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The high-temperature ferromagnetism in Co-doped ZnO samples fabricated by the standard solid-state reaction method is reported. Additional Cu doping into bulk Zn 0.98 Co 0.02 O is essential to achieve room-temperature ferromagnetism. Structure and composition analyses revealed that cobalt is incorporated into the lattice structure, forming a solid solution instead of precipitates. In the case of Zn 0.97 Cu 0.01 Co 0.02 O, the coercive field measured by a vibrating sample magnetometer at room temperature is 60 Oe. The implication of the effect of Cu doping in bulk Zn 0.98 Co 0.02 O is also discussed.

Natural homologues of cobra cardiotoxins (CTXs) were classified into two structural subclasses of group I and II based on the amino acid sequence and circular dichroism analysis, but the exact differences in their three-dimensional structures and biological significance remain elusive. We show by circular dichroism, NMR spectroscopic, and X-ray crystallographic analyses of a newly purified group I CTX A6 from eastern Taiwan cobra (Naja atra) venoms that its loop I conformation adopts a type VIa turn with a cis peptide bond located between two proline residues of PPxY. A similar "banana-twisted" conformation can be observed in other group I CTXs and also in cyclolinopeptide A and its analogues. By binding to the membrane environment, group I CTX undergoes a conformational change to adopt a more extended hydrophobic domain with beta-sheet twisting closer to the one adopted by group II CTX. This result resolves a discrepancy in the CTX structural difference reported previously between solution as well as crystal state and shows that, in addition to the hydrophobicity, the exact loop I conformation also plays an important role in CTX-membrane interaction. Potential protein targets of group I CTXs after cell internalization are also discussed on the basis of the determined loop I conformation.

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Ferromagnetic Si1−xMnx was prepared by implanting B+ and Mn+ ions in sequence into p-type Si(100) at room temperature and post-annealing at 700–900 °C. Superparamagnetic nano-sized silicide precipitates, 10–27 at.% Mn, were found near the surface of all Si1−xMnx samples. Annealing at 800 °C or below leads to the formation of a thin Si(Mn) layer, with 1.1 at.% Mn, ∼180 nm beneath the surface, giving rise to ferromagnetism with a Curie temperature above 250 K. The high-temperature ferromagnetism is attributed to the indirect exchange mediated by localized carriers in the impurity states. The Mn content of 1–1.5 at.%, having been separately reported to show room-temperature ferromagnetism several times by different groups, seems meaningful for Si-based diluted magnetic semiconductors (DMS). Possible extensions of our work presented here are elucidated.

Papaya pulp is very perishable and has a short shelf life. Manually sliced papayas were treated with 0%, 0.25%, 0.5%, and 1% chitosan (non-micronized and micronized) aqueous solutions; placed into plastic trays, and over-wrapped with PVDC film and then stored at 4°C. Color, soluble solid content, water loss, and total plate count of samples were evaluated. Chitosan coating had the ability to maintain the lightness of the sliced papayas. The a* values of the micronized chitosan-coated sliced papayas were significantly lower than those of the-coated. The sliced papayas that had been treated with 1% MC had a higher total soluble solid content and lower b* value after four days of storage. Also, the chitosan coating on the sliced papaya effectively retarded water loss and inhibited the growth of microorganisms. The results reveal that applying a chitosan coating effectively maintained the quality attributes and prolonged the shelf life of the sliced papayas.

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