Search results for " confined water"
showing 4 items of 4 documents
Hysteresis in the temperature dependence of the IR bending vibration of deeply cooled confined water.
2019
Using Fourier Transform Infrared (FTIR) spectroscopy, we investigate the temperature dependence of the bending vibrations of water confined in the pores of a silica hydrogel in the temperature interval of 270-180 K. We also investigate the presence of thermal hysteresis by cooling and reheating temperature scans. The results clearly show the presence, at about 230 K, of a crossover in the temperature dependence of the IR spectra; moreover, the presence of hysteresis is clearly demonstrated. By comparing FTIR data with neutron diffraction data and previous calorimetric data on the same samples, we conclude that the crossover and the hysteretical behavior do not involve a water glass transiti…
Kinetic energy and radial momentum distribution of hydrogen and oxygen atoms of water confined in silica hydrogel in the temperature interval 170–325…
2019
Water is an ubiquitous liquid and it is necessary for life;. Studies on water are therefore of obvious scientific and .... technological relevance. In view of its peculiar physicalproperties (the so-called water anomalies, particularly relevant at low temperatures [1]), studies on water structureand dynamics in ample temperature intervals, covering also the supercooling region, have attracted much interest in recent years. In particular, studies focused on the supercooled phase are important in order to test theories and hypotheses[2,3], including the liquid-liquid phase transition hypothesis [4-6] and the related fragile-to-strong crossover observed inwater confined in silica matrices and …
THE PHYSICAL ORIGIN OF PROTEIN DYNAMICAL TRANSITION: A LIQUID-LIQUID TRANSITION IN HYDRATION WATER?
2015
In this thesis I study, by means of neutron scattering, calorimetry, and dielectric spectroscopy, the physical origin of protein dynamical transition (PDT) which is usually observed at ~230 K in protein hydrated powders and is deemed necessary for protein function. Measurements reported in this thesis have been performed on hydrated powders of Myoglobin. The combined use of different experimental techniques gives a coherent description of the PDT and reveals a connection with a liquid-liquid crossover occurring in the protein hydration water at about the same temperature. In order to deepen our understanding of this connection and to obtain a direct experimental evidence of the existence of…
Application of Broadband Dielectric Spectroscopy to Cultural Heritage: characterization and preservation of ancient paper artwork
2016
Within the cultural heritage the characterization and conservation of artworks based on paper represents a significant issue for both restorers and scientists. The paper deterioration is affected by the degree of hydrolytic and oxidative reactions which occur upon aging. Moreover, the durability of cellulose fibers depends on the intrinsic composition/structure of the paper as well as on the conservation conditions, such as temperature and humidity. The structural and dynamical characterization of the cellulose matrix and of the water confined within its pores is therefore of central interest. Our working hypothesis is that WATER DYNAMICS is one of the main determinants of paper degradation…