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We propose and investigate a fiber-optic sensor of As2Se3 chalcogenide (ChG) microfiber laterally adhered on the hollow-core fiber (HCF) end face. HCF is fused with a single-mode fiber to form Fabry–Perot interferometer (FPI) between single-mode fiber (SMF) end face and ChG microfiber. ChG microfiber is ultra-sensitive to the small perturbations in the surroundings, because of its high refractive index and small Young's modulus. Furthermore, relative to traditional fiber-optic FPI comprised by thin film, our proposed FPI with thin-diameter ChG microfiber could respond to mechanical vibrations over a broad range of frequencies. Based on finite-element simulation, ChG microfiber has ultra-broadband dynamic frequency response, up to several hundreds of megahertz accompanied by a very small response strength decay, in comparison to the frequency response of ChG film which is typically less than 30 MHz. ChG microfiber-based FPI is also used in the static refractometric sensing with sensitivity of 1563 nm/RIU. Such a novel fiber-optic sensor offers excellent potential for the nondestructive detection and advanced biomedical sensing. [ABSTRACT FROM AUTHOR]

[Objectives]In terms of ocean sensors,their energy consumption points are scattered and the load fluctuation is drastic,with urgent need in energy conservation and consumption reduction. In order to optimize the energy supply of the ocean sensors,this paper studies the Ship-borne Energy Network(SEN) for ocean sensors.[Methods]Firstly,the feasibility of SEN model is analyzed based on the development of vehicle energy network,dynamic wireless charging technology and electric ship technology. Next,based on the characteristics of the ocean sensor,the SEN model is established to propose two issues of energy transmission maximization and energy loss minimization and define problem model and constraint function. Finally,we select the basic experimental data set through the open source model MaritimeSim.[Results] The experimental results show that SEN can transfer offshore renewable energy to ocean sensors node under some reasonable settings,complement the power network and enhance its power transmission capability.[Conclusions] The study results can provide new design method for optimizing the energy supply of ocean sensors.

Abstract Background Biological nitrogen fixation is highly controlled at the transcriptional level by regulatory networks that respond to the availability of fixed nitrogen. In many diazotrophs, addition of excess ammonium in the growth medium results in immediate repression of nif gene transcription. Although the regulatory cascades that control the transcription of the nif genes in proteobacteria have been well investigated, there are limited data on the kinetics of ammonium-dependent repression of nitrogen fixation. Results Here we report a global transcriptional profiling analysis of nitrogen fixation and ammonium repression in Pseudomonas stutzeri A1501, a root-associated and nitrogen-fixing bacterium. A total of 166 genes, including those coding for the global nitrogen regulation (Ntr) and Nif-specific regulatory proteins, were upregulated under nitrogen fixation conditions but rapidly downregulated as early as 10 min after ammonium shock. Among these nitrogen fixation-inducible genes, 95 have orthologs in each of Azoarcus sp. BH72 and Azotobacter vinelandii AvoP. In particular, a 49-kb expression island containing nif and other associated genes was markedly downregulated by ammonium shock. Further functional characterization of pnfA, a new NifA-σ54-dependent gene chromosomally linked to nifHDK, is reported. This gene encodes a protein product with an amino acid sequence similar to that of five hypothetical proteins found only in diazotrophic strains. No noticeable differences in the transcription of nifHDK were detected between the wild type strain and pnfA mutant. However, the mutant strain exhibited a significant decrease in nitrogenase activity under microaerobic conditions and lost its ability to use nitrate as a terminal electron acceptor for the support of nitrogen fixation under anaerobic conditions. Conclusions Based on our results, we conclude that transcriptional regulation of nif gene expression in A1501 is mediated by the nif-specific and ntr gene regulatory systems. Furthermore, microarray and mutational analyses revealed that many genes of unknown function may play some essential roles in controlling the expression or activity of nitrogenase. The findings presented here establish the foundation for further studies on the physiological function of nitrogen fixation-inducible genes.