Low-Temperature Synthesis of Anatase TiO2 Nanoparticles with Tunable Surface Charges for Enhancing Photocatalytic Activity

In this work, the positively or negatively charged anatase TiO[subscript 2] nanoparticles were synthesized via a low temperature precipitation-peptization process (LTPPP) in the presence of poly(ethyleneimine) (PEI) and poly(sodium4- styrenesulfonate) (PSS). X-ray diffraction (XRD) pattern and high-resolution transmission electron microscope (HRTEM) confirmed the anatase crystalline phase. The charges of the prepared TiO[subscript 2], PEI-TiO[subscript 2] and PSS-TiO[subscript 2] nanoparticles were investigated by zeta potentials. The results showed that the zeta potentials of PEI-TiO[subscript 2] nanoparticles can be tuned from +39.47 mV to +95.46 mV, and that of PSS-TiO[subscript 2] nanoparticles can be adjusted from −56.63 mV to −119.32 mV. In comparison with TiO[subscript 2], PSS-TiO[subscript 2] exhibited dramatic adsorption and degradation of dye molecules, while the PEI modified TiO[subscript 2] nanoparticles showed lower photocatalytic activity. The photocatalytic performances of these charged nanoparticles were elucidated by the results of UV-vis diffuse reflectance spectra (DRS) and the photoluminescence (PL) spectra, which indicated that the PSS-TiO[subscript 2] nanoparticles showed a lower recombination rate of electron-hole pairs than TiO[subscript 2] and PEI-TiO[subscript 2].National Natural Science Foundation (China) (21176005

A HY5-COL3-COL13 regulatory chain for controlling hypocotyl elongation in Arabidopsis

CONSTANS-LIKE (COL) family members are commonly implicated in light signal transduction during early photomorphogenesis. However, some of their functions remain unclear. Here, we propose a role for COL13 in hypocotyl elongation in Arabidopsis thaliana. We found that COL13 RNA accumulates at high levels in hypocotyls and that a disruption in the COL13 function via a T-DNA insertion or RNAi led to the formation of longer hypocotyls of Arabidopsis seedlings under red light. On the contrary, overexpression of COL13 resulted in the formation of shorter hypocotyls. Using various genetic, genomic, and biochemical assays, we proved that another COL protein, COL3, directly binds to the promoter of COL13, and the promoter region of COL3 was targeted by the transcription factor LONG HYPOCOTYL 5 (HY5), to form an HY5-COL3-COL13 regulatory chain for regulating hypocotyl elongation under red light. Additionally, further study demonstrated that COL13 interacts with COL3, and COL13 promotes the interaction between COL3 and CONSTITUTIVE PHOTOMORPHOGENIC1 (COP1), suggesting a possible COP1-dependent COL3-COL13 feedback pathway. Our results provide new information regarding the gene network in mediating hypocotyl elongation.China International Postdoctoral grant, Grant/Award Number: 20170053; National Natural Science Foundation of China, Grant/Award Numbers: 31572161, 31672188; Youth Foundation of the National Natural Science Foundation of China, Grant/Award Number: 30900107Peer reviewe

Comparative Characterization of Total Flavonol Glycosides and Terpene Lactones at Different Ages, from Different Cultivation Sources and Genders of Ginkgo biloba Leaves

The extract from Ginkgo biloba leaves has become a very popular plant medicine and herbal supplement for its potential benefit in alleviating symptoms associated with peripheral vascular disease, dementia, asthma and tinnitus. Most research on G. biloba leaves focus on the leaves collected in July and August from four to seven year-old trees, however a large number of leaves from fruit cultivars (trees older than 10 years) are ignored and become obsolete after fruit harvest season (November). In this paper, we expand the tree age range (from one to 300 years) and first comparatively analyze the total flavonol glycosides and terpene lactones at different ages, from different cultivation sources and genders of G. biloba leaves collected in November by using the validated HPLC-ELSD and HPLC-PDA methods. The results show that the contents of total terpene lactones and flavonol glycosides in the leaves of young ginkgo trees are higher than those in old trees, and they are higher in male trees than in female trees. Geographical factors appear to have a significant influence on the contents as well. These results will provide a good basis for the comprehensive utilization of G. biloba leaves, especially the leaves from fruit cultivars

UV-vis spectra of MB by the adsorption on (a)TiO₂, (b) PEI-TiO₂ and (c) PSS-TiO₂.

<p>UV-vis spectra of MB by the adsorption on (a)TiO₂, (b) PEI-TiO₂ and (c) PSS-TiO₂.</p

Schematic illustration of photocatalytic activity of (a) PSS-TiO₂, (b) PEI-TiO₂ nanoparticles for dye degradation under UV-light.

<p>Schematic illustration of photocatalytic activity of (a) PSS-TiO₂, (b) PEI-TiO₂ nanoparticles for dye degradation under UV-light.</p

Low-Temperature Synthesis of Anatase TiO_{2 - Figure 4} Nanoparticles with Tunable Surface Charges for Enhancing Photocatalytic Activity

<p>Zeta potential of pure TiO₂, PEI-TiO₂ (10%) and PSS-TiO₂ (10%) as a function of pH (a); zeta potential of PEI (1.0 mg/mL) solution as a function of pH (b); Particle size of the TiO₂, PEI-TiO₂ and PSS-TiO₂ nanoparticles at different pH (c); Transmittance changes of TiO₂ (pH 3), PEI-TiO₂ (pH 5) and PSS-TiO₂ (pH 11) suspensions over time (d).</p