This paper reports the visual observations of the formation and growth of clathrate hydrate crystals on the surface of a water droplet exposed to gaseous methane, ethane, or propane. The hydrate crystals formed and grew at the guest-water interface. The nucleation of the hydrate first occurred at a random point on the water droplet and then grew to form a polycrystalline layer covering the surface. We observed the individual crystals that constitute the polycrystalline hydrate layer and classified the morphology of the hydrate crystals depending on the system subcooling ∆T sub , the difference between the system temperature and the guest-hydrate-water three-phase equilibrium temperature corresponding to the system pressure. As a general trend, at ∆T sub g 3.0 K, the shape of hydrate crystals is typically swordlike or triangular, and the shape changes to a polygon at ∆T sub from 2.0 to 3.0 K, and then to larger-sized polygons with one side of the polygon typically 0.5-1.0 mm in length. It may be concluded that the crystal morphology of the hydrate crystals formed at the interface between the liquid water and methane, ethane or propane gas can be classified using ∆T sub as the common criterion. The lateral growth rate of the hydrate crystal were also measured and presented.

This paper reports the visual observations of the formation and growth of clathrate hydrate crystals on the surface of a water droplet exposed to a methane þ ethane þ propane gas mixture. The compositions of the methane þ ethane þ propane gas mixtures are (i) 99.47:0.51:0.02, (ii) 94.1:5.8:0.1, and (iii) 90:7:3 molar ratio. The nucleation of the hydrate first occurred at a random point on the water droplet and then the hydrate grew to form a polycrystalline layer covering the droplet. We visually observed the individual crystals that constitute the polycrystalline hydrate layer and classified the morphology of the hydrate crystals depending on the system subcooling ΔT sub and system pressure. It was found that the size of the individual mixed-gas hydrate crystals decreased with the increasing ΔT sub as observed for the simple hydrates each formed with methane, ethane, or propane. The size of the individual crystals decreased with the increasing molar ratio of methane in the gas mixtures. The mixed-gas hydrate crystals exhibited a morphology different from that of the simple methane hydrate. We also measured the lateral growth rates of the hydrate-film propagation. In any of the systems, the rates increased with increasing ΔT sub as observed in other hydrate-forming systems.

The aim of this study was to use small unmanned aerial vehicles (UAVs) for determining high-resolution normalized difference vegetation index (NDVI) values. Subsequently, these results were used to assess their correlations with fertilizer application levels and the yields of rice and wheat crops. For multispectral sensing, we flew two types of small UAVs (DJI Phantom 4 and DJI Phantom 4 Pro)—each equipped with a compact multispectral sensor (Parrot Sequoia). The information collected was composed of numerous RGB orthomosaic images as well as reflectance maps with spatial resolution greater than a ground sampling distance of 10.5 cm. From 223 UAV flight campaigns over 120 fields with a total area coverage of 77.48 ha, we determined that the highest efficiency for the UAV-based remote sensing measurement was approximately 19.8 ha per 10 min while flying 100 m above ground level. During image processing, we developed and used a batch image alignment algorithm—a program written in Python language–to calculate the NDVI values in experimental plots or fields in a batch of NDVI index maps. The color NDVI distribution maps of wide rice fields identified differences in stages of ripening and lodging-injury areas, which accorded with practical crop growth status from aboveground observation. For direct-seeded rice, variation in the grain yield was most closely related to that in the NDVI at the early reproductive and late ripening stages. For wheat, the NDVI values were highly correlated with the yield ( R 2 = 0.601–0.809) from the middle reproductive to the early ripening stages. Furthermore, using the NDVI values, it was possible to differentiate the levels of fertilizer application for both rice and wheat. These results indicate that the small UAV-derived NDVI values are effective for predicting yield and detecting fertilizer application levels during rice and wheat production.

Certain xylanases from family GH10 are highly expressed during secondary wall deposition, but their function is unknown. We carried out functional analyses of the secondary-wall specific PtxtXyn10A in hybrid aspen (Populus tremula × tremuloides). PtxtXyn10A function was analysed by expression studies, overexpression in Arabidopsis protoplasts and by downregulation in aspen. PtxtXyn10A overexpression in Arabidopsis protoplasts resulted in increased xylan endotransglycosylation rather than hydrolysis. In aspen, the enzyme was found to be proteolytically processed to a 68 kDa peptide and residing in cell walls. Its downregulation resulted in a corresponding decrease in xylan endotransglycosylase activity and no change in xylanase activity. This did not alter xylan molecular weight or its branching pattern but affected the cellulose-microfibril angle in wood fibres, increased primary growth (stem elongation, leaf formation and enlargement) and reduced the tendency to form tension wood. Transcriptomes of transgenic plants showed downregulation of tension wood related genes and changes in stress-responsive genes. The data indicate that PtxtXyn10A acts as a xylan endotransglycosylase and its main function is to release tensional stresses arising during secondary wall deposition. Furthermore, they suggest that regulation of stresses in secondary walls plays a vital role in plant development.