Fast Polarization Switching Demonstration Using Crossed-Planar Undulator in a Seeded Free Electron Laser

Fast polarization switching of light sources is required over a wide spectral range to investigate the symmetry of matter. In this Letter, we report the first experimental demonstration of the crossed-planar undulator technique at a seeded free-electron laser, which holds great promise for the full control and fast switching of the polarization of short-wavelength radiation. In the experiment, the polarization state of the coherent radiation at the 2nd harmonic of the seed laser is switched successfully. The experiment results confirm the theory, and pave the way for applying the crossed-planar undulator technique for the seeded X-ray free electron lasers.Comment: 5 pages, 5 figure

Monoclonal Antibodies against Accumulation-Associated Protein Affect EPS Biosynthesis and Enhance Bacterial Accumulation of Staphylococcus epidermidis

Because there is no effective antibiotic to eradicate Staphylococcus epidermidis biofilm infections that lead to the failure of medical device implantations, the development of anti-biofilm vaccines is necessary. Biofilm formation by S. epidermidis requires accumulation-associated protein (Aap) that contains sequence repeats known as G5 domains, which are responsible for the Zn2+-dependent dimerization of Aap to mediate intercellular adhesion. Antibodies against Aap have been reported to inhibit biofilm accumulation. In the present study, three monoclonal antibodies (MAbs) against the Aap C-terminal single B-repeat construct followed by the 79-aa half repeat (AapBrpt1.5) were generated. MAb18B6 inhibited biofilm formation by S. epidermidis RP62A to 60% of the maximum, while MAb25C11 and MAb20B9 enhanced biofilm accumulation. All three MAbs aggregated the planktonic bacteria to form visible cell clusters. Epitope mapping revealed that the epitope of MAb18B6, which recognizes an identical area within AapBrpt constructs from S. epidermidis RP62A, was not shared by MAb25C11 and MAb20B9. Furthermore, all three MAbs were found to affect both Aap expression and extracellular polymeric substance (EPS, including extracellular DNA and PIA) biosynthesis in S. epidermidis and enhance the cell accumulation. These findings contribute to a better understanding of staphylococcal biofilm formation and will help to develop epitope-peptide vaccines against staphylococcal infections

Bifunctional zirconium Schiff base complexes as adhesive, precursor of zirconium-containing polymers, and initiator for lactone polymerizations

By taking advantage of the unequal activity of the two NCO groups of toluene-2,4-diisocyanate at room temperature, a pure zirconium coordination compound with two reactive NCO functionalities is obtained, which can function as a precursor for polymerizations with organic primary amines and primary alcohols. A copolymer with poly(tetrahydrofuran) has been formed in this manner. A copolymer of Zr(sal)\sb4 (sal\sp- = salicylaldehydato) and 3,3\sp\prime-diaminobenzidine, (Zr(tsdb)) \sb{\rm n}, which theoretically has one Zr(sal)\sb2 end-group and one diamine end-group in an average polymer chain, can strongly adhere to silica and alumina surfaces. To understand the hydrolytic behavior of the Zr(sal)\sb2 end-groups in the (Zr(tsdb)) \sb{\rm n} polymer, the hydrolysis of Zr(sal)\sb4 has been studied by electronic, vibrational, and proton magnetic resonance spectroscopies. The results show that Zr(sal)\sb4 is almost insensitive to moisture in the solid state, but can be hydrolyzed quickly in solution. The adhesion of the (Zr(tsdb)) \sb{\rm n} oligomer on silica or alumina has been further studied by x-ray photoelectron spectroscopy (XPS), including the use of Zr(sal)\sb4 as a model modifier. The XPS data show that both Zr(sal)\sb4 and (Zr(tsdb)) \sb{\rm n} can strongly adhere to silica and/or alumina surfaces, and the adhesion of (Zr(tsdb)) \sb{\rm n} is probably via both the Zr(sal)\sb2 and the diamine end-groups by forming the Zr-O-Si(Al) linkages and the (-NH\sb2)(SiOH) H-bonds, and the latter may be broken under ultrasonication. Moreover, because (Zr(tsdb)) \sb{\rm n} can initiate the polymerization of $\beta$-($\pm)$-butyrolactone ($\beta$-BL), a detailed study of the (Zr(tsdb)) \sb{\rm n} initiated polymerization of $\beta$-BL has been conducted to clarify the polymerization mechanism. In addition, the polymerization of $\varepsilon$-caprolactone ($\varepsilon$-CL) has been also studied in the presence of (Zr(tsdb)) \sb{\rm n}. Model initiators, Zr(sal)\sb4 and o-diaminobenzene were used as well for comparison. The results from spectral and chromatographic investigations enable us to propose a dual-site ring-fission mechanism for the (Zr(tsdb)) \sb{\rm n}-initiated $\beta$-BL polymerization and a coordination-insertion mechanism for the Zr(sal)\sb4-initiated $\varepsilon$-CL polymerization

Impact of Green Finance and Environmental Regulations on the Green Innovation Efficiency in China

Innovation is the first driving force for development, and green innovation efficiency (GIE) plays a very important role in regional sustainable development. Data from 31 provinces and cities in China from 2011 to 2020 were used to select the proportion of energy saving and environmental protection costs in GDP as the green financial value, and the proportion of industrial pollution control input in GDP as the environmental regulation index. Green innovation efficiency is measured from two aspects of input and output by DEA method, and carried out for 31 provinces and cities in three regions. Using the DEA-Malmquist index to measure regional green innovation efficiency, the results show that the green innovation efficiency in three regions basically presents an upward trend, but the upward trend of green innovation efficiency is different between the three regions. A Tobit regression model is constructed to explore the impact of green finance and environmental regulations on the green innovation efficiency in these three regions. Research indicates that environmental regulations, the proportion of output value of tertiary industry in GDP, industrial structure, and foreign direct investment have significant impacts on the green innovation efficiency in all regions. Green finance, industrial structure, and power consumption have a significant impact on the green innovation efficiency in eastern China. Industrial structure has a significant impact on green innovation efficiency in central China, while power consumption and industrial structure have a significant impact on green innovation efficiency in western China. Therefore, each region needs to improve the standard of environmental regulation innovation, and introduce and use foreign investment in a scientific and reasonable way so as to promote the improvement of industrial infrastructure

Impact of Green Finance and Environmental Regulations on the Green Innovation Efficiency in China

Innovation is the first driving force for development, and green innovation efficiency (GIE) plays a very important role in regional sustainable development. Data from 31 provinces and cities in China from 2011 to 2020 were used to select the proportion of energy saving and environmental protection costs in GDP as the green financial value, and the proportion of industrial pollution control input in GDP as the environmental regulation index. Green innovation efficiency is measured from two aspects of input and output by DEA method, and carried out for 31 provinces and cities in three regions. Using the DEA-Malmquist index to measure regional green innovation efficiency, the results show that the green innovation efficiency in three regions basically presents an upward trend, but the upward trend of green innovation efficiency is different between the three regions. A Tobit regression model is constructed to explore the impact of green finance and environmental regulations on the green innovation efficiency in these three regions. Research indicates that environmental regulations, the proportion of output value of tertiary industry in GDP, industrial structure, and foreign direct investment have significant impacts on the green innovation efficiency in all regions. Green finance, industrial structure, and power consumption have a significant impact on the green innovation efficiency in eastern China. Industrial structure has a significant impact on green innovation efficiency in central China, while power consumption and industrial structure have a significant impact on green innovation efficiency in western China. Therefore, each region needs to improve the standard of environmental regulation innovation, and introduce and use foreign investment in a scientific and reasonable way so as to promote the improvement of industrial infrastructure

Selective oxidation of styrene catalyzed by cerium-doped cobalt ferrite nanocrystals with greatly enhanced catalytic performance

Abstract The rare earth metal Ce-doped cobalt ferrite samples CexCo1−xFe2O4 (x=0.1, 0.3, 0.5) were prepared by the sol–gel autocombustion route. The as-prepared samples were characterized by X-ray diffractometry, scanning electron microscopy, transmission electron microscopy, ICP–atomic emission spectroscopy, and N2 physisorption. Their catalytic performance was evaluated in oxidation of styrene using hydrogen peroxide (30%) as oxidant. Compared with pristine CoFe2O4, the Ce-doped samples were found to be more efficient catalysts for the oxidation of styrene to benzaldehyde, with greatly enhanced catalytic performance. Especially, when Ce0.3Co0.7Fe2O4 was used as catalyst, 90.3% styrene conversion and 91.5% selectivity for benzaldehyde were obtained at 90°C for 9h reaction. The catalyst can be magnetically separated easily for reuse, and no obvious loss of activity was observed when it was reused in five consecutive runs