Structural Groupings in Borate Glasses

1985 ◽  
Vol 61 ◽  
Author(s):  
Philip J. Bray
Keyword(s):  
Long Range ◽  
Random Network ◽  
Three Dimensional ◽  
Silicate Glasses ◽  
Borate Glasses ◽  
Oxide Glasses ◽  
Atomic Arrangement ◽  
Random Manner ◽  
Continuous Random Network

A. A. Lebedev developed a crystallite model for glasses in the 1920's which was supported by the 1930 publication of Randall, Rooksby, and Cooper But, the 1932 publication by Zachariasen entitled “The Atomic Arrangement in Glass” introduced the Warren and Zachariasen continuous random network (CRN) model. In that model, as applied to oxide glasses, oxygen polyhedra surrounding cations (e.g. SiO4 tetrahedra in silicate glasses) are linked together in a random manner to form extensive three-dimensional networks which do not exhibit long-range symmetry or periodicity. Zachariasen did assume that the forces between atoms in glasses and crystals are essentially the same, and noted the same polyhedra in both, but did not discuss any further possible correspondence between glasses and crystals.

scholarly journals Structure Dependence of Poisson’s Ratio in Cesium Silicate and Borate Glasses

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2837
Author(s):  
Martin B. Østergaard ◽  
Mikkel S. Bødker ◽  
Morten M. Smedskjaer
Keyword(s):  
Poisson’S Ratio ◽  
Network Connectivity ◽  
Silicate Glasses ◽  
Poisson's Ratio ◽  
Borate Glasses ◽  
Oxide Glasses ◽  
Topological Constraint ◽  
Binary Glass ◽  
The Difference ◽  
Positive Correlations

In glass materials, Poisson’s ratio (ν) has been proposed to be correlated with a variety of features, including atomic packing density (Cg), liquid fragility (m), and network connectivity. To further investigate these correlations in oxide glasses, here, we study cesium borate and cesium silicate glasses with varying modifier/former ratio given the difference in network former coordination and because cesium results in relatively high ν compared to the smaller alkali modifiers. Within the binary glass series, we find positive correlations between ν on one hand and m and Cg on the other hand. The network former is found to greatly influence the correlation between ν and the number of bridging oxygens (nBO), with a negative correlation for silicate glasses and positive correlation for borate glasses. An analysis based on topological constraint theory shows that this difference cannot be explained by the effect of superstructural units on the network connectivity in lithium borate glasses. Considering a wider range of oxide glasses from the literature, we find that ν generally decreases with increasing network connectivity, but with notable exceptions for heavy alkali borate glasses and calcium alumino tectosilicate glasses.

Analysis of the Si-ON-Insulator Structure by Modeling of the Interface Atomic Arrangement

1983 ◽  
Vol 25 ◽  
Author(s):  
T. Saito ◽  
Y. Yamakoshi ◽  
I. Ohdomari
Keyword(s):  
Network Model ◽  
Random Network ◽  
Interface Energy ◽  
Atomic Arrangement ◽  
Bond Stretching ◽  
Distortion Energy ◽  
Bond Distortion ◽  
Bond Bending ◽  
Continuous Random Network ◽  
Type Potential

ABSTRACTA structure of interface between crystalline Si (c-Si) and underlying SiO2 film formed by Si-on-Insulator technique has been analyzed by modeling of interface atomic arrangement. A ball-and-spoke model of a stoichiometrically abrupt c-Si/SiO2 interface has been constructed by connecting a (100) c-Si lattice and a continuous random network model of amorphous SiO2 . A Keating-type potential has been used for the interatomic interactions. The bond bending distortion energy of both Si and O atoms increases at the interface, while the bond stretching energy is negligibly small. The amount of interface energy due to bond distortion is 0.20J/m2.

scholarly journals HiChIP and Hi-C Protocol Optimized for Primary Murine T Cells

2021 ◽  
Vol 4 (3) ◽  
pp. 49
Author(s):  
Tomas Zelenka ◽  
Charalampos Spilianakis
Keyword(s):  
T Cells ◽  
Long Range ◽  
Three Dimensional ◽  
Cell Types ◽  
Range Interaction ◽  
Chromatin Interactions ◽  
Optimized Protocol ◽  
Long Range Interaction ◽  
Chromatin Compactness ◽  
Detailed Protocol

The functional implications of the three-dimensional genome organization are becoming increasingly recognized. The Hi-C and HiChIP research approaches belong among the most popular choices for probing long-range chromatin interactions. A few methodical protocols have been published so far, yet their reproducibility and efficiency may vary. Most importantly, the high frequency of the dangling ends may dramatically affect the number of usable reads mapped to valid interaction pairs. Additionally, more obstacles arise from the chromatin compactness of certain investigated cell types, such as primary T cells, which due to their small and compact nuclei, impede limitations for their use in various genomic approaches. Here we systematically optimized all the major steps of the HiChIP protocol in T cells. As a result, we reduced the number of dangling ends to nearly zero and increased the proportion of long-range interaction pairs. Moreover, using three different mouse genotypes and multiple biological replicates, we demonstrated the high reproducibility of the optimized protocol. Although our primary goal was to optimize HiChIP, we also successfully applied the optimized steps to Hi-C, given their significant protocol overlap. Overall, we describe the rationale behind every optimization step, followed by a detailed protocol for both HiChIP and Hi-C experiments.

scholarly journals Advances in Liquid Crystalline Epoxy Resins for High Thermal Conductivity

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1302
Author(s):  
Younggi Hong ◽  
Munju Goh
Keyword(s):  
Thermal Conductivity ◽  
Network Structure ◽  
Epoxy Resins ◽  
Liquid Crystalline ◽  
Random Network ◽  
Three Dimensional ◽  
Heat Insulator ◽  
Liquid Crystalline Epoxy ◽  
Thermally Conductive ◽  
Substantial Interest

Epoxy resin (EP) is one of the most famous thermoset materials. In general, because EP has a three-dimensional random network, it possesses thermal properties similar to those of a typical heat insulator. Recently, there has been substantial interest in controlling the network structure of EP to create new functionalities. Indeed, the modified EP, represented as liquid crystalline epoxy (LCE), is considered promising for producing novel functionalities, which cannot be obtained from conventional EPs, by replacing the random network structure with an oriented one. In this paper, we review the current progress in the field of LCEs and their application to highly thermally conductive composite materials.

The Structure of Ion-Implanted Amorphous Silicon

1998 ◽  
Vol 540 ◽  
Author(s):  
J. M. Gibson ◽  
J-Y. Cheng ◽  
P. Voyles ◽  
M.M.J. TREACY ◽  
D.C. Jacobson
Keyword(s):  
Amorphous Silicon ◽  
Network Model ◽  
Random Network ◽  
Amorphous Semiconductors ◽  
Range Order ◽  
Medium Range Order ◽  
Medium Range ◽  
Large Heat ◽  
Continuous Random Network ◽  
Ion Implanted

AbstractUsing fluctuation microscopy, we show that ion-implanted amorphous silicon has more medium-range order than is expected from the continuous random network model. From our previous work on evaporated and sputtered amorphous silicon, we conclude that the structure is paracrystalline, i.e. it possesses crystalline-like order which decays with distance from any point. The observation might pose an explanation for the large heat of relaxation that is evolved by ion-implanted amorphous semiconductors.

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