66 research outputs found
Superconductivity in a Molecular Metal Cluster Compound
Compelling evidence for band-type conductivity and even bulk
superconductivity below K has been found in
Ga-NMR experiments in crystalline ordered, giant Ga
cluster-compounds. This material appears to represent the first realization of
a theoretical model proposed by Friedel in 1992 for superconductivity in
ordered arrays of weakly coupled, identical metal nanoparticles.Comment: 5 pages, 4 figure
Muon Spin Relaxation Studies of Superconductivity in a Crystalline Array of Weakly Coupled Metal Nanoparticles
We report Muon Spin Relaxation studies in weak transverse fields of the
superconductivity in the metal cluster compound,
Ga[N(SiMe)]-LiBr(thf)2toluene. The temperature and field dependence of the muon spin relaxation
rate and Knight shift clearly evidence type II bulk superconductivity below
K, with T,
T, and weak flux pinning. The data
are well described by the s-wave BCS model with weak electron-phonon coupling
in the clean limit. A qualitative explanation for the conduction mechanism in
this novel type of narrow band superconductor is presented.Comment: 4 figures, 5 page
SPECT- and PET-Based Approaches for Noninvasive Diagnosis of Acute Renal Allograft Rejection
Molecular imaging techniques such as single photon emission computed tomography (SPECT) or positron emission tomography are promising tools for noninvasive diagnosis of acute allograft rejection (AR). Given the importance of renal transplantation and the limitation of available donors, detailed analysis of factors that affect transplant survival is important. Episodes of acute allograft rejection are a negative prognostic factor for long-term graft survival. Invasive core needle biopsies are still the âgoldstandardâ in rejection diagnostics. Nevertheless, they are cumbersome to the patient and carry the risk of significant graft injury. Notably, they cannot be performed on patients taking anticoagulant drugs. Therefore, a noninvasive tool assessing the whole organ for specific and fast detection of acute allograft rejection is desirable. We herein review SPECT- and PET-based approaches for noninvasive molecular imaging-based diagnostics of acute transplant rejection
Al13Hâ: Hydrogen atom site selectivity and the shell model
Using a combination of anion photoelectron spectroscopy and density functional theory calculations, we explored the influence of the shell model on H atom site selectivity in Al13Hâ. Photoelectron spectra revealed that Al13Hâ has two anionic isomers and for both of them provided vertical detachment energies (VDEs). Theoretical calculations found that the structures of these anionic isomers differ by the position of the hydrogen atom. In one, the hydrogen atom is radially bonded, while in the other, hydrogen caps a triangular face. VDEs for both anionic isomers as well as other energetic relationships were also calculated. Comparison of the measured versus calculated VDE values permitted the structure of each isomer to be confirmed and correlated with its observed photoelectron spectrum. Shell model, electron-counting considerations correctly predicted the relative stabilities of the anionic isomers and identified the stable structure of neutral Al13H
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