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A new type of reduced graphene oxide‐encapsulated silicon nitride (Si3N4@rGO) particle was synthesized via an electrostatic interaction between amino‐functionalized Si3N4 particles and graphene oxide (GO). Subsequently, the Si3N4@rGO particles were incorporated into a Si3N4 matrix as a reinforcing phase to prepare nanocomposites, and their influence on the microstructure and mechanical properties of the Si3N4 ceramics was investigated in detail. The microstructure analysis showed that the rGO sheets were uniformly distributed throughout the matrix and firmly bonded to the Si3N4 grains to form a three‐dimensional carbon network structure. This unique structure effectively increased the contact area and load transfer efficiency between the rGO sheets and the matrix, which in turn had a significant impact on the mechanical properties of the nanocomposites. The results showed that the nanocomposites with 2.25 wt.% rGO sheets exhibited mechanical properties that were superior to monolithic Si3N4; the flexural strength increased by 83.5% and reached a maximum value of 1116.4 MPa, and the fracture toughness increased by 67.7% to 10.35 MPa·m1/2. [ABSTRACT FROM AUTHOR]

Aiming to improve the performance of self‐lubricating ceramic tools, an advanced self‐lubricating ceramic composite was developed. Core‐shell structure CaF2@Al2O3 powders were synthesized by liquid‐phase non‐uniform nucleation method. Al2O3/Ti(C,N)/CaF2@Al2O3 composite made by adding CaF2@Al2O3 powders exhibited notable improvements in microstructure and mechanical properties as compared with Al2O3/Ti(C,N)/CaF2 composite made by adding uncoated CaF2 powders. The core‐shell coated self‐lubricating ceramic tool with different content of CaF2@Al2O3 was designed and prepared by hot pressing sintering process. The results show that when the content of CaF2@Al2O3 is 10 vol%, The composite has the best mechanical properties, the flexural strength, and the fracture toughness and the hardness is 680 MPa, 6.50 MPa·m1/2, and 17.29 GPa. Compared with the tool material with only CaF2 solid lubricant added, the above performances were increased by 8.91%, 29.48%, and 14.50% respectively. The influence of different CaF2@Al2O3 content on the physical and mechanical properties and microstructure of the tool material was analyzed. [ABSTRACT FROM AUTHOR]

A Rh(III)-catalyzed unsymmetrical C-H alkylation and amidation of N-phenoxyacetamides with diazo compounds has been developed under mild and redox-neutral conditions, producing dinitrogen as the only byproduct. The reaction represents the first example of one-step, unsymmetrical difunctionalization of two ortho- C -- H bonds. Experimental and computational studies support that N-phenoxyacetamides most likely undergo an initial ortho-C -- H alkylation with diazo compounds via a Rh(III)-catalyzed C -- H activation, and the resulting Rh(III) intermediate subsequently undergoes an intramolecular oxidative addition into the O -- N bond to form a Rh(V) nitrenoid species that is protonated and further directed toward electrophilic addition to the second ortho position of the phenyl ring. This work might provide a new direction for unsymmetrical C -- H difunctionalization reactions in an efficient manner. [ABSTRACT FROM AUTHOR]

The state-of-the-art performance on entity resolution (ER) has been achieved by deep learning. However, deep models usually need to be trained on large quantities of accurately labeled training data, and cannot be easily tuned towards a target workload. However, in real scenarios, there may not be sufficient training data; even if they are abundant, their distribution is almost certainly different from target data to some extent. To alleviate such limitation, this paper proposes a novel risk-based adaptive training approach for ER that can tune a deep model towards its target workload by the workload's particular characteristics. Built on the recent advances on risk analysis for ER, the proposed approach first trains a deep model on labeled training data, and then fine-tunes it on unlabeled target data by minimizing its misprediction risk. Our theoretical analysis shows that risk-based adaptive training can correct the label status of a mispredicted instance with a fairly good chance. Finally, we empirically validate its efficacy on real benchmark data by a comparative study. Our extensive experiments show that it can considerably improve the performance of deep models. Furthermore, in the scenario of distribution misalignment, it can similarly outperform the state-of-the-art alternatives of transfer learning by considerable margins. Using ER as a test case, we demonstrate that risk-based adaptive training is a promising approach potentially applicable to various challenging classification tasks. [ABSTRACT FROM AUTHOR]

An unprecedented rhodium(III)-catalyzed regioselective redox-neutral annulation reaction of 1-naphthylamine N-oxides with diazo compounds was developed to afford various biologically important 1 H-benzo[g]indolines. This coupling reaction proceeds under mild reaction conditions and does not require external oxidants. The only by-products are dinitrogen and water. More significantly, this reaction represents the first example of dual functiaonalization of unactivated a primary C(sp3)H bond and C(sp2)H bond with diazocarbonyl compounds. DFT calculations revealed that an intermediate iminium is most likely involved in the catalytic cycle. Moreover, a rhodium(III)-catalyzed coupling of readily available tertiary aniline N-oxides with α-diazomalonates was also developed under external oxidant-free conditions to access various aminomandelic acid derivatives by an O-atom-transfer reaction. [ABSTRACT FROM AUTHOR]

Liquid‐phase laser irradiation technology was utilized to synthesize graphene‐coated tungsten carbide (WC@G) core–shell composite materials with regular spherical morphology. Characterization via scanning electron microscopy, transmission electron microscopy (TEM), X‐ray diffraction, and Raman spectroscopy revealed the evolution of WC particle microstructure from sharp edges to regular spherical shapes post‐laser irradiation. High‐resolution TEM displayed a tightly knit core–shell structure. Raman spectroscopy confirmed graphene presence through D, G, and 2D peaks. Incorporation of WC@G into a titanium diboride matrix, followed by discharge plasma sintering, yielded TiB2/WC@G composite ceramic materials. Compared to TiB2/WC/G composite ceramic materials, the WC@G core–shell structure significantly enhanced sintering performance. Optimal mechanical properties were achieved with 6 wt.% WC@G, exhibiting a relative density of 99.6%, Vickers hardness of 18.5 GPa, flexural strength of 696.9 MPa, and fracture toughness of 8.5 MPa m1/2. Characterization identified graphene detachment, pull‐out, and fracture deflection as key mechanisms enhancing toughness in TiB2/WC@G composite ceramic materials. [ABSTRACT FROM AUTHOR]

To improve the mechanical characteristics and machinability of Ti(C,N) cermet and broaden its application range, Al2O3@Ni core–shell powders with varying Ni concentrations were generated using the heterogeneous precipitation-thermal reduction method, and Al2O3@Ni core–shell powders-reinforced Ti(C,N) cermet was created using spark plasma sintering (SPS). The mechanical, microstructural, and sintering characteristics of Ti(C,N) cermet were examined using core–shell powders with varying Ni contents. Al2O3@Ni core–shell powders with appropriate Ni content may uniformly distribute Ni with magnetic solid characteristics in cermet materials, resulting in rapid and uniform discharge that increases interface bonding, improves sintering, and greatly improves overall mechanical qualities. After adding core–shell powders, the cutting force of the TA@30N cermet tool is reduced compared to the TA30N cermet tool, but the surface quality of the machined workpiece improves. The effective cutting distance of the TA@30N cermet tool on heat-treated 45# steel is 36,000 m, 33.33% greater than that of the homogeneous TA30N cermet tool. [ABSTRACT FROM AUTHOR]

To enhance the fracture toughness of B4C ceramics, B4C/TiB2 ceramics with excellent performance were prepared by using TiO2 as the addition item and using spark plasma sintering to introduce TiB2 based on in situ reaction, which was compared with ceramics directly introduced with TiB2, the impacts of TiO2 content, temperature and holding time on B4C/TiB2 ceramics were studied, and the toughening mechanism of B4C/TiB2 ceramics in situ reaction was discussed. The results showed that compared with the ceramics directly introduced with TiB2, B4C/TiB2 ceramics with reinforcement phase TiB2 introduced through in‐situ reaction were easier to obtain higher relative density and better properties. Due to the existence of a discharge effect and the application of pulse current, B4C/TiB2 ceramics with excellent comprehensive properties can be prepared at lower temperatures and short time. When 15 vol% TiO2 was added, the temperature was 1750°C and the holding time was 10 min, the comprehensive properties were better, and their relative density, Vickers hardness, flexural strength, and fracture toughness were 98.5%, 27.72 GPa, 474 MPa, and 5.08 MPa·m1/2, respectively. Toughening mechanisms such as crack deflection, crack branching, and crack bridging improved the fracture toughness. [ABSTRACT FROM AUTHOR]

In order to develop a new ceramic tool material with self-repairing capability, Al2O3/TiC/TiB2 ceramic tool material was prepared by vacuum hot-pressure sintering method. The toughening and strengthening mechanism of TiB2 on Al2O3/TiC substrate was analyzed. The results show that the ceramic tool material has good comprehensive mechanical properties when the TiB2 content is 10 vol.%. Its flexural strength was 701.32 MPa, hardness was 18.3 GPa, and fracture toughness was 6.2 MPa·m1/2, which were improved by 11.6%, 2.2% and 16.1% respectively, compared with the Al2O3/TiC tool material. Fracture surfaces of the Al2O3/TiC/TiB2 ceramic tool material were characterized by SEM, EDS and XRD. The results showed that the fracture mode was a mixture of transgranular fracture and intergranular fracture. The growth of Al2O3 and TiC grains can be effectively inhibited by adding appropriate amount of TiB2, and the internal grains of the material can be refined. The TiB2 has a uniform distribution in the matrix and acts as a diffusion toughening agent. The cutting performance of Al2O3/TiC/10 vol.%TiB2 tool material was further investigated. Experiments conducted on tools made of Al2O3/TiC and Al2O3/TiC/TiB2 materials showed that the main forms of wear for both tools were abrasive wear and bonded wear. The friction coefficient of Al2O3/TiC/TiB2 tools was reduced by 10.77% compared to Al2O3/TiC tools. [ABSTRACT FROM AUTHOR]

With increasing connectedness, network intrusion has become a critical security concern for modern information systems. The state-of-the-art performance of Network Intrusion Detection (NID) has been achieved by deep learning. Unfortunately, NID remains very challenging, and deep models may still mislabel many activities in real networks. Therefore, there is a need for risk analysis, which aims to know which activities may be mislabeled and why. In this paper, we propose a novel solution of interpretable risk analysis for NID that can rank the activities by their mislabeling risk. Built upon the existing framework of LearnRisk, it first extracts interpretable risk features and then trains a risk model by a learning-to-rank objective. It constructs risk features based on domain knowledge of network intrusion as well as statistical characteristics of activities. Furthermore, we demonstrate how to leverage risk analysis to improve prediction accuracy of deep models. Specifically, we present an adaptive training approach for NID that can effectively fine-tune a deep model towards a particular workload by minimizing its misprediction risk. Finally, we empirically evaluate the performance of the proposed solutions on real benchmark data. Our extensive experiments have shown that the proposed solution of risk analysis can identify mislabeled activities with considerably higher accuracy than the existing alternatives, and the proposed solution of adaptive training can effectively improve the performance of deep models by considerable margins in both offline and online settings. [ABSTRACT FROM AUTHOR]

Aiming at the contradiction between the lubricating performance and mechanical performance of self-lubricating ceramic tools. CaF2@Al(OH)3 particles were prepared by the heterogeneous nucleation method. An Al2O3/Ti(C,N) ceramic tool with CaF2@Al2(OH)3 particles and ZrO2 whiskers was prepared by hot press sintering (frittage). The cutting performances and wear mechanisms of this ceramic tool were investigated. Compared with the Al2O3/Ti(C,N) ceramic tool, the Al2O3/Ti(C,N)/ZrO2/CaF2@Al(OH)3 ceramic tool had lower cutting temperatures and surface roughness. When the cutting speed was increased from 100 m/min to 300 m/min, a lot of CaF2 was smeared onto the surface of the ceramic tool, and the flank wear of the Al2O3/Ti(C,N)/ZrO2/CaF2@Al(OH)3 ceramic tool was reduced. The main wear mechanisms of the Al2O3/Ti(C,N)/ZrO2/CaF2@Al(OH)3 ceramic tool were adhesive wear and micro-chipping. The formation of solid lubricating film and the improvement of fracture toughness by adding ZrO2 whiskers and CaF2@Al(OH)3 were important factors for the Al2O3/Ti(C,N)/ZrO2/CaF2@Al(OH)3 ceramic tool to have better cutting performances. [ABSTRACT FROM AUTHOR]

The aim of the present work was to investigate in detail the influence of running-in with acetylacetone on the friction behavior of 5CB liquid crystal between steel surfaces. Friction tests were carried out using a sliding ball-on-disk tribometer. The coefficient of friction (COF) decreased significantly after a running-in process with acetylacetone. Tribochemical reactions between steel and acetylacetone generated Fe(acac)3 and groove-structured wear on the ball. Their synergistic effect is the reason for the ultralow friction, and without either one, the COF increases. Special attention was given to the rheological behavior of 5CB. Shear history has a significant influence on the viscosity and storage moduli of 5CB. In addition, the COF under the same low speed decreased by 37% after a friction test at higher speed. The possible mechanism is discussed, and an in-depth understanding of this tribological system is needed to develop possible future applications. [ABSTRACT FROM AUTHOR]

In this paper, by adding Co, Mo, and Ni metal binder and using spark plasma coupling high-frequency induction (SP–HF) sintering technology, high-entropy (W,Nb,Mo,Ta,Ti)C cermet with good performance was successfully prepared at 1350 °C. The sintering temperature was much lower than that of the solid-state sintering temperature adopted for high-entropy carbide ceramics (about 2000 °C) while maintaining high hardness and fracture toughness. The effects of sintering temperature, holding time and sintering pressure on the mechanical properties of high-entropy (W,Nb,Mo,Ta,Ti)C cermet were investigated. The experimental results show that the SP-HF sintering can promote the liquid phase flow inside the high-entropy (W,Nb,Mo,Ta,Ti)C cermet and improve the density. The high-frequency induction sintering effect of the high-intensity magnetic metal binder phase (Co, Ni) promotes the rapid diffusion of the constituent phases using the vacancy mechanism and the metal liquid phase, which helps to form a high-entropy cermet solid solution at a lower temperature. The different high-entropy effects of the inner and outer layers of high-entropy (W,Nb,Mo,Ta,Ti)C cermet materials play a role in strengthening and toughening the materials, and effective solid solution strengthening is the main reason for improving mechanical properties. The mechanical properties of high-entropy (W,Nb,Mo,Ta,Ti)C cermet are the optimized at 1350 °C, holding time of 8 min, and sintering pressure of 35 MPa. The Vickers hardness, fracture toughness, and flexural strength are 18.38 ± 0.19 GPa, 9.65 ± 0.25 MPa · m1/2 and 970 ± 30 MPa, Vickers hardness was measured at 49 N load. [ABSTRACT FROM AUTHOR]

To prepare a self-lubricating ceramic tool with excellent mechanical properties and crack healing ability, the h-BN@Al 2 O 3 solid lubricant with a core-shell structure was prepared by the heterogeneous nucleation method, and was added into Al 2 O 3 /TiC ceramic matrix together with TiB 2. Examination of the micro-morphology and phase composition of h-BN@Al 2 O 3 found that the surface of the solid lubricant h-BN was coated with Al(OH) 3 at first, and after calcination at 1200 °C, a dense and uniform Al 2 O 3 shell was formed. At the same time, the effects of the h-BN@Al 2 O 3 addition on the ceramic tool material were studied. The mechanical properties of the ceramic tool material with h-BN@Al 2 O 3 were improved relative to than those with h-BN. The optimal content of h-BN@Al 2 O 3 solid lubricant was 5 vol%. In the friction and wear test, h-BN in h-BN@Al 2 O 3 particles can be stripped to form a solid lubricating film on the material surface, which plays a good role in reducing wear and resisting wear. The crack healing ability of the self-lubricating ceramic tool material was studied by prefabricating cracks with a length of 400 μm on the surface. After a heat treatment at 700 °C for 60 min, the surface cracks of the ceramic tool material were completely healed, and the flexural strength was restored to 90% of that of the smooth samples. The oxidation of TiB 2 and h-BN in ceramic tool materials is the main reason for crack healing. [ABSTRACT FROM AUTHOR]

The interfacial mechanical properties of the alumina/graphene (Al2O3/GR) nanocomposite ceramic tool materials were studied by molecular dynamic simulations. The effects of pull‐out velocity of graphene, system temperature, vacancy defect, and wrinkled graphene on the interfacial mechanical properties were investigated. Results show that a large interfacial shear stress (382 MPa) exists between the Al2O3/GR interface. The maximum pull‐out force and interfacial shear stress increase with increasing graphene pull‐out velocity. The increase of temperature reduces the maximum pull‐out force and interfacial shear stress. Moreover, the load transfer capacity is reduced and the creep of the matrix occurs. These factors reduce the fracture toughness of the Al2O3/GR nanocomposites. A moderate amount of vacancy defects in graphene increases the interfacial pull‐out force and shear stress of Al2O3/GR nanocomposite ceramic tool. Compared with Al2O3/GR nanocomposite ceramic tools, the interfacial interaction energy and shear stress of pleated graphene and Al2O3 were increased by 13.87% and 41.08% respectively, with better toughening and reinforcement. The results are of significance in further understanding of the interfacial mechanical properties at the nanoscale and then beneficial to improve the mechanical properties and engineering performance of Al2O3/GR composite ceramic materials. [ABSTRACT FROM AUTHOR]

A novel Rh(III)-catalyzed regioselective and redox-neutral annulation reaction of 1-naphthylamine N-oxides with α-diazomalonates is developed. [ABSTRACT FROM AUTHOR]

For addressing the issue of low relative density, poor fracture toughness of boron carbide ceramics, carbon nanotubes (CNTs)‐reinforced B4C‐SiC ceramic composite material was prepared via spark plasma sintering (SPS), and the impact of CNTs on the strengthening and toughening of the composite was studied. The evidence revealed that an appropriate amount of CNTs can enhance the discharge effect and improve the compactness. As the CNTs content increased, the flexural strength and fracture toughness took on a tendency to first rise and then drop. After mixing.5 wt.% CNTs, the flexural strength and fracture toughness were 499 MPa and 5.38 MPa·m1/2, which increased by 59.4% and 28.4%, respectively. The transformation of fracture mode, grain refinement, bridging and pulling‐out of CNTs efficiently enhance the mechanical properties. [ABSTRACT FROM AUTHOR]

In this study, 3 mol% yttria‐stabilized tetragonal zirconia polycrystal (3Y‐TZP)/Al2O3/graphene nanoplatelets (GNPs) medical ceramic materials for manufacturing surgical scalpels were sintered in vacuum in an SPS–625HF furnace. The mechanical performances and microstructures of the composites were investigated, and the influence mechanisms of the sintering temperature and amount of added GNPs were studied. During the sintering process at 1400°C and 30 MPa for 5 min, the added GNPs enhanced the mechanical properties of the 3Y‐TZP/Al2O3 composites. The results showed that the composite with.1 wt.% GNPs had 6.4% (910 ± 11 MPa) higher flexural strength than 3Y‐TZP/Al2O3. The composite with.4 wt.% GNPs had 38.7% (12.95 ±.22 MPa m1/2) greater fracture toughness than 3Y‐TZP/Al2O3. The main toughening mechanisms of 3Y‐TZP/Al2O3/GNPs were crack bridging, crack deflection, crack branching, GNPs bridging, transgranular fracture structures, and phase transformation of t‐ZrO1.95. The two‐stage densification displacement curve appeared at the optimal sintering temperature of the materials, and the 3Y‐TZP/Al2O3/GNPs composites with a two‐stage densification displacement curve had excellent mechanical properties. The added GNPs can inhibit the grain growth during the sintering process, thereby refining the zirconia grains. With the increase in GNPs content, the grain size and flexural strength of the composites decreased gradually. However, higher content of GNPs was beneficial to improve the relative density and thermal diffusivity of 3Y‐TZP/Al2O3/GNPs composite material. [ABSTRACT FROM AUTHOR]