The temperature dependence (10 − 290 K) of the low-frequency (20 − 150 cm −1 ) Raman-active phonon modes of supercooled confined water in L,L-diphenylalanine micro/nanotubes was analysed. The isolated dynamics of a specific geometry of water cluster (pentamer) in supercooled confined regime was studied in detail. A particular mode concerning water-nanotube interaction was also probed. A fragile-to-strong transition at 204 K was observed and related to the crossing of the Widom line. The critical exponent analyses of the relaxation rate data based on mode-coupling theory indicated perfect agreement among experimental data and theory. Our results are consistent with the existence of a second critical point of water.The distinction between gas and liquid disappears above its critical point. At pressure and temperature above this point, the system is said to be in a fluid state (supercritical fluid) [1]. Supercritical fluids are recognized as possessing unique solvation properties that make them important technological materials [1]. Of particular interest is the behavior of water in confined spaces since it plays a key role in protein hydration since nanoscale fluctuations associated with the so-called Widom line can influence biological processes [2,3].Poole et al.[4] presented a thermodynamically consistent molecular dynamical simulation study view regarding the global phase behavior of supercooled water. According to these authors, in the supercooled region just below the line of homogeneous ice nucleation, a critical point of liquid-liquid coexistence (LLCP) could exist that would eliminate the first-order transition line between low-density liquid (LDL) and high-density liquid (HDL) aqueous phases. Thus, liquid-liquid phase separation and the existence of the LLCP in water remains as a plausible hypothesis and requires further verification [5]. The Widom line temperature T W corresponds to the loci of maxima of thermodynamic response function in the one-phase region beyond the LLCP proposed to exist in supercooled liquid water [4].Molecular dynamics simulations of the TIP4P/2005 model of water performed by Kumar et al. [6] indicated that the onset of the Boson peak in supercooled bulk water coincides with the crossover to a predominantly LDL-like below T W . Gallo, Corradini and Roveri [7] studied the dynamical properties of aqueous solution of NaCl upon supercooling by molecular simulations. They found a crossover from a fragile (super-Arrhenius) to a strong (Arrhenius) behavior upon crossing the T W by both ionic solution and bulk water.Experiments in the supercooling region are extremely difficult due to crystal nucleation processes. Thus exper- * herculano.martinho@ufabc.edu.br imental pieces of evidence concerning the different hypotheses supporting the existence of LLCP are hard to test [8].In confinement water can be more easily supercooled and studied in region of phase space where crystallization of bulk water cannot be avoided. Confined water in nanoporous silica have been extensively studied [9][10]...

Synthesis of RNiO 3 (R=rare earth) nanowires can be interesting as building blocks with potential applications in optoelectronic devices. Here, we describe the synthesis and characterization of NdNiO 3-δ (NNO) nanowires produced by electrospinning technique via polymeric precursor solution at relatively low temperature and oxygen pressure. These NNO nanowires were characterized by x-ray diffraction (XRD), x-ray photodetection spectroscopy (XPS), Field Emission Scanning Electron Microscopy (Fe-SEM), Magnetization (M(T)) and electrical resistance (R(T)) measurements. SEM images revealed a granular nanowire microstructure of NNO nanostructures, with a distribution of nanowire diameters ranging from 50 to 150 nm. The NNO nanowires also exhibit granular characteristics with an average grain diameter of 40 nm. The x-ray diffraction patterns of the NNO nanowires indicated that these samples exhibited a high degree of crystallinity and their Bragg reflections can be indexed to an orthorhombic-distorted (Pbnm symmetry) perovskite structure. The crystalline structure seems to be slightly texturized in some Bragg directions and with a slightly strained crystallite. M(T) and R(T) measurement as a function of temperature curves show that these NNO samples present a metal-insulator (MI) transition close to T MI ∼198 K, which is usually observed in NNO thin films and bulk samples. The nanostructured shape and these experimental observations can be promising in designing new electronic devices using this strongly correlated oxide.