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81.
R. A. Briceñ o T. D. Cohen S. Coito J. J. Dudek E. Eichten C. S. Fischer M. Fritsch W. Gradl A. Jackura M. Kornicer G. Krein R. F. Lebed F. A. Machado R. E. Mitchell C. J. Morningstar M. Peardon M. R. Pennington K. Peters J. M. Richard C. P. Shen M. R. Shepherd T. Skwarnicki E. S. Swanson A. P. Szczepaniak C. Z. Yuan 《中国物理C(英文版)》2016,40(4):042001-042001
The last few years have been witness to a proliferation of new results concerning heavy exotic hadrons.Experimentally, many new signals have been discovered that could be pointing towards the existence of tetraquarks,pentaquarks, and other exotic configurations of quarks and gluons. Theoretically, advances in lattice field theory techniques place us at the cusp of understanding complex coupled-channel phenomena, modelling grows more sophisticated, and effective field theories are being applied to an ever greater range of situations. It is thus an opportune time to evaluate the status of the field. In the following, a series of high priority experimental and theoretical issues concerning heavy exotic hadrons is presented. 相似文献
82.
Dobrzynski Maciej Herman Katarzyna Bryla Ewelina Fita Katarzyna Dudek Krzysztof Kowalczyk-Zajac Malgorzata Szymonowicz Maria Rybak Zbigniew Korczynski Mariusz Wiglusz Rafal J. 《Journal of Thermal Analysis and Calorimetry》2019,135(6):3123-3128
Journal of Thermal Analysis and Calorimetry - An use of a polymerization lamp to irradiate chemically hardened glass-ionomer materials may improve their properties and accelerate the setting time.... 相似文献
83.
John W-P. Lin Les P. Dudek 《Journal of polymer science. Part A, Polymer chemistry》1985,23(5):1589-1597
Thermal treatment of novel poly(copper 2,3,9,10,16,17,23,24-octacyanophthalocyanine), PCOCP, has been carried out at different temperatures in an inert atmosphere. As polyacrylonitrile, the polymer can be thermally cyclized through the cyano groups to produce semiconductive and conductive materials. Polymeric copper octacyanophthalocyanine material with a conductivity as high as 5–8 (Ω cm)-1 was prepared. Weight loss, electrical data, infrared, and photoacoustic results of the thermally treated copper octacyanophthalocyanine polymer are discussed. 相似文献
84.
Mass spectra of nucleic acid derivatives. Pyrimidines 总被引:3,自引:0,他引:3
85.
86.
Synthesis of ferrocenethiols containing oligo(phenylenevinylene) bridges and their characterization on gold electrodes 总被引:1,自引:0,他引:1
Ferrocene-terminated oligo(phenylenevinylene) (OPV) methyl thiols have been prepared by orthogonal coupling of phenylene monomers. Ethoxy substituents on the phenyl rings improve the solubility of OPV, enabling the synthesis of longer oligomers. Self-assembled monolayers containing a mixture of a ferrocene OPV methyl thiol and a diluent alkanethiol were deposited on gold. A cyclic voltammetric study of monolayers containing oligomers of the same length with and without ethoxy solubilizing groups reveals that both solubilized and unsolubilized oligomers form well-packed self-assembled monolayers. Changing the position of the solubilizing groups on an oligomer chain does not preclude packing of the oligomer in the monolayer. Conventional chronoamperometry, which can be used to measure rate constants up to approximately 10(4) s(-1), is too slow to measure the electron-transfer rate through these oligomers over distances up to 35 A. OPV bridges are expected to be highly conjugated unlike oligo(phenyleneethynylene) bridges, which may be only partially conjugated because of rotation of the phenyl rings about the ethynylene bonds. Because of its high conjugation, OPV may prove useful as a molecular wire. 相似文献
87.
The (?, ψ) energy surface of blocked alanine (N-acetyl–N′-methyl alanineamide) was calculated at the Hartree-Fock (HF)/6-31G* level using ab initio molecular orbital theory. A collection of six electrostatic models was constructed, and the term electrostatic model was used to refer to (1) a set of atomic charge densities, each unable to deform with conformation; and (2) a rule for estimating the electrostatic interaction energy between a pair of atomic charge densities. In addition to two partial charge and three multipole electrostatic models, this collection includes one extremely detailed model, which we refer to as nonspherical CPK. For each of these six electrostatic models, parameters—in the form of partial charges, atomic multipoles, or generalized atomic densities—were calculated from the HF/6-31G* wave functions whose energies define the ab initio energy surface. This calculation of parameters was complicated by a problem that was found to originate from the locking in of a set of atomic charge densities, each of which contains a small polarization-induced deformation from its idealized unpolarized state. It was observed that the collective contribution of these small polarization-induced deformations to electrostatic energy differences between conformations can become large relative to ab initio energy differences between conformations. For each of the six electrostatic models, this contribution was reduced by an averaging of atomic charge densities (or electrostatic energy surfaces) over a large collection of conformations. The ab initio energy surface was used as a target with respect to which relative accuracies were determined for the six electrostatic models. A collection of 42 more complete molecular mechanics models was created by combining each of our six electrostatic models with a collection of seven models of repulsion + dispersion + intrinsic torsional energy, chosen to provide a representative sample of functional forms and parameter sets. A measure of distance was defined between model and ab initio energy surfaces; and distances were calculated for each of our 42 molecular mechanics models. For most of our 12 standard molecular mechanics models, the average error between model and ab initio energy surfaces is greater than 1.5 kcal/mol. This error is decreased by (1) careful treatment of the nonspherical nature of atomic charge densities, and (2) accurate representation of electrostatic interaction energies of types 1—2 and 1—3. This result suggests an electrostatic origin for at least part of the error between standard model and ab initio energy surfaces. Given the range of functional forms that is used by the current generation of protein potential functions, these errors cannot be corrected by compensating for errors in other energy components. © 1995 by John Wiley & Sons, Inc. 相似文献
88.
J. Dudek W. Dudek E. Ruchowska J. Skalski 《Zeitschrift für Physik A Hadrons and Nuclei》1980,294(4):341-350
Deformed Nilsson and Woods-Saxon potentials were employed for generating single particle states used henceforth for calculating the inertia tensor (cranking model and monopole pairing) and the collective energy surfaces (Strutinsky method). The deformation was parametrized in terms of quadrupole and hexadecapole degrees of freedom. The classical energy expression obtained from the inertia tensor and energy surfaces was quantized and the resulting stationary Schrödinger equation was solved using the approximate method. The secondI π=0 2 + collective level energies were calculated for the Rare Earth and Actinide nuclei and the results compared with the experimental data. The vibrational level energies agree with the experimental ones much better for spherical nuclei for both single particle potentials; the discrepancies for deformed nuclei overestimate the experimental results by roughly a factor of two. It is argued that coupling of the axially symmetric quadrupole degrees of freedom to non-axial and hexadecapole ones does not affect the conclusions about systematically too low mass parameter values. The alternative explanation of the systematic deviations from the 0 2 + level energies could be a systematically too high stiffness of the energy surfaces obtained with the Strutinsky method. 相似文献
89.
H. J. Dudek und W. Bunk 《Fresenius' Journal of Analytical Chemistry》1987,329(2-3):422-428
Zusammenfassung Die in situ-Experimentalanlage für Werkstoffanalyse (ISEWA) der DFVLR wurde zur oberflächenanalytischen Untersuchung der im Mikrobereich enthaltenen Informationen über die Ursachen des Werkstoffversagens entwickelt. Die ISEWA soll vor allem bei der Untersuchung der mechanischen Eigenschaften, des Umgebungseinflusses und der Herstellungsprobleme von Verbundwerkstoffen eingesetzt werden. Es wurden das Gesamtkonzept der ISEWA, Konstruktionsdetails zum Probentransport und zur Probeneinspannung sowie einige Experimente über die vakuumtechnischen und meßtechnischen Voraussetzungen für den Einsatz der Apparatur beschrieben. Die Anwendung der ISEWA für die Lösung von Entwicklungsaufgaben der Werkstoffe der Luft- und Raumfahrt wurde an Beispielen aus der Pulvermetallurgie des Titans und an der Korngrenzenversprödung von Aluminium-Lithium-Legierungen demonstriert.
The DFVLR in situ equipment for surface analytical investigations in materials science
Summary For application of surface analysis in the development of aerospace materials an in situ equipment was developed. It consists of two UHV vessels: one for tests of mechanical properties and one for coating and annealing. Both vacuum chambers are connected with each other and with an Auger microprobe by a perpendicular arranged sample transport system. The chamber for the mechanical test experiments is integrated into a frame of a servo-hydraulical pull test machine, the sample holder of which projects into the chamber by UHV bellows. Samples can be taken from a sample magazine, carried to the sample holder of the pull test machine and mounted there under UHV conditions. The samples can be tested under definite load, environmental and temperature conditions. After breaking the sample can be brought by the transport system into the Auger microprobe and there the fracture surface is investigated by AES and XPS.Details on the construction of the equipment, especially on the sample transport system and on the sample holder are reported. The application of the in situ equipment is demonstrated by two examples: the powder metallurgy of titanium and the grain boundary embrittlement in aluminium-lithium alloys.相似文献
90.