The presence of structure H (sH) methane hydrate in natural environments, in addition to the well-known structure-I (sI) and II (sII) hydrates, has recently been documented. Methane in the presence of condensates (C5-C7) forms sH hydrate at lower pressure than the sI hydrate. Thus, the occurrence of sH methane hydrate is likely to have both beneficial and negative practical implications. On the...

The lattice constants of hydrogenated and deuterated CH4-, CO2-, Xe- (clathrate structure type I) and N2-hydrates (clathrate structure type II) from 10 K up to the stability limit were established in neutron- and synchrotron diffraction experiments and were used to derive the related thermal expansivities. The following results emerge from this analysis: (1) The differences of expansivities of ...

Magnesium chloride hydrates are characterized as promising energy storage materials in the built-environment. During the dehydration of these materials, there are chances for the release of harmful HCl gas, which can potentially damage the material as well as the equipment. Hydrolysis reactions in magnesium chloride hydrates are subject of study for industrial applications. However, the informa...

calcium aluminates (ca) are the most important hydraulically setting cements used for preparing refractory castables, because they develop high strength at very early ages after placements.  the anhydrous phases of this kind of cements are ca, ca2 and traces of c12a7 and alpha-alumina. the major hydraulic phase in all of the ca cements including ciment fondue is ca. once hydrated, it starts to ...

The kinetics of nucleation of one-component gas hydrates in aqueous solutions are analyzed. The size of the hydrate nucleus and the work for nucleus formation are determined as functions of the supersaturation Dm: Expressions for the stationary rate J of hydrate nucleation are derived. These expressions describe the JðDmÞ dependence for homogeneous nucleation and for heterogeneous nucleation at...

In the course of a study on spectral behaviour of alloxazine and its methylated derivatives light absorption spectra and apparent pKa values of individual ionic species have been evaluated *. Alloxazine, lumichrome and 3-methyllumichrome in aqueous alkaline solutions undergo a slow base-catalysed reaction which manifests by evident changes in the light absorption spectra (Fig. 1), while 1-methy...

The JAPEX/JNOC/GSC et al. Mallik 5L-38 gas hydrate research well was drilled to 1166 m through about 200 m of subpermafrost gas-hydrate-bearing sediments under the Mackenzie Delta, Canada. An extensive logging program was completed to characterize in situ the physical properties of the sediments where gas hydrate fills as much as 80% of the pore space. Analysis of sonic logging waveform show th...