101,075 research outputs found
Limits of metastability in amorphous ices: <sup>2</sup>H-NMR relaxation
No full textThe high-frequency reorientation dynamics of O-H-2 bonds is investigated in various amorphous ices including eHDA (expanded high density amorphous ice), LDA-II (low density amorphous ice II) and HGW (hyperquenched glassy water) using H-2-NMR spin-lattice relaxation as a local probe. Both low density forms, HGW and LDA-II, show similar spin-lattice relaxation but differ in the thermal stability with respect to the transition into crystalline cubic ice I-c. HGW already transforms slightly above 135 K whereas LDA-II crystallizes at 150 K. eHDA is distinguishable from other high density amorphous ices in its thermal stability and spin-lattice relaxation. Its relaxation times are much larger compared to those of VHDA (very high density amorphous ice) and uHDA (unrelaxed high density amorphous ice). eHDA does not show annealing effects, transforms sharply into LDA-II above 123 K and provides higher thermal stability as compared to other high density forms.Austrian Science Fund [T463, Y391]; European Research Counci
Pressure-annealed high-density amorphous ice made from vitrified water droplets: A systematic calorimetry study on water's second glass transition
No full textIn previous work, water’s second glass transition was investigated based on an amorphous sample made from crystalline ice [Amann-Winkel et al., Proc. Natl. Acad. Sci. U. S. A. 110, 17720 (2013)]. In the present work, we investigate water’s second glass transition based on the genuine glassy state of high-density water as prepared from micron-sized liquid water droplets, avoiding crystallinity at all stages. All the calorimetric features of water’s second glass transition observed in the previous work are also observed here on the genuine glassy samples. This suggests that the glass transition indeed thermodynamically links amorphous ices continuously with deeply supercooled water. We proceed to extend the earlier study by investigating the effect of preparation history on the calorimetric glass transition temperature. The best samples prepared here feature both a lower glass transition temperature Tg,2 and a higher polyamorphic transition temperature Tons, thereby extending the range of thermal stability in which the deeply supercooled liquid can be observed by about 4 K. Just before the polyamorphic transition, we observe a spike-like increase of heat capacity that we interpret in terms of nucleation of low-density water. Without this spike, the width of water’s second glass transition is 15 K, and the Δcp amounts to 3 ± 1 J K−1 mol−1, making the case for the high-density liquid being a strong liquid. We suggest that samples annealed at 1.9 GPa to 175 K and decompressed at 140 K to ≥0.10 GPa are free from such nuclei and represent the most ideal high-density amorphous glasses.Version of recor
Joshua Davis: Author of Spare Parts
No full textCitation: K-State First (2016). Joshua Davis: Author of Spare Parts [Flier]. Manhattan, Kansas: K-State First.Flyer advertising Joshua Davis's author talk at Kansas State University
Lynn Townsend White, J. K., Latin mcmasticism in Norman Sicily, 1938
No full textAmann E. Lynn Townsend White, J. K., Latin mcmasticism in Norman Sicily, 1938. In: Revue des Sciences Religieuses, tome 19, fascicule 1, 1939. pp. 147-148
X-ray Scattering and O-O Pair-Distribution Functions of Amorphous Ices
No full textThe structure factor and oxygen-oxygen pair-distribution functions of amorphous ices at liquid nitrogen temperature (T = 77 K) have been derived from wide-angle X-ray scattering (WAXS) up to interatomic distances of r = 23 Å, where local structure differences between the amorphous ices can be seen for the entire range. The distances to the first coordination shell for low-, high-, and very-high-density amorphous ice (LDA, HDA, VHDA) were determined to be 2.75, 2.78, and 2.80 Å, respectively, with high accuracy due to measurements up to a large momentum transfer of 23 Å-1. Similarities in pair-distribution functions between LDA and supercooled water at 254.1 K, HDA and liquid water at 365.9 K, and VHDA and high-pressure liquid water were found up to around 8 Å, but beyond that at longer distances, the similarities were lost. In addition, the structure of the high-density amorphous ices was compared to high-pressure crystalline ices IV, IX, and XII, and conclusions were drawn about the local ordering
Colloquium: Water's controversial glass transitions
No full textWater is the most common and, judged from its numerous anomalous properties, the weirdest of all known liquids and the complexity of its pressure-temperature map is unsurpassed. A major obstacle on the way to a full understanding of water's structure and dynamics is the hard-to-explore territory within this map, colloquially named the no man's land. Many experiments suggest that just before stepping across its low-temperature border, amorphous ices undergo glass-to-liquid transitions while other interpretations emphasize the importance of underlying disordered (nano) crystalline states. Prospects for reconciling the conflicting views regarding the nature of water's glass transitions are discussed
Ultra-slow dynamics in low density amorphous ice revealed by deuteron NMR: indication of a glass transition
No full textThe postulated glass-liquid transition of low density amorphous ice (LDA) is investigated with deuteron NMR stimulated echo experiments. Such experiments give access to ultra-slow reorientations of water molecules on time scales expected for structural relaxation of glass formers close to the glass-liquid transition temperature. An involved data analysis is necessary to account for signal contributions originating from a gradual crystallization to cubic ice. Even if some ambiguities remain, our findings support the view that pressure amorphized LDA ices are of glassy nature and undergo a glass-liquid transition before crystallization
K. Bihlmeyer, Kirchengeschichte, auf Grund des Lehrbuches von T. X. von Funk. II. Teil : Das Mittelalter, 1930
No full textAmann E. K. Bihlmeyer, Kirchengeschichte, auf Grund des Lehrbuches von T. X. von Funk. II. Teil : Das Mittelalter, 1930. In: Revue des Sciences Religieuses, tome 12, fascicule 1, 1932. pp. 139-140
Steven Johnson Author Talk Poster
No full textK-State Book NetworkA poster advertising an author talk by Steven Johnson at Kansas State University on September 3, 2014. Steven Johnson's book "The Ghost Map" was the 2014-2015 common book
99-Air-Balloons - A Comment on Schimank, Uwe "Call to Revitalize the Institutionalist Paradigm of the Sociology of Science" (ZfS-1/1995)
No full textAmann K. "99 Luftballons" (Nena). Eine Antwort auf Uwe Schimanks "Für eine Erneuerung der institutionalistischen Wissenschaftssoziologie" (ZfS 1/1995). Zeitschrift für Soziologie. 1995;24(2):156-159
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