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Final-stage sintering has been investigated in ultrahighpurity Al 2 O 3 and Al 2 O 3 that has been doped individually with 1000 ppm of yttrium and 1000 ppm of lanthanum. In the undoped and doped materials, the dominant densification mechanism is consistent with grain-boundary diffusion. Doping with yttrium and lanthanum decreases the densification rate by a factor of ∼11 and 21, respectively. It is postulated that these large rare-earth cations, which segregate strongly to the grain boundaries in Al 2 O 3 , block the diffusion of ions along grain boundaries, leading to reduced grain-boundary diffusivity and decreased densification rate. In addition, doping with yttrium and lanthanum decreases grain growth during sintering. In the undoped Al 2 O 3 , surface-diffusion-controlled pore drag governs grain growth; in the doped materials, no grain-growth mechanism could be unambiguously identified. Overall, yttrium and lanthanum decreases the coarsening rate, relative to the densification rate, and, hence, shifted the grainsize-density trajectory to higher density for a given grain size. It is believed that the effect of the additives is linked strongly to their segregation to the Al 2 O 3 grain boundaries.

A series of novel pyrazole oxime derivatives containing a 2-chloro-5-thiazolyl moiety were synthesized. Their structures were confirmed by (1)H NMR, (13)C NMR, and elemental analysis. The preliminary bioassays showed that all of the title compounds had low acaricidal activity against Tetranychus cinnabarinus . However, most of them exhibited excellent insecticidal activity against Aphis medicagini at the dosage of 0.5 mg/mL, and some compounds still showed good insecticidal activity against A. medicagini even at the dosage of 0.2 mg/mL. Meanwhile, some title compounds displayed fungicidal and plant growth regulatory activities.

a-Haloacetylferrocene and a-triazolylacetylferrocene have been prepared from acetylferrocene and they have proved to be useful building blocks for the synthesis of ferrocenyl propenone. Two new types of ferrocenyl vinyl triazole compound, (Z,E)-ferrocenyl-[1-(1,2,4-triazol-1-yl)-2-phenyl]-vinylones, have been synthesized and their structures characterized by crystal X-ray diffraction analysis. It has been shown for the first time that ferrocene, as an organometallic compound, has been introduced into bioactive triazole compounds in search of potent bioactive substances. Their biological activities are also discussed.