Measurement of Ice-Binding Protein Inhibition of Non-ice Crystal Growth.

The kinetic hydrate inhibitor (KHI) was developed to prevent the formation of undesirable gas hydrate crystals in natural gas pipelines. Studies of antifreeze proteins (AFPs) are gaining attention in the natural gas research field due to their performance in crystal growth inhibition, excellent biodegradation, and low toxicity. Studies of AFPs may provide clues for developing future commercial KHIs used offshore.

Diamond formation from methane hydrate under the internal conditions of giant icy planets.

Hydrocarbon chemistry in the C-O-H system at high pressure and high temperature is important for modelling the internal structure and evolution of giant icy planets, such as Uranus and Neptune, as their interiors are thought to be mainly composed of water and methane. In particular, the formation of diamond from the simplest hydrocarbon, i.e.

Structural evolution of methane hydrate under pressures up to 134 GPa.

High-pressure experiments were performed to understand the structural evolution of methane hydrate (MH) up to 134 GPa using x-ray powder diffraction (XRD) and Raman spectroscopy with diamond anvil cells. XRD revealed the distinct changes in the diffraction lines of MH owing to phase transition from a guest-ordered state phase [MH-III(GOS)] to a new high-pressure phase (MH-IV) at 33.8-57.

Effect of Ammonia on Methane Hydrate Stability under High-Pressure and High-Temperature Conditions.

High-pressure experiments were conducted to investigate the stability and phase transition of methane hydrate (MH) in the water-methane-ammonia system at room-to-high temperatures employing Raman spectroscopy and synchrotron X-ray powder diffraction, in combination with an externally heated diamond anvil cell. The results revealed that, at room temperature, MH undergoes phase transitions from MH-I to MH-II at ∼1.0 GPa and from MH-II to MH-III at ∼2.

Correction: X-ray CT observation and characterization of water transformation in heavy objects.

Correction for 'X-ray CT observation and characterization of water transformation in heavy objects' by Satoshi Takeya et al., Phys. Chem.

X-ray CT observation and characterization of water transformation in heavy objects.

Nondestructive observations and characterization of low-density materials composed of low-Z elements, such as water or its related substances, are essential for materials and life sciences. However, visualizing these compounds and their phase changes is still challenging. In this study, an approach to X-ray imaging of water-related substances in heavy objects without the use of contrast agents is proposed.

Kinetic inhibition effect of Type I and III antifreeze proteins on unidirectional tetrahydrofuran hydrate crystal growth.

Experiments were performed to evaluate the kinetic inhibition effect of Type I and Type III antifreeze proteins (AFPs), polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP) on the growth of tetrahydrofuran (THF) clathrate hydrate crystals using the unidirectional growth technique. The crystal growth interface shifted under an applied temperature gradient over a given time. Type I AFP was the most effective kinetic inhibitor, followed by PVP, Type III AFP and PVA.

In situ chamber built for clarifying the relationship between methane hydrate crystal morphology and gas permeability in a thin glass micromodel cell.

We developed a novel in situ chamber to investigate the relationship between gas hydrate crystal morphology and gas permeability in a glass micromodel that mimics marine sediment. This high-pressure experimental chamber was able to use a thin glass cell without high pressure resistance. The formation of methane hydrate (MH) in the glass micromodel was observed in situ.

Protocol for Measuring the Thermal Properties of a Supercooled Synthetic Sand-water-gas-methane Hydrate Sample.

Methane hydrates (MHs) are present in large amounts in the ocean floor and permafrost regions. Methane and hydrogen hydrates are being studied as future energy resources and energy storage media. To develop a method for gas production from natural MH-bearing sediments and hydrate-based technologies, it is imperative to understand the thermal properties of gas hydrates.