Czochralski technique growth of pure and rare-earth-doped SrWO 4 crystals

Abstract Pure and rare-earth (Nd 3+ , Tm 3+ and Er 3+ )-doped strontium tungstates of good optical quality with sizes of about f20 mm  50 mm were grown successfully by the Czochralski technique. The (0 0 1) orientation was found to be the favorable direction for crystal growth. X-ray powder diffraction (XRD), differential thermal analysis (DTA) and differential scanning calorimeter (DSC) of pure strontium tungstate were measured. The concentrations of Nd 3+ , Tm 3+ and Er 3+ were measured and their segregation coefficients were also calculated. The absorption and emission spectra of rare-earth-doped crystals as a function of the s and p polarizations were presented and discussed. Favorable values of the absorption cross section centered at about 800 nm suggest that Nd 3+ -and Tm 3+ -doped strontium tungstates are promising candidates for laser diode (LD) pumping.

Occurrence of multi-mycotoxin in paddy rice in Guangdong Province

Objective To understand the contamination pattern of mycotoxin in paddy rice in the main rice-growing regions of Guangdong Province, and analyze the distribution difference of mycotoxin in different areas, so as to provide basis for the implementation of precise prevention and control measures. Methods A total of 120 paddy rice samples were collected from eight cities in the Pearl River Delta, northern, eastern and western Guangdong during 2018 and 2019, and were analyzed for 16 mycotoxins by multiple reaction monitoring mode of ultra performance liquid chromatography-tandem mass spectrometer. Results Among the 120 paddy rice samples, 19.17% (23/120) were positive for mycotoxins, and the main polluants were aflatoxins and fumonisins. FB1 were detected in 9.17% (11/120) of the samples, followed by 8.33% (10/120) for AFB1. Two samples had the AFB1 concentrations above the tolerance limit of 10 μg/kg. The detection values were 73.90 and 18.80 μg/kg, respectively. Among 6 trichothecene mycotoxins, only deoxynivalenol (1.67%, 2/120) and its acetyl derivatives[0.83% (1/120) for 3-Ac-DON and 0.83% (1/120) for 15-Ac-DON] were found. ZEN was found in 3.33% (4/120) of the samples. Additionally, 1.67% (2/120) of the paddy rice samples were positive for sterigmatocystin. The ochratoxin A, nivalenol, T-2 and HT-2 mycotoxins were not found in the paddy rice samples. The co-occurrence of two or more mycotoxins was confirmed in 8.33% (10/120) of the paddy rice samples, mainly combination was AFB1 and other mycotoxins. The contamination patterns were different in the eight cities. The paddy rice samples from Zhanjiang was mainly contaminated by FB1, FB2, DON and 3-Ac-DON. Samples from Heyuan were mainly contaminated by AFB1, AFB2, sterigmatocystin, FB1 and FB2. The concentration levels of ZEN, DON and 3-Ac-DON were relatively higher in samples from Shaoguan. Conclusion The paddy rice samples from Guangdong Province were contaminated by multiple mycotoxins, and the pollution patterns were different in different areas. In terms of the co-occurence of mycotoxins, some measures should be conducted to assess the exposure risk, reduce the damage, and protect the consumers food safety

High-pressure x-ray diffraction study of SrMoO4 and pressure-induced structural changes

SrMoO4 was studied under compression up to 25 GPa by angle-dispersive x-ray diffraction. A phase transition was observed from the scheelite-structured ambient phase to a monoclinic fergusonite phase at 12.2(9) GPa with cell parameters a = 5.265(9) A, b = 11.191(9) A, c = 5.195 (5) A, and beta = 90.9, Z = 4 at 13.1 GPa. There is no significant volume collapse at the phase transition. No additional phase transitions were observed and on release of pressure the initial phase is recovered, implying that the observed structural modifications are reversible. The reported transition appeared to be a ferroelastic second-order transformation producing a structure that is a monoclinic distortion of the low-pressure phase and was previously observed in compounds isostructural to SrMoO4. A possible mechanism for the transition is proposed and its character is discussed in terms of the present data and the Landau theory. Finally, the EOS is reported and the anisotropic compressibility of the studied crystal is discussed in terms of the compression of the Sr-O and Mo-O bonds.Comment: 36 pages, 9 figures, 1 tabl

A Built-In Strategy for Containment of Transgenic Plants: Creation of Selectively Terminable Transgenic Rice

Plant transgenic technology has been widely utilized for engineering crops for trait improvements and for production of high value proteins such as pharmaceuticals. However, the unintended spreading of commercial transgenic crops by pollination and seed dispersal is a major concern for environmental and food safety. Simple and reliable containment strategies for transgenes are highly desirable. Here we report a novel method for creating selectively terminable transgenic rice. In this method, the gene(s) of interest is tagged with a RNA interference cassette, which specifically suppresses the expression of the bentazon detoxification enzyme CYP81A6 and thus renders transgenic rice to be sensitive to bentazon, a herbicide used for rice weed control. We generated transgenic rice plants by this method using a new glyphosate resistant 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene from Pesudomonas putida as the gene of interest, and demonstrated that these transgenic rice plants were highly sensitive to bentazon but tolerant to glyphosate, which is exactly the opposite of conventional rice. Field trial of these transgenic rice plants further confirmed that they can be selectively killed at 100% by one spray of bentazon at a regular dose used for conventional rice weed control. Furthermore, we found that the terminable transgenic rice created in this study shows no difference in growth, development and yield compared to its non-transgenic control. Therefore, this method of creating transgenic rice constitutes a novel strategy of transgene containment, which appears simple, reliable and inexpensive for implementation

How does the environmental attention of local governments affect regional green development? Empirical evidence from local governments in China

Abstract Due to the continuous progress of constructing sustainable environments in China, the role played by the Chinese central government as the main body for promoting green development is worth studying. Because China’s ecological civilization building has been steadily progressing. Governments at all levels in China have prioritised the development of environmental civilization as a key aspect of regional growth. However, the actual impact and mechanisms of influence of this construction still require further investigation. This paper constructs a government environmental attention index using word frequency found in the Report on the Work of the Government. It uses a long difference model to study the impact and mechanism of government environmental attention on urban green efficiency, carbon emissions and air quality. The results show that the government’s ecological attention can improve green efficiency, and air quality, but it can also lead to increased carbon emissions, and the impact is particularly evident in the eastern and western regions of the country. This is because the government’s emphasis on the environment significantly impacts on environmental regulations and technological progress, and is directly influenced by fiscal bias and financial pressure. Given the results, we put forward some policy suggestions that local governments should improve the intensity of local environmental regulation, encourage green technology innovation, provide encouraging conditions for environmental development, and establish a long-term strategic vision. The findings in this study has implications for promoting the implementation of local governments’ environmental protection and the development of sustainable societies in China