Search results for "NICKEL"
showing 10 items of 1087 documents
Valutazione in vitro dell’affaticamento di strumenti rotanti in nichel-titanio
2012
Riassunto Obiettivo L’obiettivo di questo lavoro e quello di valutare, in vitro, la fatica ciclica di ProFile, K3 e Twisted File, strumenti rotanti in nichel-titanio, in canali radicolari simulati aventi angoli di curvatura di 45°, 60° e 90°. Materiali e metodi Per effettuare questo studio sono stati utilizzati: 18 file 25/.06 ProFile; 18 file 25/.06 K3; 18 file 25/.06 Twisted File. La resistenza a fatica ciclica degli strumenti rotanti Ni-Ti e stata testata ad angolazioni di 45°, 60° e 90° mediante un modello sperimentale creato specificatamente. Risultati e conclusioni Dall’analisi dei dati e emersa una buona resistenza alla fatica ciclica per quanto concerne le sistematiche ProFile e Twi…
Radiation defects and transition ions interaction in magnesium oxide
2007
Abstract The absorption spectra of nickel and manganese doped and pure MgO single crystals were investigated before and after fast neutron irradiation and after annealing. It is shown that the fast neutron irradiation leads to the formation of two types complex center: “Me 2+ –F + (or F) center” and “Me 3+ –V Mg ”. From the behavior of the ∼570 and ∼357 nm absorption bands during annealing the activation energies of the corresponding defects are determined. The obtained activation energy values ( E a
A two-detector spectrometer for measurements of Doppler broadened positron annihilation spectra
2004
Abstract A two-detector spectrometer for measurements of Doppler broadened positron annihilation spectra has been constructed and tested. The energy difference of the annihilation quanta is measured in the analogue, not in the digital manner. The peak to background ratio in the measured spectra is of the order of 10 6 , the FWHM representing the energy resolution, equals to 1.1 keV , thus enabling the very subtle physical effects to be revealed. Some information on electronic structure of the investigated 3-d metals (Ti, V, Cr, Fe, Ni, Cu and Zn) has been determined using this spectrometer. It has been shown that the apparatus permits to detect the impurity-vacancy pairs in dilute nickel al…
EXAFS study of mixed nickel molybdenum oxide thin films at the Ni and Mo K-edges
2004
Mixed nickel molybdenum oxide thin films were produced by DC magnetron co-sputtering technique with the nickel content about 8, 16 and 25 at%. X-ray absorption spectroscopy at the Ni and Mo K-edges was used to study the local atomic structure in the films. The best-fit analysis of the EXAFS signals suggests that (i) the films are amorphous, except for the highest nickel content (25 at%), at which a segregation of NiO phase was observed; (ii) nickel and molybdenum atoms are octahedrally coordinated by oxygen atoms. Opposite to the NiO6 octahedra, the MoO6 octahedra are strongly distorted, that results in an existence of two groups of oxygen atoms—four nearest at B1.76 ( A and two distant at …
Calculation of beta-decay properties of neutron-rich nickel isotopes
1989
Gamow-Tellerβ-decay properties of neutron-rich Ni isotopes have been calculated in the RPA with Nilsson model wave functions. On the basis of the results for the known isotopes67–69Ni, half-lives and neutron-emission probabilities for70–82Ni are predicted and compared to earlier model estimates. Possible implications onr-process nucleosynthesis are discussed.
A Preliminary BeppoSAX Study of the (Bright) Atoll Source GX 9+1
2003
We report the preliminary results of a 350 ks BeppoSAX observation of the bright atoll source GX 9+1. In the field of view of the MECS instrument we discovered a X-ray pulsar, designated SAX J1802.7 - 2017, at an angular distance from GX 9+1 of ∼ 22 ′ . Since the X-ray emission of SAX J1802.7 - 2017 contaminates the energy spectrum above 10 keV we studied the energy spectrum of GX 9+1 in the energy band 0.1 - 10keV. We selected four regions in the color-color diagram and extracted one spectrum from each region. A bump below 1keV is present in the spectra using a model composed by a Comptonized component absorbed by neutral matter having an equivalent hydrogen column of 1.5 x 10 22 cm -2 . T…
Finely tuned nickel complexes as highly active catalysts affording branched polyethylene of high molecular weight: 1-(2,6-Dibenzhydryl-4- methoxyphen…
2018
Abstract A series of unsymmetrical 1,2-bis(imino)acenaphthenenickel(II) halides containing N-2,6-dibenzhydryl-4-methoxyphenyl – a single bulky group with adjusted electron donating properties – has been synthesized and characterized. These compounds adopt distorted tetrahedral geometry and their 1H NMR spectra show the paramagnetically shifted peaks. On activation with a low amount of Et2AlCl or ethylaluminum sesquichloride (EASC), these nickel complexes display high activity in ethylene polymerization, yielding the polyethylene of high molecular weight. They are also stable at elevated temperature; superb activity of 2.51 × 106 g of PE (mol of Ni)−1 h−1 can be attained at 90 °C. The result…
Investigation of polymer organic deposit formed on nickel phosphate in oxidative dehydrogenation of ethylbenzene
1997
Abstract Several polymer organic deposits (PODS) had been obtained by heating of nickel polyphosphate (NiP) at 720 K for 1, 4, or 10 h in a stream of helium (carrier gas) containing 20% of (ethylbenzene : oxygen= 1: 0.5] mixture. The samples were tested in oxidative dehydrogenation (OD) of ethylbenzene (EB) to styrene, before and after their separation from the inorganic part of NiP as catalysts. Some functional groups or bonds, important for enhancement of styrene yield, have been found in the PODS. The POD obtained after 10-h coking of NiP, containing a mixture of both insoluble fused-ring and soluble-in-pyridine macromolecules, provided with at least two types of catalytically active cen…
THE MAGNETIC SUSCEPTIBILITY OF MOLTEN NICKEL(II) COMPLEXES
1957
Abstract The bis-( N -alkylsalicylaldimine) - nickel (II) complexes, which are diamagnetic in the solid state, become paramagnetic with moments ranging from 0.8 to 1.15 B.M. in the molten state.