Search results for " transitions"
showing 10 items of 196 documents
Colloidal layers in magnetic fields and under shear flow
2005
The behaviour of colloidal mono- and bilayers in external magnetic fields and under shear is discussed and recent progress is summarized. Superparamagnetic colloidal particles form monolayers when they are confined to a air–water interface in a hanging water droplet. An external magnetic field allows us to tune the strength of the mutual dipole–dipole interaction between the colloids and the anisotropy of the interaction can be controlled by the tilt angle of the magnetic field relative to the surface normal of the air–water interface. For sufficiently large magnetic field strength crystalline monolayers are found. The role of fluctuations in these two-dimensional crystals is discussed. Fur…
The impact of COVID-19 on alternative and local food systems and the potential for the sustainability transition: Insights from 13 countries
2021
The COVID-19 pandemic has been a major stress test for the agri-food system. While most research has analysed the impact of the pandemic on mainstream food systems, this article examines how alternative and local food systems (ALFS) in 13 countries responded in the first months of the crisis. Using primary and secondary data and combining the Multi-Level Perspective with social innovation approaches, we highlight the innovations and adaptations that emerged in ALFS, and how these changes have created or supported the sustainability transition in production and consumption systems. In particular, we show how the combination of social and technological innovation, greater citizen involvement,…
Understanding the effects of Covid-19 through a life course lens
2020
Available online 22 July 2020. Other co-authors: ANTONUCCI, T. C., DYKSTRA, P. A., HECKHAUSEN, J., KUH, D., MAYER, K. U., MOEN, P., MORTIMER, J. T., MULDER, C. H., SMEEDING, T. M., VAN DER LIPPE, T., HAGESTAD, G. O., KOHLI, Martin, LEVY, R., SCHOON, I., & THOMSON, E. The Covid-19 pandemic is shaking fundamental assumptions about the human life course in societies around the world. In this essay, we draw on our collective expertise to illustrate how a life course perspective can make critical contributions to understanding the pandemic’s effects on individuals, families, and populations. We explore the pandemic’s implications for the organization and experience of life transitions and trajec…
Quadrupole deformation of Xe-130 measured in a Coulomb-excitation experiment
2020
Physical review / C 102(5), 054304 (2020). doi:10.1103/PhysRevC.102.054304
In situ characterization of the high pressure – high temperature melting curve of platinum
2019
AbstractIn this work, the melting line of platinum has been characterized both experimentally, using synchrotron X-ray diffraction in laser-heated diamond-anvil cells, and theoretically, using ab initio simulations. In the investigated pressure and temperature range (pressure between 10 GPa and 110 GPa and temperature between 300 K and 4800 K), only the face-centered cubic phase of platinum has been observed. The melting points obtained with the two techniques are in good agreement. Furthermore, the obtained results agree and considerably extend the melting line previously obtained in large-volume devices and in one laser-heated diamond-anvil cells experiment, in which the speckle method wa…
Structural and vibrational behavior of cubic Cu1.80(3)Se cuprous selenide, berzelianite, under compression
2020
[EN] We have performed an experimental study of the crystal structure and lattice dynamics of cubic Cu1.80(3)Se at ambient temperature and high pressures. Two reversible phase transitions were found at 2.9 and 8.7 GPa. The indexation of the angle-dispersive synchrotron x-ray diffraction patterns suggests a large orthorhombic cell and a monoclinic cell for the high-pressure phases. Raman measurements provide additional information on the local structure. The compressibility of the three ambient temperature phases has been determined and compared to that of other sulphides and selenides.
High-pressure/high-temperature phase diagram of zinc
2018
The phase diagram of zinc (Zn) has been explored up to 140 GPa and 6000K, by combining optical observations, x-ray diffraction, and ab initio calculations. In the pressure range covered by this study, Zn is found to retain a hexagonal close-packed (hcp) crystal symmetry up to the melting temperature. The known decrease of the axial ratio (c/a) of the hcp phase of Zn under compression is observed in x-ray diffraction experiments from 300K up to the melting temperature. The pressure at which c/a reaches root 3 (approximate to 10GPa) is slightly affected by temperature. When this axial ratio is reached, we observed that single crystals of Zn, formed at high temperature, break into multiple pol…
High-pressure theoretical and experimental study of HgWO4
2011
HgWO 4 at ambient pressure is characterized using a combination of ab initio calculations, X-ray diffraction and Raman scattering measurements. The effect of low pressure and temperature on the structural stability is analysed. Extending our ab initio study to the range of higher pressures, a sequence of stable phases up to 30GPa is proposed. © 2011 Taylor & Francis.
Geovisualizing the sail-to-steam transition through vessel movement data
2017
International audience; Technological transitions in the maritime and port industries go along with increased transport and economic efficiency, resulting in faster movements and longer travelled distances. Yet, such transformations may also enhance disparities between winners and loosers, should they be ports or shipping companies. This research focuses on the particular case of the transition from sail to steam over the period 1890-1925, which witnesses the rapid replacement of sailing vessels, the latter concentrating 65% of the world fleet in 1890 but only 3.5% in 1925. It applies a variety of measures to compare how these two layers overlap in the network (at links and ports) and what …
Comparative study of the high-pressure behavior of ZnV2O6, Zn2V2O7, and Zn3V2O8
2020
We report a study of the high-pressure structural behavior of ZnV2O6, Zn2V2O2, and Zn3V2O8, which has been explored by means of synchrotron powder x-ray diffraction. We found that ZnV2O6 and Zn3V2O8 remain in the ambient-pressure structure up to 15 GPa. In contrast, in the same pressure range, Zn2V2O2 undergoes three phase transitions at 0.7, 3.0, and 10.8 GPa, respectively. Possible crystal structures for the first and second high-pressure phases are proposed. Reasons for the distinctive behavior of Zn2V2O2 are discussed. The compressibility of the different polymorphs has been determined. The response to pressure is found to be anisotropic in all the considered compounds and the room-temp…