Crystallization kinetics and phase transformation characteristics of μ- or α-cordierite seeded gels were compared with those of unseeded monophasic gels. The α-cordierite seeding modified the sequence of phase transformation and lowered the temperature of α-cordierite formation from amorphous gel by ∽150 °C. The μ-seeded transformation was characterized by 3-dimensional isotropic growth with essentially zero activation energy for the nucleation step. Combining the nucleation theory with the transition state theory, we have separately estimated the activation free energy of nucleation and that of growth step in the crystallization of amorphous cordierite gel. The estimated activation free energies showed that the crystallization of unseeded cordierite gel is mainly growth controlled.

Based on the electrokinetic properties of aqueous silica, boehmite, and ZrO, dispersions, cordierite-ZrO, composites were fabricated by a mixed colloidal processing route. The fabricated composite was characterized by a dense and homogeneous microstructure and by a uniform spatial distribution of submicrometer-sized tetragonal ZrO, particles throughout the matrix. Increasing ZrO, content enhanced densification and resulted in a full density composite at 20 wt% ZrO,. Fracture toughness was also increased with increasing ZrO, content. The enhanced toughening was partly attributed to the martensitic transformation of the dispersed tetragonal ZrO, particles in a cordierite matrix. The formation of zircon was suppressed by suitably adjusting the heating schedule during sintering.

Effects of the scale of precursor mixing on densification behaviors and phase-transformation kinetics of multicomponent aluminosilicate gels were examined using cordierite gels prepared by two different processing routes: a monophasic (single phase) gel having molecular homogeneity, and a triphasic gel in which constitutive precursor phases are uniformly mixed in a nanometer scale (-50 nm). In the case of the monophasic cordierite gel, homogeneous molecular-scale mixing of precursors induces a direction formation of fi -cordierite without a preceding crystallization, and the densification stops at the onset of crystallization to /ii-cordierite at 960 °C. On the other hand, the densification of triphasic cordierite gel was not affected by the crystallization of intermediate spinel phase at 700 °C. The triphasic gel continues to densify until amorphous silica matrix crystallizes to quartz at 1180 °C. The enhanced densification observed in the triphasic gel was attributed to the retarded crystallization of amorphous silica component caused by the increase in diffusion distances.

We present a novel approach to the fabrication of advanced polymeric nanocomposite hydrogels from polyacrylamide (PAAm) by incorporation of graphene-silver-polyethylenedioxythiophene-polystyrene sulfonate (rGO-Ag-PEDOT/PSS) by photopolymerization method. Infrared spectroscopy was employed to characterize the structure of the hydrogels. The internal network structure of nanocomposite hydrogels was investigated by scanning electron microscope. Swelling, deswelling, and mechanical properties of the hydrogels were investigated. The compressive strength of nanocomposite hydrogels reaches maximum of 1.71 MPa when the ratio of rGO-Ag-PEDOT/PSS to PAAm was 0.3 wt%, which is 1.57 times higher than that of PAAm hydrogels (1.09 MPa). The electrical conductivity of the PAAm-rGO-Ag-PEDOT/PSS hydrogel was found to be 3.91 × 10 À5 S cm À1 .

Jealousy may have evolved to protect valuable social bonds from interlopers, but some researchers have suggested that it is linked to self-awareness and theory of mind, leading to claims that it is unique to humans. We presented dogs ( N = 18; 11 females; age: M = 4.6 years, SD = 1.9) with situations in which they could observe an out-of-sight social interaction between their owner and a fake dog or between their owner and a fleece cylinder. We found evidence for three signatures of jealous behavior in dogs: (a) Jealousy emerged only when the dog’s owner interacted with a perceived social rival, (b) it occurred as a consequence of that interaction and not because of the mere presence of a conspecific, and (c) it emerged even for an out-of-sight interaction between the dog’s owner and a social rival. These results support claims that dogs display jealous behavior, and they provide the first evidence that dogs can mentally represent jealousy-inducing social interactions.

Based on the electrokinetic properties of aqueous silica, boehmite, and ZrO2 dispersions, cordierite-ZrO2 composites were fabricated by the multiphasic sol-gel (or nanometer-scale sol mixing) route. The average particle sizes of boehmite and ZrO2 used in this study are 70 nm and 40 nm, respectively. The fabricated composites were characterized by a dense and homogeneous microstructure and by a uniform spatial distribution of submicron-sized tetragonal ZrO2 particles (200 nm) throughout the matrix. The microstructure of the matrix was represented by small-sized grains (< 400 nm) with a highly uniform grain-size distribution. The enhanced fracture toughness with increasing ZrO2 content was partly attributed to the martensitic t → m transformation. The formation of detrimental zircon (ZrSiO4) was avoided by suitably adjusting the heating schedule during sintering.

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