MXene is a novel 2D lamellar material with excellent hydrophilicity and permselectivity. MXene was introduced in the P84 polymer matrix and the matrix was crosslinked with triethylenetetramine (TETA) ...to improve the permselectivity and solvent resistance of the polyimide membrane. The membrane was characterized with SEM, AFM and ATR-FTIR, and effects of MXene content on the membrane morphology and separation performance are investigated. The membrane prepared with 18% P84 and 1% MXene shows high rejection (100%) to gentian violet (408) and high flux (268 L·m−2·h−1) at 0.1 MPa and ambient temperature. MXene endows the membrane with much water channel and denser functional layer which improves the membrane performance obviously. The membrane shows excellent solvent resistance to dimethylformamide (DMF), acetone and methanol after crosslinking with TETA during the 18 days of immersion.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Underwater target recognition is an important supporting technology for the development of marine resources, which is mainly limited by the purity of feature extraction and the universality of ...recognition schemes. The low-frequency analysis and recording (LOFAR) spectrum is one of the key features of the underwater target, which can be used for feature extraction. However, the complex underwater environment noise and the extremely low signal-to-noise ratio of the target signal lead to breakpoints in the LOFAR spectrum, which seriously hinders the underwater target recognition. To overcome this issue and to further improve the recognition performance, we adopted a deep-learning approach for underwater target recognition, and a novel LOFAR spectrum enhancement (LSE)-based underwater target-recognition scheme was proposed, which consists of preprocessing, offline training, and online testing. In preprocessing, we specifically design a LOFAR spectrum enhancement based on multi-step decision algorithm to recover the breakpoints in LOFAR spectrum. In offline training, the enhanced LOFAR spectrum is adopted as the input of convolutional neural network (CNN) and a LOFAR-based CNN (LOFAR-CNN) for online recognition is developed. Taking advantage of the powerful capability of CNN in feature extraction, the recognition accuracy can be further improved by the proposed LOFAR-CNN. Finally, extensive simulation results demonstrate that the LOFAR-CNN network can achieve a recognition accuracy of 95.22%, which outperforms the state-of-the-art methods.
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CEKLJ, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
MXene, a new 2D transition metal carbide-based material, possesses excellent electrical conductivity and hydrophilicity. In this study, Ti
3
C
2
T
x
(where T represents a functional group (O, OH, ...and/or F)) was produced by etching and ultrasonicating Ti
3
AlC
2
. Then, it was used to prepare the MXene composite membrane
via
a simple filtration method performed at 0.2 MPa on a polyethersulfone (PES) ultrafiltration membrane. The MXene composite membrane shows excellent flux (115 L m
−2
h
−1
) and favorable rejection to Congo red dye (92.3% at 0.1 MPa). The membrane demonstrated rejection to inorganic salts below 23% with flux above 432 L m
−2
h
−1
at 0.1 MPa. Due to its loose lamellar structure, the composite membrane is able to demonstrate efficient permselectivity in the separation of dyes from salts. Furthermore, the composite membrane shows excellent hydrophilicity and flux because of the lamellar hydrophilic MXene.
MXene, a new 2D transition metal carbide-based material, possesses excellent permselectivity and hydrophilicity.
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IJS, KILJ, NUK, UL, UM, UPUK
Autism is a widespread neurodevelopmental disorder. The cause of autism is still unclear. Once it occurs, it will be accompanied for life. Intervention treatment is currently recognized as an ...effective method. With the rise of somatosensory technology, Kinect has gradually been applied to the field of autism rehabilitation with its natural human-computer interaction and game rehabilitation psychology. Because there is a great demand for autism rehabilitation training resources in China and the existing somatosensory rehabilitation equipment has some shortcomings, this study designed a set of somatosensory rehabilitation system for autistic children based on Kinect and carried out its rehabilitation effect with experimental demonstration. The specific research work mainly includes the following contents: first, aiming at the rehabilitation needs of children with autism, this article combines mainstream intervention treatment methods, using C# programming language and Windows Presentation Foundation (WPF) development technology to develop Kinect-based somatosensory game modules. The somatosensory rehabilitation game involves the training of the language communication, behavioral movement, daily life, sensory integration, and other comprehensive abilities of children with autism, which improves the shortcomings of the previous rehabilitation training in the scope of intervention. A variety of game types and diversified game modes are designed to meet the individual needs of rehabilitation training for children with autism. Second, experiments were carried out to verify the rehabilitation effect of the system. Using the Childhood Autism Rating Scale (CARS) and Pediatric Evaluation of Disability Inventory (PEDI) scale as the rehabilitation effect evaluation tools of this system, the experimental subjects were divided into the experimental group and control group, and different comparative experiments were conducted, respectively. Through the analysis of the scoring data of the CARS, it is found that the comprehensive ability of the experimental group of children receiving somatosensory rehabilitation training is significantly improved. Through the analysis of the scoring data of the PEDI scale, it is found that the children’s language communication, behavioral activities, and daily life abilities of the experimental group have been significantly enhanced. This article focuses on the design of the somatosensory game module of the autistic somatosensory rehabilitation system and the analysis of the system’s rehabilitation effect. It satisfies the training and rehabilitation needs of children with autism and has strong practical significance.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Electron-rich Ph2PC(R″)=CHPRR′ ligands bearing a P-alkyl group have been prepared and could be served as excellent ligands for the Cr-catalyzed ethylene tri-/tetramerization, exhibiting excellent ...catalytic performance with high activity and selectivity, and more importantly, a very low PE selectivity of ≤0.1 wt%. The backbone substitution and bridge unsaturation of carbon-bridged diphosphine ligands play an important role in the Cr-catalyzed ethylene tri-/tetramerization.
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•Electron-rich ligands used in the chromium-catalyzed ethylene tri-/tetramerization.•Remarkable influence of the σ-donor ability of ligand on the catalytic activity.•Significant influence of the steric property of ligand on the catalytic selectivity.•Catalytic system with a dialkyl phosphine showed high low-temperature activity.
Electron-rich Ph2PC(R″) = CHPRR′ ligands with a P-alkyl group were prepared, and, in conjunction with chromium, showed very high activities in ethylene tri-/tetramerization, leading to, in most cases, a very low PE selectivity of ≤0.1 wt%. The electronic property of ligands has a remarkable influence on the catalytic activity: the stronger the σ-donor ability, the higher the activity. Dialkyl phosphine ligands show a stronger σ-donor ability, and thus exhibited higher activities than their mixed alkyl/Ph phosphine counterparts. Reducing the ligand steric bulk could convert the selectivity from predominant trimerization into mixed tri-/tetramerization with 1-octene:1-hexene ratio of >1 without compromising high combined 1-C6/1-C8 selectivity (>90 wt%). Furthermore, the ligands with a dialkyl phosphine showed high low-temperature activity at 25 °C with a relatively high 1-C8 selectivity. Notably, under a lower pressure of 20–30 bar, using PPhiPr-PCCP 7 showed almost no formation of PE with high activity and selectivity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Cr(III) complexes supported by phenylene-bridged diphosphine ligands with P-alkyl substitution were prepared and evaluated in ethylene tri-/tetramerization. The ligand steric and electronic ...properties have significantly influenced the catalytic activity. The Cr complex 1 based on a bulky PCy2 phosphine ligand L 1 having a stronger σ-donor ability exhibited the highest activity, which is more reactive than its PPh2 counterpart 8. The selectivity toward ethylene tri-/tetramerization is mainly determined by the steric property of ligands. Reducing the ligand steric bulk switched the selectivity from predominant trimerization into mixed tri-/tetramerization. 1 achieved a high 1-hexene selectivity of 82.5 wt % with a 1-octene selectivity of 9.7 wt %, while 4 based on L4 bearing a less bulky PPhCy group gave a considerable 1-octene selectivity of 43.3 wt % with a very high activity of 1874 kg·gCr –1·h–1. 1 also exhibited a high activity even at a relatively low temperature of 40 °C, while both 4 and 5 based on a PPh(alkyl) diphosphine ligand gave poor activities at 40 °C. More importantly, these Cr complexes showed a very low PE selectivity of ≤0.1 wt %.
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IJS, KILJ, NUK, PNG, UL, UM
To further strengthen the AlCoCrFeNi high-entropy alloy (HEA) coating prepared by high-speed laser cladding (HLC), laser remelting (LR) was chosen to reprocess it. The effects of LR on the ...topography, microstructure, growth orientation, phase distribution, and properties were investigated. It was revealed that there were a large number of liquid phase separation (LPS) zones in the HLC coating because of an ultrafast cooling rate. After LR, the LPS zones were eliminated. Compared to HLC coating, the microhardness increased from 622 HV to 762 HV, and the friction coefficient and the wear weight loss were reduced by 0.1 and 0.5 mg, respectively. In electrochemical testing, the self-corrosion potential increased by 45.9 mV and the self-corrosion current density decreased by one order of magnitude. Meanwhile, EBSD analysis indicated that the LPS zones were prone to recrystallization. The LPS zones were nickel-poor, low hardness, also BCC phase, and had a clearer (101) orientation. With the elimination of the LPS zones, the kernel average misorientation values were reduced, Taylor factor values and high angle grain boundaries were increased, and the average grain size was reduced from 2.43 μm to 2.12 μm. Eventually, for LR coatings, the combination of fine grain strengthening, solid solution strengthening, spalling reduction, and Cr element segregation resulted in better wear and corrosion resistances. The overall results show that a reasonable LR application can induce the microstructure of the HLC coating and improve its service properties.
● The AlCoCrFeNi high-entropy alloy coatings were prepared by high-speed laser cladding (HLC) and reprocessed by laser remelting (LR).● There were a large number of liquid phase separation (LPS) zones in the HLC coating. After LR, the LPS zones were replaced by fine equiaxed crystals.● The LPS zones were nickel-poor and low hardness, had a clearer (101) orientation, and tended to spall off in the wear test, causing a decrease in the overall wear resistance of the coating.● As a result of the elimination of the LPS zones, the microhardness and wear resistance of the LR coating were improved by solid solution strengthening and fine grain strengthening.● Appropriate undercooling and more high angle grain boundaries caused by LR provided a larger driving force for grain boundary segregation. The elemental content of Cr at the grain boundaries became higher, and the corrosion resistance of the LR coatings increased significantly. Display omitted
•HLC led to a large number of the LPS zones in the AlCoCrFeNi HEA coating.•LR could successfully eliminate the LPS zones.•Recrystallization made the grains of the LPS zones coarse and soft.•The microhardness and wear resistance of the coating were improved by LR.•Higher Cr content at grain boundaries boosted corrosion resistance of LR coating.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Mixed alkyl/aryl diphos ligands have been prepared and their application in iron‐catalyzed cross coupling of benzylic chlorides with diaryl zinc (Negishi) or aryl Grignard reagents (Kumada) towards ...the synthesis of diarylmethane has been evaluated. The iron−diphos catalytic system exhibited the enhanced activity and selectivity in the two coupling reactions. The electron‐rich mixed PPh2/PCy2 ligands outperformed their symmetrical PPh2 congeners, and led to decreased homocoupling byproduct formation. It indicates that the electronic effect of the ligands plays an important role in the catalytic performance. The Fe catalyst supported by L8 bearing an electron‐rich PCy2 substituent and a sterically demanding tert‐butyl on ethene backbone exhibited the best catalytic performance and good functional group tolerance in the two cross coupling reactions.
C−C coupling: Iron catalysts supported by mixed alkyl/aryl diphos ligands exhibited efficient reactivities in both Negishi and Kumada coupling towards the synthesis of diarylmethane with enhanced activity and selectivity. The electron‐rich mixed PPh2/PCy2 ligands outperformed their symmetrical PPh2 congeners, and led to decreased homocoupling byproduct formation.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
The AlCoCrFeNi high-entropy alloy coatings were prepared by laser cladding (LC) and reprocessed by laser remelting (LR). Laser remelting caused cracks on the coating surface, but the cracks of ...boronized laser remelting (LR-B) coating were significantly suppressed. Compared to the LR coating, the microhardness of the LR-B coating increased from 643 HV to 1008 HV, the friction coefficient decreased from 0.55 to 0.45, and the self-corrosion potential increased by 134 mV. The crack elimination contributed to the transition of 25% of the BCC phase to the FCC phase. The property enhancement was mainly due to the fine grain strengthening, dislocation strengthening, and Cr2B reinforced particles as reinforced phase.
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•A trace amount of boron was doped in the protective gas during laser remelting.•The cracks of the boronized laser remelting (LR-B) coating were significantly suppressed.•With the addition of boron, the FCC phase and Cr2B were formed.•The Cr2B second-phase strengthening increased microhardness and wear resistance.•The Cr2B particles in the LR-B coating resulted in excellent corrosion resistance.
To avoid cracking of the AlCoCrFeNi high-entropy alloy (HEA) coating during laser remelting (LR), a trace amount of boron (B) was doped in the protective gas. Compared to the LR coating, the cracks of the boronized laser remelting (LR-B) coating were significantly suppressed, the microhardness increased from 643 HV to 1008 HV, the friction coefficient decreased from 0.55 to 0.45, and the self-corrosion potential increased by 134 mV. The crack elimination mainly contributed to the transition of 25 % of the BCC phase to the FCC phase, and the property enhancement was due to the fine grain strengthening, dislocation strengthening, and Cr2B reinforced particles generation. This novel finding can be applied to other BCC structure HEA coatings for macroscopic crack control and optimization of wear and corrosion resistances.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•New Cr(III) catalysts supported by the diphosphinoindole ligands.•The Cr(III) catalysts for the selective ethylene trimerization and tetramerization.•The effect of ligand substitution on the ...catalytic performance has been evaluated.
A new class of diphosphinoindole ligands have been developed. Upon activation with MMAO-3A, Cr catalysts supported by these bisphosphine ligands are active for ethylene tri-/tetramerization. The best result was achieved by using the bisphosphine ligand containing a phenyl group at C3 position of indole, giving a high activity of up to 364 kg/(g Cr/h) with a total selectivity of up to 72% toward 1-hexene (23.5%) and 1-octene (48.4%). A representative chromium tetracarbonyl complex was synthesized and structurally characterized by single-crystal X-ray diffraction.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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