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The optical properties of V 2 O 3 thin films are investigated across the insulator-to-metal transition and in the metallic state. The spectral weight transfer observed across the transition, over an energy scale of 5 eV, is consistent with the Mott-Hubbard model for correlated electron systems. In the metallic phase, a strong Drude peak is observed, which exhibits a pronounced temperature dependence related to the transfer of states from the Hubbard bands to the quasiparticle peaks as the temperature is reduced. The analysis of the far-infrared spectra reveals signatures of strong electronic correlations in V 2 O 3. Finally, a comparison to VO 2 data is presented.

We report the existence of two competing mechanisms in the current-driven electrical breakdown of vanadium sesquioxide (V 2 O 3) and vanadium dioxide (VO 2) nanodevices. Our experiments and simulations show that the competition between a purely-electronic mechanism (PE) and an electro-thermal (ET) mechanism, suppressed in nanoscale devices, explains the current driven insulator-to-metal phase transition (IMT). We find that the relative contribution of PE and ET effects is dictated by thermal coupling and resistivity, a discovery which disambiguates a long-standing controversy surrounding the physical nature of the current-driven IMT in vanadium oxides. Furthermore, we show that the electro-thermally driven IMT occurs through a nanoscopic surface-confined filament. This nano-confined filament has a very large thermal gradient, thus generating a large Seebeckeffect electric field.

A major challenge for the structural study of the seven-transmembrane G-protein-coupled receptors is to obtain a sufficient amount of purified protein at the milligram level, which is required for either nuclear magnetic resonance (NMR) spectroscopy or X-ray crystallography. In order to develop a high-yield and cost-effective method, and also to obtain preliminary structural information for the computer modeling of the three-dimensional receptor structural model, a highly hydrophobic peptide from human cannabinoid subtype 2 receptor CB2(65-101), was chosen to develop high-yield membrane protein expression and purification methods. The peptide included the second transmembrane helix with the associated loop regions of the CB2 receptor. It was over-expressed in Escherichia coli, with a modified TrpDelta LE1413 (TrpLE) leading fusion sequence and a nine-histidine tag, and was then separated and purified from the tag in a preparative scale. An experimental protocol for the chemical cleavage of membrane protein fragment was developed using cyanogen bromide to remove the TrpLE tag from the hydrophobic fusion protein. In addition, protein uniformly labeled with isotopic 15N was obtained by expression in 15N-enriched minimum media. The developed and optimized preparation scheme of expression, cleavage, and purification provided a sufficient amount of peptide for NMR structure analysis and other biophysical studies that will be reported elsewhere. The process of fusion protein cleavage following purification was monitored by high-performance liquid chromatography (HPLC) and mass spectrometry (MS), and the final sample was validated by MS and circular dichroism experiments.

Deadlock detection algorithms for distributed systems have been studied thoroughly for many years. However, many of them either are incorrect or too expensive in terms of time and/or space Complexity. One problem with previous work is that deadlock resolution is often overlooked.Another problem is the insufficient attention given to the characteristics of the wait-for model that is employed. The former problem introduces incorrectness into many algorithms after deadlocks have been resolved, whereas the latter results in inefficient algorithms.In this paper, a theoretical framework for wait-for systems is provided, and general characteristics of a correct algorithm for deadlock detection and resolution are presented. It is shown that the computational upper bounds (number of messages) for deadlock detection and resolution are both O(n3) in the worst case when n transactions are involved. This result is better than previous ones, which often are even exponential. In addition, two correct deadlock detection and resolution algorithms are described which both achieve these upper bounds.