2,484 research outputs found

    Graphene-Based FET Detector for E. coli K12 Real-Time Monitoring and Its Theoretical Analysis

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    This paper presents a theoretical analysis for a graphene-based FET real-time detector of the target bacteria E. coli K12. The motivation for this study is to design a sensor device for detection of bacteria in food and water in order to guarantee food safety. Graphene is chosen as our material for sensor design, which has outstanding electrical, physical, and optical performance. In our sensor structure, graphene-based solution gate field effect transistor (FET) is the device model; fabrication and functionalization protocol are presented together in this paper. What is more, a real-time signal display system is the accompanied equipment for our designed biosensor device. In this system, the sensor bias current signal would change obviously when the target bacteria are attached to the sensor surface. And the bias current increases when the E. coli concentration increases. In the latter part, a theoretical interpretation of the sensor signal is to explain the bias current increasing after the E. coli K12 attachment.published_or_final_versio

    Twisted bilayer U(1) Dirac spin liquids

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    When two layers of two-dimensional materials are assembled with a relative twist, moir\'e patterns arise, inducing a tremendous wealth of exotic phenomena. In this work, we consider twisting two triangular lattices hosting Dirac quantum spin liquids. Using recent results for the monopole scaling dimensions and quantum numbers of the Dirac spin liquid state, we show that, in the bilayer system, interlayer monopole tunneling is a symmetry-allowed relevant perturbation and can lead to ordered bilayer states. We analyze the effect of this interlayer tunneling using a mean field theory in both the weak-coupling and strong-coupling regimes. In particular, when the spin monopoles can tunnel, we find a tunable lattice of magnetic vortices at strong coupling.Comment: 22 pages, 5 figure

    Revealing the role of λ-carrageenan on the enhancement of gel-related properties of acid-induced soy protein isolate/λ-carrageenan system

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    This work explored the pivotal role of λ-carrageenan in fortifying the gel structure, consequently enhancing gel-related attributes within an acid-induced soy protein isolate/λ-carrageenan system (SPI/Car). The model system was prepared by subjecting a thermally treated mixture of these two biopolymers to acidification. Small-angle X-ray scattering (SAXS) and chemical force analysis unveiled the profound influence of hydrogen bonding and electrostatic interactions in the formation of the intricate network architecture of SPI/Car gels. Remarkably, λ-carrageenan interacted with the hydrophilic groups on the surface of agglomerated SPI particles, effectively composing the fundamental framework of SPI/Car gels. Simultaneously, λ-carrageenan emerged as a linchpin through hydrogen bonding, establishing pivotal crosslinking connections. The introduction of λ-carrageenan resulted in a reduction in SPI particle size, the dispersion of previously formed aggregates, and a subtle blurring of the SPI particles. It also significantly heightened the prevalence of hydrogen bonding and electrostatic interactions, ultimately giving rise to a robust yet somewhat coarse gel structure, as evidenced by confocal laser scanning microscopy (CLSM). These profound structural alterations underpinned the enhancement of water-holding capacity (WHC) and gel hardness in SPI/Car gels. These findings hold promise for the rational design and application of SPI-based systems in the production of processed vegetarian and vegan foods

    Enhanced Orbital Degeneracy in Momentum Space for LaOFeAs

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    The Fermi surfaces (FS) of LaOFeAs (in kzk_z=0 plane) consist of two hole-type circles around Γ\Gamma point, which do not touch each other, and two electron-type co-centered ellipses around M point, which are degenerate along the M-X line. By first-principles calculations, here we show that additional degeneracy exists for the two electron-type FS, and the crucial role of F-doping and pressure is to enhance this orbital degeneracy. It is suggested that the inter-orbital fluctuation is the key point to understand the unconventional superconductivity in these materials.Comment: 4 pages, 5 figure

    Qinghai–tibetan plateau peatland sustainable utilization under anthropogenic disturbances and climate change

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    Often referred to as the “Third Pole,” China's Qinghai–Tibetan Plateau developed large amounts of peatland owing to its unique alpine environment. As a renewable resource, peat helps to regulate the climate as well as performing other important functions. However, in recent years, intensifying climate change and anthropogenic disturbances have resulted in peatland degradation and consequently made sustainable development of peatland more difficult. This review summarizes peatland ecological and economic functions, including carbon sequestration, biodiversity conservation, energy supplies, and ecotourism. It identifies climate change and anthropogenic disturbances as the two key factors attributing to peatland degradation and ecosystem carbon loss. Current problems in environmental degradation and future challenges in peatland management under the effects of global warming are also discussed and highlighted

    Anomalies of upper critical field in the spinel superconductor LiTi2_2O4δ_{4-\delta}

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    High-field electrical transport and point-contact tunneling spectroscopy were used to investigate superconducting properties of the unique spinel oxide, LiTi2_2O4δ_{4-\delta} films with various oxygen content. We find that the upper critical field Bc2B_\mathrm{c2} gradually increases as more oxygen impurities are brought into the samples by carefully tuning the deposition atmosphere. It is striking that although the superconducting transition temperature and energy gap are almost unchanged, an astonishing isotropic Bc2B_\mathrm{c2} up to \sim 26 Tesla is observed in oxygen-rich sample, which is doubled compared to the anoxic sample and breaks the Pauli limit. Such anomalies of Bc2B_\mathrm{c2} were rarely reported in other three dimensional superconductors. Combined with all the anomalies, three dimensional spin-orbit interaction induced by tiny oxygen impurities is naturally proposed to account for the remarkable enhancement of Bc2B_\mathrm{c2} in oxygen-rich LiTi2_2O4δ_{4-\delta} films. Such mechanism could be general and therefore provides ideas for optimizing practical superconductors with higher Bc2B_\mathrm{c2}
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