Search

The number of semiconducting MXenes with direct band gaps is extremely low; thus, it is highly desirable to broaden the MXene family beyond carbides and nitrides to expand the palette of desired chemical and physical properties. Here, we theoretically report the existence of the single-layer (SL) dititanium oxide 2H-Ti

Constructing two-dimensional (2D) van der Waals (vdW) heterostructures is an effective strategy for tuning and improving the characters of 2D-material-based devices. Four trilayer vdW heterostructures, BP/BP/MoS2, BlueP/BlueP/MoS2, BP/graphene/MoS2 and BlueP/graphene/MoS2, were designed and simulated using the first-principles calculation. Structural stabilities were confirmed for all these heterostructures, indicating their feasibility in fabrication. BP/BP/MoS2 and BlueP/BlueP/MoS2 lowered the bandgaps further, making them suitable for a greater range of applications, with respect to the bilayers BP/MoS2 and BlueP/MoS2, respectively. Their absorption coefficients were remarkably improved in a wide spectrum, suggesting the better performance of photodetectors working in a wide spectrum from mid-wave (short-wave) infrared to violet. In contrast, the bandgaps in BP/graphene/MoS2 and BlueP/graphene/MoS2 were mostly enlarged, with a specific opening of the graphene bandgap in BP/graphene/MoS2, 0.051 eV, which is much larger than usual and beneficial for optoelectronic applications. Accompanying these bandgap increases, BP/graphene/MoS2 and BlueP/graphene/MoS2 exhibit absorption enhancement in the whole infrared, visible to deep ultraviolet or solar blind ultraviolet ranges, implying that these asymmetrically graphene-sandwiched heterostructures are more suitable as graphene-based 2D optoelectronic devices. The proposed 2D trilayer vdW heterostructures are prospective new optoelectronic devices, possessing higher performance than currently available devices.

MgAlON transparent ceramic was prepared via pressureless sintering and post hot isostatic pressing. The in-line transmittance of MgAlON ceramic exceeds 80% in the range 0.39–4.67 μm, and the ceramic was fully dense with average grain sizes ∼55 μm. The mechanical properties at the grain boundary (GB) and the center of the grain (CG) of MgAlON ceramic was investigated by nanoindentation at forces of 1 × 102–3 × 105 μN. The results indicated that the hardness values of MgAlON ceramic were sensitive to the testing forces and measurements position. The hardness at GB zone was lower than that at CG zone, which was probably ascribed to weaker interatomic bonding force in GB area. The Meyer's index of the hardness in GB and CG regions is 1.87 and 1.82, respectively. There is a weaker ISE in GB area of MgAlON as a result of larger plasticity and smaller elasticity. The hardness values of GB and CG regions are ∼13.36 GPa and ∼13.58 GPa, respectively.

Data supplementation and interpretation

The coexistence of quantum and classical light in the same fiber link is extremely desired in developing quantum communication. It has been implemented for different quantum information tasks, such as classical light coexisting with polarization-entangled photons at telecom O-band, and with quantum signal based quantum key distribution (QKD). In this work, we demonstrate the coexistence of energy-time entanglement based QKD and fiber optical communication at the telecom C-band. The property of noise from the classical channel is characterized with classical light at different wavelengths. With the largest noise, i.e., the worst case, the properties of energy-time entanglement are measured at different fiber optical communication rates. By measuring the two-photon interference of energy-time entanglement, our results show that a visibility of 82.01$\pm$1.10\% is achieved with a bidirectional 20 Gbps fiber optical communication over 40 km. Furthermore, by performing the BBM92 protocol for QKD, a secret key rate of 245 bits per second could be generated with a quantum bit error rate of 8.88\% with the coexisted energy-time entanglement.~Our demonstration paves the way for developing the infrastructure for quantum networks compatible with fiber optical communication., Comment: 6 pages, 3 figures

Multi-wavelength quantum light sources, especially at telecom band, are extremely desired in quantum information technology. Despite recent impressive advances, such a quantum light source with high quality remains challenging. Here we demonstrate a multi-wavelength quantum light source using a silicon nitride micro-ring with a free spectral range of 200 GHz. The generation of eight pairs of correlated photons is ensured in a wavelength range of 25.6 nm. With device optimization and noise-rejecting filters, our source enables the generation of heralded single-photons - at a rate of 62 kHz with $g^{(2)}_{h}(0)=0.014\pm0.001$, and the generation of energy-time entangled photons - with a visibility of $99.39\pm 0.45\%$ in the Franson interferometer. These results, at room temperature and telecom wavelength, in a CMOS compatible platform, represent an important step towards integrated quantum light devices for the quantum networks., 7 pages, 4 figures

To advance the full potential of quantum networks one should be able to distribute quantum resources over long distances at appreciable rates. As a consequence, all components in the networks need to have large multimode capacity to manipulate photonic quantum states. Towards this end, a multimode photonic quantum memory, especially one operating at telecom wavelength, remains a key challenge. Here we demonstrate a spectro-temporally multiplexed quantum memory at 1532 nm. Multimode quantum storage of telecom-band heralded single photons is realized by employing the atomic frequency comb protocol in a 10-m-long cryogenically cooled erbium doped silica fibre. The multiplexing encompasses five spectral channels - each 10 GHz wide - and in each of these up to 330 temporal modes, resulting in the simultaneous storage of 1650 modes of single photons. Our demonstrations open doors for high-rate quantum networks, which are essential for future quantum internet.

Recently, two-dimensional (2D) metal halides have brought out an intensive interest for their unique mechanical, electronic, magnetic, and topological properties. Here, we theoretically report the existence of the single-layer (SL) zirconium dihalide materials ZrX2 (X = Cl, Br, and I) using first-principles calculations. SL ZrX2, which can be obtained from its bulk phase through simple mechanical exfoliation, shows the dynamic, thermodynamic, and mechanical stability. Halogen atoms can effectively tune the electronic structure, dipole moment transition, band alignment, and light absorption. Specifically, ZrX2 monolayers intrinsically exhibit a ferroelasticity with an abnormal 120° orientation rotation, possessing a moderate switching barrier of 24-39 meV/atom. Importantly, we observe superior anisotropic light absorption responses on SL ZrX2 in the visible region. Besides, a series of ZrX2-based excitonic solar cells have been proposed, which hold a large power conversion efficiency limit of 12.4-18.7%.

In this study, sea surface salinity (SSS) indexes are derived from reanalysis and observational datasets to distinguish the two types of (Central Pacific (CP) and Eastern Pacific (EP)) El Nino events in the tropical Pacific. Based on the SSS anomalous spatial and temporal pointwise correlations with sea surface temperature (SST) indexes of two types of El Nino events, the key areas with SSS variations for EP and CP El Nino events are identified. For EP El Nino events, the key areas are located over an arcuate area centered at (0°, 130°E) and in the central equatorial Pacific covering (5°S–5°N, 175°W–158°W). For CP El Nino events, the key areas are located in the northeastern western Pacific covering (2°S–9°N, 142°E–170°E) and in the southeastern Pacific covering (20°S–10°S, 135°W–95°W). The key areas for EP and CP El Nino events in this study are not located near the dateline in the equatorial Pacific and differ from those obtained from the regression or composite methods. Accordingly, these key areas are used to construct SSS indexes, termed as the CP/EP El Nino SSS index (CSI/ESI), to distinguish EP and CP El Nino events independently. The SSS indexes are verified by different datasets over varying time periods and they can be adequately used to identify the two types of El Nino events and serve as another useful tool for monitoring ENSO. These analyses offer novel insight into how to represent the diversity of El Nino events.

Accurately estimating the ocean’s interior structures using sea surface data is of vital importance for understanding the complexities of dynamic ocean processes. In this study, we proposed an advanced machine-learning method, the Light Gradient Boosting Machine (LightGBM)-based Deep Forest (LGB-DF) method, to estimate the ocean subsurface salinity structure (OSSS) in the South China Sea (SCS) by using sea surface data from multiple satellite observations. We selected sea surface salinity (SSS), sea surface temperature (SST), sea surface height (SSH), sea surface wind (SSW, decomposed into eastward wind speed (USSW) and northward wind speed (VSSW) components), and the geographical information (including longitude and latitude) as input data to estimate OSSS in the SCS. Argo data were used to train and validate the LGB-DF model. The model performance was evaluated using root mean square error (RMSE), normalized root mean square error (NRMSE), and determination coefficient (R2). The results showed that the LGB-DF model had a good performance and outperformed the traditional LightGBM model in the estimation of OSSS. The proposed LGB-DF model using sea surface data by SSS/SST/SSH and SSS/SST/SSH/SSW performed less satisfactorily than when considering the contribution of the wind speed and geographical information, indicating that these are important parameters for accurately estimating OSSS. The performance of the LGB-DF model was found to vary with season and water depth. Better estimation accuracy was obtained in winter and autumn, which was due to weaker stratification. This method provided important technical support for estimating the OSSS from satellite-derived sea surface data, which offers a novel insight into oceanic observations.

Bladder cancer (BC) is a familiar malignancy with high morbidity and mortality. The effect of treatment is unsatisfactory after the metastasis and invasion of BC. Hence, more studies should be carried out to explore the metastasis of BC. RT-qPCR or/and western blot was conducted to evaluate miR-494-3p, KLF9, and RGS2 expression. Cell proliferation and invasion were estimated by MTT assay and transwell assay, respectively. Cell migration was tested by wound healing assay and transwell assay. Dual-luciferase reporter gene assay was employed to validate the interplay between miR-494-3p and KLF9 mRNA. The interaction between KLF9 and RGS2 promoter was verified using dual-luciferase reporter gene assay and chromatin immunoprecipitation (ChIP) assay. miR-494-3p expression was upregulated, whereas KLF9 and RGS2 were downregulated in BC cells. miR-494-3p inhibition was competent to limit the growth of BC cells. KLF9 knockdown abolished the miR-494-3p depletion-mediated inhibitory growth of BC cells. Mechanistically, we found that KLF9 was a downstream gene of miR-494-3p and could bind to the promoter region of RGS2 to promote the expression of RGS2. Moreover, RGS2 knockdown abrogated the suppressive effects of miR-494-3p knockdown on the proliferation, migration, and invasion of BC cells. Notably, miR-494-3p inhibition obstructed the tumor growth in nude mice. miR-494-3p silencing inhibited the progression of BC by regulating the KLF9/RGS2 axis in vitro and in vivo, which laid the foundation for experiments of miR-494-3p in BC and provided therapeutic targets for BC.

GM1 ganglioside is particularly abundant in the mammalian central nervous system and has shown beneficial effects on neurodegenerative diseases. In this study, we investigated the therapeutic effect of GM1 ganglioside in experimental models of Parkinson’s disease (PD) in vivo and in vitro. Mice were injected with MPTP (30 mg·kg(-1)·d(−1), i.p.) for 5 days, resulting in a subacute model of PD. PD mice were treated with GM1 ganglioside (25, 50 mg·kg(−)(1)·d(−1), i.p.) for 2 weeks. We showed that GM1 ganglioside administration substantially improved the MPTP-induced behavioral disturbance and increased the levels of dopamine and its metabolites in the striatal tissues. In the MPP(+)-treated SH-SY5Y cells and α-synuclein (α-Syn) A53T-overexpressing PC12 (PC12(α-Syn A53T)) cells, treatment with GM1 ganglioside (40 μM) significantly decreased α-Syn accumulation and alleviated mitochondrial dysfunction and oxidative stress. We further revealed that treatment with GM1 ganglioside promoted autophagy, evidenced by the autophagosomes that appeared in the substantia nigra of PD mice as well as the changes of autophagy-related proteins (LC3-II and p62) in the MPP(+)-treated SH-SY5Y cells. Cotreatment with the autophagy inhibitor 3-MA or bafilomycin A1 abrogated the in vivo and in vitro neuroprotective effects of GM1 ganglioside. Using GM1 ganglioside labeled with FITC fluorescent, we observed apparent colocalization of GM1-FITC and α-Syn as well as GM1-FITC and LC3 in PC12(α-Syn A53T) cells. GM1 ganglioside significantly increased the phosphorylation of autophagy regulatory proteins ATG13 and ULK1 in doxycycline-treated PC12(α-Syn A53T) cells and the MPP(+)-treated SH-SY5Y cells, which was inhibited by 3-MA. Taken together, this study demonstrates that the anti-PD role of GM1 ganglioside resulted from activation of autophagy-dependent α-Syn clearance.

As an inherent property of the device itself, nonlinearity in micro-/nano- electromechanical resonators is difficult to eliminate, and it has shown a wide range of applications in basic research, sensing and other fields. While many application scenarios require tunability of the nonlinearity, inherent nonlinearity of a mechanical resonator is difficult to be changed. Here, we report the experimental observation of a Joule heating induced tuning effect on the nonlinearity of graphene mechanical resonators. We fabricated multiple graphene mechanical resonators and detected their resonant properties by an optical interference method. The mechanical vibration of the resonators will enter from the linear to the nonlinear intervals if we enhance the external driving power to a certain value. We found that at a fixed drive power, the nonlinearity of a mechanical resonator can be tuned by applying a dc bias current on the resonator itself. The tuning mechanism could be explained by the nonlinear amplitude-frequency dependence theory. Our results may provide a research platform for the study of mechanical nonlinearity by using atomic-thin layer materials.

Two-dimensional (2D) antiferromagnetic semiconductor chromium thiophosphate (CrPS4) has gradually become a major candidate material for low-dimensional nanoelectromechanical devices due to its remarkable structural, photoelectric characteristics and potentially magnetic properties. Here, we report the experimental study of a new few-layer CrPS4 nanomechanical resonator demonstrating excellent vibration characteristics through the laser interferometry system, including the uniqueness of resonant mode, the ability to work at the very high frequency, and gate tuning. In addition, we demonstrate that the magnetic phase transition of CrPS4 strips can be effectively detected by temperature-regulated resonant frequencies, which proves the coupling between magnetic phase and mechanical vibration. We believe that our findings will promote the further research and applications of the resonator for 2D magnetic materials in the field of optical/mechanical signal sensing and precision measurement.

The Hilbert transform (HT) is an important method for signal demodulation and instantaneous frequency (IF) estimation. The modulus of the analytic signal constructed by the HT is regarded as the amplitude, and the derivative of the instantaneous phase of the extracted pure frequency modulation signal is the IF. When the spectrums of the amplitude function and the oscillation term overlap so as not to satisfy the Bedrosian condition, the instantaneous amplitude (IA) and frequency calculated by the Hilbert transform will contain errors. The recursive Hilbert transform (RHT) is an effective method to overcome this problem. The RHT regards the pure frequency modulation signal obtained by the previous HT as a new signal and recursively computes its Hilbert transform until convergence. The final pure frequency modulation signal of the recursive procedure has the same zero-crossing points as the original signal, and its corresponding quadrature error signal vanishes. We emphasize the convergence analysis of the algorithm and study the convergent tendency of the quadrature error signal in each recursive step. The key to the proof is that the discrete Fourier transform value of the quadrature error signal is regarded as a vector, and the length/norm of the vector decreases with the recursion process. Finally, three examples are used to demonstrate the effective application of this method in signal demodulation, IF identification and damped vibrating signal analysis, which indicate the application potential of the RHT method in mono-component signal processing.

Quantum storage of 147 temporal modes at telecom-band is experimentally demonstrated by using a fiber-pigtailed laser-written Er3+: LiNbO3 waveguide. Memory efficiency of 2.00±0.09 % is achieved with storage time up to 100 ns.

By pumping a periodically poled lithium niobite waveguide in a Sagnac interferometer, we obtain three types of frequency entangled two-photon states with further spectral manipulation.

Quantum networks play an extremely important role in quantum information science, with application to quantum communication, computation, metrology and fundamental tests. One of the key challenges for implementing a quantum network is to distribute entangled flying qubits to spatially separated nodes, at which quantum interfaces or transducers map the entanglement onto stationary qubits. The stationary qubits at the separated nodes constitute quantum memories realized in matter while the flying qubits constitute quantum channels realized in photons. Dedicated efforts around the world for more than twenty years have resulted in both major theoretical and experimental progress towards entangling quantum nodes and ultimately building a global quantum network. Here, we review the development of quantum networks and the experimental progress over the past two decades leading to the current state of the art for generating entanglement of quantum nodes based on various physical systems such as single atoms, cold atomic ensembles, trapped ions, diamonds with Nitrogen-Vacancy centers, solid-state host doped with rare-earth ions, etc. Along the way we discuss the merits and compare the potential of each of these systems towards realizing a quantum network., Comment: 71 pages, 16 figures, 1 table, accepted by Laser & Photonics Reviews

Recently, the MXene-like MOenes provide a novel combination of mechanical, electronic, and optical properties attractive for next-generation low-dimensional quantum and optoelectronic devices. The Janus structure induced by asymmetric surfaces could bring about unique features due to the existence of a built-in electric field. In this study, Janus 2H- and 1T-Ti2OFCl monolayers are systematically scrutinized via the first-principle calculations. 2H- and 1T-Ti2OFCl monolayers are direct semiconductors with a bandgap of 0.75 and 1.12 eV, respectively. Intriguingly, biaxial strains can lead to a three-component 2D pseudospin-1 fermion and a two-component 2D double Weyl fermion during the quantum phase transitions. The effective k· p models further help to characterize these emergent fermions. In addition, the light absorbance calculations including the excitonic effect show that Ti2OFCl monolayers can be potentially applied in infrared detectors and exciton solar cells. This work would further understand the inherently chemical and physical features of the MOene family.

Bolometers based on graphene have demonstrated outstanding performance with high sensitivity and short response time. In situ adjustment of bolometers is very important in various applications, but it is still difficult to implement in many systems. Here we propose a gate-tunable bolometer based on two strongly coupled graphene nanomechanical resonators. Both resonators are exposed to the same light field, and we can measure the properties of one bolometer by directly tracking the resonance frequency shifts, and indirectly measure the other bolometer through mechanical coupling. We find that the sensitivity and the response bandwidth of both bolometers can be independently adjusted by tuning the corresponding gate voltages. Moreover, the properties of the indirectly measured bolometer show a dependence on the coupling between the two resonators, with other parameters being fixed. Our method has the potential to optimize the design of large-scale bolometer arrays, and open new horizons in infrared/terahertz astronomy and communication systems.

Laser processing plays a key role in treating a lot of materials. The mechanism of laser stealth dicing (SD) is based on irradiation of a laser beam which is focused inside the brittle material. The laser beam scans along the predetermined path, so that the characteristics of the interior brittle material can be changed, the stress layer can be therefore formed. Finally, an external force is applied to separate the brittle material. Since only the limited interior region of a wafer is processed by the laser irradiation, the damages and debris contaminants can be avoided during the SD process. SD has the advantages of a high speed for thinner wafers without any chipping, the smooth section without dust and slag, and completely dry process, which has been widely used in large scale integrated circuits and microelectronic manufacturing systems. However, further studies on the simulation analyze and parameter optimization have kept to be rear for SD so far. In this study, an approach named as constrained interpolation profile (CIP) was adopted, which has the advantages of compactness, stability, and low dissipation in computational fluid dynamics compared with other simulation procedures. We have finished a theoretical simulation to obtain the physical features of the temperature, pressure, density of the silicon substrate at different focal depth where a nanosecond pulsed laser is irradiated, then we found a suitable focal depth with a good dicing quality by analyzing these physical features.

Ocean reanalysis products are used to examine salinity variability and its relationships with temperature in the western equatorial Pacific during 1942-2018. An ensemble empirical mode decomposition (EEMD) method is adopted to separate salinity and temperature signals at different time scales; a focus is placed on interdecadal component in this study. Pronounced interdecadal variations in salinity are seen in the western equatorial Pacific, which exhibits persistent and transitional phases in association with temperature. A surface freshening is accompanied by a surface warming during the 1980s-1990s, but saltening and cooling in the 2000s, with interdecadal shifts occurring around the late 1970s, late 1990s, and in 2016-2018, respectively. Determined by anomaly signs of temperature and salinity, their combined effects can be density-compensated or density-uncompensated, acting to produce density variability that is suppressed or enhanced, respectively. The effects are phase- and region dependent. In the subsurface layers at 200m, where salinity and temperature anomalies are nearly of the same sign during interdecadal evolution, their effects are mostly density-compensated. The situation is more complicated in the surface layer. Variations in SSS and SST during the persistent phases tend to be of opposite sign with their density-uncompensated effects, acting to enhance density anomalies; but they can be of the same sign during the transitional periods, with density-compensated salinity effects. Examples are given for relationships among these fields which exhibit phase differences in anomaly transitions in the late 1990s in the western equatorial Pacific; salinity anomalies are seen to cause a delay in phase transition of density anomalies. Furthermore, their relative contributions to interdecadal variabilities of density and stratification are quantified. The consequences for salinity effects are also discussed with their feedbacks on local SST.

The high-quality 20 mol% Ho3+:BaY2F8 single crystal has been grown by the Czochralski method. The deformation, hardness and Young's modulus of Ho3+:BaY2F8 single crystals have been studied by nanoindentation measuring method. The load-depth of Ho3+:BaY2F8 single crystals were measured under different maximum loads (4–150 mN). The experimental results revealed that the plastic deformation component governs Ho3+:BaY2F8 single crystals at the indentation loads of 4–140 mN. The slip lines in directions appeared at above 30 mN indentation load and increased with indentation load increasing. With the load exceeding 140 mN, a microcrack was detected around the indentation. It is found that materials pile-up and propagation of dislocations dominate the deformation mechanism, where no phase transition occurs. The hardness and Young's modulus are 3.16 ± 0.08 GPa and ~106.9 GPa, respectively. To our best knowledge, the nanoindentation behavior of Ho3+:BaY2F8 single crystal is reported for the first time.

A significant strong, warm “Blob” (a large circular water body with a positive ocean temperature anomaly) appeared in the Northeast Pacific (NEP) in the boreal winter of 2013–2014, which induced many extreme climate events in the US and Canada. In this study, analyses of the temperature and salinity anomaly variations from the Array for Real-time Geostrophic Oceanography (Argo) data provided insights into the formation of the warm “Blob” over the NEP. The early negative salinity anomaly dominantly contributed to the shallower mixed layer depth (MLD) in the NEP during the period of 2012–2013. Then, the shallower mixed layer trapped more heat in the upper water column and resulted in a warmer sea surface temperature (SST), which enhanced the warm “Blob”. The salinity variability contributed to approximately 60% of the shallowing MLD related to the warm “Blob”. The salinity anomaly in the warm “Blob” region resulted from a combination of both local and nonlocal effects. The freshened water at the surface played a local role in the MLD anomaly. Interestingly, the MLD anomaly was more dependent on the local subsurface salinity anomaly in the 100–150 m depth range in the NEP. The salinity anomaly in the 50–100 m depth range may be linked to the anomaly in the 100–150 m depth range by vertical advection or mixing. The salinity anomaly in the 100–150 m depth range resulted from the eastward transportation of a subducted water mass that was freshened west of the dateline, which played a nonlocal role. The results suggest that the early salinity anomaly in the NEP related to the warm “Blob” may be a precursor signal of interannual and interdecadal variabilities.

Ocean chlorophyll (Chl)-induced heating can affect the climate system through the penetration of solar radiation in the upper ocean. Currently, the ocean biology-induced heating (OBH) feedback effects on the climate in the tropical Pacific are still not well understood, and the mechanisms regarding how SST is modulated remain elusive. In this paper, chlorophyll (Chl) data from satellites are combined with physical fields from Argo profiles to estimate OBH-related fields, including the penetration depth (Hp) and the ocean mixed-layer (ML) depth (Hm). In addition, some directly related heating terms with Hm and Hp are diagnosed, including the absorbed solar radiation component within the ML (denoted as Qabs), the rate of ML temperature changes that are directly induced by Qabs (denoted as Rsr = Qabs/(ρ0CpHm)), and the portion of solar radiation that penetrates through the bottom of the ML (denoted as Qpen). The structural relationships between these related fields are examined to illustrate how these heating terms are affected by Hp and Hm. The extent to which Rsr and Qpen are modulated by Hp is strikingly different during ENSO cycles. In the western-central equatorial Pacific, inter-annual variations in Hp tend to be out of phase with those in Hm. A decrease (increase) in Qabs from a positive (negative) Hp anomaly during El Nino (La Nina) tends to be offset by a negative (positive) Hm anomaly. Thus, Rsr is not closely related with Hp, even though Qabs is highly correlated with Hp, indicating that the direct thermal effect through Qabs is not a dominant factor that affects the SST. In contrast, the inter-annual variability of Qpen in the region is significantly enhanced by that of Hp, with their high positive correlation. The Hp-induced differential heating in the ML and subsurface layers from the Qpen and Qabs terms modifies the thermal contrast, stratification and vertical mixing, which represent a dominant indirect ocean dynamical effect on the SST. The revealed relationships between these related fields provide an observational basis for gaining structural insights into the OBH feedback effects and validating model simulations in the tropical Pacific.

AIM: To retrospectively analyze the clinical change of retinal vein occlusion inpatients of the Second People's Hospital of Foshan in the nearby five years.METHODS: The data of inpatients in the Second People's Hospital of Foshan were collected by the term “retinal vein occlusion”from 2013-01-01 to 2017-12-31. Retrospective analysis of the details for the disease.RESULTS: Totally 351 patients with retinal vein occlusion were admitted and treated for 473 times in five years. Elder with systemic disease(hypertension, diabetes and renal inadequacy)was more common. The hospital days were significantly statistical difference among five years with the shortest days in 2017. The prevalence of RVO was growing year by year, especially for BRVO, with statistical difference between 2017 and the other four years(PPCONCLUSION: BRVO is growing more sharply than CRVO in the nearby five years. Retinal laser combined with“1+PRN”intravitreal injection is the main therapeutic regimen for RVO in our hospital.

Hydrogen has promise as a good future alternative to fossil fuels. Electrochemical water splitting is an environmentally friendly way to produce hydrogen, but high overpotentials and cost are the main limitations to the application of electrocatalysts in large-scale hydrogen production. Here, an inexpensive catalyst composed of Ni5P4/NiP2 nanoparticles on Ni5P4/NiP2 nanosheets was prepared by a simple chemical vapor deposition method to increase the active catalytic sites. This nickel phosphide exhibits an overpotential of 35 mV at a current density of 10 mA cm−2 in an acidic condition, outperforming other reported nickel phosphides. Additionally, it shows great stability at a high current density of 1200 mA cm−2, which is very important for large-scale applications. Furthermore, this sample shows pH universality, with good performance in both acidic and alkaline electrolytes. This work advances nickel phosphide as an efficient catalyst for the hydrogen evolution reaction in water splitting.

Recently, two-dimensional (2D) metal halides have brought out an intensive interest for their unique mechanical, electronic, magnetic, and topological properties. Here, we theoretically report the existence of the single-layer (SL) zirconium dihalide materials ZrX

In this paper, we demonstrate the generation of high-performance entangled photon-pairs in different degrees of freedom from a single piece of fiber pigtailed periodically poled LiNbO$_3$ (PPLN) waveguide. We utilize cascaded second-order nonlinear optical processes, i.e. second-harmonic generation (SHG) and spontaneous parametric down conversion (SPDC), to generate photon-pairs. Previously, the performance of the photon pairs is contaminated by Raman noise photons from the fiber pigtails. Here by integrating the PPLN waveguide with noise rejecting filters, we obtain a coincidence-to-accidental ratio (CAR) higher than 52,600 with photon-pair generation and detection rate of 52.3 kHz and 3.5 kHz, respectively. Energy-time, frequency-bin and time-bin entanglement is prepared by coherently superposing correlated two-photon states in these degrees of freedom, respectively. The energy-time entangled two-photon states achieve the maximum value of CHSH-Bell inequality of S=2.708$\pm$0.024 with a two-photon interference visibility of 95.74$\pm$0.86%. The frequency-bin entangled two-photon states achieve fidelity of 97.56$\pm$1.79% with a spatial quantum beating visibility of 96.85$\pm$2.46%. The time-bin entangled two-photon states achieve the maximum value of CHSH-Bell inequality of S=2.595$\pm$0.037 and quantum tomographic fidelity of 89.07$\pm$4.35%. Our results provide a potential candidate for quantum light source in quantum photonics., Comment: 29 pages,7 figures

The time-varying mean (TVM) component plays a vital role in the characterization of non-stationary winds, whereas it is difficult to extract the TVM accurately or to validate it quantitively. To deal with this problem, this paper first develops two additional conditions for the TVM extraction from the perspective of structural wind-induced vibration response, then presents an approach, based on the combination of Vondrak filter and genetic algorithm (Vondrak-G), to derive the optimal TVM from non-stationary wind speed records as well as its turbulence characteristics (i.e. gust factor, turbulence intensity, and turbulence integral length scale). Furthermore, the wind characteristics obtained by the Vondrak-G approach are compared with those by a conventional approach derived for stationary winds, demonstrating that the results by the Vondrak-G approach are evidently more accurate. This paper aims to provide an effective method for accurately extracting the TVM and then evaluating wind characteristics of the non-stationary wind.

Graphene has been considered as one of the best materials to implement mechanical resonators due to their excellent properties such as low mass, high quality factors and tunable resonant frequencies. Here we report the observation of phonon lasing induced by the photonthermal pressure in a few-layer graphene resonator at room temperature, where the graphene resonator and the silicon substrate form an optical cavity. A marked threshold in the oscillation amplitude and a narrowing linewidth of the vibration mode are observed, which confirms a phonon lasing process in the graphene resonator. Our findings will stimulate the studies on phononic phenomena, help to establish new functional devices based on graphene mechanical resonators, and might find potential applications in classical and quantum sensing fields, as well as in information processing.

To realize the near-infrared detection of silicon-based detectors and avoid the incompatibility between III-V photodetectors and silicon-based integrated circuits, the development of Ge/Si detectors has become a research hotspot, with the breakthrough of preparation technology of Ge / Si heterojunction materials. In this paper, the research progress of Ge / Si heterojunction photodetectors in the wavelength range of 1.1μm to 1.6μm is summarized from the aspects of the device structure, working principle, the current situation at home and abroad, the advantages and disadvantages, and so on.

Based on performance improved entangled photon pair source at 1.5 µm, we experimentally demonstrated quantum teleportation with the rate and fidelity of 6.41±0.37 Hz and 87.70±5.75% over a state-transfer distance of 40 km.