The protein phosphatase PC1 dephosphorylates and deactivates CatC to negatively regulate H2O2 homeostasis and salt tolerance in rice.

Catalase (CAT) is often phosphorylated and activated by protein kinases to maintain hydrogen peroxide (H2O2) homeostasis and protect cells against stresses, but whether and how CAT is switched off by protein phosphatases remains inconclusive. Here, we identified a manganese (Mn2+)-dependent protein phosphatase, which we named PHOSPHATASE OF CATALASE 1 (PC1), from rice (Oryza sativa L.) that negatively regulates salt and oxidative stress tolerance. PC1 specifically dephosphorylates CatC at Ser-9 to inhibit its tetramerization and thus activity in the peroxisome. PC1 overexpressing lines exhibited hypersensitivity to salt and oxidative stresses with a lower phospho-serine level of CATs. Phosphatase activity and seminal root growth assays indicated that PC1 promotes growth and plays a vital role during the transition from salt stress to normal growth conditions. Our findings demonstrate that PC1 acts as a molecular switch to dephosphorylate and deactivate CatC and negatively regulate H2O2 homeostasis and salt tolerance in rice. Moreover, knockout of PC1 not only improved H2O2-scavenging capacity and salt tolerance but also limited rice grain yield loss under salt stress conditions. Together, these results shed light on the mechanisms that switch off CAT and provide a strategy for breeding highly salt-tolerant rice.

Alloying Matters for Ordering: Synthesis of Highly Ordered PtCo Intermetallic Catalysts for Fuel Cells.

Porous carbon-supported atomically ordered intermetallic compounds (IMCs) are promising electrocatalysts in boosting oxygen reduction reaction (ORR) for fuel cell applications. However, the formation mechanism of IMC structures under high temperatures is poorly understood, which hampers the synthesis of highly ordered IMC catalysts with promoted ORR performance. Here, we employ high-temperature X-ray diffraction and energy-dispersive spectroscopic elemental mapping techniques to study the formation process of IMCs, by taking PtCo for example, in an industry-relevant impregnation synthesis. We find that high-temperature annealing is crucial in promoting the formation of alloy particles with a stoichiometric Co/Pt ratio, which in turn is the precondition for transforming the disordered alloys to ordered intermetallic structures at a relatively low temperature. Based on the findings, we accordingly synthesize highly ordered L10-type PtCo catalysts with a remarkable ORR performance in fuel cells.

Synthesis of rhodium intermetallic catalysts by enlarging the inter-particle distance on high-surface-area carbon black supports.

Here, we report a "critical distance" method for the synthesis of 9 kinds of sub-5 nm rhodium (Rh)-based intermetallic catalysts. Enlarging the distance between intermetallic particles on high-surface-area carbon black supports could significantly suppress the metal sintering in high-temperature annealing. The prepared Rh2Sn intermetallic catalysts exhibited enhanced activity in catalyzing the hydrogenation of nitrobenzene.

Self-assembled CsPbBr3 quantum dots with wavelength-tunable photoluminescence for efficient active jamming.

CsPbBr3 perovskite quantum dots (QDs) show great potential in various applications due to their size-dependent and excellent optoelectronic properties. However, it is still challenging to synthesize size-tunable CsPbBr3 QDs with purple emission. Herein, CsPbBr3 nanospheres (NS) with purple emission (432 nm) and wavelength-tunable photoluminescence were synthesized using a two-step recrystallization method for the first time. A nanocube (NC) strategy resulting from CsPbBr3 nanosphere self-assembly via polar solvent-induced surface ligand mismatch was proposed. The self-assembly process endows the QDs with wavelength-tunable photoluminescence ranging from 432 to 518 nm. The significant reduction in defects during self-assembly was confirmed by transient optical spectroscopy measurements, photoluminescence quantum yields (PLQY), and the disappearance of tail bands in the long-wavelength region of the photoluminescence (PL) spectrum. This theory demonstrated that the decrease in high defect surfaces and increase in specific surface area were the reasons for the decline in defects. Most importantly, these QDs could be used for the active jamming of optical imaging systems based on charged-coupled devices (CCDs), including laser imaging radar and low light level (LLL) night vision systems. QDs significantly increase the mean square error (MSE) of the image, while the detection rate of the target by the artificial intelligence algorithm decreased by 95.17%. The wide wavelength tunable emission caused by structural changes makes it arduous for silicon-based detectors to avoid the interference of QDs by adding filters or by other means.

Green and multifunctional chitosan-based conformal coating as a controlled release platform for fruit preservation.

Food waste caused by the decay of perishable foods is a serious global issue. However, traditional preservative materials don't perform well in preventing food decay. Here, a green and multifunctional conformal coating is prepared by the hydrogen-bonding interactions among chitosan, nano-humic acid and curcumin, which is different from traditional preservative films obtained by solution blending. Thanks to the formation of hydrogen-bonding network, the surface roughness of the coating increased from 9.43 nm to 33.3 nm, which makes it more matches with the micro/nano structure of the fruit surface and obtains a good coating effect for various fruits. Furthermore, this coating shows distinctive mechanical properties (the tensile strength of 31.4 MPa), antioxidant and antibacterial activities (the inhibition zone ≥5 mm), and can be used to control the long-term release (up to 38 days) of natural preservative onto fruit surfaces. Through the demonstration of four perishable fruits, the coating can keep freshness and appearance at least 9 days longer than the uncoated samples, confirming the universal effectiveness of the coating in preventing fruit decay. This coating is easy to produce and use, washable, degradable, and makes from cheap or waste renewable biomaterials, which does not cause additional health and environmental concerns.

Response Characteristics of Electric Potential and Its Relationship with Dynamic Disaster during Mining Activities: A Case Study in Xuehu Coal Mine, China.

Across the world, coal resource is widely utilized in industrial production. During coal mining activities, dynamic disasters may be induced, such as coal and gas outbursts, or rock burst, resulting in serious accidents or disasters. Previous studies have shown that electric potential (EP) signals can be produced during the deformation and fracture process of coal and rock mass under load. The abnormal response characteristics of EP can reveal the damage evolution and failure feather of coal mass. In this paper, the response characteristics of EP signals are analyzed with high gas testing during mining activities within deep coal seams, and the relationship between the EP response and outburst disaster hazard is studied. The results show that: (1) Under the comprehensive action of mining stress and gas effect, the coal mass was damaged and fractured, which can produce abundant EP signals, while the temporal EP response characteristics can reflect the loading state and damage evolution process inside the coal seam. (2) When coal cannon and a sudden increase of gas concentration occurred in the coal mass, the EP signal was at a high level and fluctuated violently. This can be regarded as precursory information for an outburst risk, which was verified by monitoring the results of mining stress and electromagnetic radiation (EMR). (3) Based on the unilateral inversion imaging method, EP spatial distribution law was studied and abnormal zones with high-value were identified. The zone is close to, or coincident with, the high value interval of EMR intensity and count indexes, which revealed the distribution characteristics of coal damage localization. Hence, EP monitoring results can forecast precursor information of outburst hazards temporally, and identify local zones with outburst hazard spatially. This study provides a new idea and application basis for using the EP method to monitor and prevent coal and rock dynamic disaster hazards in the field.

Pentacoordinate Al3+ Sites Anchoring Synthesis of Palladium Intermetallic Catalysts on Al2O3 Supports.

Size control of supported Pd-based intermetallic nanoparticles (i-NPs) remains a major challenge because the required high-temperature annealing for atomic diffusion and ordering easily causes metal sintering. Here, we described a pentacoordinate Al3+ site (Al3+penta) anchoring approach for the preparation of Pd-based i-NPs with controlled size, which takes advantage of the strong chemical interaction between Al3+penta sites and Pd-based i-NPs to realize size control. We synthesized six types of Pd-based i-NPs, and four of them can remain an average particle size of <6 nm. Furthermore, one of our prepared Pd-based i-NPs (that is, Pd3Pb) demonstrated outstanding performance in catalyzing the semihydrogenation of phenylacetylene.

Application of Image Fusion Algorithm Combined with Visual Saliency in Target Extraction of Reflective Tomography Lidar Image.

Reflective tomography Lidar has been proved to be a new Lidar system with long distance and high resolution. The reflective tomography Lidar image is prone to clutter and artifacts; thus, it is important for space target recognition to extract the target from the image. In this study, we proposed image fusion algorithm combined with visual saliency could be applied to the target extraction of reflective tomography Lidar image, which can not only preserve the target information but also eliminate the clutter and artifacts in the image. The efficiency of this algorithm is shown by simulation and the experiment of the reflective tomography Lidar system. Also, we analyzed the main source of reflective tomography Lidar image artifacts and the reason why this algorithm could remove clutter and artifacts.

Calculation of Stokes vector of laser backscattering from typical geometric rough surfaces at a long distance.

The polarization bidirectional reflectance distribution function is key to establishing the relationships between incident and backscattering Stokes vectors. For analytical calculation of Stokes vectors of backscattering light from rough surfaces of objectives at long distances, we treat complicated objectives as a combination of several typical geometric surfaces. The analytical calculation forms of Mueller matrices of typical geometric rough surfaces at different sizes and geometric parameters are presented using a microfacet model, and thus, the backscattering Stokes vectors are determined. Experimental results of four types of geometric forms show good agreement with theoretical simulation, except when the incident angle is larger than about 60° at a wavelength of 532 nm. Further studies should be focused on improving the microfacet model for fitting the experimental results at large incident angles, and effects of multiple reflections between different geometric surfaces cannot be neglected when the combination of typical geometric surfaces is considered.

High-Temperature Synthesis of Carbon-Supported Bimetallic Nanocluster Catalysts by Enlarging the Interparticle Distance.

Supported bimetallic nanoparticle catalysts with small size have attracted wide research attention in catalysis but are difficult to synthesize because high-temperature annealing required for alloying inevitably accelerates metal sintering and leads to larger particles. Here, we report a simple and scalable "critical interparticle distance" method for the synthesis of a family of bimetallic nanocluster catalysts with an average particle size of only 1.5 nm by using large-surface-area carbon black supports at high temperatures, which consist of 12 diverse combinations of 3 noble metals (Pt, Ru, and Rh) and 4 other metals (Cr, Fe, Zr, and Sn). In this strategy, high-temperature treatments ensure the formation of alloyed bimetallic nanoparticles and enlargement of the interparticle distance on high-surface-area supports significantly suppresses metal sintering. The prepared ultrafine Pt2Sn and RuSn nanocluster catalysts exhibited enhanced performance in catalyzing the synthesis of aromatic secondary amines and the selective hydrogenation of furfural, respectively.

[Clinical application of lumbar hyperextension MRI in the diagnosis of lumbar spinal stenosis].

OBJECTIVE: To evaluate the diagnostic value of lumbar hyperextension MRI, through studying the changes of spinal stenosis degree in lumbar hyperextension position. METHODS: From September 2018 to February 2020, 26 patients with lumbar spinal stenosis did lumbar spine neutral and hyperextension MRI scans. There were 11 males and 15 females, aged from 43 to 85 (64.00±10.37) years. As 6 patients induced and aggravated the symptoms of low back and leg pain in the hyperextension position, qualified MRI data could not be collected. Because of that, a total of 20 patients' qualified data were collected. Mimics Medical 21.0 medical image processing software was used to measure the relevant diagnostic parameters of lumbar spinal stenosis, analyze the change rules statistically, and evaluate the degree of lumbar spinal stenosis and changes in nerve compression in the hyperextension position. RESULTS: The sagittal diameter and cross sectional area of the lumbar spinal bony canal do not change significantly with the body position;the sagittal diameter of the dural sac, the sagittal diameter of the dural sac, and the disc yellow space all have different degrees of decline in the hyperextension position. CONCLUSION: For the imaging diagnosis of lumbar spinal stenosis, lumbar spine hyperextension position MRI can be a good complement for the routine neutral MRI examination, and it is more sensitive to the clinical diagnosis of lumbar spinal stenosis.

Sulfur-anchoring synthesis of platinum intermetallic nanoparticle catalysts for fuel cells.

Atomically ordered intermetallic nanoparticles are promising for catalytic applications but are difficult to produce because the high-temperature annealing required for atom ordering inevitably accelerates metal sintering that leads to larger crystallites. We prepared platinum intermetallics with an average particle size of <5 nanometers on porous sulfur-doped carbon supports, on which the strong interaction between platinum and sulfur suppresses metal sintering up to 1000°C. We synthesized intermetallic libraries of small nanoparticles consisting of 46 combinations of platinum with 16 other metal elements and used them to study the dependence of electrocatalytic oxygen-reduction reaction activity on alloy composition and platinum skin strain. The intermetallic libraries are highly mass efficient in proton-exchange-membrane fuel cells and could achieve high activities of 1.3 to 1.8 amperes per milligram of platinum at 0.9 volts.

Validating a segment on chromosome 7 of japonica for establishing low-cadmium accumulating indica rice variety.

Cadmium (Cd) contamination of rice is a serious food safety issue that has recently been gaining significant public attention. Therefore, reduction of Cd accumulation in rice grains is an important objective of rice breeding. The use of favourable alleles of Cd accumulating genes using marker-assisted selection (MAS) is theoretically feasible. In this study, we validated a segment covering OsHMA3-OsNramp5-OsNramp1 on chromosome 7 of japonica for establishing low-cadmium accumulating indica rice variety. The OsHMA3-OsNramp5-OsNramp1jap haplotype significantly decreased grain Cd concentration in middle-season indica genetic background. The improved 9311 carrying the OsHMA3-OsNramp5-OsNramp1jap haplotype with recurrent parent genome recovery of up to 91.6% resulted in approximately 31.8% decrease in Cd accumulation in the grain and with no penalty on yield. There is a genetic linkage-drag between OsHMA3-OsNramp5-OsNramp1 jap and the gene conditioning heading to days (HTD) in the early-season indica genetic background. Because the OsHMA3-OsNramp5-OsNramp1-Ghd7jap haplotype significantly increases grain Cd concentration and prolongs growth duration, the linkage-drag between OsHMA3-OsNramp5-OsNramp1 and Ghd7 should be broken down by large segregating populations or gene editing. A novel allele of OsHMA3 was identified from a wide-compatibility japonica cultivar, the expression differences of OsNramp1 and OsNramp5 in roots might contribute the Cd accumulating variation between japonica and indica variety.

High-Temperature Synthesis of Small-Sized Pt/Nb Alloy Catalysts on Carbon Supports for Hydrothermal Reactions.

Catalytic biomass conversions are sustainable processes to produce value-added fuels and chemicals but need stable catalysts that can tolerate harsh hydrothermal conditions. Herein, we report a hydrothermally stable catalyst by alloying Pt with a high-melting-point metal Nb. The Pt/Nb alloy catalysts are prepared by H2 reduction at a high temperature of 900 °C with a high-surface-area carbon black support, which can suppress metal sintering at high temperatures and thus lead to small-sized alloyed Pt/Nb particles of only 2.2 nm. Taking the advantages of surface acid property provided by the Nb sites and the size effect, the prepared C-supported small-sized Pt/Nb alloy catalysts exhibit attractive activities for the hydrogenation of levulinic acid into γ-valerolactone and the water-gas shift reaction. More significantly, benefiting from the inherent stability of high-melting-point Nb, the Pt/Nb alloy catalysts show much enhanced hydrothermal stability compared to commercial Pt/C and Ru/C catalysts.

Electronic Modulation of Pd-Based Bimetallic Catalysts with Sulfur-Doped Carbon Support for Phenylacetylene Semihydrogenation.

The semihydrogenation of phenylacetylene to styrene represents an important process for optimizing the polystyrene production and also a model reaction for the evaluation of selective hydrogenation catalysts. Although the alloying strategy and surface engineering for noble metal (particularly for Pd) catalysts can effectively inhibit the overhydrogenation of styrene, the selectivity of phenylacetylene semihydrogenation to styrene is generally below 95% near the full conversion. Here, we demonstrate the electronic modulation of Pd-based bimetallic nanocluster catalysts based on the strong metal-support interactions for improving the catalytic selectivity for phenylacetylene semihydrogenation. A series of Pd-M (M = Fe, Co, Ni, Cu, Ga) bimetallic nanoclusters of ∼2 nm are immobilized on mesoporous sulfur-doped carbon (meso_S-C) supports, which exhibit a high selectivity of >97% for the semihydrogenation of phenylacetylene to styrene. The strong interaction between metal and the meso_S-C supports enables the modulation of electronic structure of the bimetallic nanoparticles and thus leads to the selectivity enhancement for the phenylacetylene semihydrogenation.

Synthesis of carbon-supported sub-2 nanometer bimetallic catalysts by strong metal-sulfur interaction.

Small-sized bimetallic nanoparticles that integrate the advantages of efficient exposure of the active metal surface and optimal geometric/electronic effects are of immense interest in the field of catalysis, yet there are few universal strategies for synthesizing such unique structures. Here, we report a novel method to synthesize sub-2 nm bimetallic nanoparticles (Pt-Co, Rh-Co, and Ir-Co) on mesoporous sulfur-doped carbon (S-C) supports. The approach is based on the strong chemical interaction between metals and sulfur atoms that are doped in the carbon matrix, which suppresses the metal aggregation at high temperature and thus ensures the formation of small-sized and well alloyed bimetallic nanoparticles. We also demonstrate the enhanced catalytic performance of the small-sized bimetallic Pt-Co nanoparticle catalysts for the selective hydrogenation of nitroarenes.

A sulfur-tethering synthesis strategy toward high-loading atomically dispersed noble metal catalysts.

Metals often exhibit robust catalytic activity and specific selectivity when downsized into subnanoscale clusters and even atomic dispersion owing to the high atom utilization and unique electronic properties. However, loading of atomically dispersed metal on solid supports with high metal contents for practical catalytic applications remains a synthetic bottleneck. Here, we report the use of mesoporous sulfur-doped carbons as supports to achieve high-loading atomically dispersed noble metal catalysts. The high sulfur content and large surface area endow the supports with high-density anchor sites for fixing metal atoms via the strong chemical metal-sulfur interactions. By the sulfur-tethering strategy, we synthesize atomically dispersed Ru, Rh, Pd, Ir, and Pt catalysts with high metal loading up to 10 wt %. The prepared Pt and Ir catalysts show 30- and 20-fold higher activity than the commercial Pt/C and Ir/C catalysts for catalyzing formic acid oxidation and quinoline hydrogenation, respectively.

Transition metal-assisted carbonization of small organic molecules toward functional carbon materials.

Nanostructured carbon materials with large surface area and desired chemical functionalities have been attracting considerable attention because of their extraordinary physicochemical properties and great application potentials in catalysis, environment, and energy storage. However, the traditional approaches to fabricating these materials rely greatly on complex procedures and specific precursors. We present a simple, effective, and scalable strategy for the synthesis of functional carbon materials by transition metal-assisted carbonization of conventional small organic molecules. We demonstrate that transition metals can promote the thermal stability of molecular precursors and assist the formation of thermally stable polymeric intermediates during the carbonization process, which guarantees the successful preparation of carbons with high yield. The versatility of this synthetic strategy allows easy control of the surface chemical functionality, porosity, and morphology of carbons at the molecular level. Furthermore, the prepared carbons exhibit promising performance in heterogeneous catalysis and electrocatalysis.

Infrared Extinction Performance of Randomly Oriented Microbial-Clustered Agglomerate Materials.

In this study, the spatial structure of randomly distributed clusters of fungi An0429 spores was simulated using a cluster aggregation (CCA) model, and the single scattering parameters of fungi An0429 spores were calculated using the discrete dipole approximation (DDA) method. The transmittance of 10.6 µm infrared (IR) light in the aggregated fungi An0429 spores swarm is simulated by using the Monte Carlo method. Several parameters that affect the transmittance of 10.6 µm IR light, such as the number and radius of original fungi An0429 spores, porosity of aggregated fungi An0429 spores, and density of aggregated fungi An0429 spores of the formation aerosol area were discussed. Finally, the transmittances of microbial materials with different qualities were measured in the dynamic test platform. The simulation results showed that the parameters analyzed were closely connected with the extinction performance of fungi An0429 spores. By controlling the value of the influencing factors, the transmittance could be lower than a certain threshold to meet the requirement of attenuation in application. In addition, the experimental results showed that the Monte Carlo method could well reflect the attenuation law of IR light in fungi An0429 spore agglomerates swarms.

[Classification of hyperspectral imagery based on ant colony compositely optimizing SVM in spatial and spectral features].

A novel classification algorithm of hyperspectral imagery based on ant colony compositely optimizing support vector machine in spatial and spectral features was proposed. Two types of virtual ants searched for the bands combination with the maximum class separation distance and heterogeneous samples in spatial and spectral features alternately. The optimal characteristic bands were extracted, and bands redundancy of hyperspectral imagery decreased. The heterogeneous samples were eliminated form the training samples, and the distribution of samples was optimized in feature space. The hyperspectral imagery and training samples which had been optimized were used in classification algorithm of support vector machine, so that the class separation distance was extended and the accuracy of classification was improved. Experimental results demonstrate that the proposed algorithm, which acquires an overall accuracy 95.45% and Kappa coefficient 0.925 2, can obtain greater accuracy than traditional hyperspectral image classification algorithms.