Superconductivity above 30 K achieved in dense scandium

Superconductivity is one of most intriguing quantum phenomena, and the quest for elemental superconductors with high critical temperature (Tc) is of great scientific significance due to their relatively simple material composition and the underlying mechanism. Here we report the experimental discovery of densely compressed scandium (Sc) becoming the first elemental superconductor with Tc breaking into 30 K range, which is comparable to the Tc values of the classic La-Ba-Cu-O or LaFeAsO superconductors. Our results show that Tconset of Sc increases from ~3 K at around 43 GPa to ~32 K at about 283 GPa (Tczero ~ 31 K), which is well above liquid neon temperature. Interestingly measured Tc shows no sign of saturation up to the maximum pressure achieved in our experiments, indicating that Tc might be even higher upon further compression.Comment: 22 pages, 16 figure

Superconductivity above 70 K observed in lutetium polyhydrides

The binary polyhydrides of heavy rare earth lutetium that shares a similar valence electron configuration to lanthanum have been experimentally discovered to be superconductive. The lutetium polyhydrides were successfully synthesized at high pressure and high temperature conditions using a diamond anvil cell in combinations with the in-situ high pressure laser heating technique. The resistance measurements as a function of temperature were performed at the same pressure of synthesis in order to study the transitions of superconductivity (SC). The superconducting transition with a maximum onset temperature (Tc) 71 K was observed at pressure of 218 GPa in the experiments. The Tc decreased to 65 K when pressure was at 181 GPa. From the evolution of SC at applied magnetic fields, the upper critical field at zero temperature {\mu}0Hc2(0) was obtained to be ~36 Tesla. The in-situ high pressure X-ray diffraction experiments imply that the high Tc SC should arise from the Lu4H23 phase with Pm-3n symmetry that forms a new type of hydrogen cage framework different from those reported for previous light rare earth polyhydride superconductors

Design of amphotericin B oral formulation for antifungal therapy

Amphotericin B (AmB) remains the “gold standard” for systemic antifungal therapy, even though new drugs are emerging as the attractive antifungal agents. Since AmB has negligible oral absorption as a consequence of its unfavorable physicochemical characterizations, its use is restricted to parenteral administration which is accompanied by severe side effects. As greater understanding of the gastrointestinal tract has developed, the advanced drug delivery systems are emerging with the potential to overcome the barriers of AmB oral delivery. Much research has demonstrated that oral AmB formulations such as lipid formulations may have beneficial therapeutic efficacy with reduced adverse effects and suitable for clinical application. Here we reviewed the different formulation strategies to enhance oral drug efficacy, and discussed the current trends and future perspectives for AmB oral administration in the treatment of antifungal infections

An Exact Algorithm Based on MaxSAT Reasoning for the Maximum Weight Clique Problem

International audienceno abstrac

Combining MaxSAT Reasoning and Incremental Upper Bound for the Maximum Clique Problem

International audienceno abstrac

Incremental Upper Bound for the Maximum Clique Problem

International audienceThe maximum clique problem (MaxClique for short) consists of searching for a maximum complete subgraph in a graph. A branch-and-bound (BnB) MaxClique algorithm computes an upper bound of the number of vertices of a maximum clique at every search tree node, to prune the subtree rooted at the node. Existing upper bounds are usually computed from scratch at every search tree node. In this paper, we define an incremental upper bound, called IncUB, which is derived efficiently from previous searches instead of from scratch. Then, we describe a newBnB MaxClique algorithm, called IncMC2, which uses graph coloring and MaxSAT reasoning to filter out the vertices that do not need to be branched on, and uses IncUB to prune the remaining branches. Our experimental results show that IncMC2 is significantly faster than algorithms such as BBMC and IncMaxCLQ. Finally, we carry out experiments to provide evidence that the performance of IncMC2 is due to IncUB

Estimation of Yield Function for Anisotropic Aggregate of FCC Crystallites

In this paper, we give an simple but approximate yield surface for single FCC crystals in Hill’s criterion form by Schmid’s law and nonlinear optimization theory. Assuming that all FCC crystallites in a polycrystal have the same (current) critical resolved shear stress τc for slip, we derive two closed but approximate yield functions through the orientational averaging of all FCC crystallites’ yield surfaces in the polycrystal. The effect of crystallography on the two yield functions are described by the orientation distribution function

Estimation of Yield Function for Anisotropic Aggregate of FCC Crystallites

In this paper, we give an simple but approximate yield surface for single FCC crystals in Hill’s criterion form by Schmid’s law and nonlinear optimization theory. Assuming that all FCC crystallites in a polycrystal have the same (current) critical resolved shear stress τc for slip, we derive two closed but approximate yield functions through the orientational averaging of all FCC crystallites’ yield surfaces in the polycrystal. The effect of crystallography on the two yield functions are described by the orientation distribution function