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41.
Prof. Dr. Skye Fortier José Veleta Dr. Amélie Pialat Jennifer Le Roy Kamran B. Ghiassi Prof. Dr. Marilyn M. Olmstead Dr. Alejandro Metta‐Magaña Prof. Dr. Muralee Murugesu Prof. Dr. Dino Villagrán 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(6):1931-1936
After more than 50 years, the synthesis and electronic structure of the first and only reported “U0 complex” [U(bipy)4] ( 1 ) has been reinvestigated. Additionally, its one‐electron reduced product [Na(THF)6][U(bipy)4] ( 2 ) has been newly discovered. High resolution crystallographic analyses combined with magnetic and computational data show that 1 and its derivative 2 are best described as highly reduced species containing mid‐to‐high‐valent uranium ligated by redox non‐innocent ligands. 相似文献
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Kamran Akhbari 《Journal of organometallic chemistry》2007,692(23):5109-5112
In the solid state, the Tl(I) complex of 4-hydroxybenzoate (HB−), [Tl(HB)]n (1), can be regarded as containing polymeric chains linked through 2 × η6 interactions of the Tl atoms with phenyl groups from adjacent units. The thallium atoms contain close TlI ? π (aromatic) contacts, thus attaining a total hapticity of 16 with environments TlO4C12. The unusually high coordination number in the this compound may reflect the capacity of Tl(I) to act as both a Lewis acid and a Lewis base. 相似文献
44.
Mujahid Kamran 《理论物理通讯》1984,3(2):189-202
Using the Regge pole phase rule for contrilbutions to both amplitudes the DAM is applied to πp elastic scattering in the plab≥10 GeV/c and |t|≤0.8(GeV/c)2 region. It is found that the DAM has a mixed success in describing πp scattering. The p contribution to both amplitudes is in accord with the DAM while the f-non-flip contribution does not have a peripheral zero.The Pomeron imaginary part is in accord with the DAM with a non-negligible Pomeron phase so that the DAM approximation Rep=O is unsatisfactory. There is also a Pomeron-flip contribution contrary to the expectation of the model. The O-flip contribution is taken into account and a small f-flip contribution i s also required. 相似文献
45.
Nonexistence of time‐periodic solutions of the Dirac equation in an axisymmetric black hole geometry
We prove that in the nonextreme Kerr‐Newman black hole geometry, the Dirac equation has no normalizable, time‐periodic solutions. A key tool is Chan‐drasekhar's separation of the Dirac equation in this geometry. A similar nonexistence theorem is established in a more general class of stationary, axisymmetric metrics in which the Dirac equation is known to be separable. These results indicate that, in contrast to the classical situation of massive particle orbits, a quantum mechanical Dirac particle must either disappear into the black hole or escape to infinity. © 2000 John Wiley & Sons, Inc. 相似文献
46.
A novel multichannel vector sum phase shifter that is suitable for phased array antenna applications is demonstrated. Each channel is implemented using a distinct optical wavelength. Selective control of each channel is performed using an acousto-optic polarization coupler. The concept is successfully demonstrated for two individually controlled channels. For each channel, a continuously variable frequency linear phase shift is demonstrated between DC and 7 GHz, with the phasing range exceeding 100 degrees. 相似文献
47.
The removal of salt from porous building materials under the influence of an applied voltage gradient normally results in high pH gradients due to the formation of protons and hydroxyl ions at the electrodes. The formed acidic and alkaline regions not only lead to disintegration of the porous material, but also affect the salt transport. In this work we use ion exchange membranes between the electrodes and the porous material to prevent the protons and hydroxyl ions from intruding into the material. The porous material used in this study is fired clay brick, which has been saturated with a 4?mol/l sodium chloride solution prior to the desalination treatment. In order to experimentally determine the salt removal, we monitored the sodium ion concentration profiles across the material with nuclear magnetic resonance (NMR). In addition, we present theoretical predictions for the salt removal according to a model based on the Poisson?CNernst?CPlanck theory for ion transport. From the work reported here, we can conclude that the use of ion exchange membranes to desalinate porous building materials is not useful since it reduces the salt removal rate to such an extent that desalination with poultices, which is driven by diffusion only, is more efficient. The reason behind this is twofold. First, the ion exchange membranes provide a penalty for the ions to leave the material. Second, in the absence of acidic and alkaline regions, the salt concentration at the edges of the porous material will reduce to almost zero, which leads to a locally increased electrical resistance, and thus a reduction of the electrical field in the bulk of the material. Due to this reduction the effect of the applied voltage gradient across the material vanishes, and the salt removal is limited by diffusion. 相似文献
48.
Effect of deep cryogenic treatment on the formation of nano-sized carbides and the wear behavior of D2 tool steel
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The effect of deep cryogenic treatment on the microstructure, hardness, and wear behavior of D2 tool steel was studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), hardness test, pin-on-disk wear test, and the reciprocating pin-on-flat wear test. The results show that deep cryogenic treatment eliminates retained austenite, makes a better carbide distribution, and increases the carbide content. Furthermore, some new nano-sized carbides form during the deep cryogenic treatment, thereby increasing the hardness and improving the wear behavior of the samples. 相似文献
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50.
Kamran Ali Michael Reissner Walter Steiner Michael Feuerbacher 《Hyperfine Interactions》2012,207(1-3):109-112
New complex metallic alloys of the Taylor phase Al3Mn with 8, 10 and 12% Fe substitution are investigated by 57Fe M?ssbauer spectroscopy. Two groups of subspectra, with different hyperfine parameters are obtained, and are allocated to Fe sites with only Al nearest neighbors and Fe sites with both Al and Mn in the first shell. No difference between crystalline and quasicrystalline compounds is found indicating that long range periodicity plays a minor role. 相似文献