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101.
M. Bangal S. Ashtaputre S. Marathe A. Ethiraj N. Hebalkar S. W. Gosavi J. Urban S. K. Kulkarni 《Hyperfine Interactions》2005,160(1-4):81-94
Semiconductor nanoparticles exhibit size dependent properties, when their size is comparable to the size of Bohr diameter
for exciton. This can be exploited to increase fluorescence efficiency or increase the internal magnetic field strength in
doped semiconductors. Nanoparticles are usually unstable and can aggregate. It is therefore necessary to protect them. Surface
passivation using capping molecules or by making core–shell particles are some useful ways. Here synthesis and results on
doped and un-doped nanoparticles of ZnS, CdS and ZnO will be discussed. We shall present results on core–shell particles using
some of these nanoparticles and also discuss briefly the effect of Mn doping on hyperfine interactions in case of CdS nanoparticles. 相似文献
102.
103.
Ts. Venkova T. Morek G. V. Martí H. Schnare A. Krämer-Flecken W. Gast A. Georgiev G. Hebbinghaus R. M. Lieder G. Sletten K. M. Spohr K. H. Maier W. Urban 《Zeitschrift für Physik A Hadrons and Nuclei》1993,344(4):417-423
Two new isomers have been observed in180Os. A high-K isomer withI, K ≧20 and a half-life ofT 1/2=12+4 ns have been established. It deexcites via two transitions into the 18+ level of the yrare band indicating an unusually smallK-hindrance factor. Evidence for an isomer withI, K>16 and a half-life ofT 1/2=41±10 ns was found. A half-life of 17±3 ns was measured for the previously known 7? state at 1862 keV. The decay scheme of the previously known 7? isomer at 1928 keV has been extended and a revised version is presented. 相似文献
104.
105.
G. R. Strobl T. Engelke H. Meier G. Urban H. G. Zachmann R. Hosemann V. Mathot 《Colloid and polymer science》1982,260(4):394-403
Zusammenfassung Auf der Grundlage der Ergebnisse von Röntgenkleinwinkel-Streuexperimenten und elektroenenmikroskopischen Untersuchungen an verzweigtem Polyethylen wird ein neues Modell zum Ablauf des partiellen Kristallisierens und Schmelzens entwickelt. Im Modell wird der Aufbau der Lamellarstruktur als sukzessive Einschubkristallisation beschrieben, die durch die Konzentration an nichtkristallisierfähigen Einheiten in den amorphen Bereichen gesteuert wird. Die Kinetik der Einschubkristallisation läßt sich durch dilatometrische Experimente verfolgen. Aus vergleichenden Röntgenkleinwinkel- und Ramanstreuexperimenten kann auf eine Anreicherung der Cobausteine an den Lamellenoberflächen geschlossen werden.Preprint zur 30. Hauptversammlung der Kolloid-Gesellschaft, 6.–9. Oktober 1981 in Ulm. 相似文献
106.
H. Urban F. Zereini B. Skerstupp M. Tarkian 《Fresenius' Journal of Analytical Chemistry》1995,352(6):537-543
The chemical composition of phases in buttons obtained by nickel sulfide fire-assay during the determination of platinum-group elements (PGE) has been investigated by electron microprobe analysis. Different PGE-containing phases, due to varying flux constituents and species of added PGE, have been detected. By using sodium tetraborate as flux constituent and adding PGE as chlorides, in a cryptocrystalline Ni3S2 matrix with low PGE (mainly Rh and Ru) contents, Rh- and Ru-bearing nickel sulfides ((Ni7.68–7.80Ru0.84–0.90Rh0.35–0.43)9S8) and Ir alloys ((Ir,Pt,Os)0.56–0.62(Ru,Rh)0.25–0.28Ni0.12–0.19) are found. Treatment with lithium tetraborate leads to a Ni3S2 matrix exhibiting slightly higher Rh and Ru contents, with inclusions of nickel-rhodium sulfides (Ni8Rh4S9) and platinumnickel alloys (Pt0.45Ni0.36–0.39Ru0.11–0.14Rh0.05). Finely dispersed metallic colloidals from an automobile catalyst, with platinum and rhodium as main components, have given only platinum-nickel alloys (Pt1–xNix). Considerable losses of PGE during analytical steps following the fire assay are expected when their contents in sulfidic phases, which are more likely to be dissolved, are high. 相似文献
107.
A novel imaging mode for high-resolution transmission electron microscopy is described. It is based on the adjustment of a negative value of the spherical aberration C S of the objective lens of a transmission electron microscope equipped with a multipole aberration corrector system. Negative spherical aberration applied together with an overfocus yields high-resolution images with bright-atom contrast. Compared to all kinds of images taken in conventional transmission electron microscopes, where the then unavoidable positive spherical aberration is combined with an underfocus, the contrast is dramatically increased. This effect can only be understood on the basis of a full nonlinear imaging theory. Calculations show that the nonlinear contrast contributions diminish the image contrast relative to the linear image for a positive-C S setting whereas they reinforce the image contrast relative to the linear image for a negative-C S setting. The application of the new mode to the imaging of oxygen in SrTiO3 and YBa2Cu3O7 demonstrates the benefit to materials science investigations. It allows us to image directly, without further image processing, strongly scattering heavy-atom columns together with weakly scattering light-atom columns. 相似文献
108.
This analysis is concerned with the continuous, deterministic case of an inventory system in which the demand rate of an item is of a polynomial functional form, dependent on the inventory level. Differential and integral calculus are used to find the inventory function with respect to time. From this, the objective function (to maximize average profit per unit time) is developed. For the continuous, multiperiod situation, a non-linear programming algorithm—separable programming—is utilized to determine the optimal order level (the quantity to order up to) and the order point (the quantity at which an order is placed). A numeric example and a sensitivity analysis are also presented. 相似文献
109.
A. L. S. Angelis J. Antos M. Beaulieu H. Beker G. Briskin J. Bystricky M. -G. Catanesi P. Cerello S. Dagan G. Dellacasa M. Diehl S. Di Liberto B. Dolgoshein M. Esten C. W. Fabjan A. Gaidot M. Gallio P. Giubellino U. Goerlach C. Guerra L. -A. Hamel S. Konovalov I. Kralik G. London F. Martelli J. -P. Martin M. Masera M. -A. Mazzoni F. Meddi M. -T. Muciaccia S. Muraviev A. Nomerotsky Y. Oren J. -P. Pansart G. Poulard L. Ramello L. Riccati G. Rosa L. Sandor M. Sarris E. Scomparin A. Shmeleva S. Simone S. Smirnov P. Taras J. Urban E. Vercellin 《The European Physical Journal C - Particles and Fields》1998,5(1):63-75
Results are presented on and production in p–W and S–W interactions at 200 GeV/c/nucleon measured via the dimuon decay in a large kinematic region. The data are normalized to
the charged particle multiplicity in the same rapidity interval. They have been collected using the HELIOS/3 muon spectrometer
at the CERN SPS. The ratio , where is the relevant resonance branching fraction, increases between proton and sulphur projectiles, and is somewhat enhanced going from peripheral to central
S–W interactions. This results from an increase in the number of produced 's per charged particle. The ratio is measured in different intervals of p and rapidity. It is not clearly dependent on p, but is larger at higher rapidities. production, likewise normalized to charged multiplicity, is significantly lower in S–W compared to p–W interactions.
Received: 27 October 1997 / Revised version: 5 March 1998 / Published online: 13 July 1998 相似文献
110.