Results from the kaonic hydrogen X-ray measurement at DAFNE and outlook to future experiments

The $\overline{K}N$ system at rest plays a key role for the understanding of strong interaction of hadrons with strangeness involved. The experiment SIDDHARTA used X-ray spectroscopy of kaonic atoms to measure the strong interaction induced shift and width of the ground state. It was the first experiment on kaonic He3 and deuterium ever, kaonic hydrogen was measured with improved precision resulting in $\epsilon_{1s} = -283 \pm 36 \mbox{(stat)} \pm 6 \mbox{(syst)}$ eV and $\Gamma_{1s} = 541 \pm 89 \mbox{(stat)} \pm 22 \mbox{(syst)}$ eV. Additionally a scheme for an improved future experiment on kaonic deuterium is introduced in this contribution.     

Homogeneous Catalysts with a Mechanical (“Machine‐like”) Action

Molecular machines? The factors involved in and the fundamental nature of a “mechanical” action within molecular catalysis is explored in detail. Such mechanical homogeneous catalysts are rare but not unknown (see graphic). The spatial and temporal nature of their catalytic action is considered. Potential implications for mimicry of enzymes are discussed.

     

Statistical mechanics of combinatorial auctions

Combinatorial auctions are formulated as frustrated lattice gases on sparse random graphs, allowing the determination of the optimal revenue by methods of statistical physics. Transitions between computationally easy and hard regimes are found and interpreted in terms of the geometric structure of the space of solutions. We introduce an iterative algorithm to solve intermediate and large instances, and discuss competing states of optimal revenue and maximal number of satisfied bidders. The algorithm can be generalized to the hard phase and to more sophisticated auction protocols.     

Solution dynamics of the natural bioactive molecule capsaicin: a relaxation study

Nuclear magnetic resonance spectroscopy is a straightforward technique for studying molecular dynamics that range in timescale from picosecond (motions faster than molecular reorientation) to those that occur in real-time. This approach is important to highlight the behavior of bioactive molecules in solution, and to acquire information about action mechanisms and potential pharmacological effects. Proton and carbon-13 spin–lattice relaxation experiments were performed to calculate the reorientational correlation time for protonated carbons. Capsaicin showed complex dynamical properties and the results revealed two regions with different dynamical properties: the aliphatic region with fast reorientation motions and the aromatic region with slow motions.     

Temperature effects on the IR absorption bands of hydroxyl and deuteroxyl groups in silica glass

In this report we will show the changes of the band shape of the hydroxyl group (SiOH) infrared (IR) absorption band (～3670 cm^?1) in silica glass induced by lowering temperature in the range from 290 to 20 K. This band is considered as the overlap of several spectral components associated to the vibrational activity of hydroxyl groups in different bond configurations. By a suitable analysis of the experimental band profile in terms of different sub-bands, we studied the thermal evolution of each component and we reconsidered their assignations. For comparison we examined the SiOD absorption band (～2710 cm^?1) as a function of temperature as well. Our data can be interpreted as an evidence of a conversion process of free into H(D)-bonded SiOH(D) groups. Moreover, we estimated the ratio between the molar extinction coefficients of the two main species involved in this process finding that this ratio is appreciably influenced by the isotopic exchange.     

Improved morphology for epitaxial growth on 4° off-axis 4H-SiC substrates

A process optimization of the growth of silicon carbide (SiC) epilayers on 4° off-axis 4H-SiC substrates is reported. Process parameters such as growth temperature, C/Si ratio and temperature ramp-up conditions are optimized for the standard non-chlorinated growth in order to grow smooth epilayers without step bunching and triangular defects. The growth of 6-μm-thick n-type-doped epitaxial layers on 75-mm-diameter wafers is demonstrated as well as that of 20-μm-thick layer. The optimized process was then transferred to a chloride-based process and a growth rate of 28 μm/h was achieved without morphology degradation. A low growth temperature and a low C/Si ratio are the key parameters to reduce both the step bunching and the formation of triangular defects.     

Structure,chemical durability and crystallization behavior of incinerator-based glassy systems

Vitrification by melting is being proposed as a convenient method to solidify different kinds of silicate and other oxide-based inorganic wastes. Incinerator bottom and fly ashes have been mixed with glass cullet, feldspar and clay by-products as melting fluxing agents. Washing, drying, and grinding pre-treatments followed by melting at 1450 °C lead to the formation of glasses and glass-ceramics, depending on the starting materials composition and thermal treatment. The obtained glasses have been studied by SEM, chemical durability tests in aqueous and alkaline environment, leaching test (UNI 10802), and by differential thermal analysis. The glass-ceramics morphology was investigated by XRD and SEM. The results were explained by the structure of the glasses caused by the presence of different amount of modifiers in the glassy lattice. The obtained glasses show good chemical resistance, in particular in alkaline environment and thermal characterization highlighted that the materials are also suitable to obtain glass-ceramics.     

Cooper-pair pump as a quantized current source

A new charge quantization in a phase-polarized Cooper-pair pump is proposed, based on the topological properties of its Hamiltonian ground state over a three-dimensional parameter space P. The charge is quantized using a set of paths in P covering the surface of a torus, and is a multiple of the integer Chern index c1 of this surface. This quantization is asymptotic but the pumped charge converges rapidly to the quantized value with the increase in the path frequency. The topological nature of the current makes this Cooper-pair pump implementation an excellent candidate for a metrological current standard.     

Identification of Limonol Derivatives as Heat Shock Protein 90 (Hsp90) Inhibitors through a Multidisciplinary Approach

The identification of inhibitors of Hsp90 is currently a primary goal in the development of more effective drugs for the treatment of various types of multidrug resistant malignancies. In an attempt to identify new small molecules modulating the activity of Hsp90, we screened a small library of tetranortriterpenes. A high‐affinity interaction with Hsp90 inducible form was uncovered for eight of these compounds, five of which are described here for the first time. By monitoring the ATPase activity and the citrate synthase thermal induced aggregation, compound 1 (cedrelosin A), 3 (7α‐limonylacetate), and 5 (cedrelosin B), containing a limonol moiety, were found to be the most effective in compromising the Hsp90α chaperone activity. Consistent with these findings, the three compounds caused a depletion of c‐Raf and pAkt Hsp90 client proteins in HeLa and MCF/7 cell lines. Induced fit docking protocol and molecular dynamics were used to rationalize the structural basis of the biological activity of the limonol derivatives. Taken together, these results point to limonol‐derivatives as promising scaffolds for the design of novel Hsp90α inhibitors.