Molecular Beam Epitaxy of Wurtzite (Ga,Mn)N Films on Sapphire(0001) Showing the Ferromagnetic Behaviour at Room Temperature

Wurtzite (Ga,Mn)N films showing ferromagnetic behaviour at room temperature were successfully grown on sapphire(0001) substrates by molecular beam epitaxy using ammonia as nitrogen source. Magnetization measurements were carried out by a superconducting quantum interference device at the temperatures between 1.8K and 300K with magnetic field applied parallel to the film plane up to 7T. The magnetic-field dependence of magnetization of a (Ga,Mn)N film at 300K were ferromagnetic, while a GaN film showed Pauli paramagnetism like behaviour. The Curie temperatures of a (Ga,Mn)N film was estimated as 940K.Comment: 5 page

Ab-initio Molecular Dynamics Simulation of Li Insertion in C_<60>

Complexes composed of fullerenes and metal elements offer important examples as new nanomaterials in the field of materials design. In the collisions between C^-_ and Li^+ in plasma state, there is a possibility that the endohederal fullerene, Li@C_ is created as well as Li@C_ and so on. To study this phenomenon theoretically, we perform an all-electron mixed basis ab initio molecular dynamics simulation at 1, 000K which was developed by ourselves. When Li^+ with the kinetic energy ～5eV hits the center of a six-membered ring of C^-_, an endohedral complex, Li@C_ is created. This direcet insertion process is possible because the ionic radius of Li^+ is shorter then the radius of a six-membered ring. However, if either the kinetic energy is lower or the collision occurs off-center, the Li^+ ion stays outside and C_ is deformed by the shock

A Simple Screening of Flower Sensitivity to Ethylene in Several Ornamental Asteraceae Species

Generally, Asteraceae flowers such as chrysanthemums and gerberas, are low ethylene-sensitive and do not exhibit petal wilting and abscission. However, previous research found that the flowers of dahlia, an Asteraceae member belonging to the tribe Coreopsideae, are ethylene-sensitive and show abscission layer development in petal-ovary boundaries. In this study, we investigated the ethylene sensitivity of 17 ornamental Asteraceae species belonging to different tribes by measuring the petal drawing resistance and vase life after 1-3 μL·L-1 ethylene exposure for 20 h. Although more than half of the tested species did not respond to ethylene, several species showed ethylene-sensitive petal wilting and abscission of fresh ray florets. Ethylene-sensitive petal wilting occurred in only two species (Calendula officinalis L. and Osteospermum L.) of the tribe Calenduleae, while ethylene-sensitive petal abscission occurred mainly in six species (Bidens ferulifolia D.C., Coreopsis lanceolata L., Cosmos atrosanguineus (Hook) Voss., Cosmos bipinnatus Cav., Cosmos sulphureus Cav. and Dahlia Cav.) of tribe Coreopsideae and one species (Helianthus annuus L.) of the tribe Heliantheae. In these species, abscission petals maintained their turgidity, and this process could be detected by measuring the petal drawing resistance of the ray florets. The reduction in petal drawing resistance, associated with abscission layer development in the petal-ovary boundaries, was observed only in these ethylene-sensitive species. The results of this study suggest that the ethylene sensitivity and petal senescing patterns in Asteraceae flowers may be associated with the phylogenetic classification at the tribe level

Effects of Deflowering and Defoliating on the Postharvest Characteristics of Individual Organs in Cut Dahlias

Cut dahlia (Dahlia Cav.) flowers have recently become popular, but their marketability has been limited due to their poor vase life. The purposes of this study were to clarify the roles of leaves and inflorescences in the senescence of cut dahlias and to discuss the sink-source relationship between vegetative organs and inflorescences. The leaf life was maintained much longer (16.7 days) than the inflorescence life (7.4 days). The inflorescence life was not affected by removal of leaves, while leaf life was prolonged (19.6 days) by removal of inflorescences. Sucrose, glucose, fructose and small quantities of myo-inositol were detected in florets, and in addition to these sugars, nystose and 1-kestose were detected in stems and leaves. Total sugar levels of the middle florets (14.5 mg·g⁻¹ FW on day 0) declined rapidly before their senescence. Total sugar levels of leaves (20.5 mg·g⁻¹ FW on day 0) and stems (19.0–22.5 mg·g⁻¹ FW on day 0) also decreased gradually during the postharvest period, but the levels decreased more slowly in deflowered cut stems. Sugar leakage from stem bases into vase water occurred during the initial few days. Removal of inflorescences increased sugar leakage significantly and promoted callus formation on the stem base. From these results, the inflorescence is considered to be a strong sink for carbohydrates, and stems and leaves serve as source organs. Heat girdling applied to the flower necks and petioles, also increased sugar concentrations of stem bases, thus resulting in higher sugar leakage and callus formation, although both heat girdling treatments shortened the leaf life. The sharp decrease in sugar levels of florets and an insufficient sugar supply are considered to be responsible for the short vase life of cut dahlias. It is suggested that these effects might be partly due to the blockage of sugar flows into petals through abscission layer development in the petal-ovary boundaries. Based on these results, we illustrate the senescing process of cut dahlia flowers in relation to sugar dynamism

Leukocyte activation by (1→3)-β-D glucans

We studied the activities of several kinds of β-glucans, including sonifilan, grifolan, Sclerotinia sclerotiorum glucan, laminarin and zymosan, on macrophages. Preculture of macrophages with inactive β-glucans rendered the cells unresponsive to subsequent stimulation with grifolan, suggesting a specific pathway in the β-glucan structure. The importance of protein C and phosphorylation of mitogen-activated protein kinase was demonstrated in the activation with grifolan or zymosan. Immunoprecipitation of complement receptor (CR3), coprecipitated other proteins carrying phosphotyrosine residues in stimulation with grifolan. These data suggest that protein kinase C and tyrosine kinases are essential for signal transduction, and that CR3 might participate in the activation through interaction with other intracellular proteins