Chains of Metallic Clusters With Ligands

2021 ◽  
pp. 96-119
Keyword(s):  
Geometric Approach ◽  
Higher Dimension ◽  
Metallic Clusters ◽  
The Core ◽  
Metal Atoms ◽  
Dimension Space ◽  
Metal Chain ◽  
Valence Bonds

This chapter geometrically investigated the structure of clusters, the core of which represent the metal chains (linear or curved) of both identical and different elements. It was shown that the dimension of the structures of these clusters is more than three. To create a model of these chains in a higher dimension space, a new geometric approach has been developed that allows us to construct convex, closed polytopes of these chains. It consists of removing part of the octahedron edges necessary for constructing the octahedron and adding the same number of new edges necessary to build a closed polytope chain while maintaining the number of metal atoms and ligands and their valence bonds. As a result, it was found that metal chain polytopes consist of polytopes of higher dimension, adjacent to each other along flat sections.

Clusters of Chemical Compounds as Polytopes of the Highest Dimension

2021 ◽  
pp. 27-51
Keyword(s):  
Metal Atom ◽  
High Dimension ◽  
Copper Cluster ◽  
Higher Dimension ◽  
The Core ◽  
Metal Atoms ◽  
Common Center ◽  
A Chain ◽  
Analytical Expressions ◽  
Flat Section

General analytical expressions are obtained for calculating the dimension of multi-shell clusters with a common center of shells in those cases when there is a metal atom in the center of the shells and when it is not. The shells can be in the shape of any body of Plato. It has been established that the gamma-copper cluster has the form of a cross-polytope of high dimension. The forms of clusters with ligands of the core of which is a chain of metal atoms or a metal polyhedron are geometrically investigated. It is shown that if the skeleton is a chain of metal atoms, then the cluster is polytope composed of two polytopes of higher dimension adjacent to each other along a flat section containing a chain. If the skeleton is a metal polyhedron, then a cluster of higher dimension has several ligand shells.

scholarly journals Crystal Prediction using the Point Groups: an Application of Group Theory

2014 ◽  
Vol 70 (a1) ◽  
pp. C1427-C1427
Author(s):  
Gregory McColm
Keyword(s):  
Group Theory ◽  
Geometric Approach ◽  
Geometric Object ◽  
Topological Equivalence ◽  
Breadth First Search ◽  
Matrix Representations ◽  
The Core ◽  
Point Groups ◽  
Crystal Design ◽  
Crystal Net

As a blueprint for designing a crystal, a crystal net should be a geometric object. So a crystal design regime might be based on an algorithm that generates crystal nets using geometry. The "Crystal Turtlebug" is such a program, generating crystal nets as graphs embedded in 3-space. McColm et al (2011) described a "Maple" version; it generated crystal nets of one or two kinds of vertices and one or two kinds of edges. A new "Python" version can generate crystal nets of any number of kinds of vertices and edges. The algorithm employs matrix representations of point groups. The "core" of the program takes a fragment of the prospective crystal (e.g. for a crystal of 3 kinds of atoms and 2 kinds of bonds, a "transversal" of 3 vertices and 2 edges). The core assigns point groups to the vertices and isometries to the edges. The core then repeatedly applies groups to isometries and vice versa to generate a unit cell. The computational problem is finding a transversal that produces a chemically plausible crystal net, as most crystal nets found are implausible. We follow a breadth-first search and enumerate some transversals, screen them, generate crystal nets from the screened transversals, and screen the results. This process can entail generating millions of transversals to obtain a handful of crystal nets for users to view manually. Although such a geometric approach is somewhat different from the more popular directions of contemporary research in crystal prediction, there is precedent in the work of A. F. Wells, A. Le Bail, C. Wilmer et al, and in particular M. Treacy et al (2004). In principle, the Crystal Turtlebug will generate every crystal net up to topological equivalence. In practice, there is an exponential explosion in the number of transversals, so the time spent enumerating crystal nets within fixed parameters explodes exponentially with the number of kinds of atoms and bonds (McColm (2012)).

The Core of Logics

2017 ◽  
pp. 1-72
Author(s):  
Jeremy Horne
Keyword(s):  
Pattern Recognition ◽  
Three Dimensional ◽  
Functional Completeness ◽  
Research Directions ◽  
Binary Structure ◽  
The Core ◽  
Fundamental Law ◽  
Dimension Space ◽  
The Relationship ◽  
The Universe

Like mathematics so often logic is taught to introductory students in a very mechanical way, the emphasis being on memorization and working problems. Particularly egregious is that the logic taught in philosophy departments is devoid of philosophy. Students rarely encounter the deep philosophy underpinning the structures. Logic is the theory of innate order in the universe and is the language of that order. More explicitly the foundation of that order is binary, based on the most fundamental law of all: dialectics. Something is apprehended because of what it is not. This chapter summarizes the development of thinking underpinning this idea of the innate binary structure. It is an ordered binary space starting in one dimension and progressing through three, and beyond. The philosophical basis of single, two (Table of Functional Completeness), and three (three-dimensional hypercube) dimension space provides coherency to ideas like deduction, induction, and inference, in general. The ordering in these spaces is founded on the same thinking giving rise to numbers and arithmetic. An exposition of how binary logical space develops sets the stage for discussing foundational ideas like the relationship between arithmetic (and its follow-on, mathematics) and logic, pattern recognition, and even whether we may be a simulation, a conjector made by Nick Bostrom. Research directions are proposed such as questioning the nature of axioms, exploring the insufficiency of Peano's postulates, proof theory, and ordering of operators based on intellectual complexity.

scholarly journals Oxovanadium(IV)-sulfite compounds: Synthesis and structural and physical studies

2005 ◽  
Vol 77 (9) ◽  
pp. 1529-1538 ◽  
Author(s):  
George I. Chilas ◽  
Haralampos N. Miras ◽  
Manolis J. Manos ◽  
J. Derek Woollins ◽  
Alexandra M. Z. Slawin ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Cyclic Voltammetric ◽  
Acidic Aqueous Solution ◽  
X Ray ◽  
Open Framework ◽  
Mild Conditions ◽  
The Core ◽  
Metal Atoms ◽  
Framework Species ◽  
Ph Range

Reaction of VIVOCl2 in strongly acidic aqueous solution with either (NH4)2SO3 or Na2SO3 and Bu4NBr at ~70°C in the pH range 2.5-4.5 gives the clusters (NH4)2{[V4IV(μ4-O)2(μ3-OH)2](VIVO)2(μ3-SO3)4O4(H2O)2} and (n-Bu4N)2{[V4IV(μ4-O)2(μ3-OH)2](VIVO)2(μ3-SO3)4O4(H2O)2}, respectively. Reaction of NH4VVO3 with (NH4)2SO3 resulted in the isolation of the first compound. When the latter reaction is carried out in the presence of MgO, compound (NH4)[VIVO(SO3)1.5H2O]∞.2.5H2O was isolated instead. Compound (n-Bu4N)2{[V4IV(μ4-O)2(μ3-OH)2](VIVO)2(μ3-SO3)4O4(H2O)2} and (NH4)[VIVO(SO3)1.5H2O]∞.2.5H2O were characterized by X-ray structure analysis. The crystal structure of species (n-Bu4N)2{[V4IV(μ4-O)2(μ3-OH)2](VIVO)2(μ3-SO3)4O4(H2O)2} revealed a unprecedented hexanuclear cluster consisting of a cubane core [M4(μ4-O)2(μ3-OH)2] connected to two other metal atoms through the core oxo-groups and four μ3-SO3 bridges. Compound (NH4)[VIVO(SO3)1.5H2O]∞.2.5H2O represents a rare example of an open-framework species prepared under mild conditions. Cyclic voltammetric examination of compound (n-Bu4N)2{[V4IV(μ4-O)2(μ3-OH)2](VIVO)2(μ3-SO3)4O4(H2O)2} revealed a redox process which was assigned to the oxidation of one core of vanadium(IV) to vanadium(V).

A Photoelectron Spectroscopy Study of Ethylenedioxythiophene Adsorption on Polycrystalline Gold Surfaces

2000 ◽  
Vol 660 ◽  
Author(s):  
J. Birgerson ◽  
M. Keil ◽  
A. W. Denier van der Gon ◽  
X. Crispin ◽  
M. Lögdlund ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Thick Films ◽  
Gold Surface ◽  
Deposition Process ◽  
Binding Energies ◽  
Gold Surfaces ◽  
Copper Surfaces ◽  
The Core ◽  
Metal Atoms ◽  
Polycrystalline Gold

ABSTRACTThe interaction between thin films of ethylenedioxythiophene (EDOT) and polycrystalline copper and gold surfaces has been studied using photoelectron spectroscopy. Thick films of EDOT (∼100 Å) have been prepared by vapor deposition onto clean gold surfaces, which were cooled down to a temperature of 170 K during the deposition process. Monolayers were prepared by slowly heating the thick films up to 300 K. At 300 K most of the material has evaporated from the surface and about one monolayer remains chemisorbed on the gold surface. This shows that there is an interaction between EDOT and Au. This chemisorption causes a shift of around -0.5 eV of the binding energies for the core level electrons, presumably because of screening of the core-hole by the metal. An experimental and theoretical analysis of the valence level electrons suggests that two molecular orbitals, localized at the thiophene part of the molecule, are involved in the interaction with the metal atoms of the surface. The most likely orientation of the EDOT molecules is parallel to the Au surface. Upon adsorption the work function is changed from 5.2 eV for the clean gold surface to 4.0 eV for the EDOT monolayer. In the case of EDOT adsorbed on clean copper surfaces, no interaction was observed.

scholarly journals Optimized Polynomial Classifier for Classification of M-PSK Signals

2021 ◽  
Vol 8 (4) ◽  
pp. 575-582
Author(s):  
Nooh Bany Muhammad ◽  
Mubashar Sarfraz ◽  
Sajjad A. Ghauri ◽  
Saqib Masood
Keyword(s):  
Fading Channels ◽  
Additive White Gaussian Noise ◽  
Classification Problem ◽  
Research Area ◽  
Rician Fading ◽  
Computational Techniques ◽  
Modulation Classification ◽  
Higher Dimension ◽  
Polynomial Classifier ◽  
Dimension Space

Automatic modulation classification (AMC) is the emerging research area for military and civil applications. In this paper, M-PSK signals are classified using the optimized polynomial classifier. The distinct features i.e., higher order cumulants (HOC’s) are extracted from the noisy received signal and the dataset is generated with different number of samples, various SNR’s and on several fading channels. The proposed classifier structure classifies the overall modulation classification problem into binary sub-classifications. In each sub-classification, the extracted features are expanded using polynomial expansion into higher dimension space. In higher dimension space numerous non-linearly separable classes becomes linearly separable. The performance of the proposed classifier is evaluated on Rayleigh and Rician fading channels in the presence of additive white gaussian noise (AWGN). The polynomial classifier performance is optimized using one of the famous heuristic computational techniques i.e., Genetic Algorithm (GA). The extensive simulations have been carried with and without optimization, which shows relatively better percentage classification accuracy (PCA) as compared with the state of art existing techniques.

The Geometry of Higher-Dimensional Multi-Shell Clusters With Common Center and Different Centers

2019 ◽  
Vol 4 (2) ◽  
pp. 45-65
Author(s):  
Gennadiy Vladimirovich Zhizhin
Keyword(s):  
Structural Unit ◽  
Metal Clusters ◽  
Higher Dimension ◽  
Spatial Image ◽  
The Core ◽  
Palladium Cluster ◽  
Internal Geometry ◽  
Anion Cluster ◽  
Higher Dimensional ◽  
Common Center

In this article, it is shown that the dimension of a metal skeleton of giant palladium cluster, containing 561 atoms in five shells, is 8. The claims of some authors that the palladium cluster in this case is an E8 lattice are groundless. The internal geometry of multi-shell metal clusters with ligands and core was investigated. It is proved that the multi-shell clusters with common center and different centers have a higher dimension. Clusters with ligands and a structural unit octahedron exist with different metals in the core. A spatial image of the cobalt tetra-anion cluster is presented. It is proved that its dimension is 5. It is considered homo-element metal cycles with ligands. For example, a spatial image of the three nuclear carbonyls of ruthenium and osmium it is build. It was proved that the ligands in the three nuclear carbonyls of ruthenium and osmium do not form a ligand polyhedron, as was previously assumed. The construction of cluster in this case can be divided into two polytopes dimension of 4.

Carbidocarbonyl clusters of iron

1982 ◽  
Vol 308 (1501) ◽  
pp. 103-113 ◽  
Keyword(s):  
Carbon Atom ◽  
Elevated Temperatures ◽  
Chemical Shifts ◽  
Metal Carbonyls ◽  
Carbide Phases ◽  
The Core ◽  
Structural Resemblance ◽  
Metal Atoms ◽  
Reducing Conditions ◽  
Transition Metal Carbonyls

Under reducing conditions, at elevated temperatures, coordinated carbon monoxide in transition metal carbonyls may disproportionate to CO 2 and a carbon atom. The carbon atom is trapped in a cage of metal atoms, shielded from further reaction in the core of the resulting carbidocarbonyl clusters. This class of compounds, which has been known for some time, bears some structural resemblance to the binary carbides and may therefore be relevant to Fischer-Tropsch catalysis, in which carbide phases and surface carbon atoms are implicated. The chemical, structural and physical properties of the iron carbidocarbonyIs have been investigated. Reactions are described that lead to C-H and C-C bond formation at the carbide carbon, and these are discussed with regard to the nature of this carbon atom. 13 C n.m.r. spectroscopy reveals large downfield chemical shifts for the carbide carbon, which may be interpreted as either a reflexion of low electron density at the carbon or the influence of paramagnetic contributions to the shift. Reactions of [Fe 4 (CO) 12 C CO 2 CH 3 ]-, [Fe 4 (CO) 12 C C(O)CH 3 ]- and [Fe 4 (CO) 12 C CHO]- with trimethyloxonium fluoborate yield the corresponding vinylidene clusters Fe 4 (CO) 12 - C = C (OCH 3 )R (R = OCH 3 , CH 3 , H).

What face familiarity feelings say about the lateralization of specific entities within the core system

2019 ◽  
Vol 42 ◽  
Author(s):  
Guido Gainotti
Keyword(s):  
Temporal Lobe ◽  
Memory System ◽  
Core System ◽  
The Core ◽  
Memory Traces ◽  
Specific Memory ◽  
Target Article ◽  
Temporal Structures ◽  
The Right

Abstract The target article carefully describes the memory system, centered on the temporal lobe that builds specific memory traces. It does not, however, mention the laterality effects that exist within this system. This commentary briefly surveys evidence showing that clear asymmetries exist within the temporal lobe structures subserving the core system and that the right temporal structures mainly underpin face familiarity feelings.

A scanning electron microscopic study on dissolving process of cholesterol gallstones by chenodeoxycholic acid (CDCA)

1978 ◽  
Vol 36 (2) ◽  
pp. 522-523
Author(s):  
T. Kanetaka ◽  
M. Cho ◽  
S. Kawamura ◽  
T. Sado ◽  
K. Hara
Keyword(s):  
Electron Microscope ◽  
Chenodeoxycholic Acid ◽  
Outer Surface ◽  
Electron Microscopic ◽  
Cholesterol Gallstones ◽  
The Core ◽  
Scanning Electron Microscopic Study ◽  
Scanning Electron Microscopic ◽  
Acceleration Voltage ◽  
Scanning Electron

The authors have investigated the dissolution process of human cholesterol gallstones using a scanning electron microscope(SEM). This study was carried out by comparing control gallstones incubated in beagle bile with gallstones obtained from patients who were treated with chenodeoxycholic acid(CDCA).The cholesterol gallstones for this study were obtained from 14 patients. Three control patients were treated without CDCA and eleven patients were treated with CDCA 300-600 mg/day for periods ranging from four to twenty five months. It was confirmed through chemical analysis that these gallstones contained more than 80% cholesterol in both the outer surface and the core.The specimen were obtained from the outer surface and the core of the gallstones. Each specimen was attached to alminum sheet and coated with carbon to 100Å thickness. The SEM observation was made by Hitachi S-550 with 20 kV acceleration voltage and with 60-20, 000X magnification.

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