Cross-connection of multiplexed cylindrical vector beams using off-axis spin-decoupled metasurfaces.

Cylindrical vector beam (CVB) multiplexing communication demands effective mode cross-connection techniques to establish communication networks. While methods like polarized grating and coordinate transformation have been developed for (de)multiplexing CVB modes, challenges persist in the cross-connection of these multiplexed mode channels, including multi-mode conversion and inhomogeneous polarization control. Herein, we present an independent off-axis spin-orbit interaction strategy utilizing spin-decoupled metasurfaces. Cross-connection is achieved by encoding conjugated Dammann optical vortex grating phases onto the two orthogonal circularly polarized components of CVBs. Experimental results demonstrate the successful interconversion of four CVB modes (CVB+1 and CVB-2, CVB+2 and CVB-4) using a Si-based metasurface with a polarization conversion efficiency exceeding 85%. This facilitates the cross-connection of 200 Gbit/s quadrature phase-shift keying signals with bit-error-rates below 10-6. Offering advantages such as ultra-compact device size, flexible control of CVB modes, and multi-mode parallel processing, this approach shows promise in advancing the networking capabilities of CVB mode multiplexing communication networks.

Grouting Mechanism of Polyurethane Composite Materials in Asphalt Pavement Subsidence.

The mechanical properties of polyurethane grouting materials were significantly improved when cement, sodium meta-silicate, red mud, slag, and fly ash were added. However, the grouting mechanisms of polyurethane composite materials are not clear. The grouting mechanisms of polyurethane composite materials in asphalt pavement subsidence were investigated. The results of computed tomography analysis show that polyurethane foam is filled with geopolymer hydration products. The results from ground penetrating radar after grouting show that mapping has no significant fluctuation or dislocation effect, which indicates that the grouting effect is strong. The high-density electrometer can also test the pavement subsidence place and distribution. The grouting mechanisms indicate that polyurethane foam acts as the consolidation structure, and the geopolymer filled with the foam pores of polyurethane and geopolymer forms a stable consolidated body. The seriflux includes under-layer seriflux (red mud, slag, water, and polyurethane composite materials) and upper-layer seriflux (polyurethane seriflux), and there exists a weak phase separation phenomenon, in which the separation phase is mainly polyurethane with little red mud-based geopolymer.

Ultrawide and unidirectional enhancements of a photonic spin Hall effect in a tilted uniaxial crystal.

Since the enhancement of the photonic spin Hall effect (PSHE) is limited around the Brewster's angle, the scientific problem of how to extend the range of incident angles and to keep them unidirectional for the enhanced PSHE remains open. Here, we propose an effective method to achieve the ultrawide angle and unidirectional enhancement of PSHE via the omnidirectional Brewster's effect in a tilted uniaxial crystal. By properly setting the permittivity and the optical axial angle of the uniaxial crystal, the omnidirectional Brewster's effect can be obtained to realize an ultrawide angle enhancement of the PSHE. Then, by appropriately deviating the optical axial angle, the ultrawide enhancement of the PSHE can be achieved within the maximum incident angle range of 60° with unchanged direction. These findings inspire an unprecedented route to facilitate the applications in precision measurement and spin-dependent devices.

Effect of a Simulated Coal Mine Environment on Polyurethane Grouting Material and a Proposed Polyurethane Strengthening Method.

When it comes to grouting in coal mines, polyurethane (PU) is often utilized. However, it is of vital importance to consistently improve the mineral PU, considering the significant amount of environmental deterioration to which it is prone. Laboratory experiments were used to model various coal mine conditions. Additionally, a workable technique for PU strengthening using ultrasonic waves was proposed. Compression tests and scanning electron microscopy (SEM) were used to describe the PU-gangue material's induration characteristics. The results showed that ultrasound has a positive impact on PU's mechanical strength. The final strength of the PU was significantly impacted by the size of the coal gangue particles, the amount of dust, and the amount of water. The induration made of gangue and PU with the same mass but differing particle sizes was noticeably different in its compressive strength. The strengthening mechanism showed that the average size of the rigid foam after the ultrasound treatment was smaller, and the 'honeycomb'-structured space in the inner section was more compact, resulting in the rigid PU foam having a higher compressive strength after ultrasound treatment. Furthermore, the dust content and water content of coal mines need to be controlled within a specific range to ensure the effective use of PU grouting materials.

Synthesis of Porous Materials Using Magnesium Slag and Their Adsorption Performance for Lead Ions in Aqueous Solution.

Magnesium slag-based porous materials (MSBPM) were successfully synthesized using alkali activation and foaming methods as an effective adsorbent for Pb2+ in solution. The effects of foaming agent type, foaming agent dosage, alkali dosage, and water glass modulus on the properties of the MSBPM were studied, and the micromorphology and porosity of the MSBPM were observed using microscopy. The influence of pH value, initial concentration, and adsorbent dosage on the Pb2+ adsorption was investigated. The results showed that a porous material (MSBPM-H2O2) with high compressive strength (8.46 MPa) and excellent Pb2+ adsorption capacity (396.11 mg·g-1) was obtained under the optimal conditions: a H2O2 dosage of 3%, an alkali dosage of 9%, a water glass modulus of 1.3, and a liquid-solid ratio of 0.5. Another porous material (MSBPM-Al) with a compressive strength of 5.27 MPa and the Pb2+ adsorption capacity of 424.89 mg·g-1 was obtained under the optimal conditions: an aluminum powder dosage of 1.5‱, an alkali dosage of 8%, a water glass modulus of 1.0, and a liquid-solid ratio of 0.5. When the pH of the aqueous solution is 6 and the initial Pb2+ concentrations are 200~500 mg·L-1, the MSBPM-H2O2 and MSBPM-Al can remove more than 99% of Pb2+ in the solution. The adsorption process of both materials followed the Langmuir isotherm model and pseudo-second-order kinetic model, indicating that the adsorption process was a single-molecule layer chemical adsorption.

Thickness-dependent in-plane shift of photonic spin Hall effect in an anisotropic medium.

As the in-plane spin splitting (IPSS) has a broad application for the precision measurement and sensing, it is extremely important to explore its enhancement mechanism via the photonic spin Hall effect (PSHE). However, for a multilayer structure, the thickness in most of previous works is generally set as a fixed value, lacking the deeply exploration of the influence of thickness on the IPSS. By contrast, here we demonstrate the comprehensive understanding of thickness-dependent IPSS in a three layered anisotropic structure. As thickness increases, near the Brewster angle, the enhanced in-plane shift exhibits a thickness-dependently periodical modulation, besides with much wider incident angle than that in an isotropic medium. While near the critical angle, it becomes thickness-dependently periodical or linear modulation under different dielectric tensors of the anisotropic medium, no longer keeps almost constant in an isotropic medium. In addition, as exploring the asymmetric in-plane shift with arbitrary linear polarization incidence, the anisotropic medium could bring more obvious and wider range of thickness-dependently periodical asymmetric splitting. Our results deepen the understanding of enhanced IPSS, which is expected to promise a pathway in an anisotropic medium for the spin control and integrated device based on PSHE.

Generalized Brewster angle-enhanced photonic spin Hall effect in an all-dielectric metasurface.

The enhancement of the photonic spin Hall effect (PSHE) is usually limited at horizontally polarized incidence and around the nonadjustable Brewster angle. In this Letter, a flexible method for enhancing the reflective PSHE with tunable incident angle under both vertically (V) and horizontally (H) polarized light has been theoretically explored. By using the multipole decomposition method, the variable generalized Brewster angle (GBA) is proven to be obtained under both V- and H-polarized light at different wavelengths in the all-dielectric metasurface. Then, owing to the large ratio of Fresnel coefficients at the GBA, the enhancement of PSHE in this Letter can not only be available for both V- and H-polarization, but also achieved at widely tunable incident angle and different operating wavelengths in the same metasurface. This work provides a simple method to achieve the flexible enhancement of PSHE and offers a novel way for designing a functional spin-based photonic device.

Occurrence of halogenated methanesulfonic acids in water and sediment from the Hangzhou Bay, China.

Halogenated methanesulfonic acids (HMSAs) are an important new class of organic compounds as they were universal in the water cycle and drinking water sources. However, no study has investigated the presence of HMSAs in surface water and sediment from China. The present study reports the occurrence and spatiotemporal distribution of seven HMSAs in water and sediment samples from Hangzhou Bay, China. Trifluoromethanesulfonic acid (TFMSA) was the main contributor to the concentrations of HMSAs in water and sediment samples from spring, summer, autumn and winter which were 30.8-541 ng/L, n. d.-86.6 ng/L, 4.22-70.9 ng/L and 8.86-192 ng/L, separately, while in sediment samples were n. d.-11.1 ng/g, n. d.-12.9 ng/g, n. d.-22.5 ng/g, n. d.-4.60 ng/g, respectively. The levels of HMSAs in water from winter and spring were higher than those in summer and autumn, and the concentrations of the target HMSAs in water presents a seasonal pattern affected by the temperature, the precipitation and river flow variations. Nevertheless, the levels of HMSAs in sediment were highest in the area near the industrial area and the confluences of rivers. Correlation analysis revealed that the concentrations of TFMSA were significantly positively correlated with total organic carbon (TOC) in water samples. Although TFMSA is regarded as low toxic based on the EC50 value of acute toxicity, the potential risks to aquatic ecology should be paid more attention due to its high concentrations in the aquatic system and the environmental persistency.

Quadratic spin Hall effect of light due to phase change.

The spin Hall effect (SHE) of light has brought important applications, but the involved spin states only split in one direction. Here we employ an accurate three-dimensional model of light to show that the SHE generally exhibits quadratic spin splitting, i.e., both vertical and horizontal splitting, in the presence of a fast phase change of reflection. Further, we disclose that the two splittings are actually different from each other, and that they originate from the vertical and horizontal spin momentum flows, respectively, owing to the spatial gradient of polarization in the individual direction. Finally, it is found that by tuning the incident angle and polarization of light, one can manipulate the quadratic SHE so as to realize a variety of spin splittings, such as unbalanced quadratic splitting and off-center splitting of spin states.

Multiple Functions of MiRNAs in Brassica napus L.

The worldwide climate changes every year due to global warming, waterlogging, drought, salinity, pests, and pathogens, impeding crop productivity. Brassica napus is one of the most important oil crops in the world, and rapeseed oil is considered one of the most health-beneficial edible vegetable oils. Recently, miRNAs have been found and confirmed to control the expression of targets under disruptive environmental conditions. The mechanism is through the formation of the silencing complex that mediates post-transcriptional gene silencing, which pairs the target mRNA and target cleavage and/or translation inhibition. However, the functional role of miRNAs and targets in B. napus is still not clarified. This review focuses on the current knowledge of miRNAs concerning development regulation and biotic and abiotic stress responses in B. napus. Moreover, more strategies for miRNA manipulation in plants are discussed, along with future perspectives, and the enormous amount of transcriptome data available provides cues for miRNA functions in B. napus. Finally, the construction of the miRNA regulatory network can lead to the significant development of climate change-tolerant B. napus through miRNA manipulation.

Wide-range electrically tunable photonic spin Hall effect in a quasi-PT-symmetric structure.

The photonic spin Hall effect (PSHE), manifesting itself as the spin-dependent shifts of left- and right-handed circularly polarized light beams, holds potential applications in nanophotonics and precision measurement. Thus, realizing effective enhancement and regulation of PSHE is highly desirable. It is known that by adjusting the Fermi energy of graphene, the spin shifts in a graphene-based optical structure can be actively modulated and amplified. However, this method generally works in a very narrow range of incident angles (near Brewster's angle) and the incident state is limited to the horizontal polarization. In this Letter, we address these issues by theoretically proposing a feasible way to amplify and control the PSHE in a wide range of incident angles by modulating the Fermi energy when the light beam is reflected at a quasi-PT-symmetric structure (gain-loss medium embedded with monolayer graphene). Interestingly, we reveal that the electrically tunable PSHE can be achieved for both horizontal and vertical polarizations near the quasi-exceptional points (quasi-EPs). Moreover, we can directly determine the tiny variation of the Fermi energy by observing the field distribution of a single circularly polarized component in this structure without using the weak measurements.

Role of in-plane shift in reconstructing the photonic spin Hall effect.

The photonic spin Hall effect (SHE) manifests itself as in-plane and transverse spin-dependent shifts of left- and right-handed circularly polarized (LCP, RCP) components and originates from the spin-orbit interaction (SOI) of light, where extrinsic orbital angular momentum (EOAM) can induce these shifts. However, previous studies mainly focus on the SOI corresponding to transverse shifts and generally consider the paraxial approximation case. In this Letter, we reconstruct a more general theory of the photonic SHE in the non-paraxial case and reveal that the induction of an in-plane shift mainly relies on the EOAM of the y direction, supplemented by the EOAM of the x and z directions under the laboratory coordinate system. In addition, the EOAM in the x and z directions completely determine the transverse shift. Moreover, the angular momentum conversion between the LCP and RCP components results in the angular momentum of the LCP (RCP) component of the incident Gaussian beam not being equal to the sum of the angular momentum of the LCP (RCP) component of the reflected and transmitted light. These findings explore the influence of in-plane shifts on the SOI of light and provide an in-depth understanding of the photonic SHE.

Research on remote sensing classification of fruit trees based on Sentinel-2 multi-temporal imageries.

Accurately obtaining the spatial distribution information of fruit tree planting is of great significance to the development of fruit tree growth monitoring, disease and pest control, and yield estimation. In this study, the Sentenel-2 multispectral remote sensing imageries of different months during the growth period of the fruit trees were used as the data source, and single month vegetation indices, accumulated monthly vegetation indices (∑VIs), and difference vegetation indices between adjacent months (∆VIs) were constructed as input variables. Four conventional vegetation indices of NDVI, PSRI, GNDVI, and RVI and four improved vegetation indices of NDVIre1, NDVIre2, NDVIre3, and NDVIre4 based on the red-edge band were selected to construct a decision tree classification model combined with machine learning technology. Through the analysis of vegetation indices under different treatments and different months, combined with the attribute of Feature_importances_, the vegetation indices of different periods with high contribution were selected as input features, and the Max_depth values of the decision tree model were determined by the hyperparameter learning curve. The results have shown that when the Max_depth value of the decision tree model of the vegetation indices under the three treatments was 6, 8, and 8, the model classification was the best. The accuracy of the three vegetation index processing models on the training set were 0.8936, 0.9153, and 0.8887, and the accuracy on the test set were 0.8355, 0.7611, and 0.7940, respectively. This method could be applied to remote sensing classification of fruit trees in a large area, and could provide effective technical means for monitoring fruit tree planting areas with medium and high resolution remote sensing imageries.

Transformation from asymmetric spin splitting to symmetric spin splitting with phase compensation in photonic spin Hall effect.

Generally, when an arbitrary polarized light beam is reflected or refracted from an isotropic interface, the spin splitting in photonic spin Hall effect (SHE) shows asymmetry properties. In this paper, we theoretically propose a phase compensation scheme to achieve the transformation from asymmetric spin splitting to symmetric spin splitting in photonic SHE. We experimentally acquire the spin splitting after phase compensation in the case of a 45 degrees linear polarized Gaussian light beam totally internally reflected from a prism-air interface. Particularly, whether or not phase compensation, the transverse shift of total barycenter of reflected field [i.e., the Imbert-Fedorov (IF) shift] does not change. These findings can solve this problem that asymmetric spin splitting cannot be observed by weak measurements.

Effects of hydration parameters on chemical properties of biocrudes based on machine learning and experiments.

To investigate the effects of temperature and biomass concentration of Hydrothermal liquefaction (HTL) on chemical properties of biocrudes, machine learning (ML) was used to predict the weight of hydration parameters on the properties of biocrudes. The elemental compositions, molecular weights, functional groups, thermal degradation, molecular structure of biocrudes were studied. The optimum yield of biocrudes was 65% and the highest heat value reached up to 34.28 kJ/g, showing comparable fuel properties. It was found that the hydration temperature significantly affects the elemental components, functional groups and molecular weight and structures of biocrudes. In addition, biomass concentration also affect the functional groups and structures of biocrudes. ML results indicated that Support Vector Machine Linear Kernel method is suitable for heat value prediction.

Optimal weak measurement in the photonic spin Hall effect for arbitrary linear polarization incidence.

The photonic spin Hall effect (SHE) has great potential in precision metrology due to its unique spin modulation characteristics. To improve its potential, the effective enhancement of detection precision has become an important issue. In this work, we theoretically and experimentally demonstrate the optimal weak measurement (optimal overlap of pre-selected and post-selected states) with arbitrary linear polarization incidence for both amplified transverse and in-plane shift. Also, based on photonic SHE, a method for arbitrary linear polarization angle detection is then proposed experimentally with a detection accuracy of 0.04 degree. It can provide a guidance for the weak measurement and enlarge the potential application of photonic SHE in field of precision measurement.

Adsorption mechanism of polycyclic aromatic hydrocarbons using wood waste-derived biochar.

The polycyclic aromatic hydrocarbons (PAHs) have been attracted increasing attentions due to their carcinogenicity and teratogenicity. Adsorption is widely considered one of the most potential technologies for PAHs removal. In this study, we prepared two kinds of oxygen-rich biochar derived from waste wood to investigate the PAHs adsorption performance, and the molecular simulation was used to build the 16 priority PAHs, 23 nitrated PAHs, 9 oxygenated PAHs adsorption model. The surface adsorption performance of oxygen-rich biochar significantly depends on the pyrolysis conditions. The main out-comings demonstrated that the adsorption of naphthalene (C10H8) molecules first occurred, and the optimal adsorption positions of oxygen-rich biochar strongly adhered to functional groups of carboxyl and hydroxyl. Moreover, benzene ring, -COOH, and -CH3 of biochar were the main adsorbed functional groups for PAHs adsorption. The oxygen-rich biochar had the targeted-adsorption effect on PAHs removal especially symmetrical PAHs, and the targeted-adsorption mechanism was finally proposed. The research is beneficial to guide the removal of PAHs from polluted water and mitigate the environmental pollution caused by biomass waste mismanagement, simultaneously.

Influence of catalyst and solvent on the hydrothermal liquefaction of woody biomass.

Hydrothermal liquefaction of woody biomass with catalysts was commonly applied in bio-energy research, but the effects of catalyst and solvent on yield and properties of bio-energy are not clear. In this work, the influences of catalyst and solvent on bio-energy production were studied, during which four solvents and three catalysts were used, and the liquefaction parameters were optimized by experimental and Machine learning (ML) method. Results show that the maximum yields of bio-oil and biochar are 65.0% and 32.0%, respectively, and the caloricvalues of bio-oil and biochar are 31.2 MJ/kg and 26.5 MJ/kg, respectively. Alkaline catalysts and 1,4-butanediol-triethanolamine mix solvent can benefit the bio-energy generation. In addition, a Random Forest (RF) was developed to forecast the yields, and the method performed well with experimental results.

Characterizing the Diffusion and Rheological Properties of Aged Asphalt Binder Rejuvenated with Bio-Oil Based on Molecular Dynamic Simulations and Laboratory Experimentations.

Soybean-derived bio-oil is one of the vegetable-based oils that is gaining the most interest for potential use in the rejuvenation of aged asphalt binders. This laboratory study was conducted to characterize and quantify the diffusion and rheological properties of bio-oil-rejuvenated aged asphalt binder (BRAA) using soybean oil. In the study, the chemical structure of the soybean oil was comparatively characterized using an element analyzer (EA), gel permeation chromatography (GPC), and a Fourier infrared (FTIR) spectrometer, respectively. Based on the chemical structure of the bio-oil, BRAA molecular models were built for computing the diffusion parameters using molecular dynamic simulations. Likewise, a dynamic shear rheometer (DSR) test device was used for measuring and quantifying the rheological properties of the aged asphalt binder rejuvenated with 0%, 1%, 2%, 3%, 4%, and 5% soybean oil, respectively. The laboratory test results indicate that bio-oil could potentially improve the diffusion coefficients and phase angle of the aged asphalt binder. Similarly, the corresponding decrease in the complex shear modulus has a positive effect on the low-temperature properties of BRAA. For a bio-oil dosage 4.0%, the diffusion coefficients of the BRAA components are 1.52 × 10-8, 1.33 × 10-8, 3.47 × 10-8, 4.82 × 10-8 and 3.92 × 10-8, respectively. Similarly, the corresponding reduction in the complex shear modulus from 1.27 × 107 Pa to 4.0 × 105 Pa suggests an improvement in the low-temperature properties of BRAA. Overall, the study contributes to the literature on the potential use of soybean-derived bio-oil as a rejuvenator of aged asphalt binders.

Enhanced photonic spin Hall effect via singularity induced by destructive interference.

In this work, we report a simple and effective method for enhancing the photonic spin Hall effect (SHE) via singularity induced by destructive interference in an ultrathin uniaxial slab. Deriving from anisotropy, the incident angles corresponding to destructive interference for p- and s-polarized waves will be deviated, leading to an enhancement peak in transverse spin shift. Interestingly, by adjusting the thickness of slab, the destructive interference and the Brewster effect can act together. At this point, the photonic SHE exhibits great singularity, and the maximum transverse spin shift can approach about three times more than that of the Brewster effect acting alone. This Letter reveals the influence of the interference effect on photonic SHE in layered media and provides a simple way to achieve enhanced photonic SHE.