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Reversible upconversion luminescence modification based on photochromism has received considerable interest due to its potential applications in optical storage and high‐sensitivity optical switches. However, stimulation‐induced bleaching by an external thermal field is generally used for photochromism‐induced reversible upconversion luminescence modification, which limits its practical application. In this work, a gray BaMgSiO4:Yb3+,Tb3+ ceramic is prepared, exhibiting the photochromism from gray to pink color when stimulated by 254 nm light. Interestingly, the pink BaMgSiO4:Yb3+,Tb3+ ceramic can be bleached by either a 473 nm laser or thermal stimulation. The reversible change between gray and pink color exhibits excellent reproducibility over several cycles by alternating between 254 and 473 nm (or thermal) light stimulation. The influence of the reversible photochromism of the BaMgSiO4:Yb3+,Tb3+ ceramic on its upconversion luminescence is investigated. Reversible modification of the upconversion luminescence is demonstrated by alternating between 254 and 473 nm (or thermal) light stimulation. For reversible modulation of the upconversion luminescence, excellent reproducibility is realized after several cycles. As an example, the application of the BaMgSiO4:Yb3+,Tb3+ photochromic ceramic as an anti‐counterfeiting agent is described.

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AimsWe investigate native and introduced populations of Solanum rostratum, an annual, self-compatible plant that has been introduced around the globe. This study is the first to compare the genetic diversity of Solanum rostratum between native and introduced populations. We aim to (1) determine the level of genetic diversity across the studied regions; (2) explore the likely origins of invasive populations in China; and (3) investigate whether there is the evidence of multiple introductions into China.MethodsWe genotyped 329 individuals at 10 microsatellite loci to determine the levels of genetic diversity and to investigate population structure of native and introduced populations of S. rostratum. We studied five populations in each of three regions across two continents: Mexico, the U.S.A. and China.Important FindingsWe found the highest genetic diversity among Mexican populations of S. rostratum. Genetic diversity was significantly lower in Chinese and U.S.A. populations, but we found no regional difference in inbreeding coefficients (F IS) or population differentiation (F ST). Population structure analyses indicate that Chinese and U.S.A. populations are more closely related to each other than to sampled Mexican populations, revealing that introduced populations in China share an origin with the sampled U.S.A. populations. The distinctiveness between some introduced populations indicates multiple introductions of S. rostratum into China.

Bismuth ferrite (BiFeO3) powders were synthesized by a sol–gel process using polyvinyl alcohol (PVA) as a complexing agent. Thermogravimetric, Fourier transform infrared spectroscopy, X‐ray diffraction (XRD), and field‐emission scanning electron microscope techniques were used to characterize precursor and derived oxide powders. The effect of the ratios of positively charged valences to hydroxyl groups of PVA (Mn+/–OH) on the formation of BiFeO3 was investigated. XRD analysis showed that single‐phase and well‐crystallized BiFeO3 was obtained from the Mn+/–OH=2:1 precursor at a temperature as low as 400°C. For the precursor with Mn+/–OH=4:1, BiFeO3 formed only at the temperature of 600°C. With Mn+/–OH=1:1 and 1.5:1 precursor, pure BiFeO3 powder was not obtained. In present work, single‐phase BiFeO3 can be formed at lower temperature and less organics are required; furthermore, the process is simple and easy to control.

A facile sol-gel methodology based on the glycerol-gel reaction was used to prepare single-phase BiFeO 3 crystallites. The particle size and morphologies of BiFeO 3 crystallites were characterized by field-emission scanning electron microscope and transmission electron microscope. X-ray diffraction results indicated that single-phase and well-crystallized BiFeO 3 has been synthesized at the temperature as low as 4001C. In present work, single-phase BiFeO 3 can be formed at lower temperature and less organics is required, furthermore, the process is simple and easy to control.