Femtosecond Time-Resolved Neighbor Roles in the Fragmentation Dynamics of Molecules in a Dimer.

How the neighbor effect plays its role in the fragmentation of molecular clusters attracts great attention for physicists and chemists. Here, we study this effect in the fragmentation of N_{2}O dimer by performing three-body coincidence measurements on the femtosecond timescale. Rotations of bound N_{2}O^{+} triggered by neutral or ionic neighbors are tracked. The forbidden dissociation path between B^{2}Π and ^{4}Π is opened by the spin-exchange effect due to the existence of neighbor ions, leading to a new channel of N_{2}O^{+}→NO+N^{+} originating from B^{2}Π. The formation and dissociation of the metastable product N_{3}O_{2}^{+} from two ion-molecule reaction channels are tracked in real time, and the corresponding trajectories are captured. Our results demonstrate a significant and promising step towards the understanding of neighbor roles in the reactions within clusters.

What's the choice for goji: Lycium barbarum L. or L. chinense Mill.?

ETHNOPHARMACOLOGICAL RELEVANCE: For over one millennium, goji berries have been used traditionally as food and medicine in eastern Asia. In recent decades, it has become increasingly popular globally. However, the biocultural development of goji is poorly known. The botanical origin of goji is controversial: in many but not all modern regional or international quality standards, L. barbarum is accepted exclusively as the botanical origin of goji. AIM OF THE STUDY: Focusing on historical, biogeographical, botanical, phytochemical and pharmacological data, the overarching aim is to understand the biological origin of goji's historical uses, as well as whether the two species can be used interchangeably. MATERIALS AND METHODS: The taxonomic literature on L. barbarum and L. chinense were analysed, followed by a study of botanical specimens and fieldwork. Historical herbals and gazetteers were employed to define the historical producing areas and medical properties of goji. An identification of the species used in history was carried out. In a final step the phytochemical and pharmacological literature on the species was compared. RESULTS AND DISCUSSION: Due to their morphological similarity and different accessibility, fruits of both L. barbarum and L. chinense have been used interchangeably as food and medicine at least since 682 CE. While the fruit of L. barbarum was recognized to be superior in quality, the fruit of L. chinense was commonly used as an equivalent because of its easier accessibility. Cultivation of L. barbarum in China since 1960s improved its availability, which likely lead to its exclusive use as source of goji in China. The long-term safe use with no reported major safety concerns supports that these two species both are useful sources for medicinal Lycium. CONCLUSIONS: Medicinal plants had been used traditionally long before they were named in scientific nomenclature system. Therefore, the understanding of traditional herbal knowledge and the adequate use of those traditional medicines require a reliable identification based on archival records. This study developed an approach for the identification of species used historically, with an integrated analysis of specimens, historical herbals, and national gazetteers. Additionally, their different chemical profiles and pharmacological activities indicate that they should not be used interchangeably. Further scientific evidence is required for their safe and effective use.

Preconcentration of nickel and cadmium by TiO2 nanotubes as solid-phase extraction adsorbents coupled with flame atomic absorption spectrometry.

TiO(2) nanotubes, a new nanomaterial, are often used in the photocatalysis. Due to its relatively large specific surface areas it should have a higher enrichment capacity. However, very few applications in the enrichment of pollutants were found. This paper described a new procedure to investigate the trapping power of TiO(2) nanotubes with cadmium and nickel in water samples as the model analytes and flame atomic absorption spectrometry for the analysis. The possible parameters influencing the enrichment were optimized. Under the optimal SPE conditions, the method detection limits and precisions (R.S.D., n=6) were 0.25 ngmL(-1) and 2.2% for cadmium, 1 ngmL(-1) and 2.6% for nickel, respectively. The established method has been successfully applied to analyze four realworld water samples, and satisfactory results were obtained. The spiked recoveries were in the range of 90.2-99.2% for them. All these indicated that TiO(2) nanotubes had great potential in environmental field.