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Wang J.,National University of Defense Technology | Du X.,National University of Defense Technology | Du X.,Beijing Institute of Pharmacology and Toxicology | Pan W.,National University of Defense Technology | And 3 more authors.
Journal of Photochemistry and Photobiology C: Photochemistry Reviews | Year: 2015

The cryptochrome/photolyase superfamily is a class of flavoproteins that can regulate the growth and development in plants, as well as the circadian clock and the potential magnetic navigation in animals, primarily by absorbing UV-A and blue light. It is generally agreed that these functions depend on the photochemical reaction of the flavin adenine dinucleotide (FAD) chromophore, non-covalently binding to cryptochromes or photolyases. Irradiation can initiate either photoreduction between FAD and certain electron donors or electron jumping in FAD, thereby leading to the generation of intermediates that activate the protein. This signaling process is known as photoactivation. Subsequently, the activated protein will interact with downstream receptors to transfer the photo and magnetic signals. Based on in-depth research on photoactivation, two photo-cycle mechanisms for the photoreception/photosignaling of the cryptochrome/photolyase superfamily, i.e., the photolyase model and the phototropin model, have been proposed. There is no apparent alternative to the photo-cycle of cyclobutane pyrimidine dimer (CPD) or (6-4) photolyase following the photolyase model. However, the mechanism is not clear for the photoactivation of cryptochromes and CRY-DASH, a new subcategory of photolyase. Since the photoactivation process is the first step for the physiological function of proteins, more and improved research efforts in this field have been widely developed. This review first briefly presents the structure, the photoactivation, and the repair mechanism of CPD and (6-4) photolyase. Next, we review in detail the photoactivation of cryptochromes and CRY-DASH by analyzing the current status of research, as well as the contradictions in the resting redox states of FAD, intermediates in photoreactions, the photo-cycle of FAD, the signaling state of proteins, and the necessity of given tryptophans for protein activity. Based on these studies, the correlations of photoactivation and photo-cycle mechanisms, as well as the correlations of photoactivation and magnetoreception of proteins, are discussed. Finally the crucial open questions regarding the photoactivation mechanisms of the cryptochrome/photolyase superfamily are outlined, considering the hypothesis for a cryptochrome-based model of avian magnetoreception. © 2014 Elsevier B.V.

Wang H.,Beijing Research Institute of Chemical Defense | Wang H.,State Key Laboratory of NBC Protection for Civilian
Frontiers of Environmental Science and Engineering | Year: 2013

The outdoor smog chamber was used to thorough investigate the rate constants of gas-phase reaction between dimethyl sulfide (DMS) and ozone (O3) under conditions of relative humidity 55.0%-67.8% at (296±2)K for the first time. The rate constants were measured, at a total pressure of 1 atm, to be (10.4±0.2) ± 10-19 cm3·molecule-1·s-1 at relative humidity of 67.5%± 0.3% at 298K, (10.1±0.1) ± 10-19 cm3·molecule-1·s-1 at relative humidity of 66.5%±0.5% at 296K, (7.75±0.39) ± 10-19 cm3·molecule-1·s-1at relative humidity of 64.8%± 0.1% at 294K and (3.42±0.21) ± 10-19 cm3·molecule-1·s-1at relative humidity of 55.8%±0.8% at 295K. Base on these results, it is possible to see the reaction of O3/DMS in the presence of water vapor as an important sink for DMS in the earth atmosphere. © 2013 Higher Education Press and Springer-Verlag Berlin Heidelberg.

Li J.-Y.,CAS Institute of Electronics | Lu D.-F.,CAS Institute of Electronics | Qi Z.-M.,CAS Institute of Electronics | Qi Z.-M.,State Key Laboratory of NBC Protection for Civilian
Wuli Xuebao/Acta Physica Sinica | Year: 2015

Miniature Fourier transform spectrometer (FTS) has attracted considerable interest because of its important application in spaceborne spectroscopy and as a portable analytical tool for rapid on-site chemical/biochemical detection. In a previous paper, a stationary miniature FTS constructed with an electro-optic (EO) modulator of a LiNbO3 (LN) waveguide Mach-Zehnder interferometer (MZI) containing push-pull electrodes was demonstrated. This stationary miniature FTS is operated in the near-infrared region with either nonlinear or linear scanning of the modulating voltage. The simple and mirrorless structure renders the device compact, vibration resistant, and cost-effective. However, the spectral resolution of the proposed prototype FTS was not satisfactory due to the limited optical pathlength difference (OPD), thereby limiting the device application. To improve its spectral resolution, the factors affecting the spectral resolution of the LN waveguide-based FTS is investigated in this paper. Findings show that the spectral resolution is inversely proportional to the maximum OPD, which is proportional to the length of the EO modulating region. A simple method for two-fold enhancement of the spectral resolution of the FTS is proposed based on the end-face reflection in LN waveguide interferometer. With the end-face reflection geometry the guided mode can propagate back and forth in the LN waveguide, making the mode passing through the EO modulating region twice and consequently leading to two times enhancement of the OPD. Therefore, the end-face reflection geometry enables to double the maximum OPD of the interferometer without increasing the device size and thus to offer the device a two-fold enhanced spectral resolution according to the equation for FTS resolution. Two prototypes of FTS with and without the end-face reflection structure are prepared using the same commercial LN waveguide EO modulator. The spectral resolutions in terms of the full-width at half maximum (FWHM) at different wavelengths for the two prototypes of FTS are measured using a series of distributed feedback lasers. The FWHM measured at a specific wavelength with the end-face reflection structure is half as large as that obtained without the end-face reflection structure. Experimental results are in excellent agreement with the theoretical data, demonstrating the applicability of the end-face reflection method to the spectral resolution enhancement. ©, 2015, Chinese Physical Society. All right reserved.

Li Z.-J.,CAS Institute of High Energy Physics | Wang L.,CAS Institute of High Energy Physics | Yuan L.-Y.,CAS Institute of High Energy Physics | Xiao C.-L.,Soochow University of China | And 8 more authors.
Journal of Hazardous Materials | Year: 2015

Zero-valent iron nanoparticle (ZVI-np) and its graphene composites were prepared and applied in the removal of uranium under anoxic conditions. It was found that solutions containing 24ppm U(VI) could be completely cleaned up by ZVI-nps, regardless of the presence of NaHCO3, humic acid, mimic groundwater constituents or the change of solution pH from 5 to 9, manifesting the promising potential of this reactive material in permeable reactive barrier (PRB) to remediate uranium-contaminated groundwater. In the measurement of maximum sorption capacity, removal efficiency of uranium kept at 100% until C0(U)=643ppm, and the saturation sorption of 8173mgU/g ZVI-nps was achieved at C0(U)=714ppm. In addition, reaction mechanisms were clarified based on the results of SEM, XRD, XANES, and chemical leaching in (NH4)2CO3 solution. Partially reductive precipitation of U(VI) as U3O7 was prevalent when sufficient iron was available; nevertheless, hydrolysis precipitation of U(VI) on surface would be predominant as iron got insufficient, characterized by releases of Fe2+ ions. The dissolution of Fe0 cores was assigned to be the driving force of continuous formation of U(VI) (hydr)oxide. The incorporation of graphene supporting matrix was found to facilitate faster removal rate and higher U(VI) reduction ratio, thus benefitting the long-term immobilization of uranium in geochemical environment. © 2015 Elsevier B.V.

Yu T.,CAS Institute of Chemistry | Yu T.,State Key Laboratory of NBC Protection for Civilian | Ying T.-Y.,CAS Institute of Chemistry | Ying T.-Y.,State Key Laboratory of NBC Protection for Civilian | And 6 more authors.
RSC Advances | Year: 2014

A facile and highly sensitive signaling strategy for organophosphorus compounds (OPs) based on acetylcholinesterase (AChE)-acetylthiocholine (ATCh) catalytic reaction and II-VI group photoluminescent CdTe quantum dots (QDs) prepared from low molar ratio of thiols to Cd2+ has been developed. Photoluminescence (PL) of the ensemble system can be modulated by the enzyme catalytic reaction and OPs, as the resulting catalytic product, namely thiolcholine (TCh) and H+, can significantly decrease PL of the prepared QDs, while OPs can inhibit this AChE-ATCh catalytic reaction. This signaling platform shows much more enhanced sensitivity to highly toxic OPs such as nerve agents and organophosphate pesticides, compared with previous reports. © 2014 The Royal Society of Chemistry.

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