Atomically precise photothermal nanomachines.

Interfacing molecular machines to inorganic nanoparticles can, in principle, lead to hybrid nanomachines with extended functions. Here we demonstrate a ligand engineering approach to develop atomically precise hybrid nanomachines by interfacing gold nanoclusters with tetraphenylethylene molecular rotors. When gold nanoclusters are irradiated with near-infrared light, the rotation of surface-decorated tetraphenylethylene moieties actively dissipates the absorbed energy to sustain the photothermal nanomachine with an intact structure and steady efficiency. Solid-state nuclear magnetic resonance and femtosecond transient absorption spectroscopy reveal that the photogenerated hot electrons are rapidly cooled down within picoseconds via electron-phonon coupling in the nanomachine. We find that the nanomachine remains structurally and functionally intact in mammalian cells and in vivo. A single dose of near-infrared irradiation can effectively ablate tumours without recurrence in tumour-bearing mice, which shows promise in the development of nanomachine-based theranostics.

[Distribution Characteristics of Soil Phosphorus Forms and Phosphatase Activity at Different Altitudes in the Soil of Water-Level-Fluctuation Zone in Pengxi River, Three Gorges Reservoir].

Phosphatases play important roles in converting organic phosphorus into inorganic phosphorus in soil. However, studies from this perspective on the water-level-fluctuation zone (WLFZ) of the Three Gorges Reservoir are limited. In this study, phosphatase activity and the forms of phosphorus were analyzed. Soil samples were collected in the river basin of the Penxi River in the WLFZ during a drying period. The correlation between phosphatase activity and phosphorus forms and the impacts of phosphatase activity on the phosphorus forms were analyzed. The results showed that the contents of H2O-Pi, NaHCO3-Pi, and NaOH-Pi in the soils of the WLFZ were higher than those in the soils by the river. In addition, a higher altitude resulted in higher contents of bio-enzymatically hydrolysable phosphorus and NaOH-Po. Furthermore, redundancy analysis (RDA) showed that the contents of organic matter and amorphous Fe and Mn were the main factors affecting soil organic phosphorus forms. The average activities of acid phosphomonoesterase (ACP), alkaline phosphomonoesterase (ALP), phosphodiesterase (PDE) (all in p-NP), and phytase (PAE) (in P) in the soils of the WLFZ were 1.40, 2.60, 0.44, and 11.43 µmol·(g·h)-1, respectively. Moreover, the activities of different phosphatases increased with altitude. Soil plant biomass and microbial biomass were important reasons for the difference in spatial distribution of phosphatase activity in the soil of the WLFZ. Phosphatase activities were significantly positively correlated with the contents of organic phosphorus forms but negatively correlated with the content of bioavailable phosphorus. A higher soil phosphatase activity and a lower content of bioavailable phosphorus were usually detected in soil samples taken at a higher altitude. In the early stage of flooding, phosphatase converted organic phosphorus into inorganic phosphorus at a relatively high rate, and the risk of phosphorus release to the overlying water body was also high. This study contributed to a comprehensive understanding of the geochemical cycle of soil phosphorus in the soil of the WLFZ.

Electrospray/VUV single-photon ionization mass spectrometry for the analysis of organic compounds.

For the comprehensive analysis of organic compounds, especially thermal labile and nonpolar compounds, an electrospray/vacuum ultraviolet (VUV) single-photon ionization (ES-SPI) method was developed. The fine droplets of the sample solution from the electrospray process were directed through a quartz capillary and two skimmers to form a molecular beam into a high vacuum ionization chamber. The neutral sample molecules were softly ionized with tunable VUV light and analyzed with a reflection time-of-flight mass spectrometer (RTOF-MS). The ionization energy (IE) and appearance onsets of fragments were obtained based on the photoionization efficiency (PIE) spectrum. The isomers can also be distinguished. With this new method, clean (fragment-free) mass spectra of nonpolar compounds, such as benzene, cyclohexane, and some thermal labile solid compounds (triphenylamine, thioacetamide, and urea) have been obtained without any tedious pretreatment. The components of complex mixtures (gasoline and kerosene) can be identified. Furthermore, quantitative analysis of the components can be obtained based on photoionization cross section data. This method may be used for quantitative analysis of small biomolecules and natural products.