Search

The algorithm proposed in this paper aims at solving the problem of star map matching in high-limiting-magnitude astronomical images, which is inspired by geometric voting star identification techniques. It is a two-step star map matching algorithm relying only on angular features, and adopts a reasonable matching strategy to overcome the problem of poor real-time performance of the geometric voting algorithm when the number of stars is large. The algorithm focuses on application scenarios where there are a large number of dense stars (limiting magnitude greater than 13, average number of stars per square degree greater than 185) in the image, which is different from the sparse star identification problem of the star tracker, which is more challenging for the robustness and real-time performance of the algorithm. The proposed algorithm can be adapted to application scenarios such as unreliable brightness information, centroid positioning error, visual axis pointing deviation, and a large number of false stars, with high accuracy, robustness, and good real-time performance. [ABSTRACT FROM AUTHOR]

Electrocatalytic nitrite (NO2−) reduction reaction (NO2−RR) for ammonia (NH3) synthesis is a promising alternative for NO2− resource utilization. Herein, a dual‐site copper‐cobalt oxide catalyst is reported for the efficient electrocatalytic reduction of NO2− to NH3, exhibiting NH3 Faradaic efficiency that remained above 95% (0.1 m NaNO2) over a wide potential window (−0.1 to −0.6 V vs reversible hydrogen electrode, vs RHE). More importantly, the high NH3 Faradaic efficiency maintains an over 85% (−0.1 to −0.3 V vs RHE) at a low concentration of NaNO2 (0.01 m). Theoretical calculations demonstrate that CuO serves the *NO2 to *NO and is subsequently converted to NH3 on Co3O4. Coupled anodic ethylene glycol (EG) oxidation reaction endows low cell voltage (ΔU = 480 mV, 10 mA cm−2) and energy consumption saving (>23%) in a two‐electrode system. This work provides a reference for a co‐upcycling electrolyzer for NO2− and EG. [ABSTRACT FROM AUTHOR]

The monitoring of space debris is important for spacecraft such as satellites operating in orbit, but the background in star images taken by ground-based telescopes is relatively complex, including stray light caused by diffuse reflections from celestial bodies such as the Earth or Moon, interference from clouds in the atmosphere, etc. This has a serious impact on the monitoring of dim and small space debris targets. In order to solve the interference problem posed by a complex background, and improve the signal-to-noise ratio between the target and the background, in this paper, we propose a novel star image enhancement algorithm, MBS-Net, based on background suppression. Specifically, the network contains three parts, namely the background information estimation stage, multi-level U-Net cascade module, and recursive feature fusion stage. In addition, we propose a new multi-scale convolutional block, which can laterally fuse multi-scale perceptual field information, which has fewer parameters and fitting capability compared to ordinary convolution. For training, we combine simulation and real data, and use parameters obtained on the simulation data as pre-training parameters by way of parameter migration. Experiments show that the algorithm proposed in this paper achieves competitive performance in all evaluation metrics on multiple real ground-based datasets. [ABSTRACT FROM AUTHOR]

Space debris detection is vital to space missions and space situation awareness. Convolutional neural networks are introduced to detect space debris due to their excellent performance. However, noisy labels, caused by false alarms, exist in space debris detection, and cause ambiguous targets for the training of networks, leading to networks overfitting the noisy labels and losing the ability to detect space debris. To remedy this challenge, we introduce label-noise learning to space debris detection and propose a novel label-noise learning paradigm, termed Co-correcting, to overcome the effects of noisy labels. Co-correcting comprises two identical networks, and the predictions of these networks serve as auxiliary supervised information to mutually correct the noisy labels of their peer networks. In this manner, the effect of noisy labels can be mitigated by the mutual rectification of the two networks. Empirical experiments show that Co-correcting outperforms other state-of-the-art methods of label-noise learning, such as Co-teaching and JoCoR, in space debris detection. Even with a high label noise rate, the network trained via Co-correcting can detect space debris with high detection probability. [ABSTRACT FROM AUTHOR]

Most background suppression algorithms are weakly robust due to the complexity and fluctuation of the star image's background. In this paper, a background suppression algorithm for stray lights in star images is proposed, which is named BSC-Net (Background Suppression Convolutional Network) and consist of two parts: "Background Suppression Part" and "Foreground Retention Part". The former part achieves background suppression by extracting features from various receptive fields, while the latter part achieves foreground retention by merging multi-scale features. Through this two-part design, BSC-Net can compensate for blurring and distortion of the foreground caused by background suppression, which is not achievable in other methods. At the same time, a blended loss function of smooth_L1&Structure Similarity Index Measure (SSIM) is introduced to hasten the network convergence and avoid image distortion. Based on the BSC-Net and the loss function, a dataset consisting of real images will be used for training and testing. Finally, experiments show that BSC-Net achieves the best results and the largest Signal-to-Noise Ratio (SNR) improvement in different backgrounds, which is fast, practical and efficient, and can tackle the shortcomings of existing methods. [ABSTRACT FROM AUTHOR]

Abstract Phenol is a typical aromatic organic byproduct in the coking industry, which can be also as a raw material for producing some useful chemicals by catalytic hydrogenation. In this paper, by constructing carbon/ZrO 2 porous support with abundant vacancies for loading nickel and cobalt nanoparticles (i.e., Ni x Co y @C/ZrO 2) with using Zr-based metal organic frameworks as the precursor, the significant phenol converting enhancement in both hydrothermalcatalytic activity and stability has been fulfilled. Specially, the physiochemical characteristics of the Ni x Co y @C/ZrO 2 particles have been analyzed, which verified the presence of Ni Co alloy and its high homogeneity and dispersity. The catalytic results showed that the Ni 3 Co 1 @C/ZrO 2 catalyst has the best catalytic performance at the desired temperature of 200 °C for 240 min, and the conversion of phenol is 96.33% while the selectivity of cyclohexanol is 91.14%. Kinetic study showed that the activation energy was only 44.31 kJ/mol, which reflected that the hydrogenation could be easily carried out with Ni 3 Co 1 @C/ZrO 2 catalyst. These findings can provide a good guidance for designing and developing the non-noble-metal catalysts for achieving the industrial utilization of phenol in coking wastewater in the future. Graphical abstract Image 1061 Highlights • Phenol is a typical aromatic organic byproduct of the coking industries. • The Ni 3 Co 1 @C/ZrO 2 catalyst has been prepared. • Phenol can be easily converted into cyclohexanol with Ni 3 Co 1 @C/ZrO 2 catalyst. • The Ni Co alloy and its dispersity play an important role on the selective catalysis. [ABSTRACT FROM AUTHOR]

This report puts forward an economically-feasible method for the preparation of a novel lithium doped metal–organic framework (i.e., Li/UiO-66). UiO-66 was impregnated with an ethanol solution of lithium nitrate instead of expensive and toxic organolithium. Lithium nitrate was used as the alkali-metal resource for the modified MOFs. The samples were characterized by XRD, FTIR, XPS, BET, etc. The results indicated that free carboxylate protons can be replaced by the doped lithium cations and the formed lithium carboxylate groups. The effect of the doped lithium on CO2 adsorption and separation was evaluated by gas sorption isotherm measurements. Moreover, the interaction between adsorbed CO2 and the MOFs was studied by in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS). The in situ DRIFTS results showed that the doped lithium can increase the concentration of the active metal sites, which can provide some new adsorption sites for CO2. [ABSTRACT FROM AUTHOR]

The metal‐organic framework HKUST‐1 was modified by lithium doping to enhance its CO2 adsorption property. An optimal CO2 adsorption capacity was achieved as a lithium nitrate solution with a moderate concentration was used as the doping agent in the modified HKUST‐1. The chemical and crystalline structures of the modified HKUST‐1 were characterized in detail. It was found that the crystalline structures and morphologies of HKUST‐1 were well preserved after lithium doping. Also, the lithium doping did not deteriorate the thermal stability of HKUST‐1. Based on the experimental results of CO2 adsorption by in‐situ diffuse reflectance infrared Fourier transform spectroscopy, a possible mechanism of CO2 adsorption in the lithium doped HKUST‐1 was proposed. It is believed that the incorporation of lithium has enhanced the interaction between CO2 molecules and the metal‐organic frameworks. As a result, the CO2 adsorption capacity greatly increased. These findings and insights are helpful to the development of high‐performance materials for CO2 adsorption in the future. The metal‐organic framework HKUST‐1 was synthesized and modified by lithium doping to enhance its CO2 adsorption property. And then the adsorption mechanism of carbon dioxide (CO2) on xLi/HKUST‐1 was studied by in‐situ diffuse reflectance infrared Fourier transform spectroscopy. [ABSTRACT FROM AUTHOR]

To prevent global warming caused by the burning of fossil fuels, the formation of metal organic framework materials (i.e., MOFs) is a promising approach for efficient and scalable CO2 adsorption from air. In this study, a novel stable layered bis-phosphonate MOF, i.e., MIL-91(Al), has been synthesized for adsorption of CO2 under ambient conditions. XRD, N2 adsorption–desorption isotherms, FTIR and HRTEM were employed to characterize the synthesized MIL-91(Al). The results show that MIL-91(Al) demonstrates an excellent adsorption performance for CO2 (i.e., the maximum adsorption can reach up to 2.4 mmol g−1) and a relatively high selectivity for CO2vs. other gases (e.g., N2 or CH4). Moreover, the adsorption behavior of CO2 onto the surface of MIL-91(Al) has also been investigated using in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS). The DRIFTS results show that CO2 can be adsorbed by both the free polar groups (N…H–OP) and the Al–OH–Al bond. The special adsorption behavior is caused by the layered structure of MIL-91(Al) which leads to the exposure of Al on the surface. [ABSTRACT FROM AUTHOR]

Star image registration is the most important step in the application of astronomical image differencing, stacking, and mosaicking, which requires high robustness, accuracy, and real-time capability on the part of the algorithm. At present, there are no high-performance registration algorithms available in this field. In the present paper, we propose a star image registration algorithm that relies only on radial module features (RMF) and rotation angle features (RAF) while providing excellent robustness, high accuracy, and good real-time performance. The test results on a large amount of simulated and real data show that the comprehensive performance of the proposed algorithm is significantly better than the four classical baseline algorithms as judged by the presence of rotation, insufficient overlapping area, false stars, position deviation, magnitude deviation, and complex sky background, making it a more ideal star image registration algorithm than current alternatives. [ABSTRACT FROM AUTHOR]

Electrocatalytic nitrate (NO 3 −) reduction reaction (NO 3 −RR) is a promising avenue for wastewater treatment and value-added ammonia (NH 3) generation. Herein, cobalt manganese spinel nanoparticles embedded in multichannel carbon fibers (CoMn 2 O 4 /NC) to obtain optimal NH 3 Faradaic efficiency is 92.4% with a yield rate of 144.5 mmol h−1 g−1 at − 0.7 V versus reversible hydrogen electrode (vs. RHE). The interfacial between CoMn 2 O 4 and NC induces the 3d orbital electrons of Co and Mn in less localized states, which promotes *NH 3 desorption. Electrochemical in situ Raman spectra and online differential electrochemical mass spectrometry (DEMS) identified the intermediates and products. The theoretical calculation demonstrates that the existence of NC could reduce the free energy difference of the rate-determining step (RDS, 0.42 eV) of NO 3 −RR, suppressing hydrogen evolution reaction (HER) by enhancing the interaction of *H. Coupled benzyl alcohol oxidation reaction (BOR) with NO 2 −RR to obtain lower reduction voltage and high value-added anode products. [Display omitted] • Carbon species induce electronic delocalization of CoMn 2 O 4 to facilitate NO x − to NH 3. • CoMn 2 O 4 /NC exhibits the optimal NH 3 Faradaic efficiency is 92.4% at − 0.7 V vs. RHE. • CoMn 2 O 4 /NC can promote the NO 3 −RR with a lower free energy difference of RDS. • CoMn 2 O 4 /NC can effectively suppress HER by enhancing the interaction of *H. • NO 2 −RR||BOR can enhance energy efficiency and obtain a high-value-added product. [ABSTRACT FROM AUTHOR]

The introduce sulfur species by filling oxygen vacancies to tailor the electronic structure of Co 3 O 4 nanosheets for enhancing the performance of electrocatalytic nitrogen oxyanions reduction to ammonia at ambient conditions. The two-electrode extended system confirms that the catalyst can produce ammonia and high value-added benzoic acid simultaneously. [Display omitted] • Sulphur fills oxygen vacancies to tailor the electronic structure of the Co 3 O 4. • Sulfur species and oxygen vacancies synergy boosted electroreduction NO x − to ammonia. • Electrochemical in situ Raman confirmed S5-Co 3 O 4 exhibits excellent stability. • Coupling of BOR can obtain benzoic acid while efficiently producing ammonia. Electrocatalytic reduction of nitrogen oxyanions (NO x −, x = 3 and 2) to ammonia (NH 3) under ambient conditions is an alternative to the Haber-Bosch process (HBP). Recent catalysts are vulnerable to low-rate and -selectivity NH 3 synthesis due to the multi-step electron–proton transfer process and water as a proton donor, especially in neutral media. Herein, we introduce sulfur species into Co 3 O 4 spinel nanosheets (S-Co 3 O 4) inspired by the bio-nitrogenase of metal-sulfur clusters to alleviate the above dilemma. The S5-Co 3 O 4 exhibits an NH 3 yield rate of 174.2 mmol h−1 g−1 at − 0.6 V versus reversible hydrogen electrode (RHE) with a Faradaic efficiency of 89.9 %, nitrate (NO 3 −) as feedstock. Furthermore, nitrite (NO 2 −) reduction possesses comparable NH 3 Faradaic efficiency (87.6 %) and a higher yield rate (314.5 mmol h−1 g−1) at the same conditions. Theoretical calculations demonstrated that sulfur species reduce the free energy change of formation *H, boosting the activation of *NO x (x = 3 and 2). A two-electrode device, S5-Co 3 O 4 as bifunctional catalysts, demonstrates excellent NH 3 Faradaic efficiency (>95 %) over a wide voltage range for NO 2 −RR, while the anode produces high value-added benzoic acid. [ABSTRACT FROM AUTHOR]

• The CuCo 2 O 4 /CFs was prepared by electrospun for electrocatalytic NO 3 − to NH 3. • The NH 3 Faradaic efficiency of CuCo 2 O 4 /CFs was 81.9 % at − 0.3 V vs RHE. • Coupling of MOR can reduce the cell voltage of 360 mV at 10 mA cm−2. Electrocatalytic reduction of nitrate (NO 3 −, NO 3 RR) provides an effective strategy to mitigate water pollution of human-caused but obtain high-value ammonia (NH 3) under environmental conditions based on renewable energy. In this study, we prepared porous carbon nanofibers (CFs)-supported CuCo 2 O 4 composite (CuCo 2 O 4 /CFs) electrocatalyst by electrospun-pyrolysis method for efficient conversion of NO 3 − to NH 3. The experimental results revealed that the CFs could contribute to charge transfer and inhibit the hydrogen evolution reaction (HER), which preferentially catalyzes NO 3 −-to-NO 2 −. On the other hand, internally confined CuCo 2 O 4 nanoparticles conduce to stabilize adsorbed nitrite intermediate (*NO 2) for further conversion to NH 3. The CuCo 2 O 4 /CFs exhibit the maximum NH 3 Faradaic efficiency of 81.9 % at − 0.3 V versus reversible hydrogen electrode (vs RHE) with a yield rate of 394.5 mmol h−1 g−1 at ambient conditions. The theoretical analysis demonstrated that the *NH 3 desorption is a potential rate-determining step (RDS) with an uphill energy change of 0.76 eV over CuCo 2 O 4. Furthermore, CuCo 2 O 4 /CFs as difunctional catalysts, coupling NO 3 − reduction with methanol oxidation (NO 3 RR||MOR) to substitute water splitting simultaneously at a low voltage. This work provides a strategy for combining NH 3 electrosynthesis with methanol oxidation to high value-added chemicals under ambient conditions. [ABSTRACT FROM AUTHOR]

Soil plays a fundamental role in food safety and the adverse effects of contaminants like heavy metal (loid)s on crop quality have threatened human health. Therefore, it is important to focus on the food safety and agricultural soil pollution by heavy metals, especially for China where the demand for food production is increasing. This review comprehensively introduced the current status of agricultural soil pollution by heavy metals in China, analyzed the main sources of contaminants, including the applications of pesticides and fertilizers, atmospheric deposition related to vehicle emissions and coal combustion, sewage irrigation and mining. Food safety and agricultural soil pollution by heavy metals, the removal technologies for soil remediation such as soil amendments, phytoremediation and foliar sprays were also introduced. The review can provide significant insights for policymakers, environmental engineers, and agro-technicians regarding soil contamination control and management strategies and technologies. • The current status of agricultural soil pollution by heavy metals in China was comprehensively introduced. • The sources of heavy metal pollution in soil were analysed. • Remediation technologies for soil, including soil amendments, phytoremediation and foliar sprays were reviewed. [ABSTRACT FROM AUTHOR]

Geosynchronous orbit (GSO) is the ideal orbit for communication, navigation, meteorology and other satellites, but the space of GSO is limited, and there are still a large number of space debris threatening the safety of spacecraft. Therefore, real-time detection of GSO debris is necessary to avoid collision accidents. Because radar is limited by transmitting power and operating distance, it is difficult to detect GSO debris, so photoelectric detection becomes the mainstream way to detect GSO debris. This paper presents an adaptive real-time detection algorithm for GSO debris in the charge coupled device (CCD) images. The main work is as follows: An image adaptive fast registration algorithm and an enhanced dilation difference algorithm are proposed. Combining with mathematical morphology, threshold segmentation and global nearest neighbor (GNN) multi-target tracking algorithm, the functions of image background suppression, registration, suspected target extraction and multi-target tracking are realized. The processing results of a large number of measured data show that the algorithm can detect dim geostationary earth orbit (GEO) and non-GEO debris in GSO belt stably and efficiently, and the processing speed meets the real-time requirements, with strong adaptive ability, and has high practical application value. [ABSTRACT FROM AUTHOR]

The electrochemical reduction of nitrate (NO3−) to ammonia (NH3) has emerged as an attractive approach for selectively reducing NO3− to highly value-added NH3 and removing NO3− pollutants simultaneously. In this work, a heterostructured Co/Co3O4 electrocatalyst anchored on N-doped carbon nanotubes was prepared and applied for the NO3− reduction towards NH3 under alkaline conditions. The catalyst achieves outstanding performance with up to 67% NH3 faradaic efficiency at −1.2 V vs. Hg/HgO and 8.319 mg h−1 mgcat−1 yield at −1.7 V vs. Hg/HgO. In addition, it also exhibits good long-term stability. 15N isotopic labelling experiments prove that the yielded NH3 is derived from NO3− species. In situ electrochemical Raman spectra revealed that the structure of the as-prepared catalyst showed outstanding stability and identified possible intermediates during the electrocatalytic NO3− reduction reaction (NO3RR). [ABSTRACT FROM AUTHOR]

In most large field of view (FOV) observations, the distortion problem is inevitably and significantly more serious than in small FOV ones. In the circumstances, many traditional star identification approaches are not able to efficiently identify stars any more. In order to deal with this problem, we put forward a star identification method that is less sensitive to distortion. The method first processes stars in the central area of the image, using traditional identification logic, and then applies the region growing strategy to enlarge the identified regions iteratively until the entire image is covered. The performance of the new scheme is analysed in the presence of both simulated data and real data. The results show that the proposed algorithm has the advantage of speed, and the strategy of regional extension can efficiently identify stars in large FOV images compared with other existing algorithms. [ABSTRACT FROM PUBLISHER]

Hollow nanoreactors show great potential in catalysis due to the void‐confinement effect. Yet few studies have investigated the void‐confinement effect of hollow nanoreactors on intermediates. Herein, electrochemical NO reduction to NH3 (ENOR) is used as a probe reaction to study the void‐confinement effect of hollow Cu2O@CoMn2O4 nanoreactors on intermediates. Combined with the results of catalytic activity, H2‐treated in situ diffusion Fourier transform infrared spectroscopy and the finite‐element method simulation confirm that the void‐confinement effect on the intermediate is the main reason for enhanced ENOR efficiency. Additionally, theoretical calculations also show that the Cu sites of Cu2O@CoMn2O4 nanoreactors are favorable for the formation of *NOH intermediates. This work not only gives an insight into void‐confinement effect of hollow nanoreactors on intermediates but also provides a valuable strategy for improving ENOR. [ABSTRACT FROM AUTHOR]

Microplastic pollution has emerged as a pressing environmental issue of global concern due to its detrimental effects on the environment and ecology. Restricted to their characters of complex composition, it is a great challenge to propose a more cost-effective approach to achieve highly selective conversion of microplastic into add-value products. Here we demonstrate an upcycling strategy for converting PET microplastics into added-value chemicals (formate, terephthalic acid and K 2 SO 4). PET is initially hydrolyzed in KOH solution to produce terephthalic acid and ethylene glycol, which is subsequently used as an electrolyte to produce formate at the anode. Meanwhile, the cathode undergoes hydrogen evolution reaction to produce H 2. Preliminary techno-economic analysis suggests that this strategy has certain economic feasibility and a novel Mn 0.1 Ni 0.9 Co 2 O 4-δ rod-shaped fiber (RSFs) catalyst we synthesized can achieve high Faradaic efficiency (> 95%) at 1.42 V vs. RHE with optimistic formate productivity. The high catalytic performance can be attributed to the doping of Mn changing the electronic structure and reducing the metal-oxygen covalency of NiCo 2 O 4 , reducing the lattice oxygen oxidation in spinel oxide OER electrocatalysts. This work not only put forward an electrocatalytic strategy for PET microplastic upcycling but also guides the design of electrocatalysts with excellent performance. [Display omitted] • Micro-plastic PET was successfully converted into added-value chemicals (formate, TPA and K 2 SO 4). • High Faradaic efficiency (> 95%) was achieved at 1.42 V vs. RHE. • An optimistic formate productivity of 9.22 mmol cm−2 h−1 was achieved at 1.52 V vs. RHE. • Preliminary techno-economic analysis indicates that this strategy has certain economic feasibility. [ABSTRACT FROM AUTHOR]

Achieving synergy between single atomic site and charge transfer in heterojunction is significant for synthesising photocatalysts with excellent properties. In this paper, single atom Cu/Ta 3 N 5 /CdIn 2 S 4 S-scheme hierarchical polyhedrons (SACu/TN/CIS SHPs) have been successfully synthesized by a three-step simple chemistry process. We dive into the improvement of photocatalytic activity in the synergistic effect of SACu and S-scheme. The excellent charge separation and reducing the energy barrier during the ammonium production reaction in the synergistic effect were confirmed by density functional theory (DFT) calculations and physicochemical mechanistic investigations. Electron spin resonance (ESR) corroborated production of reducing agent to accelerate the progress of NO 3 − to NH 3. Under light conditions, the NH 3 production rate for SACu/TN/CIS SHPs is an astonishing ∼43.6 times higher than that of original Ta 3 N 5. This report not only recommends an efficient catalyst under visible light, but also proposes an advantageous solution for photocatalytic nitrate reduction in natural conditions. [Display omitted] • Single atom Cu/Ta 3 N 5 /CdIn 2 S 4 S-scheme hierarchical polyhedrons (SACu/TN/CIS SHPs) to facilitate NO x − to NH 3. • The synergistic effect of SACu/TN/CIS SHPs leads to NH 3 production rate of 256.32 μmol g−1 h−1 with 88.7 % selectivity. • The existence of Cu single atom effectively reduces the energy barrier during the reaction. • · CO 2 – activated by CdIn 2 S 4 hierarchical polyhedrons effectively enhance the conversion of NO 3 – to NH 3. • The formation of the S-scheme significantly enhance charge separation and facilitate the fully utilization of energy. [ABSTRACT FROM AUTHOR]