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A bstract We study 3d quantum gravity with two asymptotically anti-de Sitter regions, in particular, using its relation with coupled Alekseev-Shatashvili theories and Liouville theory. Expressions for the Hartle-Hawking state, thermal 2 n -point functions, torus wormhole correlators and Wheeler-DeWitt wavefunctions in different bases are obtained using the ZZ boundary states in Liouville theory. Exact results in 2d Jackiw-Teitelboim (JT) gravity are uplifted to 3d gravity, with two copies of Liouville theory in 3d gravity playing a similar role as Schwarzian theory in JT gravity. The connection between 3d gravity and the Liouville ZZ boundary states are manifested by viewing BTZ black holes as Maldacena-Maoz wormholes, with the two wormhole boundaries glued along the ZZ boundaries. In this work, we also study the factorization problem of the Hartle-Hawking state in 3d gravity. With the relevant defect operator that imposes the necessary topological constraint for contractibility, the trace formula in gravity is modified in computing the entanglement entropy. This trace matches with the one from von Neumann algebra considerations, further reproducing the Bekenstein-Hawking area formula from entanglement entropy. Lastly, we propose a calculation for off-shell geometrical quantities that are responsible for the ramp behavior in the late time two-point functions, which follows from the understanding of the Liouville FZZT boundary states in the context of 3d gravity, and the identification between Verlinde loop operators in Liouville theory and “baby universe” operators in 3d gravity.

A bstract We consider the problem of defining a microcanonical thermofield double state at fixed energy and angular momentum from the gravitational path integral. A semiclassical approximation to this state is obtained by imposing a mixed boundary condition on an initial time surface. We analyze the corresponding boundary value problem and gravitational action. The overlap of this state with the canonical thermofield double state, which is interpreted as the Hartle-Hawking wavefunction of an eternal black hole in a mini-superspace approximation, is calculated semiclassically. The relevant saddlepoint is a higher-dimensional, rotating generalization of the wedge geometry that has been studied in two-dimensional gravity. Along the way we discuss a new corner term in the gravitational action that arises at a rotating horizon.

As a cost-effective and environmentally benign photocatalyst, hydrothermal carbonation carbon (HTCC) has been extensively studied in the fields of resource utilization and environmental remediation. In this study, HTCC photocatalysts with efficient photocatalytic performances were prepared from straw using acid modification under hydrothermal conditions. The as-prepared HTCC photocatalysts were applied to the degradation of microcystin-LR and the reduction of aqueous Cr(VI). The critical role of acid modification in the photocatalytic performances of the HTCC photocatalysts was systematically investigated. The results demonstrated that acid-modified photocatalysts exhibited a significantly enhanced removal efficiency for Cr(VI) and microcystin-LR under visible light irradiation. A series of characterization techniques, including Raman spectroscopy and N2 adsorption–desorption analysis, revealed that the superior photocatalytic activities of acid-modified HTCC could be attributed to its higher aromatization level, enhanced light-harvesting ability, and increased concentration of active sites compared with pristine HTCC. Furthermore, electron spin resonance (ESR) and trapping experiments indicated that hydrogen radicals (·H) served as the primary active species in the photocatalytic Cr(VI) reduction of straw-based HTCC. This work provides both practical and theoretical insights into the resource utilization of agricultural waste and the remediation of environmental pollution.

We perform a numerical study of the heat transfer and flow structure of Rayleigh–Bénard (RB) convection in (in most cases regular) porous media, which are comprised of circular, solid obstacles located on a square lattice. This study is focused on the role of porosity$\\unicode[STIX]{x1D719}$in the flow properties during the transition process from the traditional RB convection with$\\unicode[STIX]{x1D719}=1$(so no obstacles included) to Darcy-type porous-media convection with$\\unicode[STIX]{x1D719}$approaching 0. Simulations are carried out in a cell with unity aspect ratio, for Rayleigh number$Ra$from$10^{5}$to$10^{10}$and varying porosities$\\unicode[STIX]{x1D719}$, at a fixed Prandtl number$Pr=4.3$, and we restrict ourselves to the two-dimensional case. For fixed$Ra$, the Nusselt number$Nu$is found to vary non-monotonically as a function of$\\unicode[STIX]{x1D719}$; namely, with decreasing$\\unicode[STIX]{x1D719}$, it first increases, before it decreases for$\\unicode[STIX]{x1D719}$approaching 0. The non-monotonic behaviour of$Nu(\\unicode[STIX]{x1D719})$originates from two competing effects of the porous structure on the heat transfer. On the one hand, the flow coherence is enhanced in the porous media, which is beneficial for the heat transfer. On the other hand, the convection is slowed down by the enhanced resistance due to the porous structure, leading to heat transfer reduction. For fixed $\\unicode[STIX]{x1D719}$, depending on$Ra$, two different heat transfer regimes are identified, with different effective power-law behaviours of$Nu$versus$Ra$, namely a steep one for low$Ra$when viscosity dominates, and the standard classical one for large$Ra$. The scaling crossover occurs when the thermal boundary layer thickness and the pore scale are comparable. The influences of the porous structure on the temperature and velocity fluctuations, convective heat flux and energy dissipation rates are analysed, further demonstrating the competing effects of the porous structure to enhance or reduce the heat transfer.

Liposomes are spherical vesicles enclosed by phospholipid bilayers. Nanoscale liposomes are widely employed for drug delivery in the pharmaceutical industry. In this study, nanoscale liposomes are fabricated using the microfluidic hydrodynamic focusing (MHF) approach, and the effects of flow rate ratio (FRR) on liposome size and drug loading efficiency are studied. Fluorescein isothiocyanate modified dextran is used as a hydrophilic drug simulant and Nile red is used as a hydrophobic drug simulant. The experiment results show that hydrophilic drug simulant loading efficiency increases as FRR increases and eventually plateaues at around 90% loading efficiency. The hydrophobic drug simulant loading efficiency and FRR have a positive linear correlation when FRR varies from 10 to 50. Concurrent loading of both hydrophilic and hydrophobic drug simulants maintains the same loading efficiencies as those of loading each drug simulant alone. A negative correlation between liposome size and FRR is also confirmed. Unloaded liposomes and hydrophilic drug-loaded liposomes are of the same sizes, and are smaller than the ones loaded with the hydrophobic drug simulants alone or combined. The results suggest tunable liposome size and drug loading efficiency with the MHF technique. This provides evidence to encourage further studies of microfluidic liposome fabrication in the pharmaceutical industry.

Interferometry-based, reflectometric, label-free biosensors have made significant progress in the analysis of molecular interactions after years of development. The design of interference substrates is a key research topic for these biosensors, and many studies have focused on porous films prepared by top-down methods such as porous silicon and anodic aluminum oxide. Lately, more research has been conducted on ordered porous layer interferometry (OPLI), which uses ordered porous colloidal crystal films as interference substrates. These films are made using self-assembly techniques, which is the bottom-up approach. They also offer several advantages for biosensing applications, such as budget cost, adjustable porosity, and high structural consistency. This review will briefly explain the fundamental components of self-assembled materials and thoroughly discuss various self-assembly techniques in depth. We will also summarize the latest studies that used the OPLI technique for label-free biosensing applications and divide them into several aspects for further discussion. Then, we will comprehensively evaluate the strengths and weaknesses of self-assembly techniques and discuss possible future research directions. Finally, we will outlook the upcoming challenges and opportunities for label-free biosensing using the OPLI technique.

A bstract We study the Schwinger effect during inflation and its imprints on the primordial power spectrum and bispectrum. The produced charged particles by Schwinger effect during inflation can leave a unique angular dependence on the primodial spectra.

A bstract We compute the albedo (or reflectivity) of electromagnetic waves off the electron-positron Hawking plasma that surrounds the horizon of a Quantum Black Hole. We adopt the “modified firewall conjecture” for fuzzballs [1, 2], where we consider significant electromagnetic interaction around the horizon. While prior work has treated this problem as an electron-photon scattering process, we find that the incoming quanta interact collectively with the fermionic excitations of the Hawking plasma at low energies. We derive this via two different methods: one using relativistic plasma dispersion relation, and another using the one-loop correction to photon propagator. Both methods find that the reflectivity of long wavelength photons off the Hawking plasma is significant, contrary to previous claims. This leads to the enhancement of the electromagnetic albedo for frequencies comparable to the Hawking temperature of black hole horizons in vacuum. We comment on possible observable consequences of this effect.

As a novel organic semiconductor derived from biomass, hydrothermal carbonation carbon (HTCC) usually exhibits an amorphous structure due to its well-recognized formation pathway based on 5-hydroxymethylfurfural (HMF), which impedes charge transfer and consequently restricts the photocatalytic activity. Herein, we report a crystalline HTCC photocatalyst produced via an unusual synthesis route applied to cellulose in the presence of an oxidant. Notably, the crystalline structure of cellulose was retained and became highly aromatized during the process, leading to significantly enhanced charge transfer efficiency and an increased density of active sites. Moreover, unlike other reported HTCC photocatalysis, the highly active hydrogen radicals (H•) were identified as the dominant active species governing photocatalytic Cr(VI) reduction over crystalline HTCC. As a result, this crystalline HTCC exhibited dramatically enhanced photocatalytic removal efficiencies of Cr(VI) and microcystin-LR (MC-LR) due to the highly efficient charge transfer, abundant active sites as well as highly active hydrogen radicals.

This study focuses on the correlative mechanism of the ambient pressure and inflow uniformity on the vortex and cavitation dynamics of an axial flow pump. The shear stress transport k - ω turbulence model and Schnerr-Sauer cavitation model are applied in the unsteady detached eddy simulation. The results show that the vortex merging between the primary and secondary tip leakage vortices (TLV) happens earlier with the growth of the cavity at a lower ambient pressure. The contact position of the merged TLV to the adjacent blade moves upstream with the decrease in the cavitation number. As the uniformity of the axial inflow decreases, TLV merging and vortex shedding are also promoted. The nonlinear variation of the initial angle of attack of the impeller blade leads to the compression or expansion of sheet cavitation under non-uniform inflow conditions. The evolution process and energy transfer of the vortices are verified quantitatively using a power spectral density analysis of kinetic energy fluctuations, and the short-wave instability leads to the fast decline of spectrum peaks at a higher frequency in the cavitating flow. It is crucial to avoid severe changes of ambient pressure and inflow uniformity to ensure the design performance of pump in actual working environment.