Effect of vine vigour of Vitis vinifera cv. Nebbiolo clones on wine acidity and quality

The grapevine cv. Nebbiolo grown in northern Italy produces high-quality red wines, of which Barolo and Barbaresco are the best known. During a clonal selection project, clones of this variety were assessed for their agronomical and enological value. Different degrees of vegetative vigour were found among them, and this was related to modifications of must and wine composition, with particular respect to the acidity. Over 4 years of observations, vigorous clones produced musts and wines of higher pH, regardless of the amount of titratable acidity. This was associated with a higher malic acid content in the juice and with a higher concentration of potassium in the wine. In addition, wines from vigorous clones showed an unbalanced ratio of colour components. They ranked at the lowest score in the sensory evaluation tests

Tc=21K in epitaxial FeSe0.5Te0.5 thin films with biaxial compressive strain

High purity epitaxial FeSe0.5Te0.5 thin films with different thickness were grown by Pulsed Laser Ablation on different substrates. By varying the film thickness, Tc up to 21K were observed, significantly larger than the bulk value. Structural analyses indicated that the a axis changes significantly with the film thickness and is linearly related to the Tc. The latter result indicates the important role of the compressive strain in enhancing Tc. Tc is also related to both the Fe-(Se,Te) bond length and angle, suggesting the possibility of further enhancement

Temperature- and doping-dependent nanoscale Schottky barrier height at the Au/Nb:SrTiO3interface

We use ballistic electron emission microscopy to investigate prototypical Au/Nb-doped SrTiO3(NSTO) Schottky barrier diodes for different temperatures and doping levels. To this end, ultrathin Au overlayers are thermally evaporated onto TiO2-terminated NSTO single crystal substrates. We show that at room temperature, regardless of the nominal doping, rectification is controlled by a spatially inhomogeneous Schottky barrier height (SBH), which varies on a length scale of tens of nanometers according to a Gaussian distribution with a mean value of 1.29-1.34 eV and the standard deviation in the range of 80-100 meV. At lower temperatures, however, doping effects become relevant. In particular, junctions with a low Nb content of 0.01 and 0.05 wt. % show an 3c300 meV decrease in the mean SBH from room temperature to 80 K, which can be explained by an electrostatic analysis assuming a temperature-dependent dielectric permittivity for NSTO. In contrast, this model fails to predict the weaker temperature dependence of SBH for junctions based on 0.5 wt. % NSTO. Our nanoscale investigation demands to reassess conventional models for the NSTO polarizability in high-intensity electric fields. Furthermore, it contributes to the comprehension and prediction of transport in metal/SrTiO3junctions and devices

William R. Brinkley:A giant in biomedical research and public policy

Susan A. Gerbi, Robert E. Palazzo, William C. Earnshaw, and William T. Schrader discuss the life and achievements of William R. Brinkley, who passed away on November 10, 2020

The surface layer of Sr2_2RuO4_4: A two-dimensional model system for magnetic-field-tuned quantum criticality

Many of the exciting properties of strongly correlated materials are intricately linked to quantum critical points in their phase diagram. This includes phenomena such as high temperature superconductivity, unconventional superconductivity in heavy fermion materials, as well as exotic nematic states in Sr$_3$Ru$_2$O$_7$. One of the experimentally most successful pathways to reaching a quantum critical point is tuning by magnetic field allowing studies under well-controlled conditions on ultra-clean samples. Yet, spectroscopic evidence of how the electronic states change across a field-tuned quantum phase transition, and what the importance of quantum fluctuations is, is not available so far. Here we show that the surface layer of Sr$_2$RuO$_4$ is an ideal two-dimensional model system for a field-tuned quantum phase transition. We establish the existence of four van Hove singularities in close proximity to the Fermi energy, linked intricately to checkerboard charge order and nematicity of the electronic states. Through magnetic field, we can tune the energy of one of the van Hove singularities, with the Lifshitz transition extrapolated at ~32T. Our experiments open up the ability to directly study spectroscopically the role of quantum fluctuations at a field-tuned quantum phase transition in an effectively 2D strongly correlated electron material. Our results further have implications for what the leading instability in Sr$_2$RuO$_4$ is, and hence for understanding the enigmatic superconductivity in this material.Comment: 31 pages, 4 figure