This paper reports the visual observation of the formation and growth of clathrate hydrate crystals in liquid water presaturated with a simulated natural gas (methane þ ethane þ propane mixture). The compositions of the methane þ ethane þ propane gas mixtures are (i) 90:7:3, (ii) 94.1:5.8:0.1, and (iii) 99.47:0.51:0.02 in molar ratio. A hydrate film first formed to intervene between the mixed gas and liquid water, and then hydrate crystals grew in the liquid water phase. The morphology of hydrate crystals grown in liquid water distinctly varied depending on the system subcooling ΔT sub . When ΔT sub is smaller than ∼7 K, hydrate crystal growth in liquid water was not observed. At ∼7 K < ΔT sub < ∼12 K, hydrate crystals with polygonal morphology were observed. At ΔT sub > ∼12 K, polygonal crystals were replaced by dendritic crystals. These changes in morphology were observed with all three gas mixtures. It was found that the morphology in the system with mixed gas of the molar ratio 99.47:0.51:0.02 was different from those of the other two systems. We also observed the hydrate crystals floating to the hydrate film from liquid water phase. Floating crystals formed in the bulk of liquid water, attached the hydrate film, and then continued to grow in liquid water. The morphology of floating crystals varied with ΔT sub and the gas composition.

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This study was conducted with the objective of improving the stability of perovskite solar cells by using the unique characteristics of graphene in order to facilitate the widespread application of such solar cells, for example, in multijunction devices. We consequently developed a new transfer method for graphene using vacuum lamination and, using graphene, successfully fabricated a perovskite solar cell that does not require a hole-transport layer. Initial stability tests indicated that the new device has better stability than a control perovskite solar cell using spiro-OMeTAD. Although the new solar cell design exhibited poorer cell performance than the control, we determined via modeling that its performance can be improved by modifying the interface state between perovskite and graphene or by modulating the work function of graphene.

Magnonic crystals are interesting for spin-wave based data processing. We investigate one-dimensional magnonic crystals (1D MCs) consisting of bistable Co20Fe60B20 nanostripes separated by 75 nm wide air gaps. By adjusting the magnetic history, we program a single stripe of opposed magnetization in an otherwise saturated 1D MC. Its influence on propagating spin waves is studied via broadband microwave spectroscopy. Depending on an in-plane bias magnetic field, we observe spin wave phase shifts of up to almost π and field-controlled attenuation attributed to the reversed nanostripe. Our findings are of importance for magnetologics, where the control of spin wave phases is essential.

This paper reports the growth and characterization of c-axis-oriented NbS 2 thin films on SiO 2 /Si substrate by ambient pressure chemical vapor deposition (CVD) using a generic metal chloride source.We found that NbS 2 nanosheets can be grown directly on the SiO 2 /Si substrate with the aid of hydrogen gas mixed in the carrier gas. Detailed examination of the growth parameters was made possible using a separateflow CVD apparatus. It appears that the major cause of the misorientation is the off-stoichiometry with surplus Nb. The quality of the films was evaluated by X-ray diffraction and Raman spectroscopy as well as resistivity measurements at low temperatures. They showed a resistivity minimum at the same temperature of the charge density wave (CDW) transition for a bulk single crystal of 3R-NbS 2 .