Creation of memory-memory entanglement in a metropolitan quantum network.

Towards realizing the future quantum internet1,2, a pivotal milestone entails the transition from two-node proof-of-principle experiments conducted in laboratories to comprehensive multi-node set-ups on large scales. Here we report the creation of memory-memory entanglement in a multi-node quantum network over a metropolitan area. We use three independent memory nodes, each of which is equipped with an atomic ensemble quantum memory3 that has telecom conversion, together with a photonic server where detection of a single photon heralds the success of entanglement generation. The memory nodes are maximally separated apart for 12.5 kilometres. We actively stabilize the phase variance owing to fibre links and control lasers. We demonstrate concurrent entanglement generation between any two memory nodes. The memory lifetime is longer than the round-trip communication time. Our work provides a metropolitan-scale testbed for the evaluation and exploration of multi-node quantum network protocols and starts a stage of quantum internet research.

Melatonin enhances resistance to Botryosphaeria dothidea in pear by promoting jasmonic acid and phlorizin biosynthesis.

Ring rot, caused by Botryosphaeria dothidea, is an important fungal disease of pear fruit during postharvest storage. Melatonin, as a plant growth regulator, plays an important role in enhancing the stress resistance of pear fruits. It enhances the resistance of pear fruits to ring rot by enhancing their antioxidant capacity. However, the underlying mechanism remains unclear. In this study, we examined the effect of melatonin on the growth of B. dothidea. Results showed that melatonin did not limit the growth of B. dothidea during in vitro culture. However, metabolomics and transcriptomics analyses of 'Whangkeumbae' pear (Pyrus pyrifolia) revealed that melatonin increased the activity of antioxidant enzymes, including peroxidase (POD), superoxide dismutase (SOD), and polyphenol oxidase (PPO), in the fruit and activated the phenylpropanoid metabolic pathway to improve fruit resistance. Furthermore, melatonin treatment significantly increased the contents of jasmonic acid and phlorizin in pear fruit, both of which could improve disease resistance. Jasmonic acid regulates melatonin synthesis and can also promote phlorizin synthesis, ultimately improving the resistance of pear fruit to ring rot. In summary, the interaction between melatonin and jasmonic acid and phlorizin enhances the antioxidant defense response and phenylpropanoid metabolism pathway of pear fruit, thereby enhancing the resistance of pear fruit to ring rot disease. Our results provide new insights into the application of melatonin in the resistance to pear fruit ring rot.

Polarized vortex Smith-Purcell radiation with cascaded metasurfaces.

We introduce the concept of polarized vortex Smith-Purcell radiation by the interaction of an electron beam and cascaded metasurfaces. The spin and orbital angular momenta of Smith-Purcell radiation are determined by the cascaded metasurface that consists of a grating and a phase gradient metasurface. The grating converts the electron beam radiation into the desired polarized light, while the phase gradient metasurface generates the vortex light. Furthermore, the vortex Smith-Purcell radiation with linear and circular polarizations can be achieved by the various cascaded metasurfaces. In particular, the conversion of chirality in the Smith-Purcell radiation carrying circular polarization is accompanied by the alteration of positive and negative topological charges. This work paves the way for generating polarized vortex electron radiation and is beneficial to promote the development of free-electron-driven devices.

Bound states in the continuum in asymmetric one-dimensional photonic crystal systems guided by anisotropy.

Bound states in the continuum (BICs) have been widely observed in many symmetric geometries in the optical system during the last decade. Here, we consider a scenario in which the structure is designed asymmetrically with anisotropic birefringent material embedded in one-dimensional photonic crystals. This kind of new shape opens the possibility of obtaining symmetry-protected BICs (SP-BICs) and Friedrich-Wintgen BICs (FW-BICs) form in tunable anisotropy axis tilt. Interestingly, these BICs can be observed as high-Q resonances by variation of the system's parameters, such as the incident angle, which means the structure without being injected at Brewster's angle can also achieve BICs. Our findings might achieve active regulation and are easy to manufacture.

Annular and unidirectional transverse scattering with high directivity based on magnetoelectric coupling.

Transverse scattering is a special directional scattering perpendicular to the propagation direction, which has attracted great interest due to its potential applications from directional antennas, optical metrology to optical sensing. Here we reveal annular transverse scattering and unidirectional transverse scattering by magnetoelectric coupling of Omega particle. The annular transverse scattering can be achieved by the longitudinal dipole mode of the Omega particle. Furthermore, we demonstrate the highly asymmetric unidirectional transverse scattering by adjusting the transverse electric dipole (ED) and longitudinal magnetic dipole (MD) modes. Meanwhile, the forward scattering and backward scattering are suppressed by the interference of transverse ED and longitudinal MD modes. In particular, the lateral force exerted on the particle is accompanied by the transverse scattering. Our results provide a useful toolset for manipulating light scattered by the particle and broaden the application range of the particle with magnetoelectric coupling.

Andrographolide contributes to the attenuation of cardiac hypertrophy by suppressing endoplasmic reticulum stress.

CONTEXT: Andrographolide (Andr) is a bioactive Andr diterpenoid extracted from herbaceous Andrographis paniculata (Burm. F.) Wall. ex Nees (Acanthaceae). Andr can relieve cardiac dysfunction in mice by inhibiting the mitogen-activated protein kinases (MAPK) pathway. OBJECTIVE: This study investigates the efficacy and underlying mechanism of Andr on cardiac hypertrophy in mice. MATERIALS AND METHODS: Male C57 mice (20-25 g, 6-8 weeks) were divided into four groups (n = 10 mice/group) as sham group (sham operation), transverse aortic constriction (TAC) model group, TAC + Andr 100 mg/kg group and TAC + Andr 200 mg/kg group. Andr groups were given intragastric administration of Andr (100 and 200 mg/kg) once a day for 14 consecutive days. An in vitro hypertrophy model was established by adding 1 µM of Ang II to H9c2 cells for 48 h induction. RESULTS: In TAC-mice, Andr improved echocardiographic indices [reduced LVESD (30.4% or 37.1%) and LVEDD (24.8% or 26.4%), increased EF (22.9% or 42.6%) and FS (25.4% or 52.2%)], reduced BNP (11.5% or 23.6%) and Ang II levels (10.3% or 32.8%), attenuates cardiac fibrosis and reduces cardiac cell apoptosis in TAC mice. In vitro, Andr attenuated cardiomyocyte hypertrophy and decreased the protein expression of GRP78 (67.8%), GRP94 (47.6%), p-PERK (44.9%) and CHOP (66.8%) in Ang-II-induced H9c2 cells and reversed after endoplasmic reticulum (ER) stress agonist Tunicamycin (TN) treatment. DISCUSSION AND CONCLUSIONS: Andr was found to be an anti-hypertrophic regulator, which could attenuate cardiac hypertrophy by suppressing ER stress. It may be a new therapeutic drug for cardiac hypertrophy.

Alleviation of iron deficiency in pear by ammonium nitrate and nitric oxide.

BACKGROUND: Iron is essential for the growth and development of trace elements in plants, and iron deficiency can lead to leaf chlorosis. Ammonium and nitrate are the major forms of nitrogen present in soils. Ammonium nitrate alleviates the chlorosis of leaves caused by iron deficiency, but the mechanism is not clear in pear. RESULTS: Ammonium nitrate induced the increase of nitric oxide (NO) under iron deficiency. We further analyzed the effect of NO by exogenous NO treatment. The results showed that ammonium nitrate and NO increased the activity of ferric chelate reductase. NO induced the expression of multiple IRT genes and promoted the transmembrane transport of irons. Ammonium nitrate and NO promoted the activity of nitrogen assimilation-related enzymes and the nitrogen absorption capacity, and they also increased glutamine synthetase activity. Finally, ammonium nitrate and NO increased chlorophyll synthesis, with subsequent increase in the photosynthetic capacity of plants and accumulation of biomass. CONCLUSION: Ammonium nitrate indirectly alleviates the symptoms of plant yellowing by promoting the increase of NO, which increases the response of iron transporters. Both substances increase the nitrogen accumulation in plants. This study demonstrates a new option for minimizing Fe deficiency by regulating the balance between nutrients.

Diverse lateral shifts of beams in non-Hermitian waveguide arrays.

Non-Hermitian systems have attracted considerable attention in optics due to the rich physics introduced by the existence of real spectra and exceptional points (EPs), which is exploited in lasers, optical sensors and on-chip manipulations of light. Here, focusing on the dynamics of beams in non-Hermitian waveguide arrays supporting a ring of EPs (exceptional ring) and 3rd-order EPs, we theoretically demonstrate that the center of energy of a beam prepared around an eigenstate of the waveguide array near EPs could exhibit non-zero shifts in the lateral direction during its propagation. When the initial state of the beam prepared around an eigenstate inside (outside) the exceptional ring with the imaginary (real) eigenvalue, the lateral shifts of the beams are manifested by the non-oscillating (Zitterbewegung-like) motions, which are robust to the perturbations of coupling coefficients between waveguides. Remarkably, the amplitude of the non-oscillating shift is dependent on a non-Hermitian Berry connection (U(1) gauge invariance). It contradicts the conventional wisdom that the Berry connection cannot induce the dynamic effect. Furthermore, near the high-order EPs, the initial-state-dependent lateral shifts of the beams present diversity, such as multifrequencies and destructive interferences. The counterintuitive lateral shifts of the beams stem from the non-orthogonal nature of eigenstate of the non-Hermitian systems, which may open a gateway towards the non-Hermitian beam dynamics and manipulations of beams.

Reconstructing subwavelength resolution terahertz holographic images.

Computer-generated holography typically generates terahertz (THz) holographic images with a pixel size larger than wavelength. We propose a multi-foci metalens model to reconstruct THz holographic images with subwavelength resolution. The designed devices are realized based on dielectric metasurfaces consisting of silicon micropillars with spatially variant orientations. By exploiting quasi-continuous profile of focal points as the pixels of a holographic image, a metalens can reconstruct a high-resolution target image on its focal plane. The effects of size and pitch of each sub-diffraction focal point on imaging quality and pixel resolution are discussed. The intensity distribution at each focal point indicates that the reconstructed images have subwavelength resolution. In comparison with conventional hologram designs, this design method can be used to reconstruct THz holographic images with subwavelength resolution, which have potential applications in THz communication, information security and anti-counterfeiting.

Fourier single pixel imaging reconstruction method based on the U-net and attention mechanism at a low sampling rate.

There exists the contradiction between imaging efficiency and imaging quality for Fourier single-pixel imaging (FSI). Although the deep learning approaches have solved this problem to some extent, the reconstruction quality at low sampling rate is still not enough to meet the practical requirements. To solve this problem, inspired by the idea of super-resolution, this paper proposes the paralleled fusing of the U-net and attention mechanism to improve the quality of FSI reconstruction at a low sampling rate. This paper builds a generative adversarial network structure to achieve recovery of high-resolution target images from low-resolution FSI reconstruction results under low sampling rate conditions. Compared with conventional FSI and other deep learning methods based on FSI, the proposed method can get better quality and higher resolution results at low sampling rates in simulation and experiments. This approach is particularly important to high-speed Fourier single pixel imaging applications.

Topologically Enabled Ultrahigh-Q Chiroptical Resonances by Merging Bound States in the Continuum.

Ultrahigh-Q chiroptical resonance metasurfaces based on merging bound states in the continuum (BICs) are investigated and numerically demonstrated. The destruction of C2 symmetry results in the leakage of BICs into quasi-BICs, and a chiral quasi-BIC is obtained by oblique incidence or continuous destruction of the mirror symmetry of the structure. Due to the significant topological properties of merging BICs, the Q factor (over 2 × 105) of the chiral resonance peak obtained is much higher than that of the previous work. Moreover, the proposed structure is easy to fabricate because no additional out-of-plane asymmetry is introduced. The proposed scheme is of importance in chiral biosensing applications.

Postselected Entanglement between Two Atomic Ensembles Separated by 12.5 km.

Quantum internet gives the promise of getting all quantum resources connected, and it will enable applications far beyond a localized scenario. A prototype is a network of quantum memories that are entangled and well separated. In this Letter, we report the establishment of postselected entanglement between two atomic quantum memories physically separated by 12.5 km directly. We create atom-photon entanglement in one node and send the photon to a second node for storage via electromagnetically induced transparency. We harness low-loss transmission through a field-deployed fiber of 20.5 km by making use of frequency down-conversion and up-conversion. The final memory-memory entanglement is verified to have a fidelity of 90% via retrieving to photons. Our experiment makes a significant step forward toward the realization of a practical metropolitan-scale quantum network.

Placing a New Filter before Removing Embolized Nonconical Filter: A Report of 13 Cases.

OBJECTIVES: Permanent filter placement may result in numerous complications. Filter removal is recommended if there are no risks of pulmonary embolism. This study aimed to explore the feasibility of placing a new filter when the embolized nonconical filter is removed. METHODS: This study included patients who had received a new filter between 2018 and 2019 before the nonconical filters were removed. Patient characteristics, new filter types, thrombus interception rate, filter removal rate, feasibility, and safety were analyzed retrospectively. Feasibility was defined as the successful placement of new filters and the removal of the nonconical filters. Safety was defined as the absence of symptomatic pulmonary embolism and inferior vena cava hemorrhage after removing the nonconical filters, as well as the successful removal of new filters without symptomatic pulmonary embolism. RESULTS: The average indwelling period of the nonconical filters was 29 (range, 17-30) days among the 13 patients. The removal rate of the nonconical filters was 100%. Five patients (38.5%) received new Denali filters, one (7.7%) received a new Celect filter, and 7 (53.8%) received new temporary filters. Thrombi were intercepted in 10 of the patients (76.9%). The removal rate of the replaced new filters was 100%. No rupture or shifting of the new filters occurred. No symptomatic pulmonary embolism was found after the removal of both the nonconical filters and the new filters. The patients were followed up for 3 months after the surgeries, and the inferior vena cavae of 12 (92.3%) patients were patent, and no new embolic events were found. CONCLUSIONS: Placing a new replacement filter before removal of the embolized nonconical filter may be a feasible approach to prevent pulmonary embolism. Both the nonconical filter and the new filter could be removed subsequently after the thrombi were treated.

Metalens for Generating a Customized Vectorial Focal Curve.

Three-dimensional (3D) light fields with spatially inhomogeneous polarization and intensity distributions play an increasingly important role in photonics due to their peculiar optical features and extra degrees of freedom for carrying information. However, it is very challenging to simultaneously control the intensity profile and polarization profile in an arbitrary manner. Here we experimentally demonstrate a metalens that can focus light into an arbitrarily shaped focal curve with a predefined polarization distribution. The efficacy of this approach is exemplified through the demonstration of focused curves in 3D space ranging from simple shapes such as a circle to topologically nontrivial objects such as a 3D knot with controlled local polarization states. This powerful control of the light field would be technically challenging with their conventional counterparts. Our demonstration may find applications in beam engineering and integration optics.

Bagging Strategy and Identification of Coloring Mode of 'Xinqihong' Pear.

'Xinqihong' is a recently selected and well-colored red pear (Pyrus bretschneideri Rehd.) cultivar that is popular in the marketplace owing to the bright red color and high quality of the fruit. The red pigmentation is strongly associated with the light signal. However, its responses to bagging treatment and to light exposure after shading are unknown. In this study, the fruit were treated with three types of fruit bags. 'Xinqihong' fruit colored rapidly in response to light stimulation. A white fruit bag was optimal for bagging of 'Xinqihong' fruit. To ensure satisfactory red pigmentation, the fruit required exposure to 30 days of light after bag removal. A transcriptome analysis was conducted to screen light-signal-related genes and identify their possible functions. PbCRY1 activated the promoter of PbHY5.2 and enhanced its expression. PbHY5.2 activated the promoter activity of PbUFGT and induced anthocyanin synthesis, and also showed self-activation characteristics. Both PbCRY2 and PbPHY1 induced anthocyanin accumulation. Thus, blue-light receptors played an important role in anthocyanin synthesis. This study provides a theoretical basis for the bagging cultivation of new varieties of 'Xinqihong', and lays a foundation for the study of the mechanisms of red pear fruit coloring in response to light signals.

Chiral and multiple one-way surface states on photonic gyroelectric metamaterials with small Chern number.

Topological one-way surface states allow light to pass through sharp corners without reflection. In order to enhance the capability of surface routing devices, multiple one-way surface modes are usually required. Different from previously reported multiple surface modes achieved with large Chern number photonic media, we realize multiple surface waves on a continuous medium with small Chern number, i.e., |C| = 1. The new topological phase is found when the hyperbolic and double semi-ellipsoid-like cone bands are simultaneously gapped by vacuum state. We also find the degeneracy of multiple one-way surface waves in the double semi-ellipsoid-like metamaterials. The propagation direction of the waves is determined by their own ellipticities. Our results may help to construct surface state devices with multiplexing capability and higher coupling efficiency.

Recent Progress in the Development of Graphene Detector for Terahertz Detection.

Terahertz waves are expected to be used in next-generation communications, detection, and other fields due to their unique characteristics. As a basic part of the terahertz application system, the terahertz detector plays a key role in terahertz technology. Due to the two-dimensional structure, graphene has unique characteristics features, such as exceptionally high electron mobility, zero band-gap, and frequency-independent spectral absorption, particularly in the terahertz region, making it a suitable material for terahertz detectors. In this review, the recent progress of graphene terahertz detectors related to photovoltaic effect (PV), photothermoelectric effect (PTE), bolometric effect, and plasma wave resonance are introduced and discussed.

Genome-Wide Analysis of RAV Transcription Factors and Functional Characterization of Anthocyanin-Biosynthesis-Related RAV Genes in Pear.

Related to ABSCISIC ACID INSENSITIVE3/VIVIPAROUS1 (ABI3/VP1, RAV), transcription factors (TFs) belonging to the APETALA2/ETHYLENE RESPONSIVE FACTOR (AP2/ERF) TF family play critical roles in plant growth, development, and responses to abiotic and biotic stress. In this study, 11 novel RAV TFs were identified in pear (Pyrus bretschneideri Rehd). A phylogenetic analysis revealed that the TFs clustered into three groups with 10 conserved motifs, some of which were group- or subgroup-specific, implying that they are important for the functions of the RAVs in these clades. RAVs in Pyrus and Malus were closely related, and the former showed a collinear relationship. Analysis of their expression patterns in different tissues and at various growth stages and their responses to abiotic and biotic stress suggested that PbRAV6 and PbRAV7 play important roles in drought stress and salt stress, respectively. We investigated the function of RAVs in pear peel coloration using two red pear varieties with different color patterns and applying data from transcriptome analyses. We found that PbRAV6 participates in the regulation of pericarp color. These findings provide insight into a new TF family in pear and a basis for further studies on the response to drought stress and fruit coloration in this commercially important crop.

[The myocardial protective effect of propofol on rats with experimental myocardial infarction and its mechanism].

The aim of the present study was to investigate the protective effect of propofol on the experimental myocardial infarction in rats. The myocardial infarction model was established by ligating the anterior descending branch of left coronary artery in rats. Model rats were treated with propofol. Cardiac function was evaluated by echocardiography. Cardiac hemodynamic changes were detected by multiconductor biorecorder. Pathological changes in the infarcted myocardia were detected by HE staining. The expression levels of cardiac hypertrophy marker genes and fibrosis marker proteins were analyzed by real-time quantitative PCR and Western blot. The results showed that, compared with the sham surgery group, the model group exhibited larger infarct size (> 40%), impaired heart function, and significantly increased left ventricular end-diastolic pressure (LVEDP). Propofol reduced cardiac function impairment and decreased LVEDP in the model group. Propofol significantly reduced lung weight/body weight ratio, heart weight/body weight ratio, left ventricular weight/body weight ratio and left atrial weight/body weight ratio in the model group. Furthermore, after myocardial infarction, the administration of propofol significantly improved the diastolic strain rate, down-regulated the mRNA expression levels of myocardial hypertrophy markers, atrial natriuretic peptide and ß-myosin heavy chain, and reversed the up-regulation of matrix metalloproteinase 2 (MMP2), MMP9 and tissue inhibitor of metalloproteinase-2 (TIMP-2) induced by myocardial infarction. These results suggest propofol can reduce adverse ventricular remodeling, cardiac dysfunction, myocardial hypertrophy and fibrosis after myocardial infarction, and has protective effect against the experimental myocardial infarction induced by coronary artery ligation in rats.

Multi-foci metalens for terahertz polarization detection.

We propose a reflective terahertz (THz) metalens with four focal points for polarization detection of THz beams. The metalens is composed of Z-shaped resonators with spatially variant orientations, a reflective gold layer, and a dielectric spacer between them. The polarization states of the focal points include left circular polarization, right circular polarization, an incident polarization state, and a polarization state whose major axis is rotated π/4 in comparison with that of the incident polarization. The handedness, ellipticity, and major axis of the polarization state can be determined based on the light intensities of the focal points. The uniqueness of the designed device renders this technique very attractive for applications in compact THz polarization detection and information processing.