Theoretical study on ferroelectric nitrides with super-wurtzite structures for solar energy conversion applications.

Polarized structured nitride semiconductors are attractive due to their unique and environment-friendly electronic properties. The stability, ferroelectricity and photocatalytic and photovoltaic properties of super-wurtzite Mg2XN3 (X = Bi, Mo, Nb, Sb, Ta, Tc and W) were determined based on first principles calculations in this study. The calculated results indicate that Mg2XN3 (X = Sb, Ta, Bi and Nb) are stable polar nitrides by phonon frequencies, elastic coefficients and ferroelectric analysis. Mg2XN3 (X = Sb, Ta and Nb) with large ferroelectric polarization strength could absorb ultraviolet light to promote photocatalytic water splitting for hydrogen production. Mg2BiN3 is a new excellent photovoltaic candidate due to its ideal energy band, high electron mobility, high absorption coefficient and large ferroelectric polarization strength.

A flavonoid 8-C-glycoside and a triterpenoid cinnamate from Nervilia fordii.

One new flavonoid glycoside (1) and one new triterpenoid cinnamate (2) were isolated from Nervilia fordii. The structures of 1 and 2 were determined by extensive NMR and HRESIMS to be 7-O-ß-d-glucopyranosylapigenin-8-C-ß-d-glucopyranosyl-(1 â†’ 2)-ß-d-glucopyranoside and 24(S/ß)-dihydrocycloeucalenol-3-(Z)-p-hydroxycinnamate, respectively.

Three new cycloartane glycosides from Nervilia fordii.

From the water-soluble extract of the aerial part of herbal plant Nervilia fordii, three new cycloartane glycosides, named as nervisides A (1), B (2), and C (3), were isolated. Their structures were elucidated through a combination of spectroscopic analysis and hydrolysis. At the same time, the new compounds were tested for their cytotoxicities in vitro against human tumor cell lines (CNE, Hep-2, and HepG2) using MTT method.