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Artykuły w czasopismach na temat "Titane atome"
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Dandouras, Iannis, Philippe Garnier, Donald G. Mitchell, Edmond C. Roelof, Pontus C. Brandt, Norbert Krupp i Stamatios M. Krimigis. "Titan's exosphere and its interaction with Saturn's magnetosphere". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 367, nr 1889 (20.11.2008): 743–52. http://dx.doi.org/10.1098/rsta.2008.0249.
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Titan's nitrogen-rich atmosphere is directly bombarded by energetic ions, due to its lack of a significant intrinsic magnetic field. Singly charged energetic ions from Saturn's magnetosphere undergo charge-exchange collisions with neutral atoms in Titan's upper atmosphere, or exosphere, being transformed into energetic neutral atoms (ENAs). The ion and neutral camera, one of the three sensors that comprise the magnetosphere imaging instrument (MIMI) on the Cassini/Huygens mission to Saturn and Titan, images these ENAs like photons, and measures their fluxes and energies. These remote-sensing measurements, combined with the in situ measurements performed in the upper thermosphere and in the exosphere by the ion and neutral mass spectrometer instrument, provide a powerful diagnostic of Titan's exosphere and its interaction with the Kronian magnetosphere. These observations are analysed and some of the exospheric features they reveal are modelled.
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Linnik, О. P., N. P. Smirnova i A. М. Eremenko. "Peculiarities of sol-gel synthesis of co-modified by nitrogen and metal ions (Zn2+, Zr4+, Pt2+) semiconductive TiO2 films". Reports of the National Academy of Sciences of Ukraine, nr 12 (grudzień 2020): 67–74. http://dx.doi.org/10.15407/dopovidi2020.12.067.
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According to the XPS investigation of titania films co-modified by nitro gen and metal ions obtained via sol-gel method, the formation of common bonds between elements occurs due to the presence of metal ions. The mechanism of urea thermolysis is changed as a result of the ability of metal ions to form the complex compounds with urea molecules under the reported synthesis conditions that, in turn, depends on the nature of metal ions, leading to the different chemical compositions of materials’ surface. The XPS data show that nitrogen atoms are surrounded by nonmetal ones on the surface of the films modi fied by Zn2+ or Zr4+ ions. It is suggested that no formation of the complexes between Ті, Zn, or Zr atoms with urea occurs due to its protonation through an oxygen atom leading to the formation of O,N-containing reaction products. In the case of Pt2+ doping, the substitutional nitrogen incorporation in the titania lattice, as well as the formation of N-containing fragments, have been detected. The chemical nature of Pt ions allows them to interact with urea molecules through an N atom of the amino group. As a result, the transformation of urea molecules in the complexes occurs at higher temperatures concurrently with the titania crystallization that is recognized as a catalyst for the intermediates of the urea decomposition leading to the formation of common bonds between N and Ti atoms.
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Jang, Jum Suk, Eun Sun Kim, Hyun Gyu Kim, Sang Min Ji, Youngkwon Kim i Jae Sung Lee. "Nitrogen-doped titanium oxide microrods decorated with titanium oxide nanosheets for visible light photocatalysis". Journal of Materials Research 25, nr 6 (czerwiec 2010): 1096–104. http://dx.doi.org/10.1557/jmr.2010.0133.
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Nitrogen-doped titania with a unique two-level hierarchical structure and visible light photocatalytic activity is reported. Thus, nitrogen-doped titanium oxide microrods decorated with N-doped titanium oxide nanosheets were synthesized by a hydrothermal reaction in NH4OH and postcalcination. During the calcination, the in situ incorporation of nitrogen atoms of ammonium ion into titania lattice was accompanied by the structural evolution from titanate to anatase titania. The morphological and structural evolution was monitored by scanning electron microscopy (SEM), x-ray diffraction (XRD), thermogravimetric analysis/differential thermal analysis (TGA/DTA), Raman, Fourier transform infrared (FTIR), x-ray absorption near edge structure (XANES), x-ray photoelectron spectroscopy (XPS), and adsorption isotherms. The N-doping brought visible light absorption, and the material exhibited high photocatalytic activity in the decomposition of Orange II under visible light irradiation (λ ≥ 400 nm), especially when it was loaded with 1 wt% Pt as a cocatalyst.
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Colombo, Fernando, i Elisa V. Pannunzio Miner. "Synthesis and crystal structure refinement by the Rietveld method of antimony-bearing titanite Ca(Ti0.6Al0.2Sb0.2)OSiO4". Powder Diffraction 24, nr 3 (wrzesień 2009): 221–27. http://dx.doi.org/10.1154/1.3194249.
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A synthetic analogue, Ca(Ti0.6Al0.2Sb0.2)OSiO4, of antimony-bearing titanite of a composition similar to that found at St. Marcel-Praborna (Italy) was synthesized using ceramic methods and the crystal structure was refined using the Rietveld method. Unit-cell dimensions (in Å) are a=7.0184(1), b=8.7097(2), c=6.5586(1), and β=113.700(1)°. The substitution of 40% Ti by (Al+Sb) in octahedra causes a loss of long-range coherency of the off-centered Ti atoms. The space group of Sb-bearing titanite is A2/a, like other cases of M3+-M5+-doped titanites. This study confirms that titanite with up to 0.2 Sb atom per f.u. can exist and that the substitution scheme is 2Ti4+↔Al3++Sb5+.
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Filonenko, О. V., E. M. Demianenko i V. V. Lobanov. "Quantum chemical modeling of orthophosphoric acid adsorption sites on hydrated anatase surface". Surface 12(27) (30.12.2020): 20–35. http://dx.doi.org/10.15407/surface.2020.12.020.
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Quantum chemical modeling of orthophosphoric acid adsorption sites on the hydrated surface of anatase was performed by the method of density functional theory (exchange-correlation functional PBE0, basis set 6-31 G(d,p)). The influence of the aqueous medium was taken into account within the framework of the continual solvent model. The work uses a cluster approach. The anatase surface is simulated by a neutral Ti(OH)4(H2O)2 cluster. The results of analysis of the geometry and energy characteristics of all the calculated complexes show that the highest interaction energy is inherent to the intermolecular complex of orthophosphoric acid and hydrated surface of anatase, where the oxygen atom of the phosphoryl group (О=Р≡) forms a hydrogen bond with a hydrogen atom of the coordinated water molecule of Ti(OH)4(H2O)2 cluster and two hydrogen atoms of the hydroxyl groups of the orthophosphoric acid molecule form two hydrogen bonds with two oxygen atoms of the titanol groups. The formation energy effect of this complex is -134.0 kJ/mol. The formation energy effect of the complex with separated charges by the proton transfer from the molecule H3PO4 to the Ti(OH)4(H2O)2 cluster with the formation of dihydrogen phosphate anion and the protonated form of the titanol group (º) is -131.1 kJ/mol, so indicating less thermodynamic probability of such intermolecular interaction. The smallest thermodynamic probability (-123.9 kJ/mol) of complexation between orthophosphoric acid and hydrated anatase surface where a water molecule moves from the coordination sphere of the titanium atom. The calculation results indicate a possible adsorption of the H3PO4 molecule in an aqueous solution on the hydrated anatase surface. Taking into account the effect of the solvent within the polarization continuum insignificantly changes the adsorption energy, which is -44.5 kJ/mol; for vacuum conditions this value is -49.0 kJ/mol.
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Yang, Fan, Ruizhuang Yang, Lin Yan, Jiankun Wu, Xiaolin Liu, Lirong Yang, Minglong Zhong, Xuan Luo i Lin Zhang. "Enhancement of Titania Photoanode Performance by Sandwiching Copper between Two Titania Layers". Materials 13, nr 19 (28.09.2020): 4326. http://dx.doi.org/10.3390/ma13194326.
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Vacancies in semiconductors can play a versatile role in boosting their photocatalytic activity. In this work, a novel TiO2/Cu/TiO2 sandwich structure is designed and constructed. Abundant vacancies were introduced in TiO2 lattice by Cu reduction under heat treatment. Meanwhile, Cu atom could diffuse into TiO2 to form Cu-doped TiO2. The synergistic effect between oxygen vacancies and Cu atoms achieved about 2.4 times improved photocurrent of TiO2/Cu/TiO2 sandwich structure compared to bare TiO2 thin film. The enhanced photoactivity may be attributed to regulated electron structure of TiO2 by oxygen vacancies and Cu dopant from experimental results and density functional theory calculations. Oxygen vacancies and Cu dopant in TiO2 formed through copper metal reduction can introduce impurity levels and narrow the band gap of TiO2, thus improve the visible light response. More importantly, the Cu2+ and oxygen vacancies in TiO2 lattice can dramatically increase the charge density around conduction band and promote separation of photo-induced charge carriers. Furthermore, the oxygen vacancies on the surface may serve as active site for sufficient chemical reaction. This work presents a novel method to prepare doped metal oxides catalysts with abundant vacancies for improving photocatalytic activity.
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Stoyanov, Emil, Kurt Leinenweber, Thomas L. Groy i Abds-Sami Malik. "Ge0.57Ti0.43O2: a new high-pressure material with rutile-type crystal structure". Acta Crystallographica Section E Crystallographic Communications 74, nr 7 (26.06.2018): 1010–12. http://dx.doi.org/10.1107/s2056989018008988.
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Single crystals of a GeO2–TiO2 solid solution with the corresponding composition Ge0.57Ti0.43O2 (germanium titanium tetraoxide) were obtained by devitrification of germania-titania glass at high pressure and temperature. The new compound crystallizes in the rutile structure type (space group P42/mnm), where Ge and Ti share the same position M (site symmetry m.mm), with occupancy values of 0.57 (3) and 0.43 (3), respectively, and one O-atom position (m.2m). The M site is in a sixfold O-atom coordination and, as in the original TiO2 rutile structure, an elongation of the O—M—O bonds along the c-axis direction of the coordination polyhedron and deviation of the angles from 90° lead to a decrease in the coordination symmetry from octahedral to tetragonal. The Ge and Ti atoms are fully disordered in the structure, which indicates that the rutile structure is surprisingly pliant given the differing sizes of the two cations.
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Enders, M., R. Rudolph i H. Pritzkow. "Synthese und Kristallstruktur von Pentakis(dimethylsulfoxid)- oxo-titan(IV)chlorid / Synthesis and Crystal Structure of Pentakis(dimethylsulfoxide)-oxo-titanium(IV) Chloride". Zeitschrift für Naturforschung B 52, nr 4 (1.04.1997): 496–99. http://dx.doi.org/10.1515/znb-1997-0411.
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Abstract Pentakis(dimethylsulfoxide)-oxo-titanium(IV) chloride is obtained by reaction of titanium tetrachloride with a stoichiometric amount of water in dimethylsulfoxide. A single crystal structure determination (P1̄, a = 9.564(6), b = 10.504(7), c = 12.510(8) Å, α = 70.21(5), β = 83.48(5), γ = 89.82(5)°, V = 1174 Å3, Z = 2) shows a dicationic titanium(IV) complex with five dimethylsulfoxide ligands and one oxygen atom. The two chlorine anions are not bonded to the complex cation. The TiO6-fragment is a distorted octahedron, where five of the six oxygen atoms belong to the coordinated dimethylsulfoxide molecules.
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Liu, Jian, Biqiong Wang, Mohammad N. Banis, Zhiqiang Wang, Ruying Li, Jian Wang, Yongfeng Hu, Tsun-Kong Sham i Xueliang Sun. "Investigation of amorphous to crystalline phase transition of sodium titanate by X-ray absorption spectroscopy and scanning transmission X-ray microscopy". Canadian Journal of Chemistry 95, nr 11 (listopad 2017): 1163–69. http://dx.doi.org/10.1139/cjc-2017-0132.
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Nanostructured sodium titanate has great potential for various applications such as sodium-ion batteries, photocatalysts, and waste treatment. Understanding the phase-transition mechanism in sodium titanate after annealing is fundamentally important to tune the structure, morphology, and property for targeted applications. In this work, we adopted amorphous sodium titanate grown on carbon nanotubes by an atomic layer deposition technique as a reference and used X-ray absorption spectroscopy (XAS) and scanning transmission X-ray microscopy (STXM), as well as a high-temperature in situ X-ray diffraction (XRD) technique, to elucidate the phase-transition mechanism of sodium titanate from amorphous to crystalline upon annealing from 25 °C to 900 °C. XAS and XRD analysis disclosed that anatase TiO2 first formed in the matrix of amorphous sodium titanate at 500 °C and then recrystallized into Na0.23TiO2 at 700 °C and 900 °C. XAS studies also revealed that the Ti atoms in sodium titanate were oxidized during the annealing process and reached an oxidation state about 3.8+ for Na0.23TiO2. The elevated annealing temperature increased the coordination number of Ti atoms and the crystallinity of sodium titanate. STXM chemical map provided spatial information and visualized evidence on the phase transition among amorphous sodium titanate, anatase TiO2, and Na0.23TiO2 in the samples annealed at intermediate temperatures (500 °C and 700 °C). This work provides a comprehensive understanding on the evolution of sodium titanate, in terms of crystal structure, electronic structure, chemical environment, and morphology, under different post annealing conditions.
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Ahmad, Imteyaz, Subramshu Bhattacharya i Horst Hahn. "In-situ nitrogen doping and boron modification of nanocrystalline titania powders by chemical vapour synthesis". Processing and Application of Ceramics 3, nr 3 (2009): 113–17. http://dx.doi.org/10.2298/pac0903113a.
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During the chemical vapour synthesis (CVS) of nanocrystalline titania doping and/or modification can be directly carried out in-situ by using an additional precursor. In this study, nitrogen doped nanocrystalline titania powders and boron modified nanocrystalline titania powders were synthesised by CVS. The resultant powders were characterised by X-ray diffraction (XRD) and UV-vis spectroscopy. In both cases, a red shift in the band gap of titania was seen. Electron paramagnetic resonance spectroscopy (EPR) showed the presence of nitrogen in the titania lattice. Solid state nuclear magnetic resonance (NMR) spectroscopy showed that boron in titania was present in BO4 coordination with the oxygen atoms.
Rozprawy doktorskie na temat "Titane atome"
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Quichaud, Viviane. "Etude des processus elementaires : de synthese de la molecule no, en post-decharge en ecoulement, de collisions titane-gaz rares, titane-molecules, par perturbation laser resolue en temps". Paris 6, 1987. http://www.theses.fr/1987PA066135.
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I. Etude de la preparation des etats excites de no dans un dispositif de post-decharge en ecoulement a partir de n::(2) excite (prepare par transfert d'excitation a partir d'atomes ar metastables dans une decharge basse pression) et de o (obtenu par dissociation de o::(2) dans une decharge de he). Observation d'une emission intense des bandes gamma de no, qui implique un etat a courte duree de vie (b) de n::(2) et le premier etat metastable de o. Ii. Analyse des processus d'extinction et de transfert d'excitation a partir d'etats a courte duree de vie de ti (crees dans un dispositif a cathode creuse) lors de collisions avec des gaz rares (ar, ne, he) et des molecules (n::(2),h::(2)). Ces experiences permettent l'etude de cinetiques de reactions elementaires au sein d'un plasma basse pression ensemence de vapeurs metalliques, a l'aide du dispositif de post-decharge en ecoulement
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Sikora, Thierry. "Etude de l'ordre local et de la structure électronique dans les alliages intermétalliques Ti-Al par spectrométries de structures fines XAS et EELS". Poitiers, 1998. http://www.theses.fr/1998POIT2255.
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La fragilite a temperature ambiante des aluminiures de titane limite pour l'instant leur developpement. Outre leurs microstructures, leur structure electronique semble jouer un role preponderant sur leurs proprietes plastiques (structures de cur des dislocations, energies de faute, relief de peierls). L'ajout en faible quantite d'elements (cr, nb, mn) modifie les liaisons et ameliore dans certains cas la ductilite. Dans ce travail, l'ordre atomique local et la structure electronique du materiau sont etudies par spectrometries de pertes d'energie d'electrons et d'absorption x. Grace a une approche en diffusion multiple, la structure cristallographique locale des composes definis du diagramme ti-al a pu etre resolue sur plusieurs distances inter-atomiques. L'analyse des facteurs debye-waller dans tial montre que les liaisons entre premiers voisins titanes sont plus rigides que celles entre titane et aluminium. Les sites de substitution d'elements d'addition dans les alliages (ti#4#6al#5#4#)#9#7x#3 (x=mn,nb,cr) ont ete determines par alchemi et exafs. Le mn et le nb se substituent au titane alors que le chrome semble occuper les deux sites. On montre egalement qu'il existe une dilatation locale de la matrice autour du solute. L'analyse detaillee des structures fines au seuil par des formalismes de structure de bande et de diffusion multiple a revele que l'approximation a un electron est valide pour la description de ces alliages et que l'utilisation de potentiels non auto-coherents n'est pas critique. Un accord satisfaisant entre experience et theorie obtenu pour les etats inoccupes a permis de confirmer l'existence de fortes hybridations ti-dti-d et ti-dal-sp. Le caractere covalent des liaisons ti-al constitue certainement un parametre important dans le comportement fragile de tial. L'influence des elements d'addition sur la repartition de la densite de charge a montre qu'ils avaient pour effet d'augmenter legerement l'intensite des liaisons dd dans les plans (001).
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Hadjadj, Lakhdar. "Etude à la sonde atomique d'alliages à base titane". Rouen, 1988. http://www.theses.fr/1988ROUES014.
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Etude expérimentale dans les alliages Ti-3Cu, Ti-3Cu-5Al et Ti-10V-2Fe-3Al pour les alliages contenant du cuivre, analyse de la structure des zones de Guinier-Preston, et du rôle de l'aluminium sur la cinétique de précipitation en liaison avec le durcissement du matériau. Etude de l'évolution des phases oméga et alpha au cours des revenus pour l'alliage contenant du fer. Détermination à partir de cette étude, des structures des zones de Guinier-Preston et d'un mode de croissance pour la phase oméga. Analyse des avantages de la sonde atomique dus à sa haute résolution spatiale
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Lumb, Ulrich Verfasser], Rolf [Akademischer Betreuer] Schäfer i M. C. [Akademischer Betreuer] [Böhm. "Entwicklung einer Molekularstrahlapparatur für die hochaufgelöste Mehrphotonen- ionisations-Spektroskopie isolierter Atome u. Moleküle am Beispiel von Titan(II)oxid / Ulrich Lumb ; Rolf Schäfer, Michael Böhm". Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2018. http://d-nb.info/1155510089/34.
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Lumb, Ulrich [Verfasser], Rolf Akademischer Betreuer] Schäfer i M. C. [Akademischer Betreuer] [Böhm. "Entwicklung einer Molekularstrahlapparatur für die hochaufgelöste Mehrphotonen- ionisations-Spektroskopie isolierter Atome u. Moleküle am Beispiel von Titan(II)oxid / Ulrich Lumb ; Rolf Schäfer, Michael Böhm". Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2018. http://d-nb.info/1155510089/34.
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Garnier, Philippe. "Etude de l'interaction entre l'exosphère de Titan et la magnétosphère kronienne, à l'aide des données de l'expérience MIMI (Magnetosphere Imaging Instrument) à bord de Cassini". Phd thesis, Toulouse 3, 2007. http://thesesups.ups-tlse.fr/109/.
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Le plus gros satellite de Saturne, Titan, voit son atmosphère dense en azote bombardée par les ions énergétiques de la magnétosphère, en raison de l'absence de champ magnétique intrinsèque significatif. Des réactions d'échange de charge entre les neutres froids de l'exosphère (plus haute région atmosphérique) et ces ions énergétiques créent alors des atomes énergétiques neutres (ENAs). L'instrument INCA (Ion and Neutral Camera), l'un des trois instruments de l'expérience MIMI (Magnetosphere Imaging Instrument) à bord de la sonde Cassini en orbite autour de Saturne, permet d'imager ces neutres comme des photons et de mesurer leur flux, et fournit ainsi un diagnostic précieux de l'interaction entre Titan et le magnétosphère kronienne. Notre travail de thèse a consisté, en premier lieu, à modéliser l'exosphère de Titan, en considérant à la fois des profils thermiques et non thermiques. Un modèle de calcul de flux d'ENAs a été, en second lieu, développé, comparé aux observations, et enrichi par une étude des processus d'absorption des ENAs. Nous avons ensuite réalisé une analyse statistique des données de l'expérience MIMI durant les traversées d'orbite et survols de Titan. Enfin, une application au satellite de glace Rhéa a permis de fournir des conditions limites pour l'existence de son éventuelle exosphèreThe largest satellite of Saturn, Titan, has a nitrogen-rich atmosphere directly bombarded by magnetospheric energetic ions, due to its lack of a significant intrinsic magnetic field. Charge-exchange collisions between the cold neutrals of its exosphere (the upper part of the atmosphere) and the energetic ions from Saturn's magnetosphere produce then energetic neutral atoms (ENAs). The Ion and Neutral Camera (INCA), one of the three sensors that comprise the Magnetosphere Imaging Instrument (MIMI) on the Cassini spacecraft orbiting around Saturn, images these neutrals like photons, measures their fluxes and provides a powerful diagnostic of the interaction between Titan and the kronian magnetosphere. Our work during this PhD thesis was first to model the Titan exosphere, with both thermal and non thermal profiles. An ENA flux calculation model was then developed, compared to observations and completed with a study of the ENA absorption mechanisms. We have also performed a statistical analysis of the MIMI data during the Titan flybys and orbit crossings. Finally, an application on the icy satellite Rhea allowed to infer upper limits for its eventual exosphere
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Edwards, Samuel Joseph. "Experimental Studies of Ion-Neutral Chemistry Related to the Extraterrestrial Environment". Thesis, University of Canterbury. Chemistry, 2009. http://hdl.handle.net/10092/2224.
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Kinetic data is presented for a variety of ion-neutral reactions which are relevant to the atmosphere of Titan and to the chemistry occurring in interstellar clouds. The data were recorded with a Selected Ion Flow Tube (SIFT) operating at room temperature (294 ± 4 K) and at a pressure of 0.46 Torr. Results of the recent Cassini-Huygens mission to Saturn and Titan have identified several species in the atmosphere of Titan not predicted by pre-Cassini models of the atmosphere. In order to determine the fate of three of these species (methylenimine, propionitrile and cyanodiacetylene) in Titan's ionosphere, their reactivity with the principal ions in Titan's upper ionosphere has been examined. As expected, collision rate proton transfer reactions dominate the chemistry with association channels also observed with many of the hydrocarbon ions. The results of the Cassini mission also identified several individual reactions as being of potential importance to models of Titan's atmosphere and this chemistry has also been examined. The above studies are also relevant to the interstellar medium where each of the neutral reactants have also been detected. The results of some proton transfer equilibrium studies are also presented. The gas phase basicities of propyne and acetylene have been determined to be 681 kJ mol⁻¹ and 617.4 kJ mol⁻¹ respectively. Their relative proton affinities can be estimated from these values. A combined experimental/theoretical study of the proton affinity of cyanodiacetylene (HC₅N) has enabled this value to be estimated at 770 ± 20 kJ mol⁻¹. Details of an attempt to complete the first laboratory measurement of the crucial reaction between H₃⁺ and atomic carbon are presented. The generation of atomic carbon in sufficient quantities for reaction in the SIFT was not possible with the microwave discharge source used. Other generation methods have also been explored with the laser photolysis of carbon suboxide expected to provide a possible solution to the problems encountered. The results of an investigation into the applicability of lithium ions (Li⁺) to SIFT-MS are presented. The lithium ions associated with each of the twenty-one neutral analytes examined to form pseudo-molecular ions. The association reactions were rapid (k ~ 10⁻⁹ cm³ s⁻¹) for large hydrocarbons but were much slower for smaller analytes (k < 10⁻¹¹ cm³ s⁻¹). In order to clarify some unusual experimental observations, the effect of water molecules on the observed chemistry has been examined in detail. The measured chemistry has important consequences for the applicability of Li⁺ to SIFT-MS where the presence and detection of an identifiable ion of the analyte is essential. Details of new SIFT operating software which can be run on a modern computer are given. Mass spectra and kinetic data recorded with the new software are also presented.
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Nguyen, Sorenson Anh Hoang Tu. "Immobilization of Copper Nanoparticles onto Various Supports Applications in Catalysis". BYU ScholarsArchive, 2020. https://scholarsarchive.byu.edu/etd/8892.
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Copper-based materials are one of the most promising catalysts for performing transformations of important organic compounds in both academic and industrial operations. However, it is challenging to consistently synthesize highly active and stable copper species as heterogeneous catalysts due to their relatively high surface energy. As a result, agglomeration usually occurs, which limits the catalytic activities of the copper species. The work presented in this dissertation shows different synthetic strategies for obtaining active and stable copper-based materials by modifying chemical/physical properties of copper nanoparticles (NPs). Emphasis is placed on discussing specific catalytic systems, including carbon-supported catalysts (monometallic and bimetallic copper-based heterogeneous catalysts) and titania-supported catalysts, and their advantages in terms of catalytic performance. In recent years, there has been increasing interest in using metal-organic frameworks (MOFs) as a sacrificial template to obtain carbon-supported NPs via a thermolysis process. The advantages of using MOFs to prepare carbon supported nanomaterials are a fine distribution of active particles on carbon matrix without post-synthesis treatments and corresponding increased catalytic activity and stability in many reaction conditions. To better understand the potential of this synthetic approach, MOF pyrolyzed products have been characterized. Then, they were applied as heterogeneous catalysts for several chemical reactions. In particular, the high energy copper-based MOF, CuNbO-1, was decomposed to obtain an amorphous copper species supported on carbon (a-Cu@C). This catalyst was found to be highly active for reduction, oxidation, and N-arylation reactions without further tuning or optimization. Higher catalyst turnover numbers for each of these transformations were obtained when comparing a-Cu@C activity to that of similar Cu-based materials. To improve catalyst performance, a secondary metal can be introduced to create synergistic effects with the parent copper species. In order to gain insights into the role of the second metal, a well-known Cu-MOF, HKUST-1, was doped with nickel, cobalt, and silver solutions, followed by a decomposition process with 2,4,6-trinitrotoluene (TNT) as additive. This additive was used to enhance the rapid thermolysis of the bimetallic MOFs. In these bimetallic systems, the addition of a second metal was found to help in dispersing both metals over the carbon composite support and in influencing the particle size and oxidation state of the metals. Catalytic performance showed that even <1% of a secondary metal increased the rate for nitrophenol reduction. Optimal catalytic performance was achieved using a Ni-CuO@C bimetallic catalyst. Another synthetic strategy for Cu-catalyst preparation involves using the deposition-precipitation method, in which a copper catalyst anchored on a titania support was synthesized at low weight % in order to obtain a single atom catalyst (1-Cu/TiO2). The higher copper loading catalyst, 5-Cu/TiO2, was synthesized as a benchmark catalyst for comparison. The copper structure in the synthesized catalysts was investigated by powder X-ray diffraction (PXRD), Raman, scanning transmission electron microscopy-energy dispersive X-ray spectroscopy (STEM-EDX), X-ray photoelectron spectroscopy (XPS), N2 physisorption and inductively coupled plasma mass spectrometry (ICP-MS) in order to characterize physical and chemical properties. STEM-EDX observations showed single atom copper species less than 0.75 nm in size, as well as nanoparticles with an average diameter of ~1.31 nm. This catalyst was highly active in the reduction of nitro-aromatic compounds with NaBH4 at room temperature. The small to atomic level sizes of the Cu species and multiple oxidation states of Ti species were found to play a crucial role in the catalytic activity.
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Huguet, Anne. "Etude à la sonde atomique et par microscopie ionique à champ de la composition des phases alpha deux et gamma dans des alliages à base TiAl". Rouen, 1994. http://www.theses.fr/1994ROUES072.
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La structure fine d'alliages intermétalliques à base TiAl monophasés gamma et biphasés alpha deux et gamma, matériaux potentiels pour des applications structurales à haute température dans le domaine de l'aérospatial, est étudiée par microanalyse au moyen de la sonde atomique et du microscope ionique. La première partie de cette étude traite de la distribution de l'oxygène, du carbone et de l'azote, impuretés interstitielles d'élaboration, dans des alliages monophasés gamma et biphasés alpha deux et gamma. A partir des résultats expérimentaux, une analyse critique du rôle des éléments interstitiels vis-à-vis de la ductilité à basse température de ces matériaux est donnée. L'étude de l'évolution thermique de la structure lamellaire alpha deux et gamma de matériaux à base TiAl biphasés constitue la seconde partie de ce mémoire. L'hypothèse d'une compétition entre les mécanismes de coalescence discontinue et continue des lamelles y est proposée et discutée
10
Lumb, Ulrich. "Entwicklung einer Molekularstrahlapparatur für die hochaufgelöste Mehrphotonen- ionisations-Spektroskopie isolierter Atome u. Moleküle am Beispiel von Titan(II)oxid". Phd thesis, 2018. https://tuprints.ulb.tu-darmstadt.de/7275/7/Dissertation_Lumb.pdf.
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In dieser Arbeit wurde ein Lasersystem und eine gepulste Molekularstrahlapparatur aufgebaut, welche zusammen die
Beobachtung von elektronischen Übergängen in isolierten Atomen und Molekülen ermöglichen.
Die optische Auflösung des Lasersystems kann in einem Bereich zwischen 0,1cm
−1
und 0,004cm
−1
an die spektro-
skopischen Anforderungen eines zur Beobachtung ausgewählten Überganges angepasst werden. Je nach benötigter
spektraler Auflösung können so die Energieniveaus der beobachteten Atome und Moleküle bis zur Rotationsfeinstruktur
von schweren Elementdimeren ausgemessen werden. Gleichzeitig kann die relative Besetzung der Energieniveaus im
Molekularstrahl bestimmt werden.
Die Detektion der optischen Übergänge folgt dabei dem Grundschema der Ionisationsspektroskopie, das heißt neutrale
Atome oder Moleküle werden in der Molekularstrahlapparatur mittels mehrstufiger optischer Anregung ionisiert und mit
einem Flugzeitmassenspektrometer semi-quantitativ nachgewiesen. Der kollineare Aufbau des Flugzeitspektrometers
erwies sich gegenüber einem orthogonalen Aufbau in zweifacher Hinsicht als Vorteilhaft, da so die Ionenausbeute und
die Massenauflösung deutlich gesteigert werden konnte.
Das Lasersystem stellt zwei verschiedene Ionisationswellenlängen zu Verfügung, von denen eine als Maß für die relative
Gesamtzahl an Clustern im Molekularstrahl verwendet werden kann. Durch die mitunter starken Zusammensetzungs-
änderungen zwischen einzelnen Molekularstrahlpulsen, ist die zweite Wellenlänge allerdings nicht immer ausreichend
für eine Referenzbildung zur Erkennung von optischen Übergängen.
Die gepulste Molekularstrahlapparatur sorgt zum einen für eine deutliche Vereinfachung der zu erwartenden Spektren,
da die Besetzung der Energieniveaus der Atome und Moleküle bei der adiabatischen Expansion sich zu energetisch
niedrigeren Niveaus verschiebt. Andererseits wird durch die Einschränkung der Bewegungsrichtung der Atome und
Moleküle eine Verkleinerung der Dopplerbreite der Absorptionslinien bewirkt.
Die Funktionstüchtigkeit der Apparatur wurde am Titan(II)oxid, welches eines der kompliziertesten Absorptionsspek-
tren zweiatomiger Moleküle aufweist, unter Beweis gestellt. Die Daten der aufgenommenen Spektren erlauben es, die
relativen Besetzungszahlverhältnisse der spin-bahn-aufgespaltenen Zustände zu bestimmen und die Abkühlung der
elektronischen Freiheitsgrade des TiO bei der Bildung des Molekularstrahls mit den Experimenten anderer Autoren
zu vergleichen. Durch Verbesserung des Auflösungsvermögens kann die Verteilung der Besetzungsverhältnisse der
Rotationsenergieniveaus bei TiO beobachtet werden, welche Hinweise auf einen komplizierten Abkühlmechanismus
während der Überschallexpansion des Molekularstrahls gibt.
Die Auswertung der experimentellen Daten und das theoretische Rüstzeug zur Datenauswertung wird ausführlich
beschrieben.
Książki na temat "Titane atome"
1
Smyth, William H. Studies of the gas tori of Titan and Triton. Cambridge, MA: Atmospheric and Environmental Research, Inc., 1995.
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2
Smyth, William H. Studies of the gas tori of Titan and Triton: Final report for the period, January 24, 1994 to July 23, 1997. [Washington, DC: National Aeronautics and Space Administration, 1997.
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4
Glennan, Stuart. Postscript. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198779711.003.0009.
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As I have worked on this book, I have often been struck by the audacity of its title. The phrase “the New Mechanical Philosophy” was not my own, but still, to appropriate the venerable tradition of mechanical philosophy, to call it new, and to add a definite article to boot—maybe that’s just too much. Nonetheless I have stuck with the title, and the project, because I think it reflects both the continuity with the history of science and its philosophy, and a sea change in philosophical thinking in the new century. Mechanical philosophy is as old as Democritus; it was a central theme in the scientific revolution; it has helped drive research and debates on the nature of life and the nature of mind. But the New Mechanical Philosophy is new in large part because it tracks changes in the way science is done. Over recent decades, the sciences have developed increasing, if still rudimentary, capacities to analyze complex and heterogeneous systems—cells, brains, ecosystems, economies, and so on. Whereas in earlier epochs many of the greatest scientific achievements have been to understand the basic building blocks—the laws of electricity and magnetism or the structure of the hydrogen atom—scientists are now able to greater and greater extents understand how these things are put together to make the universe we know. Mechanical philosophy is always about understanding how things are put together, so it is a philosophy for this time....
Części książek na temat "Titane atome"
1
Futaana, Yoshifumi, Jean-Yves Chaufray, H. Todd Smith, Philippe Garnier, Herbert Lichtenegger, Magda Delva, Hannes Gröller i Alessandro Mura. "Exospheres and Energetic Neutral Atoms of Mars, Venus and Titan". W Space Sciences Series of ISSI, 213–66. New York, NY: Springer US, 2011. http://dx.doi.org/10.1007/978-1-4614-3290-6_7.
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2
Rosi, Marzio, Stefano Falcinelli, Nadia Balucani, Piergiorgio Casavecchia, Francesca Leonori i Dimitris Skouteris. "Theoretical Study of Reactions Relevant for Atmospheric Models of Titan: Interaction of Excited Nitrogen Atoms with Small Hydrocarbons". W Computational Science and Its Applications – ICCSA 2012, 331–44. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-31125-3_26.
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3
Meirelles Malusá Gonçalves, Josiane, Mary Carmem Fróes Ribeiro i Andresa Aparecida Berretta. "Acupuncture, Yoga, Homeopathy, and Apitherapy under the Vibrational Point of View". W Alternative Medicine [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.94997.
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Albert Einstein was one of the greatest physicists in recent history and his contributions changed the paradigm of science in the 20th century. From this, it was proposed the understanding that all matter is energy, and we can assume the understanding that the human body is a dynamic energy system. Energy and matter are two different manifestations of the same universal substance from which we are all formed, atoms. It is known that the movement between the constituent parts of the atom (electrons, neutrons, protons and smaller particles) and the forces that connect them, generates energy. Since the atoms are in constant movement, what can be measured is vibration. Therefore, in this chapter, we propose to present some millenary therapies like acupuncture, yoga, apitherapy and, more recently, Homeopathy, under the point of view of vibrational integrative therapies, exploring the hypothesis that through these therapies we can adapt the waves generated in the bodies to transform them into personalized therapeutic agents.
4
Takiya, Toshio, i Naoaki Fukuda. "Nanoparticle Formation and Deposition by Pulsed Laser Ablation". W Laser Ablation [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.95299.
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Pulsed Laser Ablation (PLA) in background gas is a good technique to acquire specific nanoparticles under strong non-equilibrium states. Here, after a history of PLA is mentioned, the application of nanoparticles and its deposition films to the several fields will be described. On the target surface heated with PLA, a Knudsen layer is formed around the adjacent region of the surface, and high-pressure and high-temperature vapor atoms are generated. The plume formed by evaporated atoms blasts off with very high-speed and expands rapidly with a shock wave. A supercooling phenomenon occurs during this process, and number of nucleus of nanoparticle forms in vapor-phase. The nuclei grow by the condensation of vapor atoms and deposit on a substrate as nanoparticle film. If the radius of nanoparticle is uniformized, a self-ordering formation can be shown as a result of interactive process between each nanoparticle of the same size on the substrate. In this chapter, the related technology to realize a series of these processes will be expounded.
5
H. Al-Tamimi, Basma, i Saad B.H. Farid. "Fullerenes and Nanodiamonds for Medical Drug Delivery". W Nanocrystals [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.97867.
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Carbon is a chemical element has the ability of forming long carbonic chain. Due to its special electronic structure, each carbon atom can be linked with another carbon atom or with another element via single, double or triple covalent bonds. The special electronic structure of carbon atom affecting on its properties also affecting on its ability of existing in different forms called allotropes. During few last decades, new carbon-based nanomaterials have been described including fullerene, carbon nanotube, graphene and nanodiamond. These new allotropes attracted the interest of science and industry and became as a new and important class of materials due to its outstanding features which candidate for numerous applications. In parallel with new developments in nanomedicine especially in drug delivery field, the targeted delivery systems became an important to overcome the limitations of the old fashion systems. So, it become very important to translate this idea into reality. Fullerene and nanodiamond have a unique combination of structure, morphology and biological properties that make them as a powerful tools for targeted delivery system. So, this chapter will focus on two major aspects: synthesis routes of fullerenes and nanodiamonds, and their role in nanomedicine as drug delivery systems.
6
Coppens, Philip. "Electron Density Studies of Molecular Crystals". W X-Ray Charge Densities and Chemical Bonding. Oxford University Press, 1997. http://dx.doi.org/10.1093/oso/9780195098235.003.0014.
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Small molecules consisting of light-, few-electron atoms were the first species beyond atoms to yield to quantum-mechanical methods. Similarly, crystals of small light-atom molecules have served as most useful test cases of charge density mapping. The small number of core electrons in first-row atoms enhances the relative contribution of valence electron scattering to the diffraction pattern. Early studies, done just after automated diffractometers became widely available, were concerned with molecular crystals such as uracil (Stewart and Jensen 1967), s-triazine (Coppens 1967), oxalic acid dihydrate (Coppens et al. 1969), decaborane (Dietrich and Scheringer 1978), fumaramic acid (Hirshfeld 1971), glycine (Almlof et al. 1973), and tetraphenylbutatriene (Berkovitch-Yellin and Leiserowitz 1976). While thermal motion is often pronounced in molecular crystals, advances in low-temperature data collection have done much to alleviate this disadvantage. In recent years, subliquid-nitrogen cooling techniques have been increasingly applied. Among the most interesting aspects of molecular crystals are the influence of intermolecular interactions on the electronic structure. Physically meaningful Coulombic parameters pertinent to a molecule in a condensed environment can be obtained from the diffraction analysis, and can be used in the modeling of macromolecules. The enhancement of the electrostatic moments relative to those of the isolated species has been noted in chapter 7. But, beyond these considerations, molecular crystals are important in their own right. For example, crystals of aromatic molecules substituted with π-electron donor and acceptor groups are among the most strongly nonlinear optical solids known, considerably exceeding the nonlinearity of inorganic crystals such as potassium titanyl phosphate (KTP); while mixed-valence organic components of low-dimensional solids can become superconducting at low temperatures. The relation between such properties of molecular crystals and their charge distribution provides a continuing impetus for further study. The suitability of light-atom crystals for charge density analysis can be understood in terms of the relative importance of core electron scattering. As the perturbation of the core electrons by the chemical environment is beyond the reach of practically all experimental studies, the frozen-core approximation is routinely used. It assumes the intensity of the core electron scattering to be invariable, while the valence scattering is affected by the chemical environment, as discussed in chapter 3.
7
Navarro-Santos, Pedro, Rafael Herrera-Bucio, Judit Aviña-Verduzco i Jose Luis Rivera. "Calculation of the Electronic Properties and Reactivity of Nanoribbons". W Nanofibers [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.94541.
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It has been demonstrated that matter at low dimensionality exhibits novel properties, which could be used in promising applications. An effort to understand their behavior is being through the application of computational methods providing strategies to study structures, which present greater experimental challenges. It is proven that thin and narrow carbon-based nanostructures, such as, nanoribbons show promising tunable electronic properties, particularly when they are substitutionally functionalized. This chapter is proposed as a guidance to help the readers to apply conceptual density functional theory to calculate helpful intrinsic properties, e. g., energetic, electronic and reactivity of one-dimension nanomaterial’s, such as, carbon nanoribbons. As a case of study, it is discussed the effect of boron atoms on the properties of pristine carbon nanoribbons concerning the main aspect and considerations must take into account in their computational calculations.
8
Carolina Cardoso-Teixeira, Ana, Klausen Oliveira-Abreu, Levy Gabriel de Freitas Brito, Andrelina Noronha Coelho-de-Souza i José Henrique Leal-Cardoso. "Effects of Terpenes and Terpenoids of Natural Occurrence in Essential Oils on Vascular Smooth Muscle and on Systemic Blood Pressure: Pharmacological Studies and Perspective of Therapeutic Use". W Terpenes and Terpenoids [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.94194.
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Terpenes are a class of chemical compounds with carbon and hydrogen atoms in their structure. They can be classified into several classes according to the quantity of isoprene units present in its structure. Terpenes can have their structure modified by the addition of various chemical radicals. When these molecules are modified by the addition of atoms other than carbon and hydrogen, they become terpenoids. Terpenes and terpenoids come from the secondary metabolism of several plants. They can be found in the leaves, fruits, stem, flowers, and roots. The concentration of terpenes and terpenoids in these organs can vary according to several factors such as the season, collection method, and time of the day. Several biological activities and physiological actions are attributed to terpenes and terpenoids. Studies in the literature demonstrate that these molecules have antioxidant, anticarcinogenic, anti-inflammatory, antinociceptive, antispasmodic, and antidiabetogenic activities. Additionally, repellent and gastroprotective activity is reported. Among the most prominent activities of monoterpenes and monoterpenoids are those on the cardiovascular system. Reports on literature reveal the potential effect of monoterpenes and monoterpenoids on systemic blood pressure. Studies show that these substances have a hypotensive and bradycardic effect. In addition, the inotropic activity, both positive and negative, of these compounds has been reported. Studies also have shown that some monoterpenes and monoterpenoids also have a vasorelaxing activity on several vascular beds. These effects are attributed, in many cases to the blocking of ion channels, such as voltage-gated calcium channels. It can also be observed that monoterpenes and monoterpenoids can have their effects modulated by the action of the vascular endothelium. In addition, it has been shown that the molecular structure and the presence of chemical groups influence the potency and efficacy of these compounds on vascular beds. Here, the effect of several monoterpenes and monoterpenoids on systemic blood pressure and vascular smooth muscle will be reported.
9
Chand Verma, Kuldeep. "Diluted Magnetic Semiconductor ZnO: Magnetic Ordering with Transition Metal and Rare Earth Ions". W Magnetic Materials [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.90369.
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For advancement in future spintronics, the diluted magnetic semiconductors (DMSs) might be understood for their origin of ferromagnetic aptness. It not much clear to the ferromagnetism in DMS, that is intrinsic or via dopant clustering formation. For this, we have included a review study for the doping of transition metal and rare earth ions in ZnO. It is realized that the antiferromagnetic ordering is found in doped ZnO to achieve high-TC ferromagnetism. X-ray diffraction and Raman spectra techniques have been used to detect the wurtzite ZnO structure and lattice defects. Since ZnO has different types of morphology formation that is generally dependent on synthesis conditions and dopant level. The band gap energy of ZnO and lattice defect formation are shown by photoluminescence technique. The room temperature ferromagnetism is described with bound magnetic polaron (BMP) model in which oxygen vacancies play a major role. However, the temperature-dependent conditions are responsible for ferromagnetic ordering. The first principle calculation is used for dopant ions in ZnO for their replacement of Zn2+ atoms in the wurtzite structure as well as magnetic contribution.
10
Gautam, Budhayash. "Energy Minimization". W Homology Molecular Modeling - Perspectives and Applications [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.94809.
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The energetic state of a protein is one of the most important representative parameters of its stability. The energy of a protein can be defined as a function of its atomic coordinates. This energy function consists of several components: 1. Bond energy and angle energy, representative of the covalent bonds, bond angles. 2. Dihedral energy, due to the dihedral angles. 3. A van der Waals term (also called Leonard-Jones potential) to ensure that atoms do not have steric clashes. 4. Electrostatic energy accounting for the Coulomb’s Law m protein structure, i.e. the long-range forces between charged and partially charged atoms. All these quantitative terms have been parameterized and are collectively referred to as the ‘force-field’, for e.g. CHARMM, AMBER, AMBERJOPLS and GROMOS. The goal of energy Minimization is to find a set of coordinates representing the minimum energy conformation for the given structure. Various algorithms have been formulated by varying the use of derivatives. Three common algorithms used for this optimization are steepest descent, conjugate gradient and Newton–Raphson. Although energy Minimization is a tool to achieve the nearest local minima, it is also an indispensable tool in correcting structural anomalies, viz. bad stereo-chemistry and short contacts. An efficient optimization protocol could be devised from these methods in conjunction with a larger space exploration algorithm, e.g. molecular dynamics.
Streszczenia konferencji na temat "Titane atome"
1
Zhu, Lin, Jeong Ho You i Jinghong Chen. "First-Principles Calculations and Molecular Dynamics Simulations on Effect of Hydrogen Impurity in Lead Titanate Films". W ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-67796.
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Properties of ferroelectric films are highly influenced by inevitable defects, such as hydrogen impurity. This study is focused on theoretical and numerical studies to probe effects of hydrogen contamination on ferroelectric stability in PbTiO3 (PTO) films using the first-principles effective Hamiltonian. First-principles calculations are performed to determine the possible position, formation energy, and mobility of hydrogen impurity atom, and the calculated results are used as inputs to molecular dynamics (MD) simulations in a large system. The hydrogen atom is able to move along the polarization with small energy barriers. The energy difference between a hydrogen contaminated PTO and a pure PTO is considered as an energy penalty term induced by hydrogen contamination and has been added to the effective Hamiltonian. Then, the MD effective Hamiltonian with the energy penalty is employed in MD simulations to investigate the effects of hydrogen contamination on the ferroelectric responses of PTO films with various thicknesses and temperatures. The hysteresis loops are presented and analyzed for PTO films with various concentrations of hydrogen impurities and thicknesses. Hydrogen contamination reduces the remnant polarization, especially for thin films. As the concentration of hydrogen impurities increases, the critical thickness increases. By analyzing the vertical cross section snapshots, it has been found that the hydrogen impurity atoms near interfaces affect the polarization throughout the entire PTO films.
2
Mulliner, K., i Zin Lin. "Interactive journal-title searching via a network of concept-atoms". W the 1985 ACM annual conference, chair Yin Wei. New York, New York, USA: ACM Press, 1985. http://dx.doi.org/10.1145/320435.320567.
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