Numerical simulations are a valuable tool for the design and optimization of crystal growth processes because experimental investigations are expensive and access to internal parameters is limited. These technical limitations are particularly large for ammonothermal growth of bulk GaN, an important semiconductor material. This review presents an overview of the literature on simulations targeting ammonothermal growth of GaN. Approaches for validation are also reviewed, and an overview of available methods and data is given. Fluid flow is likely in the transitional range between laminar and turbulent; however, the time-averaged flow patterns likely tend to be stable. Thermal boundary conditions both in experimental and numerical research deserve more detailed evaluation, especially when designing numerical or physical models of the ammonothermal growth system. A key source of uncertainty for calculations is fluid properties under the specific conditions. This originates from their importance not only in numerical simulations but also in designing similar physical model systems and in guiding the selection of the flow model. Due to the various sources of uncertainty, a closer integration of numerical modeling, physical modeling, and the use of measurements under ammonothermal process conditions appear to be necessary for developing numerical models of defined accuracy.

Purpose: To evaluate the incidence of the Descemet membrane (DM) folds after deep anterior lamellar keratoplasty (DALK) in treating keratoconus. We also evaluated the influence of DM folds and corneal higher-order aberrations (HOAs) on visual acuity after DALK. Methods: This retrospective study included 89 consecutive eyes of 87 patients who underwent DALK for the treatment of keratoconus at Tokyo Dental College Ichikawa General Hospital from April 2002 to June 2017. The presence or absence of DM folds was determined by slitlamp microscopy. Visual acuity after DALK was compared between the eyes with and without DM folds. Corneal HOAs of the anterior and posterior surfaces and the total cornea were measured by anterior segment optical coherence tomography. Correlations among the presence of DM folds, corneal HOAs, and visual acuity were analyzed. Results: The Descemet membrane folds developed in 28.1% (25/89) eyes after DALK for the treatment of keratoconus. However, there were no significant differences in postoperative visual acuity between the eyes with and without DM folds at 1, 3, 6, and 12 months (P=0.739, P=0.106, P=0.223, and P=0.186, respectively). The visual acuity at 12 months was significantly correlated with corneal HOAs within a 4-mm diameter (anterior surface: R=0.546, P=0.003; total cornea: R=0.506, P=0.007). Conclusions: Larger corneal HOAs, but not the presence of DM folds, were associated with poor visual acuity after DALK. In treating advanced keratoconus with DALK, it is important to minimize postoperative corneal HOAs, although DALK improves visual acuity by reducing HOAs due to keratoconus.

A novel acidic ionic liquid, 1-methylimidazolium chlorosulfate ([HMIm]SO3Cl), with dual Brønsted–Lewis acidity was synthesized. This compound provided better catalytic performance in esterification and dehydration of fructose to 5-hydroxymethylfurfural (HMF) than acidic ionic liquids with only Brønsted or Lewis acidity.

Thermal boundary conditions for numerical simulations of ammonothermal GaN crystal growth are investigated. A global heat transfer model that includes the furnace and its surroundings is presented, in which fluid flow and thermal field are treated as conjugate in order to fully account for convective heat transfer. The effects of laminar and turbulent flow are analyzed, as well as those of typically simultaneously present solids inside the autoclave (nutrient, baffle, and multiple seeds). This model uses heater powers as a boundary condition. Machine learning is applied to efficiently determine the power boundary conditions needed to obtain set temperatures at specified locations. Typical thermal losses are analyzed regarding their effects on the temperature distribution inside the autoclave and within the autoclave walls. This is of relevance because autoclave wall temperatures are a convenient choice for setting boundary conditions for simulations of reduced domain size. Based on the determined outer wall temperature distribution, a simplified model containing only the autoclave is also presented. The results are compared to those observed using heater-long fixed temperatures as boundary condition. Significant deviations are found especially in the upper zone of the autoclave due to the important role of heat losses through the autoclave head.

Ionic liquids (ILs) have attracted great attention as green solvents, heat carriers, and electrolytes. They can be obtained with specific thermophysical properties and functions by changing the kind of species of cations and anions. Knowledge of the fundamental thermophysical properties of ILs, such as their densities, viscosities, and thermal conductivities, is needed to design ILs with desirable thermophysical properties. In this chapter, we will review the various measurement results for the thermal conductivities of the pure components of ILs and methods for predicting the thermal conductivity of an IL, which are based on its structure and physical properties, by conducting correlations between these parameters. In the recent years, the thermal conductivities of IoNano fluids, which comprise of nanoparticles dispersed in an IL, have attracted great attention. Therefore, we will review the unique thermal conductivities of IoNano fluids.