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A promising approach for implementing biomimetic systems relies on organic electronic devices designed to emulate neural synapses. However, organic artificial synapses face challenges in achieving high yield and robustness, rendering them difficult to use in practical applications. In this work, a high-yield and highly stable bulk heterojunction (BHJ) synaptic device composed of Poly(3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) was fabricated via a simple solution process followed by thermal treatments. The crystallinity of P3HT and the precipitation of PCBM in BHJ films can be controlled by the thermal annealing temperatures. At 80 °C, P3HT reaches its highest crystallinity, while PCBM remains uniformly distributed. This thermal treatment significantly contributes to the fabrication of devices characterized by a high yield rate, reaching 98.43%. Additionally, this device remained operational even after being immersed in deionized water, ethanol, and seawater for 100 h. More importantly, it exhibited high elasticity over a wide temperature range from −90 to 310 °C. Finally, this device was utilized to construct a biomimetic vehicle with autonomous memory learning capabilities. After repeated training, the avoidance time was optimized by 31.4%. The robust P3HT:PCBM artificial synapses hold great promise for advancing the development of biomimetic electronic products in extreme environments.

This study proposes a secondary cutting technique to address the chip breaking issue of cermet cutting tools. A cemented carbide blade is superimposed to cut off the chips while cutting with (Ti,W)C cermet tools, this approach allows for achieving chip breaking while maintaining excellent machining surface integrity. In this paper, the influence of the distance between the secondary cutting tool and the major cutting edge and the thickness of the tool on the chip breaking is studied, by using the combination of finite element simulation and experimental verification. The results indicate that the secondary cutting technique transforms the chips from long helical chips into dual-C-type chips. The distance between the secondary cutting tool and the major cutting edge is the primary factor affecting chip breaking. The reason is that the free end of the chip is subjected to the reaction force of the secondary cutting tool, which hinders the increase of the chip curl radius, increases the internal strain, and achieves the chip breaking condition. The thickness of the secondary cutting tool is also a significant factor influencing chip breaking, when the thickness reaches the critical value of 1.8 mm, the tool transitions from obstructive action to cutting action. When the cutting material is 45 steel, the cutting speed is 300 m/min, the feed rate is 0.142 mm/r, and the cutting depth is 0.2 mm, the distance between the secondary cutting tool and the major cutting edge is 1.5 mm, and the tool thickness is 1.3 mm, the chip breaking effect is the best, the main types of chips is dual-C type chips, with a chip length of 7.1 mm ± 0.3 mm and a chip fracture curl radius of 1.8 mm ± 0.1 mm. At this point, the surface roughness can be reduced to as low as 0.98 μm, good surface integrity is ensured while chip breaking.

Graphical abstract:

In machining processes, the high temperature and stress can lead to plastic deformations of the workpiece material. Thermomechanical loading has a significant impact on the microstructure of the machined surface, including grain deformation, recrystallization, and refinement. Among these factors, grain refinement plays a crucial role in determining the mechanical properties of the materials. To investigate the mechanism of grain refinement on the machined surface of Inconel 718 at different cutting speeds, the experiments and finite element simulations were conducted. The microstructural characteristics were quantitative analyzed, including grain size, grain boundary distribution characteristics, average orientation (KAM), and geometrically necessary dislocation (GND) density distribution. The mapping relationship between the multi-physical fields (equivalent plastic strain, temperature) during cutting and the microstructural evolution of Inconel 718 was established. The research indicated that the increasing the cutting speed leads to a higher degree of grain refinement. At a cutting speed of 450 m/min, the maximum grain refinement is achieved with an approximately grain size of 2.48 μm. The contribution from plastic deformation (dynamic recuperation) gradually increases while high temperature remains dominant as factors influencing grain refinement. Conversely, the equivalent plastic strain becomes the primary factor contributing to grain refinement, with a gradual increase in the proportion due to dynamic recrystallization at cutting speeds of 250 m/min and 350 m/min.

A sandwich structure with a sound design helps the cermet tool's surface form residual compressive stress, which enhances the tool's cutting and mechanical capabilities. In this study, a sandwich cermet tool has been created and constructed with Al2O3fibers added to the middle layer of the (Ti,W)C sandwich cermet tool. The (Ti,W)C sandwich cermet tool's physical model is constructed, and using FEM modeling, an exploration was undertaken to examine how the residual stress is affected by the Al2O3fiber content and thickness of the middle layer. To gain a deeper insight into the cutting performance of the sandwich cermet tool, dry cutting trials are carried out. The (Ti,W)C sandwich cermet tool's mechanical properties are greatest when the middle layer has an Al2O3fiber content of 5 vol% and is 1 mm thick. Under these conditions, the residual compressive stress on the tool's surface is −86.2 ± 7.41 MPa. Flexural strength of 1005.10 ± 50.55 MPa, fracture toughness of 8.25 ± 0.46 MPa·m1/2, and Vicker's hardness of 21.07 ± 0.46 GPa are all higher than those of a homogeneous cermet tool by 26.26 %, 6.6 %, and 3.9 %, respectively. When compared to the data recorded with the (Ti,W)C homogeneous cermet tool, the cutting force, cutting temperature, friction coefficient, and surface roughness all indicate a decrease because of the residual compressive stress that is still present on the surface of the (Ti,W)C sandwich cermet tool. Additionally, this influence caused by stress increased the cutting distance by 15.38 %.

As an attractive prototype for neuromorphic computing, the difficultly attained three-terminal platforms have specific advantages in implementing the brain-inspired functions. Also, in these devices, the most utilized mechanisms are confined to the electrical gate-controlled ionic migrations, which are sensitive to the device defects and stoichiometric ratio. The resultant memristive responses have fluctuant characteristics, which have adverse influences on the neural emulations. Herein, we designed a specific transistor platform with light-regulated ambipolar memory characteristics. Also, based on its gentle processes of charge trapping, we obtain the impressive memristive performances featured by smooth responses and long-term endurable characteristics. The optoelectronic samples were also fabricated on flexible substrates successfully. Interestingly, based on the optoelectronic signals of the flexible devices, we endow the desirable optical processes with the brain-inspired emulations. We can flexibly emulate the light-inspired learning–memory functions in a synapse and further devise the advanced synapse array. More importantly, through this versatile platform, we investigate the mutual regulation of excitation and inhibition and implement their sensitive-mode transformations and the homeostasis property, which is conducive to ensuring the stability of overall neural activity. Furthermore, our flexible optoelectronic platform achieves high classification accuracy when implemented in artificial neural network simulations. This work demonstrates the advantages of the optoelectronic platform in implementing the significant brain-inspired functions and provides an insight into the future integration of visible sensing in flexible optoelectronic transistor platforms.

To study the influence of core-shell powders on the mechanical and cutting properties of self-lubricating cermet tools, two kinds of core-shell powders (h-BN@Al2O3and c-BN@Al2O3) were prepared by the heterogeneous nucleation method, and they were used as the additive phase of (Ti,W)C cermet tools. Compared with the addition of c-BN@Al2O3, the addition of h-BN@Al2O3produced a residual stress field around the matrix grain due to thermal mismatch, which improved the grain interface bonding strength and inhibited the crack propagation, having a better strengthening and toughening effect on (Ti,W)C cermet. The flexural strength and fracture toughness of the cermet with 5 vol% h-BN@Al2O3were 1465 ± 30 MPa and 9.9 ± 0.3 MPa·m1/2, which were improved by 38 %/23 % and 3.6 %/4.2 % compared with that of the cermet without core-shell powders and with 5 vol% c-BN@Al2O3, respectively. The cutting performance of the cermet tool with 5 vol% h-BN@Al2O3was also better than that of the cermet without core-shell powders and with 5 vol% c-BN@Al2O3. When machining 40Cr hardened steel, the h-BN in the core-shell particles was gradually exposed and formed a self-lubricating coating on the tool surface, which reduced the friction coefficient, cutting force, cutting temperature, surface roughness and chip deformation coefficient. Because the tool had both self-lubricating properties and excellent mechanical properties, the wear resistance was significantly improved and the tool life was extended to >8800 m. Within the effective cutting distance, the surface roughness of the workpiece was kept at 0.91–1.37 μm. The research results showed that the core-shell powders in the matrix grain can improve the mechanical properties because of the residual stress mechanism, and the cutting performance of the tools can be improved by its self-lubricating characteristics, so this self-lubricating cermet tool is an ideal dry-cutting tool.

Aiming at the problems of serious tool wear when ceramic tools are cutting hardened steel. The effects of SiC nanofluid on the cutting performance of Al2O3/TiC ceramic tools were investigated in terms of cutting temperature, surface roughness, cutting force, the friction of coefficient and tool wear based on Nanofluid Minimum Quantity Lubrication Technology (NMQL). It was found that the use of SiC nanofluid minimum quantity lubrication (SiC-NMQL) has the ability to reduce ceramic tool wear compared to dry cutting. Under the equal-distance cutting length, the tool with NMQL technology can reduce the wear by 55.1 %, the cutting temperature by 41.5 %, and the surface roughness by 19.2 % at a higher cutting speed. In addition, by further studying the effect of different SiC particle sizes in nanofluids on ceramic tool life, it was found that nano-scale SiC increased the life of ceramic tools by 44.4 %‑46.7 %, which was 12.2 %‑14 % higher than that of sub-micron SiC.

Due to the poor strength and toughness of cubic boron nitride tool, it is easy to have poor tool durability and chipping during machining. In order to solve this problem, carbon nanotubes (CNTs) reinforced cubic boron nitride (cBN) tool was fabricated by spark plasma sintering (SPS). The results show that the uniformly dispersed CNTs enhance the discharge property of the composite powders during SPS sintering, accelerate the material densification process, and improve the sintering effect of cBN. When the sintering temperature was 1475 °C, the fracture toughness and flexural strength of the tool with 0.50 wt% CNTs are 7.16 MPa·m1/2and 635 MPa, respectively, which are 13.7 % and 75.4 % higher than that of the tool without CNTs. The improvement of mechanical properties of CNTs reinforced cBN tool materials was mainly due to the effect of CNTs drawing, bridging and grain refinement. In the cutting of 45 carbon steel, the effective cutting distance of the tool with 0.50 wt% CNTs was 16,000 m, which was 33.3 % higher than that of the tool without CNTs. The addition of CNTs can improve the abrasion resistance of the tool and machining quality of the workpiece.

Cemented carbide, alloy cast iron and stainless steel have been extensively utilized in the fields of energy, aerospace and other industries due to their excellent properties. However, above difficult-to-machine materials have also presented significant challenges for machining tools. Correspondingly, it is of the interest of the present study to design, manufacture and evaluate the performance of a laminated graphene composite ceramic tool (marked ATBGN). With the Al2O3/TiN as the matrix layer (marked ATN) and Al2O3/TiB2/graphene (marked ATBG) as the surface layer, the Al2O3/TiB2(marked ATB) ceramic tool was also prepared. Experimental results showed that, the fracture toughness of ATB and ATBG was 5.19 MPa·m1/2and 7.35 MPa·m1/2, respectively. The ATBGN showed the highest fracture toughness of 8.65 MPa·m1/2, which was 66.7 % and 17.7 % higher than that of ATB and ATBG, respectively. The effective cutting distance of ATB, ATBG and ATBGN was 4100 m, 5200 m and 6100 m, respectively. The graphene nanoplatelets played the role of self-lubrication during the cutting process, which significantly reduced the friction coefficient, and the surface residual compressive stress improved the wear resistance of the laminated graphene composite ceramic tool.

Dimple-textured surfaces of square arrays with different geometrical parameters (area density, diameter and depth) were prepared on the surface of GCr15 steel. The friction and wear experiments were carried out under the lubrication of Suspension of graphene and liquid crystal 4-n-pentyl-4'-cyano biphenyl (5CB). By controlling the area density, diameter and depth of the dimples, the lubrication performance of laser surface texturing under the condition of starved lubrication was analyzed, and the reducing friction and wear resistance mechanism of laser surface texture was preliminarily discussed. The lubrication performance of the dimple-textured surface is best when the depth of the dimple is 10 μm, the area density is 8%, and the diameter is 100 μm. The friction coefficient at this textured parameter is 0.031, which is a 32.6% decrease compared to the untextured surface (0.046). The reduction friction mechanism of the textured surface is mainly to improve load-bearing capacity, store lubricant, reduce contact area and secondary lubrication. Meanwhile, XPS analysis shows that during the friction, the graphene/5CB suspension has a tribochemical reaction in the textured surface, and a chemical reaction film is formed on the steel surface. The research results can provide theoretical guidance for the optimization of texture geometric parameters under different application conditions.

In the era of the Internet of Things and the rapid progress of artificial intelligence, there is a growing demand for advanced dynamic vision systems. Vision systems are no longer confined to static object detection and recognition, as the detection and recognition of moving objects are becoming increasingly important. To meet the requirements for more precise and efficient dynamic vision, the development of adaptive multimodal motion detection devices becomes imperative. Inspired by the varied response rates in biological vision, we introduce the concept of critical flicker fusion frequency (cFFF) and develop an organic optoelectronic synaptic transistor with adjustable cFFF. In situ Kelvin probe force microscopy analysis reveals that light signal recognition in this device originates from charge transfer in the poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene)-co-(1,3-di(5-thiophene-2-yl)-5,7-bis(2-ethylhexyl)-benzo[1,2-c:4,5-c′]dithiophene-4,8-dione)] (PBDB-T)/pentacene heterojunction, which can be effectively modulated by gate voltage. Building upon this, we implement different cFFF within a single device to facilitate the detection and recognition of objects moving at different speeds. This approach allows for resource allocation during dynamic detection, resulting in a reduction in power consumption. Our research holds great potential for enhancing the capabilities of dynamic visual systems.

Al2O3based self-lubricating ceramic tool materials with the addition of CaF2@Ni–B were prepared using the vacuum hot-pressing technique. The microstructure, mechanical properties and cutting performance of the material with different contents of CaF2@Ni–B were studied. Compared to its counterpart tool material without CaF2@Ni–B, the fracture toughness and flexural strength of the Al2O3/TiB2/(CaF2@Ni–B) self-lubricating ceramic tool materials increased by 40.5 % and 10.1 %, and the tool life increased by 25 %.

Acenes/heteroacenes, the most widely studied small‐molecule organic semiconductors, always possess linear structures. In this work, three stable, soluble and angular π‐extended hepta‐thienoacenes with an internal carbazole, that is, thienobenzo‐fused carbazole (DTBCz) were synthesized via a four‐step tandem method. The tandem synthesis starting from carbazole derivatives led to interesting isomeric effects. The synthetic regioselectivity was discussed in detail. Their physical properties and electron density distributions were studied by UV/Vis absorption, photoluminescence, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), cyclic voltammetry (CV) measurements, and theoretical calculations. Their potentials as semiconducting materials were evaluated by fabricating the solution‐processed organic field‐effect transistors (OFETs). The more angular shaped isomer of DTB[32,34]Czdisplayed the best performance with hole mobility up to 0.0044 cm2V−1s−1in devices with a thickness of ca. 115 nm. Particularly, the performance of DTB[32,34]Cz‐based devices showed less dependence on the thickness of their active layer. Ace(ne)s up the sleeve: Angular shaped hepta‐thienoacenes with internal carbazole have been developed. Field‐effect hole mobility up to 4.4×10−3cm2V−1s−1and current on/off ratio=1.85×104in air for DTB[32,34]Czhave been demonstrated in thick active layer devices with the top‐contact bottom‐gate FET device structures, representing an important step toward the solution‐processed OFET application of angular shaped acenes.

In this study, a new type of (Si3N4/TiC/(h-BN@Al2O3)) ceramic material containing different amounts of coated h-BN were prepared by vacuum hot-pressing sintering. Microstructural analysis showed that the h-BN@Al2O3particles were dispersed homogeneously and that the particles were tightly bound in the matrix, as determined by scanning electron microscopy. The effects of h-BN@Al2O3content on the mechanical properties of the composites were also investigated. The optimal content of h-BN@Al2O3was 10 vol.%. The flexural strength, hardness, and fracture toughness of the material were increased by 22.2 %, 27.0 %, and 5.9 %, respectively, relative to the material to which uncoated h-BN was added.

Ti–6Al–4V alloy, as a typical difficult-to-machine material, is prone to problems such as large cutting forces, high cutting temperatures, and serious tool wear during the cutting process. Ti1-xAlxN coated tools are widely used in machining Ti–6Al–4V alloys. The main wear forms of Ti1-xAlxN coated tools are coating cracking and delamination. After the coating has been delaminated, the tool substrate is in direct contact with the workpiece material, aggravating tool wear and shortening the tool life. Therefore, the milling process of Ti1-xAlxN coated tool cutting Ti–6Al–4V alloy was performed using FEM. The effects of Al contents (Ti0·48Al0·52N, Ti0·38Al0·62N), coating thickness (2, 3, 4 μm), and tool substrate (Cemented Carbide Grade K, M, P) of Ti1-xAlxN coated tools on the cutting performance (cutting force, cutting temperature, maximum principal stress, the temperature and stress of coating-substrate interface) and tool wear were discussed. The influence of the maximum principal stress, the temperature and stress of coating-substrate interface on tool wear were analyzed. This paper can provide a reference for the design and optimization of Ti1-xAlxN coated tools by investigating the wear of Ti1-xAlxN coated tools cutting titanium alloys, which can be used to slow tool wear and prolong tool life.

In this paper, spark plasma sintering (SPS) was used for the first time to rapidly densify Al2O3-based granulated powders at different temperatures, and the sintering mechanism of SPS was analyzed. It is found that the optimum sintering temperature of ceramic materials is 1450 °C. Under the action of rapid heating rate (100 °C/min) spark sintering and strong electric field generated by low temperature and large current, the transport and migration of substances are accelerated, and the grains can grow effectively. The slip rearrangement between the particles caused by the discharge effect promotes the discharge of all the gases produced by the pyrolysis of organic matter, and finally the sintering densification degree of the material is optimized.

SiC-coated h-BN powders ((h-BN)/SiC) were used to substitute h-BN as solid lubricant to prepare Al2O3/TiC/(h-BN)/SiC self-lubricating ceramic cutting tool materials using hot pressing. Microstructure and mechanical properties of the material were studied. Overall improvements in Vickers hardness and fracture toughness were obtained compared with that of Al2O3/TiC/h-BN. The coating of SiC blocks direct contact between h-BN and Al2O3/TiC and hence enables h-BN particles to bond more closely with Al2O3/TiC. The density of the material was dramatically improved because of the decrement of voids around h-BN particles. Dry turning tests were carried out to investigate the wear resistance of the materials when cutting 40Cr quenched and tempered steel. Enhancement in wear resistance, which may result from the improvement in mechanical properties, was observed.

Despite remarkable advances in the development of organic field-effect transistor (OFET) memories over recent years, the charge trapping elements remain confined to the critical electrets of polymers, nanoparticles, or ferroelectrics. Nevertheless, rare reports are available on the complementary advantages of different types of trapping elements integrated in one single OFET memory. To address this issue, we fabricated two kinds of pentacene-based OFET memories with solution-processed amorphous and β-phase poly(9,9-dioctylfluorene) (PFO) films as charge trapping layers, respectively. Compared to the amorphous film, the β-PFO film has self-doped nanostructures (20–120 nm) and could act as natural charge trapping elements, demonstrating the synergistic effects of combining both merits of polymer and nanoparticles into one electret. Consequently, the OFET memory with β-PFO showed nearly 26% increment in the storage capacity and a pronounced memory window of ∼45 V in 20 ms programming time. Besides, the retention time of β-PFO device extended 2 times to maintain an ON/OFF current ratio of 103, indicating high bias-stress reliability. Furthermore, the β-PFO device demonstrated good photosensitivity in the 430–700 nm range, which was attributed to the additive effect of smaller bandgap and self-doped nanostructures of β-phase. In this regard, the tuning of molecular conformation and aggregation in a polymer electret is an effective strategy to obtain a high performance OFET memory.

As a fascinating information storage device, organic transistor memory based on molecular charge storage elements (MCSEs) has attracted great research interest. However, the charge storage mechanism of MCSEs is ambiguous due to their complex charge dynamic behaviors. Herein, the dipole moment effects on the charge trapping process and the performance of transistor memory are revealed based on cruciform spiro[fluorene-9,9′-xanthene] (SFXs), incorporating cyano moieties, as the typical electron-withdrawing substitution. The characterization of electrostatic potential (ESP) calculation, UV–vis, photoluminescence, and crystallography of SFXs shows the SFXs MCSEs with weaker dipole moment through symmetrical substitution. A series of prototype transistor memories based on SFXs exhibit an erasable type feature with smart photoresponsive behavior. The weaker dipole moment ones possess larger memory window (∼40 V), higher charge trapping density (>1 × 1013cm–2), and higher programming speed (1014–1011cm–2s–1). The hole trapping process is dominated by the dipole moment rather than the charge dissipation when compared with different SFXs at the same HOMO level. Rather good charge retention property (>104s) and large on/off ratio (∼104) are obtained by blending SFXs with polymer dielectrics in optimized devices. The dipole moment effects on the charge trapping behavior provide not only the design of high performance transistor memory but also the smart information encryption in future data storage.

We report a green and efficient method for chemoselective deoxidization of graphene oxide viathe ultraviolet irradiation catalyzed with 2,2,6,6-tetramethyl-4-piperidinol. While the sp2-hybridized oxygen functional groups are removed after the reduction, the epoxy and hydroxyl groups are retained in the chemoselectively reduced graphene oxide (CrGO). The obtained CrGO nanosheets exhibit the high solubility and excellent electronic stability, which allows for the fabrication of thin film devices through a solution processing. As a proof of concept, a CrGO-based write-once-read-many-times memory device with the desirable stability and long-time operation is fabricated.

We demonstrated a facile yet effective strategy for self-assembly of polymer end-tethered gold nanorods (GNRs) into tunable two-dimensional (2D) arrays with the assistance of supramolecules of hydrogen bonded poly(4-vinyl pyridine) (P4VP) and 3-n-pentadecylphenol (PDP). Well-ordered 2D arrays with micrometer size were obtained by rupturing the assembled supramolecular matrix with a selective solvent. The formation of long-range ordered 2D arrays during a drying process was observed via small-angle X-ray scattering. Interestingly, the packing structure of the ordered arrays strongly depends on the molecular weight (Mw) of the polymer ligands and the size of the GNRs. By increasing Mwof the polymer ligands, tilted arrays can be obtained. The average angle between GNRs and the surface normal direction of the layered 2D arrays changes from 0 to 37° with the increase in Mwof the polymer ligands. A mechanism for assembly behavior of dumbbell shapes with a soft shell structure has been proposed. The resulting GNR arrays with different orientations showed anisotropic surface-enhanced Raman scattering (SERS) performance. We showed that the vertically ordered GNR arrays exhibited ∼3 times higher SERS signals than the tilt ordered arrays. The results prove that the polymer end-tethered GNRs can be used as a building block for preparing the tilted 2D arrays with tunable physicochemical properties, which could have a wide range of potential applications in photonics, electronics, plasmonics, etc.