Search results for "table"
showing 10 items of 2807 documents
Character Tables and Sylow Subgroups Revisited
2018
Suppose that G is a finite group. A classical and difficult problem is to determine how much the character table knows about the local structure of G and vice versa.
Halogen and hydrogen bonds in compressed pentachloroethane
2016
In pentachloroethane, C2HCl5, high pressure initially strongly compresses the C–H⋯Cl bonds in phase I; however, in phase II which is stable above 0.62 GPa the role of hydrogen bonds is diminished and molecular aggregation is dominated by halogen bonds Cl⋯Cl. Both phases have been determined by X-ray diffraction and the phase diagram of C2HCl5 has been outlined. The transition between phases I and II retains some relation between their structures and reduces the symmetry from class mmm (space group Pnma) to 2/m (space group P21/n11). The discontinuous transition, with the shear strain exceeding 21°, is so strong that its progress can be visually observed even for powdered samples. The single…
The use of simulation methods to obtain the structure and conformation of 10-cyano-9,9′-bianthryl by electron diffraction and high-resolution imaging
1995
Abstract Experimental electron diffraction patterns and high-resolution images were used to determine the space group and unit cell dimensions of 10-cyano-9,9′-bianthryl. Subsequently the molecular conformation was calculated by semi-empirical quantum-mechanical methods. The molecule was then placed with the appropriate symmetry into the unit cell and the conformational as well as the packing energy deduced by an iterative procedure until good agreement was obtained between experiment and theory.
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.
Ab Initio Structure Determination of Vaterite by Automated Electron Diffraction
2012
tion that is fundamental for understanding material properties. Still, a number of compounds have eluded such kinds of analysis because they are nanocrystalline, highly disordered, with strong pseudosymmetries or available only in small amounts in polyphasic or polymorphic systems. These materials are crystallographically intractable with conventional Xray or synchrotron radiation diffraction techniques. Single nanoparticles can be visualized by high-resolution transmission electron microscopy (HR-TEM) up to sub�ngstrom resolution, [2] but obtaining 3D information is still a difficult task, especially for highly beam-sensitive materials and crystal structures with long cell parameters. Elec…
Testing a theoretical resistance law for overland flow under simulated rainfall with different types of vegetation
2020
Abstract In this paper a recently theoretically deduced flow resistance equation, based on a power-velocity profile, was tested using data collected for overland flow under simulated rainfall carried out in plots with vegetation. The available data were obtained exploring a wide range of rainfall intensities (from 60 to 181 mm h−1) and slopes (from 3.6 to 39.6%), and with four different types of vegetation. The database, including measurements of flow velocity, water depth, cross sectional flow area, wetted perimeter and bed slope, was divided in four datasets (one for each vegetation type), which allowed the calibration of the relationship between the velocity profile parameter Γ, the slop…
118 and Counting … The Periodic Table on its 150th Anniversary.
2019
"Is there still room for more elements in the modern periodic table with its currently 118 elements? Will we need another extra series in the periodic table besides the classical s-, p-, and d-block, and the lanthanides/actinides? Will the periodic table in this region still feature periodicity? …" Read more in the Guest Editorial by C. E. Dullmann.
On complete set of solutions for polynomial matrix equations
1990
Abstract In this paper we introduce the concept of co-solution of a polynomial matrix equation which permits us to obtain necessary and sufficient conditions so that a set of solutions be a complete set.
Infinite games and chain conditions
2015
We apply the theory of infinite two-person games to two well-known problems in topology: Suslin's Problem and Arhangel'skii's problem on $G_\delta$ covers of compact spaces. More specifically, we prove results of which the following two are special cases: 1) every linearly ordered topological space satisfying the game-theoretic version of the countable chain condition is separable and 2) in every compact space satisfying the game-theoretic version of the weak Lindel\"of property, every cover by $G_\delta$ sets has a continuum-sized subcollection whose union is $G_\delta$-dense.
A Brauer-Wielandt formula (with an application to character tables)
2016
If a p p -group P P acts coprimely on a finite group G G , we give a Brauer-Wielandt formula to count the number of fixed points | C G ( P ) | | \textbf {C}_{G}(P) | of P P in G G . This serves to determine the number of Sylow p p -subgroups of certain finite groups from their character tables.