Window effect in a discretized model for diffusion of a chain in one dimension

2005 ◽  
Vol 71 (2) ◽  
Author(s):  
G. Terranova ◽  
C. M. Aldao ◽  
H. O. Mártin
2003 ◽  
Vol 67 (3) ◽  
Author(s):  
S. E. Guidoni ◽  
H. O. Mártin ◽  
C. M. Aldao

Author(s):  
H. E. Daniels ◽  
F. Smithies

1. Introduction and summary. A chain of N links is allowed to assume a random configuration in space. The extent of the chain in any direction is defined as the shortest distance between a pair of planes perpendicular to that direction, such that the chain is contained entirely between them. In the present paper the probability distribution of the extent is discussed, starting with a chain in one dimension for which formulae are derived for the probability and mean extent for all values of N. The limiting forms for large N are then considered. The results are extended to the case of a chain in three dimensions, and it is shown that the extents in two directions at right angles tend to be independently distributed when N is large. It is assumed that the links are infinitely thin, so that a point in space may be occupied by the chain any number of times.


1974 ◽  
Vol 29 (1-2) ◽  
pp. 10-12 ◽  
Author(s):  
Horst Sabrowsky ◽  
Welf Bronger ◽  
Dieter Schmitz

The ternary oxide K2PdO2 has been prepared by a reaction between K2O and PdO. X-ray investigations suggest a chain-structure-type which corresponds to that of K2PtS2. The planar oxygen coordinations of the palladium atoms are connected laterally in one dimension. The orthorhombic unit cell (a = 8.523, b = 6.089, c = 3.119 Å) contains two formula units.


2006 ◽  
Vol 74 (2) ◽  
Author(s):  
G. Terranova ◽  
H. O. Mártin ◽  
C. M. Aldao
Keyword(s):  

2018 ◽  
Vol 74 (5) ◽  
pp. 523-528
Author(s):  
Abdel-Fattah Shihada ◽  
Frank Weller ◽  
Werner Massa

Organolead compounds are of interest mainly as catalysts and organolead halides have proved to be very efficient materials for solar cells. Two organolead(IV) dimethylarsinates, namely catena-poly[[triphenyllead(IV)]-μ-chlorido-[triphenyllead(IV)]-μ-dimethylarsinato-κ2 O:O′], [Pb2(C6H5)6(C2H6AsO2)Cl] n or [(Ph3Pb)2Cl(O2AsMe2)], (1), and poly[chlorido(μ3-dimethylarsinato-κ3 O:O,O′:O′)diphenyllead(IV)], [Pb(C6H5)2(C2H6AsO2)Cl] n or [(Ph2ClPb)(O2AsMe2)], (2), together with the triphenyllead(IV) diphenylphosphinate catena-poly[[triphenyllead(IV)]-μ-diphenylphosphinato-κ2 O:O′], [Pb(C6H5)3(C12H10O2P)] n or [(Ph3Pb)(O2PPh2)], (3), have been synthesized and characterized by single-crystal X-ray diffraction, IR spectroscopy and mass spectrometry. In (1), a chain structure was found with alternating chloride and Pb—O—As—O—Pb arsinate bridges between five-coordinate PbIV atoms. In (2), bidentate and chelate-like bonded dimethylarsinate ligands form double chains with heptacoordinated PbIV atoms. In (3), a pentacoordinated PbIV atom is connected by Pb—O—P—O—Pb phosphinate bridges to form a linear chain. Obviously, the steric demand of the phenyl ligands at PbIV reduces the possibility of interconnections via polydentate ligands to one dimension only. Thus, no metal–organic frameworks (MOF) are formed but instead various chain structures are observed.


Author(s):  
H. Todokoro ◽  
S. Nomura ◽  
T. Komoda

It is interesting to observe polymers at atomic size resolution. Some works have been reported for thorium pyromellitate by using a STEM (1), or a CTEM (2,3). The results showed that this polymer forms a chain in which thorium atoms are arranged. However, the distance between adjacent thorium atoms varies over a wide range (0.4-1.3nm) according to the different authors.The present authors have also observed thorium pyromellitate specimens by means of a field emission STEM, described in reference 4. The specimen was prepared by placing a drop of thorium pyromellitate in 10-3 CH3OH solution onto an amorphous carbon film about 2nm thick. The dark field image is shown in Fig. 1A. Thorium atoms are clearly observed as regular atom rows having a spacing of 0.85nm. This lattice gradually deteriorated by successive observations. The image changed to granular structures, as shown in Fig. 1B, which was taken after four scanning frames.


Author(s):  
Elrnar Zeitler

Considering any finite three-dimensional object, a “projection” is here defined as a two-dimensional representation of the object's mass per unit area on a plane normal to a given projection axis, here taken as they-axis. Since the object can be seen as being built from parallel, thin slices, the relation between object structure and its projection can be reduced by one dimension. It is assumed that an electron microscope equipped with a tilting stage records the projectionWhere the object has a spatial density distribution p(r,ϕ) within a limiting radius taken to be unity, and the stage is tilted by an angle 9 with respect to the x-axis of the recording plane.


Author(s):  
B. D. Athey ◽  
A. L. Stout ◽  
M. F. Smith ◽  
J. P. Langmore

Although there is general agreement that Inactive chromosome fibers consist of helically packed nucleosomes, the pattern of packing is still undetermined. Only one of the proposed models, the crossed-linker model, predicts a variable diameter dependent on the length of DNA between nucleosomes. Measurements of the fiber diameter of negatively-stained and frozen- hydrated- chromatin from Thyone sperm (87bp linker) and Necturus erythrocytes (48bp linker) have been previously reported from this laboratory. We now introduce a more reliable method of measuring the diameters of electron images of fibrous objects. The procedure uses a modified version of the computer program TOTAL, which takes a two-dimensional projection of the fiber density (represented by the micrograph itself) and projects it down the fiber axis onto one dimension. We illustrate this method using high contrast, in-focus STEM images of TMV and chromatin from Thyone and Necturus. The measured diameters are in quantitative agreement with the expected values for the crossed-linker model for chromatin structure


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