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Controlling thermal radiation is central in a range of applications including sensing, energy harvesting, and lighting. The thermal emission spectrum can be strongly modified through the electromagnetic local density of states (EM LDOS) in nanoscale-patterned metals and semiconductors. However, these materials become unstable at high temperature, preventing improvements in radiative efficiency and applications such as thermophotovoltaics. Here, we report stable high-temperature thermal emission based on hot electrons (>2000 K) in graphene coupled to a photonic crystal nanocavity, which strongly modifies the EM LDOS. The electron bath in graphene is highly decoupled from lattice phonons, allowing a comparatively cool temperature (700 K) of the photonic crystal nanocavity. This thermal decoupling of hot electrons from the LDOS-engineered substrate opens a broad design space for thermal emission control that would be challenging or impossible with heated nanoscale-patterned metals or semiconductor materials. Efficient control of thermal radiation is at the core of device design for a variety of applications. Here, the authors demonstrate a high-temperature thermal emitter with selective emission from a graphene-silicon photonic crystal nanocavity.

The Hofstadter energy spectrum provides a uniquely tunable system to study emergent topological order in the regime of strong interactions. Previous experiments, however, have been limited to low Bloch band fillings where only the Landau level index plays a role. We report measurements of high-mobility graphene superlattices where the complete unit cell of the Hofstadter spectrum is accessible. We observed coexistence of conventional fractional quantum Hall effect (QHE) states together with the integer QHE states associated with the fractal Hofstadter spectrum. At large magnetic field, we observed signatures of another series of states, which appeared at fractional Bloch filling index. These fractional Bloch band QHE states are not anticipated by existing theoretical pictures and point toward a distinct type of many-body state.

A device is presented that can detect mid-infrared plasmons in graphene encapsulated by hexagonal boron nitride via the thermoelectric effect; the natural decay product of the plasmons (electronic heat) is converted into a measurable voltage signal. Controlling, detecting and generating propagating plasmons by all-electrical means is at the heart of on-chip nano-optical processing 1 , 2 , 3 . Graphene carries long-lived plasmons that are extremely confined and controllable by electrostatic fields 4 , 5 , 6 , 7 ; however, electrical detection of propagating plasmons in graphene has not yet been realized. Here, we present an all-graphene mid-infrared plasmon detector operating at room temperature, where a single graphene sheet serves simultaneously as the plasmonic medium and detector. Rather than achieving detection via added optoelectronic materials, as is typically done in other plasmonic systems 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , our device converts the natural decay product of the plasmon—electronic heat—directly into a voltage through the thermoelectric effect 16 , 17 . We employ two local gates to fully tune the thermoelectric and plasmonic behaviour of the graphene. High-resolution real-space photocurrent maps are used to investigate the plasmon propagation and interference, decay, thermal diffusion, and thermoelectric generation.

Near-field photocurrent nanoscopy is used for imaging strongly confined terahertz graphene plasmons with linear dispersion. Terahertz (THz) fields are widely used for sensing, communication and quality control 1 . In future applications, they could be efficiently confined, enhanced and manipulated well below the classical diffraction limit through the excitation of graphene plasmons (GPs) 2 , 3 . These possibilities emerge from the strongly reduced GP wavelength, λ p , compared with the photon wavelength, λ 0 , which can be controlled by modulating the carrier density of graphene via electrical gating 4 , 5 , 6 , 7 , 8 . Recently, GPs in a graphene/insulator/metal configuration have been predicted to exhibit a linear dispersion (thus called acoustic plasmons) and a further reduced wavelength, implying an improved field confinement 9 , 10 , 11 , analogous to plasmons in two-dimensional electron gases (2DEGs) near conductive substrates 12 . Although infrared GPs have been visualized by scattering-type scanning near-field optical microscopy (s-SNOM) 6 , 7 , the real-space imaging of strongly confined THz plasmons in graphene and 2DEGs has been elusive so far—only GPs with nearly free-space wavelengths have been observed 13 . Here we demonstrate real-space imaging of acoustic THz plasmons in a graphene photodetector with split-gate architecture. To that end, we introduce nanoscale-resolved THz photocurrent near-field microscopy, where near-field excited GPs are detected thermoelectrically 14 rather than optically 6 , 7 . This on-chip detection simplifies GP imaging as sophisticated s-SNOM detection schemes can be avoided. The photocurrent images reveal strongly reduced GP wavelengths ( λ p  ≈  λ 0 /66), a linear dispersion resulting from the coupling of GPs with the metal gate below the graphene, and that plasmon damping at positive carrier densities is dominated by Coulomb impurity scattering.

This study addresses the problems of poor dynamic stability, high vibration coupling, and inefficient energy use in large-farm manure handling machines. A profiling wheel-based multi-disciplinary approach is proposed in the study. With the rocker arm prototype, double-ball heads, and a hydraulic damping system, a parametric design is built that includes vibration and energy consumption. The simulation results in EDEM2022 and ANSYS2022 prove the structure viability and motion compensation capability, while NSGA-II optimizes the damping parameters (k1 = 380 kN/m, C = 1200 Ns/m). The results show a 14.7% σFc reduction, 14.3% αRMS decrease, resonance avoidance (14–18 Hz), Δx (horizontal offset of the frame) < 5 mm, 18% power loss to 12.5%, and 62% stability improvement. The new research includes constructing a dynamic model by combining the Hertz contact theory with the modal decoupling method, while interacting with an automatic algorithm of adaptive damping and a mechanical-hydraulic-control-oriented optimization platform. Future work could integrate lightweight materials and multi-machine collaboration for smarter, greener manure cleaning.

Optoelectronic devices utilizing graphene have demonstrated unique capabilities and performances beyond state-of-the-art technologies. However, requirements in terms of device quality and uniformity are demanding. A major roadblock towards high-performance devices are nanoscale variations of the graphene device properties, impacting their macroscopic behaviour. Here we present and apply non-invasive optoelectronic nanoscopy to measure the optical and electronic properties of graphene devices locally. This is achieved by combining scanning near-field infrared nanoscopy with electrical read-out, allowing infrared photocurrent mapping at length scales of tens of nanometres. Using this technique, we study the impact of edges and grain boundaries on the spatial carrier density profiles and local thermoelectric properties. Moreover, we show that the technique can readily be applied to encapsulated graphene devices. We observe charge build-up near the edges and demonstrate a solution to this issue. Graphene grain boundaries and charge inhomogeneities limit its electronic properties. Here the authors combine scanning near-field optical microscopy with electrical read-out to image these defects at the nanoscale under an encapsulation layer, and show that charges build up along the edges of the flake.

Captive otters fed with different diets possessed distinct gut microbial communities and functions, with the enrichment of several pathogens and multiple resistance genes in their gut microbiota. The current artificial feeding strategies had the possibility to accelerate the colonization and proliferation of various pathogenic bacteria in the intestines of otters and the spread of resistance genes, increasing the risk of diseases. In addition, supplementation with commercial cat food had benefits for otters’ intestinal fermentation and the metabolism of gut microbiota.

Background Hepatitis C virus (HCV) infection is a public health issue for which an effective universal screening method is urgently needed. An oral anti-HCV test could provide a noninvasive and rapid screening strategy for HCV infection. This study evaluated the performance of a new point-of-care oral assay developed by Well for the detection of HCV antibody. Methods Individuals from three centers with and without HCV infection were enrolled. All participants were tested for oral HCV antibody using the Well assay and for serum HCV antibody using established tests (ARCHITECT i2000 anti-HCV assay and InTec serum anti-HCV assay). For participants who obtained positive results, HCV RNA was tested for verification. Some patients underwent the OraQuick HCV test at the same time, and some self-tested with the Well assay during the same period. Results A total of 1179 participants, including 486 patients with chronic HCV infection, 108 patients with other liver diseases, and 585 individuals who underwent physical examination, were enrolled. The Well anti-HCV test had a sensitivity of 91.88% (95% confidence interval [CI]: 88.97–94.09%) and a specificity of 98.00% (96.58–98.86%) for oral HCV antibody detection. The consistency between the Well and InTec assays was 97.02% (1138/1179). The consistency between the Well and OraQuick assays was 98.50% (197/200). Furthermore, the results of self-testing were highly consistent with those of researcher-administered tests (Kappa = 0.979). In addition, the HCV RNA results also showed that HCV RNA could only be detected on 1 of the 39 false-negative samples, and for 172 positive HCV RNA results, 171 could be detected by the Well oral anti-HCV assay. Conclusions The Well oral anti-HCV test offers high sensitivity and specificity and performed comparably to both the OraQuick assay and InTec assay for HCV diagnosis. Thus, the Well test represents a new tool for universal HCV screening to identify infected patients, particularly in regions with limited medical resources.

Hepatitis B virus (HBV) and hepatitis C virus (HCV) co-infections contributes to a substantial proportion of liver disease worldwide. The aim of this study was to assess the clinical and virological features of HBV-HCV co-infection. Demographic data were collected for 3238 high-risk people from an HCV-endemic region in China. Laboratory tests included HCV antibody and HBV serological markers, liver function tests, and routine blood analysis. Anti-HCV positive samples were analyzed for HCV RNA levels and subgenotypes. HBsAg-positive samples were tested for HBV DNA. A total of 1468 patients had chronic HCV and/or HBV infections. Among them, 1200 individuals were classified as HCV mono-infected, 161 were classified as HBV mono-infected, and 107 were classified as co-infected. The HBV-HCV co-infected patients not only had a lower HBV DNA positive rate compared to HBV mono-infected patients (84.1% versus 94.4%, respectively; P < 0.001). The median HCV RNA levels in HBV-HCV co-infected patients were significantly lower than those in the HCV mono-infected patients (1.18[Interquartile range (IQR) 0-5.57] versus 5.87[IQR, 3.54-6.71] Log10 IU/mL, respectively; P < 0.001). Furthermore, co-infected patients were less likely to have detectable HCV RNA levels than HCV mono-infected patients (23.4% versus 56.5%, respectively; P < 0.001). Those HBV-HCV co-infected patients had significantly lower median HBV DNA levels than those mono-infected with HBV (1.97[IQR, 1.3-3.43] versus 3.06[IQR, 2-4.28] Log10 IU/mL, respectively; P < 0.001). The HBV-HCV co-infection group had higher ALT, AST, ALP, GGT, APRI and FIB-4 levels, but lower ALB and total platelet compared to the HBV mono-infection group, and similar to that of the HCV mono-infected group. These results suggest that co-infection with HCV and HBV inhibits the replication of both viruses. The serologic results of HBV-HCV co-infection in patients suggests more liver injury compared to HBV mono-infected patients, but is similar to HCV mono-infection.

Light properties in the mid-infrared can be controlled at a deep subwavelength scale using hyperbolic phonons-polaritons of hexagonal boron nitride. While propagating as waveguided modes hyperbolic phonons-polaritons can concentrate the electric field in a chosen nano-volume. Such a behavior is at the heart of many applications including subdiffraction imaging and sensing. Here we employ HPPs in heterostructures of hexagonal boron nitride and graphene as new nano-optoelectronic platform by uniting the benefits of efficient hot-carrier photoconversion in graphene and the hyperbolic nature of hexagonal boron nitride. We demonstrate electrical detection of hyperbolic phonons-polaritons by guiding them towards a graphene pn-junction. We shine a laser beam onto a gap in metal gates underneath the heterostructure, where the light is converted into hyperbolic phonons-polaritons. The hyperbolic phonons-polaritons then propagate as confined rays heating up the graphene leading to a strong photocurrent. This concept is exploited to boost the external responsivity of mid-infrared photodetectors, overcoming the limitation of graphene pn-junction detectors due to their small active area and weak absorption. Moreover this type of detector exhibits tunable frequency selectivity due to the hyperbolic phonons-polaritons, which combined with its high responsivity paves the way for efficient high-resolution mid-infrared imaging. Optoelectronics: guided hyperbolic phonon-polaritons in h-BN boost mid-infrared graphene photodetectors h-BN hyperbolic phonon-polaritons can be probed electrically in a van der Waals photodetector by guiding them towards a graphene junction. A team led by F.H.L. Koppens at ICFO developed a nano-optoelectronic device whereby light from a laser beam, shone on a heterostructure of monolayer graphene encapsulated in h-BN, is converted to hyperbolic phonon-polaritons. Once the latter are launched at the edge of a metallic bottom split gate, they propagate as highly confined and directional rays towards graphene, where they are absorbed. This results in the generation of hot carriers which diffuse spatially towards the graphene junction, giving rise to an inhomogeneous temperature distribution which, in turn, leads to a strong photo-response. Besides enhanced responsivity and room temperature operation, this mid-infrared photodetector possesses tunable frequency selectivity, making it appealing for imaging and sensing applications.