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81.
We present a general method for studying front propagation in nonlinear systems with a global constraint in the language of hybrid tank models. The method is illustrated in the case of semiconductor superlattices, where the dynamics of the electron accumulation and depletion fronts shows complex spatiotemporal patterns, including chaos. We show that this behavior may be elegantly explained by a tank model, for which analytical results on the emergence of chaos are available. In particular, for the case of three tanks the bifurcation scenario is characterized by a modified version of the one-dimensional iterated tent map. 相似文献
82.
J. Burmester L. Criegee H.C. Dehne K. Derikum R. Devenish G. Flügge J.D. Fox G. Franke Ch. Gerke P. Harms G. Horlitz Th. Kahl G. Knies M. Rössler R. Schmitz U. Timm H. Wahl K. Wacker 《Physics letters. [Part B]》1977,68(3):301-304
Events of the type have been observed in the magnetic detector PLUTO at the storage ring DORIS at DESY. The data support the hypothesis of the pair production of heavy leptons, and allow to determine decay parameters. Decay rates into muons and electrons are equal within error, and argue for a new lepton number of the heavy lepton. 相似文献
83.
Ch. Berger H. Genzel R. Grigull W. Lackas F. Raupach A. Klovning E. Lillestöl E. Lillethun J.A. Skard H. Ackermann G. Alexander F. Barreiro J. Bürger L. Criegee H.C. Dehne R. Devenish A. Eskreys K. Wacker 《Physics letters. [Part B]》1979,89(1):120-124
We present the first data on photon-photon annihilation into hadrons for CM energies > 1 GeV obtained with the detector PLUTO at the e+e? storage ring PETRA. Cross sections are extracted using an inelastic eγ scattering formalism. The results are compared to expectations from Regge-like models. 相似文献
84.
Zero-phonon linewidth and phonon satellites in the optical absorption of nanowire-based quantum dots
The optical properties of quantum dots embedded in a catalytically grown semiconductor nanowire are studied theoretically. In comparison to dots in a bulk environment, the excitonic absorption is strongly modified by the one-dimensional character of the nanowire phonon spectrum. In addition to pronounced satellite peaks due to phonon-assisted absorption, we find a finite width of the zero-phonon line already in the lowest-order calculation. 相似文献
85.
Dr. Nicole A. Vanagas Dr. Robert F. Higgins Jennifer N. Wacker Dane Romar C. Asuigui Evan Warzecha Dr. Stosh A. Kozimor Prof. Sarah L. Stoll Prof. Eric J. Schelter Dr. Jeffery A. Bertke Prof. Karah E. Knope 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(26):5872-5886
Uranium(IV) complexation by 2-furoic acid (2-FA) was examined to better understand the effects of ligand identity and reaction conditions on species formation and stability. Five compounds were isolated: [UCl2(2-FA)2(H2O)2]n ( 1 ), [U4Cl10O2(THF)6(2-FA)2] ⋅ 2 THF ( 2 ), [U6O4(OH)4(H2O)3(2-FA)12] ⋅ 7 THF ⋅ H2O ( 3 ), [U6O4(OH)4(H2O)2(2-FA)12] ⋅ 8.76 H2O ( 4 ), and [U38Cl42O54(OH)2(H2O)20] ⋅ m H2O ⋅ n THF ( 5 ). The structures were determined by single-crystal X-ray diffraction and further characterized by Raman, IR, and optical absorption spectroscopy. The thermal stability and magnetic behavior of the compounds were also examined. Variations in the synthetic conditions led to notable differences in the structural units observed in the solid state. At low H2O/THF ratios, a tetranuclear oxo-bridged [U4O2] core was isolated. Aging of this solution resulted in the formation a U38 oxo cluster capped by chloro and water ligands. However, at increasing water concentrations only hexanuclear units were observed. In all cases, at temperatures of 100–120 °C, UO2 nanoparticles formed. 相似文献
86.
J. Wacker 《Journal of Radioanalytical and Nuclear Chemistry》2001,249(1):103-108
Traditional methods of quantitation of radioactive isotopes includeradioactivity counting and thermal ion mass spectrometry (TIMS). These techniquesrequire extensive matrix separation and sample purification methods beforeunequivocal identification of specific isotopes and their relative abundanceis possible. Counting techniques become very time consuming when the half-lifeof the target analyte is very long or the concentration of the analyte low.Atom counting using ICP-MS meets the nuclear industry requirements for manyactinides and their daughter products. Recent improvements in quadrupole ICP-MSsignal-to-background have resulted in attogram mass detection capability andimproved analysis of shorter half-life isotopes. 相似文献
87.
Leonhard Wacker 《欧洲无机化学杂志》1902,35(4):3920-3928
88.
A methodology is proposed for predicting the effective thermal conductivity of dilute suspensions of nanoparticles (nanofluids) based on rheology.The methodology uses the rheological data to infer microstructures of nanoparticles quantitatively,which is then incorporated into the conventional Hamilton-Crosser equation to predict the effective thermal conductivity of nanofluids.The methodology is experimentally validated using four types of nanofluids made of titania nanoparticles and titanate nanotubes dispersed in water and ethylene glycol.And the modified Hamilton-Crosser equation successfully predicted the effective thermal conductivity of the nanofluids. 相似文献
89.
90.