918 resultados para Siglos IV-V


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A novel compound [Cu(en)(2)](4)[(SiMo8V4O40)-O-v(V-IV O)(2)] [MoO4](2) . 5H(2)O has been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction. Black crystals crystallize in the tetragonal. system, space group 14/m, a = b = 14.019(2) Angstrom, c = 20.341(4) Angstrom, V = 3997.9(11) Angstrom(3), Z = 2, lambda(MoKalpha) = 0.71073 Angstrom (R(F) = 0.0443 for 1819 reflections). Data were collected on a Siemens P4 four-circle diffractometer at 293 K in the range of 1.76 < theta < 24.98degrees using the omega-scan technique. The structure was solved by the direct method and refined by the full-matrix least squares on F-2 method using the SHELXL-97 software. X-ray crystallographic study showed that the title compound contained a bicapped alpha-Keggin fragment [SiMo8 (V4O40)-O-v((VO)-O-IV)(2)](4-) polyoxoanion.

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The title compound, [NH3CH2CH2CH2NH2][NH3CH2CH2CH2NH3](2)[As-2(III) As-v Mo-8 V-4(IV) O-40] (.) 5H(2)O, was hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction. Crystal data: monoclinic, C2/c, a = 45.375(9) Angstrom, b = 11.774(2) Angstrom, c = 23.438(5) Angstrom, beta = 96.62(3)degrees. X-ray crystallographic study showed that the crystal structure was constructed by bi-capped alpha -Keggin fragments [(As2AsMo8V4O40)-As-III-Mo-v-O-IV](5-) polyoxoanion. (C) 2001 Elsevier Science B.V. All rights reserved.

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Based on the complex crystal chemical bond theory, the formula of Liu and Cohen's, which is only suitable for one type of bond, has been extended to calculate the bulk modulus of ternary chalcopyrite A(I)B(III)C(2)(VI) and A(II)B(IV)C(2)(V) which contains two types of bonds. The calculated results are in fair agreement with the previous theoretical values reported and experimental values. (C) 1998 Elsevier Science Ltd. All rights reserved.

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[NH4](4)H[(PMo8V4V2O42)-V-IV-O-V] . 24H(2)O has been hydrothermally synthesized from ammonium vanadate and sodium molybdate in aqueous solution by adding phosphorous acid, and its structure determined by single crystal X-ray analysis. The heteropoly molybdovanadophosphate anion is a bicapped 'pseudo-Keggin' polyanion, two vanadium atoms are distributed at two 'capping' metal atom positions and other four vanadium atoms randomly distributed at eight metal atom positions. (C) 1998 Elsevier Science Ltd. All rights reserved.

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V(IV) and V(V) containing mixed-valence heteropolytungstogermanates have been prepared by controlled potential reduction of corresponding GeW9V3O407-, their electronic spectra have been recorded. The ESR spectra of one-electron-reduced anions in solution at 340K consist of more than 40 equally spaced lines, showing that the three VO6 octahedra in both alpha- and beta-forms are corner-shaped and one of the bridging oxygen atoms is protonated at pH 4.7.

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¿A qué recuerda ese residuo de infelicidad (imperfección, inexactitud) que jamás llega a compensar la piedra más preciosa (fórmula, igualdad) y cuyo conocimiento determina el número exacto de quilates (perfección, igualdad) a la que debe aproximarse el diamante final (sucesión, serie, límite)? Sólo conociendo bien ese residuo evitaremos errores de cálculo, errores en la igualdad.

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We report calculations for energy levels, radiative rates and electron impact excitation rates for transitions in He-like Li II, Be III, B IV and C V. grasp (general-purpose relativistic atomic structure package) is adopted for calculating energy levels and radiative rates. For determining the collision strengths and subsequently the excitation rates, the Dirac atomic R-matrix code (darc) is used. Oscillator strengths, radiative rates and line strengths are reported for all E1, E2, M1 and M2 transitions among the lowest 49 levels of each ion. Collision strengths have been averaged over a Maxwellian velocity distribution and the effective collision strengths so obtained are reported over a wide temperature range up to 10(6) K. Comparisons have been made with similar data obtained from the flexible atomic code (FAC) to highlight the importance of resonances, included in calculations from darc, in the determination of effective collision strengths. Discrepancies between the collision strengths from darc and fac, particularly for weak transitions and at low energies, have also been discussed. Additionally, lifetimes are also listed for all calculated levels of the above four ions.

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Energies and lifetimes are reported for the lowest 375 levels of five Br-like ions, namely SrIV, YV, ZrVI, NbVII, and MoVIII, mostly belonging to the 4s<sup>2</sup>4p<sup>5</sup>, 4s<sup>2</sup>4p<sup>4</sup>4ℓ, 4s4p<sup>6</sup>, 4s<sup>2</sup>4p<sup>4</sup>5ℓ, 4s<sup>2</sup>4p<sup>3</sup>4d<sup>2</sup>, 4s4p<sup>5</sup>4ℓ, and 4s4p<sup>5</sup>5ℓ configurations. Extensive configuration interaction has been included and the general-purpose relativistic atomic structure package (grasp) has been adopted for the calculations. Additionally, radiative rates are listed among these levels for all E1, E2, M1, and M2 transitions. From a comparison with the measurements, the majority of our energy levels are assessed to be accurate to better than 2%, although discrepancies between theory and experiment for a few are up to 6%. An accuracy assessment of the calculated radiative rates (and lifetimes) is more difficult, because no prior results exist for these ions.

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The main populating and depopulating mechanisms of the excited energy levels of ions in plasmas with densities <1023-1024 m-3 are electron collisional excitation from the ion's ground state and radiative decay, respectively, with the majority of the electron population being in the ground state of the ionization stage. Electron collisional ionization is predominately expected to take place from one ground state to that of the next higher ionization stage. However, the question arises as to whether, in some cases, ionization can also affect the excited level populations. This would apply particularly to those cases involving transient events such as impurity influxes in a laboratory plasma. An analysis of the importance of ionization in populating the excited levels of ions in plasmas typical of those found in the edge of tokamaks is undertaken for the C IV and C V ionization stages. The emphasis is on those energy levels giving rise to transitions of most use for diagnostic purposes (n ≤ 5). Carbon is chosen since it is an important contaminant of JET plasmas; it was the dominant low Z impurity before the installation of the ITER-like wall and is still present in the plasma after its installation. Direct electron collisional ionization both from and to excited levels is considered. Distorted-wave flexible atomic code calculations are performed to generate the required ionization cross sections, due to a lack of atomic data in the literature. Employing these data, ionization from excited level populations is not found to be significant in comparison with radiative decay. However, for some energy levels, ionization terminating in the excited level has an effect in the steady-state of the order of the measurement errors (±10%). During transient events, ionization to excited levels will be of more importance and must be taken into account in the calculation of excited level populations. More accurate atomic data, including possible resonance contributions to the cross sections, would tend to increase further the importance of these effects. 

1.° Tractatus pacis inter Ludovicum IX. Regem Francorum, et Henricum III. Regem Angliae : anno 1259. — 2.° Tractatus pacis inter Philippum III. Regem Francorum, et Edwardum I. Regem Angliae : anno 1279. — 3.° Tractatus pacis inter eosdem Reges : anno 1286. — 4.° Quarta et ultima pax facta inter Reges : anno 1303. translata de romancio in latinum, de verbo ad verbum. — 5.° Alia concordantia, seu compositio vel pax inter Reges : anno 1303. — 6.° Pronunciatio Bonifacii, Papae, super pacibus : anno pontificatus quarto. — 7.° De remediis Aquitanorum adversùs vexationem curiae Regis Franciae. — 8.° Copia arresti contra Arnaldum de Romynhano, dati anno 1312. — 9.° Variae litterae Philippi Pulchri et Ludovici X. de rebus Anglicis. — 10.° Bulla Clementis, Papae V. approbans donationem Motae et domorum de Pessaco, factam ecclesiae Burdegalensi à nobili viro Gaillardo de Guto, germano suo, anno primo pontificatus. — 11.° Traitté de paix conclu entre les Rois Philippe et Edouard ; sans date. — 12.° Lettres de Charles IV. Roy de France et de Navarre, touchant les excès commis au lieu de Saint-Sacerdos par le Senechal de Gascogne : l'an 1324. — 13.° Traitté entre la France et l'Angleterre : en la même année. — 14.° Judicium latum apud Oleronem, anno 1287. per D. Norwicensem Episcopum, contra D. Joannem de Greilliaco, dudum Senescallum Vasconiae. — 15.° Tractatus matrimonii inter Alienoram filiam Edwardi Regis Angliae, et Alphonsum filium majorem Petri Regis Aragonum. — 16.° Litterae Petri, Regis Aragonum, de matrimonio filii sui Alphonsi cum Alienora, filia primogenita Regis Edwardi. — 17.° Joannis XXII. bulla contra Michaëlem de Cesena, Ministrum generalem ordinis Minorum : VIII. idus Junii, pontificatus anno XII. — 18.° Edwardi, Regis Anglorum, constitutiones variae ad Aquitaniam spectantes et ad Angliam. — 19.° Traitté de paix entre les Rois de France et d'Angleterre, fait en l'an 1325. — 20.° Litterae Agennensium ad Carolum IV. Regem Franciae, pro Rege Angliae, nominatim de facto Sancti-Sacerdotis, scriptae anno 1324. — 21.° Tractatus matrimonii inter Alphonsum, Regem Castellae et Legionis, et Alienoram, filiam Edwardi Regis Angliae ; item alius inter Edwardum, Regis Angliae primogenitum, et Alienoram sororem Regis Castellae : anno 1325. — 22.° Instructions données par le Roy d'Angleterre à ses Ambassadeurs allans en Espagne pour le fait dudit mariage. — 23.° Abusiones quae exercentur in regno Angliae circa beneficia ecclesiastica ; et remedia sine quibus nunquam cessare creduntur. — 24.° Clementis V. bulla de saecularisatione monasterii de sancto Aemiliano, in dioecesi Burdigalensi ; data anno pontificatus quinto. — 25.° Litterae Edwardi II. Regis Angliae, de servanda pace facta cum Carolo IV. Rege Franciae. — 26.° Ejusdem litterae quibus Edmundum, Comitem Cantiae, fratrem suum, constituit Capitaneum in Ducatu Aquitaniae. — 27.° Lettres de Charles IV. Roy de France, contre le Roy d'Angleterre, qui refusoit de luy faire les foy et hommage pour la Duché d'Aquitaine : de l'année 1324. — 28.° Litterae ejusdem Caroli IV. Regis Francorum, de eadem re ; quibus Carolo, Comiti Valesiae, patruo suo, dat potestatem puniendi rebelles Aquitaniae ; datae anno 1324. — 29.° Litterae ejusdem de salvagardia Guillelmi Galteri, Clerici, datae anno 1323. — 30.° Ejusdem litterae pro Margareta de Guouda, tutrice Pontii domini de Castellione, filii sui, datae anno 1323. — 31.° Ejusdem litterae pro Comitissa Fuxi et Vicecomitissa Bearni et Marciani, tutrice Gastonis filii sui ; datae anno 1322. — 32.° Litterae Antonini Pessaigne, Senescalli Ducatus Aquitaniae, quibus Ostencium Jordani, Clericum ac Jurisperitum, constituit suum et Regis Angliae Procuratorem ; datae anno 1318. — 33.° Litterae Almarici domini de Credonio, Senescalli Ducatus Aquitaniae, quibus Roberto de la Vertadausa, Anglico, decem libras Turonensium parvorum singulis annis solvendas concedit vice et nomine Regis Angliae ; datae anno 1322. — 34.° Divers actes entre les Rois de France et d'Angleterre, pour assurer la paix ; faits depuis l'an 1259. jusques en 1323. — 35.° Acta processus habiti in curia Romana inter capitulum ecclesiae Coventrensis et capitulum ecclesiae Lichefeldiensis de electione Episcopi, tempore Joannis XXII. — 36.° Traitté d'alliance et de confederation entre la France et l'Ecosse contre l'Angleterre ; fait en 1325. — 37.° Articuli exhibiti à Procuratore ecclesiae Lichfeldensis. — 38.° Articuli exhibiti à Procuratore ecclesiae Coventrensis. — 39.° Joannis XXII. bulla de unione Episcopatuum Corkagiensis et Clonensis, data Avenione anno pontificatus XI. — 40.° Acta processus apud eumdem Papam agitati super praebenda sancti Stephani in ecclesia Beverlacensi.

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Colbertinus