The exaggerated grain growth, anisotropic crystallite morphology, and thermal expansion are the main reasons for the microcracking of sintered TiB2, wherein grain coarsening and anisotropic crystallite morphology are believed to be controlled by the surface stabilities of TiB2. To deeply understand the grain growth mechanism, the anisotropic stability and bonding features of TiB2 surfaces, including $\left( {11\bar 20} \right)$ , two types of (0001), and three types of $\left( {10\bar 10} \right)$ , are investigated by first-principles calculations. By employing the two-region modeling method, surface energies are calculated and the $\left( {11\bar 20} \right)$ surface is found to be more stable than (0001) and $\left( {10\bar 10} \right)$ surfaces. Hexagonal plate-like grain morphology is predicted. The different bonding conditions of surface Ti and B atoms contribute to the difference of surface structure relaxation between surfaces with Ti- and B-termination, which lead the B-terminated ones to be more stable. It is also found that the surface energies of TiB2 are much higher than those of ZrB2 with a similar structure, which may be responsible for the easy coarsening of TiB2.

Novel porous Yb3Al5O12 ceramics are successfully fabricated via a green and simple foam-gelcasting approach. Using a nontoxic water-soluble copolymer of isobutylene and maleic anhydride (Isobam), together with a surfactant EMAL TD (Surf-E), 50 vol% solid loading Yb3Al5O12 aqueous ceramic slurries are prepared. Thanks to the small contents of organic additives (0.4 wt% Isobam and 1 vol% Surf-E) added, low linear shrinkage (∼13.9%), and mass loss (∼2.21 wt%) are obtained after pressureless sintering of gelcasted green body at 1600 °C for 4 h under an air atmosphere. Furthermore, porous Yb3Al5O12 ceramics with controlled porosity and spherical-like cells possess excellent structural and shape stability. The flexural strength and compressive strength of the as-prepared porous Yb3Al5O12 ceramics with a relative density of 20% remain as high as 6.3 and 19.7 MPa, respectively, and the gas permeability can be tuned between 4.3 × 10−13 and 7.8 × 10−11 m2 with exponentially increasing porosity from 58% to 84%.

In this contribution, the structural, mechanical, and thermal properties of MSiO4 have been investigated theoretically and the anisotropy of elastic properties has been discussed in detail. The heterogeneous bonding nature was revealed from density functional theory computations and chemical bond theory (CBT). The Young's modulus and shear modulus of MSiO4 were anisotropic and the anisotropy on different planes was quite different. The thermal expansion coefficients of MSiO4 estimated from CBT were 5.1 × 10−6 and 4.4 × 10−6 K−1 for ZrSiO4 and HfSiO4, respectively. These results were quite consistent with the experiments. The temperature dependent thermal conductivities of MSiO4 were estimated from Slack's model, the minimum thermal conductivity was predicted to be 1.54 and 1.24 W m−1 K−1 for ZrSiO4 and HfSiO4, respectively. Our theoretical results show that MSiO4 are excellent thermal barrier materials with good tolerance to withstand the mechanical damage.

In this article, a comprehensive investigation on the thermal properties of Yb3Al5O12 is conducted, including Debye temperature, thermal expansion coefficient (TEC), thermal diffusivity, heat capacity, and thermal conductivity. The calculated Debye temperature of Yb3Al5O12 from the measured elastic properties is 625 K. The linear and volumetric thermal expansions of Yb3Al5O12 from 298 to 1273 K are (7.83 ± 0.14) × 10−6 and (23.74 ± 0.42) × 10−6 K−1, respectively. The linear TEC of the polycrystalline bulk Yb3Al5O12 determined by dilatometer is (8.22 ± 0.3) × 10−6 K−1. The measured thermal conductivities of Yb3Al5O12 are 4.67 and 2.05 W (m K)−1, respectively, at 300 and 1400 K. The estimated minimum thermal conductivity, κmin, is 1.22 W (m K)−1. The high temperature thermal conductivity is close to the evaluated κmin, which is lower than most commonly used thermal barrier coating (TBC) material such as Y2O3-stabilized-ZrO2 (YSZ). The unique combination of these properties renders Yb3Al5O12 being a very promising candidate material for TBC.

Ytterbium monosilicate (Yb2SiO5) is a promising candidate for environmental barrier coating. However, its mechanical and thermal properties are not well understood. In this work, the structural, mechanical, and thermal properties of Yb2SiO5 are studied by combining density functional theory and chemical bond theory calculations. Based on the calculated equilibrium crystal structure, heterogeneous bonding nature and distortion of the structure are revealed. Meanwhile, the full set of elastic constants, polycrystalline mechanical properties, and elastic anisotropy of Yb2SiO5 are presented. In addition, the minimum thermal conductivity of Yb2SiO5 was determined to be 0.74 W m−1 K−1. The theoretical results highlight the potential application of Yb2SiO5 in a thermal and environmental barrier coating.

Dietary protein restriction is one major therapy in chronic kidney disease (CKD), and ketoacids have been evaluated in CKD patients during restricted-protein diets. The objective of the present study was to compare the efficacy of a low-protein diet supplemented with ketoacids (LPD+KA) and a low-protein diet alone (LPD) in halting the development of renal lesions in CKD. 5/6 Nephrectomy Sprague–Dawley rats were randomly divided into three groups, and fed with either 22 % protein (normal-protein diet; NPD), 6 % protein (LPD) or 5 % protein plus 1 % ketoacids (LPD+KA) for 24 weeks. Sham-operated rats were used as controls. Each 5/6 nephrectomy group included fifteen rats and the control group included twelve rats. Proteinuria, decreased renal function, glomerular sclerosis and tubulointerstitial fibrosis were found in the remnant kidneys of the NPD group. Protein restriction ameliorated these changes, and the effect was more obvious in the LPD+KA group after 5/6 nephrectomy. Lower body weight and serum albumin levels were found in the LPD group, indicating protein malnutrition. Lipid and protein oxidative products were significantly increased in the LPD group compared with the LPD+KA group. These findings indicate that a LPD supplemented with ketoacids is more effective than a LPD alone in protecting the function of remnant kidneys from progressive injury, which may be mediated by ketoacids ameliorating protein malnutrition and oxidative stress injury in remnant kidney tissue.