Molecular identification of Achyranthis Bidentatae Radix by using DNA barcoding.

Achyranthis Bidentatae Radix has a long history in China as a commonly used herb that can be used to treat various diseases, including those related to the liver, muscles, bones, and kidneys. Recently, an increase in the number of adulterants has been reported, which affects the clinical safety of Achyranthis Bidentatae Radix. To identify adulterants of Achyranthis Bidentatae Radix, we collected samples from major regions and conducted an in-depth genetic comparison of the herb and its commonly used adulterants. We amplified and sequenced three genomic regions, internal transcribed spacer (ITS), psbA-trnH, and internal transcribed spacer 2 (ITS2), to confirm whether ITS2 is a suitable identifier for Achyranthis Bidentatae Radix. Results showed that the ITS2 sequence length of Achyranthis Bidentatae Radix was 199 bp, with no variation between samples. The inter-specific genetic distance of ITS2 between Achyranthis Bidentatae Radix and its adulterants was 0.390. Neighbor-joining trees showed that Achyranthis Bidentatae Radix and its adulterants are easily differentiated by monophyly. In conclusion, ITS2 regions accurately and effectively distinguished between Achyranthis Bidentatae Radix and its adulterants.

Vibrational lifetimes and frequency-gap law of hydrogen bending modes in semiconductors.

Vibrational lifetimes of hydrogen and deuterium related bending modes in semiconductors are measured by transient bleaching spectroscopy and high-resolution infrared absorption spectroscopy. We find that the vibrational lifetimes follow a universal frequency-gap law; i.e., the decay time increases exponentially with increasing decay order, with values ranging from 1 ps for a one-phonon process to 265 ps for a four-phonon process. The temperature dependence of the lifetime shows that the bending mode decays by lowest-order multiphonon process. Our results provide new insights into vibrational decay and the giant isotope effect of hydrogen in semiconductor systems.