Colloidal spirals in nematic liquid crystals.

One of the central experimental efforts in nematic colloids research aims to explore how the interplay between the geometry of particles along with the accompanying nematic director deformations and defects around them can provide a means of guiding particle self-assembly and controlling the structure of particle-induced defects. In this work, we design, fabricate, and disperse low-symmetry colloidal particles with shapes of spirals, double spirals, and triple spirals in a nematic fluid. These spiral-shaped particles, which are controlled by varying their surface functionalization to provide tangential or perpendicular boundary conditions of the nematic molecular alignment, are found inducing director distortions and defect configurations with non-chiral or chiral symmetry.

Two new 14-membered cyclopeptide alkaloids from Zizyphus xylopyra.

The phytochemical investigation of the bark of Zizyphus xylopyra resulted in the isolation of two new 14-membered ring cyclopeptide alkaloids, xylopyrine-G and xylopyrine H. Their structures have been established by chemical and spectral evidences.

Xylopyrine-F, a new cyclopeptide alkaloid from Zizyphus xylopyra.

A new 14-membered ring cyclopeptide alkaloid xylopyrine-F, together with known alkaloids nummularine-P and sativanine-H, has been isolated from the root bark of Zizyphus xylopyra and their structures were established by chemical and spectral evidences.

Xylopyrine-C, a new cyclopeptide alkaloid from Zizyphus xylopyra.

Xylopyrine-C, a new 14-membered ring cyclopeptide alkaloid, has been isolated from the root bark of Zizyphus xylopyra together with a known alkaloid scutianine-C, and their structures were established by chemical and spectral evidences.

Three new cyclopeptide alkaloids from Zizyphus species.

Two new cyclopeptide alkaloids, xylopyrine-D and xylopyrine-E, from Zizyphus xylopyra and a new alkaloid, jubanine-E, from Zizyphus jujuba have been isolated and their structures were established by chemical and spectral evidences.

Cyclopeptide alkaloids from Zizyphus sativa bark.

A new cyclopeptide alkaloid, sativanine-M (1), together with known alkaloid nummularine-P have been isolated from the stem bark of Zizyphus sativa and identified by spectral analysis.

Xylopyrine-A and xylopyrine-B, two new peptide alkaloids from Zizyphus xylopyra.

Two new 13-membered cyclopeptide alkaloids, xylopyrine-A and xylopyrine-B have been isolated from Zizyphus xylopyra, and their structures established by spectral and chemical evidences.