The tendency of oxygen atoms to form just two bonds with a bond angle smaller than 180 allows the appearance of low energy atomic motions related to internal rotational degrees of freedom which, in a first approximation, involve neither bending nor stretching of bonds (“rigid unit modes” in silicates, “floppy modes” in glasses). A huge variety of compounds exhibit the oxygenbridge X-O-X basic u...

We investigate the thermal expansion of crystalline SiO2 in the β– cristobalite and the β-quartz structure with path integral Monte Carlo (PIMC) techniques. This simulation method allows to treat low-temperature quantum effects properly. At temperatures below the Debye temperature, thermal properties obtained with PIMC agree better with experimental results than those obtained with classical Mo...

The phases containing multiple chains in the series Ba",+1[Si2mOsm+d those with triple (m = 3), quadruple (m = 4) and quintuple (m = 5) tetrahedral chains were investigated by high resolution transmission electron microscopy. The resulting images could be correlated with the structures. Variations of the chain multiplicity (m) within single crystals were observed as well as faults in the packin...

Introduction: Impact-generated hydrothermal systems may have caused widespread alteration of the crust on early Mars. We previously explored the range of alteration products using several Martian meteorites as crustal proxies: LEW88516 [1-3], Dhofar 378, Chassigny [4], and Nakhla [5]. Overall, the dominating alteration phases are oxides, hydroxides, clay minerals, and other hydrous silicates. O...

In this paper we consider a new interconnection network motivated by molecular structure of a chemical compound SiO4. The different forms of silicates available in nature lead to the introduction of the silicate networks. We investigate various parameters related to this network. We provide an addressing scheme for the nodes of the network and also an algorithm that enables us to draw the silic...

A method for analysis of high-resolution quasielastic neutron scattering (QENS) spectra of water in porous media is proposed and applied to the case of water in hydrated tricalcium and dicalcium silicates. We plot the normalized frequency-dependent susceptibility as a function of a scaling variable [omega]/omega(p), where omega(p) is the peak position of the susceptibility function. QENS data h...

Mesostructured silicates containing metal nanoparticles have been synthesised via templating around a pre-formed, metal-containing mesophase using a non-ionic surfactant.

In the present study, interactive effects of D1 and D2 dopamine receptors antagonists and different periods of lithium pretreatment on morphine dependence in mice have been investigated. This study was designed to investigate whether the hypothesis that lithium and dopaminergic mechanisms via their effects on phosphoinositide pathways and calcium flux could influence morphine withdrawal respons...

Objective(s):Theneuroprotective effect of lithium has been attributed to its therapeutic action. However, the role of glial cells particularly astrocytes, and the possible interactions between neurons and astrocytes in neuroprotective effects of lithium have been disregarded. Thus, the aim of this study was to evaluate the direct effects of lithium on brain derived neurotrophic factor (BDNF) an...