ALBERT

Description: This study explored the relative roles of climate and phylogenetic background in driving morphometric trait variation in 10 spruce taxa in China. The study further addressed the hypothesis that these variations are consistent with species turnover on climatic gradients. Nine morphometric traits of leaves, seed cones, and seeds for the 10 studied spruce taxa were measured at 504 sites. These data were analyzed in combination with species DNA sequences from NCBI GenBank. We detected the effects of phylogeny and climate through trait-variation-based K statistics and phylogenetic eigenvector regression (PVR) analyses. Multivariate analyses were performed to detect trait variation along climatic gradients with species replacement. The estimated K -values for the nine studied morphometric traits ranged from 0.19 to 0.68, and the studied environmental variables explained 39–83% of the total trait variation. Trait variation tended to be determined largely by a temperature gradient varying from wet-cool climates to dry-warm summers and, additionally, by a moisture gradient. As the climate became wetter and cooler, spruce species tended to be replaced by other spruces with smaller needle leaves and seeds but larger cones and seed scales. A regression analysis showed that spruce species tended to be successively replaced by other species, along the gradient, although the trends observed within species were not necessarily consistent with the overall trend. The climatically driven replacement of the spruces in question could be well indicated by the between-species variation in morphometric traits that carry lower phylogenetic signal. Between-species variation in these traits is driven primarily by climatic factors. These species demonstrate a narrower ecological amplitude in temperature but wider ranges on the moisture gradient. Previous studies have characterized the overall influence of climate on spruce distribution and trait variation. However, most of the previous studies of these topics in spruce have focused on one or a few species, and little is known about the relationship between trait variation and species turnover for a wide array of spruce species at large scales, and even less has been clarified about relative roles of climate and phylogenetic background in driving morphometric trait variation. Using data from field surveys in the spruce forests across China, we showed that the climatically driven replacement of the spruces in question could be well indicated by the between-species variation in morphometric traits that carry weak phylogenetic signals but strong climatic signals and demonstrate a narrower temperature amplitude but wider ranges on the moisture gradient.

Description: The Ag 2 Mo 2 O 7 and Ag 6 Mo 10 O 33 ceramics for ultra-low temperature co-fired ceramic application were prepared by the solid-state reaction route. The optimized densification temperatures of Ag 2 Mo 2 O 7 and Ag 6 Mo 10 O 33 are 460°C and 500°C, respectively. The phase structures and microstructures of these ceramics were systematically studied. The Ag 2 Mo 2 O 7 ceramic sintered at 460°C/4 h exhibits excellent microwave dielectric properties with ε r =13.3, Q×f =25 300 GHz and τ f =−142 ppm/°C at 9.25 GHz. The Ag 6 Mo 10 O 33 ceramic sintered at 500°C/4 h shows the microwave dielectric properties with ε r =14.0, Q×f =8500 GHz and τ f =−50 ppm/°C at 9.00 GHz. Moreover, when Ag 2 Mo 2 O 7 samples are sintered at ultra-low sintering temperatures of 420°C-490°C, the Q×f values of them are all above 20 000 GHz. Besides, the Ag 2 Mo 2 O 7 ceramic does not react with silver powder or aluminum powder. The variation of relative permittivity, resonant frequency, and Q×f values as a function of operating temperature has been also studied. All the results indicate that the Ag 2 Mo 2 O 7 ceramic is a good candidate for ultra-low temperature co-fired microwave devices.