In situ observation of mono-molecular growth steps on aqueous solution grown crystals and the transport of molecules to the crystals

Direct in situ observation of mono-molecular growth steps on a crystal growing in an aqueous solution became possible. The combination of this method with high resolution Schlieren methods or interferometry, permits the growth mechanism of crystals to be investigated directly. Since the observation of growth steps on crystals is the most direct and sensitive way for investigating a crystal growth mechanism, it would contribute to revealing fundamental differences between the growth in space and on Earth. The method was recently extended to in situ observation of the growth processes at high temperatures (1800K)

Application of Hoffman modulation contrast microscopy coupled with three-wavelength two-beam interferometry to the in situ direct observation of the growth process of a crystal in microgravity

Direct visualization of three dimensional transfer process of both heat and mass around a growing crystal and mono-molecular growth layers on the surface is possible in situ by means of high resolution Hoffman modulation contrast microscopy coupled with three wavelength two beam Mach-Zehnder interferometry. This in situ observation is very suitable for the verification of the growth mechanism of a crystal in a solution or a melt in microgravity

Very Low Nucleation Rates of Glucose Isomerase Crystals under Microgravity in the International Space Station

In situ observation of the nucleation and growth of glucose isomerase (GI) crystals under microgravity was conducted using an optical microscope during the first flight of the Advanced Nano Step project undertaken in the International Space Station (ISS). Very low apparent nucleation rates (J’) of GI crystals in the solution and on the substrate of the growth container were confirmed compared with those on the ground. In particular, J’ of GI crystals in the solution were a few times lower than that on the substrate. The growth rates (R) of the {101} faces of GI crystals on the substrate and the apparent growth rates (R’) in the solution were measured. The very low nucleation rates allowed us to successfully measure R at a very high supersaturation region (up to ln(C/Ce) = 6), at which R cannot be measured on the ground

Dissolution Processes at Step Edges of Calcite in Water Investigated by High-Speed Frequency Modulation Atomic Force Microscopy and Simulation

The microscopic understanding of the crystal growth and dissolution processes have been greatly advanced by the direct imaging of nanoscale step flows by atomic force microscopy (AFM), optical interferometry, and X-ray microscopy. However, one of the most fundamental events that govern their kinetics, namely, atomistic events at the step edges, have not been well understood. In this study, we have developed high-speed frequency modulation AFM (FM-AFM) and enabled true atomic-resolution imaging in liquid at ∼1 s/frame, which is ∼50 times faster than the conventional FM-AFM. With the developed AFM, we have directly imaged subnanometer-scale surface structures around the moving step edges of calcite during its dissolution in water. The obtained images reveal that the transition region with typical width of a few nanometers is formed along the step edges. Building upon insight in previous studies, our simulations suggest that the transition region is most likely to be a Ca(OH)2 monolayer formed as an intermediate state in the dissolution process. On the basis of this finding, we improve our understanding of the atomistic dissolution model of calcite in water. These results open up a wide range of future applications of the high-speed FM-AFM to the studies on various dynamic processes at solid-liquid interfaces with true atomic resolution. © 2017 American Chemical Society.Embargo Period 12 month

Evidence for Solution-Mediated Phase Transitions in Kidney Stones: Phase Transition Exacerbates Kidney Stone Disease

Maruyama M., Tanaka Y., Momma K., et al. Evidence for Solution-Mediated Phase Transitions in Kidney Stones: Phase Transition Exacerbates Kidney Stone Disease. Crystal Growth and Design 23, 4285 (2023); https://doi.org/10.1021/acs.cgd.3c00108.In this study, we investigated calcium oxalate (CaOx) kidney stones and showed direct evidence of the solution-mediated phase transition of calcium oxalate dihydrate (COD; the metastable phase) to calcium oxalate monohydrate (COM; the stable phase). We examined the crystal phases, crystal textures, and protein distributions within thin sections of calcium oxalate kidney stones. Observation with a polarized-light microscope showed that the outline of the mosaic texture, in which COM crystals are assembled in a mosaic pattern, roughly coincides with COD’s crystallographically stable face angles. Microfocus X-ray CT measurement captured the intermediate process of the phase transition, starting inside the COD single crystal and gradually transforming to COM crystals. In addition, the distribution of osteopontin and prothrombin fragment-1, common proteins contained in urine and visualized by multicolor fluorescence immunostaining, showed no apparent striations inside the COM single crystals with the mosaic texture, although the striation is apparent inside the COD single crystals. This is probably because the phase transition of mosaic-like COM occurred in a semiclosed system inside the COD single crystal, so the effect of periodic (day-night, seasonal, etc.) urinary protein concentration changes was small. On the other hand, striations were visible in concentrically laminated COM. This indicated that concentrically laminated COM formed in response to the changes in urinary protein concentrations. From the above, we conclude that the COD single crystals and the concentrically laminated COM seen in CaOx stones are primary structures, and the mosaic COM is a secondary structure that is a pseudomorph formed by the solution-mediated phase transition from COD single crystals