The spin-orbit-phonon coupling and crystalline elasticity of LaCoO3 perovskite.

Based on an integrated study of magnetic susceptibility, specific heat, and thermal expansion of single-crystal LaCoO3 free from cobalt and oxygen vacancies, two narrow spin gaps are identified before and after the phonon softening of gap size ΔE ∼ 0.5 meV in a CoO6-octahedral crystal electric field (CEF) and the thermally activated spin gap Q ∼ 25 meV, respectively. Significant excitation of Co3+ spins from a low-spin (LS) to a high-spin (HS) state is confirmed by the thermal activation behavior of spin susceptibility χ S of energy gap Q ∼ 25 meV, which follows a two-level Boltzmann distribution to saturate at a level of 50% LS/50% HS statistically above ∼200 K, without the inclusion of a postulated intermediate spin (IS) state. A threefold increase in the thermal expansion; coefficient (α) across the same temperature range as that of thermally activated HS population growth is identified, which implies the non-trivial spin-orbit-phonon coupling caused the bond length of Co3+(LS↔HS)-O fluctuation and the local lattice distortion. The unusually narrow gap of ΔE ∼ 0.5 meV for the CoO6 octahedral CEF between eg-t2g indicates a more isotropic negative charge distribution within the octahedral CEF environment, which is verified by the Electron Energy Loss Spectroscopy (EELS) study to show nontrivial La-O covalency.

An outbreak of coxsackievirus A16 infection: comparison with other enteroviruses in a preschool in Taipei.

BACKGROUND/PURPOSE: The transmission rate of enteroviruses in young children remains unclear. Therefore, we carried out active surveillance in preschool children to investigate the transmission rate and clinical manifestation of enteroviruses. METHODS: From September 2006 to December 2008, we monitored infectious diseases in children 2(-3 years of age) in a preschool in Taipei. If any child had a febrile illness or symptoms/signs of enteroviral infection [e.g. herpangina or hand-foot-and-mouth disease (HFMD)], we performed viral isolation and enterovirus polymerase chain reaction. VP1 sequencing was performed to define their serotypes. We also collected clinical data and analyzed transmission rates. RESULTS: There were eight episodes of enterovirus infection during the study period. The serotypes included coxsackievirus A4 (CA4), CA2 and CA16. The transmission rates of CA4 and CA2 among children in same class were 26% and 35%, respectively. Between November 28 and December 12, 2008, 13/21 (61.9%) children contracted herpangina and/or HFMD. The average age was 2.82 (range, 2.43-3.39) years. CA16 was detected in 10/13 (76.9%) of the throat swabs by polymerase chain reaction VP1 genotyping. Compared with previous CA2 and CA4 outbreaks, CA16 had a significantly higher transmission rate (p = 0.035) and resulted in more cases of HFMD (p < 0.001). The transmission duration of coxsackie A viruses within the same class ranged from 12 to 40 days. CONCLUSION: Compared with CA2 and CA4, CA16 infections resulted in more cases of HFMD and had significantly higher transmission rates in preschoolers.