Welding high strength, ferritic steels for hydrogen service

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Out-of-equilibrium collective oscillation as phonon condensation in a model protein

In the first part of the present paper (theoretical), the activation of out-of-equilibrium collective oscillations of a macromolecule is described as a classical phonon condensation phenomenon. If a macromolecule is modeled as an open system, that is, it is subjected to an external energy supply and is in contact with a thermal bath to dissipate the excess energy, the internal nonlinear couplings among the normal modes make the system undergo a non-equilibrium phase transition when the energy input rate exceeds a threshold value. This transition takes place between a state where the energy is incoherently distributed among the normal modes, to a state where the input energy is channeled into the lowest frequency mode entailing a coherent oscillation of the entire molecule. The model put forward in the present work is derived as the classical counterpart of a quantum model proposed long time ago by H. Fr\"ohlich in the attempt to explain the huge speed of enzymatic reactions. In the second part of the present paper (experimental), we show that such a phenomenon is actually possible. Two different and complementary THz near-field spectroscopic techniques, a plasmonic rectenna, and a micro-wire near-field probe, have been used in two different labs to get rid of artefacts. By considering a aqueous solution of a model protein, the BSA (Bovine Serum Albumin), we found that this protein displays a remarkable absorption feature around 0.314 THz, when driven in a stationary out-of-thermal equilibrium state by means of optical pumping. The experimental outcomes are in very good qualitative agreement with the theory developed in the first part, and in excellent quantitative agreement with a theoretical result allowing to identify the observed spectral feature with a collective oscillation of the entire molecule.Comment: 49 pages, 10 figures; Physical Review X, (2018) in pres

Biological application of Compressed Sensing Tomography in the Scanning Electron Microscope

The three-dimensional tomographic reconstruction of a biological sample, namely collagen fibrils in human dermal tissue, was obtained from a set of projection-images acquired in the Scanning Electron Microscope. A tailored strategy for the transmission imaging mode was implemented in the microscope and proved effective in acquiring the projections needed for the tomographic reconstruction. Suitable projection alignment and Compressed Sensing formulation were used to overcome the limitations arising from the experimental acquisition strategy and to improve the reconstruction of the sample. The undetermined problem of structure reconstruction from a set of projections, limited in number and angular range, was indeed supported by exploiting the sparsity of the object projected in the electron microscopy images. In particular, the proposed system was able to preserve the reconstruction accuracy even in presence of a significant reduction of experimental projections

VLT-UVES abundance analysis of four giants in NGC 6553

Metal-rich globular clusters trace the formation of bulges. Abundance ratios in the metal-rich globular clusters such as NGC 6553 can constrain the formation timescale of the Galactic bulge. The purpose of this study is determine the metallicity and elemental ratios in individual stars of the metal-rich bulge globular cluster NGC 6553. A detailed abundance analysis of four giants in NGC 6553 is carried out, based on optical high-resolution echelle spectra obtained with UVES at the ESO VLT-UT2 Kueyen telescope. A metallicity [Fe/H]= -0.20 dex is derived, together with $\alpha$-element enhancement of Mg and Si ([Mg/Fe]=+0.28, [Si/Fe]=+0.21), solar Ca and Ti ([Ca/Fe]=+0.05, [Ti/Fe]=-0.01), and a mild enhancement of the r-process element Eu with [Eu/Fe] = +0.10. A mean heliocentric radial velocity of -1.86 km s$^{-1}$ is measured. We compare our results with previous investigations of the cluster.Comment: 15 pages, 8 figures, A&A, in pres

Synthesis and properties of ZnTe and ZnTe/ZnS core/shell semiconductor nanocrystals

Nanocrystals obtained by growing a protecting ZnS shell onto a photoactive ZnTe core afford nanocrystals that can represent alternatives to cadmium-based quantum dots

The State of Organic Seed in Europe

This booklet aims at supporting the expansion, both horizontal and vertical, of the European market for organic seed. Organic farmers need seed bred specifically to withstand the local and environmental conditions without the use of external, synthetic inputs. The size of the demand, however, does not justify the investment needed, when left entirely to market forces. This booklet estimates the potential market for organic seed in the EU and any challenges to its full development, and particularly the role played by the current derogation process for use of conventional untreated seed. Also analysed is the lack and inconsistency of information for farmers on what is available and how it meets their needs. In particular, the study compares and identifies gaps in the use of national databases and annual reports on derogations across Europe, and how these can be modified to provide stronger policy incentives to the market. Suppliers were interviewed on technical and economic challenges to seed production and farmers were involved in discussions on how organic seed is acquired and used

The State of Organic Seed in Europe

This booklet aims at supporting the expansion, both horizontal and vertical, of the European market for organic seed. Organic farmers need seed bred specifically to withstand the local and environmental conditions without the use of external, synthetic inputs. The size of the demand, however, does not justify the investment needed, when left entirely to market forces. This booklet estimates the potential market for organic seed in the EU and any challenges to its full development, and particularly the role played by the current derogation process for use of conventional untreated seed. Also analysed is the lack and inconsistency of information for farmers on what is available and how it meets their needs. In particular, the study compares and identifies gaps in the use of national databases and annual reports on derogations across Europe, and how these can be modified to provide stronger policy incentives to the market. Suppliers were interviewed on technical and economic challenges to seed production and farmers were involved in discussions on how organic seed is acquired and used

Enhanced coupling between massive fermions and zone-boundary phonons probed by infrared resonance Raman in bilayer graphene

Few-layer graphene possesses low-energy carriers which behave as massive fermions, exhibiting intriguing properties in both transport and light scattering experiments. By lowering the excitation energy of resonance Raman spectroscopy down to 1.17 eV we target these massive quasiparticles in the low-energy split bands close to the K point. The low excitation energy suppresses some of the Raman processes which are resonant in the visible, and induces a clearer frequency-separation of the sub-structures of the resonant 2D peak. Studying the different intensities of the sub-structures and comparing experimental measurements with fully ab initio theoretical calculations, in the case of bilayer graphene we unveil an enhanced coupling between the massive fermions and the lattice vibrations at the K point, in analogy to what found for the massless fermions of monolayer graphene, and also suggesting that what governs the enhancement is the vicinity of the electron-hole pair momentum to K rather than how small the electron-hole pair energy is.Comment: 14 pages, 10 figure