mo, Rh, W) uses a different set of polynomial coefficients. The molybdenum anode spectral model using interpolating polynomials is given the acronym MASMIP, and the rhodium and tungsten spectral models are called RASMIP and TASMIP, respectively. It is shown that the mean differences in photon fluence calculated over the energy channels and over the kV range from 20 to 40 kV were -0.073% (sigma = 1.58%) for MASMIP, -0.145% (sigma = 1.263%) for RASMIP, and 0.611% (sigma = 2.07%) for TASMIP. The polynomial coefficients for all three models are given in an Appendix. A short C subroutine which uses the polynomial coefficients and generates x-ray spectra based on the proposed model is available on the World Wide Web at http

  15. Resistivity features in intercalated graphite compounds with bromine and iodine chloride in the region of structural phase transitions in the layer of intercalate

    International Nuclear Information System (INIS)

    In the paper anomalous changes of resistivity in graphite intercalated compounds with iodine chloride and bromine are investigated in the phase transition temperature interval. It is shown that these anomalies are caused by the change of carriers mobility in the phase transitional interval as well as by the origin of ''mobile ions liquids''

  16. Crystalline-state photochromism of rhodium dinuclear complexes having a dithionite group and its reaction dynamics

    International Nuclear Information System (INIS)

    The compounds that undergo photochromic reaction in the crystalline-state are rare and their reaction dynamics are not well characterized as a result of the low degree of interconversion ratios and/or instability of the photo-generated isomers in the solid phase. We have recently found that a rhodium dinuclear complex [(RhCp*)2(μ-CH2)2(μ-O2SSO2)] (Cp*=η5-C5Me5) having a photo-responsive dithionite group (μ-O2SSO2) undergoes an essentially 100% reversible crystalline-state photochromism upon interconversion to [(RhCp*)2(μ-CH2)2(μ-O2SOSO)]. Taking an advantage of this unique full reversibility, we have investigated the dynamics of the system by using stepwise single crystal diffraction and variable-temperature solid-state NMR technique. The stereospecific oxygen-atom rearrangement process of the dithionite ligand and reorientational motion of the Cp* ligands, which are coupled to the photochromism, are presented. (author)

  17. Complexation of diphenyl(phenylacetenyl)phosphine to rhodium(III) tetraphenyl porphyrins

    DEFF Research Database (Denmark)

    Stulz, Eugen; Scott, Sonya M; Bond, Andrew D;

    2003-01-01

    The coordination of diphenyl(phenylacetenyl)phosphine (DPAP, 1) to (X)Rh(III)TPP (X = I (2) or Me (3); TPP = tetraphenyl porphyrin) was studied in solution and in the solid state. The iodide is readily displaced by the phosphine, leading to the bis-phosphine complex [(DPAP)(2)Rh(TPP)](I) (4). The...... methylide on rhodium in 3 is not displaced, leading selectively to the mono-phosphine complex (DPAP)(Me)Rh(TPP) (5). The first and second association constants, as determined by isothermal titration calorimetry and UV-vis titrations, are in the range 10(4)-10(7) M(-1) (in CH(2)Cl(2)). Using LDI-TOF mass...... spectrometry, the mono-phosphine complexes can be detected but not the bis-phosphine complexes. The electronic spectrum of 4 is similar to those previously reported with other tertiary phosphine ligands, whereas (DPAP)(I)Rh(TPP) (6) displays a low energy B-band absorption and a high energy Q-band absorption...

  18. Nanofiltration of rhodium tris(triphenylphosphine) catalyst in ethyl acetate solution

    Science.gov (United States)

    Shaharun, Maizatul S.; Mustafa, Ahmad K.; Taha, Mohd F.

    2012-09-01

    Solvent resistant nanofiltration (SRNF) using polymer membranes has recently received enhanced attention due to the search for cleaner and more energy-efficient technologies. The large size of the rhodium tris(triphenylphosphine) [HRh(CO)(PPh3)3] catalyst (>400 Da) - relative to other components of the hydroformylation reaction provides the opportunity for a membrane separation based on retention of the catalyst species while permeating the solvent. The compatibility of the solvent-polyimide membrane (DuraMem{trade mark, serif} 200 and DuraMem{trade mark, serif} 500) combinations was assessed in terms of the membrane stability in solvent plus non-zero solvent flux at 2.0 MPa. Good HRh(CO)(PPh3)3 rejection (>0.95) and solvent fluxes of 9.9 L/m2ṡh1 at 2.0 MPa were obtained in the catalyst-ethyl acetate-DuraMem 500 system. The effect of pressure and catalyst concentration on the solvent flux and catalyst rejection was conducted on the catalyst-ethyl acetate-membrane systems. Increasing pressure substantially improved both solvent flux and catalyst rejection, while increasing catalyst concentration was found to be beneficial in terms of substantial increases in catalyst rejection without significantly affecting solvent flux.

  19. Iridium, platinum and rhodium baseline concentration in lichens from Tierra del Fuego (South Patagonia, Argentina).

    Science.gov (United States)

    Pino, Anna; Alimonti, Alessandro; Conti, Marcelo Enrique; Bocca, Beatrice

    2010-10-01

    Lichen samples of Usnea barbata were used as possible biomonitors of the atmospheric background level of iridium (Ir), platinum (Pt) and rhodium (Rh) in the remote region of Tierra del Fuego (South Patagonia, Argentina). Lichens were collected in 2006 at 53 sites covering 7 different areas of the region (24 transplanted lichens of the northern region and 29 native lichen samples of the central-southern region). A microwave acidic digestion procedure was used to mineralize the samples and a sector field inductively coupled plasma mass spectrometry method was developed to quantify the elements. The study of the influence of interferences on analyte signals and a quality control procedure were carried out. The analytical protocol was further applied to evaluate Ir, Pt and Rh bioaccumulation in lichens. The detection limits obtained were 0.010 ng g⁻¹, 0.013 ng g⁻¹ and 0.030 ng g⁻¹ for Ir, Pt and Rh, respectively. Recoveries at different fortification levels were between 96.3% and 106% and precision was 3.3% on average. The metals concentration (as dry weight) spanned the following ranges: Ir, Tierra del Fuego. Values detected are more likely influenced by the long-range atmospheric transport of these pollutants and, in comparison with densely populated areas in the world, they can represent the baseline for low impacted areas. PMID:20830409

  20. Platinum, Palladium and Rhodium levels in road dusts of Kuala Lumpur and Genting Sempah tunnel, Pahang

    International Nuclear Information System (INIS)

    An increasing demand of platinum group elements (PGE) especially platinum, palladium and rhodium in various industries has increased its concentration in the environment. Determination of PGE was measured in selected open and close sites using inductively coupled plasma-optical emission spectrometry (ICP-OES) and inductively coupled plasma-mass spectrometry (ICP-MS). Results showed that Pt concentration in road dusts of open sampling area are in the range of not detected (ND) to 200.0 ng/ g, while the concentration of Rh is in the range of 8.02 ng/ g to 97.32 ng/ g. Pt and Rh in close sampling area, Genting Sempah Tunnel are in the range of not detected (ND) to 105.7±61.1 ng/g and 8.4±1.3 ng/ g to 59.0±5.5 ng/ g respectively. The ratio of Pt to Rh in road dusts samples ranges from 1.2: 1 to 7: 1, while the ratio in catalytic converter samples is 7: 1. There is no Pd detected in any of the samples taken. The correlation between Pt, Rh and traffic-related elements with the traffic density of the sampling sites were discussed. (author)

  1. Versatile deprotonated NHC: C,N-bridged dinuclear iridium and rhodium complexes

    Science.gov (United States)

    2016-01-01

    Summary Bearing the versatility of N-heterocyclic carbene (NHC) ligands, here density functional theory (DFT) calculations unravel the capacity of coordination of a deprotonated NHC ligand (pNHC) to generate a doubly C2,N3-bridged dinuclear complex. Here, in particular the discussion is based on the combination of the deprotonated 1-arylimidazol (aryl = mesityl (Mes)) with [M(cod)(μ-Cl)] (M = Ir, Rh) generated two geometrical isomers of complex [M(cod){µ-C3H2N2(Mes)-κC2,κN3}]2). The latter two isomers display conformations head-to-head (H-H) and head-to-tail (H-T) of C S and C 2 symmetry, respectively. The isomerization from the H-H to the H-T conformation is feasible, whereas next substitutions of the cod ligand by CO first, and PMe3 later confirm the H-T coordination as the thermodynamically preferred. It is envisaged the exchange of the metal, from iridium to rhodium, confirming here the innocence of the nature of the metal for such arrangements of the bridging ligands. PMID:26877814

  2. Separation of Hydridocarbonyltris(triphenylphosphine) Rhodium (I) Catalyst Using Solvent Resistant Nano filtration Membrane

    International Nuclear Information System (INIS)

    An investigation was conducted into the nano filtration of rhodium tris(triphenyl-phosphine) [HRh(CO)(PPh3)3] catalyst used in the hydroformylation of olefins. The large size of the catalyst (>400 Da) - relative to other components of the reaction provides the opportunity for a membrane separation based on retention of the catalyst species while permeating the solvent. The compatibility of the solvent-polyimide membrane (STARMEMTM 122 and STARMEMTM 240) combinations was assessed in terms of the membrane stability in solvent plus non-zero solvent flux at 2.0 MPa. The morphology of the membrane was studied by field emission scanning electron microscopy (FESEM). The solvent flux and membrane rejection of HRh(CO)(PPh3)3 was then determined for the catalyst-solvent-membrane combination in a dead-end pressure cell. Good HRh(CO)(PPh3)3 rejection (>0.93) coupled with good solvent fluxes (>72 L/ m2 h1 at 2.0 MPa) were obtained in one of the systems tested. The effect of pressure and catalyst concentration on the solvent flux and catalyst rejection was conducted. Increasing pressure substantially improved both solvent flux and catalyst rejection, while increasing catalyst concentration was found to be beneficial in terms of substantial increases in catalyst rejection without significantly affecting the solvent flux. (author)

  3. Manifestation of external size reduction effects on the yield point of nanocrystalline rhodium using nanopillars approach

    International Nuclear Information System (INIS)

    In this study, pure rhodium was fabricated and mechanically investigated at the nanoscale for the first time. The nanopillars approach was employed to study the effects of size on the yield point. Nanopillars with different diameters were fabricated using electroplating followed by uniaxial compression tests. Scanning electron microscopy (SEM) was used as a quality control technique by imaging the pillars before and after compression to ensure the absence of cracks, buckling, barrelling or any other problems. Transmission electron microscopy and SEM were used as microstructural characterization techniques. Due to substrate-induced effects, only the plastic region of the stress–strain curves were investigated, and it was revealed that the yield point increases with size reduction up to certain limit, then decreases with further reduction of the nanopillar size (diameter). The later weakening effect is consistent with the literature, which demonstrates the reversed size effect (the failure of the plasticity theory) in nanocrystalline metals, i.e. smaller is weaker. In this study, however, the effect of size reduction is not only weakening, but is strengthening-then-weakening, which the authors believe is the true behavior of nanocrystalline materials.

  4. Combination of supported bimetallic rhodium-molybdenum catalyst and cerium oxide for hydrogenation of amide

    Science.gov (United States)

    Nakagawa, Yoshinao; Tamura, Riku; Tamura, Masazumi; Tomishige, Keiichi

    2015-02-01

    Hydrogenation of cyclohexanecarboxamide to aminomethylcyclohexane was conducted with silica-supported bimetallic catalysts composed of noble metal and group 6-7 elements. The combination of rhodium and molybdenum with molar ratio of 1:1 showed the highest activity. The effect of addition of various metal oxides was investigated on the catalysis of Rh-MoOx/SiO2, and the addition of CeO2 much increased the activity and selectivity. Higher hydrogen pressure and higher reaction temperature in the tested range of 2-8 MPa and 393-433 K, respectively, were favorable in view of both activity and selectivity. The highest yield of aminomethylcyclohexane obtained over Rh-MoOx/SiO2 + CeO2 was 63%. The effect of CeO2 addition was highest when CeO2 was not calcined, and CeO2 calcined at >773 K showed a smaller effect. The use of CeO2 as a support rather decreased the activity in comparison with Rh-MoOx/SiO2. The weakly-basic nature of CeO2 additive can affect the surface structure of Rh-MoOx/SiO2, i.e. reducing the ratio of Mo-OH/Mo-O- sites.

  5. Liquid-phase hydrogenation of aniline in the presence of deposited ruthenium and rhodium catalysts

    International Nuclear Information System (INIS)

    Effect of different parameters on the yield of the main product-cyclohexylamine, kinetics and mechanism of aniline hydrogenation in the presence of deposited ruthenium and rhodium catalysts under hydrogen pressure has been studied. Catalysts of the following composition: 1%Ru/MgO, 1%Ru/Al2O3, 5%Ru/Al2O3, 1%Rh/MgO, 5%Rh/MgO, 5%Rh/Al2O3 and 5%Rh/SiO2, prepared by the adsorption method, are investigated. The yield of the main product of aniline hydrogeration-cyclohexylamine - and composition of the mixture of final products depend on the nature of metal-catalyst, acid-base properties of the carrier. The maximum yield of primary amine (approximately 83%) is achieved in the presence of the catalysts 5%Ru/Al2O3 and 5%Rh/Si2O. The reaction order in terms of substrate is close to zero in the studied range of hydrogen pressures, in terms of hydrogen-fractional or clode to the first one with transition to the zero one in the range of high (hydrogen) pressures. Surfaces of the contacts investigated are pickled by aniline transformation products in hydrogen presence. Total seeming activation energies constitute 50+-10 kJ/mol

  6. Isotopic exchange between 2,2-dimethylbutane and deuterium on rhodium/silica gel catalysts

    International Nuclear Information System (INIS)

    Isotropic exchange between 2.2-dimethylbutane and deuterium has been investigated at 75 C on 10 rhodium on wide-pore silica gel catalysts with H(chemisorbed)/Rh(Dh) ranging from 11 to 108% and subjected to a variety of pretreatment conditions. Some catalysts were prepared by ion exchange with Rh(NH3)5(H2O)3- and some by impregnation to incipient wetness with Rh4(CO)12 or Rh6(CO)16. The turnover frequency (Nt) is affected both by Dh and by the conditions of pretreatment. The extreme variation was a factor of 330. Exchange into the ethyl group was about 10 times faster than into the t-butyl group. In general, the catalysts of largest Dh gave the largest Nt and the smallest degree of multiple exchange in the ethyl group. The pretreatment, H2, 450 C gave the largest Nt. Mere removal of H* from catalysts so treated by He, 300 C had little effect, but He, 450 C led to a substantial decrease in Nt except for 11-Rh/SiO2. The various coupled values of Nt and selectivity resulting from variations in Dh and pretreatment require a minimum of eight different sites. Nt's and selectivities in the hydrogenolysis of methylcyclopropane on these same catalysts parallel those in the exchange of neohexane

  7. Catalysis by Oxide-Supported Clusters of Iridium and Rhodium: Hydrogenation of Ethene, Propene, and Toluene

    International Nuclear Information System (INIS)

    The hydrogenation reactions of ethene, propene, and toluene were used as probes of the catalytic properties of small clusters of rhodium (Rh6) and of iridium (Ir4 and Ir6) (as well as of larger aggregates of these metals) on oxide supports (γ-Al2O3, MgO, and La2O3). The catalysts were characterized in the working state by extended X-ray absorption fine structure (EXAFS) spectroscopy, providing evidence of the cluster structures and cluster-support interactions; by infrared spectroscopy, providing evidence of hydrocarbon adsorbates and possible reaction intermediates on the clusters; and by kinetics of the hydrogenation reactions. The EXAFS data indicate that the metal clusters, while remaining intact and maintaining their bonding to the support during catalysis, underwent slight rearrangements to accommodate reactive intermediates. As the concentrations of reactive intermediates such as π-bonded alkenes and alkyls on the clusters increased, the cluster frames swelled, and the clusters flexed away from the support. The data indicate self-inhibition of reaction by adsorbed hydrocarbons and differences between ethene hydrogenation and propene hydrogenation that may arise primarily from different adsorbate-adsorbate interactions

  8. Reactions of neopentane and methylcyclobutane with hydrogen on iridium- and rhodium-carrier catalysts

    International Nuclear Information System (INIS)

    In this dissertation there were tested the reactions of neopentane and methylcyclobutane with hydrogen on thin-film-carrier catalysts Ir/Al203, Rh/Al203, Rh/TiO2 with metal particles of different size. The activity and selectivity of the catalysts at this reactions depend on the size and structure of the iridium- and rhodium particles as well as of the used carriermaterial. The attempt series were carried out with assistance of a computer-controlled microreactor to test a wide number of reactions. In order to describe the dependence of structure of this reactions as much as possible, the model-catalysts were produced under exact defined conditions and characterized in the electron microscope. Apart from the structure effects there were realized at all reactions a large influence of the partial pressure of the reactants particularly of hydrogen on the reaction kinetic. Unfortunately prove the comparison with literature values owing to the different conditions of reactions frequently to difficult or impossible. (author)

  9. Vapour Phase Hydrogenation of Phenol over Rhodium on SBA-15 and SBA-16

    Directory of Open Access Journals (Sweden)

    Liliana Giraldo

    2014-12-01

    Full Text Available In the present work, mesoporous SBA-15 and SBA-16 were synthesised using classical methods, and their physicochemical properties were investigated by X-ray diffraction (XRD, FTIR, TEM and N2 adsorption–desorption. Rhodium (Rh, 1 wt % was loaded on the mesoporous SBA-15 and SBA-16 by an impregnation method. The Rh surface coverage, dispersion and crystallite size were determined by room temperature H2 chemisorption on reduced samples. The catalytic activity of Rh supported on mesoporous SBA-15 and SBA-16 was evaluated for the first time in the hydrogenation of phenol in vapour phase in a temperature range between 130 and 270 °C at atmospheric pressure. The reaction over Rh/SBA-15 at 180 °C produced cyclohexanone as the major product (about 60% along with lower amounts of cyclohexanol (about 35% and cyclohexane (about 15%. The influences of temperature, H2/phenol ratio, contact time and the nature of the solvent on the catalytic performance were systematically investigated. The Rh/SBA-16 system offered lower phenol conversion compared to Rh/SBA-15, but both have a very high selectivity for cyclohexanone (above 60%.

  10. Electrochemical Intercalation of Lithium Ions into NbSe2 Nanosheets.

    Science.gov (United States)

    Hitz, Emily; Wan, Jiayu; Patel, Anand; Xu, Yue; Meshi, Louisa; Dai, Jiaqi; Chen, Yanan; Lu, Aijiang; Davydov, Albert V; Hu, Liangbing

    2016-05-11

    Transition metal dichalcogenides (TMDCs) have been known for decades to have unique properties and recently attracted broad attention for their two-dimensional (2D) characteristics. NbSe2 is a metallic TMDC that has been studied for its charge density wave transition behavior and superconductivity but is still largely unexplored for its potential use in engineered devices with applications in areas such as electronics, optics, and batteries. Thus, we successfully demonstrate and present evidence of lithium intercalation in NbSe2 as a technique capable of modifying the material properties of NbSe2 for further study. We demonstrate successful intercalation of Li ions into NbSe2 and confirm this result through X-ray diffraction, noting a unit cell size increase from 12.57 to 13.57 Å in the c lattice parameter of the NbSe2 after intercalation. We also fabricate planar half-cell electrochemical devices using ultrathin NbSe2 from platelets to observe evidence of Li-ion intercalation through an increase in the optical transmittance of the material in the visible range. Using 550 nm wavelength light, we observed an increase in optical transmittance of 26% during electrochemical intercalation. PMID:27100021

  11. Thermal analysis and infrared emission spectroscopic study of halloysite-potassium acetate intercalation compound

    International Nuclear Information System (INIS)

    The thermal decomposition of halloysite-potassium acetate intercalation compound was investigated by thermogravimetric analysis and infrared emission spectroscopy. The X-ray diffraction patterns indicated that intercalation of potassium acetate into halloysite caused an increase of the basal spacing from 1.00 to 1.41 nm. The thermogravimetry results show that the mass losses of intercalation the compound occur in main three main steps, which correspond to (a) the loss of adsorbed water, (b) the loss of coordination water and (c) the loss of potassium acetate and dehydroxylation. The temperature of dehydroxylation and dehydration of halloysite is decreased about 100 oC. The infrared emission spectra clearly show the decomposition and dehydroxylation of the halloysite intercalation compound when the temperature is raised. The dehydration of the intercalation compound is followed by the loss of intensity of the stretching vibration bands at region 3600-3200 cm-1. Dehydroxylation is followed by the decrease in intensity in the bands between 3695 and 3620 cm-1. Dehydration was completed by 300 oC and partial dehydroxylation by 350 oC. The inner hydroxyl group remained until around 500 oC.

  12. Intercalation of organic molecules in 2D copper (II) nitroprusside: Intermolecular interactions and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Osiry, H.; Cano, A.; Lemus-Santana, A.A.; Rodríguez, A. [Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Unidad Legaria, Instituto Politécnico Nacional (Mexico); Carbonio, R.E. [INFIQC-CONICET, Departamento de Físico Química, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, X5000HUA Córdoba (Argentina); Reguera, E., E-mail: edilso.reguera@gmail.com [Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Unidad Legaria, Instituto Politécnico Nacional (Mexico)

    2015-10-15

    This contribution discusses the intercalation of imidazole and its 2-ethyl derivative, and pyridine in 2D copper nitroprusside. In the interlayer region, neighboring molecules remain interacting throu gh their dipole and quadrupole moments, which supports the solid 3D crystal structure. The crystal structure of this series of intercalation compounds was solved and refined from powder X-ray diffraction patterns complemented with spectroscopic information. The intermolecular interactions were studied from the refined crystal structures and low temperature magnetic measurements. Due to strong attractive forces between neighboring molecules, the resulting π–π cloud overlapping enables the ferromagnetic coupling between metal centers on neighboring layers, which was actually observed for the solids containing imidazole and pyridine as intercalated molecules. For these two solids, the magnetic data were properly described with a model of six neighbors. For the solid containing 2-ethylimidazole and for 2D copper nitroprusside, a model of four neighbors in a plane is sufficient to obtain a reliable data fitting. - Highlights: • Intercalation of organic molecules in 2D copper (II) nitroprusside. • Molecular properties of intercalation compounds of 2D copper (II) nitroprusside. • Magnetic properties of hybrid inorganic–organic solids. • Hybrid inorganic–organic 3D framework.

  13. Scalable production of graphene with tunable and stable doping by electrochemical intercalation and exfoliation.

    Science.gov (United States)

    Hsieh, Ya-Ping; Chiang, Wan-Yu; Tsai, Sun-Lin; Hofmann, Mario

    2016-01-01

    Graphene's unique semimetallic band structure yields carriers with widely tunable energy levels that enable novel electronic devices and energy generators. To enhance the potential of this feature, a scalable synthesis method for graphene with adjustable Fermi levels is required. We here show that the electrochemical intercalation of FeCl3 and subsequent electrochemical exfoliation produces graphene whose energy levels can be finely tuned by the intercalation parameters. X-ray photoelectron spectroscopy reveals that a gradual transition in the bonding character of the intercalant is the source of this behavior. The intercalated graphene exhibits a significantly increased work function that can be varied between 4.8 eV and 5.2 eV by the intercalation potential. Transparent conducting electrodes produced by these graphene flakes exhibit a threefold improvement in performance and the doping effect was found to be stable for more than a year. These findings open up a new route for the scalable production of graphene with adjustable properties for future applications. PMID:26617396

  14. Intercalation of organic molecules in 2D copper (II) nitroprusside: Intermolecular interactions and magnetic properties

    International Nuclear Information System (INIS)

    This contribution discusses the intercalation of imidazole and its 2-ethyl derivative, and pyridine in 2D copper nitroprusside. In the interlayer region, neighboring molecules remain interacting throu gh their dipole and quadrupole moments, which supports the solid 3D crystal structure. The crystal structure of this series of intercalation compounds was solved and refined from powder X-ray diffraction patterns complemented with spectroscopic information. The intermolecular interactions were studied from the refined crystal structures and low temperature magnetic measurements. Due to strong attractive forces between neighboring molecules, the resulting π–π cloud overlapping enables the ferromagnetic coupling between metal centers on neighboring layers, which was actually observed for the solids containing imidazole and pyridine as intercalated molecules. For these two solids, the magnetic data were properly described with a model of six neighbors. For the solid containing 2-ethylimidazole and for 2D copper nitroprusside, a model of four neighbors in a plane is sufficient to obtain a reliable data fitting. - Highlights: • Intercalation of organic molecules in 2D copper (II) nitroprusside. • Molecular properties of intercalation compounds of 2D copper (II) nitroprusside. • Magnetic properties of hybrid inorganic–organic solids. • Hybrid inorganic–organic 3D framework

  15. Potential-modulated intercalation of alkali cations into metal hexacyanoferrate coated electrodes. 1998 annual progress report

    International Nuclear Information System (INIS)

    'This program is studying potential-driven cation intercalation and deintercalation in metal hexacyanoferrate compounds, with the eventual goal of creating materials with high selectivity for cesium separations and long cycle lifetimes. The separation of radiocesium from other benign cations has important implications for the cost of processing a variety of cesium contaminated DOE wasteforms. This report summarizes results after nine months of work. Much of the initial efforts have been directed towards quantitatively characterizing the selectivity of nickel hexacyanoferrate derivatized electrodes for intercalating cesium preferentially over other alkali metal cations. Using energy dispersive xray spectroscopy (ex-situ, but non-destructive) and ICP analysis (ex-situ and destructive), the authors have demonstrated that the nickel hexacyanoferrate lattice has a strong preference for intercalated cesium over sodium. For example, when ions are reversibly loaded into a nickel hexacyanoferrate thin film from a solution containing 0.9999 M Na+ and 0.0001 M Cs+, the film intercalates 40% as much Cs+ as when loaded from pure 1 M Cs+ containing electrolyte (all electrolytes use nitrates as the common anion). The authors have also shown that, contrary to the common assumptions found in the literature, a significant fraction of the thin film is not active initially. A new near infrared laser has been purchased and is being added to the Raman spectroscopy facilities to allow in-situ studies of the intercalation processes.'

  16. The role of intercalants on the structure and properties of PP/halloysite nanocomposites

    International Nuclear Information System (INIS)

    Complete text of publication follows. In this paper the influence of halloysite structure on the properties of melt-prepared polymer nanocomposites have been studied. Intercalation of halloysite (HLS) carried out in solution as well as by dry mechanochemical method has been investigated by vibrational spectroscopic techniques. Except of currently used modifiers (alkylamines, silanes), an intensive study of organo-clay nanocomplexes (with potassium-acetate, urea, formamide and acetamide) has been investigated and new structural models (as well as reaction pathways) were proposed. It was found that modification of halloysite by alkylamines as well as silanes did not lead to intercalated structure of halloysite. Mechanochemical treatment with urea, however, resulted in an intensive intercalation of halloysite. Surface activation of the mineral has been achieved by the thermal treatment of the complex. The impact of the intercalated structure of halloysite was confirmed by improving mechanical properties, as well as by reduction of flammability of PP/halloysite nanocomposites. The investigation of the structure of polymer nanocomposites based on intercalated halloysite confirmed considerable reduction of particle size and high degree of filler exfoliation. The achieved results confirmed that there is a potential for future utilisation of natural halloysites for production of exfoliated polymer nanocomposites with outstanding end use properties.

  17. INTERPRETATION OF POTENTIAL INTERMITTENCE TITRATION TECHNIQUE EXPERIMENTS FOR VARIOUS Li-INTERCALATION ELECTRODES

    Directory of Open Access Journals (Sweden)

    M.D.Levi

    2002-01-01

    Full Text Available In this paper we compare two different approaches for the calculation of the enhancement factor Wi, based on its definition as the ratio of the chemical and the component diffusion coefficients for species in mixed-conduction electrodes, originated from the "dilute solution" or "lattice gas" models for the ion system. The former approach is only applicable for small changes of the ion concentration while the latter allows one to consider a broad range of intercalation levels. The component diffusion coefficient of lithium ions has been determined for a series of lithium intercalation anodes and cathodes. A new "enhancement factor" for the ion transport has been defined and its relations to the intercalation capacitance and the intercalation isotherm have been established. A correlation between the dependences of the differential capacitance and the partial ion conductivity on the potential has been observed. It is considered as a prove that the intercalation process is controlled by the availability of sites for Li-ion insertion rather than by the concurrent insertion of the counter-balancing electronic species.

  18. Intercalation of urea into kaolinite for preparation of controlled release fertilizer

    Directory of Open Access Journals (Sweden)

    Mahdavi Fariba

    2014-01-01

    Full Text Available In this study urea was intercalated between layers of kaolinite by dry grinding technique to be used for preparing controlled release fertilizer. X-ray powder diffraction (XRPD patterns confirmed the intercalation of urea into kaolinite by the significant expansion of the basal spacing of kaolinite layers from 0.710 nm to 1.090 nm. Fourier transform infrared spectroscopy (FT-IR also confirmed the hydrogen bonding between urea and kaolinite. Based on CHNS elemental analysis, 20% (wt. urea was intercalated between kaolinite layers. The urea-intercalated kaolinite was mixed with hydroxypropyl methylcellulose (HPMC binder and was granulated to prepare the nitrogen-based controlled release fertilizer. To study the nitrogen release behavior of granules, ultraviolet/visible (UV-Vis spectroscopy was used through the diacetyl monoxime (DAM colorimetric method. The result of UV-Vis spectroscopy showed that intercalation of urea into kaolinite decreased the nitrogen release from 25.50 to 13.66 % after 24 hours and from 98.15 to 70.01% after 30 days incubation in water. According to the results, the prepared controlled release fertilizer (CRF behaved according to the standard for CRFs.

  19. Intercalation-assisted longitudinal unzipping of carbon nanotubes for green and scalable synthesis of graphene nanoribbons

    Science.gov (United States)

    Li, Yan-Sheng; Liao, Jia-Liang; Wang, Shan-Yu; Chiang, Wei-Hung

    2016-03-01

    We have demonstrated an effective intercalation of multi-walled carbon nanotubes (MWCNTs) for the green and scalable synthesis of graphene nanoribbons (GNRs) using an intercalation-assisted longitudinal unzipping of MWCNTs. The key step is to introduce an intercalation treatment of raw MWCNTs with KNO3 and H2SO4, making it promising to decrease the strong van der Waals attractions in the MWCNTs bundles and between the coaxial graphene walls of CNTs. Systematic micro Raman, X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) characterizations suggest that potassium, nitrate, and sulfate ions play an important role in the CNT intertube and intratube intercalations during the pretreatment. Detailed scanning electron microscopy (SEM), transmission electron microscopy, XRD, and micro Raman characterizations indicate that the developed methodology possesses the ability to synthesis GNRs effectively with an improved CNT concentration in H2SO4 of 10 mg/ml at 70 °C, which is amenable to industrial-scale production because of the decreased amount of strong acid. Our work provides a scientific understanding how to enhance the GNR formation by accelerating the CNT longitudinal unzipping via suitable molecular intercalation.

  20. Intercalation-assisted longitudinal unzipping of carbon nanotubes for green and scalable synthesis of graphene nanoribbons

    Science.gov (United States)

    Li, Yan-Sheng; Liao, Jia-Liang; Wang, Shan-Yu; Chiang, Wei-Hung

    2016-01-01

    We have demonstrated an effective intercalation of multi-walled carbon nanotubes (MWCNTs) for the green and scalable synthesis of graphene nanoribbons (GNRs) using an intercalation-assisted longitudinal unzipping of MWCNTs. The key step is to introduce an intercalation treatment of raw MWCNTs with KNO3 and H2SO4, making it promising to decrease the strong van der Waals attractions in the MWCNTs bundles and between the coaxial graphene walls of CNTs. Systematic micro Raman, X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) characterizations suggest that potassium, nitrate, and sulfate ions play an important role in the CNT intertube and intratube intercalations during the pretreatment. Detailed scanning electron microscopy (SEM), transmission electron microscopy, XRD, and micro Raman characterizations indicate that the developed methodology possesses the ability to synthesis GNRs effectively with an improved CNT concentration in H2SO4 of 10 mg/ml at 70 °C, which is amenable to industrial-scale production because of the decreased amount of strong acid. Our work provides a scientific understanding how to enhance the GNR formation by accelerating the CNT longitudinal unzipping via suitable molecular intercalation. PMID:26948486

  1. Kaolinite Nanocomposite Platelets Synthesized by Intercalation and Imidization of Poly(styrene-co-maleic anhydride

    Directory of Open Access Journals (Sweden)

    Pieter Samyn

    2015-07-01

    Full Text Available A synthesis route is presented for the subsequent intercalation, exfoliation and surface modification of kaolinite (Kln by an imidization reaction of high-molecular weight poly(styrene-co-maleic anhydride or SMA in the presence of ammonium hydroxide. In a first step, the intercalation of ammonolyzed SMA by guest displacement of intercalated dimethylsulfoxide has been proven. In a second step, the imidization of ammonolyzed SMA at 160 °C results in exfoliation of the kaolinite layers and deposition of poly(styrene-co-maleimide or SMI nanoparticles onto the kaolinite surfaces. Compared with a physical mixture of Kln/SMI, the chemically reacted Kln/SMI provides more efficient exfoliation and hydrogen bonding between the nanoparticles and the kaolinite. The kaolinite nanocomposite particles are synthesized in aqueous dispersion with solid content of 65 wt %. The intercalation and exfoliation are optimized for a concentration ratio of Kln/SMI = 70:30, resulting in maximum intercalation and interlayer distance in combination with highest imide content. After thermal curing at 135 °C, the imidization proceeds towards a maximum conversion of the intermediate amic acid moieties. The changes in O–H stretching and kaolinite lattice vibrations have been illustrated by infrared and FT-Raman spectroscopy, which allow for a good quantification of concentration and imidization effects.

  2. Consolidation Radiotherapy in Stage IE- IIE, Non-Bulky Primary Gastric Diffuse Large B-Cell Lymphoma with Post-Chemotherapy Complete Remission.

    Directory of Open Access Journals (Sweden)

    Qiwen Li

    Full Text Available To investigate the effects of consolidation radiation in patients with stage IE-IIE, non-bulky primary gastric diffuse large B-cell lymphoma (DLBCL.A cohort consisted of 71 consecutive patients with stage IE-IIE, non-bulky primary gastric DLBCL was retrospectively analyzed. All of them had been in complete remission after receiving at least four cycles of chemotherapy, containing rituximab or not. Consolidation radiation was delivered thereafter in 28 patients while other 43 received clinical observation only. Locoregional relapse-free survival (LRFS, disease-free survival (DFS, overall survival (OS and distant metastasis-free survival (DMFS were compared between patients with or without radiotherapy.The 10-year LRFS, DFS, OS and DMFS were 100% and 81.4% (p = 0.028, 91.7% and 77.1% (p = 0.14, 91.7% and 77.8% (p = 0.67, 91.7% and 78.0% (p = 0.42 for patients with or without radiotherapy.Radiotherapy is associated with improved locoregional control of patients with early stage primary gastric DLBCL, who have achieved complete remission following at least four cycles of chemotherapy.

  3. Preparation of association compound between rhodium(II) citrate and {beta}-cyclodextrin; Preparacao do composto de associacao entre citrato de rodio(II) e {beta}-ciclodextrina

    Energy Technology Data Exchange (ETDEWEB)

    Burgos, Ana E.; Okio, Coco K.Y.A., E-mail: aeburgosc@unal.edu.co [Departamento de Quimica, Universidad Nacional de Colombia, Bogota (Colombia); Sinisterra, Ruben D. [Departamento de Quimica, Instituto de Ciencias Exatas, Universidade Federal de Minas Gerais, Belo Horizonte - MG (Brazil)

    2012-07-01

    Inclusion compound of rhodium(II) citrate with{beta}-cyclodextrin in a 1:1 molar ratio was prepared using freeze-drying method. X-ray diffractometry, thermal analysis (TG/DTG/DSC), infrared and {sup 1}H-NMR with {sup 1}H spin lattice relaxation ({sup 1}H T{sub 1}) measurements and {sup 13}C techniques were used to characterize the system prepared. The results indicated the formation of inclusion or association compounds between rhodium(II) citrate and {beta}-cyclodextrin. (author)

  4. First-principle study of silicon cluster doped with rhodium: Rh2Sin (n = 1–11) clusters

    International Nuclear Information System (INIS)

    The geometries, stabilities and electronic properties of rhodium-doped silicon clusters Rh2Sin (n = 1–11) have been systematically studied by using density functional calculations at the B3LYP/GENECP level. The optimized results show that the lowest-energy isomers of Rh2Sin clusters favor three-dimensional structures for n = 2–11. Based on the averaged binding energy, fragmentation energy, second-order energy difference and HOMO-LUMO energy gap, the stabilities of Rh2Sin (n = 1–11) clusters have been analyzed. The calculated results suggest that the Rh2Si6 cluster has the strongest relative stability and the doping with rhodium atoms can reduce the chemical stabilities of Sin clusters. The natural population and natural electron configuration analysis indicate that there is charge transfer from the Si atoms and 5s orbital of the Rh atoms to the 4d and 5p orbitals of Rh atoms. The analysis of electron localization function reveal that the Si–Si bonds are mainly covalent bonds and the Si–Rh bonds are almost ionic bonds. Moreover, the vertical ionization potential, vertical electron affinity, chemical hardness, chemical potential, vibrational spectrum and polarizability are also discussed. - Highlights: • The geometric structures of Rh2Sin (n = 1–11) clusters are determined. • The stabilities and electronic properties of Rh2Sin clusters are discussed. • The Rh2Si6 cluster has the higher stability than other clusters. • The doped rhodium atoms can reduce the chemical stabilities of Sin clusters

  5. Radiosensitization by the novel DNA intercalating agent vosaroxin

    International Nuclear Information System (INIS)

    Vosaroxin is a first in class naphthyridine analog structurally related to quinolone antibacterials, that intercalates DNA and inhibits topoisomerase II. Vosaroxin is not a P-glycoprotein receptor substrate and its activity is independent of p53, thus evading common drug resistance mechanisms. To evaluate vosaroxin as a clinically applicable radiation sensitizer, we investigated its effects on tumor cell radiosensitivity in vitro and in vivo. Vosaroxin's effect on post-irradiation sensitivity of U251, DU145, and MiaPaca-2 cells was assessed by clonogenic assay. Subsequent mechanistic and in vivo studies were performed with U251 cells. Cell cycle distribution and G2 checkpoint integrity was analyzed by flow cytometry. DNA damage and repair was evaluated by a high throughput gamma-H2AX assay. Apoptosis was assessed by flow cytometry. Mitotic catastrophe was assessed by microscopic evidence of fragmented nuclei by immunofluorescence. In vivo radiosensitization was measured by subcutaneous tumor growth delay. 50-100 nmol/L treatment with vosaroxin resulted in radiosensitization of all 3 cell lines tested with a dose enhancement factor of 1.20 to 1.51 measured at a surviving fraction of 0.1. The maximal dose enhancement was seen in U251 cells treated with 75 nmol/L vosaroxin (DEF 1.51). Vosaroxin exposure did not change cell cycle distribution prior to irradiation nor alter G2 checkpoint integrity after irradiation. No difference was seen in the apoptotic fraction regardless of drug or radiation treatment. The number of cells in mitotic catastrophe was significantly greater in irradiated cells treated with vosaroxin than cells receiving radiation only at 72 hr (p = 0.009). Vosaroxin alone did not significantly increase mitotic catastrophe over control (p = 0.53). Cells treated with vosaroxin and radiation maintained significantly higher gamma-H2AX levels than cells treated with vehicle control (p = 0.014), vosaroxin (p = 0.042), or radiation alone (p = 0.039) after

  6. Synthesis and Characterization of Ibuprofen-Rectorite Composites by Solution Intercalation Method

    Institute of Scientific and Technical Information of China (English)

    WANG Huiyan; ZHANG Gaoke; GAN Huihu; GAO Yuanyuan

    2009-01-01

    The ibuprofen-rectorite composites were prepared by the solution intercalation method using ibuprofen and rectorite as raw materials,and were characterized by X-ray diffraction (XRD)analysis,Fourier transform infrared analysis and scanning electron microscopy(SEM).The experimental results show that the ibuprofen is intercalated into the interlayer spaces of rectorite.The values of the(001)peaks of the ibuprofen-rectorite composite are larger than that of Na-rectorite and reach the largest when the reaction time and ibuprofen amount is 2 h and 0.36 g,respectively.The layered structure of Na-rectorite is destroyed to some extent with the intercalation of ibuprofen into the interlayer space in the structure of Na-rectorite.A part of ibuprofen in the ibuprofen Na-rectorite covers on the surface of Na-rectorite besides some ibuprofen enters into the interlayer space.

  7. Electron doping through lithium intercalation to interstitial channels in tetrahedrally bonded SiC

    International Nuclear Information System (INIS)

    We report on first-principles calculations that clarify the effect of lithium atom intercalation into zinc blende 3C-silicon carbide (3C-SiC) on electronic and structural properties. Lithium atoms inside 3C-SiC are found to donate electrons to 3C-SiC that is an indication of a new way of electron doping through the intercalation. The electrons doped into the conduction band interact with lithium cations and reduce the band spacing between the original valence and conduction bands. We have also found that a silicon monovacancy in 3C-SiC promotes the lithium intercalation, showing that the vacancy generation makes SiC as a possible anode material for lithium-ion battery

  8. Preparation of poly(propylene carbonate)/organophilic rectorite nanocomposites via direct melt intercalation

    Institute of Scientific and Technical Information of China (English)

    WAN Chun-jie; YU Jian-ying; SHI Xiao-jian; HUANG Li-hua

    2006-01-01

    The completely degradable nanocomposites comprised of poly(propylene carbonate)(PPC) and organo-modified rectorite (OREC) were prepared by direct melt intercalation. The structure and mechanical properties of PPC/OREC nanocomposites were investigated. The wide-angle X-ray diffraction (WAXD) results show that the galleries distance of OREC is increased after PPC and OREC melt intercalation,which indicates that PPC molecular chain has intercalated into the layers of OREC. The PPC/OREC nanocomposites with lower OREC content show an increase in thermal decomposition temperature compared with pure PPC. The tensile strength and impact strength of PPC/OREC nanocomposites are improved. When the mass fraction of OREC is 4%,the tensile strength and impact strength of the PPC/OREC nanocomposite increase by 22.86% and 48.58% respectively,compared with pure PPC.

  9. Intercalation of diclofenac in modified Zn/Al hydrotalcite-like preparation

    Science.gov (United States)

    Heraldy, E.; Suprihatin, R. W.; Pranoto

    2016-02-01

    The intercalation of a pharmaceutically active material diclofenac into modified Zn/Al Hydrotalcite-like (Zn/Al HTlc) preparation has been investigated by the coprecipitation and ion exchange method, respectively. The synthetic materials were characterized using X- Ray Diffraction (XRD); Fourier transforms infrared spectroscopy (FTIR); Scanning Electron Microscope (SEM); X-Ray Fluorescence (XRF) and surface area analyzer. The results show that the basal spacing of the product was expanded to 11.03 A for direct synthesis and 10.68 A for indirect synthesis, suggesting that diclofenac anion was intercalated into Zn/Al HTlc and arranged in a tilted bilayer fashion and the specific surface area of material increased after the intercalation of diclofenac.

  10. Preparation of the Thermoplastic Starch/Montmorillonite Nanocomposites by Melt-intercalation

    Institute of Scientific and Technical Information of China (English)

    Ming Fu HUANG; Jiu Gao YU; Xiao Fei MA

    2005-01-01

    In this paper, the conception of melt-intercalation was introduced into the natural polymer field, and the thermoplastic starch/ethanolamine-activated montmorillonite (TPS/EMMT)nanocomposites were prepared by extruding the composites of EMMT and TPS, plasticized with ethanolamine/formamide. Wide angle X-ray diffraction (WAXD) and transmission electron microscope (TEM) revealed that TPS was intercalated into the layers of EMMT successfully and formed the intercalation nanocomposites with EMMT. When EMMT content was wt. 10%, the mechanical testing indicated that the tensile stress of the nanocomposites reached 9.69 MPa, and the tensile strain reached 74.07%, Youngs modulus increased from the 47.23 MPa of TPS to 184.11after they had been stored at RH25% for 14 days.

  11. Electron doping through lithium intercalation to interstitial channels in tetrahedrally bonded SiC

    Energy Technology Data Exchange (ETDEWEB)

    Sakai, Yuki [Department of Applied Physics, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Center for Computational Materials, Institute for Computational Engineering and Sciences, The University of Texas at Austin, Austin, Texas 78712 (United States); Oshiyama, Atsushi [Department of Applied Physics, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2015-11-07

    We report on first-principles calculations that clarify the effect of lithium atom intercalation into zinc blende 3C-silicon carbide (3C-SiC) on electronic and structural properties. Lithium atoms inside 3C-SiC are found to donate electrons to 3C-SiC that is an indication of a new way of electron doping through the intercalation. The electrons doped into the conduction band interact with lithium cations and reduce the band spacing between the original valence and conduction bands. We have also found that a silicon monovacancy in 3C-SiC promotes the lithium intercalation, showing that the vacancy generation makes SiC as a possible anode material for lithium-ion battery.

  12. Thermoelectric Properties of Li-Intercalated ZrSe2 Single Crystals

    DEFF Research Database (Denmark)

    Holgate, Tim; Liu, Yufei; Hitchcock, Dale;

    2013-01-01

    can profoundly affect the structural, thermal, and electronic properties of such materials. While the thermoelectric potential of layer-structured transitionmetal dichalcogenides has been formerly studied by several groups, to our best knowledge, neither the thermoelectric properties of ZrSe2 nor...... the impact of intercalation on its thermoelectric properties have been reported (specifically, the full evaluation of the dimensionless figure of merit, ZT, which includes the thermal conductivity). In this proof-of-principle study, ZrSe2 single crystals have been synthesized using an iodine-assisted vapor...... transport method, followed by a wet-chemistry lithium intercalation process. The results of resistivity, thermopower, and thermal conductivity measurements between 10 K and 300 K show that Li intercalation induced additional charge carriers and structural disorder that favorably affected the thermoelectric...

  13. Superconductivity in copper intercalated topological compound CuxBi2Te3 induced via high pressure

    International Nuclear Information System (INIS)

    Highlights: • Superconductivity was found in Cu intercalated Bi2Te3 topological insulators induced via pressures. • The copper atoms are intercalated between Te(2) and Te(2) layers confirmed by X-ray diffraction experiment. • The superconductivity of Cu0.14Bi2Te3 occurs before the pressure point of the structural transition. -- Abstract: Copper intercalated Bi2Te3 topological single crystal Cu0.14Bi2Te3 was grown using Bridgman method. The transport properties were studied by temperature dependent resistance measurements at various pressures. Pressure induced superconductivity was found with Tc for ambient phase ∼6 K. The evolutions of crystal structure with pressure were investigated by high pressure synchrotron radiation experiments that reveal structural transitions occurring above 9.8 GPa. The superconducting properties of Cu0.14Bi2Te3 are compared with that of undoped topological compound Bi2Te3

  14. Structure model and synthesis of NdCl3-FeCl3-graphite intercalation compounds

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The distribution of the elements and microstructure of NdCl3-FeCl3-graphite intercalation compounds (GICs) were shown by scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). The results show that Nd element intercalates into graphite, forming NdCl3-FeCl3-GICs, and the distribution of Nd and Fe is nearly even. On the basis of the data, a structure model for RECl3-GICs was founded, and the characteristic layer distance and the index of interval energy were calculated. The calculated results agree with experimental ones, and the relative errors are ±2%. Thus it can be seen that the (111) face is optimal direction for intercalation reaction of TbCl3 LuCl3, and the (001) face is that for LaCl3 GdCl3, because of the lowest interval energy.

  15. Structure model and synthesis of NdCl3-FeCl3-graphite intercalation compounds

    Institute of Scientific and Technical Information of China (English)

    侯仰龙[1; 韦永德[2; 石建新[3

    2000-01-01

    The distribution of the elements and microstructure of NdCI3-FeCI3-graphite intercalation compounds (GICs) were shown by scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). The results show that Nd element intercalates into graphite, forming NdCI3-FeCI3-GICs, and the distribution of Nd and Fe is nearly even. On the basis of the data, a structure model for RECI3-GICs was founded, and the characteristic layer distance and the index of interval energy were calculated. The calculated results agree with experimental ones, and the relative errors are ±2%. Thus it can be seen that the (111) face is optimal direction for intercalation reaction of TbCl3-LuCl3, and the (001) face is that for LaCl3-GdCl3, because of the lowest interval energy.

  16. AB INITIO STUDY OF CHEMICAL ACTIVATION AND HYDROGENATION OF WHITE PHOSPHORUS IN REACTION WITH RHODIUM TRIHYDRIDE COMPLEX

    OpenAIRE

    Iolanta I. Balan; Natalia N. Gorinchoy

    2011-01-01

    The four-stage mechanism of reaction of the rhodium trihydride complex [(triphos)RhH3] (triphos=1,1,1-tris(diphenylphosphanylmethyl)ethane) with the white phosphorus molecule resulting in the phosphane and the cyclo-P3 complex [(triphos)M(η3-P3] is analyzed on the basis of ab initio calculations of reactants, products, and intermediate complexes of reaction. It is shown that generation of the transient complex [(triphos)RhH(η1:η1-P4)] followed by intramolecular hydrogen atom migration from t...

  17. Construction of Cyclic Sulfamidates Bearing Two gem-Diaryl Stereocenters through a Rhodium-Catalyzed Stepwise Asymmetric Arylation Protocol.

    Science.gov (United States)

    Zhang, Yu-Fang; Chen, Diao; Chen, Wen-Wen; Xu, Ming-Hua

    2016-06-01

    A rhodium-catalyzed stepwise asymmetric 1,4- and 1,2-addition of arylboronic acids to α,β-unsaturated cyclic N-sulfonyl ketimines has been developed, providing a wide range of gem-diaryl-substituted chiral benzosulfamidates with high optical purities. C1-Symmetric chiral diene and branched chiral sulfur-olefin ligands were sequentially utilized in this double-arylation process for high stereocontrol. Further synthetic utility offers new opportunities for the facile construction of otherwise difficult to access polycyclic heterocycles. PMID:27184663

  18. Regiospecific tritium labeling of aromatic acids, amides, amines and heterocyclics using homogeneous rhodium trichloride and ruthenium acetylacetonate catalysts

    International Nuclear Information System (INIS)

    Homogeneous rhodium trichloride has been found to promote ortho-tritiation with high regioselectivity in a wide range of aromatic carboxylic acids, amides and aralkylamines. Less successful results were obtained using o-chlorobenzoic and o-anisic acids where some decomposition was seen, and in acids and amides of the phenolic type, where a degree of electrophilic exchange accompanies the ortho-exchange. The same catalyst has also been used to regiospecifically label a number of heterocyclics. In the course of investigations with other metal complexes ruthenium acetylacetonate has been identified as an excellent promoter of ortho-exchange in benzoic acids. (author)

  19. Hydroxy double salts loaded with bioactive ions: Synthesis, intercalation mechanisms, and functional performance

    Science.gov (United States)

    Kaassis, Abdessamad Y. A.; Xu, Si-Min; Guan, Shanyue; Evans, David G.; Wei, Min; Williams, Gareth R.

    2016-06-01

    The intercalation of the anions of diclofenac (Dic), naproxen (Nap), and valproic acid (Val) into three hydroxy double salts (HDSs) has been explored in this work. Experiments were performed with [Co1.2Zn3.8(OH)8](NO3)2·2H2O (CoZn-NO3), [Ni2Zn3(OH)8](NO3)2·2H2O (NiZn-NO3) and [Zn5(OH)8](NO3)2·2H2O (Zn-NO3). It proved possible to intercalate diclofenac and naproxen into all three HDSs. In contrast, Val could be intercalated into CoZn-NO3 but when it was reacted with Zn-NO3 the HDS structure was destroyed, and the product comprised ZnO. Successful intercalation was verified by X-ray diffraction, IR spectroscopy, and elemental microanalysis. Molecular dynamics simulations showed the Dic and Nap ions to arrange themselves in an "X" shape in the interlayer space, forming a bilayer. Val was found to adopt a position with its aliphatic groups parallel to the HDS layer, again in a bilayer. In situ time resolved X-ray diffraction experiments revealed that intercalation of Dic and Nap into CoZn-NO3 and Zn-NO3 is mechanistically complex, with a number of intermediate phases observed. In contrast, the intercalation of all three guests into NiZn-NO3 and of Val into CoZn-NO3 are simple one step reactions proceeding directly from the starting material to the product. The HDS-drug composites were found to have sustained release profiles.

  20. Intercalation behavior of poly(ethylene glycol) in organically modified montmorillonite

    Science.gov (United States)

    Zhu, Shipeng; Peng, Hongmei; Chen, Jinyao; Li, Huilin; Cao, Ya; Yang, Yunhua; Feng, Zhihai

    2013-07-01

    In this paper, two kinds of organically modified montmorillonite (OMMT) were prepared using alkylammonium surfactants with different alkyl chain numbers. XRD results showed the interlayer spacing of OMMT increased with low concentration surfactants. With further increasing the surfactants concentration, the interlayer spacing of OMMT was unchanged. Meanwhile, FTIR was used to characterize the local environments of surfactants in the interlayer space of OMMT. The results suggested that the double chain surfactant D-18 preferred to adopt highly ordered conformation compared with single chain surfactant S-18 in interlayer space of OMMT. It indicated that the surface property of the OMMT is affected by the concentration and configuration of the intercalated surfactants. Moreover, the effect of the OMMT type, or more particularly the chemical nature of the organic modifier in the interlayer spacing and the poly(ethylene glycol) (PEG) concentration onintercalation behavior of PEG chains in OMMT were investigated with XRD and DSC.The results indicated that PEG chains could not intercalate into Na-MMT when the surfactants were saturated in interlayer space of Na-MMT. PEG chains could intercalate into the interlayer space of SM when the S-18 concentration was lower than 2.00CEC, implying that the low surfactant concentration modified SM provided a better environment (presumably through the balanced hydrophobic and hydrophilic surfaces) for the PEG intercalation as well. However, PEG did not intercalate into the interlayer space of DM when the D-18 concentration was higher than 1.00CEC. It could be attributed to the hydrophobic double alkyl chains of DM increased with D-18. The increased hydrophobic properties in the interlayer space of 1.50DM hybrids can prevent the intercalation of hydrophilic PEG.

  1. Eu3+ luminescence enhancement by intercalation of benzenepolycarboxylic guests into Eu3+-doped layered gadolinium hydroxide

    International Nuclear Information System (INIS)

    Graphical abstract: Two benzenepolycarboxylic sensitizers, 1,3,5-benzenetricarboxylic acid (BTA) and 1,2,4,5-benzenetetracarboxylic acid (BA), were intercalated into NO3–LGdH:Eu, in which different structures of the compounds resulted in varied arrangement in the gallery. The two organic compounds especially BA markedly enhanced the red luminescence of Eu3+ due to efficient energy transfer between the organic guests and Eu3+ centers. - Highlights: • We report the intercalation of benzenepolycarboxylic organic sensitizers into LRH. • We study the intercalation structure and the arrangement of the interlayer guests. • The two organic compounds can markedly enhance the luminescence of Eu3+. • There exists efficient energy transfer between organic guests and Eu3+ centers. • This material opens a route for fabricating new multifunctional luminescent materials. - Abstract: Two benzenepolycarboxylic organic sensitizers, 1,3,5-benzenetricarboxylic acid (BTA) and 1,2,4,5-benzenetetracarboxylic acid (BA), were intercalated into the gallery of NO3− type Eu3+-doped layered gadolinium hydroxide (NO3–LGdH:Eu). CHN analysis, FTIR, and SEM were employed to characterize the intercalation structures of the as-prepared organic/inorganic hybrids. The area per unit charge (Scharge) was used to explain the intercalation structure and the arrangement of the interlayer guests. Different structures of the two organic compounds resulted in varied arrangement of guests. Photoluminescence studies indicated that both of the two organic compounds especially BA markedly enhanced the red luminescence of Eu3+ due to efficient energy transfer between the organic guests and Eu3+ centers

  2. Adsorption and intercalation of anionic surfactants onto layered double hydroxides—XRD study

    Indian Academy of Sciences (India)

    R Anbarasan; W D Lee; S S Im

    2005-04-01

    Layered double hydroxides (LDH) with brucite like structure was modified with various anionic surfactants containing sulfonate, carboxyl, phosphonate and sulfate end group through ion-exchange method. XRD reports indicated that the sulfonate group containing surfactants led to an adsorption process whereas the sulfate, carboxyl and phosphonate group containing surfactant led to an intercalation process. This can be evidenced from the change in basal spacing of LDH. The presence of anionic surfactants in the LDH was supported by FTIR spectroscopy. The FTIR spectrum indicated that complete removal of carbonate anion from the inter layer space of LDH is very difficult. The phosphonate intercalated HT showed less thermal stability than pristine LDH.

  3. Synthesis of intercalated compounds of aluminium hydroxide and lithium salts containing EDTA anions

    International Nuclear Information System (INIS)

    Interaction of an intercalation compound of aluminium hydroxide of the composition LiCl·2Al(OH)3·pH2O with aqueous solution of EDTA sodium salts at different pH values is studied by IR spectroscopy, chemical and X-ray phase analyses. Formation of intercalation c compounds of aluminium hydroxide LinH4-nEDTA·mAl(OH)3·pH2O is ascertained. 5 refs., 2 figs., 1 tab

  4. Synthesis, characterization and properties of polyaniline/expanded vermiculite intercalated nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Lin Jianming; Tang Qunwei; Wu Jihuai; Sun Hui [Key Laboratory of Functional Materials for Fujian Higher Education, Institute of Material Physical Chemistry, Huaqiao University, Quanzhou 362021 (China)], E-mail: jhwu@hqu.edu.cn

    2008-04-15

    The synthesis characterization and conductivities of polyaniline/expanded vermiculite intercalated nanocomposite are presented in this paper. The conductive emeraldine salt form of polyaniline is inserted into the interlayer of expanded vermiculite to produce the nanocomposite with high conductivity. The structures and properties are characterized by transmission electron microscopy x-ray diffraction spectroscopy fourier transform infrared spectroscopy thermogravimetry analysis and by the measurements of conductivity and stability. The results show that an intercalated nanocomposite with high conductivity and stability is obtained. The synthesis conditions are optimized to obtain the highest conductivity which is 6.80 S cm{sup -1}.

  5. Synthesis, characterization and properties of polyaniline/expanded vermiculite intercalated nanocomposite

    Directory of Open Access Journals (Sweden)

    Jianming Lin, Qunwei Tang, Jihuai Wu and Hui Sun

    2008-01-01

    Full Text Available The synthesis characterization and conductivities of polyaniline/expanded vermiculite intercalated nanocomposite are presented in this paper. The conductive emeraldine salt form of polyaniline is inserted into the interlayer of expanded vermiculite to produce the nanocomposite with high conductivity. The structures and properties are characterized by transmission electron microscopy x-ray diffraction spectroscopy fourier transform infrared spectroscopy thermogravimetry analysis and by the measurements of conductivity and stability. The results show that an intercalated nanocomposite with high conductivity and stability is obtained. The synthesis conditions are optimized to obtain the highest conductivity which is 6.80 S cm−1.

  6. THE NANOCOMPOSITE FILM OF POLYMER INTERCALATION IN V2O5 XEROGEL

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The nanocomposite films were prepared by poly(ethylene oxide), PEO, intercalation in V2O5 xerogel in sol-gel. The synthesis and state of the films are investigated by the XRD, IR, SEM, etc. The results show that V2O5 xerogel is a layered structure which arranges in c-direction. The interlayer distance of V2O5 xerogel increases remarkably when PEO is intercalated in V2O5 xerogel interlayer. PEO has strong interaction with V2O5 host. The surface of the films is homogeneous without holes and cracks.

  7. Optimal design of parallel triplex forming oligonucleotides containing Twisted Intercalating Nucleic Acids--TINA

    DEFF Research Database (Denmark)

    Schneider, Uffe V; Mikkelsen, Nikolaj D; Jøhnk, Nina;

    2010-01-01

    Twisted intercalating nucleic acid (TINA) is a novel intercalator and stabilizer of Hoogsteen type parallel triplex formations (PT). Specific design rules for position of TINA in triplex forming oligonucleotides (TFOs) have not previously been presented. We describe a complete collection of easy...... on PT is remarkably high (between 7.4 and 15.2 degrees C) compared to antiparallel duplexes (between 3.8 and 9.4 degrees C). The specificity of PT by Delta T(m) increases when shorter TFOs and higher pH are chosen. To increase Delta Tms, base mismatches should be placed in the center of the TFO and...

  8. NBR/ORGANOMODIFIED BENTONITE INTERCALATED HYBRIDS AND THEIR EFFECTS ON THE TOUGHNESS OF PVC

    Institute of Scientific and Technical Information of China (English)

    Chang-jiang You; De-min Jia; Zeng-yong Zhen; Kui Ding; Song Xi; Hai-lin Mo; Yong-hua Zhang

    2003-01-01

    Hybrids of intercalative nitrile-butadiene rubber/organomodified bentonite (NBR/OMB) were prepared by the latex intercalation technique. Investigation of their mechanical properties and the microstructure of NBR/OMB showed that the organomodified bentonite is an effective toughener for NBR. Transmission electronic microscopy (TEM) and X-ray diffraction (XRD) tests showed that the NBR macromolecule could be intercalated into the galleries of bentonite.Incorporation of NBR/OMB hybrids as tougheners into poly(vinyl chloride) (PVC) results in a substantial increase in the impact strength of PVC, but little decrease in its tensile strength and flexural strength, compared to the unmodified PVC.

  9. Strong anisotropic superconducting behavior in the dichalcogenide SnSe2 intercalated with cobaltocene

    International Nuclear Information System (INIS)

    We present a detailed study of the layered dichalcogenide SnSe2 intercalated with the organometallic donor molecule cobaltocene, which exhibits a superconducting transition at Tc=6 K. The extremely anisotropic superconducting behavior is reflected by an in-plane and off-plane resistivity, which deviate from each other by a factor of 200 just before superconductivity sets in. Furthermore, this strong anisotropy leads to two different superconducting transition temperatures, one goes in line with the in-plane and the other with the off-plane superconductivity. In addition, specific heat studies clearly characterize the intercalated SnSe2 as a bulk superconductor with these two different Tc's. (orig.)

  10. Ab initio investigation of the Jahn-Teller distortion effect on the stabilizing lithium intercalated compounds

    International Nuclear Information System (INIS)

    This paper reports on a fundamental study of the Jahn-Teller distortion effect after lithium intercalation in transition metal oxides, using the density functional theory in the local spin density approximation. The intercalation of lithium in cobalt oxide was found to form a stable compound with an α-NaFeO2 crystal structure. An unstable structure was found to form for the nickel oxide compound. An important Jahn-Teller distortion was observed in MnO2 and LiMnO2, and the structure was found to be unstable. These theoretical results are in agreement with the experimental findings in the literature

  11. Hydrogenation of CO and CO2 over rhodium catalysts supported on various metal oxides

    International Nuclear Information System (INIS)

    The formation of hydrocarbons in the reaction of CO + H2 and CO2 + H2 was studied over rhodium catalysts supported on ZrO2, Al2O3, SiO2, and MgO. Among those catalysts, Rh on ZrO2 was most active and Rh-MgO was least active for the above reactions. Over Rh-ZrO2, the CO2 + H2 reaction took place even at 500C, whereas the CO + H2 reaction occurred only at temperature higher than 1300C. The reaction of CO2 + H2 produced only methane at temperatures up to 2000C, but a small amount of CO formed along with methane in the reverse water gas shift reaction above 2000C. In the case of the CO + H2 reaction, the higher molecular weight hydrocarbons (C2 approx. C4) as well as CH4 formed. The inverse kinetic isotope effect was observed in both reactions of CO + H2(D2) and CO2 + H2(D2) over Rh-ZrO2. However, the isotope effect was not observed in the CO2 + H2(D2) reaction over Rh-Al2O3 whose effect in the CO + H2 reaction was still inverse. The activity for the CO + H2 reaction over the oxidized Rh-ZrO2 and Rh-Al2O3 was almost 2 to 10 times higher than that on the reduced catalyst. The reaction mechanisms of the above reactions are discussed. 2 figures, 4 tables

  12. The characterization of rhodium-105 (105RhCl3) for therapeutic applications

    International Nuclear Information System (INIS)

    Rhodium-105 (105Rh) is one of the radioisotopes that has favourable physical characteristics for therapy, i.e. as β-particles emitter having t1/2 = 35.4 h, Eβ = 247 keV (30%) and 560 keV (70%). In addition to the β - particles, 105Rh also emits γ - rays of 306 keV (5%) and 319 keV (19%). Those energies range are also suitable for imaging during therapeutic applications. The physical and chemical characteristics of 105Rh (105RhCl3) had been studied. It consists of: pH, solution clarity, the radiochemical purity that was determined by paper chromatography and paper electrophoresis techniques, the activity as well as radionuclidic purity that were determined by using multi channel γ-ray spectrometer (MCA), the chemical purity was analyzed by determination the unreacted target (104Ru) concentration using spot test method, and finally the physical and chemical stabilities. The obtained solution of 105RhCl3 having the radiochemical purity of 98.61 ± 0.53% and radionuclidic purity more than 95% (99.78 ± 0.03%). The solution has the pH of 1.5 - 2, clear, with the activity of 35 - 60 mCi, radioactive concentration of 7 - 12 mCi/mL and the concentration of unirradiated 104Ru was less than 50 ppm. Stability evaluation indicated that 105RhCl3 solution was still stable for 6 days at room temperature with the radiochemical purity more than 95%. (author)

  13. Adducts of Amine with Dimeric Rhodium(II) Tetracarboxylates - Formation of Nitrogenous Chiral Center

    International Nuclear Information System (INIS)

    Rhodium(II) tetracarboksylates Rh2(RCO2)4 (1a) are able to produce various complexes with organic ligands, like the 1:1 and 2:1 adducts containing axially bonded ligands (1b), or the compounds with rearranged dirhodium core (1c). The solution of dirhodium(II) tetracarboxylate and a ligand usually contains a mixture of adducts, due to ligand exchange and different equilibriums between species. However, application of nuclear magnetic resonance measurements at reduced temperature allows often observing the signals of all species in the solution. Ligands containing nitrogen atom were the subject of our previous investigation. It was found that dirhodium salts are able to form both 1:1 and 2:1 adducts with an amine, depending on reagents ratio. The present investigations are devoted to the amines with general formula NRR'R', is the amines having potential nitrogenous chiral center. An amine with three various substituents NRR'R' is formally a chiral molecule, but in the solution the molecule forms racemic mixture due to fast pyramidal inversion at the nitrogen atom. However, dirhodium(II) tetracarboxylates bonding the amine acts as an agent freezing pyramidal inversion at nitrogen atom, and results in formation of a new, nitrogenous chiral center in the adduct. Thus, the chiral dirhodium salt (4R)-Rh2[(CF3)(OCH3)(Ph)CO2]4 forms with benzyl-ethyl-methylamine five adducts: (4R)/(S), (4R)/(R) (1:1 adducts) and (R)/(4R)/(R), (R)/(4R)/(S), (S)/(4R)/(S) (2:1 adducts). All these diastereoisomers were detected by means of low temperature NMR (253 K). Similar effect was observed for the adducts with methyl-(1-phenylethyl)- amine, PhCH(NHCH3)CH3, having both nitrogenous and carbon chiral centers. (author)

  14. Phosphaalkene-oxazoline copolymers with styrene as chiral ligands for rhodium(I).

    Science.gov (United States)

    Serin, Spencer C; Dake, Gregory R; Gates, Derek P

    2016-04-01

    The radical-initiated copolymerization of phosphaalkene-oxazoline, MesP[double bond, length as m-dash]C(Ph)CMe2Ox [1, Ox = CNOCH(iPr)CH2] with different loadings of styrene affords poly(methylenephosphine-co-styrene)s [2a (1 : S = 1 : 2): Mw = 7400 g mol(-1), PDI = 1.1; 2b (1 : S = 1 : 5): Mw = 18 000 g mol(-1), PDI = 1.2; 2c (1 : S = 1 : 10): Mw = 16 000 g mol(-1), PDI = 1.3]. Copolymers 2a-2c are demonstrated as viable macromolecular ligands for rhodium(i). By comparison with the crystallographically characterized model P,N-bidentate complex, [Mes(Me)P-CH(Ph)CMe2Ox·Rh(cod)]BF4, the polymer complexes [2·Rh(cod)]BF4 were prepared. The macromolecular metal complexes were characterized by GPC {for [2a·Rh(cod)]BF4: Mw = 14 000 g mol(-1), PDI = 1.2}, UV/Vis spectroscopy, (1)H, (13)C and (31)P NMR spectroscopy. Integration of the (31)P NMR spectra of mixtures of 2 and [Rh(cod)2]BF4 permitted the determination of the mol% of incorporation of monomer 1 in copolymer 2 (2a: 17%; 2b: 5%; 2c: 4%). These results compared favorably with those determined by elemental analysis (2a: 17%; 2b: 6%). PMID:26924506

  15. 从合成三(三苯基膦)氯化铑产生的有机废液中回收铑%Recovery of Rhodium from Organic Waste Liquid Produced from the Synthesis of Chlorotri (triphenylphosphine) rhodium

    Institute of Scientific and Technical Information of China (English)

    刘桂华; 侯文明; 沈善问; 周严; 匡飞平; 冯洋洋; 许明明; 潘再富

    2011-01-01

    针对三(三苯基膦)氯化铑合成过程中产生的含铑有机废液的特点,采用火-湿联用工艺成功回收废液中的铑,回收率约达99%.该工艺的主要工序包括:蒸馏回收乙醇和除去水分、焚烧灰化、氯化、净化、氢还原,最终获得纯铑粉.%A process to recover Rh from organic waste solution by pyrometallurgy - hydrometallurgy method was developed. It consists of; (1) evaporation of ethanol and water from the Rh - containing waste solution yielding a solid mixture; ( 2 ) combustion of triphenylphosphine; ( 3 ) chlorination of the resulting residue to convert rhodium into the solution; (4 ) purification by hydrolysis and ion - exchange; and (5) precipitation by reduction with hydrogen, producing pure rhodium powder. The overall recovery rate was up to 99%.

  16. Reversible de-intercalation and intercalation induced by polymer crystallization and melting in a poly(ethylene oxide)/organoclay nanocomposite.

    Science.gov (United States)

    Sun, Lu; Ertel, Ethan A; Zhu, Lei; Hsiao, Benjamin S; Avila-Orta, Carlos A; Sics, Igors

    2005-06-21

    Semicrystalline polymer/layered silicate nanocomposites were prepared by solution blending of a low molecular weight poly(ethylene oxide) (PEO) with an organically modified montmorillonite, Cloisite 10A (C10A). The intercalation morphology was studied by temperature-dependent synchrotron wide-angle X-ray diffraction (WAXD). Unlike PEO homopolymers, significant secondary crystallization was observed in the PEO/C10A nanocomposites. Reversible de-intercalation and intercalation processes were detected during secondary crystallization and subsequent melting of secondary crystals. On the basis of two-dimensional WAXD results on oriented samples, an interphase layer between the silicate primary particles and PEO lamellar crystals was proposed. Secondary PEO crystallization in the interphase regions was inferred to be the primary driving force for polymer chains to diffuse out of the silicate gallery. This study provided a useful method to investigate polymer diffusion in nanoconfined spaces, which can be controlled by PEO secondary crystallization and melting outside the silicate gallery. PMID:15952806

  17. Site-specific intercalation at the triplex-duplex junction induces a conformational change which is detectable by hypersensitivity to diethylpyrocarbonate.

    OpenAIRE

    Collier, D A; Mergny, J L; Thuong, N T; Helene, C

    1991-01-01

    Using site-specific intercalation directed by intermolecular triplex formation, the conformation of an intercalation site in DNA was examined by footprinting with the purine-specific (A much greater than G) reagent diethylpyrocarbonate. Site specific intercalation was achieved by covalently linking an intercalator to the 5' end of a homopyrimidine oligodeoxynucleotide, which bound to a homopurinehomopyrimidine stretch in a recombinant plasmid via intermolecular triplex formation. This directs...

  18. Clinical Analysis of stereotactic body radiation therapy using extracranial gamma knife for patients with mainly bulky inoperable early stage non-small cell lung carcinoma

    Directory of Open Access Journals (Sweden)

    Tang Hanjun

    2011-07-01

    Full Text Available Abstract Purpose To evaluate the clinical efficacy and toxicity of stereotactic body radiation therapy (SBRT using extracranial gamma knife in patients with mainly bulky inoperable early stage non-small cell lung carcinoma (NSCLC. Materials and methods A total of 43 medically inoperable patients with mainly bulky Stage I/II NSCLC received SBRT using gamma knife were reviewed. The fraction dose and the total dose were determined by the radiation oncologist according to patients' general status, tumor location, tumor size and the relationship between tumor and nearby organ at risk (OAR. The total dose of 34~47.5 Gy was prescribed in 4~12 fractions, 3.5~10 Gy per fraction, one fraction per day or every other day. The therapeutic efficacy and toxicity were evaluated. Results The median follow-up was 22 months (range, 3-102 months. The local tumor response rate was 95.35%, with CR 18.60% (8/43 and PR 76.74% (33/43, respectively. The local control rates at 1, 2, 3, 5 years were 77.54%, 53.02%, 39.77%, and 15.46%, respectively, while the 1- and 2-year local control rates were 75% and 60% for tumor ≤3 cm; 84% and 71% for tumor sized 3~5 cm; 55% and 14.6% for tumor sized 5~7 cm; and 45%, 21% in those with tumor size of >7 cm. The overall survival rate at 1, 2, 3, 5 years were 92.04%, 78.04%, 62.76%, 42.61%, respectively. The toxicity of stereotactic radiation therapy was grade 1-2. Clinical stages were significantly important factor in local control of lung tumors (P = 0.000. Both clinical stages (P = 0.015 and chemotherapy (P = 0.042 were significantly important factors in overall survival of lung tumors. Conclusion SBRT is an effective and safe therapy for medically inoperable patients with early stage NSCLC. Clinical stage was the significant prognostic factors for both local tumor control and overall survival. The toxicity is mild. The overall local control for bulky tumors is poor. Tumor size is a poor prognostic factor, and the patients for

  19. Clinical Analysis of stereotactic body radiation therapy using extracranial gamma knife for patients with mainly bulky inoperable early stage non-small cell lung carcinoma

    International Nuclear Information System (INIS)

    To evaluate the clinical efficacy and toxicity of stereotactic body radiation therapy (SBRT) using extracranial gamma knife in patients with mainly bulky inoperable early stage non-small cell lung carcinoma (NSCLC). A total of 43 medically inoperable patients with mainly bulky Stage I/II NSCLC received SBRT using gamma knife were reviewed. The fraction dose and the total dose were determined by the radiation oncologist according to patients' general status, tumor location, tumor size and the relationship between tumor and nearby organ at risk (OAR). The total dose of 34~47.5 Gy was prescribed in 4~12 fractions, 3.5~10 Gy per fraction, one fraction per day or every other day. The therapeutic efficacy and toxicity were evaluated. The median follow-up was 22 months (range, 3-102 months). The local tumor response rate was 95.35%, with CR 18.60% (8/43) and PR 76.74% (33/43), respectively. The local control rates at 1, 2, 3, 5 years were 77.54%, 53.02%, 39.77%, and 15.46%, respectively, while the 1- and 2-year local control rates were 75% and 60% for tumor ≤3 cm; 84% and 71% for tumor sized 3~5 cm; 55% and 14.6% for tumor sized 5~7 cm; and 45%, 21% in those with tumor size of >7 cm. The overall survival rate at 1, 2, 3, 5 years were 92.04%, 78.04%, 62.76%, 42.61%, respectively. The toxicity of stereotactic radiation therapy was grade 1-2. Clinical stages were significantly important factor in local control of lung tumors (P = 0.000). Both clinical stages (P = 0.015) and chemotherapy (P = 0.042) were significantly important factors in overall survival of lung tumors. SBRT is an effective and safe therapy for medically inoperable patients with early stage NSCLC. Clinical stage was the significant prognostic factors for both local tumor control and overall survival. The toxicity is mild. The overall local control for bulky tumors is poor. Tumor size is a poor prognostic factor, and the patients for adjuvant chemotherapy need to be carefully selected

  20. Group 1 and group 2 metal complexes supported by a bidentate bulky iminopyrrolyl ligand: synthesis, structural diversity, and ε-caprolactone polymerization study.

    Science.gov (United States)

    Kottalanka, Ravi K; Harinath, A; Rej, Supriya; Panda, Tarun K

    2015-12-14

    We report here a series of alkali and alkaline earth metal complexes, each with a bulky iminopyrrolyl ligand [2-(Ph3CN=CH)C4H3NH] (1-H) moiety in their coordination sphere, synthesized using either alkane elimination or silylamine elimination methods or the salt metathesis route. The lithium salt of molecular composition [Li(2-(Ph3CN=CH)C4H3N)(THF)2] (2) was prepared using the alkane elimination method, and the silylamine elimination method was used to synthesize the dimeric sodium and tetra-nuclear potassium salts of composition [(2-(Ph3CN=CH)C4H3N)Na(THF)]2 (3) and [(2-(Ph3CN=CH)C4H3N)K(THF)0.5]4 (4) respectively. The magnesium complex of composition [(THF)2Mg(CH2Ph){2-(Ph3CN=CH)C4H3N}] (5) was synthesized through the alkane elimination method, in which [Mg(CH2Ph)2(OEt2)2] was treated with the bulky iminopyrrole ligand 1-H in 1 : 1 molar ratio, whereas the bis(iminopyrrolyl)magnesium complex [(THF)2Mg{2-(Ph3CN=CH)C4H3N}2] (6) was isolated using the salt metathesis route. The heavier alkaline earth metal complexes of the general formula {(THF)nM(2-(Ph3CN=CH)C4H3N)2} [M = Ca (7), Sr (8), and n = 2; M = Ba (9), n = 3] were prepared in pure form using two synthetic methods: in the first method, the bulky iminopyrrole ligand 1-H was directly treated with the alkaline earth metal precursor [M{N(SiMe3)2}2(THF)n] (where M = Ca, Sr and Ba) in 2 : 1 molar ratio in THF solvent at ambient temperature. The complexes 7-9 were also obtained using the salt metathesis reaction, which involves the treatment of the potassium salt (4) with the corresponding metal diiodides MI2 (M = Ca, Sr and Ba) in 2 : 1 molar ratio in THF solvent. The molecular structures of all the metal complexes (1-H, 2-9) in the solid state were established through single-crystal X-ray diffraction analysis. The complexes 5-9 were tested as catalysts for the ring-opening polymerization of ε-caprolactone. High activity was observed in the heavier alkaline earth metal complexes 7-9, with a very