1,867 research outputs found
Conserved quantities for asymptotically AdS spacetimes in quadratic curvature gravity in terms of a rank-4 tensor
We investigate the conserved quantities associated to Killing isometries for
asymptotically AdS spacetimes within the framework of quadratic-curvature
gravity. By constructing a rank-4 tensor possessing the same index symmetries
as the ones of the Riemann tensor, we propose a 2-form potential resembling the
Noether one for quadratic-curvature gravity. Such a potential is compared with
the results via other methods existing in the literature to establish the
equivalence. Then this potential is adopted to define conserved quantities of
asymptotically AdS spacetimes. As applications, we explicitly compute the mass
of static spherically-symmetric spacetimes, as well as the mass and the angular
momentum for rotating spacetimes, such as the four(higher)-dimensional Kerr-AdS
black holes and black strings embedded in quadratic-curvature gravities.
Particularly, we emphasize the conserved charges of Einstein-Gauss-Bonnet, Weyl
and critical gravities, together with the ones for the asymptotically AdS
solutions satisfying vacuum Einstein field equations.Comment: 50 pages, no figures, accepted by PR
Lable-free aptamer portable colorimetric smartphone for gliadin detection in food
For individuals with celiac disease (CD), the current clinical therapy option available is a lifelong gluten-free diet. Therefore, it is essential to swiftly and efficiently detect gluten in foods. A colorimetric sensor has been developed, which operates by regulating the aggregation and dispersion state of AuNPs induced by high concentration NaCl through the specific binding of gliadin and aptamer, thereby achieving rapid detection of gliadin in flour. It is found that the sensor exhibits good linearity in the concentration range of 0.67–10 μM and the LOD (3σ/S) is 12 nM. And it can accurately distinguish various types of free-gliadin samples, with a spiked recovery rate of 85%–122.3%. To make the detection process more convenient, the colorimetric results of the biosensor were translated into RGB color-gamut parameters by a smartphone color-picking program for further analysis. Gliadin can still be accurately quantified with the established smartphone platform, and a correlation coefficient of 0.988 was found. The proposed portable smartphone aptamer colorimetric sensing device has achieved satisfactory results in the rapid detection of gliadin in food
Layer-dependent transport properties in the Moir\'e of strained homobilayer transition metal dichalcogenides
Bilayer moir\'e structures have attracted significant attention recently due
to their spatially modulated layer degrees of freedom. However, the
layer-dependent transport mechanism in the moir\'e structures is still a
problem to be explored. Here we investigate the layer-dependent transport
properties regulated by the strain, the interlayer bias and the number of
moir\'e periods in a strained moir\'e homobilayer TMDs nanoribbon based on
low-energy efficient models. The charge carriers can pass perfectly through the
scattering region with the moir\'e potential. While, it is noted that the
overall transmission coefficient is mainly contributed from either intralayer
or interlayer transmissions. The transition of transport mechanism between
intralayer and interlayer transmissions can be achieved by adjusting the
strain. The intralayer transmissions are suppressed and one of the interlayer
transmissions can be selected by a vertical external electric field, which can
cause a controllable layer polarization. Moreover, the staggered intralayer and
interlayer minigaps are formed as the number of moir\'e periods increases in
the scattering region due to the overlap of the wave functions in two adjacent
moir\'e periods. Our finding points to an opportunity to realize layer
functionalities by the strain and electric field.Comment: 6 pages, 4 figure
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